Repeatability study on different interference systems

Interferometry repeatability is an important indicator for measuring instrumentation and test results. The precondition of improving the detection accuracy is to ensure high-precision repeatability, so high-precision repeatability is one of the most important indicators in precision detection. In the Fizeau interferometer, common light paths are used for the distances from the laser light source to the reference surface, from the reference surface to the detector CCD, and the reference beam and the test beam. However, the strict sense of the co-beam does not exist, and it is not absolute ideal that reference plane has high-precision surface. The test beam reflects from the measured surface will have a certain angular deviation from the reference beam. If so, it may make the reference beam and the test beam reach the CCD detector along different optical paths and generate return error accordingly. And finally it makes effects in sampling and wave surface reproduction. Therefore, using the Zygo GPI system, the 4D system and the H and L system to make research on the same optical platform for relative interferometry repeatability comparison, ensuring that the cavity length is the same, and the standard reference mirror and the tested mirror is the same. Measurements were repeated 50 times for zero-stripes, five-stripes, and ten-stripes. The PV values and RMS values of the 50 measurements make mean processing to reflect the measurement repeatability. Further repeatability error analysis is performed on the phase shift algorithm and PZT phase shifter.