Non-interceptive profile measurements via light-emission based tomography technique DITANET International Conference: Accelerator Diagnostic Techniques

Non-interceptive profile measurements via light-emission based tomography technique

DITANET International Conference: Accelerator Diagnostic Techniques

Cherry May Mateo- DITANET, CEA Saclay

Co-authors: G. Adroit, R. Gobin, Y. Sauce, F. Senée, O. Tuske

2

Motivation

Increased demand

It must not perturb the beam

It must not be destroyed by high current beam (kilowatt beam power)

Optical Profilers

Beam Induced Fluorescence (BIF) Monitor at GSI*

Beam Ionization Optical profile monitors

Non-destructive diagnostics

*F. Becker et al., Beam Induced Fluorescence Monitor for Transverse Profile Determination of 5 to 750 MeV/u Heavy Ion Beams, Proceedings of DIPAC 2007, Venice, Italy

Schematic of BIF at GSI*

Cherry May Mateo/ DITANET International Conference/ 11.11.2011/Seville, Spain

Beam direction

rr

Optical beam profile

4

Optical Profiler in IPN/CEA

*P. Ausset, et. al., Transverse Beam Profile Measurements for High Power Proton Beams, Proceedings of EPAC 2001, Paris, France

Beam profiles of proton beam

Profiles obtained with different gases but with constant gas pressure.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 10 20 30 40 50 60 70

Intensité faisceau (mA)F

luo

resc

ence

(u.a

.)

656.2 nm

486.1 nm

434 nm

410.1 nm

Ha

Hb

Hg

Hd

0lum beamI I n

*Pottin, B, (2001) Etude d’un profileur optique de faisceaux intenses de protons par absorption laser, Doctor of Science thesis. Institut de Physique Nucléaire

Intensified CCD camera was used to capture beam image


5

TomographyTomography is the method used to reconstruct a 2D cross sectional image of an object given multiple flat scans taken from multiple angles around an object

Measurable

Solvable

x

y


6

How?Algebraic Reconstruction Technique for 2 Projections

f1 f2 f3

f4 f5 f6

f7 f8 f9

g1=

f1

+ f

4 +

f7

g2=

f2

+ f

5 +

f8

g3=

f3

+ f

6 +

f9

g4= f7 + f8 + f9

g5= f4 + f5 + f6

g6= f1 + f2 + f3

g A f

Projections Sparse Matrix Image


7

How?Interested in finding a vector solution f to the vector equation:

unknown slice vector

Sparse matrix or forward projection matrix

Projection data vector

Iterative Procedure


8

Initial Tests of the Algorithm


9

Initial Test

0˚ 30˚ 60˚

90˚ 120˚ 150˚

0 200 4000

50

100

0 200 4000

50

100

0 200 4000

50

100

0 200 4000

50

100

0 200 4000

50

100

0 200 4000

50

100


laserL1

L2

Rotatable mask

Gas- filled chamber

CCD camera

Reconstructed spatial distribution

G.E. Belyaev, I.V. Roudskoy, D. Gardes, P. Ausseth and A. Olivier, Nucl. Instr. and Meth. in Phys. Res. A 578, p. 47-54 (2007).

10

Numerical Test

TEST IMAGE

0˚ 30˚ 60˚

90˚ 120˚ 150˚

I HAVE


Dependence on number of Iterations

11

It .2 It.3 It.6 It.8

0 50 1000

1000

2000

3000

4000

20 40 60 80 100

20

40

60

80

100

0 50 100

20 40 60 80 100

0 50 100

20 40 60 80 100

0 50 100

20 40 60 80 100

0 50 100

20 40 60 80 100

It.15

Original Projections Reconstructed Projections

Projections measured at 90°


12

Numerical TestThe reconstructed image after 15 iterations

20 40 60 80 100

10

20

30

40

50

60

70

80

90

100

y -profile x -profile0 50 100

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 50 1000

500

1000

1500

2000

2500

3000

3500

4000

4500

Reconstructed Measured

0° 90°


13

Original image

Comparison with the source image

20 40 60 80 100

10

20

30

40

50

60

70

80

90

100

Reconstructed image


14

Experimental MeasurementsWith Ion Beams

?


Vacuum Chamber specially designed for Measurements

15

Doppler shift effect spectroscopy

Spatial density reconstruction

90°

30°

Ion Beam


Imaging and Detection

16

• Stingray F146B

• Fujinon HF25HA-1B objective

Labview


Measurements in BETSI test bench

17

Banc d’Etude et de Tests des Sources d’Ions

ECR sourceH2 dominated residual gasLow Intensity beams : 2mA H+ current at the beam stop

For valid

ation

ECR SOURCE Focusing solenoid

Analyzing Magnet

Tomographic chamber after the Magnet


Measurements in BETSI

18

0 5000

5

10

15

0 5000

5

10

15

0 5000

5

10

15

0 5000

5

10

15

0 5000

5

10

15

0 5000

5

10

15

100 200 300 400 500

100

200

300

400

500

0 200 4000

2

4

6

8

10

12Reconstructed

Measured

0˚ 30˚ 60˚

90˚ 120˚ 150˚

Bizarre ̎BANANA ̎ shape beam !NEED MORE VALIDATION


Measurements in SILHI

19

High Intensity Light Ion Source

ECRIS: 2.45 GHz - 875 Gauss. CW or pulsed mode. up to 130 mA at 95 kV kilowatt of beam power


Measurements in SILHI

20

Sole

noid

1

Sole

noid

2

Ste

ere

r 1

Ste

ere

r 2

Tomography chamber

Ion

Sou

rce


Measurements VS Sol 2 current

21

138A 142A 143A 147A 153A 159A

135 140 145 150 155 160 1650

20406080

100120140160180

0

5

10

15

20

25

projection intensity

Beam dump intensity

ISolenoid-2 (A)I b

eam

du

mp

(mA

)

I Reco

nst

ruct

ed

pro

ject

ion

Same Linear dependence


Measurements VS Sol 2 current

22

138141143147153159

BUTBeam Shape Beam position have changed !

Non linearity of the solenoid for such beam size


23

Measurements VS Steerer current

Reconstructed image w ith correction

50 100 150 200 250 300 350 400 450 500

50

100

150

200

250

300

350

400

450

500

Reconstructed image w ith correction

50 100 150 200 250 300 350 400 450 500

50

100

150

200

250

300

350

400

450

500

Varying the steerer values

DH1 +0,2DV1 -0,7DH2 +0,5DV2 -0,5

DH1 0DV1 -0,2DH2 -0,9DV2 -0,3

Position has changed Intensity remains constant BUTBeam shape has changed !


Copper « Profiler »

24

Water cooled copper block

Manual translator

Camera 1

Beam

Camera 1 for the copper « profiler » mounted on the 30° viewportBEAM SPOT

Camera 2 on the five 90°-viewport for tomographic reconstruction

Measurement region with camera 2


Camera 1BEAM SPOT

Copper block inside

the chamber

BEAM

Camera 2TOMOGRAPH

Y on VP1 VP1VP2

VP3

VP4

VP5

Copper « Profiler »

26

100 200 300 400

100

200

300

400

0 200 4000

20

40

60

Comparing the shape of the reconstructed image with 5 viewports with the copper ̎profiler ̎

Reconstructed

Measured

BEAM

Comparison between the beam spot and the reconstructed image shape is very much

comparable even with 5 projections

CAMERA1


Summary• It was demonstrated that tomography technique

can reconstruct the spatial density of the beam both for low and high intensity beams.▫6 viewports seemed to be enough to

reconstruct smooth beams.• The algorithm written in MATLAB is very fast.

▫Future use of 6 simultaneous cameras is foreseen.

27Cherry May Mateo/ DITANET International Conference/ 11.11.2011/Seville, Spain

Acknowledgements•This work is supported by the DITANET Marie

Curie European network. •CEA Saclay

▫ Romuald Duperrier▫ Wilfrid Farabolini▫ Guillaume Ferrand▫ Alain France ▫ Francis Harrault

28Cherry May Mateo/ DITANET International Conference/ 11.11.2011/Seville, Spain


29

Thank you for your attention

30

Backup Slides

31

Numerical Illustration

with MATLAB


32

Step 1 Image to Projections of the TEST IMAGE

0˚ 30˚ 60˚

90˚ 120˚ 150˚

TEST IMAGE

I HAVE


33

0 100 200 300 400 500 600 7000

2000

4000

6000

Step 2Construction of the Projection vector ̎ g ̎

0100

200

300

400

500

600

700

0

2000

4000

6000

0.5 1 1.5

100

200

300

400

500

600


34

2000 4000 6000 8000 10000

100

200

300

400

500

600 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Sparse matrix is constructedStep 3

6 projections101 x 101 image 606 x 10201 sparse matrix size


35

Step 4

0.5 1 1.5

100

200

300

400

500

6002000 4000 6000 8000 10000

100

200

300

400

500

600

=

Must solve for f


36

2 4 6 8 10 12 14

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

pix

el

valu

es

Step 5, iteration 2f is reshaped to 101× 101 image matrix

Reconstructed image

20 40 60 80 100

10

20

30

40

50

60

70

80

90

100

Reconstructed Image


An Illustration

37

2 4 6 8 10 12 14

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Number of iterations

pix

el

valu

es

f is solved iteratively


38

An IllustrationThe reconstructed image after 15 iterations

20 40 60 80 100

10

20

30

40

50

60

70

80

90

100

y -profile x -profile0 50 100

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 50 1000

500

1000

1500

2000

2500

3000

3500

4000

4500

Reconstructed Measured

0° 90°


An Illustration

39

It .2 It.3 It.6 It.8

0 50 1000

1000

2000

3000

4000

20 40 60 80 100

20

40

60

80

100

0 50 100

20 40 60 80 100

0 50 100

20 40 60 80 100

0 50 100

20 40 60 80 100

0 50 100

20 40 60 80 100

It.15

Reconstructed images with respect number of iterations

Original Projections Reconstructed Projections

Projections measured at 90°


40

Original image

An Illustration

20 40 60 80 100

10

20

30

40

50

60

70

80

90

100

Reconstructed image


Cherry May Mateo/ High Intensity Beam Diagnostics Workshop/ 27.09.2011/Massy France

41

Algebraic Reconstruction Technique for more than 2 projectionsSparse matrix for more projection angles not equal to 0˚ and 90 ˚

How?

C4

C1

C2

C3 More angles more

complicated sparse matrix

Number of rows

Number of columns

Optical Profiler in IPN/CEA

42

*P. Ausset, et. al., Transverse Beam Profile Measurements for High Power Proton Beams, Proceedings of EPAC 2001, Paris, France

DlH3+

DlH2+

DlH+

Faisceau d'hydrogène

H+ H2+

H3+

Balmer H

656.2 nm

coscv

0

Doppler Shift Spectroscopy allows discrimination of different beam components

*Pottin, B, (2001) Etude d’un profileur optique de faisceaux intenses de protons par absorption laser, Doctor of Science thesis. Institut de Physique Nucléaire

H+

r

λ

H2+

Hα


Tomography

43

By Fourier Slice Theorem, EXACT value of f(x,y) can be calculated given an infinite number of projections

( ) ( ( , ), ( , ))

( cos sin , sin cos )

n n ng s f x s t y s t dt

f s t s t dt

g

2 2 ( cos sin )( , ) ( , )j t j x yg s e dt f x y e dxdy

g

Fourier Slice theorem:

θ

st

g(s,θ)

x

y

θ


44

How?Iteration process

g Vector of projection dataf Vector of unknown slice dataA Matrix such that g = Afaij Value of element located at the ith

and jth column of matrix A

i Projection subscriptj Pixel subscriptgi Number of counts in the ith bin of the

projection datasetm Number of pixelsn Number of bins

1( ) ( )( )

k kk

Measured projectionsImage Image Normalized Backprojections of

Projections of image

1

1

1 1

( )( )

( )' '

'

knk j i

ijj n m kiij ij j

i j

ff a

a a f

g


Documents

Non-interceptive profile measurements via light-emission based tomography technique DITANET International Conference: Accelerator Diagnostic Techniques