Application of laser displacement sensor to free-form surface measurement

By taking a point displacement laser as an object, this paper researches the application of the sensor to free-form surface measurement. In consideration of the measurement error of the laser displacement sensor due to the inclination of the measuring point, a quantifiable inclination error model was proposed to improve the measuring accuracy. On the basis of the principle of direct-point laser triangulation start, the geometric relationship of the laser light paths was analyzed. According to the shift of convergent light spot centroid, the inclination error model was derived. Following that, the laser displacement sensor was calibrated with a high precision laser interferometer and a sine bar, the measured data by the laser displacement sensor were compensated by the error model, and the measurement accuracy was significantly improved. Finally, the experimental measurement on an aspheric lens surface was performed, the free-form surface inclination measuring point was calculated and the measurement data were corrected by the proposed model. Experimental results show that inclination quantization error model has controlled the measurement error of the laser displacement sensor by less than 10 μm, which meets the requirements of the free surface measurements by laser displacement sensors. ©, 2015, Chinese Academy of Sciences. All right reserved.