Fizeau interferometry with computer generated hologram for mid-spatial wavefront measurement of lens with long focal length

Mid-spatial frequency errors can lead to self-focusing and power loss in a high-power laser. This paper describes the use of a binary phase computer generated hologram (CGH) to measure the mid-frequency wavefront of lens with long focallength. Thus, the designed CGH can provide reference aspheric wavefront with high-precision, in the meantime greatly shorten air space, thereby reducing the effect of vibration and air turbulence. Moreover, the use of power spectral density (PSD), structure function (SF) and autocorrelation function (ACF) for the specification and characterization of lens midfrequency wavefront are presented. The direct relationship between PSD, SF and ACF are analysed by the quantitative evaluation of the wavefront aberration. Analysis of different evaluation method help to understand the light transmission characteristics, and the area structure function and autocorrelation function can be complementary methods for specifying and representing the spatial content of optical surface errors.