17 June 2009 Auto-focusing in the scanning white-light interferometer
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Recently, the industrial optical inspection has been a mainstream in measuring 2D images or 3D profiles of microstructures. For the 3D profiling, the scanning white-light interferometer has a high resolution, but due to the broadband light source, it has the low coherence length. Thus, it is very difficult to obtain the focused image with clear interfered fringes, and the traditional auto-focusing approaches usually determine the wrong focused position. This paper proposed a useful approach by the passive auto-focusing to determine the accurate focus for the scanning white-light interferometers. Some experimental results are presented to verify the feasibility of the proposed approach.
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Wei Cheng Wang, Wei Cheng Wang, Jin-Liang Chen, Jin-Liang Chen, "Auto-focusing in the scanning white-light interferometer", Proc. SPIE 7389, Optical Measurement Systems for Industrial Inspection VI, 73892S (17 June 2009); doi: 10.1117/12.827456; https://doi.org/10.1117/12.827456


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