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 1:
2. The heterodyne one-dimensional grating measuring device according to claim 1, wherein the reading head comprises a reflecting mirror, a polarized beam splitting prism, a first quarter wave plate, a second quarter wave plate, a compensating mirror plated with a reflecting film, a reflecting prism, and a refracting lens;
wherein the reflecting mirror is disposed on an emergent light path of the light source, the reflecting mirror is configured to vertically reflect the first polarized light and the second polarized light to the surface of the one-dimensional measuring grating, so as to generate the +1-order diffracted light and the −1-order diffracted light;
the refracting lens is disposed on a diffracted light path of the one-dimensional measuring grating, the refracting lens is configured to refract the +1-order diffracted light and the −1-order diffracted light, so that the +1-order diffracted light and the −1-order diffracted light are parallel to each other and are vertically incident to the polarized beam splitting prism;
the polarized beam splitting prism is disposed on a transmission light path of the refracting element, the polarized beam splitting prism is configured to respectively reflect 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, the polarized beam splitting prism is further configured to respectively transmit 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;
the first quarter wave plate is disposed on a reflected light path of the polarized beam splitting prism, the first quarter wave plate is configured to respectively convert the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light into left-handed polarized light, then the left-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 respectively perform 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, so that the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light become a second P polarized light after passing through the first quarter wave plate, then the second P polarized light is incident to the polarized beam splitting prism;
the second quarter plate is disposed on a transmission light path of the polarized beam splitting prism, the second quarter plate is configured to respectively convert the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light into right-handed polarized light, then the right-handed polarized light is incident to the compensating mirror;
the compensating mirror is disposed on a transmission light path of the second quarter wave plate, the compensating mirror is configured to reflect the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light, so that the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light become a second S polarized light after passing through the second quarter wave plate, then the second S polarized light is incident to the polarized beam splitting prism;
the polarized beam splitting prism is further configured to transmit 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 photoelectric receiving module after the first polarized light component of the +1-order diffracted light and the first polarized light component of the −1-order diffracted light become the second P polarized light, and the polarized beam splitting prism is further configured to reflect 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 photoelectric receiving module after the second polarized light component of the +1-order diffracted light and the second polarized light component of the −1-order diffracted light become the second S polarized light.