A new five-degree-of-freedom measuring system was developed as a linear guide. According to the principle of
autocollimation, the system consisted of two semiconductor lasers, two right angle prisms, two lenses, two polarization
spectroscopes and four quadrant Si-photoelectric detectors(QPD). Two axial displacements and three angular rotation
degrees are measured by comparing the position of the spot center on the QPD. Repetitive simulations show that the
accuracy of the system is 3" for measurement of angle, which proves the feasibility of this system. The advantages of the
system include simple structure, easy operation, high accuracy, low cost and real-time work.