Research And Implementation Of Real-time 3D Microscopic Measurement Technology Based On Structured Light

With the rapid development of electronic information industry and the continuous improvement of industrial manufacturing,miniature devices such as micro-sensors,integrated circuits and MEMS chips are being applied to various fields of production,which accompanied with it is the needs of the 3-D surface detection.Structural light-based microscopic measurement technology has an application prospect in the field of industrial 3-D microscopic detection due to its advantages of non-contact,high precision and low cost.High-speed,high-accuracy phase acquisition and system calibration are two key issues in this technology.Based on the background,this paper built a real-time 3-D microscopic measurement system based on structured light.In the phase extraction part,the traditional Fourier transform method was improved,and the background normalized Fourier transform method was proposed.The problem of spectrum aliasing was solved while the advantages of high measurement efficiency was kept.So that the accuracy of the wrapped phase was improved.In the phase unwrapping part,the phase unwrapping method based on the minimization of projection distance was proposed to solve the problem that the high-frequency wrapping phase was difficult to be unwrapped.Meanwhile,the optimal fringe wavelength selection strategy for this method was used to design the fringe wavelength for the measuring system,which increased the stability of phase unwrapping.The reliability guided compensation of fringe order error was used to correct the phase unwrapping error,which ensured the correctness of the absolute phase.In the part of system construction,the Greenough-type stereomicroscope was used and tis two separate and certain angle optical paths was acted as the projection optical path and the image acquisition optical path,respectively,thus the field of view was reduced.Meanwhile,a calibration method for this system was proposed according to the geometric coordinates of the phase and depth.By this way,the phase information can be converted into the depth information.Experiments showed the real-time 3-D microscopic measurement system built in paper has a depth measurement precision of 5.9?m and a 3-D reconstruction rate of 80Hz,which meets the requirements of high-precision and real-time measurement.Through software system,the real-time 3-D results of micro-objects can be observed from multi angles.It can provide an effective solution for the on-line detection of the 3-D morphology of the micro devices.