Patent ID: 7009718

Claim:
A grating pattern projection apparatus, comprising: a light source; a liquid crystal grating; a projector for projecting a grating pattern formed by light emitted from the light source passing through the liquid crystal grating onto an object to be measured; a liquid crystal driver for driving the liquid crystal grating so that one cycle of the grating pattern has a linear intensity distribution, the liquid crystal driver prepares a triangular wave intensity distribution that a width of an area whose intensity increases linearly and a width of an area whose intensity decreases linearly are equal in one cycle of the grating pattern, and drives the liquid crystal grating so that the grating pattern has a triangular wave intensity distribution; a detector for detecting a deformed grating pattern deformed by projecting the grating pattern onto an object to be measured; and a processor for converting the linear intensity distribution of each cycle of the deformed grating pattern into a linear phase distribution for changing a phase linearly; wherein the processor detects a maximum intensity or a minimum intensity of each cycle of the deformed grating pattern, converts the intensity at each position of the deformed grating pattern into a standardized intensity with the maximum intensity or the minimum intensity as a standard, and performs proportional processing of the standardized intensity to convert an intensity that changes linearly in one cycle of the deformed grating pattern into a phase that changes linearly between 0 and 2π, and further comprises a smoothing processor for converting an intensity of the deformed grating pattern into an intensity distribution that changes smoothly, and a linear distribution corrector for correcting intensity changes in each intensity increase area and intensity decrease area of the smoothing processed deformed grating pattern into an intensity distribution that approximates a straight line, so that it changes linearly.