Development of a New Optical Coordinate Measurement Machine in Cylinder Coordinates

摘要

A new special-purpose optical coordinate measurement machine has been developed with the cylinder coordinates to solve the problem of testing aspherics with full aperture in the stage of grinding and pre-polishing .A full aperture measurement was made by testing several meridians in the point by point manner. In the aspect of hardware, the system is composed mainly by an ultra-precise air guide-way, realizing the linear motion, and a graduator, realizing the rotary motion. In the aspect of software, the mathematical model of the system was analyzed and a new algorithm for the full-aperture testing of rotationally symmetric aspherics was built. The testing software and data-processing software are written on the VC++6.0 and Matlab6.5 platform respectively. The maximum measurement range of the system is 600mm, the maximum sag: 25mm, the minimum sampling step, 1 mm and the accuracy is better than 1 urn in full scale, after the compensation of the systematic errors. The requirement in the grinding and pre-polishing process for the test of aspheres has been satisfied. The real experiments indicate: the system runs well and has a good repeatability and accuracy.