Design of Highly Accurate Linear Carriage Guided by Laser Beam Straight Datum and Its Application for Profile Measurement and Machining

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Using the directional stabilized laser beam as a physical straight datum, instead of the tangible reference surface, a method is proposed for the measurement of an error motion of a slide table and/or surface profile of mechanical components.By the computer simulation based on diffraction theory, it is confirmed that a laser beam oscillated from a stable set of resonance mirrors, even if they have surface irregularity or misalignment, can be used for the stable straight datum.Combining a two-dimensional position sensor/compensator, which comprises QPD and piezo actuator, for laser beam center and piezo-driven mirrors compensator for the position and angular fluctuation of beam path, a directional stabilizer for a laser beam is so designed as to stabilize the fluctuation smaller than 2*10^<-8> rad.Using the stabilized laser beam as a straight datum, a linear carriage with the position sensor/compensator is so designed and built as to move along the stabilized laser beam with working distance of 1m and error motion less than 100nm.By mounting the displacement sensor on the linear carriage, surface profile measuring machine is designed with the motional accuracy equivalent to the stability of the laser beam straight datum.