Compound interferometer system for large-scale optical components surface measurement

Large-scale optical components is being applied more and more widely in the astronomical optics, space optics, groundbased space target detection and identification, laser propagation in the atmosphere, inertial confinement fusion (ICF) and other fields, especially the large-scale aspherical optical component is one of key parts which play a supportive role in those fields. Large-scale optical components surface measurement instrument and technique has become a research focus of many scholars in recent years. In this paper introduced a compound interferometer system, which based on the principle of traditional Fizeau interferometer and lateral shear interferometer. In this system, produces two probe light beams by a He-Ne laser, one of probe light beams is used to measure flat optical surface by using comparison with the reference wavefront, and the other probe light beam is used to measure spherical and aspherical optical surface according to the principle of lateral shear interferometer and without using reference wavefront. Discussed in detail optical layout of the system as well as the principle of surface measurement, and the preliminary test results were given. The compound interferometer system has a compact, multi-function, and good anti-vibration performance can be used for large-scale optical plane (diameter less than 320mm), spherical and aspherical optical components surface measurement. Due to the information that lateral shear interferogram carries does not show directly the deviation between the wavefront under test and the ideal wavefront, but the wavefront difference, so the wavefront reconstruction method is more complex, and the wavefront reconstruction algorithm from lateral shearing interferograms is also analyzed and discussed.