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EUS NI spectrograph design constraints. Contents: design of normal-incidence spectrograph with ZEMAX optical quality of the single-mirror off-axis telescope possibility of three wavelength ranges between 58 nm and 126.8 nm design of focal plane with 116.8 nm to 126.8 nm channel - PowerPoint PPT Presentation
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Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
EUS NI spectrograph EUS NI spectrograph design constraintsdesign constraints
Udo SchühleUdo Schühle
Max-Planck-Institute for Solar System ResearchMax-Planck-Institute for Solar System Research
Solar Orbiter 5th EUS consortium MeetingSolar Orbiter 5th EUS consortium Meeting
at RAL on 3. March 2006 at RAL on 3. March 2006
Contents:1. design of normal-incidence spectrograph with ZEMAX2. optical quality of the single-mirror off-axis telescope3. possibility of three wavelength ranges between 58 nm and 126.8 nm4. design of focal plane with 116.8 nm to 126.8 nm channel5. some thoughts on thermal aspects:
a) Semi-transparent telescope mirrorb) Heat rejection mirror
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Based on previous design of Roger Thomas:
• development of varied-line-space grating surface for ZEMAX
• ZEMAX calculation with ellipsoid VLS grating
• modified RT design for longer wavelength channel
• verified the design complies with specs
• some possible thermal design solutions
normal-incidence design optical normal-incidence design optical calculationscalculations
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
off axis parabola telescope:aperture size: 70 mmdistance from vertex: 50 mmfocal length: 700 mmimage scale: 1arcsec = 3.4 micronsspectrograph:grating: varied-line-space on ellipsoidmagnification: 3.6image scale: 12 m/arcsecdispersion: 5 A/mm spectral scale: 60 mA/12m
(40 mA/8m)
1 arcsec
Design of NI spectrographDesign of NI spectrograph
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Design of single-mirror telescopeDesign of single-mirror telescope
1 arcsec
1 ar
csec
off axis parabola telescope:aperture size: 70 mmdistance from vertex: 50 mmfocal length: 700 mmimage scale: 1arcsec = 3.4 microns
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
• favoured wavelength ranges : 52 nm – 63 nm72 nm – 80
nm 97 nm – 104 nm
116.5 nm – 126.8 nm
• possible with siliconcarbide optics
• normal incidence design with three wavelength ranges from 58.0nm to 126.8nm
Accommodation of three wavelength Accommodation of three wavelength bands possible?bands possible?
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
900 mm
70 m
m
TVLS grating
- 71.0 nm
- 80.0 nm
- 116.5 nm (58
nm)- 126.8 nm (63
nm)
- 97.0 nm
- 104.5 nm
700 mm
Accommodation of three wavelength Accommodation of three wavelength bands possible!bands possible!
250
mmslit
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Accommodation of long-wavelength Accommodation of long-wavelength bandband
He I O VMg XO IV
C III
Si III
N V C I Si I
Mg X
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Accommodation of long-wavelength Accommodation of long-wavelength bandband
More useful dynamic range with selective photocathode distributionPresentation of wavelength channels to be given by Luca Teriaca
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Study of a dichroic telescope Study of a dichroic telescope mirror for 58 nm upmirror for 58 nm up
• mirror coating for wavelengths 58 nm and up: SiC (CVD, hex)
• a thin coating of ~10 nm provides good VUV reflectivity of 35% to 45%
• longer wavelengths can be transmitted by a transparent substrate
• mirror temperature can be minimised
• detailed thermal study is possible.
dichroic telescope mirror can transmit 90% of the heat!
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Study of a dichroic telescope Study of a dichroic telescope mirror for 58 nm upmirror for 58 nm up
Calculations of David Windt 2001 using optical constants of SiC
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
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Study of a dichroic telescope Study of a dichroic telescope mirror for 58 nm upmirror for 58 nm up
==> heat will be transmitted towards a radiator
10 nm SiC on LiF substrate*
* calculation using optical constants of Palik et al.
independent study is ongoingwith samples of SiO2and SiC coating of 5 nm, 10 nm, 20 nm thickness
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Design of single-mirror Design of single-mirror telescope:telescope:
heat rejection mirror and baffleheat rejection mirror and baffle
field of incident radiation at slit plane: +-2.6° (= size of solar image + pointing range)
corresponds to circular range of 64 mm diameter!
unpredictable thermal distortions during orbit and pointing changes unpredictable stray light in front of the spectrometer slit
toroidal pre-slit mirrortoroidal pre-slit mirror
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
Design of single-mirror Design of single-mirror telescope:telescope:
heat rejection mirror and baffleheat rejection mirror and baffle
radiator radiator
toroidal heat rejection mirror
Udo Schühle5. Solar Orbiter EUS Consortium MeetingRAL, 3. March 2006
900 mm
70 m
m
TVLS grating
- 75.0 nm
- 85.0 nm
- 97.0 nm
- 104.0 nm
700 mm
Thermal baffle design requires space for Thermal baffle design requires space for heat rejection mirrorheat rejection mirror
250
mmslit
heat rejection mirror - 116.5 nm (58
nm)- 126.8 nm (63
nm)
