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

Abstract

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.

Stereomicroscope as an aid in grossing and histopathological diagnosis: A prospective study

“…A small number of models can use transmitted light, where the bulb or mirror will reside beneath the object itself [ Figure 2 ]. [ 7 ] We conducted our study based on the criteria given in the Table 1 . [ 3 ]…”

Simultaneous in-and-out-of-plane deformation measurements using speckle projection and fluorescent digital image correlation

“…The third method is to use a projector to measure out-of-plane deformation and a camera to measure in-plane deformation.Since the projector can be regarded as an inverse camera, this kind of method can also be regarded as pseudo stereo vision method.Projectors can project any graphics generated by computers. In projection correlation method, they are generally divided into Fringe Projection Profilometry (FPP) [17][18][19][20] and Speckle Projection Profilometry (SPP) [21][22] .SPP can calculate the out-of-plane displacement by using the common 2D-DIC method to track the highly modulated speckle, it's easy to implement.However, FPP has a complex phase unwrapping process.So SPP is simpler than FPP.In addition, SPP can calculate by only one reference image and one deformed image, which is more suitable for high-speed measurement. However, FPP method, such as phase shifting method [23][24][25] , requires at least three accurate phase shifting images, which greatly reduces the measurement speed.If we use the single fringe pattern FPP method such as Fourier Transform Profilometry(FTP) [26][27][28] and Wavelet Transform Profilometry(WTP) [29][30][31][32] , its accuracy will be lost.…”