Ultrafast laser cleaning method and device for surface of aluminum alloy reflector

Abstract

The invention relates to the field of ultra-precision polishing aftertreatment of optical elements, and in particular to an ultrafast laser cleaning method and device for the surface of an aluminum alloy reflector. The method comprises the following steps of carrying out a photo-thermal absorption experiment on an aluminum alloy matrix and an aluminum alloy oxide film corresponding to a workpieceto be cleaned, and recording a wavelength range in which the photo-thermal absorption rate of the aluminum alloy oxide film is greater than that of the aluminum alloy; emitting the pulse laser to scanthe to-be-cleaned surface of the aluminum alloy reflector of the to-be-cleaned workpiece through a laser of which the wavelength is within the wavelength range, thereby cleaning the surface of the aluminum alloy reflector of the to-be-cleaned workpiece. The device comprises the laser, a beam expander, the reflector, a scanning galvanometer and a field lens. According to the method, the iron element pollution can be removed on the premise that the surface is not damaged, the surface reflectivity is greatly improved, and the use performance is improved.

Description

technical field [0001] The invention relates to the field of post-processing of ultra-precision polishing of optical elements, in particular to a method and device for ultra-fast laser cleaning of the surface of an aluminum alloy reflector. Background technique [0002] Aluminum alloy is a common material for structural parts and optical components in aerospace optical systems. Mirrors made of it are widely used in infrared optical systems, and have broad application prospects in the fields of visible light and ultraviolet light. With the continuous improvement of the surface accuracy requirements of optical components, single-point diamond turning (SPDT) processing of common commercial aluminum alloys cannot meet such performance requirements. Therefore, the process route for manufacturing aluminum alloy mirrors needs to further improve the surface shape accuracy and surface quality of the mirror surface after SPDT through a polishing process, so as to make it meet the appl...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention: the present invention provides a method and device for ultra-fast laser cleaning of the surface of an aluminum alloy reflector to solve the problem that a black oxide layer is formed on the surface after magnetorheology, resulting in deterioration of the surface quality and a serious decrease in reflectivity , the present invention aims at the problem that magnetorheological polishing, a key step for improving surface shape accuracy, introduces iron powder pollutants on the surface of aluminum alloy reflectors, which greatly reduces the reflectivity of the surface. Based on the difference in light and heat absorption of the two materials, The femtosecond laser is used to clean and directional remove the processed surface, which can clean the impurities and pollutants introduced by magnetorheological polishing on the mirror surface, remove iron pollution without damaging the surface, and greatly improve the reflectivity of the surface. Improve its performance and can be used for surface cleaning after magneto-rheological modification of optically complex curved mirrors

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