Method for quickly imaging absorption type defects of large-aperture reflecting film element

Abstract

The invention discloses a method for quickly imaging absorption type defects of a large-aperture reflecting film element based on a photo-thermal imbalance technology. Modulated high-power laser is collimated and expanded to form large-size excitation light spots to irradiate and heat a reflective thin film element, and absorption type defects of a thin film generate periodic modulation temperature distribution on the surface of a sample, so that the reflectivity or transmittance of a defect area is periodically changed. After another low-power laser beam with a certain wavelength is collimated and expanded to form a large-size detection light spot, the large-size detection light spot is irradiated to the same area, irradiated by a heated laser beam, of the reflective film element at a certain incident angle, and the light field distribution of the detection laser beam reflected or transmitted by the film is imaged to a CCD target surface through an optical imaging system to be recorded. And a light field intensity image recorded by the CCD is analyzed to determine the absorptive defect of the irradiated area and the corresponding characteristics thereof. According to the method, the single detection area is greatly increased, and the rapid detection of the absorption type defect distribution of the large-aperture reflection film element becomes possible through scanning.

Description

Technical field [0001] The invention relates to the field of laser optical element detection, in particular to a method for high-resolution, rapid and non-destructive imaging detection of absorption defects of large-aperture reflective film elements. Background technique [0002] The light absorption characteristic is an important index to measure the quality of laser optical components. For high-power laser systems, the characterization and control of the absorption loss distribution of laser optical components is particularly important, because absorption can cause laser energy loss, local temperature rise, beam quality degradation, and even laser damage. Among the many reasons for the above-mentioned problems, the absorption defect of the laser optical element is one of the main reasons. For high-power laser systems, large-aperture reflective film elements are widely used, and their absorption defects are the most important factor that ultimately leads to damage to the high-p...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is: how to improve the single detection area by utilizing the large-scale heating and detection spot and the area array detection capability of CCD while retaining the advantages of high sensitivity and high spatial resolution of traditional photothermal technology, so that large Rapid detection of absorption-type defect distribution of aperture reflective film elements becomes feasible, reduces system cost, simplifies the complexity and difficulty of measurement optical system configuration and optical path adjustment, and realizes highly sensitive detection and detection of tiny absorption-type defects of micro-large-aperture reflective film elements imaging

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