A Research On Key Techniques Of Phase Measuring Deflectometry

With the rapid development of the electronics industry,the consumption of various types of electronic products is also increasing.In the production process of electronic products,the product quality inspection system is of vital importance.Among the various components that constitute electronic products,the quality inspection of optical components has always been a hot topic.Limited by inspection speed and inspection accuracy,the inspection of optical components in factories currently relies on human vision inspection.This situation is not conducive to inspection efficiency and stability,nor to the health of workers,so it is urgent to change.Based on the Phase Measuring Deflectometry(PMD)in structured light detection field,a modulation-assisted Phase Measuring Deflectometry is proposed in this paper.This method is called Structured-Light Modulation Analysis Technique(SMAT).SMAT is suitable for the detection of contaminants and defects of specular surfaces and transparent objects,and can be implemented by means of a light reflection system and a transmission system.According to this technique,the specific research content of this article can be summarized into the following aspects:1.Under the premise of determined reflection light path,the change of the incident light when there are contaminants or defects on the detected object is analyzed,and the photometric modulation model of SMAT is established based on the principle of photometry for the first time.In addition,a novel transmission system is proposed for contaminant and defect detection of transparent objects.Under the guidance of the SMAT model,relevant simulation and experimental results show that the modulation result based on SMAT can eliminate ambient light interference and clearly reflect the information of contaminants and defects.Thus,the effectiveness of SMAT is verified.2.To accurately describe the detection mechanism of SMAT and offer guide to system optimization work,mathematical models of SMAT based on the reflection system and transmission system are reconstructed based on the topography of the detected object.These improved models can explain the issues encountered in the applications of SMAT,such as the differentiated response in the modulation image.Relevant simulation and experimental results also verified the effectiveness of these improved models.Meanwhile,in order to solve the problem of incomplete information acquisition caused by modulation differentiated response,a modulation merged algorithm is proposed for capturing contaminant and defect information completely.3.A gray-value compensation algorithm is adopted to compensate the non-linear error of the acquired fringe patterns.Based on this algorithm,there is no need to use more phase-shifting step to reduce the non-linear error of the system,which is beneficial to rapid inspection.The effectiveness of this new detection approach has been verified by comparing with the uncompensated modulation result with the same phase-shifting step and the uncompensated modulation result with more steps.