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 7:
8. The heterodyne one-dimensional grating measuring device according to claim 7, wherein the reading head further comprises a refracting lens and a third quarter wave plate;
wherein 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 third quarter wave plate;
the third quarter wave plate is disposed on a transmission light path of the refracting element, the third quarter wave plate is configured to 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 the third S polarized light, the third S polarized light is vertically incident to the polarized beam splitting prism; the third quarter wave plate is further configured to 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 the third P polarized light, the third P polarized light is vertically incident to the polarized beam splitting prism;
the polarized beam splitting prism is configured to 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 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 configured to 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 the left-handed polarized light, then the left-handed polarized light is incident to the reflecting prism;
the reflecting prism is configured to 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 to the first quarter wave plate to become a fourth P polarized light, then the fourth P polarized light is incident to the polarized beam splitting prism again and is transmitted to the photoelectric receiving module through the polarized beam splitting prism;
the second quarter wave plate is configured to 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 the right-handed polarized light, then the right-handed polarized light is reflected through the reflecting film again and passes through the second quarter wave plate to become a fourth S polarized light, and the fourth S polarized light is incident to the polarized beam splitting prism and then is reflected to the photoelectric receiving module through the polarized beam splitting prism.