Two-dimensional pupil-expanding optical waveguide aiming device based on polarization holographic grating

Abstract

The two-dimensional pupil-expanding optical waveguide aiming device comprises a light source, a reticle and an optical waveguide, the reticle is located between the optical waveguide and the light source, and a reticle pattern is arranged on the reticle; the optical waveguide comprises a waveguide medium, a coupling-in polarization body holographic lens and a coupling-out two-dimensional pupil-expanding structure, the coupling-in polarization body holographic lens and the coupling-out two-dimensional pupil-expanding structure are located in the waveguide medium, the coupling-out two-dimensional pupil-expanding structure comprises at least two polarization body holographic gratings, and the upper layers of the polarization body holographic gratings and the coupling-in polarization body holographic lens are made of chiral liquid crystal materials. The lower layer is a photo-induced orientation material, the surface of the photo-induced orientation material coupled into the polarizer holographic lens is a parabolic phase profile, and the coupled polarizer holographic lens couples and collimates a light beam with a pattern formed by the light source irradiating the reticle and then emits the light beam to the coupled-out two-dimensional pupil expanding structure; the coupling-out two-dimensional pupil expanding structure carries out light beam expansion on the received pattern in the two-dimensional direction and then carries out coupling-out. The system is large in visual field, high in resolution and small in size.

Description

TECHNICAL FIELD

[0001] The present application relates to sighting devices, in particular to a two-dimensional pupil expanding optical waveguide sighting device based on polarization volume holographic grating. BACKGROUND

[0002] As an important component of devices that need to be aimed, the performance of the sighting scope directly affects the accuracy and effect of the device. The existing sighting scope technology, such as telescopic sighting scope, red dot sighting scope and holographic sighting scope, has advantages and disadvantages, but still has some limitations in practical application. For example, although the telescopic sighting scope provides a high magnification field of view, it has a narrow field of view and is heavy; the red dot sighting scope and the holographic sighting scope are suitable for rapid aiming, but they depend on batteries and have high cost. Therefore, the existing sighting scope technology has deficiencies in the field of view, resolution and weight. SUMMARY

[0003] In view of the problems existing in the prior art, the purpose of the present application is to provide a two-dimensional pupil expanding optical waveguide sighting device based on polarization volume holographic grating with a large field of view, high resolution and small volume.

[0004] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical scheme:

[0005] A two-dimensional pupil expanding optical waveguide sighting device based on polarization volume holographic grating, comprising a light source, a reticle and an optical waveguide, the reticle being located between the optical waveguide and the light source, the reticle being provided with a reticle pattern, the optical waveguide comprising a waveguide medium and a coupling-in polarization volume holographic lens and a coupling-out two-dimensional pupil expanding structure located in the waveguide medium, the coupling-out two-dimensional pupil expanding structure comprising at least two polarization volume holographic gratings, the polarization volume holographic gratings and the upper layer of the coupling-in polarization volume holographic lens both being chiral liquid crystal materials, and the lower layer of the polarization volume holographic gratings and the coupling-in polarization volume holographic lens both being photo-alignment materials, the photo-alignment material surface of the coupling-in polarization volume holographic lens being a parabolic phase profile, the coupling-in polarization volume holographic lens coupling in and collimating the patterned light beam formed by the light source irradiating the reticle and then emitting it to the coupling-out two-dimensional pupil expanding structure, and the coupling-out two-dimensional pupil expanding structure expanding the received pattern in two-dimensional direction and then coupling out.

[0006] Further, the grating vector sum of the coupling-in polarization volume holographic lens and the polarization volume holographic grating of the coupling-out two-dimensional pupil expanding structure is zero.

[0007] Further, the coupling-out two-dimensional pupil expanding structure is L-shaped, comprising a turning polarization volume holographic grating and an out polarization volume holographic grating, the turning polarization volume holographic grating expanding the light beam in the first dimension direction and turning the light beam out to the out polarization volume holographic grating, and the out polarization volume holographic grating expanding the light beam in the second dimension direction and then coupling out.

[0008] Further, the cross-type out-coupling two-dimensional pupil expanding structure includes at least two polarization volume holographic gratings with different grating vector directions, and all the polarization volume holographic gratings are stacked at the same position of the waveguide to realize beam expansion and out-coupling in two-dimensional directions.

[0009] Further, the included angle between the in-coupling polarization volume holographic lens and the grating vector of the turning polarization volume holographic grating is equal to the included angle between the grating vector of the turning polarization volume holographic grating and the out-coupling polarization volume holographic grating.

[0010] Further, the diffraction angles of the in-coupling polarization volume holographic lens and the out-coupling two-dimensional pupil expanding structure are greater than the critical angle of total reflection of the waveguide medium.

[0011] Further, the LED light source is a red-green point or area light source without a display pattern.

[0012] Further, the reticle pattern is dynamically adjusted by adjusting the relative angle of the light source and the optical waveguide.

[0013] Further, the reticle pattern includes a point, a line, a circle, and a concentric circle.

[0014] Further, the in-coupling polarization volume holographic lens and the out-coupling two-dimensional pupil expanding structure respond to a red-green waveband.

[0015] Compared with the prior art, the present application has the following beneficial effects: the in-coupling structure utilizes the polarization volume holographic lens to collimate the light emitted by the LED light source and guide the parallel light beam into the waveguide structure for transmission, without the need for a collimating lens, thus simplifying the structure; the out-coupling structure utilizes the excellent polarization diffraction characteristics of the polarization volume holographic grating to realize pupil expansion of the optical waveguide, making the structure of the sighting device more compact, and the grating can perform dispersion compensation, reducing the influence of wavelength drift of the light source, supporting a red-green dual-color light source, and achieving parallax-free, and supporting dynamic adjustment of the reticle pattern when adjusting the incident angle of the light machine. The technology has the advantages of high transparency, low distortion, wide field of view, high resolution, low power consumption, and light weight, is suitable for various combat environments, and improves the shooting accuracy and combat effectiveness. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a structural schematic diagram of a two-dimensional pupil expanding optical waveguide sighting device based on a polarization volume holographic grating provided in an embodiment of the present application;

[0017] Figure 2 FIG. 3 is a schematic diagram of a polarization volume holographic lens orientation material surface of a two-dimensional pupil expanding optical waveguide sighting device based on a polarization volume holographic grating provided in an embodiment of the present application;

[0018] Figure 3This is a schematic diagram of the L-shaped coupling two-dimensional pupil expansion structure provided in the embodiment of the present invention in the xy plane;

[0019] Figure 4 This is a schematic diagram of the cross-type coupled two-dimensional pupil expansion structure provided in the embodiment of the present invention in the xy plane. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0021] This invention provides a two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating, such as... Figure 1 As shown, it includes a light source 1, a reticle 2, and an optical waveguide 3.

[0022] Light source 1 is an LED light source, which is a red and green dot or area light source without a display pattern. The wavelength range of green light is 525±10nm, and the wavelength range of red light is 625±10nm. The mid-range brightness of red light is >900 nits, the mid-range brightness of green light is >2200 nits, the high-range brightness of red light is >13000 nits, and the high-range brightness of green light is >30000 nits.

[0023] The reticle 2 is located between the optical waveguide 3 and the light source 1, and the reticle has a reticle pattern. The reticle pattern shapes include arrows (green), two dots (green), crosses (green), outer rings (green), and inner rings (red). The reticle pattern can be dynamically adjusted by adjusting the relative angle between the LED light source 1 and the optical waveguide 3.

[0024] The optical waveguide 3 includes a waveguide medium and a coupled polarizer holographic lens 31 and a coupled two-dimensional pupil expander structure 32 located within the waveguide medium. The coupled two-dimensional pupil expander structure 32 includes at least two polarizer holographic gratings. The coupled polarizer holographic lens 31 couples and collimates the patterned light beam formed by the light source illuminating the reticle, then emits it to the coupled two-dimensional pupil expander structure 32. The coupled two-dimensional pupil expander structure 32 expands the received patterned light beam in two dimensions and then couples it out, allowing it to enter the human eye. A polarizer holographic grating is a grating structure based on liquid crystal molecules. Structurally and in principle, it can be considered a combination of volume holographic grating and polarizer grating diffraction mechanisms. Under the Bragg condition, this structure can produce single-order diffracted light with high diffraction efficiency, i.e., it exhibits a volume effect and shows different responses to the polarization of the incident light. This invention utilizes the excellent polarization diffraction characteristics of a polarizing holographic grating to achieve an expansion of the exit pupil of the optical waveguide, making the structure of the sight more compact. This results in advantages such as parallax-free and lightweight design, while also reducing the impact of light source wavelength drift, eliminating dispersion, and supporting dynamic adjustment of the reticle pattern.

[0025] Both the upper layer of the polarizer holographic grating and the coupled polarizer holographic lens 31 are made of chiral liquid crystal material, and the lower layer is made of photo-alignment material. The surface of the photo-alignment material of the coupled polarizer holographic lens 31 has a parabolic phase profile. Figure 2 As shown.

[0026] The diffraction angles of the coupled polarizing holographic lens 31 and the coupled two-dimensional pupil expander structure 32 are greater than the critical angle for total internal reflection of the waveguide medium, and the response band covers the red and green bands. Thus, multi-band total internal reflection is achieved.

[0027] The coupled two-dimensional pupil expander structure 32 is L-shaped or cross-shaped. The grating vector sum of the coupled polarizer holographic lens 31 and the coupled two-dimensional pupil expander structure 32 polarizer holographic grating is zero, and there is no effect of dispersion or wavelength drift.

[0028] like Figure 3 The diagram shows a schematic of an L-shaped coupled two-dimensional pupil expansion structure 32, including a folding polarizer holographic grating 321 and an exit polarizer holographic grating 322. The two gratings are in different spatial positions. The angle between the grating vectors of the coupled polarizer holographic lens and the folding polarizer holographic grating, as well as the angle between the grating vectors of the folding polarizer holographic grating and the exit polarizer holographic grating, are equal. The folding polarizer holographic grating 321 expands the beam in the first dimension and redirects the beam to the exit polarizer holographic grating 322. The exit polarizer holographic grating 322 then expands the beam in the second dimension before coupling it out. This results in a two-dimensional expanded exit pupil.

[0029] like Figure 4 The diagram shows a cross-type coupled two-dimensional pupil expander structure 32, comprising at least two polarizer holographic gratings with different grating vector directions. All polarizer holographic gratings are stacked vertically at the same position on the waveguide. The cross-type coupled two-dimensional pupil expander structure 32 can first deflect the beam propagating within the waveguide medium, thereby changing the beam's propagation path. Simultaneously, when the beam re-enters the grating after the deflection, it can be led out of the waveguide, thus achieving pupil expansion and coupled output functions. Compared to the L-type coupled two-dimensional pupil expander polarizer holographic grating, the cross-type structure reduces the grating area, resulting in higher space utilization. While achieving two-dimensional pupil expansion, it also reduces the size and weight of the waveguide.

[0030] It should be understood that the embodiments and descriptions above are only the principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating, characterized in that: The system includes a light source, a reticle, and an optical waveguide. The reticle is located between the optical waveguide and the light source and has a reticle pattern. The optical waveguide includes a waveguide medium and a coupled polarizer holographic lens and a coupled two-dimensional pupil expander structure located within the waveguide medium. The coupled two-dimensional pupil expander structure includes at least two polarizer holographic gratings. The upper layer of both the polarizer holographic gratings and the coupled polarizer holographic lens is a chiral liquid crystal material, and the lower layer is a photo-aligned material. The surface of the photo-aligned material of the coupled polarizer holographic lens has a parabolic phase profile. The coupled polarizer holographic lens couples and collimates the patterned light beam formed by the light source illuminating the reticle before emitting it to the coupled two-dimensional pupil expander structure. The coupled two-dimensional pupil expander structure couples the received patterned light beam out after expanding it in two dimensions.

2. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 1, characterized in that: The sum of the grating vectors of the coupled polarizer holographic lens and the coupled two-dimensional pupil-expanding structure polarizer holographic grating is zero.

3. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 2, characterized in that: The coupled two-dimensional pupil expansion structure is L-shaped, including a flex polarizer holographic grating and an exit polarizer holographic grating. The flex polarizer holographic grating expands the beam in the first dimension and then rotates the beam out to the exit polarizer holographic grating. The exit polarizer holographic grating expands the beam in the second dimension and then couples it out.

4. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 2, characterized in that: The coupled two-dimensional pupil expansion structure is of the cross type, including at least two polarizing holographic gratings with different grating vector directions. All polarizing holographic gratings are stacked one on top of the other at the same position on the waveguide, so as to realize the beam expansion and coupling out in two-dimensional direction.

5. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 3, characterized in that: The angle between the grating vectors of the coupled polarizer holographic lens and the fold polarizer holographic grating, and the angle between the fold polarizer holographic grating and the exit polarizer holographic grating are equal.

6. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 1, characterized in that: The diffraction angles of the coupled polarizing holographic lens and the coupled two-dimensional pupil expander structure are greater than the critical angle of total internal reflection of the waveguide medium.

7. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 1, characterized in that: The LED light source is a red and green dot or surface light source without a display pattern.

8. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 1, characterized in that: The reticle pattern is dynamically adjusted by regulating the relative angle between the light source and the optical waveguide.

9. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 1, characterized in that: The dividing pattern includes dots, lines, circles, and concentric circles.

10. The two-dimensional pupil-expanding optical waveguide aiming device based on a polarizing holographic grating according to claim 1, characterized in that: The coupled polarizer holographic lens and coupled two-dimensional pupil expander structure have response bands covering the red and green bands.

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