A non-contact calibration system for step gauges using automatic collimation techniques

To calibrate transfer standards for length calibration, a non-contact calibration system for step gauges and gauge blocks has been developed, in which a laser interferometer was equipped to obtain the length displacement and dual-stage driving-position techniques were used to carry step gauges to approach the measuring location. A non-contact collimation technique combined with an optoelectronic microscope was proposed for achieving identification. The optoelectronic microscope eliminates both the contact deformation resulting from the mechanical force and motion deviations. The combination of dual-stage driving-position techniques and the non-contact collimation technique can ensure that the collimation repeatability is less than 20 nm. The experimental tests and comparison results indicated that the non-contact strategy and dual-stage position techniques can provide a reliable method for building a length calibration system for gauges, industrial line scales, and end bars.