Patent Document ID: 4195425
Application ID: 05866908
Patent Status: 1

Claim One:
1. In a system for measuring the relative position and/or movement in magnitude and direction of an object being without special optical markers thereon, said object being measured with respect to a reference by using at least an imaging system, at least one grating positioned at least in the vicinity of the image plane of said imaging system and coordinated with at least one measuring direction and photoelectric detectors associated with said grating and generating electrical signals according to light fluxes emanating from said grating, the improvement comprising: forming by said imaging system in a first and/or at least in a second measuring direction an image each of said object and said reference respectively on said grating in positions spatially separated, said images of said object and said reference differing from one another in image scale and perspective caused by different object distance and different reference distance respectively from said grating; generating for each measuring direction according to the interaction between said images and said grating electrical A.C. signals, the frequencies of which differ in dependence upon said different image scale and said perspective and being proportional to the relative position and/or movement of said object to be measured; and evaluating said electrical A.C. signals by employing the trigonometrical relationships of said image scale and said perspective for producing signals indicating the position and the movement of said object, said trigonometrical relationships of said image scale being defined by the ratio image size/object size, said trigonometrical relationships of said perspective being defined by the depiction of spatially extended objects on a plane surface.