Research On 3D Shape Measurement System Of Small Scale Object Based On Grating Projection

In optical measurement technology,raster projection technology has always been the most widely used branch of the development.On the measurement object,due to the integration requirements of different fields,the size of the device tends to be miniaturized,making three-dimensional measurement of small scale objects become more and more important.Due to its simple principle,high measurement accuracy and fast speed,the measurement technology based on grating projection has been used more and more in the measurement of small objects,and has become one of the important directions in the current measurement field.In order to measure the three-dimensional shape of small objects with a size less than 20mm×15mm and a height of about 5mm,this paper combines grating projection technology to build a measurement system,which focuses on the key technologies and system design used in the system completion process.The main work of the study is as follows:The research status of grating projection technology and three-dimensional measurement technology of small scale objects at home and abroad is summarized,and the overall framework of the system is determined in principle.Based on the theoretical technique of grating projection method,the principle of phase shift method and phase unwrapping is introduced,and the specific implementation process is given.Then the simulation experiment is used to verify the feasibility of the measurement principle.In addition,considering the influence of the nonlinear response of the projector and camera on the phase calculation in the measurement system,a nonlinear phase error compensation method for two-step projection is introduced.The simulation also shows that the method can effectively improve the accuracy and stability of phase calculation.Starting from the two commonly used system calibration methods of explicit calibration and implicit calibration,the imaging model of the camera is introduced,and the implicit calibration formulas for height calibration and lateral calibration are derived.At the same time,the specific calibration process in two directions is given separately.According to the system structure and measurement principle,the model of the main optical components in the 3D measurement system is determined,and the final hardware measurement system is built,and the system software control interface is designed to realize the automation of the measurement process.Finally,the experimental verification is carried out.The accuracy of each method in the system is illustrated by specific experiments.The measurement error of the system in height direction and lateral dimension is obtained,and finally realize the three-dimensional shape reconstruction of small scale objects.