A Method Of Collimating Wavefront Testing By Corner-cube-reflector

Optical interference test,as the standard of optical system and optical surface shape evaluation,has high measurement accuracy of nanometer level.In order to evaluate the quality of optical systems and optical components with larger apertures,it is necessary to develop interferometers with larger apertures.The basic task of the interferometer is to collimate wavefront and recept interference field imaging,so its beam collimation is directly related to the detection result.However,the longer optical path of interferometer,more collimation error of the emitted light will be seriously transmitted and added to the measurement result.As the caliber of the interferometer becomes larger,the method for detecting the collimation of the emitted light is more restricted.This paper proposes a method of collimating wavefront test for a large-aperture interferometer based on the corner cube reflector scanning.This scheme uses a small-aperture CCR to divide the outgoing wavefront of the interferometer into several subwavefronts,and takes the high-precision standard transmission flat equipped with the interferometer as the reference.The wavefront distribution is obtained by the interference of the reflected light from the standard flat and the CCR,then the central slope is extracted.Next,moving the CCR to scan the entire exit wavefront to get a series of wavefront slopes.Finally,the exit wavefront is reconstructed from all the slopes.This method makes full use of the hardware facilities of the interferometer to realize the reconstruction of the two-dimensional surface shape of the emitted wavefront.Meanwhile,it has the advantages of high accuracy and low additional cost,and is not limited by the caliber of the interferometer.The output wavefronts of the Φ100mm and Φ150mm ZYGO interferometer,Φ300mm laser phase shift interferometer and Φ600mm phase shift Fizeau interferometer are detected respectively by using CCR scanning,and their two-dimensional wavefronts and reconstructed compeletly.Subsequently,according to the results,the expanding optical path of the Φ600mm interferometer is calibrated to PV0.1623λ,RMS0.0287λ.In addition,various errors in the measurement process are discussed,the manufacturing error of the CCR is quantitatively analyzed,the creep of the standard optical flat is qualitatively analyzed,at last the algorithm is improved.