20 May 2009 Interferometric measurement method of thin film thickness based on FFT
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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.
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Gaolong Shuai, Gaolong Shuai, Junhong Su, Junhong Su, Lihong Yang, Lihong Yang, Junqi Xu, Junqi Xu, } "Interferometric measurement method of thin film thickness based on FFT", 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; https://doi.org/10.1117/12.828717

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