Amplitude measurement of micro-vibration with robust optical interferometer systems

• Published in: Optik (Stuttgart) Vol. 126; no. 23; pp. 4577 - 4580
• Main Authors: Yasuda, Arata, Hasegawa, Shinya, Pohtala, Joni Verneri, Miyazaki, Takao
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 01-12-2015
• Subjects: Beam displacing prism; Contactless vibration measurement; Interferometer; Laser; Micro-vibration amplitude; Interferometer; Micro-vibration amplitude; Contactless vibration measurement; Beam displacing prism; Laser
• ISSN: 0030-4026; 1618-1336
• DOI: 10.1016/j.ijleo.2015.08.072

We have proposed a novel micro-vibration measurement systems which we call Robust Optical Interferometer (ROI). ROI is consisted of a laser, optical and electronic systems. Optical system has the beam displacing prism which is a birefringence element. The prism can split a beam of linear polarization with 45° azimuth angle into two beams of linear polarizations with 0° and 90° azimuth angle. One of two beams becomes a signal beam reflected from micro-vibration object and another one is reference beam. These two beams pass through near same path, so effect of ambient noises are canceled efficiently. Accordingly, this systems are very robust for external noise. Reflected wave from a micro-vibrating object and reference wave generates an optical interference signal which is frequency modulated-periodic signal. Wave peak number N per period is proportional to vibration amplitude parameter a/λ. (a is the object vibration amplitude, λ is the wave length of laser), whose relationship is independent from object vibration frequency. We have developed the electronic system which detects vibration frequency from the interference signal and shows the output voltage proportional to a/λ. We have measured relationship between output voltage and a/λ at the object vibration frequency. And we have confirmed that we can measure the amplitude range from 0.3λ to 3.5λ with vibration frequency range between 100 and 900Hz.