Design of a Laser Autocollimator-based Optical Sensor with a Rangefinder for Error Correction of Precision Slide Guideways

This paper presents the design and construction of a laser autocollimator-based optical sensor for measurement of the tilt angles of a reflector mounted on the guideways or the moving table of a precision linear slide in the production process of the slide, where the measurement is repeatedly carried out together with a hand scraping operation for correction of the form errors of the slide guideways. Differing from a conventional autocollimator, a laser rangefinder unit is integrated with the autocollimation unit for detection of the positions of the reflector, which is necessary for the efficient error correction of the slide guideways. The autocollimation unit and the rangefinder unit share the same light source for a compact optical design. The optical power of the laser beam is first set to be constant for tilt angles measurement. Then the optical power is modulated with a frequency of 66.7 MHz for measuring the position/distance based on the phase shift method. The resolution of the laser autocollimator is confirmed to be 0.2 arc-second over a range of +/-50 arc-seconds while the measurement positions can be detected with a resolution of 1 mm by the rangefinder, which satisfies the requirements from production of the slide.