Patent ID: 9677874
Date: 2017-06-13
CPC Classifications: G01B,G01D,G03F

Claim:
1. A position-measuring device, comprising: at least one first scale and at least one second scale, which are arranged end-to-end to form an enlarged measurement range; and a scanning unit having a light source configured to emit a light beam, wherein the first scale includes a reflective phase grating having first periodic marks which diffract an incident light beam into a predetermined diffraction order with a first diffraction efficiency, and wherein the second scale includes a reflective phase grating having second periodic marks that differ in shape from the first periodic marks, a reflectivity of the phase grating of the second scale being reduced compared to a reflectivity of the phase grating of the first scale to such an extent that the phase grating of the second scale diffracts the incident light beam into the predetermined diffraction order with the first diffraction efficiency.