WO2019033748A1

WO2019033748A1 - Imaging system based on dual-free-form surface reflection and augmented reality device

Info

Publication number: WO2019033748A1
Application number: PCT/CN2018/078726
Authority: WO
Inventors: 刘洋; 朱耀明; 张韦韪
Original assignee: 深圳惠牛科技有限公司
Priority date: 2017-08-18
Filing date: 2018-03-12
Publication date: 2019-02-21
Also published as: CN107300777A; DE212018000009U1

Abstract

Provided are an imaging system based on dual-free-form surface reflection and an augmented reality device. The imaging system based on dual-free-form surface reflection comprises an image source (1), a projection lens (2), a first free-form surface (3) and a second free-form surface (4) successively arranged along an optical path, wherein the first free-form surface (3) and the second free-form surface (4) are both half-reflective and half-transparent lenses, and are used for partially reflecting and partially transmitting light rays; the light rays emitted by the image source (1) successively pass through the projection lens (2) and the first free-form surface (3), then arrive at the second free-form surface (4), and same are reflected there; after being transmitted by the second free-form surface (4), external light rays (6) are superposed with the light rays reflected by the second free-form surface (4); and the superposed light rays arrive at the first free-form surface (3) and arrive at a human eye (5) after being transmitted by the first free-form surface (3).

Description

Imaging system based on double free-form surface reflection and augmented reality device

Technical field

The present invention relates to the field of optical design technology, and more particularly to an imaging system and augmented reality device based on double free-form surface reflection.

Background technique

Augmented Reality (AR) is a technology that uses computer systems to generate virtual image information to increase user perception of the real world. Unlike the fully immersive effect achieved by virtual reality technology, Augmented Reality is dedicated to superimposing computer-generated virtual objects, images, texts and other information into real scenes, creating a world of virtual and real, and through image recognition, tracking and registration. Technology, cloud technology, etc. realize the interaction of virtual and real scenes, thus realizing the "enhancement" of the real world.

In recent years, with the continuous advancement of technologies such as microelectronics, optoelectronics, and optical design, the original heavy-duty helmet-type display system has gradually developed into a wearable smart glasses system with low power consumption, light weight, and small size ( Also known as video glasses, it has become the top priority of wearable technology. Augmented reality glasses are used in applications ranging from defense and aerospace to a variety of industry scenarios and general consumer applications.

The augmented reality smart glasses system is mainly composed of an image display source, an optical imaging system, a positioning sensing system, a circuit control, a connection system, a weight system and the like. The performance of the optical system not only affects the imaging effect of the image source, but also has a close relationship with the size, weight and feeling of use of the smart glasses. Augmented reality glasses often use a penetrating light path. The wearer sees the virtual image formed by the image source through magnification and aberration correction. The virtual image is imaged at a position of 3 meters in front of the eye. The wearer can simultaneously obtain the virtual information of the image source and the outside. The real information of the scene.

The optical system needs to comprehensively consider the coordination of the parameters such as field of view, brightness, exit distance, exit pupil diameter, binocular distance, aberration and magnification, and overall volumetric weight and cost. From the existing optical path design solutions in the industry, such as Google's Google-glass prism reflective light path, Microsoft's Hololens glasses holographic grating waveguide light path, Israel Lumus's stacked array geometric waveguide solution and Beijing Institute of Technology's free-form surface Prism scheme, etc.; at the same time, the optimal optical parameters and compact size and weight are difficult and challenging.

Intelligent glasses using geometric waveguides or holographic waveguide schemes use the total internal reflection and grating diffraction of light in a planar waveguide element to effectively reduce the thickness of the optical element, but the planar waveguide element does not provide power and requires complex relaying. Light path use.

In the design of imaging optical system, the application advantages of free-form surface in imaging optical system are constantly reflected, and it has gradually become a research hotspot in the field of imaging optics. The near-eye display scheme of the free-form surface prism is as follows: the image of the micro-projection screen projects a virtual scene in front of the human eye through the refraction and total reflection of the three free-form surfaces of the optical free-form surface prism, and realizes position fusion with the real object. Since the free-form surface prism itself has power and high aberration correction ability, the virtual image after magnification and aberration correction is obtained, but the imaging prism will significantly shift the light of the real scene, causing huge aberrations, requiring The compensation prism compensates. The use of the compensating prism causes the volume of the optical path portion to become bulky, which limits further thinning.

The above shortcomings need to be improved.

technical problem

An object of the present invention is to provide an imaging system based on double free-form surface reflection to solve the technical problem that the optical path in the prior art is bulky and difficult to achieve thinning.

Technical solution

In order to solve the above technical problem, the technical solution adopted by the embodiment of the present invention is to provide an imaging system based on double free-form surface reflection, which is sequentially disposed along the optical path:

An image source for transmitting image light carrying image information;

a projection lens for transmitting and adjusting a direction of propagation of the image light;

a first free curved surface for partially reflecting and partially transmitting the image light and the external light;

a second free curved surface for partially reflecting and partially transmitting the image light and the external light;

The image light passes through the projection lens and the first free curved surface to reach the second free curved surface and is reflected;

The external light is transmitted through the second free curved surface and superimposed on the image light reflected by the second free curved surface;

The superimposed light reaches the first free curved surface and is transmitted through the first free curved surface to reach the human eye.

Further, the first free curved surface is an optical plastic lens or an optical glass lens, and the second free curved surface is an optical plastic lens or an optical glass lens.

Further, the first free curved surface has a thickness of not more than 1.5 mm, and the second free curved surface has a thickness of not more than 1.5 mm.

Further, an upper surface and/or a lower surface of the projection lens is provided with an anti-reflection film.

Further, an upper surface of the first free curved surface is provided with an anti-reflection film, and an upper surface of the first free curved surface is provided with an anti-reflection film.

Further, the surface of the second free curved surface facing the first free curved surface is provided with an anti-reflection film, and the surface of the second free curved surface facing away from the first free curved surface is provided with an anti-reflection film.

Further, a surface of the second free curved surface facing away from the first free curved surface is provided with a photochromic layer.

Further, the photochromic layer is a silver halide microcrystal layer.

Further, the incident angle of the incident light of the first free curved surface ranges from 45° to 60°.

Further, an incident angle of the incident light of the second free curved surface ranges from 15° to 25°.

Further, the image source comprises an LCD, OLED, DLP or LCoS type microdisplay.

Further, the first free curved surface and the second free curved surface are both bivariate orthogonal polynomial free surfaces, and the specific expression is:

Where c is the surface curvature; k is the quadratic aspheric constant; c _mn is the coefficient of the different order, and p is the highest power of the polynomial, satisfying 1 ≤ m + n ≤ p.

Further, the first free-form surface and the second free-form surface are Zernike polynomial free-form surfaces, and the specific expression is:

Where Z(x, y) is the vector height of the optical surface, the first term in the formula is the conical surface portion, c is the surface curvature, and k is the quadratic aspheric constant, the second term in the formula is Zernike polynomial, A _i is the Zernike polynomial coefficient, E _i is the Zernike polynomial, and ρ and θ are the variables of the Zernike polynomial, respectively.

Further, the first free curved surface and the second free curved surface are toric surfaces, and the mathematical description equation is as follows:

Where c _x is the radius of curvature of the surface in the XZ plane, c _y is the radius of curvature of the surface in the YZ plane, k _x is the quadric surface coefficient of the surface in the sagittal direction, and k _y is the quadratic surface of the surface in the meridional direction The surface coefficient, A _i is an aspheric coefficient that is rotationally symmetric about the Z axis, and B _i is a non-rotational symmetry coefficient.

It is also an object of embodiments of the present invention to provide an augmented reality device comprising the above-described dual free-form surface reflection based imaging system.

Beneficial effect

An advantageous effect of an imaging system based on double free-form surface reflection provided by an embodiment of the present invention is:

(1) By providing a first free-form surface and a second free-form surface, which has the same ability to correct virtual image aberration as the free-form surface prism, and the overall volume is lighter, which is advantageous for thinning and thinning.

(2) The external light can enter the imaging system through the second free-form surface and overlap with the image light. The human eye has almost no distortion and aberration when observing the external image, so it is no longer necessary to compensate the real scene with the compensation prism. The image quality is optimized, and the overall volume is lighter, which is more conducive to thinning.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments or the description of the prior art will be briefly described below. It is obvious that the drawings in the following description are only the present invention. For some embodiments, other drawings may be obtained from those of ordinary skill in the art without departing from the drawings.

FIG. 1 is a schematic structural diagram of an imaging system based on double free-form surface reflection according to an embodiment of the present invention.

Among them, the various reference numerals in the figure:

1-image source; 2-projection lens;

3-first free curved surface; 4-second free curved surface;

5- human eye; 6- outside light.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

It should be noted that when a component is referred to as being "fixed" or "in" another component, it can be directly or indirectly located on the other component. When a component is referred to as being "connected" to another component, it can be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. The orientation or position of the indication is based on the orientation or position shown in the drawings, and is merely for convenience of description and is not to be construed as limiting the technical solution. The terms "first" and "second" are used for convenience of description only, and are not to be understood as indicating or implying a relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless specifically defined otherwise.

Referring to FIG. 1, an imaging system based on double free-form surface reflection includes an image source 1, a projection lens 2, a first free-form surface 3, and a second free-form surface 4, which are sequentially disposed along an optical path, wherein the image source 1 is used for transmitting and carrying The image light of the image information, the projection lens 2 is used for projecting and adjusting the propagation inversion of the image light, and the first free curved surface 3 is a semi-reflexive half lens for partially reflecting and partially transmitting the image light and the external light, second The freeform surface 4 is a semi-reflexive half lens sheet for partial reflection and partial transmission of image light and external light. The image light emitted by the image source 1 passes through the projection lens 2 and the first free curved surface 3 to reach the second free curved surface 4 and is reflected, and the external light 6 is transmitted through the second free curved surface 4 and the image reflected by the second free curved surface 4. The light rays are superimposed, and the superimposed light reaches the first free curved surface 3 and is transmitted through the first free curved surface 3 to reach the human eye 5.

The working principle of an imaging system based on double free-form surface reflection provided by this embodiment is as follows: when the user needs to view an image, the image source 1 starts to work, and the image light emitted by the image source 1 passes through the projection lens 2 and the first free curved surface in sequence. 3, after reaching the second free-form surface 4 and reflecting on the surface of the second free-form surface 4, the external light 6 is transmitted through the second free-form surface 4 and superimposed with the image light reflected by the second free-form surface 4, and the superimposed light reaches the first The free-form surface 3 is transmitted through the first free-form surface 3 and reaches the human eye 5, so that the user can view the image of the virtual-solid superposition, that is, the image emitted by the image source 1 and the image formed by the superposition of the external image.

The beneficial effects of an imaging system based on double free-form surface reflection provided by this embodiment are as follows:

(1) By providing the first free-form surface 3 and the second free-form surface 4, which has the same ability to correct virtual image aberration as the free-form surface prism, and the overall volume is lighter, which is advantageous for thinning and thinning.

(2) The external light 6 can enter the imaging system through the second free-form surface 4 to be superimposed with the image light, and the human eye 5 has almost no distortion and aberration when observing the external image, so that it is no longer necessary to use the compensation prism to perform the real scene. Compensation not only optimizes the image quality, but also makes the overall volume lighter and more conducive to lighter and thinner.

In one embodiment, the surface parameters of the first freeform surface 3 can be optimized according to the imaging quality of the virtual image such that the meridional plane (the plane of the principal ray and the optical axis determined by the object point) and the sagittal plane (through the chief ray) The aberration of the plane perpendicular to the meridian plane is corrected to improve the image quality.

Further, the first free curved surface 3 is an optical plastic lens or an optical glass lens, and the thickness of the first free curved surface 3 is not more than 1.5 mm, so that when the external light 6 is transmitted through the first free curved surface 3, no distortion is generated, ensuring The external light 6 viewed by the human eye 5 is not distorted.

Further, the second free curved surface 4 is an optical plastic lens or an optical glass lens, and the thickness of the second free curved surface 4 is not more than 1.5 mm, so that when the external light 6 is transmitted through the second free curved surface 4, no distortion is generated, ensuring The external light 6 viewed by the human eye 5 is not distorted.

Further, the upper surface and/or the lower surface of the projection lens 2 is provided with an anti-reflection film, so that the reflectance to light can be improved. The thickness of the antireflection film can be optimized as needed.

In one embodiment, the upper surface of the projection lens 2 is provided with an anti-reflection film, so that the reflectivity to ambient stray light can be improved, so that ambient stray light cannot enter the projection lens 2, and the influence of environmental stray light is avoided.

In one embodiment, the lower surface of the projection lens 2 is provided with an anti-reflection film, so that the reflectance to the light can be increased, so that the light reflected from the first free-form surface 3 cannot enter the projection lens 2, avoiding this part. The effect of light.

In one embodiment, the upper surface of the projection lens 2 is provided with an anti-reflection film, and the lower surface of the projection lens 2 is also provided with an anti-reflection film, which avoids the influence of ambient stray light and light reflected from the first free curved surface 3. .

In one embodiment, the upper surface of the first free curved surface 3 is provided with an anti-reflection film, which is beneficial for the light emitted by the image source 1 to be effectively reflected to the second free-form surface 4 after reaching the first free-form surface 3, thereby improving the light. The utilization rate is beneficial to improve the brightness of the image. The thickness of the antireflection film can be optimized according to the range of incident angles incident on the first free curved surface 3.

In one embodiment, the lower surface of the first free curved surface 3 is provided with an anti-reflection film, which facilitates transmission of light passing through the second free curved surface 4 to the first free curved surface 3, thereby improving the utilization of the light and facilitating the improvement. The brightness of the image. The thickness of the antireflection film can be optimized according to the range of incident angles incident on the first free curved surface 3.

In one embodiment, the upper surface of the first free curved surface 3 is provided with an anti-reflection film, which is beneficial for the light emitted by the image source 1 to be effectively reflected to the second free-form surface 4 after reaching the first free-form surface 3; The lower surface of the 3 is provided with an anti-reflection film, which facilitates the transmission of the light passing through the second free-form surface 4 to the first free-form surface 3, thereby improving the utilization of the light and improving the brightness of the image. The thickness of the antireflection film can be optimized according to the range of incident angles incident on the first free curved surface 3, and the thickness of the antireflection film can be optimized according to the range of incident angles incident on the first free curved surface 3.

In an embodiment, the second free-form surface 4 is provided with an anti-reflection film toward the surface of the first free-form surface 3, which is beneficial for the light emitted by the image source 1 to be effectively reflected to the first free-form surface 3 after reaching the second free-form surface 4. Thereby, the utilization of light is improved, which is advantageous for improving the brightness of imaging. The thickness of the antireflection film can be optimized according to the range of incident angles incident on the second free curved surface 4.

In one embodiment, the surface of the second free curved surface 4 facing away from the first free curved surface 3 is provided with an anti-reflection film, which facilitates the transmission of the external light 6 through the second free curved surface 4 into the imaging system, thereby improving the utilization of the light. Helps to increase the brightness of the image. The thickness of the antireflection film can be optimized according to the range of incident angles incident on the second free curved surface 4.

In one embodiment, in an embodiment, the second free-form surface 4 is provided with an anti-reflection film toward the surface of the first free-form surface 3, which is beneficial for the light emitted by the image source 1 to be effectively reflected after reaching the second free-form surface 4. The first free-form surface 3; at the same time, the surface of the second free-form surface 4 facing away from the first free-form surface 3 is provided with an anti-reflection film, which is favorable for the external light 6 to be transmitted through the second free-form surface 4 to the imaging system, thereby improving the utilization of light. It is beneficial to improve the brightness of the image. The thickness of the antireflection film can be optimized according to the range of incident angles incident on the second free curved surface 4, and the thickness of the antireflection film can be optimized according to the range of incident angles incident on the second freeform surface 4.

In one embodiment, the light emitted by the image source 1 mainly refers to light in the visible light band, and the external light 6 also mainly refers to light in the visible light band.

Further, a surface of the second free curved surface 4 facing away from the first free curved surface 3 is provided with a photochromic layer. Photochromism refers to the reversible process in which the absorption spectrum of a photochromic material changes when exposed to a specified wavelength. Photochromic materials include silver halide systems, diarylethene, fulgide, spiropyran, spiroazine, azo, and related heterocyclic compounds. When the second free-form surface 4 having the photochromic layer is in a strong sunlight environment, the second optical lens 41 is irradiated with short-wavelength light such as ultraviolet rays, and the color of the second free-form surface 4 is uniformly deepened. The transmittance of the second free-form surface 4 to the external light 6 is reduced, so that the amount of light entering the imaging system through the second free-form surface 4 is reduced, so that the user can still use the light in a relatively strong environment; When the light 6 is dark, the color of the second free curved surface 4 becomes shallow, and the transmittance of the second free curved surface 4 to the external light 6 is increased, so that the amount of light entering the imaging system through the ambient light is increased, so that the user is in the light. It can still be used normally in a darker environment.

In one embodiment, the photochromic layer is a silver halide microcrystal layer, and the silver halide microcrystal layer may be attached to the surface of the second freeform surface 4 by an adsorption process. Under the strong sunlight and ultraviolet light, the silver halide microcrystal layer can completely absorb ultraviolet light and darken rapidly, and it is neutral to visible light. When the external light 6 becomes dark, the silver halide microcrystal layer can quickly recover to It is colorless and transparent, so it does not need to change the transmitted light intensity adaptively by frequently changing the filter, which improves the contrast and observation effect of the super-real scene overlay.

Further, the angle of the light reaching the first free curved surface 3 after being transmitted through the projection lens 2 and the central axis of the first free curved surface 3 is in the range of 45° to 60°, that is, the incident angle of the incident light of the first free curved surface 3 The range is 45° to 60°. The angle between the light that is reflected by the first free curved surface 3 and reaches the second free curved surface 4 and the central axis of the second free curved surface 4 ranges from 15° to 25°, that is, the range of the incident angle of the incident light of the second free curved surface 4 It is 15 ° ~ 25 °.

Further, the image source 1 includes an LCD (Liquid Crystal Display), an OLED (Organic Light-Emitting Diode), a DLP (Digital Light Processing), or an LCoS (Liquid Crystal ON Silicon). Liquid crystal) type microdisplay. For autonomous illuminating screens such as OLEDs, they can be placed directly on the object surface, while microdisplay elements such as LCoS and DLP are of the passive illuminating type, requiring a PBS (Polarization Beam Splitter) prism or a PBS spectroscopic film. In this embodiment, the image plane position is matched with the image display position of the OLED micro display element, and can be directly applied; the LCoS microdisplay, after the PBS prism is added, the image display position of the LCoS micro display element and the image display position of the LCoS micro display element can be performed as needed. Adjustment.

Further, the first free curved surface 3 and the second free curved surface 4 can be processed by using a diamond turning machine, and only the surface type error needs to be ensured during the processing; the relative position of the optical path components of the optical system is fixed by the specially designed structural fixing member. . In this way, there is a certain degree of assembly freedom to adjust the structural error, which can achieve very low structural errors, and the processing difficulty and assembly difficulty are greatly reduced.

In one embodiment, the first freeform surface 3 and the second freeform surface 4 are bivariate orthogonal polynomial freeform surfaces (also referred to as XY polynomial freeform surfaces), and the specific expression is:

Where c is the surface curvature; k is the quadratic aspheric constant; c _mn is the coefficient of the different order, p is the highest power of the polynomial, m, n, p are preferably integers, satisfying 1 ≤ m + n ≤ p. Select the even power x term to ensure the symmetry of the face shape with respect to the YZ plane.

In one embodiment, the first freeform surface 3 and the second freeform surface 4 are Zernike polynomial freeform surfaces (also known as Zernike polynomial freeform surfaces), and the specific expression is:

Where Z(x, y) is the vector height of the optical surface, the first term of the above formula is the conical surface (ie the Conic surface) part, c is the surface curvature, k is the quadratic aspheric constant, the second term of the above formula Is the Zernike polynomial, A _i is the Zernike polynomial coefficient, E _i is the Zernike polynomial, and ρ and θ are the variables of the Zernike polynomial, respectively.

In one embodiment, the first freeform surface 3 and the second freeform surface 4 are toric surfaces, and the mathematical description equation is as follows:

In one embodiment, the parameters of the respective optical surfaces are as shown in Tables 1 and 2 below.

Table 1 optical component parameter table

The first lens surface is the upper surface of the projection lens 2, and the second lens surface is the lower surface of the projection lens 2.

Table 2 optical freeform surface parameter table

It is also an object of the present embodiment to provide an augmented reality device comprising the above-described imaging system based on double free-form surface reflection. By providing the first free-form surface 3 and the second free-form surface 4, it has the same ability to correct the virtual image aberration as the free-form surface prism, and the overall volume is lighter, which is advantageous for thinning and thinning. The external light 6 can be superimposed on the light source of the image source through the second free curved surface 4, and the human eye 5 has almost no distortion and aberration when observing the external image, so that it is no longer necessary to compensate the real scene by using the compensation prism. Not only the image quality is optimized, but also the overall volume is lighter, which is more conducive to lighter and thinner.

The above is only the embodiments of the present invention, and is not intended to limit the present invention. Any modifications, equivalents, and improvements made within the spirit and scope of the present invention should be included in the scope of the present invention. Inside.

Claims

An imaging system based on double free-form surface reflection, comprising: sequentially arranged along an optical path:

An image source for transmitting image light carrying image information;

a projection lens for transmitting and adjusting a direction of propagation of the image light;

a first free curved surface for partially reflecting and partially transmitting the image light and the external light;

a second free curved surface for partially reflecting and partially transmitting the image light and the external light;

The image light passes through the projection lens and the first free curved surface to reach the second free curved surface and is reflected;

The external light is transmitted through the second free curved surface and superimposed on the image light reflected by the second free curved surface;

The superimposed light reaches the first free curved surface and is transmitted through the first free curved surface to reach the human eye.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the first free curved surface is an optical plastic lens or an optical glass lens, and the second free curved surface is an optical plastic lens or an optical glass lens.
The dual free-form surface reflection-based imaging system according to claim 2, wherein the first free curved surface has a thickness of not more than 1.5 mm, and the second free curved surface has a thickness of not more than 1.5 mm.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the upper surface and/or the lower surface of the projection lens is provided with an anti-reflection film.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the upper surface of the first free curved surface is provided with an anti-reflection film, and the lower surface of the first free curved surface is provided with an anti-reflection film.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the second free curved surface is provided with an anti-reflection film facing the surface of the first free-form surface, and the second free-form surface is facing away from the surface The surface of the first free curved surface is provided with an anti-reflection film.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the surface of the second free curved surface facing away from the first free curved surface is provided with a photochromic layer.
The dual free-form surface reflection based imaging system of claim 7 wherein said photochromic layer is a silver halide microcrystal layer.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the incident angle of the first free curved surface has an incident angle ranging from 45° to 60°.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the incident angle of the second free curved surface has an incident angle ranging from 15° to 25°.
The dual free-form surface reflection based imaging system of claim 1 wherein said image source comprises an LCD, OLED, DLP or LCoS type microdisplay.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the first free-form surface and the second free-form surface are bivariate orthogonal polynomial free-form surfaces, and the specific expression is:

Where c is the surface curvature; k is the quadratic aspheric constant; c mn is the coefficient of the different order, and p is the highest power of the polynomial, satisfying 1 ≤ m + n ≤ p.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the first free curved surface and the second free curved surface are Zernike polynomial free-form surfaces, and the specific expression is:

Where Z(x, y) is the vector height of the optical surface, the first term in the formula is the conical surface portion, c is the surface curvature, and k is the quadratic aspheric constant, the second term in the formula is Zernike polynomial, A i is the Zernike polynomial coefficient, E i is the Zernike polynomial, and ρ and θ are the variables of the Zernike polynomial, respectively.
The dual free-form surface reflection-based imaging system according to claim 1, wherein the first free curved surface and the second free curved surface are toric surfaces, and the mathematical description equation is as follows:

Where c x is the radius of curvature of the surface in the XZ plane, c y is the radius of curvature of the surface in the YZ plane, k x is the quadric surface coefficient of the surface in the sagittal direction, and k y is the quadratic surface of the surface in the meridional direction The surface coefficient, A i is an aspheric coefficient that is rotationally symmetric about the Z axis, and B i is a non-rotational symmetry coefficient.
An augmented reality device comprising the dual free-form surface reflection-based imaging system of any one of claims 9-14.