CALIBRATION METHOD OF TELECENTRIC IMAGING THREE-DIMENSIONAL SHAPE MEASUREMENT SYSTEM

摘要

A calibration method of a telecentric imaging three-dimensional shape measurement system. The method comprises the following steps: step S1: building a telecentric three-dimensional shape measurement system; S2: controlling a telecentric projection device to project a sinusoidal fringe pattern on a translation stage, collecting, by a telecentric photographing device, the sinusoidal fringe pattern; moving the translation stage multiple times, utilizing a multi-step phase shift method to obtain an absolute phase value at a pixel point for calibration on an image plane of the telecentric photographing device, linear fitting the absolute phase value at a pixel point for calibration and a height value to obtain a phase-height conversion relation of the measurement system; S3: converting a pixel coordinate on the image plane of the telecentric photographing device to a world coordinate by calibrating parameters of the telecentric photographing device. In the method, the phase and the height satisfy a linear relationship, such that only the linear relationship between an absolute phase value of a pixel point and the height of the translation stage needs to be measured. The method has a small amount of computation, a high accuracy, a strong operability and practicality. The method further provides an orthographic transformation model of dual-telecentric lens, thus simplifying a calibration process.