Quick Configurations Time Domain OCT Time Domain Signal for δ-like Object Missing facts More realistic example Possible solution Fourier Domain OCT Fourier Domain Signal for δ-like Object Noise removal More realistic example Diffraction Effects in FD-OCT Born Approximation Direct application to the OCT Rytov Approximation Direct application to the OCT

1. Time Domain and Fourier Domain
OCT
• Quick Configurations
• Time Domain OCT
• Time Domain Signal for δ-like Object
• Missing facts
• More realistic example
• Possible solution
• Fourier Domain OCT• Fourier Domain OCT
• Fourier Domain Signal for δ-like Object
• Noise removal
• More realistic example
• Diffraction Effects in FD-OCT
• Born Approximation
• Direct application to the OCT
• Rytov Approximation
• Direct application to the OCT

2. Time Domain OCT

3. Fourier Domain OCT

4. Time Domain Signal

6. What is missing in conventional
TD-OCT
Refractive index of the whole sample has been
considered constant.
Reflectivity of each layer does not depend on
the refractive index.the refractive index.

7. Layered sample with different
refractive indices
z0
z1
z2
z3
n0
n1
n2
n3z3 n3

8. Main difficulty arises here is that the thickness and
refractive index are coupled together

9. Possible solution: oblique illumination

11. Successive Interferograms

12. Maximizing the first term yields:
Maximizing the second layer in two different angles yield:
Just functions of n1 constants
The left hand side is just the function of n1 and
may be solved for the refractive index.

13. FD-OCT

14. More deeper into the sample corresponds to higher frequency detection

17. Noise removal
FT removes DC and Autocorrelation terms FT removes mirror image

19. Layered sample with different
refractive indices
z0
z1
z2
z3
n0
n1
n2
n3z3 n3

20. Main difficulty arises here is that the thickness and
refractive index are coupled together

21. Diffraction Effects in FD-OCT
Helmholtz eq.
Scattering Potential

22. Born Approximation
Using the angular spectrum representation yields
Born approximation works well
just for very small objects

23. Direct application to the OCT

24. Rytov Approximation
Rytov ApproximationRytov Approximation

25. Direct application to the OCT
the power spectrum of the
light source does not play a
role.