波長走査干渉計における信号処理

概要

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A high accuracy and non-destructive absolute surface profile measuring system based on wavelength scanning interferometer has been developed. This system combined a compact interferometer based on Michelson interferometer with an electronically tuned Ti : sapphire laser for wide range wavelength scanning. This system measures absolute profile of object up to measurement height range of 1.5mm for area of 2.5mm × 5mm. The depth resolution by quantization is approximately 3 μm. For improvement of the system, signal processing methods such as laser intensity revision method, phase revision method and interpolation method are adapted. From laser intensity revision and phase revision by Hanning window, S/N ratio of peak spectrum detection improved from 12.0 to 25.4. Five types of interpolation methods are tested to improve depth resolution. Using variable width cos^2θ fitting method, the depth resolution improved up to 0.06 μm. Experiment of profile measurement of Japanese one yen coin is done, and the accuracy of measurement is approximately 2μm. The experimental results show the signal processing methods are useful for the profile measuring system.
社団法人精密工学会の論文
2003-06-05