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 18:
19. The heterodyne one-dimensional grating measuring method according to claim 13, wherein the step S2 specifically comprises the following steps:
S201′: incidenting the first polarized light and the second polarized light to a polarized beam splitting prism of the reading head, transmitting the second polarized light to a first quarter wave plate of the reading head through the polarized beam splitting prism, and reflecting the first polarized light to a second quarter wave plate of the reading head through the polarized beam splitting prism;
S202′: converting the second polarized light into right-handed polarized light through the first quarter wave plate, then incidenting the right-handed polarized light to the reflecting prism; reflecting the second polarized light through a reflecting prism, so that the second polarized light passes through the first quarter wave plate to become a third S polarized light and then returns to the polarized beam splitting prism; converting the first polarized light into left-handed polarized light through the second quarter wave plate, reflecting the left-handed polarized light through the reflecting film to pass through the second quarter wave plate again to become a third P polarized light, and then the third P polarized light returns to the polarized beam splitting prism;
S203′: further transmitting the first polarized light through the polarized beam splitting prism after the first polarized light becomes the third P polarized light, reflecting the second polarized light through the polarized beam splitting prism after the second polarized light becomes the third S polarized light, so that the first polarized light and the second polarized light are combined into one beam to be incident on the surface of the one-dimensional measuring grating, and diffracting the one beam combined of the first polarized light and the second polarized light to generate the −1-order diffracted light and the +1-order diffracted light;
S204′: refracting the −1-order diffracted light and the +1-order diffracted light through a refracting lens of the reading head, so that the −1-order diffracted light and the +1-order diffracted light are parallel to each other and are vertically incident to a third quarter wave plate of the reading head;
S205′: converting the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light into a fourth S polarized light through the third quarter wave plate, vertically incidenting the fourth S polarized light to the polarized beam splitting prism; converting the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light into a fourth P polarized light through the third quarter wave plate, vertically incidenting the fourth P polarized light to the polarized beam splitting prism;
S206′: reflecting the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light to the first quarter wave plate through the polarized beam splitting prism; transmitting the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light to the second quarter wave plate through the polarized beam splitting prism;
S207′: converting the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light into the left-handed polarized light through the first quarter wave plate, then incidenting the left-handed polarized light to the reflecting prism; performing secondary reflection on the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light to the first quarter wave plate to become a fifth P polarized light through the reflecting prism, then incidenting the fifth P polarized light to the polarized beam splitting prism again and transmitting the fifth P polarized light to the photoelectric receiving module through the polarized beam splitting prism; converting the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light into the right-handed polarized light through the second quarter wave plate, then reflecting the right-handed polarized light through the reflecting film again and passing through the second quarter wave plate to become a fifth S polarized light, and incidenting the fifth S polarized light to the polarized beam splitting prism and then reflecting the S polarized light to the photoelectric receiving module through the polarized beam splitting prism.