Accurate 3D measurement system and calibration for speckle projection method

Triangulation with structured light projection is a well-established deformation measurement technique, which is utilized extensively in many fields. But all the existing calibration methods need to consider the influence of lens distortion and perspective error, which is indispensable with the use of conventional lens. In order to minimize such disadvantages, the telecentric lens is a good choice. Based on speckle projection, a system for deformation measurement is developed with the telecentric lens. Correspondingly, an effective calibration method is presented in detail. Experiments are performed to validate the availability and reliability of the calibration method. Results are compared with ESPI and good agreement is found between them. The system can also be used to measure the dynamic deformation and then results are also given.