Optimization design of light pen for use in space coordinate measuring systems without guideway

The structural design of light pen for a space coordinate measuring system without guideway is expounded in detail. 3/4[G] redundancy technique is applied in the design of the light pen system for the realization of self-calibration and self reparation when one light source is deficit for any reason. A self-calibration algorithm is set up through simulation calculations. The error of light pen system is less than 0.1 mm when the coordinate error of point source is ±0.1 mm. An original way of frequency-recognition that applies light source of different modulation frequencies on the light pen is put forward to identify multi point sources.