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Development of Spectral Domain Low Coherence Interferometry for the Measurement of Multilayer Structure

By
Anup Kumar Sharma
(2008JID2939)

Under The guidance of
Dr. D. S. Mehta

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Instrument Design & Development Centre
Indian Institute of Technology
Delhi

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Contents
Basic principle of Low Coherence Interferometry (LCI).
Low coherent sources
Coherence gating
Fourier Domain Low Coherence Interferometry
Objective
Realization of Spectral Domain LCI using Michelson Interferometer
Work done so far
Work to be done in next semester
References

• Objective
• To develop Spectral Domain Low Coherence Interferometry(SD-LCI) for measurement of Multilayer structure parameters.

• Work done so far
1. Literature survey.


2. Simulation of spectral interferrogram using multilayer structure:-
The detector receives the intensity can be expressed as
I(k)
where
S(k) = Amplitude spectral distribution of the light source
n = Number of scattering thin plates present in the sample.
r = Suffix used for parameters in reference arm.
m = Suffix used for parameters in sample arm.
Zr = Depth of reference arm.
Rn = Reflectivity of the sample at depth Zn.



3. Realization of spectral domain LCI using Common Path Interferometer
• Work to be done
• Further improvement in the experiment will be carried out.
• Further the different low coherence source will be used to increase the depth resolution of the present system.
• To study the different type of multilayer structure such as composite materials, semiconductor materials and thin film.
• To develop the software and image processing for analyzing the recorded data.
• Determination of thickness and refractive index of various multilayer structures as mentioned above because these parameters are very important to check the accuracy and sub surface defects present in the multilayer structures.


• References
• Alarousu E, Gurov I, Hast J, Myllylä R, Prykäri T & Zakharov A (2003) Optical coherence tomography evaluating the random tissues based on dynamical processing the stochastic low coherence interference fringes. Proc. of SPIE 5140: 33-42.
• B.E. Bouma and G.J. Tearney, eds., “Handbook of Optical Coherence Tomography”(Marcel Dekker ,New York,2002)
• Ballif J, Giannotti R, Chavanne P, Wälti R & Salathé R P (1997) Rapid and scalable scans at 21m/s in optical low-coherence reflectometry. Opt. Lett. 22: 757-759.
• Baumgartner A, Möller B, Hitzenberger C K, Drexler W & Fercher A F (1997) Measurement of the Posterior Structures of the Human Eye In Vivo by Partial coherence Interferometry using Diffractive Optics. Proc. SPIE 2981: 85-93.
• Haruna M, Ohmi M, Mitsuyama T, Tajiri H, Maruyama H and Hashimoto M 1998 Simultaneous measurement of the phase and group indices and the thickness of transparent plates by low-coherence interferometry Opt. Lett. 23.