Evaluation method for evaluating the surface quality of concave axicons with high reflectivity

Abstract

Abstract We present a method based on polarization spatial phase-shifting interferometry for evaluating the surface quality of concave axicons with high reflectivity, which is achieved by double reflections of the axicon. In this method, a transmitted test beam of a phase-shifting interferometer is reflected by the reflective axicon, the transmission flat (TF) and the reflective axicon consecutively. The test beam is perpendicularly incident on the TF by the second reflection of the axicon. Then, the surface quality of the axicon can be obtained by the interference of the test beam and the reference beam in the interferometer. The surface quality of the reflective axicons with different cone angles and diameters can be rapidly evaluated in this simple measurement configuration. Experimental results are presented for the metrology of an approximately 164° cone angle sample, which agree well with the results of the profilometer.