Structured laser illumination planar imaging method for filtering stray light applied to temperature sensitive paints measurement

Abstract

Stray light is the main noise source for planar imaging measurement technique, which can affect the accuracy of results directly. A method of Structured Laser Illumination Planar Imaging (SLIPI) was used to solve this issue. The key of SLIPI is periodic modulation of laser spatial intensity and implementation of post filtering algorithm. In this paper, cylindrical micro lens array was used to modulate the spatial intensity of laser periodically, which was compared with Ronchi ruling. The post filtering algorithm adopts phase-locked detection method. The signal results can be separated from the noisy image using only one measurement image by this method. SLIPI method has been used in Temperature Sensitive Paints measurement experiments. A diagnostic optical path combining cylindrical micro lens array and cylindrical mirror was designed for the need of surface light source irradiation. The results show that the method of SLIPI can be applied to most planar imaging measurement techniques, and the accuracy of two-dimensional parameter measurement can be further improved.