Three-dimensional Profile Measurement Based On Frequency-doubled Grating Projection Under The Synchronous Trigger

The computerized synchronous control system for grating projection and image acquisition is established in the technology of measuring the 3-D profile of frequency-doubled grating projection.By means of frequency-doubled grating projection,the shape height of each sampling point on the surface of the 3-D object can be independently calculated.By adding a synchronous trigger device with MC 100 chip as the core and corresponding control software in the measurement system,the fast and stable synchronous grating projection and image acquisition under the control of computer are realized,the acquisition time of a large amount of image data is greatly shortened,the automatic control of 3-D measurement is realized,and an effective means is provided for the practical locale application of three-dimensional surface shape measurement.The main contents are as follows:(1)Establish computerized synchronous control triggered projection and the double-frequency grating of 3-D profile measurement system.Under the control of the computer,the projection system projects the grating fringe image with sinusoidal brightness on the surface of the 3-D object,and the synchronous trigger system controls the image acquisition system to rapidly gather the deformed fringe image on the surface of the object.(2)Under computerized control,the working conditions of the synchronous trigger device with MC 100 chip as the core are studied.In the experiment,investigate the relationship among grating projection speed,image acquisition delay time and acquisition speed.Then find the best working parameters which suitable for synchronous triggering acquisition of specific objects.(3)The control program of the computerized synchronous acquisition system and the subsequent processing program of the acquired pictures are written.The synchronization and controllability of the acquisition system are realized by synchronous trigger.The wrapped phase of the highly correlated deformed fringe in the three-dimensional image of the frequency doubling projection grating is obtained by calculation.The unwrapped phase of each spatial frequency is calculated step-by-step by computer programming,and the relative topography height of the three-dimensional object surface is obtained.