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一、前言 外差干涉测量法能测量高精密透镜象差,表面形状和形变、振幅、速度等。其频率彼此靠扰的波前相干涉而产生一电差频信号,差频信号的相位与两波前之间的光程差成正比。山于信号相位与参考信号同步,因而测量精度约为2π/100rad。可用移动光栅、旋转波片或超声光调制器作为频移器件。 利用光栅的错位干涉测量法已在Ronchi试验中用于测量透镜象差。现在又提出了错位外差干涉测量法,它利用移动光栅使待测波前产生频移和空间错位。这些错位外差干涉计用于自适应光学元件中的波前校正和镜面的形状测量。
I. Introduction The heterodyne interferometry can measure high-precision lens aberration, surface shape and deformation, amplitude, velocity and so on. A frequency difference signal is generated by the wavefront coherence whose frequencies interfere with each other, and the phase of the beat signal is proportional to the optical path difference between the two wavefronts. The phase of the signal is synchronized with the reference signal so the measurement accuracy is about 2π / 100rad. Moving grating, rotating wave plate or ultrasonic light modulator can be used as the frequency shift device. Misalignment interferometry using gratings has been used to measure lens aberrations in the Ronchi test. Now put forward the dislocation heterodyne interferometry, which uses the moving grating to make the wavefront to be measured frequency shift and spatial dislocation. These dislocation heterodyne interferometers are used for wavefront correction and specular shape measurement in adaptive optics.