Abstract: To improve the laser alignment accuracy of a large unit shafting and reduce the errors caused by position sensitive detector (PSD) that is easily interfered by stray light, a weak signal detection algorithm based on cross-correlation algorithm is proposed, the specific mathematical models are established, and the circuits are designed. The position error compensation of laser alignment instrument for large unit shafting is achieved using the mathematical model of cross-correlation algorithm and circuit. To obtain the data of PSD, a 2-D micro-displacement platform was built to test the system. The repeatability tests were completed using the micro-displacement platform, then the measured data was analyzed. The results indicate that the proposed method can ensure the alignment accuracy of the equipment with the resolution of 0.005 mm, and the anti-noise performance of large unit shafting laser alignment instrument can be effectively improved. Key

Key words: apparatusandintrumentstechnology, laseralignmentinstrument, cross-correlation, weaksignaldetection, errorcompensation