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IPBSM status and plan
ATF project meetingMOroku
Schematics of Shintake Monitor
Modulation depth
Measured signal in FFTB at SLACT Shintake et al 1992y~65 nm beam size was measured
Beam Size
d fringe pitch crossing angle
Principle of Laser Interference Beam Size Monitor (Shintake Monitor)
Components of Shintake Monitor
Layout around ATF2 Interaction Point
Laser SystemQ-switched NdYAG Laser (wave length1064 nm)PRO350 (SpectraPhysics)
bull To make smaller interference fringe small wave length is needed second harmonics 532nm bull High power laser is needed to raise SN ratio 14Jpulse
Specifications Value
Wave length(second harmonics)
532 nm
Line width lt 0003 cm-1
Repetition rate 625 Hz
Pulse width 8 ns (FWHM)
Timing jitter lt 1 ns (RMS)
Pulse energy 14 Jpulse
Vertical Optical Table
Laser path diagram (174 deg crossing angle) Picture of the vertical optical table installed at ATF2 beam line
16
m
Electron Beam17 m
Switch of Laser Crossing Angle
174deg 30deg
8deg 2deg
Electron beamIssue of the Shintake Monitor rArr measurable beam size range is limited
(7 ndash 40 of fringe pitch) if the fringe pitch is fixed
By changing the laser crossing angle the measurable beam size range can be enlarged
continuous
fringe pitch
crossing angle
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Schematics of Shintake Monitor
Modulation depth
Measured signal in FFTB at SLACT Shintake et al 1992y~65 nm beam size was measured
Beam Size
d fringe pitch crossing angle
Principle of Laser Interference Beam Size Monitor (Shintake Monitor)
Components of Shintake Monitor
Layout around ATF2 Interaction Point
Laser SystemQ-switched NdYAG Laser (wave length1064 nm)PRO350 (SpectraPhysics)
bull To make smaller interference fringe small wave length is needed second harmonics 532nm bull High power laser is needed to raise SN ratio 14Jpulse
Specifications Value
Wave length(second harmonics)
532 nm
Line width lt 0003 cm-1
Repetition rate 625 Hz
Pulse width 8 ns (FWHM)
Timing jitter lt 1 ns (RMS)
Pulse energy 14 Jpulse
Vertical Optical Table
Laser path diagram (174 deg crossing angle) Picture of the vertical optical table installed at ATF2 beam line
16
m
Electron Beam17 m
Switch of Laser Crossing Angle
174deg 30deg
8deg 2deg
Electron beamIssue of the Shintake Monitor rArr measurable beam size range is limited
(7 ndash 40 of fringe pitch) if the fringe pitch is fixed
By changing the laser crossing angle the measurable beam size range can be enlarged
continuous
fringe pitch
crossing angle
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Components of Shintake Monitor
Layout around ATF2 Interaction Point
Laser SystemQ-switched NdYAG Laser (wave length1064 nm)PRO350 (SpectraPhysics)
bull To make smaller interference fringe small wave length is needed second harmonics 532nm bull High power laser is needed to raise SN ratio 14Jpulse
Specifications Value
Wave length(second harmonics)
532 nm
Line width lt 0003 cm-1
Repetition rate 625 Hz
Pulse width 8 ns (FWHM)
Timing jitter lt 1 ns (RMS)
Pulse energy 14 Jpulse
Vertical Optical Table
Laser path diagram (174 deg crossing angle) Picture of the vertical optical table installed at ATF2 beam line
16
m
Electron Beam17 m
Switch of Laser Crossing Angle
174deg 30deg
8deg 2deg
Electron beamIssue of the Shintake Monitor rArr measurable beam size range is limited
(7 ndash 40 of fringe pitch) if the fringe pitch is fixed
By changing the laser crossing angle the measurable beam size range can be enlarged
continuous
fringe pitch
crossing angle
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Laser SystemQ-switched NdYAG Laser (wave length1064 nm)PRO350 (SpectraPhysics)
bull To make smaller interference fringe small wave length is needed second harmonics 532nm bull High power laser is needed to raise SN ratio 14Jpulse
Specifications Value
Wave length(second harmonics)
532 nm
Line width lt 0003 cm-1
Repetition rate 625 Hz
Pulse width 8 ns (FWHM)
Timing jitter lt 1 ns (RMS)
Pulse energy 14 Jpulse
Vertical Optical Table
Laser path diagram (174 deg crossing angle) Picture of the vertical optical table installed at ATF2 beam line
16
m
Electron Beam17 m
Switch of Laser Crossing Angle
174deg 30deg
8deg 2deg
Electron beamIssue of the Shintake Monitor rArr measurable beam size range is limited
(7 ndash 40 of fringe pitch) if the fringe pitch is fixed
By changing the laser crossing angle the measurable beam size range can be enlarged
continuous
fringe pitch
crossing angle
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Vertical Optical Table
Laser path diagram (174 deg crossing angle) Picture of the vertical optical table installed at ATF2 beam line
16
m
Electron Beam17 m
Switch of Laser Crossing Angle
174deg 30deg
8deg 2deg
Electron beamIssue of the Shintake Monitor rArr measurable beam size range is limited
(7 ndash 40 of fringe pitch) if the fringe pitch is fixed
By changing the laser crossing angle the measurable beam size range can be enlarged
continuous
fringe pitch
crossing angle
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Switch of Laser Crossing Angle
174deg 30deg
8deg 2deg
Electron beamIssue of the Shintake Monitor rArr measurable beam size range is limited
(7 ndash 40 of fringe pitch) if the fringe pitch is fixed
By changing the laser crossing angle the measurable beam size range can be enlarged
continuous
fringe pitch
crossing angle
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Expected Beam Size Resolution
Expected resolution (statistical error) is evaluated by simulation considering the probable error sources
in 25 nm ~ 6 μm range less than 12 Systematic error also need to be evaluated
Simulation condition Statistical error of the Compton scattered photons (including background subtraction) 10 Electron beam position jitter 30 of beam size Jitter of interference fringe phase 400 mrad Jitter of laser pulse energy 68 1 measurement time 1 min 174deg 30deg 8deg 2deg
Fringe pitch
266 nm 103μm 381μm 152μm
Minimum 25 nm 100 nm 360 nm -Maximum 100 nm 360 nm - 6 μm
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
phase [rad]0 2 4 6 8 10 12 14
Sign
al Ene
rgy ICT
Cha
rge [arb
uni
ts]
0
20
40
60
80
100
Result of continuous run
Beam conditionbull x ~ 4 cm (setting)bull y~ 1 mm (setting)
bullBG 65GeV bullSN 30
Measurement conditionbull Crossing angle ~ 796 deg = fringe pitch ~383 m
Modulation ~ 085
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Sources of Systematic Error
other error sources e- beam position jittere- beam size jitterTilt of the laser fringe pattern with respect to the e- beam
phase = 2k yy [rad]0 2 4 6 8 10 12 14 16
Co
mp
ton
Sig
na
l [G
eV
]50
60
70
80
90
100
110
120
130
140
ideal modulation
Goodcontrast
fringe pattern
Poorcontrast
a error sourcedeterioration of the contrast of the laser interference fringe pattern
decrease in modulation depth
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
SourceMmeas Mideal
for ~300nmMmeas Mideal
for 37nm
Laser power imbalance 997 997
Laser alignment accuracy gt 981 gt 981
Laser temporal coherence gt 997 gt 997
Phase jitter gt 995 995
Laser spherical wavefront ~ 100 gt 994
Beam size growth in the fringe pattern ~ 100 999
Π Factor gt 97 96
201067 10
Beam position monitor is needed Laser focal point alignment is needed Beam optics study at upper and lower IP is needed
List of Error Sources
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Towards the 37nm Beam Size Measurement
In future 37nm beam size measurement following error sources cannot be neglectedLaser Spherical Wavefront
Alignment of laser focal point is needed
e- Beam Size Growth within the Fringe Pattern
We can estimate that influence from measurement of upper stream beam parameters and beam optical design
e- Beam Position Jitter
IP-BPM will enables us to correct beam position jitter in 87nm resolution (assuming 30 nm beam jitter)
With evaluation of all error sources (include statistical errors) we evaluate the Shintake monitor performance towards 37nm beam size measurement
in 1 min fringe scan
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Next Plan
bull Focal point scanbull Phase Monitorbull Laser position stabilization with PSDsbull (Carbon wire scanner install)bull IPBPM install (need to discuss)
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
focal point scan(174deg)
Mover
Mover
Stroke 30mmResolution 01m
Offset of beam position to the focal point of laser
Systematic error from spherical wavefront of laser
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Laser position stabilization with PSDs (1)
To monitor the drift of laser position
Put PSD at the end of long transport linedarrBetter stabilization
Plan A Plan B
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Laser position stabilization with PSDs (2)
Plan to monitor the tilt of laser fringe by 2 PSDs
beam
fringe pattern
verticallongitudinal
The beam senses fringe pattern projected on transverse- and longitudinal-plane which the beam forms on
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Summary
bull Until now the measurement by 2- 8 degmode was done and systematic error sources were studied
bull The current status and the upgrade plan was reported
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Backup
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
光路ドリフト
201067 18
気温とともに laser position がドリフト
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Laser Polarization
P-polarized reflectance of the beam splitter is not 50 since the splitter is tuned for S-polarized lightSo the existence of P-polarized light causes power imbalance of the split laser beams and makes the fringe contrast worse
after polarization adjustment with half wave plate
Ps the intensity of S-polarized lightPp the intensity of P-polarized lightP the whole intensity of laser
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
distance between beam and laser laser size0 01 02 03 04 05 06 07 08 09 1
Co
ntr
as
t [
]
97
975
98
985
99
995
100
laser alignment
alignment of y-axis
alignment of z-axis
alignment accuracy
Laser Alignment Accuracy
It is important for a good contrast to align the laser pathway with beam position
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Phase Jitter
Phase jitter of the laser light smears the fringe pattern and decreases modulation depthPhase jitter is caused by optical device vibrations
The Shintake monitor has a phase monitor and a light path length feedback system with piezoelectric deviceUsing the feedback system
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Laser Temporal Coherence
laser spectrum(FWHM)
bull If the laser temporal coherence is poor and the two laser path lengths are different the fringe pattern contrast is reduced
bull This is because each frequency component of the laser contributes to interference in different phase under the existence of laser path length difference
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Contrast Correction
Comparison with the WS measurement after Contrast correction
Magnet current [A]128 130 132 134 136 138
m]
B
ea
m s
ize
[
2
3
4
5
6
7Shintake MonitorShintake Monitor corrected
Wire Scanner
After the above corrections the measured beam size is slightly decreased but systematic shift still remains
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
If degrees and the Shintake monitor and the WS has comparable measurement result
Tilt of the laser fringe pattern with respect to the WS
Horizontal and longitudinal axes defined by the WS and those defined by the fringe pattern might be different
measured vertical beam size
vertical beam size
horizontal beam size
x
y
z
y
wire
fringe pattern
fringe pattern
laser size
beam
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Laser Spherical Wavefront
beam
fringe pattern
If beam position is away from the laser focal point when beam pass the fringe pattern beam senses courved fringe due to the laser spherical wavefront
vertical
longitudinal distance from focal point [mm]0 01 02 03 04 05 06
Co
ntr
as
t
09
092
094
096
098
1
102 x infinitesimalmx = 10
mx = 100
x horizontal beam size
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern
Beam Size Growth in the Fringe
Strong Focusing
Smaller Beam Size
Smaller Beta Function at IP
Beam Size Growth in the Fringe
Modulation Depth Degradationvertical
longitudinal
beam
fringe pattern