Three-dimensional Measurement Of Objects Using A Fourier Transform Profilometry Method

In this paper we investigation an optical profilometric technique,Fourier Transform Profilometry. It has the advantages of only one fringe pattern is needed to full-field acquisition,system simple, high-resolution, fast processing, high calculation accuracy,suitable for immediate processing and non-contact operation,make this technology be widely used .According to the object whose surface change is big ,we do the following job in our study:1. Using the computer software mapped the image ,which is without noise interference ,comp -are to other methods of getting projection stripe, it can greatly improve the measurement accuracy .2. Establish experimental device of Fourier Transform Profilometry.Cone is the object to be measured in the experiment,which highly mutation obvious.Make projector maintain certain angle,then it project fringe pattern onto the object,camera shot down vertically,make the center of projector and camera are parallel. Accurately determine system parameters,set the angle between projector and camera.3. Acquisition picture information by program,which is rendering by MATLAB.Then read the information which is taken in digital camare,it will be uesd to operate fourier ttransform.4. Using MATLAB compile the calculation procedure for Fourier Ttransform Pprofilometry. Remove the noise in images before processing raster image,Using low-pass filter to process the image in this step.And then get level 1 spectrum after spatial filtering,then move this spectrum to central of the picture,but this diagram is a pack-phase one.Using the phase un- unwrapping algorithm to get a continuous phase diagram.Finally convert the phase informa- tion to height information of the object.It achieve the measurement of t hree-dimensional objects.Through the above work we expand the range of Fourier Transform Profilometry from the object whose surface is smooth and deformation is small to the object whose surface is rough and surface deformation is large,make the high efficiency and accurate method of measuring three dimensional of objects topography has more practical value.