The kernel of modern interferometry is to obtain necessary surface shape and parameter by processing interferogram with reasonable algorithm. The paper studies the basic principle of interferometry involving 2-D FFT, proposes a new method for measuring thin film thickness based on FFT: by CCD receiving and acquired card collecting with the help of Twyman-Green interferometer, can a fringe interferogram of the measured thin film be obtained. Based on the interferogram processing knowledge, an algorithm processing software/program can be prepared to realize identification of the edge films, regional extension, filtering, unwrapping the wrapped phase etc. And in this way can the distribution of film information-coated surface be obtained and the thickness of thin film samples automatically measured. The findings indicate the PV value and RMS value of the measured film samples are 0.256 λ and 0.068 λ respectively and prove the new method has high precision.

Date Published: 20 May 2009
PDF: 5 pages
Proc. SPIE 7283, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 72832K (20 May 2009); doi: 10.1117/12.828717

Published in SPIE Proceedings Vol. 7283:
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
Yudong Zhang; James C. Wyant; Robert A. Smythe; Hexin Wang, Editor(s)