Three-dimensional surface measurement using grating projection method by detecting phase and contrast

A grating projection method using a stereomicroscope is developed to provide a surface profile measurement The phase shilling technique is applied for high accuracy detection of the projected fringe. To overcome 2 pi phase jump caused by large step in height and to detect absolute height from the fringe number, contrast detection of the projected pattern is available. The contrast varies in relation with the distance between the sample and the objective lens. This variation is almost as same as optical sectioning that is usually used in confocal microscopy. The fast reconstruction procedure is proposed to analyze the focal point from a few images. This method is demonstrated and conformed to measure the steep surface profile of a test sample.