APPLICATION OF FOCUSED LASER BEAM IN LINEAR ENCODER

摘要

The idea of high resolution (0,01μm) displacement encoder with laser diode light beam focused on the scale surface is presented. Due to application of the focused laser beam the acceptable tilts of the encoder head relative to the grating in the prototype device reach about of 0,5 are degree in all directions and the tolerance of the distance between head and the grating is equal to about 0.1 mm. A new simple reference point detection method that use a scale grating edge as an reference point has been proposed. This technique allows significant reduction of noniinearity errors of the measuring system. Noniinearity of the prototype device does not exceed 0,1μm in 48 mm measuring range.