An optical fiber trigger probe and its performance test

HAN Xin, LIN Jiachun
(College of Mechanical Engineering and Applied Electronics Technology，Beijing University of Technology，Beijing 100124，China)

Abstract: In order to solve the problem of the workpiece surface data point sampling of coordinate measuring machine and other precise instruments,the photoelectric technology and digital signal processing(DSP) technology were utilized to develop an optical fiber trigger probe. After the analysis of working principle of an optical fiber trigger probe,it was found that when the light beam was irradiated to the surface of the ball, the light intensity coupled into the receiving optical fibers distributed around the launching optical fiber was changed under the incident angle changed.Based on this phenomenon,a silicon PIN photodiode was adapted to transfer light intensity variation into electrical signal at the end of the receiving optical fibers.After the signal preprocessing,multiple signals’ analogtodigital conversion was conducted;then DSP was used to process the acquired signals,and a trigger pulse signal was sent out when operational results reached a threshold.Finally experiments were designed to test the predisplacement and the undirectional repeatability.Experiments indicate that the predisplacement is 097 μm, and the unidirectional repeatability is 0.42 μm. The experimental results show that the probe is practical for measuring machines.
Key words: optical fiber probe；photoelectric conversion；digital signal processing(DSP)