Sampling and interpolation for photoelectric measuring system - using modulated beam directed through movable measuring raster

摘要

The photoelectric path and angle measuring system, for a machine tool or measuring instr., uses carrier frequency sampling and interpolation of the path and angle information. A light source modulated by the signal from a HF generator, is used to illuminate a measuring raster, which is movable relative to the light source and to a photodetector array lying on the opposite side of it. The light source uses two LED's respectively controlled by the sin and cos functions of the HF generator signal. The photodetectors are coupled in pairs to two operational amplifiers and selective filters for forming amplitude modulated signals which are cos or sin functions of the path or angle information. The filters are coupled to a summing amplifier connected via an A/D converter to a digital phase evaluation device.