Real-time laser shape measurement using intensity correlation with phase modulation signal

Kengo Kumano; Tamaki Ideno; Yoshihiro Endo; Yosuke Tanaka

doi:10.1117/12.2666813

22 May 2023 Real-time laser shape measurement using intensity correlation with phase modulation signal

Kengo Kumano, Tamaki Ideno, Yoshihiro Endo, Yosuke Tanaka

Proceedings Volume 12327, SPIE Future Sensing Technologies 2023; 123271T (2023) https://doi.org/10.1117/12.2666813
Event: SPIE Future Sensing Technologies, 2023, Yokohama, Japan

Conference Poster

Abstract

Application of laser displacement measurement is expected in various fields such as manufacturing, medical care, and inter-vehicle distance measurement. In this paper, we demonstrate real-time shape measurement using a laser displacement measurement system based on intensity correlation with phase modulation signals, which we have been studying for years. The intensity-correlation-based laser displacement measurement system measures the intensity correlation between the probe light signal and the phase-modulated electrical reference signal by using an optical modulator. The displacement of an object is measured in real time from a simple calculation using the fundamental and second harmonic frequency components of the intensity correlation signal. The measurement range can be freely adjusted by the modulation frequency applied to the probe and local light. In the previous study, we also developed a method to extend the measurement range without deteriorating the measurement accuracy. Furthermore, the proposed system does not need sophisticated highfrequency circuits, because multiplication operation necessary for intensity correlation measurement is performed optically by using an optical modulator. In this study, we have developed an experimental setup for scanning the probe laser beam on the sample and combined it with the laser displacement measurement system. In the experiment, we used a sample with a stepwise profile composed of aluminum mirrors and successfully measured the shape of flat surfaces and steps within an error range of the order of 10^-5 m.

Citation Download Citation

Kengo Kumano, Tamaki Ideno, Yoshihiro Endo, and Yosuke Tanaka "Real-time laser shape measurement using intensity correlation with phase modulation signal", Proc. SPIE 12327, SPIE Future Sensing Technologies 2023, 123271T (22 May 2023); https://doi.org/10.1117/12.2666813

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