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 6:
7. The heterodyne one-dimensional grating measuring device according to claim 1, wherein the reading head comprises a polarized beam splitting prism, a first quarter wave plate, a second quarter wave plate plated with a reflecting film and a reflecting prism;
the polarized beam splitting prism is disposed on an emergent light path of the light source, the polarized beam splitting prism is configured to receive the first polarized light and the second polarized light, transmit the second polarized light to the first quarter wave plate, and reflect the first polarized light to the second quarter wave plate;
the first quarter wave plate is disposed on a transmission light path of the polarized beam splitting prism, the first quarter wave plate is configured to convert the second polarized light into right-handed polarized light, then the right-handed polarized light is incident to the reflecting prism;
the reflecting prism is disposed on a transmission light path of the first quarter wave plate, the reflecting prism is configured to reflect the second polarized light, 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;
the second quarter wave plate is disposed on a reflected light path of the polarized beam splitting prism, the second quarter wave plate is configured to convert the first polarized light into left-handed polarized light, the left-handed polarized light is reflected through the reflecting film, then passes through the second quarter wave plate again to become a third P polarized light, and then returns to the polarized beam splitting prism; and
the polarized beam splitting prism is further configured to transmit the first polarized light after the first polarized light becomes the third P polarized light, reflect the second polarized light 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 the one beam combined of the first polarized light and the second polarized light is diffracted to generate the −1-order diffracted light and the +1-order diffracted light.