Application of area CMOS image processing for 2-D optoelectronic autocollimator

To meet the increasing requirement for small angle measurement in the field of military and industry, the authors had designed the 2-D optoelectronic autocollimator based on area CMOS image sensor to pursuit higher precision and stability. For hardware circuit, the authors chose the DSP+FPGA structure to build a reliable and high-speed platform. For software algorithms, frame subtraction, Gaussian and Median filtering were effective to reduce the noise of original images. After threshold segmentation, weighted centroid locating algorithm was selected to calculate the sub-pixel location for laser spot. Finally, angle conversion was performed to get the 2-D misalignment angles. Experimental results show that, with the help of the methods of 2-D image processing, the autocollimator can obtain high precision within 0.2" and the capability of anti-interference for misalignment angle measuring.