Method for detecting washed surface of optical substrate used for laser thin film element

The invention relates to a method for detecting the washed surface of an optical substrate used for a laser thin film element, belonging to the technical field of optics. A detection procedure process comprises the following steps of: calibrating the visibility of a white light surface detection lamp by using man-made silicon oxide globules of 5 microns and 10 microns in size; carrying out scale contrast on residual grains after the substrate is washed by using silicon oxide globules of 5 microns to 50 microns in size; counting the scale and the number of the residual grains, so as to realize the semi-quantitative detection on micrometer-scale grains on the surface of the substrate with the naked eye; scanning the surface of the substrate by using a weak absorption instrument; counting the number of points of which the absorption is larger than 20ppm and less than 100ppm and the absorption value is larger than 100ppm on the surface of the substrate, thereby realizing the precise evaluation on the washing and elimination efficiency of nano-scale metal oxide powder grains on the surface of the substrate; and measuring the depth and the surface roughness of the scratch on the surface of the substrate by using an atomic force microscope, measuring and recording the number of pocking marks of which the diameters are larger than 20nm, so as to realize the quantitative evaluation on the defects on the surface of the substrate. The method has the advantages that the quantitative detection on the washed surface of the optical substrate is realized, data support is provided for the improvement of the substrate washing process, and the requirements on laser damage after the substrate is plated with films are met.