The research of 3D small-field imaging system based on fringe projection technique

This paper presents a 3D small-field imaging system by using the color fringe projection technique to measure the small
objects having large slopes and/or discontinuous surface. A stereo microscope is used to generate a small-field projecting
field and to capture the deformed fringe patterns on the measured small objects, respectively. Three fringe sets having
the optimum fringe numbers are coded into one major color channel to generate color fringe patterns having the
maximum fringe contrast of the captured fringe images. Through one channel of the stereo microscope, a DLP (Digital
Light Processing) projector projects these generated color fringe pattern images onto the measured objects surface. From
another channel, the fringe patterns are deformed with regard to the object surface and captured by a color CCD camera.
The absolute phase of each pixel can be calculated from the captured fringe patterns by using the optimum three-fringe
numbers selection method. Experimental results on measuring 3D shape of small objects show the accuracy and
availability of the developed 3D imaging system.