Patent ID: 7154609
Filing Date: 2006-12-26
Classification: G01D

Abstract:
1. An interferential position measuring arrangement for determining the relative positions of a first object and a second object which are movable with respect to each other at least in a measuring direction, comprising: a light source connected to a first object, which emits a beam of rays in a direction of an optical axis; an optical element arranged downstream of said light source, which converts said beam of rays emitted by said light source into an incoming beam of rays; a scale grating connected to a second object that moves relative to said first object and arranged downstream of said light source, which splits said incoming beam of rays at least into: a second scanning grating that is arranged in a beam path of said second partial beam of rays and causes splitting of said second partial beam of rays into fifth and sixth partial beams of rays, wherein at least two of said third, fourth, fifth and sixth partial beams of rays meet again, and wherein in the case of relative movement between said scale grating and said light source, a periodically modulated interferential fringe pattern with a definite spatial interferential fringe pattern period results in a detection plane; a detection arrangement arranged in said detection plane, which causes splitting of light entering through said detection arrangement into at least three different spatial directions; and optoelectronic detector elements arranged in said at least three spatial directions for detecting phase-shifted scanning signals wherein said first scanning grating and said second scanning grating are arranged together on a scanning plate, wherein said scanning plate is opaque in areas exclusive of said first and second scanning gratings so that only partial beams according to a +1