Optical System Of Vibration Measurement By Laser Doppler

Laser heterodyne interfer vibration measurement has particular advantage in nano-level vibration measurement for its high precision. Through the studying on the optical system, the authors find because the unsteady or hardly ideal laser polarization state, and the defects of optical components or the imperfect adjusted, it is likely to make two different polarization states of lasers mixing at the arm interferometer, which leads to the interference fringes unsteadiness. So that causes a larger periodical nonlinearity error. Thus, nonlinearity errors have been the most important factor in the nano-level vibration measurement. In this paper, an optical system of the vibration measurement was designed, and a strict contrast analysis of influence on the steadiness of optical system about optical power, polarization state of laser and optical feedback caused by different types of beam splitters was made. It proved that the frequency mixing due to the leakage of the polarizing beam splitter can be generally neglected.After adjusting and optimizing the optical system, on basis of the M-Z interferometer optical system; the authors built a high a precision vibration measurement of optical system. Through the test results, it can be concluded that the optical system optimized is better in the nano-level vibration measurement, the amplitude and frequency of which are good for detecting effect.