Patent ID: 11860057
Assignee: CHANGCHUN INSTITUTE OF OPTICS, FINE MECHANICS AND PHYSICS, CHINESE ACADEMY OF SCIENCES
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A heterodyne one-dimensional grating measuring device, comprising:
a light source;
a reading head;
a photoelectric receiving module; and
a signal processing device;
wherein the light source is configured to generate two beams of linearly polarized light having characteristics of overlapping, polarization orthogonal, and fixed frequency difference; the two beams of linearly polarized light are respectively a first polarized light having a frequency of fA and a second polarized light having a frequency of fB, the first polarized light is a first S polarized light, and the second polarized light is a first P polarized light;
the reading head is configured to receive the first polarized light and the second polarized light, the first polarized light and the second polarized light are respectively incident on a surface of a moving one-dimensional measuring grating to generate a +1-order diffracted light and a −1-order diffracted light, both the +1-order diffracted light and the −1-order diffracted light comprise a first polarized light component and a second polarized light component, the +1-order diffracted light and the −1-order diffracted light are respectively incident to the photoelectric receiving module through the reading head;
the photoelectric receiving module is configured to receive the +1-order diffracted light and the −1-order diffracted light to form two paths of beat frequency signals; wherein one path is a beat frequency signal having a frequency of fB-fA where the beat frequency having the frequency of fB-fA is formed by interfering the second polarized light component of the −1-order diffracted light with the first polarized light component of the +1-order diffracted light; another path is a beat frequency signal having a frequency of fB-fA where the beat frequency signal having the frequency of fB-fA is formed by interfering the first polarized light component of the −1-order diffracted light with the second polarized light component of the +1-order diffracted light; and
the signal processing device is configured to perform differential calculation on the two paths of the beat frequency signals to realize a displacement measurement of single diffraction of the one-dimensional measuring grating for four-fold optical subdivision.