Microscopic fringe projection profilometry system calibration based on double telecentric lenses

Abstract

Calibration methods for microscopic fringe projection profilometry (MFPP) system usually require complicated and time consuming system calibration. This paper proposes a convenient MFPP model and its calibration method. Compared to the conventional structured light model, the proposed model contains a telecentric imaging unit and a telecentric projection unit, and a precisely controlled moving platform was used to ensure that the optical axis of the camera is perpendicular to the reference plane. Instead of establishing a one-to-one mapping between the camera image and projector image to obtain the system parameters, the proposed model only requires to detect the width of the horizontal and vertical fringes owing to the orthographic projection characteristic of the telecentric projector, which is simpler and more convenient. The experimental results demonstrate the feasibility and high measurement accuracy of the proposed method, which shows great potential for the practical application for the MFPP measurement.