Optical positioning device

摘要

#CMT# #/CMT# The device has a detection unit (26) for recording a set of positionally dependent phase-shifted scanning signals, where partial beams of rays propagating in direction of a scanning unit (20) undergo superposition, and are deflected by a beamsplitter element (22) in a direction of the detection unit, after impinging on a measuring graduation (11). A scanning graduation (24) induces focusing of the rays from the measuring graduation at a reflector element (25) to recollimate the rays propagated in a direction of the measuring graduation, after being reflected at the reflector element. #CMT# : #/CMT# The beam splitter element is a grating beam splitter element. The reflector element is mirror. The detecting unit is an optoelectronic detector. The measuring graduation is a one-dimensional linear graduation. #CMT#USE : #/CMT# Optical position-measuring device for high-resolution sensing of relative position of a scanning unit and a measuring standard. #CMT#ADVANTAGE : #/CMT# The scanning gratings can be arranged as planar diffractive lenses that can be manufactured more precisely and less expensively than refractive lenses. The device comprises a ring lens that influences only the deflected partial beams of rays so as to eliminate the need for illuminating and counter-propagating a superimposed beam to pass through the same lens along an optical axis such that collimating an illuminating beam on the optical axis producing substantial wavefront aberrations can be prevented as the ring lens is specially optimized to the focusing of obliquely incident component beams, thus permitting a separate influencing of a central beam and the obliquely deflected component beams, and hence minimizing wavefront aberrations of the device. The optimized selection of the phase response of the ring lens in the scanning graduation, and the optimal selection of other parameters of the device allow high installation, operating and manufacturing tolerances on a part of the device. The device ensures that a pulsed operation of a semiconductor laser diode can ensure a measurement instant that is precisely determined in time, so that a short pulse duration shortens coherence length of the semiconductor laser diode so as to suppress the interference from interfering beams. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a schematic view of an optical position measuring device. 11 : Measuring graduation 20 : Scanning unit 22 : Beamsplitter element 24 : Scanning graduation 25 : Reflector element 26 : Detection unit.