A diffraction grating online detection device

Abstract

The present invention discloses an online detection device for a diffraction grating, which relates to the field of optical processing, and includes a diffraction grating, a light source, a beam splitter, and a prism. The diffraction grating is provided with a grooved surface, the grooved surface is provided with a grooved line, and a grating angle is provided between the grooved line and the reference surface; the light emitted by the light source is divided into three beams of parallel light by a beam splitter, the beam splitter is perpendicular to the reference surface, and the two reflection surfaces of the prism are also perpendicular to the reference surface. The present invention arranges grooved lines on the diffraction grating, divides the light source into three parallel light beams by a beam splitter, utilizes two diffracted lights generated by the first light beam on the diffraction grating, and the second light beam and the third light beam generate a first reflected light and a second reflected light under the action of the prism reflection surface, and compares the propagation direction of the diffracted light with the propagation direction of the reflected light, so as to accurately judge the relationship between the grating groove direction and the reference surface, and utilizes a novel optical path design to realize the function of accurately positioning the diffraction grating.

Description

Technical Field

[0001] The invention relates to the technical field of optical processing, and in particular to an online detection device for a diffraction grating. Background Art

[0002] Diffraction gratings have a large number of important applications in the fields of optical spectrum analysis, optical communication systems, AR / VR display technology, etc. During the processing and installation of diffraction gratings, the direction of the grating grooves needs to be accurately positioned, and the commonly used positioning method is not easy to realize the online detection function, affecting the cost, efficiency and other comprehensive performance of the product. In order to solve the detection of diffraction gratings, Chinese patent number CN102706542A "A method for detecting the diffraction wavefront of a concave diffraction grating" discloses: establishing a concave diffraction grating diffraction wavefront detection system and installing components in the system, thereby realizing the wavefront detection of the diffraction grating, but this detection method can only realize the behavior before detection, and cannot realize the online real-time detection of the diffraction grating, and the interferometer required by the invention is expensive, and it costs a high cost in after-sales and maintenance.

[0003] Therefore, in order to address the above-mentioned problems, further reduce the manufacturer's production costs and facilitate the online detection of diffraction gratings, the present invention uses a newly designed online detection device to detect the direction of the groove lines and utilizes a novel optical path design to achieve the function of precise positioning of the grating. Summary of the invention

[0004] (1) Technical issues to be resolved

[0005] The present invention aims at the above-mentioned problems in the prior art and, in order to make up for the deficiencies of the prior art, provides an online detection device for two diffraction gratings which can be reasonably manufactured and used.

[0006] (2) Technical solution

[0007] In order to achieve the above technical objectives, the present invention provides such a diffraction grating online detection device, comprising a diffraction grating, a light source, a beam splitter, and a prism, wherein the diffraction grating is provided with a grooved surface, the grooved surface is provided with a grooved line, and a grating angle is provided between the grooved line and the reference surface; the light emitted by the light source is split into three beams of parallel light via the beam splitter, and the three beams of parallel light are respectively a first light beam, a second light beam, and a third light beam;

[0008] The first light beam is incident on the grooved surface of the diffraction grating to generate -1st order diffraction light and +1st order diffraction light, and the second light beam and the third light beam are incident on two reflection surfaces of the prism to generate first reflected light and second reflected light respectively;

[0009] The beam splitter is perpendicular to the reference plane, the two reflecting surfaces of the prism are also perpendicular to the reference plane, and the beam splitter is composed of two light splitting elements.

[0010] Preferably, when the grating angle is 90°, the direction of the groove line is exactly perpendicular to the reference surface.

[0011] Preferably, the two beam splitting elements are respectively a first beam splitting element and a second beam splitting element, and the first beam splitting element and the second beam splitting element are made of birefringent crystal YVO4.

[0012] (3) Beneficial effects

[0013] The present invention overcomes the problems in the prior art that the function of online real-time detection of the diffraction grating cannot be performed, and that the detection requires the use of expensive instruments, which leads to increased costs. The present invention arranges groove lines on the diffraction grating, divides the light source into three parallel light beams through a beam splitter, utilizes two diffracted lights generated by the first light beam on the diffraction grating, and the second light beam and the third light beam generate the first reflected light and the second reflected light under the action of the prism reflection surface, and compares the propagation direction of the diffracted light with the propagation direction of the reflected light, thereby accurately judging the relationship between the grating groove direction and the reference surface, and utilizing the novel optical path design to realize the function of accurately positioning the diffraction grating. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0015] Figure 1 It is a schematic diagram of the optical paths of three beams of flat light after being reflected and diffracted respectively in the diffraction grating online detection device of the present invention;

[0016] Figure 2 for Figure 1 Component distribution structure diagram in top view;

[0017] Figure 3 is a schematic diagram of the structure between the diffraction grating and the reference surface;

[0018] Figure 4 A structural diagram showing the formation of three parallel lights by the light source inside the beam splitter;

[0019] Figure 5 for Figure 4 Propagation view of three parallel lights in the state.

[0020] Figure numerals: diffraction grating 101, groove line 102, reference plane 103, grating angle 104, light source 200, first light beam 210, second light beam 220, third light beam 230, beam splitter 201, prism 202, -1 order diffraction light 209, +1 order diffraction light 211, first reflected light 221, second reflected light 231, 301-first beam splitting element, 302-second beam splitting element. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0022] Example:

[0023] See also Figure 1-5 As shown, a diffraction grating online detection device according to the present invention comprises a diffraction grating 101, a light source 200, a beam splitter 201, and a prism 202. The diffraction grating 101 is provided with a grooved surface, the grooved surface is provided with a grooved line 102, and a grating angle 104 is provided between the grooved line 102 and a reference surface 103; the light emitted by the light source 200 is divided into three beams of parallel light by the beam splitter 201, and the three beams of parallel light are respectively a first light beam 210, a second light beam 220, and a third light beam 230; the first light beam 210 is incident on the grooved surface of the diffraction grating 101 to generate a -1st order diffraction light 209 and a +1st order diffraction light 211, and the second The light beam 220 and the third light beam 230 are incident on the two reflecting surfaces of the prism 202, and generate the first reflected light 221 and the second reflected light 231 respectively; the beam splitter 201 is perpendicular to the reference surface 103, and the two reflecting surfaces of the prism 202 are also perpendicular to the reference surface 103, and the beam splitter 201 is composed of two splitting elements; when the grating angle 104 is 90°, the direction of the groove line 102 is precisely perpendicular to the reference surface 103; the two splitting elements are the first splitting element 301 and the second splitting element 302, and the first splitting element 301 and the second splitting element 302 are made of birefringent crystal YVO4.

[0024] During use of the present invention, a reference plane 103 is first set. The reference plane 103 can be the side of the diffraction grating 101 or other surfaces in the present device, depending on the reference in practice. In most application scenarios, the grating angle 104 is set to 90°, so that the direction of the groove line 102 can be accurately perpendicular to the reference plane 103. The present invention is explained by taking the grating angle of 90° as an example: using the two beam splitting elements 301 and 302 in the beam splitter 201, the first beam splitting element 301 is used to separate the incident light source 200 into two beams of parallel light in the vertical direction, one beam does not deviate from the original incident path, and the other first beam 210 is offset downward and propagates in a parallel direction. The second beam splitting element 302 then splits the light beam that does not deviate from the original incident path into two beams of parallel light in the horizontal direction, wherein the second beam 220 propagates along the original incident path, and the other beam 230 is offset to the left and propagates in a parallel direction (see for details). Figure 5 ); The spectroscopic elements 301, 302 can be made of birefringent crystals such as YVO4, or can be made of polished optical glass coated with a suitable spectroscopic film. The process is well known in the industry and will not be described here.

[0025] The three parallel light beams transmitted from the beam splitter 201 are the first light beam 210, the second light beam 220 and the third light beam 230, respectively. The first light beam 210 is incident on the groove surface of the diffraction grating to generate -1 order diffraction light 209 and +1 order diffraction light 211; the second light beam 220 and the third light beam 230 are incident on the two reflection surfaces of the prism 202 respectively, and the first reflected light 221 and the second reflected light 231 are generated respectively. The two reflecting surfaces of the prism 202 are perpendicular to the reference surface, and from the basic principles of diffraction physics, it can be concluded that: 1. The second light beam 220 and the third light beam 230 are reflected by the prism 202 to generate the first reflected light 221 and the second reflected light 231, and the difference vector of their propagation direction vectors is parallel to the reference surface 103; 2. The first light beam 210 is incident on the diffraction grating 101, and the difference vector of the propagation direction vectors of the generated -1 order diffraction light 209 and +1 order diffraction light 211 is perpendicular to the direction of the groove line 102 on the diffraction grating 101.

[0026] By measuring the propagation direction of the +1st order diffraction light 211 and the -1st order diffraction light 209 in real time and comparing them with the propagation direction of the first reflected light 221 and the second reflected light 231, it is possible to accurately determine whether the grating groove direction is perpendicular to the reference surface. Figure 1 As shown, the direction of the groove line 102 of the diffraction grating 101 is rotated and adjusted in real time until the groove direction is precisely perpendicular to the reference surface.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A diffraction grating online detection device, characterized in that: The invention comprises a diffraction grating (101), a light source (200), a beam splitter (201), and a prism (202); the diffraction grating (101) is provided with a grooved surface, the grooved surface is provided with a grooved line (102), and a grating angle (104) is provided between the grooved line (102) and a reference surface (103); light emitted by the light source (200) is split into three beams of parallel light via the beam splitter (201), the three beams of parallel light being respectively a first light beam (210), a second light beam (220), and a third light beam (230); The first light beam (210) is incident on the grooved surface of the diffraction grating (101) to generate -1st order diffraction light (209) and +1st order diffraction light (211), and the difference vector between the propagation direction vectors of the two is perpendicular to the direction of the groove line (102) on the diffraction grating (101); the second light beam (220) and the third light beam (230) are incident on the two reflection surfaces of the prism (202), and respectively generate a first reflected light (221) and a second reflected light (231), and the difference vector between their propagation direction vectors is parallel to the reference surface (103); The beam splitter (201) is perpendicular to the reference surface (103), the two reflection surfaces of the prism (202) are also perpendicular to the reference surface (103), and the beam splitter (201) is composed of two light splitting elements; by measuring the propagation directions of the +1-order diffraction light (211) and the -1-order diffraction light (209) in real time and comparing them with the propagation directions of the first reflected light (221) and the second reflected light (231), it is determined whether the grating groove direction is perpendicular to the reference surface (103).

2. The diffraction grating online detection device according to claim 1, characterized in that: When the grating angle (104) is 90°, the direction of the groove line (102) is perpendicular to the reference surface (103).

3. A diffraction grating online detection device according to claim 1 or 2, characterized in that: The two beam splitting elements are respectively a first beam splitting element (301) and a second beam splitting element (302); the first beam splitting element (301) and the second beam splitting element (302) are made of birefringent crystal YVO4.

Images