Research On Key Techniques Of 3D Profile Measurement By Grating Projection Method

Computer hardware's rapid iteration makes its operation ability stronger and stronger in 21st century. Along with the improving of the modern optical detection technology, optical three-dimensional contour measuring technology has been used widely for its advantages such as high resolution, no contact, no damage and fast data acquisition. Phase of the gain and phase unwrapping has been studied as the key techniques of 3D profile measurement by grating projection method which techniques. By studying these key techniques and dealing with phase data from single camera, this paper has finished the 3D profile measurement.A three-dimensional profile test scheme based on grating projection method has been established, the projector-single camera test model and its mathematical model has been constructed and a three-dimensional profile test system based on grating projection method and experimental verification has been set up. Method to gain moire fringe based on virtual grating, phase extraction based on phase shift method and phase unwrapping based on least square method are studied as key techniques in this paper.The method to gain moire fringe based on virtual is quick and convenient. First, project a standard pattern to the reference plane and grab its reflected image. Then, place the object to be reference plane and grab the reflection of the deformed grating pattern. At last the moire fringe can be gained from these two images in computer. This method can obtain three-dimensional profile information precisely and fast for its demand of only one image.The wrapped phase has been gained by virtual phase shift method according to phase shift method characteristics of extracting package phase high precision. Finally, use least square method to unwrap phase. For a standard gauge block with the thickness of lmm is measured,1.092mm and 1.127mm are gained as result by digital moire fringe method and Fourier transform method respectively.The result of researching the above key technology and the comparing with Fourier transform show that the moire profile based on virtual grating has an important value to improve date precision of profile, at the same time the result demonstrates the validity of the research method in this paper.