Improvement of metrological characteristics of the laser pattern generators with circular scanning mode by the use of hybride angular encoder

The error of positioning in the angular direction caused by the limited accuracy of the angular encoder is rather specific and typical only for laser pattern generators containing a rotation unit. The error of this encoder is particularly important for formation of topology of angle measuring structures, such as angular rasters, limbs, scales, or multibit code disks, and for synthesis of topology of arbitrarily shaped diffractive optical elements, especially at large radii. The method of improvement the accuracy of laser pattern generator with circular scanning is proposed. The result is achieved by using hybrid angular encoder in it. Its use allows measurements of the turning angle and current radial deflections of the angular coordinate laser pattern generator rotor axis simultaneously. For that, two measuring patterns: radial raster for measuring angular displacement and ring for measuring linear shift raster in a tangential direction are formed on a single glass basis for one technological process.