Optical imaging system
By designing an optical imaging system that uses prisms to achieve optical path rewinding and mixing, the problem that large outgoing pupil diameters in the prior art are difficult to achieve in limited space scenarios, and the large outgoing pupil diameters and smaller space occupation are achieved, thereby improving the imaging effect.
Patent Information
- Application Number
- CN202422257746.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2034-09-14
AI Technical Summary
While the existing optical systems pursue large pupil diameters, it is difficult to effectively reduce the space occupied by the system in application scenarios with limited space.
By designing an optical imaging system, the system includes two prisms, which control the reflection and transmission of light rays by using the incident angle of the prism to achieve rewind mixing of the optical path, avoiding the use of additional large space-occupation optics.
While ensuring a large pupil diameter, it effectively reduces the space occupation of the optical imaging system, maintains high luminous flux, improves the imaging effect, and corrects off-axis aberration through free-surface prisms.
Smart Images
Figure CN223038247U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of optical imaging, and particularly relates to an optical imaging system. Background Art
[0002] In the prior art, for an optical system, the larger the exit pupil diameter is, the better the viewer's experience is. However, the larger the exit pupil diameter is, the higher the design difficulty is. This is because when the exit pupil diameter is larger, the aperture of the lens is larger and the number of lenses is more. Considering the design difficulty of the lens arrangement, when the number of lenses is more, the occupied space of the formed optical system is larger. For an application scenario with limited space but wanting to achieve a large exit pupil, the difficulty coefficient is relatively large. Summary of the Utility Model
[0003] The present utility model is precisely proposed based on the above requirements of the prior art. The technical problem to be solved by the present utility model is to provide an optical imaging system that can occupy less space when the exit pupil diameter of the system is relatively large.
[0004] To solve the above problems, the technical solution provided by the present utility model includes:
[0005] An optical imaging system is provided, including: a light source that emits light; a first prism, including a first surface, a first optically effective surface, and a second surface, the first surface is disposed opposite to the light source, the first optically effective surface is opposite to the first surface, the second surface is disposed opposite to the first optically effective surface, light enters the first prism through the first surface and exits towards the first optically effective surface, the incident angle on the first optically effective surface is greater than the total internal reflection angle of the first prism so that the light is reflected on the first optically effective surface, and the reflected light transmits through the second surface and exits from the first prism; a second prism, including a second optically effective surface, a first surface, and a second surface, the second optically effective surface is disposed opposite to the first prism, and the second optically effective surface is respectively opposite to the first surface and the second surface, and a reflective film is plated on the first surface; the light exiting from the first prism enters the second prism through the second optically effective surface and exits towards the first surface, after being reflected by the reflective film, it is incident on the second optically effective surface, and its incident angle is greater than the total internal reflection angle of the second prism, so that the light is reflected on the second optically effective surface, and the reflected light passes through the second surface and exits towards the exit pupil position to form a first image.
[0006] Through the above settings, it is possible to ensure that the optical imaging system has a relatively large exit pupil diameter while minimizing the space occupied by the optical imaging system. Only using a prism can simultaneously achieve the light path changes of transmission and reflection. Specifically, by setting the angle of incidence on the prism, a folded-back hybrid optical path structure can be realized, enabling reflection to be completed by the prism without the need for other large-space-occupying optical devices. In addition, a beam splitter is usually used to simultaneously achieve transmission and reflection, which not only requires additional space occupation but also sacrifices a part of the light flux, that is, loses a part of the light rays. By using a prism, appropriate refraction and reflection can be carried out while ensuring the light flux, guaranteeing the integrity of the optical path.
[0007] Preferably, taking the center of the exit pupil of the optical imaging system as the origin O, the direction of the exit pupil horizontally towards the second prism as the Z-axis, the vertically upward direction as the Y-axis, and one of the directions perpendicular to the YOZ plane as the X-axis, a local coordinate system is formed. The distance range from the origin to the second surface of the second prism is 10 mm to 20 mm, the Y eccentricity range of the second surface is -3 mm to 3 mm, and the tilt angle range with the XOY plane is -15° to 15°; the Z eccentricity range of the center of the second optical effective surface of the second prism is 20 mm to 30 mm, the Y eccentricity range is -3 mm to 3 mm, and the tilt angle range with the XOY plane is 40° to 60°; the Z eccentricity range of the center of the first surface of the second prism is 20 mm to 30 mm, the Y eccentricity range is 5 mm to 15 mm, and the tilt angle range with the XOY plane is 75° to 95°.
[0008] Preferably, the Z eccentricity range of the center of the second surface of the first prism is 21 mm to 31 mm, the Y eccentricity range is -3 mm to 3 mm, and the tilt angle range with the XOY plane is 32° to 52°; the Z eccentricity range of the center of the first optical effective surface of the first prism is 25 mm to 35 mm, the Y eccentricity range is -10 mm to 0 mm, and the tilt angle range with the XOY plane is 5° to 25°; the Z eccentricity range of the center of the first surface of the first prism is 20 mm to 30 mm, the Y eccentricity range is -13 mm to -3 mm, and the tilt angle range with the XOY plane is 24° - 44°.
[0009] Preferably, the Z eccentricity range of the center of the light source surface is 18 mm - 28 mm; the Y eccentricity range is -14 mm to -4 mm, and the tilt angle range with the XOY plane is 35° - 55°.
[0010] Preferably, the focal length range of the first prism is 100 mm to 200 mm.
[0011] Preferably, the focal length range of the second prism is 12 mm to 21 mm.
[0012] Preferably, the focal length range of the optical imaging system is 11 mm to 20 mm.
[0013] Preferably, the diagonal field of view formed by the optical imaging system is not less than 40°, the field of view angle in the horizontal direction is greater than or equal to 33°, and the exit pupil diameter is greater than 8 mm.
[0014] Preferably, the first prism and the second prism are free-form surface prisms.
[0015] Through the above settings, the off-axis aberration of the optical imaging system is corrected.
[0016] Preferably, the focal plane depth range of the first image is -1000 mm to -∞, and +200 mm to +∞.
[0017] Compared with the prior art, in the present utility model, due to the relative positional relationship of each optical device, only by setting the prisms can the requirements of both transmission and reflection be achieved simultaneously, without adding other optical devices. At the same time, a relatively high light flux can be maintained to improve the imaging effect. In addition, the optical imaging system involved in the present application can form a relatively large exit pupil size, thus bringing a good visual experience to the viewer. At the same time, it occupies a relatively small space and can be flexibly adapted to various scenarios. Further, the first prism and the second prism are free-form surface prisms, which can well correct the off-axis aberration of the optical system, thereby enhancing the viewing experience. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present specification. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.
[0019] Figure 1 It is a schematic structural diagram of an optical imaging system in an embodiment of the present utility model;
[0020] Figure 2 It is a schematic diagram of a local coordinate system of the optical imaging system in an embodiment of the present utility model;
[0021] Figure 3 It is a schematic diagram of an optical imaging system formed by a feasible implementation manner in an embodiment of the present utility model;
[0022] Figure 4 It is a schematic diagram of a sampling field of view MTF curve under a feasible implementation manner in an embodiment of the present utility model;
[0023] Figure 5 It is a schematic diagram of a distortion grid under a feasible implementation manner in an embodiment of the present utility model.
[0024] Reference numerals:
[0025] 1. Light source; 2. First prism; 3. Second prism; 4. First face; 5. First optically effective face; 6. Second face; 7. First surface; 8. Second optically effective face; 9. Second surface; 10. Exit pupil. Detailed implementation manners
[0026] To make the objectives, technical solutions and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of rather than all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.
[0027] In the description of the embodiments of this utility model, it should be noted that unless otherwise clearly defined and limited, the term "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.
[0028] The terms "top", "bottom", "above", "below" and "on" used throughout the description are relative positions with respect to the components of the device, such as the relative positions of the top and bottom substrates inside the device. It can be understood that the device is multifunctional and is independent of its orientation in space.
[0029] To facilitate the understanding of the embodiments of this application, the following will further explain with specific examples with reference to the accompanying drawings. The examples do not constitute a limitation to the embodiments of this application.
[0030] This embodiment provides an optical imaging system, as Figure 1 shown.
[0031] The optical imaging system includes a light source 1, a first prism 2, and a second prism 3.
[0032] The light source 1 emits light to provide a light source for the optical imaging system.
[0033] The light source 1 can be a display, can be a lamp bead, or can be a lamp bead matrix formed by arranging lamp beads to display a specific pattern. The light source 1 can be adapted according to requirements.
[0034] The first prism 2 is disposed opposite to the light source 1. The first prism 2 includes a first optically effective surface 5, a first surface 4, and a second surface 6.
[0035] The first surface 4 is the optical surface of the first prism 2 that first receives light. It is disposed opposite to the light source 1. The light emitted by the light source 1 enters the first prism 2 through the first surface 4, and the light passes through the first surface 4 in a transmissive form.
[0036] The first optically effective surface 5 is disposed opposite to the first surface 4. The light passing through the first surface 4 will be incident on the first optically effective surface 5, and the incident angle is greater than the total internal reflection angle of the first prism 2, so that the light is reflected on the first optically effective surface 5. Specifically, the incident angle of the light emitted by the light source 1 on the first optically effective surface 5 is greater than arcsin(1 / n), where n is the refractive index of the material of the first prism 2.
[0037] By setting the incident angle of the light, the reflection of the light can be realized without relying on optical devices for reflection such as a reflective film, so as to save the space and cost of the optical system, make the optical system more compact, and occupy less space.
[0038] The second surface 6 is the optical surface of the first prism 2 that finally passes the light. It is disposed opposite to the first optically effective surface 5. After being reflected by the first optically effective surface 5, the light is emitted towards the second surface 6, and the light incident on the second surface 6 will pass through the second surface 6 in a transmissive form and exit from the first prism 2.
[0039] The second prism 3 is disposed opposite to the first prism 2. The second prism 3 includes a second optically effective surface 8, a first surface 7, and a second surface 9.
[0040] The second optically effective surface 8 is disposed opposite to the second surface 6. It is the optical surface of the second prism 3 that first receives light. The light passing through the second surface 6 will be incident on the second optically effective surface 8 and enter the second prism 3 through the second optically effective surface 8.
[0041] The first surface 7 is disposed opposite to the second optically effective surface 8. A reflective film is deposited on the first surface 7. The light of the light source 1 passing through the second optically effective surface 8 is incident on the first surface 7. After being reflected by the reflective film, it is incident on the second optically effective surface 8 again. At this time, the incident angle is greater than the total internal reflection angle of the second prism 3, so that the light will be output in a reflective form. Specifically, after being reflected by the reflective film on the first surface 7, the angle incident on the second optically effective surface 8 is greater than arcsin(1 / n'), where n' is the refractive index of the material of the second prism 3.
[0042] The second surface 9, which is the last optical surface that the light passes through in the second prism 3, is disposed opposite to the second optically effective surface 8. After being reflected by the second optically effective surface 8, the light exits from the second surface 9 in a transmissive form and forms a first image at the position of the exit pupil 10.
[0043] Furthermore, the first prism and the second prism are free-form prisms, which can correct the off-axis aberration of the system. In addition, the two free-form prisms can be made of moldable low-melting glass or injection-moldable optical resin materials.
[0044] In summary, the optical path formed in the optical imaging system is as follows: The light emitted from the light source 1 is incident on the first prism 2. After passing through the first surface 4 by transmission, it is incident on the first optically effective surface 5. After being reflected by the first optically effective surface 5, it passes through the second surface 6 and exits the first prism 2, enters the second prism 3, passes through the second optically effective surface 8 by transmission and is incident on the first surface 7. Through the reflection of the deposited reflective film, it is incident on the second optically effective surface 8 again. After being reflected, it is output through the second surface 9, exits towards the exit pupil 10 and forms a first image. When the light is transmitted in the two free-form prisms, a total of three reflections occur, but two of them work in the way of total internal reflection, without the need for coating, saving manufacturing and process complexity.
[0045] To clarify the relative positional relationship of each optical device and the involved optical surfaces in the optical imaging system, a local coordinate system of the optical imaging system is established. Specifically: as Figure 2 shown, taking the center of the exit pupil 10 as the origin O of the local coordinate system, the direction of the exit pupil 10 horizontally towards the second prism 3 as the Z-axis, the vertically upward direction as the Y-axis, and one of the directions perpendicular to the YOZ plane as the X-axis to form a local coordinate system.
[0046] Observed from the position of the system exit pupil 10, the diagonal field of view of the optical imaging system is not less than 40°, the field of view angle in the horizontal direction is greater than 33°, and the diameter of the exit pupil 10 is greater than 8 mm.
[0047] The Z eccentricity range of the center of the first surface 4 of the first prism 2 is 20 mm to 30 mm, the Y eccentricity range is -13 mm to -3 mm, and the tilt angle range with the XOY plane is 24° - 44°.
[0048] The Z eccentricity range of the center of the first optically effective surface 5 of the first prism 2 is 25 mm to 35 mm, the Y eccentricity range is -10 mm to 0 mm, and the tilt angle range with the XOY plane is 5° to 25°.
[0049] The Z eccentricity range of the center of the second surface 6 of the first prism 2 is 21 mm to 31 mm, the Y eccentricity range is -3 mm to 3 mm, and the tilt angle range with the XOY plane is 32° to 52°.
[0050] The Z eccentricity range at the center of the second optical effective surface 8 of the second prism 3 is 20 mm to 30 mm, the Y eccentricity range is -3 mm to 3 mm, and the tilt angle range with respect to the XOY plane is 40° to 60°.
[0051] The Z eccentricity range at the center of the first surface 7 of the second prism 3 is 20 mm to 30 mm, the Y eccentricity range is 5 mm to 15 mm, and the tilt angle range with respect to the XOY plane is 75° to 95°.
[0052] The distance range from the origin to the second surface 9 of the second prism 3 is 10 mm to 20 mm, the Y eccentricity range of the second surface 9 is -3 mm to 3 mm, and the tilt angle range with respect to the XOY plane is -15° to 15°.
[0053] The Z eccentricity range at the center of the surface of the light source 1 is 18 mm - 28 mm; the Y eccentricity range is -14 mm to -4 mm, and the tilt angle range with respect to the XOY plane is 35° - 55°.
[0054] In the above optical imaging system, the focal length range of the first prism 2 is 100 mm to 200 mm, the focal length range of the second prism 3 is 12 mm to 21 mm, the focal length range of the optical imaging system is 11 mm to 20 mm, and the focal plane depth range of the formed first image is -1000 mm to -∞, and +200 to +∞.
[0055] For the convenience of understanding the overall technical solution, a specific and feasible implementation manner will be given here. The optical imaging system is as Figure 3 shown. The field of view angle of the final image is 40°, the diameter of the exit pupil 10 is 8 mm, the focal plane depth is -3000 mm, the system focal length is 15.4 mm, and the optical coefficients of the optical surfaces forming the optical imaging system are shown in Table 1.
[0056] Table 1 Optical System Parameters
[0057]
[0058]
[0059] Among the above surfaces, the surfaces constituting the freeform surface satisfy the equation: c is the reciprocal of the radius of curvature, r is the radial distance of a point on the surface, k is the conic constant, and C i is the high-order term coefficient.
[0060] Among them, 100 is the first image, 101 is the exit pupil, 102 is the second surface, 103 is the second optically effective surface, 104 is the first surface, 105 is the second face, 106 is the first optically effective surface, 107 is the first face, 108 is the cover plate surface in front of the light-emitting surface of the light source, and 109 is the light-emitting surface of the light source.
[0061] Based on Table 1, the free-form coefficients of the optical surfaces with the surface type of free-form surface are shown in Table 2.
[0062] Table 2 Free-form Coefficients
[0063]
[0064]
[0065] In the above specific embodiments, the sampling field MTF curve that can form the first image, that is, the Modulation Transfer Function, is as Figure 4 shown. The MTF curve is a term in optical engineering and is often used to evaluate the performance of an optical system. The abscissa represents the sampling frequency in the image space, the ordinate represents the contrast, F1 to F9 are the sampling fields used to evaluate the display quality of the system, and X and Y represent two directions respectively. The MTF values of each field at 30 lp / mm are higher than 0.5, indicating that the above system has excellent imaging. As Figure 5 shown, it is the comparison of the distortion grid of the focal plane where the first image is located with the ideal focal plane. The optical distortion of the above wearable optical system is less than 8%. That is, the optical system formed by the above embodiments has relatively stable performance and can ensure the imaging quality.
[0066] The above specific embodiments have further detailed the purpose, technical solution and beneficial effects of the present application. It should be understood that the above are only the specific embodiments of the present application and are not used to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. An optical imaging system, characterized in that: include: Light source, emitting light; A first prism comprises a first surface, a first optically effective surface, and a second surface, wherein the first surface is arranged opposite to the light source, the first optically effective surface is arranged opposite to the first surface, and the second surface is arranged opposite to the first optically effective surface, light enters the first prism through the first surface and is emitted toward the first optically effective surface, and the incident angle on the first optically effective surface is greater than the total internal reflection angle of the first prism so that the light is reflected on the first optically effective surface, and the reflected light is transmitted through the second surface and emitted from the first prism; The second prism comprises a second optically effective surface, a first surface and a second surface. The second optically effective surface is arranged opposite to the first prism, and the second optically effective surface is respectively opposite to the first surface and the second surface. A reflective film is plated on the first surface. The light transmitted from the first prism passes through the second optically effective surface and enters the second prism, and is emitted toward the first surface. After being reflected by the reflective film, the light is incident on the second optically effective surface, and its incident angle is greater than the total internal reflection angle of the second prism, so that the light is reflected on the second optically effective surface, and the reflected light passes through the second surface and is emitted toward the exit pupil position to form a first image.
2. The optical imaging system according to claim 1, characterized in that: The exit pupil center of the optical imaging system is taken as the origin O, the direction of the exit pupil toward the second prism is taken as the Z axis, the vertical upward direction is taken as the Y axis, and one of the directions perpendicular to the YOZ plane is taken as the X axis to form a local coordinate system. The distance from the origin to the second surface of the second prism ranges from 10 mm to 20 mm, the Y eccentricity range of the center of the second surface ranges from -3 mm to 3 mm, and the inclination angle range with the XOY plane ranges from -15° to 15°; The center of the second optically effective surface of the second prism has a Z eccentricity range of 20 mm to 30 mm, a Y eccentricity range of -3 mm to 3 mm, and an inclination angle range of 40° to 60° with respect to the XOY plane; The center of the first surface of the second prism has a Z eccentricity range of 20 mm to 30 mm, a Y eccentricity range of 5 mm to 15 mm, and an inclination angle range with respect to the XOY plane of 75° to 95°.
3. The optical imaging system according to claim 2, characterized in that: The center of the second surface of the first prism has a Z eccentricity range of 21 mm to 31 mm, a Y eccentricity range of -3 mm to 3 mm, and an inclination angle range of 32° to 52° with respect to the XOY plane; The center of the first optically effective surface of the first prism has a Z eccentricity range of 25 mm to 35 mm, a Y eccentricity range of -10 mm to 0 mm, and an inclination angle range of 5° to 25° with respect to the XOY plane; The Z eccentricity range of the center of the first surface of the first prism is 20 mm to 30 mm, the Y eccentricity range is -13 mm to -3 mm, and the inclination angle range with respect to the XOY plane is 24° to 44°.
4. The optical imaging system according to claim 3, characterized in that: The Z eccentricity range of the center of the light source surface is 18mm-28mm; the Y eccentricity range is -14mm to -4mm, and the inclination angle range between the XOY plane and the XOY plane is 35°-55°.
5. The optical imaging system according to any one of claims 1 to 4, characterized in that: The focal length of the first prism ranges from 100 mm to 200 mm.
6. The optical imaging system according to any one of claims 1 to 4, characterized in that: The focal length of the second prism ranges from 12 mm to 21 mm.
7. The optical imaging system according to any one of claims 1 to 4, characterized in that: The focal length range of the optical imaging system is 11 mm to 20 mm.
8. The optical imaging system according to any one of claims 1 to 4, characterized in that: The diagonal field of view formed by the optical imaging system is not less than 40°, the horizontal field of view angle is greater than or equal to 33°, and the exit pupil diameter is greater than 8 mm.
9. The optical imaging system according to claim 1, characterized in that: The first prism and the second prism are free-form surface prisms.
10. The optical imaging system according to any one of claims 1 to 4, characterized in that: The focal depth of the first image ranges from -1000 mm to -∞ and from +200 mm to +∞.