Study on the optical performance and characterization method of texture on KH2PO4 surface processed by single point diamond turning

Abstract

The analysis based on the Fourier model method indicates that the steep profile (smaller wave period or larger depth) tends to decrease the laser induced damage threshold (LIDT) of KH2PO4 (KDP) crystal. The parallel or perpendicular texture directions on the front and back surfaces have different influences on the LIDT of optical components. Power spectrum density (PSD) method can realize the information of texture period, depth and direction on certain surface, especially the angular spectrum and radial spectrum. The fractal theory covers the shortage of PSD method in charactering the texture roughness or surface processing quality. The larger fractal dimension means that the surface fluctuates sharply and lots of brittle defects exist, this is consistent with the experimental results. The circumferential profile fractal dimension distribution also can characterize texture direction, but its directing ability decreases or even is lost when the sampling extent becomes small or the surface texture is not obvious any more. The angular spectrum is more accurate than the fractal dimension in charactering texture direction.