In Situ Testing Method for Laser Cleaning 7075 Aluminum Alloy Based on Grating Diffraction

It is difficult to realize cleaned surface monitoring in the process of laser cleaning. Here, a new method is developed based on the grating diffraction principle. Grating-like structures will be on the laser-cleaned surface as the laser cleaning parameters (power and scanning velocity) vary. We use hue, saturation, and luminance (HSL) technology as an in situ testing method to detect the color (wavelength) and brightness changes caused by changes in the period and depth of the grating-like structures. As long as HSL data are unique and determined, these group data correspond to the unique surface, so as to monitor the laser-cleaned surface quality. The comparative experiments with various processing parameters prove that this testing method can distinguish different cleaned surfaces and meet the needs of high-precision testing. Its resolution of roughness can reach 0.022-mu m Ra.