TRANSDUCER OF LINEAR MOVEMENTS Russian patent published in 1995 - IPC

FIELD: measurement technology. SUBSTANCE: condenser, pass two-coordinate diffraction grating made with two systems of lines arranged crosswise which zone of crossing has shape of square and is fabricated in the form of central group and four groups of lines placed in pairs and in series with reference to it, reflection two-coordinate grating attached to object, collecting lenses and photodetectors mounted in focuses of lenses are positioned in sequence in path of optical radiation. In pass diffraction grating line is displaced in symmetry relative to central group correspondingly by 1/8 and 3/8 of part of period of reflection grating and has shape of rectangle with dimensions equal to half of square formed by zone of crossing of lines. Lenses are installed accordingly behind each group of lines and are manufactured in shape similar to shape of group of lines. In case of duel opposite placement of photodetectors in specified pairs there are formed two photoelectric signals not containing constant component shifted through 90 deg for each measured coordinate which is accomplished by subtraction of signals formed by beams reflected from one and the same area of reflection diffraction grating. It leads to more accurate compensation of constant component and does not effect operation of next stage of signal processing. EFFECT: improved compensation of constant component, expanded application field. 3 dwg