17-21 June 2007 ECBO 2007 Munich, Germany

Static depth dependent dispersion compensation in a real-time static delay line

grating-based correlation OCT system

L. Froehly, P. Sandoz, L. Furfaro, M.Ouadour

Institut FEMTO-ST; Département d’Optique P.M. Duffieux Besançon, France

17-21 June 2007 ECBO 2007 Munich, Germany

Dispersion problem in OCT

100m

•Dispersion limits axial resolution

•Dispersion depends on the material thickness

•Dispersion decreases the Signal to Noise ratio

tseS TFenc

j'

12

m1

m13

17-21 June 2007 ECBO 2007 Munich, Germany

Hardware correction

S.L.S.

M1

S1O1

O2

17-21 June 2007 ECBO 2007 Munich, Germany

Hardware correction (rapid scanning delay line)

K. F. Kwong, D. Yankelevich, K. C. Chu, J. P. Heritage, and A. Dienes, Opt. Lett. 18, 558- (1993) ->first demonstration for pulse measurements

Rollins, S. Yazdanfar, M. Kulkarni, R. Ung-Arunyawee, and J. Izatt, Rollins, S. Yazdanfar, M. Kulkarni, R. Ung-Arunyawee, and J. Izatt, Opt. Express 3, 219-229 (1998)Opt. Express 3, 219-229 (1998)

G. J. Tearney, B. E. Bouma, and J. G. Fujimoto, Opt. Lett. 22, 1811-1813 (1997) ->Application of the system to TD-OCT system

17-21 June 2007 ECBO 2007 Munich, Germany

Numerical correction

tIeeI

eItI

dTFjj

jTFd

c

1

•Phase correction in Fourier space•Influence of the phase correction on the image contrast

Quite time consumingQuite time consuming

17-21 June 2007 ECBO 2007 Munich, Germany

Grating-based Tomographic system

y

z

S.L.S.

S1M..: MirrorS: Polarizing beam splitterL1: Spherical lensS.L.S. : White light laser sourceC.B. : Polarizing beam splitterD : CCDR : Diffraction grating 530 gr/mmP : prismO… : Miroscope objectivesE : Sample

I(z)

zt

L1

M2

M3C.B.

D

P

O1

O2

R

4

17-21 June 2007 ECBO 2007 Munich, Germany

M3

M2

R

Principle

I

x↔z

17-21 June 2007 ECBO 2007 Munich, Germany

y

z

S.L.S.

S1

I(z)

zt

L1

M2

M3C.B.

D

P

O1

O2

R

4

Absorption

L. Froehly, M. Ouadour, L. Furfaro, P. Sandoz, T. Gharbi et al, Real-time optical coherence spectrotomography : proof of principle volume 6191 of Biophotonics and New Therapy Frontiers. SPIE, Apr. 2006.

17-21 June 2007 ECBO 2007 Munich, Germany

z

z

Optical Depth dependant dispersion compensation

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000loi de dispersion du réseau

pixels CCD

z

17-21 June 2007 ECBO 2007 Munich, Germany

Optical Depth dependant dispersion compensation : principle

17-21 June 2007 ECBO 2007 Munich, Germany

Optical Depth dependant dispersion compensation : principle

17-21 June 2007 ECBO 2007 Munich, Germany

Optical Depth dependant dispersion compensation : principle

17-21 June 2007 ECBO 2007 Munich, Germany

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000loi de dispersion du réseau

pixels CCD

Optical Depth dependant dispersion compensation : validation

17-21 June 2007 ECBO 2007 Munich, Germany

0 200 400 600 800 10000

0.5

1

1.5

2

2.5x 10

4 dispersion 2 lames

pixels CCD 0 200 400 600 800 10000

0.5

1

1.5

2

2.5

3

3.5x 10

4 dispersion 1 lame

pixels CCD

Optical Depth dependant dispersion compensation : validation

17-21 June 2007 ECBO 2007 Munich, Germany

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000loi de dispersion du réseau

pixels CCD

0 200 400 600 800 10000

0.5

1

1.5

2

2.5

3

3.5x 10

4 dispersion 1 lame

pixels CCD

0 200 400 600 800 10000

0.5

1

1.5

2

2.5x 10

4 dispersion 2 lames

pixels CCD

Optical Depth dependant dispersion compensation : validation

17-21 June 2007 ECBO 2007 Munich, Germany

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000loi de dispersion du réseau

pixels CCD

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000

pixels CCD

0 200 400 600 800 10000

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

pixels CCD

Optical Depth dependant dispersion compensation : validation

17-21 June 2007 ECBO 2007 Munich, Germany

Future directions: lens effect on dispersion

17-21 June 2007 ECBO 2007 Munich, Germany

Future directions : lens effect on dispersion

17-21 June 2007 ECBO 2007 Munich, Germany

Future directions : catadioptrics systems

y

z

S.L.S.

S1

M2

M3C.B.

P

O1

O2

R

4

D

17-21 June 2007 ECBO 2007 Munich, Germany

Aknowldegments

•French ANR who finances this project•Leukos innovative systems who provide us with microchip-based supercontinuums