SURFACE AREA MEASUREMENT USING CURVED SCREEN DEFLECTOMETRY FOR INCREASED DYNAMIC RANGE AND SENSITIVITY

摘要

Phase measuring deflectometry has been introduced as a promising solution to providing fast full-field non-contact surface area measurements of specular freeform surfaces [1]. The system measurement is based on the volumetric geometry of the screen, test part, and camera system; and, calibration of the system is usually done assuming certain standard models for the components along with triangulation-based photogrammetric techniques for position estimation. Many works have aimed at reducing errors that are introduced in the geometric calibration which is the main factor limiting the accuracy of the measurement. Calibration and positioning of the deflectometry screen is based on a perfect flat plane model with evenly spaced pixels. However, the shape of the commercially available LCD screens can have considerable deviations from a flat screen due to fabrication errors, mechanical mounts, etc.