The Laser Shaft Alignment System with Dual PSDsJIAO Guohua 1,2 ,LI Yulin1,ZHANG Dongbo3,LI Tonghai1,HU Baowen1 (1.Xian Institute of Optics and Precision Mechanics of CAS,Xi'an 710068,China; 2.Graduate School of the Chinese Academy of Sciences,Beijing 100039,China; 3.The 16th Institute of CATEC,Xi'an 710100,China)Shaft alignment is an important technique during installation and maintenance of a rotating machine. A high-precision laser alignment system has been designed with dual PSDs (Position Sensing Detector) to change traditional manual way of shaft alignment and to make the measurement easier and more accurate. The system is comprised of two small measuring units (laser transmitter and detector) and a PDA (Personal Digital Assistant) with the measurement software. The laser alignment system with dual PSDs was improved on a single PSD system,and it gets higher measurement accuracy than the previous design,and it has been succeeded in designing and implement for actual shaft alignment. In the system,the range of offset measurement is ±4 mm,and the resolution is 1.5 μm,and the accuracy is less than 2 μm.rotating machine; shaft alignment; laser alignment; position sensing detector (PSD); laser micro-displacement measurement