Three-dimensional surface measurement based on the projected defocused pattern technique using imaging fiber optics

Abstract

We present a three-dimensional surface measurement system using imaging fiber endoscope and the measurement is based on the focus technique in uniaxial configuration. The surface height variation of the sample is retrieved by taking into account the contrast modulation change obtained from a projected fringe pattern on the sample. The technique takes into account the defocus change of the fringe pattern due to the height variation of the sample and by a Gaussian fitting process the height reconstruction can be retrieved. A baseline signal procedure was implemented to remove back reflection light coming from the two fiber-surfaces (inlet and outlet) and also a Fourier transform filter was used to remove the pixelated appearance of the images.The depth range of the system is 1.1mm and a lateral range of 2mm by 2mm. The novelties of the implementation are that the system uses the same imaging fiber as illumination and measurement and offers the advantage of the transportability to the measurement to a confined space having potential application on medical or industrial endoscopes systems. We demonstrate the technique by showing the surface profile of a measured object.