A compact optical system
By designing a compact optical system and utilizing a hybrid catadioptric and reflective optical path and a rubber ring connection, the stability of optical components and the problem of large exit pupil imaging in space-constrained scenarios were solved, enabling stable large field-of-view imaging on small devices such as armored vehicles.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGRAO GUANGRUI TECHNOLOGY CO LTD
- Filing Date
- 2025-09-16
- Publication Date
- 2026-07-07
AI Technical Summary
In space-constrained application scenarios, how to achieve stable large exit pupil imaging, especially how to reasonably optimize the spatial layout of optical components on small devices such as armored vehicles and maintain the stability of their relative positions, while overcoming the challenges of small imaging devices.
A compact optical system was designed, including a first prism, a transmission mirror, and a lens group. By using a hybrid light path of refraction and reflection, combined with connecting structures such as rubber rings, the relative positions and distances of the optical components are optimized to form a smaller focal length and a larger exit pupil size, ensuring good imaging even when the external environment is shaking.
It achieves large field of view and large exit pupil imaging in a limited space, improves the stability and space utilization of the optical system, and ensures the stability of imaging quality under external environmental interference.
Smart Images
Figure CN224471901U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical imaging, and more specifically relates to a compact optical system. Background Technology
[0002] In the existing technology, the common application of far-viewing displays is to place them in large spaces such as desks. Since space is not a limitation, there is no need to consider the spatial layout of the imaging optical path. In addition, due to the stability of the placement space, there is no need to make special treatment to maintain the relative positions of the various optical components when designing the optical path.
[0003] However, for applications with limited space, such as telephoto imaging devices mounted on armored vehicles, optimizing space and ensuring the relative positions of optical components remain stable despite external movement are crucial. Furthermore, achieving a larger exit pupil for small telephoto imaging devices is another challenge that needs to be overcome. Utility Model Content
[0004] This invention is proposed based on the above-mentioned needs of the prior art. The technical problem to be solved by this invention is to provide a compact optical system for stable imaging with a large exit pupil.
[0005] To solve the above problems, the technical solution provided by this utility model includes:
[0006] A compact optical system is provided, comprising: a first prism having an inclined first surface, a second surface spaced a predetermined distance from the first surface, and a third surface disposed between the first and second surfaces; a second prism having a fourth surface and disposed with the first surface; a transmissive mirror disposed opposite to the second surface, wherein the transmissive mirror allows light to pass through on its side near the first prism and reflects light on its side away from the first prism; a first lens group disposed on the side of the second prism away from the first prism; and a display disposed opposite to the third surface; light emitted from the display is incident on the third surface of the first prism, reflected by a beam splitter on the first surface to the transmissive mirror, and after reflection, is incident again on the beam splitter, and exits through transmission by the beam splitter, refraction by the second lens, and refraction by the first lens group toward the exit pupil; the focal length of the compact optical system is less than 56 mm, and the exit pupil diameter is greater than 70 mm.
[0007] The above settings allow for a reasonable optimization of the spatial layout. Furthermore, due to the small focal length of the optical system, the image formed at the exit pupil has a large exit pupil size. Additionally, the closer proximity of the various optical components allows them to abut against each other or against the rubber rings placed between them, making the entire system more stable. Even when the external environment is shaking, the entire optical system can still maintain good imaging. Moreover, the reasonable spatial layout and small focal length enable the entire optical system to be miniaturized.
[0008] Preferably, the compact optical system further includes a second lens group disposed between the display and the third surface, wherein the light emitted by the display passes through the second lens group and is then emitted toward the first prism.
[0009] By setting up a second lens group, the field curvature of the system can be corrected, thereby ensuring normal imaging in the end.
[0010] Preferably, the origin O is taken as the midpoint of the exit pupil, the Z-axis is the direction toward the compact optical system, the Y-axis is the direction perpendicular to the Z-axis and pointing upwards, and the X-axis is the direction perpendicular to the ZOY plane; the distance from the center of the surface of the first lens group near the exit pupil to the XOY plane is not less than 30 mm; the distance from the center of the surface of the first lens group away from the exit pupil to the XOY plane is not greater than 55 mm; the farthest distance from the center of the surface of the second prism near the exit pupil to the XOY plane is less than 60 mm; the farthest distance from the center of the surface of the transflector to the XOY plane is less than 140 mm; and the farthest distance from the center of the surface of the display screen near the third surface to the XOZ plane is less than 65 mm.
[0011] Preferably, the surface of the transflector mirror closest to the second surface is in contact with the second surface.
[0012] The above settings make the system more compact and stable, and reduce the interference of the external environment on imaging.
[0013] Preferably, the surface of the first lens group away from the exit pupil is in at least partial contact with the surface of the second prism near the exit pupil, or both are respectively abutting against a spacer disposed between them.
[0014] The above settings make the system more compact and stable, and reduce the interference of the external environment on imaging.
[0015] Preferably, the surface of the transflector away from the exit pupil has an arc shape, is concave in the direction away from the exit pupil, and the surface of the transflector away from the exit pupil is coated with a total reflection film.
[0016] Preferably, the exit pupil diameter of the compact optical system is not less than 70 mm.
[0017] Preferably, the diagonal field of view of the compact optical system is not less than 48°.
[0018] Compared with existing technologies, the compact optical system disclosed in this utility model reduces the distance between various optical components by decreasing the focal length of the optical system, thereby miniaturizing the overall size of the optical system. Furthermore, the close proximity of the various optical components allows for mutual contact or contact with rubber rings positioned between them, making the entire system more stable and ensuring good imaging even when subjected to external vibrations. It also results in a larger exit pupil size for the final image formed at the exit pupil. In addition, it allows for optimized spatial layout, enabling the formation of a good wide field of view image even in limited space. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings.
[0020] Figure 1 This is a schematic diagram of the structure of a compact optical system according to an embodiment of the present invention;
[0021] Figure 2 This is a schematic diagram of the coordinate system of the compact optical system in an embodiment of this utility model;
[0022] Figure 3 This is a schematic diagram of the imaging structure of one feasible implementation of the present utility model;
[0023] Figure 4 This is a schematic diagram of imaging distortion data for one feasible implementation of this utility model.
[0024] Figure 5 This is a schematic diagram of the imaging structure of another feasible embodiment of the present utility model;
[0025] Figure 6 This is a schematic diagram of imaging distortion data for another feasible implementation of this utility model.
[0026] Figure label:
[0027] 1. Display; 2. First prism; 2A. First surface; 2B. Second surface; 2C. Third surface; 3. Second prism; 3A. Fourth surface; 4. First lens group; 5. Second lens group; 6. Transmitting and reflecting mirror; 7. Beam splitter; 8. Exit pupil. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0029] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the term "connected" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0030] Throughout the text, the terms “top,” “bottom,” “above,” “below,” and “on top” refer to the relative positions of components of the device, such as the relative positions of the top and bottom substrates within the device. It is understood that the device is multifunctional and independent of its spatial orientation.
[0031] To facilitate understanding of the embodiments of this application, the following will provide further explanation and description with reference to the accompanying drawings and specific embodiments. These embodiments do not constitute a limitation on the embodiments of this application.
[0032] This embodiment provides a compact optical system, such as Figures 1-6 As shown.
[0033] like Figure 1 As shown, the compact optical system includes a display 1, a first prism 2, a transflector 6, and a first lens group 4.
[0034] Display 1 emits light to provide light propagating in the compact optical system.
[0035] A first prism 2 is disposed opposite to the display 1. The first prism 2 has a first surface 2A that is tilted, a second surface 2B that is spaced apart from the first surface 2A by a predetermined distance, and a third surface 2C disposed between the first surface 2A and the second surface 2B. The third surface 2C is at least partially opposite to the first surface 2A. Furthermore, the first prism 2 has a shape similar to a triangular prism. The third surface 2C is disposed opposite to the display 1 such that light emitted from the display 1 passes through the third surface 2C and then enters the first surface 2A.
[0036] The second prism 3 has a fourth surface 3A, which is adapted to the first surface 2A, i.e., the two fit together.
[0037] A beam-splitting film is disposed between the fourth surface 3A and the first surface 2A.
[0038] The beam splitter 7 is an optical element that can split incident light into two optical paths for output. Specifically, a portion of the light incident on the beam splitter 7 is output in the form of transmission, and the other portion is output in the form of reflection. Transmission and reflection are respectively transmitted from two sides of the beam splitter 7.
[0039] Light emitted from display 1 enters first prism 2 through third surface 2C and is incident on beam-splitting film 7. Based on the physical properties of beam-splitting film 7, the light is split into two paths: one path reflected off beam-splitting film 7 and the other path transmitted through reflective film 7. The reflected light is the effective light and continues to propagate within the compact optical system. The transmitted light exits outside the compact optical system, no longer affecting the propagation of the effective light and not interfering with its subsequent propagation.
[0040] Furthermore, the plane containing the first surface 2A forms a 45° angle with the plane containing the display 1. The light reflected by the beam splitter 7 propagates in the first prism 2, and the light transmitted through the beam splitter 7 propagates in the second prism 3.
[0041] The transmissive mirror 6 is positioned opposite to the second surface 2B. Specifically, light rays emitted from the first prism 2 can enter the transmissive mirror 6. Furthermore, the side of the transmissive mirror 6 closest to the exit pupil 8 contacts the second surface 2B.
[0042] The transflecting mirror 6 has a side that transmits light and a side that reflects light. The side closer to the exit pupil 8 transmits light, while the side farther from the exit pupil 8 is coated with a total reflection film to reflect light. The light transmitted by the first prism 2 passes through the side closer to the exit pupil 8 in a transmitted form, enters the total reflection film, and after being reflected by the total reflection film, exits again through the side of the transflecting mirror 6 closer to the exit pupil 8 and enters the first prism 2.
[0043] The light rays that re-enter the first prism 2 will be incident on the beam splitter. At this time, part of the incident light rays will be reflected and output from the first prism 2 to the outside of the compact optical system, while the other part will be transmitted from the second prism 3 toward the exit pupil 8. The transmitted light rays are the effective light rays.
[0044] A first lens group 4 is disposed opposite to the second prism 3. The first lens group 4 and the transmission and reflection mirror 6 are respectively disposed on both sides of the second prism 3 and the first prism 2. The surface of the first lens group 4 away from the exit pupil 8 is in at least partial contact with the surface of the second prism 3 near the exit pupil 8, or both are respectively abutted against a spacer disposed between them.
[0045] The light rays entering the first lens group 4 are refracted and then emitted towards the exit pupil 8, forming the first image.
[0046] Furthermore, the compact optical system also includes a second lens group 5, disposed between the display 1 and the third surface 2C. Light emitted from the display 1 passes through the second lens group 5 and then enters the first prism 2. This corrects the field curvature of the compact optical system, thereby ensuring accurate imaging.
[0047] To facilitate the description of the relative positions of the optical components in a compact optical system and the space occupied by the entire optical system, a system is established as follows: Figure 2 The coordinate system shown.
[0048] With the midpoint of the exit pupil 8 as the origin O, the direction horizontal towards the compact optical system as the Z-axis, the direction vertically upward as the Y-axis, and the direction perpendicular to the ZOY plane as the X-axis.
[0049] The distance from the center of the surface of the first lens group 4 on the side closest to the exit pupil 8 to the XOY plane is not less than 30mm, and the distance from the center of the surface of the first lens group 4 on the side furthest from the exit pupil 8 to the XOY plane is not greater than 55mm.
[0050] The furthest distance from the center of the surface of the second prism 3 closest to the exit pupil 8 to the XOY plane is less than 60 mm.
[0051] The farthest distance from the center of the surface of the mirror 6 away from the exit pupil 8 to the XOY plane is less than 140 mm.
[0052] The furthest distance from the center of the third surface 2C of the display screen to the XOZ plane is less than 65mm.
[0053] Based on the above-mentioned relative positions, the exit pupil diameter W of the compact optical system is not less than 70 mm, and the diagonal field of view is not less than 48°.
[0054] like Figure 3 As shown, a feasible implementation of this embodiment will be given below. The compact optical system formed by this implementation has a system field of view of 48.4°, an exit pupil diameter of 72mm, a system focal length of 55mm, and a final image focal depth of -3000mm. The optical system parameters in this embodiment are shown in Table 1. The optical surface numbers in Table 1 correspond to... Figure 3The various surfaces in the system. Table 2 shows the aspherical coefficients in the compact optical system.
[0055] Table 1 Optical System Parameters
[0056] Of the surfaces mentioned above, the surfaces that make up the sphere satisfy the following equation: c is the reciprocal of the radius of curvature, and r is the radial distance from a point on the surface. The surface constituting an aspherical surface satisfies the equation: c is the reciprocal of the radius of curvature, r is the radial distance from a point on the surface, k is the quadratic surface constant, and A i These are the coefficients of higher-order terms.
[0057] Table 2 Aspherical Coefficients
[0058] 107a 107b R(1 / c) 6.513931E+01 -1.077202E+03 k 1.349862E+00 1.000000E+01 <![CDATA[A2]]> -2.831913E-06 4.930888E-06 <![CDATA[A3]]> 4.347218E-09 -3.189915E-08 <![CDATA[A4]]> -2.779500E-11 3.096146E-11 <![CDATA[A5]]> 1.321620E-14 -9.569949E-15 <![CDATA[A6]]> 6.079207E-18 2.565979E-18
[0059] The imaging distortion curve of the compact optical system formed by the above embodiments is as follows: Figure 4 As shown, the horizontal axis represents the distortion value, and the vertical axis represents the field of view (expressed as image height); the system distortion is less than 2%.
[0060] like Figure 5 As shown, another feasible implementation of this embodiment is given below. This implementation forms a compact optical system with a system field of view of 48.3°, an exit pupil diameter of 72mm, a system focal length of 55mm, and a final image focal depth of -3000mm. The optical system parameters in this implementation are shown in Table 3. The optical surface numbers in Table 3 correspond to... Figure 5 The various surfaces in the system. Table 4 shows the aspherical coefficients in a compact optical system.
[0061] Table 3 Optical System Parameters
[0062]
[0063]
[0064] Table 4 Aspherical Coefficients
[0065] 207a 207b R(1 / c) 7.7339821E+01 -1.5997001E+03 k 2.0357871E+00 -1.0000000E+01 <![CDATA[A2]]> -2.8333001E-06 4.5337038E-07 <![CDATA[A3]]> 2.9011887E-09 -1.8688321E-08 <![CDATA[A4]]> -1.6841944E-11 2.5644069E-11 <![CDATA[A5]]> 1.1772065E-14 -1.6303073E-14 <![CDATA[A6]]> -6.0259181E-20 6.7875709E-18
[0066] The imaging distortion curve of the compact optical system formed by the above embodiments is as follows: Figure 6 As shown, the horizontal axis represents the distortion value, and the vertical axis represents the field of view (expressed as image height); the system distortion is less than 2%.
[0067] This compact optical system features a small focal length, allowing for closer proximity between optical elements and resulting in a smaller overall size. This enables the formation of a large field of view and a large exit pupil within a limited space, enhancing the viewing experience. The use of a hybrid catadioptric optical path structure further contributes to the compact system's stability. The small focal length allows for close contact between optical elements, maintaining overall stability even in unstable environments. The relative positions of the optical elements are maintained through connecting structures, such as rubber rings, ensuring image quality. The overall arrangement of optical components optimizes space utilization. Furthermore, this optical system can form distant images within a limited space (e.g., a focal depth of 3m in the described embodiment) and achieve a large exit pupil within a small footprint.
[0068] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A compact optical system, characterized in that, include: A first prism has a first surface that is inclined, a second surface that is spaced apart from the first surface by a predetermined distance, and a third surface that is disposed between the first surface and the second surface. The second prism has a fourth surface, which is matched with the first surface; A transflecting mirror is disposed opposite to the second surface. The side of the transflecting mirror that is close to the first prism allows light to pass through, while the side that is away from the first prism reflects light. The first lens group is disposed on the side of the second prism away from the first prism; The display is positioned relative to the third surface; The light emitted by the display is incident on the third surface of the first prism, reflected by the beam splitter on the first surface to the transflector, and after reflection, it is incident on the beam splitter again. It is then emitted towards the exit pupil through the transmission of the beam splitter, the refraction of the second lens, and the refraction of the first lens group. The focal length of the compact optical system is less than 56mm, and the exit pupil diameter is greater than 70mm.
2. The compact optical system according to claim 1, characterized in that, The compact optical system also includes a second lens group disposed between the display and the third surface, wherein the light emitted from the display passes through the second lens group and is then directed toward the first prism.
3. The compact optical system according to claim 1, characterized in that, With the midpoint of the exit pupil as the origin O, the direction toward the compact optical system as the Z-axis, the direction perpendicular to the Z-axis and upward as the Y-axis, and the direction perpendicular to the ZOY plane as the X-axis; The distance from the center of the surface of the first lens group near the exit pupil to the XOY plane is not less than 30mm; The distance from the center of the surface of the first lens group on the side furthest from the exit pupil to the XOY plane is no more than 55mm; The farthest distance from the center of the surface of the second prism on the side closest to the exit pupil to the XOY plane is less than 60mm; The farthest distance from the center of the surface of the mirror on the side furthest from the exit pupil to the XOY plane is less than 140 mm; The furthest distance from the center of the display surface closest to the third surface to the XOZ plane is less than 65mm.
4. The compact optical system according to claim 1, characterized in that, The surface of the transflector mirror closest to the second surface is in contact with the second surface.
5. The compact optical system according to claim 1, characterized in that, The surface of the first lens group away from the exit pupil is in at least partial contact with the surface of the second prism near the exit pupil, or both of them abut against a spacer disposed between them.
6. The compact optical system according to claim 1, characterized in that, The surface of the transflector away from the exit pupil is curved and concave in the direction away from the exit pupil, and the surface of the transflector away from the exit pupil is coated with a total reflection film.
7. The compact optical system according to claim 1, characterized in that, The exit pupil diameter of the compact optical system is not less than 70 mm.
8. The compact optical system according to claim 1, characterized in that, The diagonal field of view of the compact optical system is not less than 48°.