Critical Technique Study Of Intelligent Vibration Isolation Platform For Optical Phase-Shifting Interferometer

Phase-shifting interferometry (PSI) is a highly precise method for non-contact optical metrology. However, PSI is sensitive to external micro-vibrations in chief. Here in the dissertation, the influence of external vibrations on PSI is studied in application and innovation so as to meet the needs of optical manufacturing and measurement.Firstly, the research situation is introduced on intelligent anti-vibration techniques in optical phase-shifting interferometry. A math model for the anti-vibration platform system of the optical phase shifting interferometer is designed, and in the mean time, an anti-vibration controller is set up according to the uncertainty of the model structure and external disturbance. The purpose of this is to make the anti-vibration system effectively restrain uncertainty of the structure and the influence of vibrations, and to make the optical phase-shifting interferometer platform obtain better stability and control precision.Secondly, the application of mixed control technique of passive-and-active anti-vibrations is studied, for the first time, to the vibration platform system of the interferometer, with air spring being used as passive anti-vibration component and piezoelectric transducer (PZT) actuator as active anti-vibration component. The mixed passive and active anti-vibration system can effectively isolate vibrations within the whole frequency range. Then wavelet method is used to the time-frequency analysis for random vibration. With the overall information within low frequency range obtained, the active anti-vibration system can easily restrain the low frequency vibration signals.Finally, as to the active anti-vibration system of the phase-shifting interferometer platform, the H∞control andμcontrol are firstly used to construct the controller. And furthermore, the anti-vibration platform system of the optical phase shifting interferometer can restrain the uncertainty of the model and external vibrations of different levels and possess highly control precision and sensitivity by the intelligent control technique in the simulink and experiment. The efficiency of anti-vibration reach above 80%.