Simultaneous measurement of thickness and refractive index by Fresnel biprism interferometry and Fourier transform

Parnia Farsijani¹, Marzieh Amani¹, M Taghi Tavassoly² and Masoomeh Dashtdar¹

¹Department of Physics, Shahid Beheshti University, Evin, Tehran 19839-69411, Iran

²Department of Physics, University of Tehran, North Kargar st. 1439955961, Iran
Dedicated to Prof Kehar Singh on the occasion of his 84^th Birthday on July 3, 2025

A method for the simultaneous measurement of thickness and refractive index by a common-path interferometry setup is presented. The Fresnel biprism is utilized to achieve system integration and enhance stability. In this approach, the thickness and refractive index are simultaneously obtained by introducing small angular variations in the sample. The interferogram is recorded at each rotation, and its phase is extracted by Fourier method. To evaluate the proposed system, transparent plate is demonstrated with thickness of about 178 µm and refractive index of 1.52. Anita Publications. © Anita Publications. All rights reserved.
Doi: XXX
Keywords: Interferometry, Thickness, Refractive index, Fourier method, Angular variation.

Peer Review Information
Method: Single- anonymous; Screened for Plagiarism? Yes
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