Optical system

Abstract

The invention belongs to the field of optical imaging, and particularly relates to an optical system, which comprises a light source for emitting light; the first prism is arranged opposite to the light source, and light emitted by the light source penetrates through the first optical surface to enter the first prism; the light enters the second optical surface and is reflected on the total reflection film; the light enters the third optical surface and is reflected on the total reflection film; the light passes through the fourth optical surface and is emitted out of the first prism; the first optical surface, the second optical surface, the third optical surface and the fourth optical surface are curved surfaces which protrude outwards away from the center of the first prism; the light passes through the first prism and then enters the second prism; light penetrates through the first optical surface and enters the second optical surface, the incident angle of the light is larger than arctan (1 / n), and the light is reflected on the second optical surface; and after being reflected by the beam splitting film or the reflecting film, the light enters the second optical surface again, passes through the second optical surface and is emitted to the exit pupil, so that a final image with the focal plane depth greater than 0.1 m is formed.

Description

Technical Field

[0001] The invention belongs to the field of optical imaging, and in particular relates to an optical system. Background Art

[0002] In recent years, with the rapid development of wearable display technologies such as augmented reality (AR) and virtual reality (VR), the demand for lightweight, thin, and wide-field-of-view visual optical systems has become increasingly urgent. Freeform optical elements have become one of the key technologies for realizing compact optical systems due to their asymmetry and high degree of freedom in design. In the prior art, visual optical systems based on freeform prisms often compress the volume by folding the optical path, but are limited by the constraints of traditional curved surface design and have a long focal length, making it difficult to achieve a large field of view (e.g., a horizontal field of view ≥ 30°) on a small display screen. In addition, the long focal length design will also increase the axial size of the optical system, which conflicts with the requirements of wearable devices for lightweight and miniaturization.

[0003] To solve the above problems, some solutions try to improve performance by increasing the number of optical elements or complex curved surfaces. However, such designs not only significantly increase the difficulty of processing and assembly, but may also lead to reduced system light efficiency and increased costs. For example, although the solution of using a combination of multiple spherical or aspherical lenses can shorten the focal length, it is difficult to take into account aberration correction and volume control; and the traditional single free-form prism system can simplify the structure, but the insufficient length of the optical path limits the further improvement of the field of view.

[0004] Therefore, there is an urgent need for an optical system solution that can balance short focal length, large field of view, miniaturization and manufacturing feasibility to meet the needs of wearable devices for high-performance visual optical systems. Summary of the invention

[0005] The present invention is proposed based on the above-mentioned requirements of the prior art, and the technical problem to be solved by the present invention is to provide an optical system to improve performance.

[0006] In order to solve the above problems, the technical solution provided by the present invention includes:

[0007] An optical system is provided, comprising: a light source, emitting light; a first prism, arranged opposite to the light source, the first prism comprising: a first optical surface, arranged opposite to the light source, the light emitted by the light source passes through the first optical surface and enters the first prism; a second optical surface, arranged opposite to the first optical surface, a total reflection film is arranged on the second optical surface, the light passing through the first optical surface is incident on the second optical surface and is reflected on the total reflection film; a third optical surface, arranged opposite to the second optical surface, a total reflection film is arranged on the third optical surface, the light reflected from the second optical surface is incident on the third optical surface and is reflected on the total reflection film; a fourth optical surface, arranged opposite to the third optical surface, the light reflected from the third optical surface is emitted to the fourth optical surface and passes through the fourth optical surface to exit the first prism; the first optical surface, the second optical surface, the third optical surface and the fourth optical surface are curved surfaces protruding outwardly away from the center of the first prism; the second prism, arranged opposite to the first prism, The second prism comprises: a first optical surface, which is arranged opposite to the fourth optical surface, and the light emitted from the first prism enters the second prism through the first optical surface, and the first optical surface is a curved surface that is concave inwardly toward the center of the second prism; a second optical surface, which is arranged opposite to the first optical surface, and the light passing through the first optical surface is incident on the second optical surface, and its incident angle is greater than arctan (1 / n), and the light is reflected on the second optical surface, wherein n is the refractive index of the second prism under 586nm light, and the second optical surface is a curved surface that is concave inwardly toward the center of the second prism; a third optical surface, which is arranged opposite to the second optical surface, and a dichroic film or a reflective film is arranged on the third optical surface, and the light reflected on the second optical surface is emitted toward the third optical surface, and after being reflected by the dichroic film or the reflective film, it is incident on the second optical surface again, passes through the second optical surface and is emitted toward the exit pupil, forming a final image with a focal plane depth greater than 0.1m, and the third optical surface is a curved surface that protrudes outwardly toward the center of the second prism.

[0008] By adopting a free-form prism structure with a total reflection film and a beam splitter film, combined with a folded optical path design, the focal length of the system is shortened, a large field of view (diagonal field of view ≥ 35°) is achieved, and the system volume is significantly reduced. The configuration of the total reflection film and the beam splitter film optimizes the light transmission path, ensuring that the light is efficiently coupled to the human eye, forming a virtual image with a focal depth greater than 1 meter, meeting the application requirements of lightweight and wearable devices.

[0009] Preferably, when a dichroic film is disposed on the third optical surface, the optical system further comprises a third prism, and one surface of the third prism is complementary to the third optical surface so as to be closely disposed.

[0010] By adding a third prism to the third optical surface and combining it with a dichroic film, the perspective function of the system is enhanced, allowing external light to merge with the display light path to achieve an augmented reality (AR) effect while maintaining the clarity and contrast of the displayed content.

[0011] Preferably, the splitting ratio of the splitter film is 1:1.

[0012] The beam splitter film adopts a 1:1 beam splitting ratio, which balances the energy distribution of transmitted light and reflected light, ensures the uniformity of the displayed image brightness, reduces light energy loss, and improves the optical efficiency of the system.

[0013] Preferably, a coordinate system is formed with the exit pupil center as the origin O, the direction toward the second prism and coinciding with the optical axis as the Z axis, the direction perpendicular to the Z axis as the Y axis, and the direction perpendicular to the ZOY plane as the X axis. The distance range between the first optical surface and the origin O is 18.8mm~22.8mm, the Y eccentricity range is 8mm~14mm, and the inclination angle range with the XOY plane is 46°~56°; the distance range between the second optical surface and the origin O is 14mm~19mm; the Y eccentricity range is 1mm~5mm, and the inclination angle range with the XOY plane is ±5°; the distance range between the third optical surface and the origin O is 20mm~24mm, the Y eccentricity range is -2mm~+2mm, and the inclination angle range with the XOY plane is -32°~-22°.

[0014] By limiting the position, eccentricity range and tilt angle of each optical surface of the second prism in the coordinate system, the light propagation path is precisely controlled, off-axis aberrations (such as coma and astigmatism) are effectively corrected, and the imaging quality is improved while ensuring the compactness of the system structure.

[0015] Preferably, the Z eccentricity range of the first optical surface is 25mm~31mm, the Y eccentricity range is 19mm~26mm, and the inclination angle range with the XOY plane is -46°~-36°; the Z eccentricity range of the second optical surface is 18mm~25mm, the Y eccentricity range is 17mm~25mm, and the inclination angle range with the XOY plane is -16°~-6°; the Z eccentricity range of the third optical surface is 25mm~31mm, the Y eccentricity range is 19mm~26mm, and the inclination angle range with the XOY plane is 27°~37°; the Z eccentricity range of the fourth optical surface is 20mm~26mm, the Y eccentricity range is 12mm~18mm, and the inclination angle range with the XOY plane is 45°~55°.

[0016] The geometric parameters of each optical surface of the first prism are further defined, the optical path folding design is optimized, stray light interference is reduced, system distortion is reduced (eg, optical distortion <8%), and the stability and clarity of the virtual image surface are ensured.

[0017] Preferably, the Z eccentricity range of the light emitting surface of the light source is 29 mm to 36 mm, the Y eccentricity range is 12 mm to 18 mm, and the inclination angle range with respect to the XOY plane is -27° to -18°.

[0018] The position parameter design of the light source's emitting surface (Z / Y eccentricity and tilt angle) matches the prism optical path to prevent the light incident angle from deviating from the designed range, thereby improving light energy utilization and suppressing ghost images.

[0019] Preferably, the focal lengths of the first prism and the second prism are no greater than 13 mm, and the focal plane depth of the final image ranges from 100 mm to 100,000 mm.

[0020] By limiting the prism focal length to ≤13mm and combining it with the focal plane depth range (100mm~100000mm), the system has both short-focus characteristics and adjustable virtual image depth, making it suitable for a variety of scenarios such as near-eye display, AR / VR, etc.

[0021] Preferably, when observed at the exit pupil position, the diagonal field of view of the optical system is not less than 35°; the field angle in the horizontal direction should be at least greater than 30°; and the exit pupil diameter of the system should be not less than 7 mm.

[0022] The design of diagonal field of view ≥35° and horizontal field of view ≥30° expands the user's field of view and enhances the sense of immersion; the exit pupil diameter ≥7mm adapts to different users' pupil distances and enhances wearing comfort.

[0023] Preferably, the first optical surface, the second optical surface and the third optical surface are all aspherical surfaces, and the material of the second prism is moldable low-melting-point glass or injection-molded optical resin material.

[0024] The second prism adopts an aspherical optical surface and a low-melting-point glass / optical resin material, which simplifies the manufacturing process (such as molding or injection molding), reduces production costs, and ensures optical surface accuracy and system stability.

[0025] Preferably, the first optical surface, the second optical surface, the third optical surface and the fourth optical surface are all aspherical surfaces, and the material of the first prism is moldable low-melting-point glass or injection-molded optical resin material.

[0026] The aspheric design and low-cost material selection of the first prism further reduce system complexity and manufacturing costs. At the same time, the off-axis aberration is corrected by the free-form surface to achieve a balance between high performance and lightweight.

[0027] Compared with the prior art, the present invention arranges the four optical surfaces of the first prism so that they protrude away from the center of the prism to facilitate shortening the focal length. At the same time, a reflective film or a spectroscopic film is attached to the first prism to shorten the focal length of the system by folding the optical path, thereby reducing the volume and increasing the field of view. In addition, by establishing a coordinate system to clarify the relative position relationship between each optical element and the optical surface, the off-axis aberration is effectively corrected, the imaging quality is improved, the stray light interference is reduced, the system distortion is reduced, and the user needs are met as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of 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 ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1 is a schematic diagram of the optical path structure of the optical system in an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of light transmission when a viewer is viewing according to an embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of an optical system in a coordinate system in an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of the incident angle when light enters the second prism from the first prism in an embodiment of the present invention;

[0033] Figure 5 It is a partial structural schematic diagram of the third prism and the second prism in an embodiment of the present invention;

[0034] Figure 6 A schematic diagram of an optical system in one implementation manner in an embodiment of the present invention;

[0035] Figure 7 This is a schematic diagram of a sampling field MTF curve of an optical system in one implementation manner in an embodiment of the present invention;

[0036] Figure 8 A schematic diagram of a distortion grid of an optical system in one implementation manner of an embodiment of the present invention;

[0037] Fig. 9 is a schematic diagram of an optical system in yet another implementation manner in an embodiment of the present invention;

[0038] Fig.10 This is a schematic diagram of a sampling field MTF curve of an optical system in yet another implementation manner in an embodiment of the present invention;

[0039] Fig.11 This is a schematic diagram of a distortion grid of an optical system in yet another implementation manner in an embodiment of the present invention.

[0040] Reference numerals:

[0041] 1. Light source; 2. First prism; 3. Second prism; 4. First optical surface; 5. Second optical surface; 6. Third optical surface; 7. Fourth optical surface; 8. First optical surface; 9. Second optical surface; 10. Third optical surface; 11. Exit pupil; 12. Flat panel display; 13. Flat glass; 14. Third prism. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection, which can be a mechanical connection, or an electrical connection, which can be a direct connection, or can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The terms "top", "bottom", "above", "lower", and "on" used throughout the description are relative to the relative positions of components of a device, such as the relative positions of the top and bottom substrates within a device. It is understood that devices are multifunctional regardless of their orientation in space.

[0045] To facilitate understanding of the embodiments of the present invention, specific embodiments will be further explained below in conjunction with the accompanying drawings. The embodiments do not constitute a limitation on the embodiments of the present invention.

[0046] This embodiment provides an optical system such as Figure 1-Figure 3 shown.

[0047] The optical system includes a light source 1 , a first prism 2 and a second prism 3 .

[0048] The light source 1 emits light to serve as the light source of the optical system.

[0049] Furthermore, the light source 1 includes a flat panel display 12 and a flat glass 13. The flat glass 13 is arranged in front of the flat panel display 12 to protect the light-emitting surface from being damaged.

[0050] The first prism 2 is arranged opposite to the light source 1. The first prism 2 includes a first optical surface 4, a second optical surface 5, a third optical surface 6 and a fourth optical surface 7. The first optical surface 4, the second optical surface 5, the third optical surface 6 and the fourth optical surface 7 are curved surfaces protruding outward away from the center of the first prism 2, thereby effectively shortening the focal length to increase the field of view.

[0051] The first optical surface 4 is arranged opposite to the light source 1 , and the light emitted by the light source 1 is transmitted through the first optical surface 4 and enters the first prism 2 .

[0052] The second optical surface 5 is arranged opposite to the first optical surface 4, and a total reflection film is arranged on the second optical surface 5, so that the light incident on the second optical surface 5 is reflected on the surface. The light transmitted through the first optical surface 4 is emitted to the second optical surface 5 and is reflected by the total reflection film.

[0053] The third optical surface 6 is arranged opposite to the second optical surface 5, and a total reflection film is also arranged on the third optical surface 6 to reflect the light incident to the third optical surface 6. The light reflected by the second optical surface 5 is incident to the third optical surface 6 and is emitted under the action of the total reflection film.

[0054] The fourth optical surface 7 is disposed opposite to the third optical surface 6 , and the light reflected by the third optical surface 6 is projected through the fourth optical surface 7 and output to the outside of the first prism 2 .

[0055] Since the optical system is an off-axis system, in order to correct off-axis aberrations, the above surfaces are described by free-form surfaces. In order to reduce the manufacturing difficulty of the system, the material of the first prism 2 can be selected from moldable low-melting-point glass or injection-molded optical resin material.

[0056] The second prism 3 is arranged opposite to the first prism 2. The second prism 3 includes a first optical surface 8, a second optical surface 9 and a third optical surface 10. The first optical surface 8 and the second optical surface 9 are curved surfaces that are concave inward toward the center of the second prism 3, and the third optical surface 10 is a curved surface that is protruding outward toward the center of the second prism 3, so as to correct aberrations to a certain extent.

[0057] The first optical surface 8 is disposed opposite to the fourth optical surface 7 , and the light projected through the fourth optical surface 7 will be incident on the first optical surface 8 and then enter the second prism 3 .

[0058] The second optical surface 9 is arranged opposite to the first optical surface 8. The light passing through the first optical surface 8 is incident on the second optical surface 9, and its incident angle satisfies the condition of total internal reflection, such as Figure 4 As shown, the incident angle is greater than arctan (1 / n), so that the light is reflected on the second optical surface 9, and n is the refractive index of the second prism 3 under 586nm light.

[0059] The third optical surface 10 is disposed opposite to the second optical surface 9 , and a beam splitting film or a reflective film is disposed on the third optical surface 10 .

[0060] The diaphragm allows a portion of the light incident thereon to continue to propagate in the form of transmission, and allows another portion of the light incident thereon to continue to propagate in the form of reflection, and the specific ratio of the reflected light to the transmitted light is determined by its own specific diaphragm ratio.

[0061] The light reflected on the second optical surface 9 is emitted toward the third optical surface 10, and after being reflected by the dichroic film or the reflective film, it is incident on the second optical surface 9 again. At this time, the incident angle of the light is less than or equal to arctan (1 / n), and it passes through the second optical surface 9 and is emitted toward the exit pupil 11, eventually forming a final image with a focal depth greater than 0.1m.

[0062] Since the optical system is an off-axis system, in order to correct off-axis aberrations, the above surfaces are described by free-form surfaces. In order to reduce the manufacturing difficulty of the system, the material of the second prism 3 can be moldable low-melting-point glass or injection-molded optical resin material.

[0063] Furthermore, when a beam splitting film is disposed on the third optical surface 10, Figure 5 As shown, a third prism 14 can also be added to the optical system as a compensation lens, and one surface of the third prism 14 is arranged in contact with the third optical surface 10 to achieve perspective without distortion, that is, external light can be emitted to the exit pupil 11 through the third prism 14 and the second prism 3. Furthermore, the splitting ratio of the dichroic film is 1:1. Through the above arrangement, the light emitted by the light source 1 can enter the exit pupil 11 to see the final image, while allowing the external light to pass through the second prism 3 to see the external environment at the position of the exit pupil 11, which has a good visual perspective experience.

[0064] Furthermore, if Figure 3 As shown, in order to describe the positions of the various optical surfaces of the optical system, a coordinate system is established with the center of the exit pupil 11 as the origin O, the direction toward the second prism 3 and coinciding with the optical axis as the Z axis, the direction perpendicular to the Z axis as the Y axis, and the direction perpendicular to the ZOY plane as the X axis.

[0065] The distance between the first optical surface 8 and the origin O is in the range of 18.8 mm to 22.8 mm, the Y eccentricity is in the range of 8 mm to 14 mm, and the inclination angle with the XOY plane is in the range of 46° to 56°.

[0066] The distance between the second optical surface 9 and the origin O is in the range of 14 mm to 19 mm; the Y eccentricity range is 1 mm to 5 mm, and the inclination angle (Alpha angle) with the XOY plane is in the range of ±5°.

[0067] The distance between the third optical surface 10 and the origin O is in the range of 20 mm to 24 mm, the Y eccentricity range is in the range of -2 mm to +2 mm, and the inclination angle range with respect to the XOY plane is in the range of -32° to -22°.

[0068] The first optical surface 4 has a Z eccentricity range of 25 mm to 31 mm, a Y eccentricity range of 19 mm to 26 mm, and an inclination angle range of -46° to -36° with respect to the XOY plane.

[0069] The Z eccentricity range of the second optical surface 5 is 18 mm to 25 mm, the Y eccentricity range is 17 mm to 25 mm, and the inclination angle range with respect to the XOY plane is -16° to -6°.

[0070] The Z eccentricity range of the third optical surface 6 is 25 mm to 31 mm, the Y eccentricity range is 19 mm to 26 mm, and the inclination angle range with respect to the XOY plane is 27° to 37°.

[0071] The fourth optical surface 7 has a Z eccentricity range of 20 mm to 26 mm, a Y eccentricity range of 12 mm to 18 mm, and an inclination angle range of 45° to 55° with respect to the XOY plane.

[0072] The Z eccentricity range of the light emitting surface of the light source 1 is 29 mm to 36 mm, the Y eccentricity range is 12 mm to 18 mm, and the inclination angle range with respect to the XOY plane is -27° to -18°.

[0073] The above relative positions can make the optical system have the best effect while maintaining the focal depth and field of view. The focal length of the free-form surface prism in the system is not greater than 13mm; the focal depth range of the system is: 100mm~100000mm; observed from the position of the system exit pupil 11, the diagonal field of view of the display light path of the system is not less than 35°; the field of view angle in the horizontal direction should be at least greater than 30°; the diameter of the system exit pupil 11 should be not less than 7mm.

[0074] A feasible implementation of this embodiment will be described in detail below to make the present disclosure sufficient and complete and to fully convey the concept of this patent to those skilled in the art.

[0075] like Figure 6The optical system shown, through the parameter characteristics of the optical system provided in Table 1, the free surface coefficients provided in Table 2, and the aspheric coefficients provided in Table 3, forms a system field angle of 35°, an exit pupil 11 diameter of 7mm, a focal depth of 2m for the final image, and a focal length of 13mm.

[0076] Table 1 Optical system parameters

[0077]

[0078] Among them, 101 represents the final image, 102 represents the exit pupil 11, 103 represents the second optical surface 9, 104 represents the third optical surface 10, 105 represents the first optical surface 8, 106 represents the fourth optical surface 7, 107 represents the third optical surface 6, 108 represents the second optical surface 5, 109 represents the first optical surface 4, 110 represents the light exit surface of the flat panel display 12, and 111 represents the flat glass 13.

[0079] Among the above surfaces, the surface constituting the free-form surface satisfies the equation: c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, C i is the coefficient of the higher-order term. The surface constituting the aspheric surface satisfies the equation: c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, A i are the coefficients of the higher-order terms.

[0080] Table 2 Free surface coefficients

[0081]

[0082] Table 3 Aspheric coefficients

[0083]

[0084]

[0085] like Figure 7 As shown in the figure, the MTF of each sampling field obtained based on the above implementation is higher than 0.2 at 30lp / mm, indicating that the imaging quality of the system is excellent, wherein the horizontal axis represents the sampling frequency of the image space, the vertical axis represents the contrast, and F1 to F9 are the sampling fields used to evaluate the display quality of the system. Figure 8 As shown, the distortion-free situation under ideal conditions is compared with the actual state after being processed by the visual optical system, and it is found that the optical distortion is less than 8% and the imaging quality is good.

[0086] Another feasible implementation of this embodiment will be provided in detail below to make the present disclosure sufficient and complete and to fully convey the concept of this patent to those skilled in the art.

[0087] like Fig. 9 The optical system shown, through the optical system parameter characteristics provided in Table 4, the free surface coefficients provided in Table 5, and the aspheric coefficients provided in Table 6, forms a system field angle of 35°, an exit pupil 11 diameter of 7mm, a final image focal depth of 2m, and a focal length of 9.5mm.

[0088] Table 4 Optical system parameters

[0089]

[0090]

[0091] Among them, 201 represents the final image, 202 represents the exit pupil 11, 203 is the second optical surface 9, 204 is the third optical surface 10, 205 is the first optical surface 8, 206 is the fourth optical surface 7, 207 is the third optical surface 6, 208 is the second optical surface 5, 209 is the first optical surface 4, 210 is the light exit surface of the flat panel display 12, and 211 is the flat glass 13.

[0092] Among the above surfaces, the surface constituting the free-form surface satisfies the equation: c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, C i is the coefficient of the higher-order term. The surface constituting the aspheric surface satisfies the equation: c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, A i are the coefficients of the higher-order terms.

[0093] Table 5 Free surface coefficients

[0094]

[0095]

[0096] like Fig.10 As shown in the figure, the MTF of each sampling field obtained based on the above implementation is higher than 0.2 at 30lp / mm, indicating that the imaging quality of the system is excellent, wherein the horizontal axis represents the sampling frequency of the image space, the vertical axis represents the contrast, and F1 to F9 are the sampling fields used to evaluate the display quality of the system. Fig.11 As shown, the distortion-free situation under ideal conditions is compared with the actual state after being processed by the visual optical system, and it is found that the optical distortion is less than 6% and the imaging quality is good.

[0097] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An optical system, characterized in that: include: Light source, emitting light; A first prism is disposed opposite to the light source, and the first prism comprises: A first optical surface is arranged opposite to the light source, and light emitted by the light source passes through the first optical surface and enters the first prism; A second optical surface is arranged opposite to the first optical surface, a total reflection film is arranged on the second optical surface, and light passing through the first optical surface is incident on the second optical surface and reflected on the total reflection film; A third optical surface is arranged opposite to the second optical surface, a total reflection film is arranged on the third optical surface, and the light reflected by the second optical surface is incident on the third optical surface and reflected on the total reflection film; A fourth optical surface is arranged opposite to the third optical surface, and the light reflected by the third optical surface is emitted toward the fourth optical surface and passes through the fourth optical surface to be emitted out of the first prism; The first optical surface, the second optical surface, the third optical surface and the fourth optical surface are curved surfaces protruding outward away from the center of the first prism; The second prism is arranged opposite to the first prism, and the second prism comprises: A first optical surface is arranged opposite to the fourth optical surface, and the light emitted from the first prism enters the second prism through the first optical surface, and the first optical surface is a curved surface that is concave inward toward the center of the second prism; A second optical surface is arranged opposite to the first optical surface, and light passing through the first optical surface is incident on the second optical surface, and its incident angle is greater than arctan (1 / n), and the light is reflected on the second optical surface, where n is the refractive index of the second prism under 586nm light, and the second optical surface is a curved surface that is concave inward toward the center of the second prism; The third optical surface is arranged opposite to the second optical surface, and a dichroic film or a reflective film is arranged on the third optical surface. The light reflected from the second optical surface is emitted toward the third optical surface, and after being reflected by the dichroic film or the reflective film, it is incident on the second optical surface again, passes through the second optical surface and is emitted toward the exit pupil, forming a final image with a focal plane depth greater than 0.1m. The third optical surface is a curved surface protruding outward toward the center of the second prism.

2. The optical system according to claim 1, characterized in that When a prismatic film is disposed on the third optical surface, the optical system further comprises a third prism, and one surface of the third prism is complementary to the third optical surface so as to be bonded together.

3. The optical system according to claim 2, characterized in that The splitting ratio of the splitter film is 1:

1.

4. The optical system according to claim 1, characterized in that A coordinate system is formed with the center of the exit pupil as the origin O, the direction toward the second prism and coinciding with the optical axis as the Z axis, the direction perpendicular to the Z axis as the Y axis, and the direction perpendicular to the ZOY plane as the X axis. The distance between the first optical surface of the second prism and the origin O is in the range of 18.8 mm to 22.8 mm, the Y eccentricity range is 8 mm to 14 mm, and the inclination angle range with the XOY plane is 46° to 56°; The distance between the second optical surface and the origin O is in the range of 14 mm to 19 mm; the Y eccentricity range is 1 mm to 5 mm, and the inclination angle range with the XOY plane is ±5°; The distance between the third optical surface and the origin O ranges from 20 mm to 24 mm, the Y eccentricity ranges from -2 mm to +2 mm, and the inclination angle range with the XOY plane ranges from -32° to -22°.

5. The optical system according to claim 4, characterized in that The first optical surface of the first prism has a Z eccentricity range of 25 mm to 31 mm, a Y eccentricity range of 19 mm to 26 mm, and an inclination angle range of -46° to -36° with respect to the XOY plane; The second optical surface has a Z eccentricity range of 18 mm to 25 mm, a Y eccentricity range of 17 mm to 25 mm, and an inclination angle range of -16° to -6° with respect to the XOY plane; The third optical surface has a Z eccentricity range of 25 mm to 31 mm, a Y eccentricity range of 19 mm to 26 mm, and an inclination angle range of 27° to 37° with respect to the XOY plane; The fourth optical surface has a Z eccentricity range of 20 mm to 26 mm, a Y eccentricity range of 12 mm to 18 mm, and an inclination angle range of 45° to 55° with respect to the XOY plane.

6. The optical system according to claim 4, characterized in that The Z eccentricity range of the light emitting surface of the light source is 29 mm to 36 mm, the Y eccentricity range is 12 mm to 18 mm, and the inclination angle range with the XOY plane is -27° to -18°.

7. The optical system according to claim 1, characterized in that The combined focal length of the first prism and the second prism is no more than 13 mm, and the focal plane depth of the final image ranges from 100 mm to 100,000 mm.

8. The optical system according to claim 1, characterized in that When observed at the exit pupil position, the diagonal field of view of the optical system shall not be less than 35°; the horizontal field angle shall be at least greater than 30°; and the exit pupil diameter of the system shall not be less than 7mm.

9. The optical system according to claim 1, characterized in that The first optical surface, the second optical surface and the third optical surface are all aspherical surfaces, and the material of the second prism is moldable low-melting-point glass or injection-molded optical resin material.

10. The optical system according to claim 1, characterized in that The first optical surface, the second optical surface, the third optical surface and the fourth optical surface are all aspherical surfaces, and the material of the first prism is moldable low-melting-point glass or injection-molded optical resin material.

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