基于LMS算法的移相干涉仪环境振动控制器

环境振动严重影响移相干涉测量的过程。在运用光学外差法测得移相干涉仪环境振动信号的前提下,设计了采用高速DSP芯片的振动控制器,它对电压形式的振动信号进行采样,用自适应LMS算法分析振动信号,同时输出反馈控制信号。反馈控制信号驱动PZT光学移相器对振动引起的光程差(或波前相位)变化进行实时补偿。通过这种闭环控制,系统能够对幅频积小于100waves*Hz的环境振动进行有效补偿,实验中获得了稳定的移相干涉条纹,保证了光学测试的正确性。

Adaptive controller based on LMS algorithm for compensating environmental vibration of a phase-shifting interferometer

Environmental vibrations can severely damage the process of phase-shifting measurement. Inorder to compensating vibrations of a phase-shifting interferometer (PSI), an optical heterodyneinterferometric vibration measurement system is firstly embedded into the PSI, which outputs vibrationinformation by voltage signal. Secondly, an adaptive controller with high-speed DSP chip as its core isbuilt, which samples the vibration voltage signal and carries out analyses of the vibration signals withLMS algorithm, and outputs feedback control signal to PZT shifter of PSI for adjusting the OPD forreal-time compensating the OPD or wave-front variation induced by environmental vibrations. Thirdly,with servo control mentioned above, PSI outputs steady fringe patterns when amplitude-frequencyproduct of vibration is less than 100 waves*Hz. The structure of this adaptive PSI is presented and theoptical test results are given.