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 12:
13. A heterodyne one-dimensional grating measuring method, comprising following steps:
S1: generating two beams of linearly polarized light having characteristics of overlapping, polarization orthogonal, and fixed frequency difference through a light source, where 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;
S2: respectively entering the first polarized light and the second polarized light into a reading head, refracting the first polarized light and the second polarized light through the reading head, and respectively incidenting the first polarized light and the second polarized light on a surface of an one-dimensional measuring grating to generate +1-order diffracted light and −1-order diffracted light where both the +1-order diffracted light and the −1-order diffracted light comprise a first polarized light component and a second polarized light component; then respectively incidenting the +1-order diffracted light and the −1-order diffracted light to a photoelectric receiving module through the reading head;
S3: receiving the +1-order diffracted light and the −1-order diffracted light through the photoelectric receiving module, interfering the second polarized light component of the −1-order diffracted light with the first polarized light component of the +1-order diffracted light to form a beat frequency signal having a frequency of fB-fA, and interfering the first polarized light component of the −1-order diffracted light with the second polarized light component of the +1-order diffracted light to form a beat frequency signal having a frequency of fB-fA;
S4: performing differential calculation on two paths of the beat frequency signals through a signal processing device to realize a displacement measurement of single diffraction of the one-dimensional measuring grating for four-fold optical subdivision.