| Spherical lens is an important optical component for high power laser drivers, high precision detection of the transmitted wave front of which is to limit the domestic spherical lens processing quality, laser alignment system to improve the accuracy of key parameters. Precision of spherical lens wavefront measured by relative interference is limited by the precision of standard spherical lens and the rear flat. To remove the error of standard spherical lens and the rear flat and improve the test precision of spherical lens wavefront, an absolute method:three position-shifting method is proposed, and in order to compare with the method, rotating average method is applied.The theory formula of the two method is deduced in detail, and the simulation is performed. The simulation results show that the RMS of residual wavefront obtained by three position-shifting method is less than lnm and the RMS of residual wavefront obtained by rotating average method is1.3nm, theoretical error to achieve high accuracy detection. Thus the two methods can realize high accuracy measurement of spherical lens wavefront.Absolute test experiment system based on three position-shifting method is designed. Three kinds of methods are used to test the same spherical lens, including relative measurements, three position shift subtraction method and rotating average method. Theory is validated in this paper. The error sources of three position-shift method and rotating average method in the experiment is summarized. Three aspects are analyzed. Firstly, in the three position-shifting method, the influence on the test results, which is caused by the rotation error of testing lens, consistency error between the tested lens and the movement error of rear flat is analyzed. Secondly, the impact of the rotation error of tested lens are studied in rotating average method.Thirdly, in five steps, seven steps and thirteen step phase algorithm,the phase error came from PZT phase shifting error is discussed.In spherical lens wavefront error measurement, three position-shifting method can effectively reduce the influence of standard spherical lens and rear flat, and has a good guidance for processing and alignment spherical lens. |
