A tilted cemented holographic grating

Abstract

The present application relates to the technical fields of micro-nano information optical grating, and a tilted cemented holographic grating, comprising a prism light guide element, a grating substrate and a volume holographic grating layer arranged on the grating substrate; the volume holographic grating layer has a periodic refractive index modulation structure, and the volume holographic grating layer is connected with the prism light guide element in a tilted cemented manner; the incident light propagating through the prism light guide element is incident on the volume holographic grating layer in a direction satisfying or close to the Bragg matching condition, and is diffracted by the volume holographic grating layer; the present application is provided with the volume holographic grating layer, which is independently prepared on the planar grating substrate, and is cut and then connected with the prism light guide element in a tilted cemented manner, thereby avoiding the technical difficulty of directly coating and exposing the volume holographic grating on the prism inclined surface with a large base angle, and the exposure light path arrangement is more flexible, which is conducive to improving the preparation quality and batch consistency.

Description

Technical Field

[0001] This invention relates to the field of micro-nano information optical grating technology, specifically a tilted cementitious holographic grating. Background Technology

[0002] The performance of a spectrometer largely depends on its dispersive elements. Whether using prisms or gratings alone, they all exhibit nonlinear dispersion. In traditional optical paths, if both prisms and gratings are used simultaneously, a large space must be left between them to adjust the optical path. Prisms and gratings physically integrate the two, eliminating the connection space and making their dispersive characteristics complementary. This significantly improves dispersive nonlinearity, resulting in a more uniform distribution of light of different wavelengths on the detector surface. At the same time, it greatly reduces the size and weight of the instrument and reduces energy loss and stray light interference caused by long-distance propagation of light in the air.

[0003] The typical structure of existing volume holographic gratings is a sandwich bonding structure with two symmetrical prisms sandwiching the volume holographic grating in the middle. However, the above structure has the following technical problems: First, the traditional sandwich bonding structure usually requires three bonding layers, which is complicated in manufacturing process and has many bonding interfaces, increasing the size and weight of the device and also increasing the impact of the bonding layers on the optical path. Moreover, the more bonding layers there are, the higher the risk of bonding interface aging and delamination during long-term use, affecting the reliability of the device. Second, the existing volume holographic gratings have a single structural form, which is difficult to flexibly adjust according to different optical path designs and installation spaces. There is a lack of a volume holographic grating structure that can be fabricated in a controllable and highly adaptable manner.

[0004] Therefore, a tilted adhesive holographic grating is needed to solve the problems raised in the background art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an inclined cemented holographic grating, which solves the technical problems of high difficulty in directly fabricating volume holographic gratings on the inclined surface of a prism with a large base angle, and the limited structural forms of existing volume holographic gratings.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a tilted cemented holographic grating, comprising a prism light guide element, a grating substrate, and a volume holographic grating layer disposed on the grating substrate; the volume holographic grating layer has a periodic refractive index modulation structure, and the volume holographic grating layer is tiltedly cemented to the prism light guide element; the incident light propagated through the prism light guide element is incident on the volume holographic grating layer in a direction that satisfies or is close to the Bragg matching condition, and is diffracted and dispersed by the volume holographic grating layer.

[0007] Preferably, it further includes an encapsulation glass, which is bonded to the surface of the volume holographic grating layer away from the grating substrate. The grating substrate, the volume holographic grating layer, and the encapsulation glass together form a parallelogram volume holographic grating assembly with a sandwich structure. The parallelogram volume holographic grating assembly is bonded to the prism light guide element through one surface of the encapsulation glass.

[0008] Preferably, the prism light guide element is a trapezoidal prism, and the bottom surface of the trapezoidal prism is bonded to the surface of the encapsulating glass; the incident surface and the exit surface of the trapezoidal prism are respectively coated with an anti-reflection film.

[0009] Preferably, the prism light guide element is an isosceles triangular prism or a right-angle triangular prism; the volume holographic grating layer is bonded to the encapsulation glass to form an encapsulated volume holographic grating structure, or the volume holographic grating layer is not encapsulated with the encapsulation glass to form an unencapsulated volume holographic grating structure; the grating substrate and the volume holographic grating layer thereon are inclined relative to the prism light guide element so that the incident light guided by the prism light guide element satisfies the Bragg incident condition of the target working band.

[0010] Preferably, the prism light guide element, the grating substrate, and the encapsulation glass are all made of optically transparent materials, including but not limited to high-refractive-index optical glass, quartz glass, crystalline materials, transparent ceramic materials, synthetic diamond, transparent resin or other optical polymer materials, glass-ceramic materials, gradient refractive index materials, and organic-inorganic composite transparent materials; the incident and exit surfaces of the prism light guide element are coated with antireflection films, which are used to improve the transmittance in the working wavelength band and reduce interface reflection stray light.

[0011] Preferably, the prism light guide element, the grating substrate, and the encapsulation glass are all made of H-ZF52 flint glass.

[0012] Preferably, the material of the volume holographic grating layer includes, but is not limited to, photopolymers, dichromate gelatin, silver halide holographic recording materials, or photorefractive materials.

[0013] Preferably, the material of the volume holographic grating layer is a photopolymer.

[0014] Preferably, the working scene of the tilted cemented holographic grating covers the visible to near-infrared band, and achieves high-efficiency -1st order diffraction near the center wavelength.

[0015] A method for preparing a tilted adhesive holographic grating includes the following steps: Step 1: Fabricate a volume holographic grating layer with a periodic refractive index modulation structure on a planar grating substrate; Step 2: According to the encapsulation requirements, the volume holographic grating layer is bonded to the encapsulation glass to form an encapsulated volume holographic grating assembly, or it can be retained as a non-encapsulated volume holographic grating assembly. Step 3: Cut the volume holographic grating assembly into a parallelogram volume holographic grating structure; Step four: The cut parallelogram-shaped holographic grating structure is assembled with the prism light guide element at a predetermined tilt angle and bonded together with optical adhesive to form an integral structure, so that the incident light after propagation through the prism light guide element is incident on the volume holographic grating layer in a direction that satisfies or is close to the Bragg matching condition.

[0016] This invention provides an inclined adhesive holographic grating. It has the following beneficial effects: 1. This invention incorporates a volume holographic grating layer, which is independently fabricated on a planar grating substrate and then cut and tiltedly bonded to a prism light guide element. This avoids the process difficulties of directly coating and exposing the volume holographic grating on the inclined surface of a prism with a large base angle. The exposure light path arrangement is more flexible, which is beneficial to improving the preparation quality and batch consistency.

[0017] 2. The present invention uses a trapezoidal prism and parallelogram holographic grating assembly. In the main embodiment, the asymmetric combination structure of trapezoidal prism and parallelogram holographic grating assembly is adopted, which requires only two adhesive layers, reduces the number of adhesive interfaces, effectively reduces the overall thickness and weight of the device, and shortens the optical path, thereby reducing light energy loss and stray light interference.

[0018] 3. This invention incorporates a prism light guide element, which can be a trapezoidal prism, an isosceles triangular prism, or a right-angle triangular prism. The volume holographic grating assembly can be either encapsulated or unencapsulated, allowing for flexible adaptation to different incident light angles and spectrometer spatial layout requirements. The incident light is incident on the volume holographic grating layer in a direction that satisfies or closely approximates the Bragg matching condition, resulting in highly efficient diffraction of the incident light in the target working wavelength band. This invention is suitable for high-resolution, miniaturized spectrometers. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an inclined adhesive holographic prism according to a main embodiment of the present invention; Figure 2 This is a schematic diagram of the method flow of the present invention; Figure 3 This is a schematic diagram of another trapezoidal prism tilted adhesive structure of the present invention; Figure 4 This is a schematic diagram of the isosceles triangular prism encapsulated inclined adhesive structure of the present invention; Figure 5 This is a schematic diagram of the non-encapsulated inclined adhesive structure of the isosceles triangular prism of the present invention. Figure 6 This is a schematic diagram of the right-angled triangular prism encapsulated inclined adhesive structure of the present invention; Figure 7 This is a schematic diagram of the non-encapsulated inclined adhesive structure of the right-angled triangular prism of the present invention; Figure 8 This is the diffraction efficiency curve of the -1 diffraction order in the non-polarized state, which is the main embodiment of the present invention.

[0020] Among them, 1. Antireflective coating; 2. Trapezoidal prism; 3. Encapsulation glass; 4. Volume holographic grating layer; 5. Grating substrate; 6. Isosceles triangular prism; 7. Right-angle triangular prism. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see the appendix Figure 1 -Appendix Figure 8 This invention provides an inclined adhesive holographic grating, comprising an inclined adhesive holographic grating with a trapezoidal prism 2 and a parallelogram-shaped volume holographic grating assembly as its main structures. The grating includes an antireflective film 1, a trapezoidal prism 2, an encapsulating glass 3, a volume holographic grating layer 4, and a grating substrate 5. The volume holographic grating layer 4 is fabricated on one side surface of the grating substrate 5. After the encapsulating glass 3 is bonded to the grating substrate 5, the volume holographic grating layer 4 is encapsulated between the two, forming a sandwich-structured parallelogram-shaped volume holographic grating assembly. The parallelogram-shaped volume holographic grating assembly is then bonded to the trapezoidal prism 2 to form an integral inclined adhesive holographic grating.

[0023] like Figure 1 As shown, in this embodiment, the trapezoidal prism 2, the grating substrate 5, and the encapsulation glass 3 are all made of optical glass material with a refractive index n. d The refractive index is approximately 1.84666. Using optical glass materials with the same or similar refractive index helps reduce reflection loss and optical path deflection error when light propagates at different optical interfaces, thereby improving the optical stability of the combined device. The incident and exit surfaces of the trapezoidal prism 2 are coated with antireflection films 1. The antireflection film 1 can be a single-layer magnesium fluoride film, a multilayer dielectric antireflection film, or other antireflection film systems suitable for the target working wavelength band. By coating the incident and exit surfaces with antireflection films, the light transmittance in the working wavelength band can be improved, and stray light caused by interface reflection can be reduced, which helps to improve the energy utilization rate and imaging signal-to-noise ratio of the spectrometer system.

[0024] like Figure 3 As shown, the volume holographic grating layer 4 is made of photopolymer material with an average refractive index of 1.5 and a refractive index modulation degree of 0.021. The grating period of the volume holographic grating layer 4 is 555 nm, the thickness is 16 μm, and the grating fringe tilt angle is 87.2°. Under these parameters, the volume holographic grating can better satisfy the Bragg matching condition, so that the incident light near the center wavelength can obtain a high diffraction efficiency.

[0025] In this embodiment, the volume holographic grating layer 4 can be prepared by holographic interference exposure. Specifically, the grating substrate 5 is first cleaned and dried to remove dust, oil, and organic contaminants from its surface. Then, a photopolymer material is coated or attached to the surface of the grating substrate 5 to form a recording layer to be exposed. Then, two coherent recording beams are used to generate interference fringes inside the photopolymer material. By controlling the angle between the two recording beams, the incident direction, and the exposure dose, a volume phase grating structure with a predetermined period and fringe tilt angle is recorded inside the photopolymer material. After exposure, the photopolymer material is cured according to the process requirements of the selected photopolymer material to stabilize its internal refractive index modulation structure, thereby obtaining the volume holographic grating layer 4 prepared on the grating substrate 5.

[0026] like Figure 3 and Figure 4 As shown, after the volume holographic grating layer 4 is fabricated, the encapsulation glass 3 is aligned with the grating substrate 5 so that the volume holographic grating layer 4 is located between the grating substrate 5 and the encapsulation glass 3. Then, optical adhesive is used to fix the encapsulation glass 3 to the grating substrate 5, and then it is cut to form a parallelogram volume holographic grating structure. This structure can encapsulate and protect the volume holographic grating layer 4, reduce the impact of moisture, dust and mechanical contact in the external environment on the grating layer, and improve the stability and reliability of the device during long-term use.

[0027] Furthermore, the prepared parallelogram-shaped holographic grating is assembled and bonded to the trapezoidal prism 2. During the assembly process, the corresponding bonding surfaces of the encapsulation glass 3 and the trapezoidal prism 2 are made to fit together, and the spatial position of the volume holographic grating layer 4 relative to the trapezoidal prism 2 is ensured to meet the design optical path requirements. Optical adhesive is used for bonding, preferably an optical adhesive with high transmittance, low curing shrinkage, and good refractive index matching, in order to reduce the influence of the bonding layer on the light propagation direction and diffraction efficiency. After bonding is completed, the device can be cured and cleaned to finally obtain an integral tilted bonded holographic grating.

[0028] When the combined device of the present invention is in operation, the beam to be split first enters from the incident surface of the trapezoidal prism 2, and after being refracted by the trapezoidal prism 2 and the encapsulating glass 3, it is incident on the volume holographic grating layer 4 in a direction close to the Bragg angle. Since the volume holographic grating layer 4 has a periodic refractive index modulation structure, when the incident light meets the Bragg matching condition, the incident light will undergo high-efficiency diffraction within the volume holographic grating layer 4. The diffracted light then exits through the grating substrate 5, realizing the dispersive splitting of the incident light.

[0029] In this embodiment, a volume holographic grating layer 4 is first fabricated on a planar grating substrate 5, and then a parallelogram-shaped volume holographic grating is formed by encapsulating glass 3. Finally, it is bonded to a trapezoidal prism 2 to form an integral structure. This method reduces the process difficulty of directly exposing and recording volume holographic gratings on complex prism inclined surfaces and improves the operability and parameter controllability in the fabrication process of volume holographic gratings. At the same time, the sandwich encapsulation structure can effectively protect the volume holographic grating layer 4 and enhance the mechanical strength and environmental stability of the device.

[0030] like Figure 1 and Figure 3 As shown, in Embodiment 1: the prism light guide element is still a trapezoidal prism 2, but the volume holographic grating layer 4 is directly disposed on the grating substrate 5 without encapsulation glass; this structure can be used in applications with higher requirements for device thickness, weight, or the number of bonding interfaces. Figure 3 In the case, the incident and exit surfaces of the trapezoidal prism 2 are also coated with anti-reflection film 1 to improve transmittance and reduce stray light.

[0031] like Figure 4 and Figure 5 As shown, in Embodiment 2: the prism light guide element is an isosceles triangular prism 6, and the volume holographic grating layer 4 is located between the encapsulation glass 3 and the grating substrate 5 to form an encapsulated volume holographic grating assembly; the assembly is connected to the isosceles triangular prism 6 through an inclined adhesive surface. This structure can use the isosceles triangular prism to guide the incident light and adapt to different incident angles and installation space requirements. Figure 4 In the middle, the incident and exit surfaces of the isosceles triangular prism 6 are coated with antireflective coatings 1.

[0032] like Figure 4 and Figure 5 As shown, in embodiment three: the prism light guiding element is an isosceles triangular prism 6, the volume holographic grating layer 4 is disposed on the grating substrate 5, and no encapsulation glass is disposed. This structure maintains the light guiding function of the isosceles triangular prism while reducing the encapsulation glass and corresponding bonding interface, and is suitable for scenarios that require lightweight structure and compact optical path. Figure 5 In the middle, the incident and exit surfaces of the isosceles triangular prism 6 are coated with antireflective coatings 1.

[0033] like Figure 6 and Figure 7As shown, in embodiment four: the prism light guide element is a right-angled triangular prism 7, and the volume holographic grating layer 4 is located between the encapsulation glass 3 and the grating substrate 5, forming an encapsulated volume holographic grating assembly. Figure 6 In the middle, the incident surface and the exit surface of the right-angled triangular prism 7 are respectively coated with anti-reflection film 1.

[0034] like Figure 6 and Figure 7 As shown in Embodiment 5: the prism light guide element is a right-angled triangular prism 7, the volume holographic grating layer 4 is disposed on the grating substrate 5, and no encapsulation glass is provided; this structure can further simplify the structure while ensuring the prism light guiding and volume holographic grating diffraction and beam splitting functions. Figure 7 In the middle, the incident surface and the exit surface of the right-angled triangular prism 7 are respectively coated with anti-reflection film 1.

[0035] The above Figures 3 to 7 The structures shown are all extended embodiments based on the main structure of this invention. Their common features are: they all adopt a structure in which a prism light guide element and a volume holographic grating assembly are bonded together; they all change the propagation direction of the incident light through the prism light guide element and make the incident light enter the volume holographic grating layer 4 in a direction that satisfies or is close to the Bragg matching condition; the prism type and whether or not to set the encapsulation glass in different embodiments can be selected according to the target working band, the spatial layout of the spectrometer, the beam incident conditions and the processing and assembly requirements.

[0036] Specifically, the prism light guide element, the grating substrate 5, and the encapsulation glass 3 can be made of optical glass, quartz glass, crystalline materials, or transparent resin materials; as a preferred embodiment, the prism light guide element, the grating substrate 5, and the encapsulation glass 3 are all made of H-ZF52 flint glass, with a refractive index n d Approximately 1.84666; Using materials with the same or similar refractive index helps to reduce reflection loss and optical path deflection error when light propagates at different optical interfaces, thereby improving the optical stability of the combined device.

[0037] The volume holographic grating layer 4 can be prepared using photopolymer, dichromate gelatin, silver halide holographic recording material, photorefractive material, or other transparent photosensitive recording material capable of forming a volume phase grating. As a preferred embodiment, the volume holographic grating layer 4 is a photopolymer film layer with an average refractive index of 1.5 and a refractive index modulation of 0.021.

[0038] The grating period, thickness, and fringe tilt angle of the volume holographic grating layer 4 are designed according to the target operating wavelength and Bragg matching conditions. Generally, the grating period is 500-2000 nm, the thickness is 2-100 μm, and the grating fringe tilt angle is 0°-90°. As a preferred embodiment, the grating period is 555 nm, the thickness is 16 μm, and the grating fringe tilt angle is 87.2°.

[0039] like Figure 1 and Figure 3 As shown in Example 6: In this example, the trapezoidal prism 2, the grating substrate 5, and the encapsulation glass 3 are all made of H-ZF52 flint glass; the volume holographic grating layer 4 is a photopolymer film layer with an average refractive index of 1.5, a refractive index modulation degree of 0.021, a grating period of 555nm, a thickness of 16μm, and a grating fringe tilt angle of 87.2°; both the incident and exit surfaces of the trapezoidal prism 2 are coated with an antireflection film 1, and the encapsulation glass 3 and the surface of the volume holographic grating layer 4 away from the grating substrate 5 are... The grating substrate 5, the volume holographic grating layer 4, and the encapsulation glass 3 are bonded together to form a parallelogram-shaped volume holographic grating assembly. This assembly is bonded to the trapezoidal prism 2 through one side surface of the encapsulation glass 3. When light with a center wavelength of 730 nm is incident on the volume holographic grating layer 4 at an angle that satisfies the Bragg condition, the combined device can achieve high-efficiency -1st order diffraction near the center wavelength. Experiments show that the diffraction efficiency of this device in the 670-780 nm operating band can approach or reach 80%.

[0040] like Figure 2 As shown, the present invention also provides a method for preparing an inclined adhesive holographic grating, comprising the following steps: Step 1: A volume holographic grating layer 4 with a periodic refractive index modulation structure is prepared on a planar grating substrate 5. Specifically, the grating substrate 5 is first cleaned and dried. Then, a volume holographic grating material is coated or attached to the surface of the grating substrate 5 to form a recording layer to be exposed. Then, using a two-beam holographic interference exposure method, by controlling the angle between the two recording beams, the incident direction, and the exposure dose, a volume phase grating structure with a predetermined grating period, thickness, and fringe tilt angle is recorded inside the recording material. After exposure, a curing process is performed to stabilize the refractive index modulation structure.

[0041] Step 2: According to the encapsulation requirements, the volume holographic grating layer 4 is bonded to the encapsulation glass 3 to form an encapsulated volume holographic grating assembly, or it can be retained as a non-encapsulated volume holographic grating assembly. For the encapsulated structure, the encapsulation glass 3 and the grating substrate 5 are aligned so that the volume holographic grating layer 4 is located between the two, and the encapsulation glass 3 and the grating substrate 5 are fixedly connected using optical adhesive.

[0042] Step 3: Cut the volume holographic grating assembly into a parallelogram volume holographic grating structure. According to the design size and angle requirements, use mechanical cutting or laser cutting to cut the glued assembly into a parallelogram.

[0043] Step 4: The cut parallelogram-shaped holographic grating structure is assembled with the prism light guide element at a predetermined tilt angle and bonded together with optical adhesive to form an integral structure, so that the incident light after propagation through the prism light guide element is incident on the volume holographic grating layer 4 in a direction that satisfies or is close to the Bragg matching condition.

[0044] like Figure 8 As shown, in the non-polarized state, the -1 diffraction order diffraction efficiency curve of the tilted cemented holographic grating of the present invention in the 670-780nm working band indicates that the diffraction efficiency of the device near the center wavelength can approach or reach 80%. This shows that the tilted cemented holographic grating of the present invention can achieve high-efficiency spectral dispersion while maintaining a compact structure, and is suitable for high-resolution, miniaturized spectrometers and related optical spectral dispersion systems.

[0045] Based on the above technical solution, this embodiment of the invention also provides a working principle of a tilted cemented holographic grating, comprising the following: the incident light to be split first enters the prism light guide element, and after being refracted by the prism, changes its propagation direction to meet or approach the Bragg matching condition of the volume holographic grating layer 4, and is incident on the volume holographic grating layer 4; the volume holographic grating layer 4 has a periodic refractive index modulation structure inside, and its grating period, thickness and fringe tilt angle are pre-designed according to the target working band, so that the incident light of the center wavelength undergoes high-efficiency diffraction when the Bragg condition is met. In the diffracted light, the -1st order diffracted light is emitted at different angles according to different wavelengths, thereby realizing dispersive spectral splitting; the diffracted light of other orders or light that does not meet the Bragg condition propagates in the original direction or other directions; the beam after diffraction and splitting is emitted through the grating substrate 5 and enters the subsequent optical system to complete the spectral detection.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A tilted adhesive holographic grating, characterized in that, It includes a prism light guide element, a grating substrate (5), and a volume holographic grating layer (4) disposed on the grating substrate (5); the volume holographic grating layer (4) has a periodic refractive index modulation structure, and the volume holographic grating layer (4) is inclinedly bonded to the prism light guide element; the incident light after propagation through the prism light guide element is incident on the volume holographic grating layer (4) in a direction that satisfies or is close to the Bragg matching condition, and is diffracted and split by the volume holographic grating layer (4).

2. The inclined adhesive holographic grating according to claim 1, characterized in that, It also includes an encapsulation glass (3), which is bonded to the side surface of the volume holographic grating layer (4) away from the grating substrate (5). The grating substrate (5), the volume holographic grating layer (4) and the encapsulation glass (3) together form a parallelogram volume holographic grating assembly with a sandwich structure. The parallelogram volume holographic grating assembly is bonded to the prism light guide element through one side surface of the encapsulation glass (3).

3. The inclined adhesive holographic grating according to claim 2, characterized in that, The light guiding element of the prism is a trapezoidal prism (2), and the trapezoidal prism (2) is bonded to the surface of the encapsulation glass (3); the incident surface and the exit surface of the trapezoidal prism (2) are respectively coated with anti-reflection film (1).

4. The inclined adhesive holographic grating according to claim 1, characterized in that, The prism light guide element is an isosceles triangular prism (6) or a right-angle triangular prism (7); the volume holographic grating layer (4) is bonded to the encapsulation glass (3) to form an encapsulated volume holographic grating structure, or the volume holographic grating layer (4) is not encapsulated with the encapsulation glass to form a non-encapsulated volume holographic grating structure; the grating substrate (5) and the volume holographic grating layer (4) on it are inclined relative to the prism light guide element so that the incident light guided by the prism light guide element meets the Bragg incident condition of the target working band.

5. The inclined adhesive holographic grating according to claim 4, characterized in that, The prism light guide element, the grating substrate (5), and the encapsulation glass (3) are all made of optically transparent materials, including but not limited to high refractive index optical glass, quartz glass, crystal materials, transparent ceramic materials, artificial diamond, transparent resin or other optical polymer materials, glass ceramic materials, gradient refractive index materials, and organic-inorganic composite transparent materials; the incident and exit surfaces of the prism light guide element are coated with antireflection films (1), which are used to improve the transmittance in the working band and reduce interface reflection stray light.

6. The inclined adhesive holographic grating according to claim 5, characterized in that, The prism light guide element, the grating substrate (5), and the encapsulation glass (3) are all made of H-ZF52 flint glass.

7. The inclined adhesive holographic grating according to claim 1, characterized in that, The materials of the volume holographic grating layer (4) include, but are not limited to, photopolymers, dichromate gelatin, silver halide holographic recording materials, or photorefractive materials.

8. The inclined adhesive holographic grating according to claim 7, characterized in that, The material of the volume holographic grating layer (4) is a photopolymer.

9. A tilted adhesive holographic grating according to claim 8, characterized in that, The tilted cemented holographic grating operates in a scene covering the visible to near-infrared bands and achieves high-efficiency -1st order diffraction near the center wavelength.

10. A method for preparing an inclined adhesive holographic grating, applied to the inclined adhesive holographic grating of any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Prepare a volume holographic grating layer (4) with a periodic refractive index modulation structure on a planar grating substrate (5). Step 2: According to the encapsulation requirements, the volume holographic grating layer (4) is bonded to the encapsulation glass (3) to form an encapsulated volume holographic grating assembly, or it is retained as a non-encapsulated volume holographic grating assembly; Step 3: Cut the volume holographic grating assembly into a parallelogram volume holographic grating structure; Step 4: The cut parallelogram holographic grating structure is assembled with the prism light guide element at a predetermined tilt angle and bonded together with optical glue to form an integral structure, so that the incident light after propagation through the prism light guide element is incident on the volume holographic grating layer (4) in a direction that satisfies or is close to the Bragg matching condition.

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