Vertical-scanning shape-measurement interferometry using white light is widely used to measure 3D shape of objects having step-like shape. This interferometry however cannot be used under vibrating environment. Because, it is required to accurately repeat predefined-step movements over vertical measurement range. We developed new technology which can measure the changes of optical path difference (OPD) of an interference microscope with nanometer resolution. This uses a line camera and a FPGA device and can measure OPD changes with around 20-μs interval. We built this technology onto a vertical-scanning interferometer and estimated performance of the developed technology using some vibration conditions.
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