Laser alignment techniques for simultaneously measuring five degree-of-freedom deviations of the object

An optical measurement system has been developed for the simultaneous detection for five degree-of-freedom (DOF) deviations of the object. The measuring system design is based on laser holographic technique, laser alignment technique, laser drift compensation technique and magneto-optic modulating technique where a single laser beam is used as datum line. It carries out the automatic testing in a deformation of machine tool, or the loaded axon in a strain wind tunnel balance. Through actual calibration and measurement, the resolution of the system is estimated to be 4 μm for linear displacement error measurement and better than 2 sec for angular error measurement with a 1 m offset between laser and a photoelectric receiving target.