Holographic sighting telescope based on volume Bragg grating
By employing reflective and transmissive volume Bragg gratings and photothermal refractive glass materials in the holographic sight, combined with a beam expander and an off-axis parabolic reflector, the problem of light source wavelength drift is solved, improving the accuracy and stability of the sight and reducing its size.
Patent Information
- Application Number
- CN202520053239.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2035-01-09
AI Technical Summary
The semiconductor light source in existing holographic sights experiences wavelength drift due to changes in external temperature, causing displacement of the holographic sight and affecting aiming accuracy and stability. At the same time, the system's optical path is limited by the size of the components, making further optimization difficult.
By employing reflective and transmissive volume Bragg gratings as wave-locking elements and holographic reticles, and using photothermal refractive glass material, combined with beam expanders and off-axis parabolic mirrors, the stability of the light source wavelength and angle is achieved, and the optical path structure is shortened.
It effectively suppresses the influence of wavelength drift on the holographic imaging position, improves the accuracy and stability of the scope, enhances the brightness and recognizability of the holographic image, and at the same time reduces the size of the scope, saving assembly space.
Smart Images
Figure CN223582256U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the field of holographic optics, specifically relates to a kind of holographic sighting telescope based on volume Bragg grating. BACKGROUND
[0002] With the emergence and development of laser technology, holography has been greatly promoted and gradually applied to image display, information storage, information encryption and other fields. At the end of the twentieth Century, the emergence of holographic collimator first applied holography to light weapons and showed the performance superior to other types of collimator, it has the advantages such as fast collimation speed, bright field of view, wide field of view, even if the observation window is partially obscured or contaminated can complete collimation work, and has been equipped in the troops of multiple countries.
[0003] Holographic collimator generally faces two problems, one is that the wavelength of light source drifts due to temperature change, and then the holographic collimation mark is displaced;Second, due to the size of the device, the system light path cannot be too large. For the holographic recording element used in traditional holographic collimator, a feasible optimization scheme is proposed in the article "Application of photo-thermo-refractive glass as a holographic medium for holographic collimator gun sights", which uses a volume Bragg grating holographic reticle made of photo-thermo-refractive glass material instead of traditional organic photosensitive holographic recording medium, which has selectivity to the wavelength and incident angle of light source, thereby solving the problem of wavelength drift to a certain extent, and the photo-thermo-refractive glass material has good mechanical stability, thermal stability, chemical stability and high transmittance, so it does not need to be sealed during storage. However, due to the low refractive index modulation of the material, the effective thickness of the grating needs to be increased to improve the diffraction efficiency. In addition, the wavelength of the semiconductor light source of the current holographic collimator drifts with the change of external temperature, thereby causing the displacement of the holographic collimation mark.
[0004] Therefore, the prior art still needs to be improved and developed. UTILITY MODEL CONTENT
[0005] In view of the problems existing in the prior art, the purpose of the utility model is to provide a holographic collimator based on volume Bragg grating, which can improve the accuracy and reliability of the collimator, and aims to solve the problem that the wavelength of the semiconductor light source of the existing holographic collimator drifts with the change of external temperature, thereby causing the displacement of the holographic collimation mark.
[0006] The technical scheme of the utility model is as follows:
[0007] A holographic scope based on volume Bragg grating, wherein the holographic scope comprises a scope shell, an illumination light system and a holographic reticle;
[0008] The illumination light system and the holographic reticle are arranged inside the scope shell.
[0009] The scope shell is provided with a scope window.
[0010] The illumination light system comprises a semiconductor laser, a wave-locking element, a beam expander and an off-axis parabolic reflector.
[0011] The holographic reticle carries a hologram of aiming reticle marks.
[0012] The wave-locking element is a reflective volume Bragg grating, and the holographic reticle is a transmissive volume Bragg grating.
[0013] The light emitted by the semiconductor laser passes through the wave-locking element, the wave-locking element returns the parallel light with an incident angle of 0° to the semiconductor laser cavity to form a resonant wave-lock, the parallel light transmitted by the wave-locking element passes through the beam expander and the off-axis parabolic reflector in sequence to obtain collimated parallel light, and the collimated parallel light is irradiated onto the holographic reticle to form a holographic image of the reticle marks; the aiming reticle marks are reproduced in the direction of the human eye observation, and a virtual image of the reticle marks is generated at a distance close to infinity from the human eye; when the human eye observes through the scope window, the virtual image of the reticle marks is overlapped with the aiming target, and the aiming function is realized.
[0014] Preferably, the materials of the wave-locking element and the holographic reticle are photothermal birefringence glass.
[0015] The wave-locking element and the holographic reticle are two types of volume Bragg gratings, the former is a reflective volume Bragg grating, and the latter is a transmissive volume Bragg grating; both have excellent selectivity for the wavelength and incident angle of light; the material of the volume Bragg grating is photothermal birefringence glass, the wavelength drift coefficient of which reaches 0.01 nm / ℃, and when the wavelength of the light source deviates by 2 nm, the output wavelength deviation can be controlled to 0.067 nm, and at this time, the deviation of the holographic reticle mark image is reduced to 5×10 -3 m, the influence of wavelength drift on the holographic imaging position is effectively suppressed, and the accuracy and stability of the holographic scope are increased; and the photothermal birefringence glass has a high refractive index modulation, which realizes higher holographic diffraction efficiency, makes the displayed holographic image brighter, and has higher recognition degree.
[0016] Preferably, the material of the holographic reticle is photothermal birefringence glass with a refractive index modulation of up to 500 ppm.
[0017] The utility model discloses refractive index regulation system high up to 500ppm's light-induced thermal refractive glass material is used as holographic recording medium, need not increase material thickness, can realize higher diffraction efficiency.
[0018] In addition, the utility model discloses the collimation after the beam expander and off-axis parabolic mirror are expanded to light source, shorten the system light path, effectively reduce the size of holographic sighting telescope, compared with the holographic sighting telescope of existing, size is smaller, and the assembly space is saved.
[0019] Preferably, the size of the holographic sighting telescope is: length L=85~90nm, width W=55nm, height H=65~70nm.
[0020] Preferably, the normal direction of the wave-locking element is placed at 0° with the light direction of the semiconductor laser, so that the parallel light part with 0° incident angle returns to the semiconductor laser cavity to form resonance wave-locking.
[0021] Preferably, the main optical axis of the beam expander is placed parallel to the transmission light direction, and the beam expander is a double-concave lens.
[0022] Preferably, the off-axis parabolic mirror is placed in the emission direction of the beam expander, and the included angle between the irradiation direction of the collimated parallel light and the normal direction of the holographic reticle is 40~80°.
[0023] More preferably, the off-axis parabolic mirror is placed in the emission direction of the beam expander, and the included angle between the irradiation direction of the collimated parallel light and the normal direction of the holographic reticle is 60°. By designing the optical path in this way, the size of the holographic sighting telescope can be as small as possible.
[0024] Preferably, the thickness of the reflective volume Bragg grating is 1~3mm, and the thickness of the transmissive volume Bragg grating is 0.5~3mm. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 It is the optical path structure schematic drawing of prior holographic sighting telescope;
[0026] Figure 2 It is the relationship diagram that the imaging angle deviation of traditional holographic reticle changes with wavelength;
[0027] Figure 3 It is the optical path structure schematic drawing of holographic sighting telescope in the utility model embodiment;
[0028] Figure 4 It is the curve diagram that the selection of volume Bragg grating to angle changes with effective thickness;
[0029] Figure 5 It is the curve diagram that the selection of volume Bragg grating to wavelength changes with effective thickness. DETAILED DESCRIPTION
[0030] The utility model will be further explained in connection with the drawings and examples below, but the scope of the utility model is not limited to the scope.
[0031] Referring to Figure 1 As shown, Figure 1 The light path structure of the existing holographic sighting telescope is that the laser diode emits a light beam, which is irradiated to a holographic diffraction grating in a plane wave after passing through a mirror and a collimating mirror, the holographic diffraction grating deflects the light beam to a fixed angle and irradiates it to a hologram to diffract an image, and the light beam not participating in the diffraction is blocked by a structure. The existing holographic sighting telescope uses a laser diode as an illumination light source in the light path, and the center wavelength of the light source will shift with temperature changes, which changes the position of the holographic image. As shown, Figure 2 The change of 2 nm in the wavelength of the light source irradiated to the holographic reticle changes the imaging angle by 0.086°, and when the sighting distance is 100 m, the holographic reticle image is shifted by 0.15 m. Therefore, a holographic diffraction grating is generally used in the light path structure to compensate for the influence of the wavelength change, and by this method, the change of the imaging angle can be reduced to 0.0038°, and when the sighting distance is 100 m, the holographic reticle image is shifted by 6.7*10 -3 m. However, due to the size limitation of the device structure, it is difficult to place the holographic diffraction grating parallel to the holographic reticle, which reduces the compensation effect.
[0032] Based on this, the utility model embodiment provides a holographic sighting telescope based on volume Bragg grating, as shown, Figure 3 The holographic sighting telescope comprises a sighting telescope shell 6, an illumination light system and a holographic reticle 5.
[0033] The illumination light system and the holographic reticle 5 are arranged inside the sighting telescope shell 6.
[0034] The sighting telescope shell 6 is provided with a sighting telescope window.
[0035] The illumination light system comprises a semiconductor laser 1, a wave locking element 2, a beam expander 3 and an off-axis parabolic mirror 4.
[0036] The holographic reticle 5 is provided with a hologram of a sighting reticle mark.
[0037] The wave locking element 2 is a reflective volume Bragg grating, and the holographic reticle 5 is a transmissive volume Bragg grating.
[0038] The light emitted by the semiconductor laser 1 passes through the wave-locking element 2, the wave-locking element 2 returns the parallel light part with the incident angle of 0° to the cavity of the semiconductor laser 1 to form the resonant wave-locking (wavelength locking), the parallel light transmitted through the wave-locking element 2 successively passes through the beam expanding of the beam expander 3 and the collimation of the off-axis parabolic mirror 4 to obtain the parallel light with the collimated beam diameter large enough, and the parallel light is irradiated onto the holographic graticule 5 (containing the holographic information of the graticule mark) to form the holographic image of the graticule mark; the aiming graticule mark is reproduced in the direction of the human eye observation, and the virtual image of the graticule mark is generated at the position close to the infinite distance from the human eye; when the human eye observes through the sighting window, the virtual image of the graticule mark is overlapped with the aiming target to realize the aiming function.
[0039] In the embodiment, the wave-locking element 2 and the holographic graticule 5 are two different volume Bragg gratings, the former is a reflective volume Bragg grating, and the latter is a transmissive volume Bragg grating, and the characteristics of both are that when the wavelength and the incident angle of the light satisfy the Bragg diffraction condition, the incident light will produce the corresponding diffraction phenomenon, otherwise the light will directly pass through the volume Bragg grating along the beam direction and no diffraction occurs. Figure 4 and Figure 5 The selectivity of the thickness of the volume Bragg grating to the light source angle and wavelength is respectively shown, which indicates that the volume Bragg grating can effectively control the diffraction condition of the light source.
[0040] In the embodiment, the thickness of the reflective volume Bragg grating is 1-3 mm, and the thickness of the transmissive volume Bragg grating is 0.5-3 mm, so as to realize the high wave-locking performance and diffraction efficiency.
[0041] In the embodiment, the materials of the wave-locking element 2 and the holographic graticule 5 are both photothermal volume Bragg gratings, the photothermal volume Bragg grating is less affected by the external temperature, and generally, the wavelength drift coefficient thereof is about 0.01 nm / ℃, while the wavelength drift coefficient of the semiconductor laser is about 0.3 nm / ℃. Under the same temperature variation range, when the wavelength of the semiconductor laser deviates by 2 nm, the output wavelength of the photothermal volume Bragg grating deviates only by 0.067 nm. Therefore, under the condition that the wavelength and angle of the light source are stable, the deviation of the holographic image of the graticule mark can be reduced from 0.15 m to 5*10 -3 m.
[0042] In the embodiment, the wave-locking element 2 is placed at 0° with the normal direction and the direction of the light emitted by the semiconductor laser 1, so that the parallel light part with the incident angle of 0° is reflected into the cavity of the semiconductor laser 1 to form the wavelength locking.
[0043] In the embodiment, the main optical axis of the beam expander 3 is parallel to the transmission direction and is placed in parallel, and the beam expander 3 is a double-concave lens.
[0044] In the embodiment, the outgoing light of the semiconductor laser 1 is first irradiated onto the wave-locking element 2, the normal direction of the wave-locking element 2 is parallel to the light source direction, so that the parallel light part with an incident angle of 0° is partially reflected into the cavity of the semiconductor laser 1 to form a resonant wave-locking, the parallel light transmitted through the wave-locking element 2 enters the beam expander 3, the main optical axis of the beam expander 3 is parallel to the direction of the transmitted light, the off-axis parabolic mirror 4 is placed in the outgoing direction of the beam expander 3, and the light expanded (also referred to as enlarged) by the beam expander 3 is collimated to obtain parallel light with a large enough beam diameter, and the parallel light is reflected along a direction with an angle of 40-80° (preferably 60°) with the normal direction of the holographic reticle, and finally irradiated onto the holographic reticle 5, so that the aiming reticle is reproduced in the observation direction of the human eye, and a virtual image of the reticle is generated at a distance close to infinity from the human eye. When the human eye observes through the sighting window, the virtual image of the reticle is coincided with the aiming target, so that the aiming function is realized.
[0045] Compared with the prior art, the embodiment has the following beneficial effects:
[0046] 1) In the embodiment, the transmission type volume Bragg grating is used as the holographic recording medium, and the reflection type volume Bragg grating is used as the wave-locking element, so that the wavelength of the semiconductor laser is stabilized, the influence of the wavelength drift on the holographic imaging position is suppressed, and the precision and stability of the holographic sighting telescope are increased.
[0047] 2) In the embodiment, the light-induced thermal birefringence glass with a higher refractive index modulation is used to manufacture the transmission type volume Bragg grating, so that a higher diffraction efficiency can be achieved when the thickness is constant, the displayed holographic image is brighter, and the recognition degree is higher; at the same time, the material has good mechanical stability, thermal stability, chemical stability and high transmittance, the holographic information is easy to save, and is less affected by the external temperature, so that additional coating or glue sealing protection is not needed, and the observation window is bright;
[0048] 3) In the embodiment, the beam expander and the off-axis parabolic mirror are used to collimate the light source after expansion, so that the system optical path is shortened, the size of the holographic sighting telescope is effectively reduced, and the size of the holographic sighting telescope can be: length L=85-90nm, width W=55nm, and height H=65-70nm. Compared with the existing holographic sighting telescope, the size is smaller, and the assembly space is saved.
Claims
1. A holographic riflescope based on volume Bragg grating, characterized in that, The holographic scope comprises a scope shell, an illumination light system and a holographic reticle; The illumination light system and the holographic reticle are arranged inside the scope shell; The scope shell is provided with a scope window; The illumination light system comprises a semiconductor laser, a wave-lock element, a beam expander and an off-axis parabolic reflector; The holographic reticle is provided with a holographic image of aiming reticle marks; The wave-lock element is a reflective volume Bragg grating, and the holographic reticle is a transmissive volume Bragg grating; The light emitted by the semiconductor laser passes through the wave-lock element, the wave-lock element returns the parallel light with an incident angle of 0° to the semiconductor laser cavity to form resonant wave-lock, the parallel light transmitted by the wave-lock element passes through the beam expander and the off-axis parabolic reflector in sequence to obtain collimated parallel light, and the collimated parallel light is irradiated onto the holographic reticle to form a holographic image of aiming reticle marks; the aiming reticle marks are reproduced in the direction of human eye observation, and a virtual image of the aiming reticle marks is generated at a distance close to infinity from the human eye; when the human eye observes through the scope window, the virtual image of the aiming reticle marks is overlapped with the aiming target to realize the aiming function.
2. The holographic riflescope based on volume Bragg grating according to claim 1, characterized in that, The wave-lock element is placed at 0° with respect to the direction of the light emitted by the semiconductor laser, so that the parallel light with an incident angle of 0° is returned to the semiconductor laser cavity to form resonant wave-lock.
3. The holographic riflescope based on volume Bragg grating of claim 1, wherein, The main optical axis of the beam expander is parallel to the direction of the transmitted light, and the beam expander is a double-concave lens.
4. The holographic riflescope based on volume Bragg grating of claim 1, wherein, The off-axis parabolic reflector is placed in the direction of the light emitted by the beam expander, and the angle between the irradiation direction of the collimated parallel light and the normal direction of the holographic reticle is 40-80°.
5. The holographic riflescope based on volume Bragg grating of claim 4, wherein, The off-axis parabolic reflector is placed in the direction of the light emitted by the beam expander, and the angle between the irradiation direction of the collimated parallel light and the normal direction of the holographic reticle is 60°.
6. The holographic riflescope based on volume Bragg grating of claim 1, wherein, The wave-lock element is photo-thermal refractive glass, and the holographic reticle is photo-thermal refractive glass.
7. The holographic riflescope based on volume Bragg grating of claim 1, wherein, The thickness of the reflective volume Bragg grating is 1-3 mm, and the thickness of the transmissive volume Bragg grating is 0.5-3 mm.
8. The holographic riflescope based on volume Bragg grating of claim 1, wherein, The size of the holographic scope is: length L=85-90 nm, width W=55 nm, and height H=65-70 nm.