Optical system of augmented reality head-up display

Abstract

An optical system includes an image generating unit; the correction optical unit is configured to generate monotonous change of the optical path length of the light rays propagating from the image generation unit in the horizontal field-of-view direction; and a combiner configured to redirect the light propagating from the correction optical unit to the eyebox, thereby producing one or more virtual images observable from the eyebox. The optical system provides a virtual image surface inclined in a horizontal field-of-view direction for displaying a virtual image. Projections of the virtual image surface on a horizontal plane have a non-zero angle, and the horizontal plane is defined by a first axis perpendicular to the virtual image surface and extending through any intersection point on the virtual image surface and a second axis parallel to the line of sight and extending from the eye square box through the intersection point.

Description

Background Art

[0001] The optical system of a see-through head-up display provides the ability to present information and graphics to an observer without requiring the observer to look away from a given viewpoint or otherwise refocus his or her eyes. In such systems, the observer views an external scene through a combiner. The combiner allows light from the external scene to pass through while also redirecting the image artificially produced by the projector so that the observer can see both the external light and the projected image. The projected image may include one or more virtual objects to enhance the observer's view of the external scene, which is also known as augmented reality (AR). BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Figure 1 A block diagram of an AR display environment including an optical system according to an embodiment of the present disclosure is provided.

[0003] Figure 2 Yes, according to some embodiments of the present disclosure, Figure 1 Schematic diagram of the optical system.

[0004] Figure 3 Yes, according to the embodiment of the present disclosure, the horizontal field of view is tilted and Figure 1 and Figure 2 Top view of the virtual image surface produced by the optical system.

[0005] Figure 4A and Figure 4B Yes, according to the examples disclosed herein, Figure 1 Schematic diagram of the correction optical unit of the optical system.

[0006] Figure 5 Yes, according to some embodiments of the present disclosure, by Figure 1 The front view and the top view of the virtual image surface which is tilted in the horizontal field of view direction and produced by the optical system.

[0007] Figure 6 According to the embodiment of the present disclosure, Figure 1 Paradigm transformation of the local coordinate system in which the elements of an optical system have a spatial relationship.

[0008] Figure 7 According to some embodiments of the present disclosure, Figure 1 Estimation of stereo depth of field for optical systems.

[0009] Figure 8 According to some embodiments of the present disclosure, Figure 1 An estimate of the usable size of a virtual object produced by an optical system without being perceived as tilted.

[0010] Fig.9A and Fig. 9B According to the embodiment of the present disclosure, Figure 1 , 4A and example design parameters for the optical system of 4B.

[0011] Fig. 10A and Fig. 10B According to an embodiment of the present disclosure, the Figure 4A and Figure 4B Correction optical unit Figure 1 Example holographic optical element (HOE) recording parameters of an optical system combiner.

[0012] Fig.11A and Fig. 11B Yes, according to another example of the present disclosure, Figure 1 Schematic diagram of the correction optical unit of the optical system.

[0013] Fig. 12A According to the embodiment of the present disclosure, in the Fig.11A and Fig. 11B Correction optical unit Figure 1 Surface sag of an example optical component surface in a direction perpendicular to the field of view of the optical system.

[0014] Fig. 12B According to the embodiment of the present disclosure, in the Fig.11A and Fig. 11B Correction optical unit Figure 1 Surface sag of an example optical element surface in the horizontal field of view direction of the optical system.

[0015] Fig.13 According to an embodiment of the present disclosure, the Fig.11A and Fig. 11B Correction optical unit Figure 1 Example overall shapes for asymmetric freeform surfaces of example optical elements of optical systems.

[0016] Fig.14A and Fig. 14B Yes, according to another example of the present disclosure, Figure 1 Schematic diagram of the correction optical unit of the optical system.

[0017] Fig.15A According to the embodiment of the present disclosure, in the Fig.14A and Fig. 14B Correction optical unit Figure 1 Surface sag of an example optical component surface in a direction perpendicular to the field of view of the optical system.

[0018] Fig. 15B According to the embodiment of the present disclosure, in the Fig.14Aand Fig. 14B Correction optical unit Figure 1 Surface sag of an example optical element surface in the horizontal field of view direction of the optical system.

[0019] Fig.16 According to an embodiment of the present disclosure, the Fig.14A and Fig. 14B Correction optical unit Figure 1 Example overall shapes of asymmetric freeform surfaces of example optical elements of optical systems.

[0020] Fig.17 According to the embodiment of the present disclosure, the distance includes Fig.14A and Fig. 14B Correction optical unit Figure 1 Deviation of the best-fit sphere from the surface of an example optical component of an optical system.

[0021] Fig.18 According to some embodiments of the present disclosure, relative to Figure 1 The stereoscopic depth of the horizontal field of view in an optical system.

[0022] Fig.19 According to some embodiments of the present disclosure, Figure 1 The size and position of three-dimensional virtual images within the horizontal field of view of several scenes in the field of view of the optical system.

[0023] Fig. 20 According to some embodiments of the present disclosure, Figure 1 The size and position of three-dimensional virtual images within the horizontal and vertical fields of view of several scenes in the field of view of the optical system.

[0024] Fig.21 It is shown that according to some embodiments of the present disclosure, for Figure 1 A graph of the combiner focal length for each of several virtual image distances of an optical system versus the volume of the optical system.

[0025] Fig. 22 Shown is the horizontal field of view of a side-view optical system according to an embodiment of the present disclosure.

[0026] Fig.23 Example stereo depth showing tilt angle relative to the virtual image surface.

[0027] Fig.24A -B Displays the Fig.23 Example scene of the tilt angle of the virtual image surface from the observer's 3D virtual image size and depth.

[0028] Fig.25 Example stereo depth showing field of view angle relative to the virtual image surface.

[0029] Fig.26A -B Displays the Fig.25 Example scene of the 3D virtual image size and depth of the virtual image surface in the field of view from the observer.

[0030] Fig. 27 Displays the vertical field of view limits relative to the combiner size. Summary of the invention

[0031] According to an example of the present disclosure, an optical system is compact and capable of producing augmented reality in a heads-up display with a relatively high stereoscopic depth of field, overcoming the limitation of the available size of virtual objects, which does not exceed the stereo threshold and is not perceived as tilted by an observer. In one example, the optical system includes an image generation unit, a correction optical unit, and a combiner. The correction optical unit is configured to produce a monotonic change in the optical path length of light propagating from the image generation unit in a horizontal field of view direction. The combiner is configured to redirect the light propagating from the correction optical unit toward an eye box, thereby producing one or more virtual images observable from the eye box. The optical system provides a virtual image surface tilted in the horizontal field of view direction for displaying one or more virtual images at different distances from an observer, such that a virtual image on a first side of the virtual image surface appears to be closer to the eye box than a virtual image on a second side of the virtual image surface. The virtual image surface has a non-zero angle between projections on a horizontal plane defined by a first axis and a second axis, the first axis being perpendicular to the virtual image surface and extending through any intersection on the virtual image surface, while the second axis being parallel to the line of sight and extending through any intersection on the virtual image surface. The technology provided by the present disclosure is particularly useful in the context of motor vehicles. Numerous configurations and variations and other example use cases will be known from the present disclosure. DETAILED DESCRIPTION

[0032] Overview

[0033] As previously described, some types of optical systems provide a head-up display using a combiner that combines light from an external (e.g., real-world) environment with an artificially generated image, including virtual objects or symbols projected into the viewer's field of view. Such a display is also referred to as an augmented reality head-up display (AR HUD). In order to provide a natural, fully integrated three-dimensional (stereoscopic) visual perception of virtual objects in the external environment, the AR HUD can be arranged so that the observer can perceive virtual objects at different distances along the virtual image surface, which provides a sense of depth of these objects in the augmented reality scene. As used herein, the term virtual image surface refers to an imaginary surface (planar or non-planar) on which virtual objects and other virtual images appear to be located when viewed from the eye box in the field of view. In general, the visual ergonomics of an AR HUD improves as the stereoscopic depth of field increases. For example, a large stereoscopic depth of field increases the number of virtual objects that can appear simultaneously at different distances in front of the observer.

[0034] Standard AR HUDs achieve stereoscopic depth of field by tilting the virtual image surface relative to the road or ground (tilt of the virtual image surface in the vertical field of view direction). In such AR HUDs, virtual objects displayed in the lower part of the field of view appear closer to the observer than virtual objects displayed in the upper part of the field of view. However, some existing AR HUDs have relatively small stereoscopic depth of field, for example due to structural limitations of the maximum size of the vertical field of view (FoV) of the HUD and the spatial orientation of the virtual image surface. The structural limitation of the maximum size of the vertical FoV of the HUD is related to the size of the combiner. In existing vehicle HUDs, the combiner tilt angle exceeds 60°, so the combiner size is at least twice larger than the projection of the combiner on the vertical plane. Therefore, the increase in the vertical field of view causes an increase in the size of the combiner, an increase in the numerical aperture, and thus a rapid increase in aberrations (especially an increase in astigmatism). These limitations, as well as the limitations of human binocular vision, also limit the maximum available size of virtual objects that are not perceived as tilted. For example, due to the limited size of the vertical field of view of the HUD, a virtual image surface tilted in the direction of the vertical field of view may provide a limited stereoscopic depth of field. When the virtual image is tilted in the direction of the vertical field of view, the stereoscopic depth of field may be increased by increasing the tilt angle of the virtual image surface. However, increasing the tilt angle relative to the direction of the vertical field of view may reduce the available size and / or height of virtual objects (which are not perceived as tilted) displayed on the virtual image surface tilted in the direction of the vertical field of view. This reduction in the available size of virtual objects may limit the improvement of stereoscopic depth of field in existing HUDs.

[0035] To this end, according to examples of the present disclosure, an optical system is provided that is relatively compact and capable of producing augmented reality in a heads-up display with a relatively high stereoscopic depth of field, overcoming the limitations of the available size of virtual objects (not perceived as tilted). An example optical system includes an image generation unit, a corrective optical unit, and a combiner. The corrective optical unit is configured to produce a monotonic variation in the optical path length of light propagating from the image generation unit in a horizontal field of view direction. The combiner is configured to redirect the light propagating from the corrective optical unit to an eyebox, thereby producing one or more virtual images observable at the eyebox.

[0036] Therefore, the optical system provides a virtual image surface tilted in the horizontal field of view direction for displaying one or more virtual images at different distances from the observer, so that one or more virtual images on a first side of the virtual image surface appear to be closer to the eye box than one or more virtual images on a second side of the virtual image surface. By tilting the virtual image surface in the horizontal field of view direction (horizontally tilted), the stereoscopic depth of field can be increased by at least two times compared to the prior art in which the virtual image surface is tilted in the vertical field of view direction (vertically tilted). This benefit means that the horizontal field of view of the existing AR HUD is always at least twice as wide as the vertical field of view.

[0037] To produce a tilted virtual image surface, in some examples, the corrective optical unit includes a specific combination of optical elements. For example, the tilt of the virtual image surface can be achieved by tilting the lens through which the optical image passes, by using an optical surface with an asymmetric shape, forming a wedge with an adjacent optical surface, or by using a combination of tilted lenses and asymmetric optical surfaces. In some examples, the combiner includes a holographic optical element with positive optical power, which in combination with the corrective optical unit can further increase the stereoscopic depth of field. Various other examples will be apparent in light of this disclosure.

[0038] Example Optical System

[0039] Figure 11 is a block diagram of an augmented reality display environment 100 according to an example of the present disclosure. The environment 100 includes a vehicle 102 having an optical system (such as a heads-up display or HUD) 104. The vehicle 102 can be any type of vehicle (e.g., a passenger vehicle, such as a car, truck, or limousine; a boat; an airplane). In some examples, at least a portion of the optical system 104 is mounted between (or inside) the windshield 102a and the driver in the passenger vehicle 102, while other examples may include such a second type of optical system 104 mounted between the side windows 102a and the passengers, as discussed below. The optical system 104 is configured to generate a virtual image 108 visible from an eye box 106 of the vehicle driver. The eye box 106 is an area or location in which the driver's single or double eye can see the virtual image 108, so that during operation of the vehicle 102, the driver's head occupies or is adjacent to at least a portion of the eye box 106. The virtual image 108 includes one or more virtual objects, symbols, characters, or other elements optically located in front of the vehicle 102, such that the virtual image 108 appears to be at a non-zero distance (to a perceived infinity) from the vehicle 102 (e.g., in front of the vehicle 102). When combined with light from the real-world environment (e.g., the area in front of the vehicle 102), such a virtual image 108 is also referred to as an augmented reality.

[0040] That is, as further described in detail below, the optical system 104 generates an inclined virtual image surface that is not perpendicular to the line of sight through the system 104, so that virtual objects on the left side of the virtual image 108 are displayed closer to the viewer than virtual objects on the right side of the virtual image 108, or virtual objects on the right side of the field of view of the system 104 are displayed closer to the viewer than virtual objects on the left side of the field of view of the system 104, depending on the tilt angle of the virtual image surface in the horizontal field of view direction. The line of sight is a line extending from the center of the eye box area 106 to the center of the field of view area of ​​the optical system 104. According to an embodiment of the present disclosure, the optical system 104 is designed to occupy a relatively small and compact area (in terms of volume) so that it can be easily integrated into the structure of the vehicle 102. Refer to the following text Figure 2 , Figure 4A -B. Fig.11A -B and Fig.14A -B describes multiple examples of the optical system 104.

[0041] Figure 2 According to the examples disclosed in this Figure 1 Schematic diagram of optical system 104. The optical system 104 can be implemented as Figure 1The optical system 104 includes a picture generating unit (PGU) 202, a correction optical unit 204, and a combiner 206. In some examples, the PGU 202 may include a digital micromirror device (DMD) projector, a liquid crystal on silicon (LCoS) projector, a liquid crystal display (LCD) with a laser-illuminated projector, a microelectromechanical system (MEMS) projector with a dual-axis scanning mirror or two single-axis scanning mirrors, a semiconductor laser array, a thin film transistor liquid crystal display (TFTLCD), an organic light emitting diode (OLED), an active matrix organic light emitting diode (AMOLED), or other suitable lighting devices. In some examples, the PGU 202 may also include a diffuser or a microlens array.

[0042] The PGU 206 is configured to generate and output an optical image 210, which is Figure 2 The optical image 210 may include, for example, one or more features (such as symbols, characters, or other elements) to be projected onto, or otherwise enhanced from, external light 214 from a real-world scene that is visible through the combiner 206. In some examples, the combiner 206 includes a holographic optical element (HOE) with positive optical power that may be placed on the interior surface of the windshield of the vehicle 102 or integrated into the windshield during a triplex manufacturing process.

[0043] The optical system 104 is arranged so that the optical image 210 output by the PGU 206 passes through the corrective optical unit 204, and the corrective optical unit 204 generates one or more modified optical images 212. The modified optical images 212 are redirected to the combiner 206 and then toward the eyebox 208 outside the optical system 104. The combiner 206 is also configured to allow at least some external light 214 to pass through the combiner 206 and combine with the redirected optical images to generate an augmented reality scene 216 visible from the window 208. In some examples, the augmented reality scene 216 includes Figure 1 An augmented reality display of a virtual image 108 , wherein at least some objects in the virtual image 108 are perceived by the driver or observer to be located on the virtual image surface but tilted horizontally relative to the field of view of the AR HUD optical system.

[0044] For example, Figure 3As shown, the combination of the PGU 202, the corrective optical unit 204, and the combiner 206 are arranged so that one or more virtual objects 302 displayed on the right side 304 of the field of view (the FoV of the horizontally tilted virtual image surface 310) 306 appear closer to the eyebox 208 than one or more virtual objects 308 displayed on the left side 312 of the FoV 306 of the horizontally tilted virtual image surface 310, wherein the right and left sides 304, 312 are defined relative to the horizontal FoV 306 from the eyebox 208. Figure 3 In , the horizontal plane (XZ) is defined relative to the local gravity direction, where the horizontal plane approximates the surface of the earth, or is defined relative to a vehicle, such as a motor vehicle, a ship, or an airplane. The stereo depth of field is defined as the distance range of the horizontally tilted virtual image surface 310 within the horizontal field of view 306. For example, the greater the tilt of the virtual image surface 310 in the horizontal field of view direction, the greater the stereo depth of field 314.

[0045] As mentioned above, the stereoscopic depth of field can be improved by increasing the tilt angle of the virtual image surface 310. However, increasing the tilt angle of the virtual image surface 310 will reduce the available size of the virtual object. Fig.23 As shown, at a vertical field of view of 6°, increasing the tilt angle of the virtual image surface from 79° to 85° can provide an increase in the stereo depth of field from 3.5 mrad to 6.6 mrad, or an increase in the number of scenes from five to nine. Fig.24A -B, the tilt angle is from 79°( Fig.24A ) to 85°( Fig. 24B ) would reduce the available size of virtual objects from 1.2° to 0.6°, respectively.

[0046] Another technique to improve stereo depth without affecting the usable size of virtual objects is to increase the field of view. Fig.25 As shown in FIG. 1 , while keeping the available size of the virtual object unchanged, doubling the field of view from 6° to 12° results in a doubling of the stereo depth from 5.8 m to 15.3 m, as shown in FIG. Fig.26A -B. However, AR HUD has a vertical field of view limitation. In existing automotive AR HUDs, the combiner tilt angle is greater than 60°, so the combiner size is at least twice larger than the projection of the combiner on the vertical plane, as shown in Figure 1. Fig. 27As shown. This will result in an increase in the size of the combiner, the numerical aperture, and the increase in aberrations (such as an increase in astigmatism), while at the same time increasing the vertical field of view. In addition, in the case of a holographic combiner, the diffraction efficiency distribution in the horizontal field of view direction is wider than the diffraction efficiency distribution in the vertical field of view direction. Therefore, the horizontal field of view of existing automotive ARHUDs is at least twice as large as the vertical field of view. Compared with existing designs, increasing the inclination of the virtual image surface in the horizontal field of view direction can provide a significant improvement in stereo depth of field, while keeping the available size of the virtual object unchanged, such as Fig.26A As shown in Figure 2-B, as the field of view size increases, the usable size can be maintained at 1.2°.

[0047] As previously described, according to embodiments of the present disclosure, the virtual image surface 310 is an imaginary surface on which virtual objects projected from the PGU 202 appear to be located. It will be appreciated that the virtual image surface 310 may be tilted, such as Figure 3 As shown, one or more virtual objects 302 displayed on the right side 304 of the field of view (FoV) 306 appear closer to the eye box 208 than one or more virtual objects 308 displayed on the left side 312 of the FoV 306, or the virtual image surface 310 can be tilted so that one or more virtual objects 302 displayed on the left side 312 of the field of view (FoV) 306 appear closer to the eye box 208 than one or more virtual objects 308 displayed on the right side 304 of the FoV 306.

[0048] First Example Corrective Optical Unit of AR Optical System

[0049] Figure 4A and 4B is a schematic diagram of a correction optical unit 400 according to an example of the present disclosure. The correction optical unit 400 can be implemented as Figure 2 At least a portion of the correction optical unit 204. The correction optical unit 400 includes a telecentric lens 402, an optical element 404 having a cylindrical surface and a non-spherical surface, a cylindrical reflector 406, and an output lens 408 having a non-spherical surface and a spherical surface. A telecentric lens is a compound lens with an entrance pupil or an exit pupil located at infinity, wherein the chief ray is parallel or substantially parallel to the local optical axis in front of or behind the lens, respectively. The optical element 404 is tilted at an angle β relative to the local optical axis 410 in a direction 412 of the horizontal FoV. For example, the optical element 404 can be tilted at an angle β toward a first side of the horizontal FoV, such as Figure 4B As shown, or tilted toward a second side of the horizontal FoV. In some examples, the diffuser 414 can be incorporated as part of the correction optical unit 400 or PGU 202.

[0050] In some examples, the optical system 104 operates in a monochromatic mode at a wavelength of 532 nm. Figure 2 , 4A 4B, the operation of the optical system 104 with the corrective optical unit 400 is as follows. The PGU 202 projects the optical image 210 onto the diffuser 414. Light from the diffuser 414 propagates through the corrective optical unit 400, wherein the tilted optical element 404 (e.g., tilted relative to the local coordinate axes FoVx, FoVy,z) produces a monotonic variation in the optical path length in the direction of the horizontal field of view 412, thereby producing a modified optical image 212. The modified optical image 212 light reaches the combiner 206, which redirects the modified optical image 212 to the eyebox 208. The optical path length varies monotonically at a non-zero angle α to form a tilted virtual image surface, such as Figure 5 As shown, this angle is between the projection of a perpendicular line through any point on the virtual image surface onto the horizontal plane (defined as the XZ plane) and the projection of the line of sight onto the horizontal plane.

[0051] Figure 6 According to an example of the present disclosure, a local coordinate system (FoVx, FoVy, Z) and Figure 1 The components of the optical system 104, including the PGU 202, the corrective optics unit 204, and the combiner 206, are transformed in spatial relationship. The direction in which the corrective optics unit 400 produces a monotonic change in the optical path length is related to the local coordinate system (FoVx, FoVy, Z) used to define the FoV, where the Z axis coincides with the local optical axis defined as the chief ray passing through the center of the field of view region (FoVx, FoVy).

[0052] Now refer to Figure 7 , the stereo depth of the optical system 104 is estimated as follows. The stereo depth of view in linear measurement is the difference between the point Lnear closest to the observer and the point Lfar farthest from the observer:

[0053] Δd=L far -L near

[0054] Stereoscopic depth measured in degrees is the angle η in milliradians (mrad), defined as the difference between the angles ω and θ at the points closest to the observer and farthest from the observer.

[0055] η=ω-θ

[0056] The stereoscopic depth can be estimated in a plurality of scenes (e.g., scene 1, scene 2, etc.) of a 3D virtual image located between a point closest to a viewer and a point farthest from the viewer. The size of each scene in the 3D virtual image is an area at a predetermined distance from the viewer in which a virtual object (e.g., Figure 7 The letters "A" and "B" in the figure are not perceived as tilted. The size of each scene is defined by the available size of the virtual object (not perceived as tilted), the field of view, and the viewing distance L. Dividing the virtual image surface into multiple scenes can show the available size of the virtual object at a predetermined distance, the aspect ratio of the virtual object, and the position of the virtual object in the field of view.

[0057] The available size of virtual objects (without being perceived as tilted) is limited by the stereoscopic threshold of human vision, e.g. Figure 8 The stereo threshold is the minimum stereo depth that an observer can reliably discern and is based on the physiological properties of human vision. For example, the stereo threshold may be approximately 150 arc seconds. The greater the tilt angle of the virtual image surface, the smaller the available size of the virtual object that the observer will not perceive as tilted.

[0058] Fig.9A and Fig. 9B According to an embodiment of the present disclosure, the 532 nm operating wavelength is used to contain Figure 4A and Figure 4B Example design parameters of the optical system 104 of the correction optical unit 400.

[0059] Fig. 10A and 10B 2 shows example HOE recording parameters for a combiner 206 of an optical system 104 having a Figure 4A and 4B The corrected optical unit 400 is used for an operating wavelength of 532 nanometers. Fig. 10B Lists example Zernike fringe coefficients for the HOE combiner.

[0060] Second Example Correction Optical Unit of AR Optical System

[0061] Fig.11A and 11B According to another example of the present disclosure, a schematic diagram of a correction optical unit 1100 is shown. The correction optical unit 1100 may be implemented as Figure 2At least a portion of the corrective optical unit 204. The corrective optical unit 1100 includes a telecentric lens 1102, an optical element 1104 having a cylindrical surface and an aspherical surface, a free-form mirror 1106 (a mirror having a free-form surface profile), and an output lens 1108 having an aspherical surface and a spherical surface. The optical element 1104 is tilted at an angle β relative to the local optical axis 1110 in the direction of the horizontal field of view 1112. In some examples, a diffuser 1114 can be included as part of the corrective optical unit 1100 or the PGU 202.

[0062] The free-form mirror 1106 has an asymmetric surface profile formed by a wedge shape with the adjacent optical surfaces of the optical element 1104 and the output lens 1108. In some examples, the cross-sectional shape of the free-form mirror 1106 in the direction perpendicular to the field of view can be close to a parabolic cylindrical surface, such as Fig. 12A In some examples, the cross-sectional shape of the free-form mirror 1106 in the horizontal field of view direction may have an asymmetric profile with a maximum droop of about 60 micrometers (μm), as shown in FIG. Fig. 12B shown. Fig.13 An example of the overall shape of the free-form mirror 1106 surface is shown.

[0063] Now refer to Figure 2 , 11A 11B, the operation of the optical system 104 with the corrective optical unit 1100 is as follows. The PGU 202 projects the optical image 210 onto the diffuser 1114. Light from the diffuser 1114 propagates through the corrective optical unit 1100, wherein the tilted optical element 1104 and the free-form mirror 1106 produce a monotonic variation in the optical path length in the direction of the horizontal field of view 1112, thereby producing a modified optical image 212. The modified optical image 212 arrives at the combiner 206, which redirects the modified optical image 212 to the eyebox 208. The optical path length varies monotonically at a non-zero angle α to form a tilted virtual image surface, such as Figure 5 As shown, this angle is between the projection of a perpendicular line through any point on the virtual image surface onto the horizontal plane (defined as the XZ plane) and the projection of the line of sight onto the horizontal plane.

[0064] Third Example Correction Optical Unit of AR Optical System

[0065] Fig.14A and 14B According to yet another example of the present disclosure, a schematic diagram of a correction optical unit 1400 is shown. The correction optical unit 1400 may be implemented as Figure 2At least a portion of the corrective optical unit 204. The corrective optical unit 1400 includes a telecentric lens 1402, an optical element 1404 having a cylindrical surface and an aspherical surface, a cylindrical mirror 1406, and an output lens 1408 having a freeform surface and a spherical surface. The optical element 1404 is tilted at an angle β relative to the local optical axis 1410 in the direction of the horizontal field of view 1412. In some examples, a diffuser 1414 can be included as part of the corrective optical unit 1400 or PGU 202.

[0066] The free-form surface of the output lens 1408 in the light propagation direction has an asymmetric free-form profile and forms a wedge shape with the adjacent optical surfaces of the output lens 1408 and the reflection mirror 1406 in the horizontal field of view direction. In some examples, the cross-sectional shape of the free-form surface of the output lens 1408 in the vertical field of view direction may have a symmetrical shape close to a sphere with a radius of about -280 mm, such as Fig.15A In some examples, the cross-sectional shape of the free-form surface of the output lens 508 in the horizontal field of view direction may have an asymmetric shape close to a sphere with a radius of about -400 mm, such as Fig. 15B shown. Fig.16 An example overall shape of the free-form surface of the output lens 1408 is shown, which resembles a biconical surface. The best-fit sphere of the first surface of the output lens 1408 can be calculated as the sphere that minimizes the sum of squared residuals. The maximum deviation of the free-form surface of the output lens 1408 from the best-fit sphere with a radius of -426.6 millimeters (mm) is approximately 4 mm, i.e., Fig.17 shown.

[0067] Now refer to Figure 2 , 14A 14B, the operation of the optical system 104 with the corrective optical unit 1400 is as follows. The PGU 202 projects the intermediate image onto the diffuser 1414. Light from the diffuser 1414 propagates through the corrective optical unit, wherein the tilted optical element 1404 and the output lens 1408 with a free-form surface produce a monotonic variation of the optical path length in the direction of the horizontal field of view 1412, resulting in a modified optical image 212. The modified optical image 212 reaches the combiner 206, which redirects the modified optical image 212 to the eyebox 208. The optical path length varies monotonically at a non-zero angle α to form a tilted virtual image surface, as shown in FIG. Figure 5 As shown, this angle is between the projection of a perpendicular line through any point on the virtual image surface onto the horizontal plane (defined as the XZ plane) and the projection of the line of sight onto the horizontal plane.

[0068] Further Examples

[0069] In some examples, the optical system 104 can operate in a monochrome mode or in a full color mode with chromatic aberration correction.

[0070] Table 1 shows example geometric characteristics of optical system 104 .

[0071]

[0072] Table 1

[0073] Fig.18 1800 of the optical system 104 according to an example of the present disclosure. In this example, virtual objects on the right side of the field of view 1800 are displayed as being closer to the viewer than virtual objects on the left side of the field of view 1800. The angle between the projection of a perpendicular line to any point on the virtual image surface on the horizontal plane and the projection of the line of sight on the horizontal plane is 72°, which corresponds to a stereo depth of field of view of 4.84 milliradians, and virtual objects with a usable size and / or width of 2° (which are not perceived as tilted) and seven (7) scenes in the three-dimensional virtual image, such as shown in Tables 2 and 3. Fig.19 Those listed. Fig. 20 Scenes within the field of view defined in a plurality of regions at a predetermined distance from the viewer are displayed, wherein the displayed virtual objects are not perceived as tilted. The size of each scene is limited by the available size of the virtual objects and the vertical field of view FoV (V).

[0074] Table 2 shows the stereoscopic depth of field parameters of the optical system 104 according to an example of the present disclosure, wherein the available sizes of virtual objects are listed for a stereoscopic threshold value of 150 arc seconds.

[0075] Virtual image surface tilt angle α, degrees 72 Linear stereo depth of field Δd, m 8,8 Angular stereo depth of field η, mrad 4,84 Number of scenes 7 Available size of virtual objects*, degrees 2

[0076] Table 2

[0077] In some examples, to achieve greater stereo depth of field, the combiner 206 includes a HOE. One advantage of a holographic combiner in an AR HUD optical system is that it can provide a wide field of view while maintaining the compactness of the AR HUD. For example, Fig.21 The correlation between the combiner focal length, AR HUD volume, and virtual image distance is shown for a distance from the eyebox to the combiner of approximately 700 mm, a circular eyebox radius of 71 mm, and a field of view radius of 6.5 degrees. Fig.21As shown, the smaller the focal length of the combiner (or the higher the optical magnification of the combiner), the smaller the volume of the AR HUD required to create a virtual image at a distance of more than 3m from the viewer. A combiner with a low optical magnification can, for example, be incorporated into a windshield reflection area and have a focal length greater than about 1000mm. Conversely, in some examples, a holographic combiner such as combiner 206 of optical system 104 can have a small focal length (a high optical magnification of about 1.1-6.6 diopters). Therefore, for the same AR HUD volume, an AR HUD with a holographic combiner provides a wider field of view than an AR HUD with a combiner with a low optical magnification. The result of the holographic combiner is an increased field of view and stereo depth of field.

[0078] Another advantage according to some examples of the present disclosure is that the optical system 104 is suitable for integration into a side-view AR HUD, where the observer observes the real world around the vehicle 102 at an angle to the direction of travel, such as Fig. 22 For example, when the vehicle 102 is moving, a passenger sitting near the side window is observing the surrounding real world at a certain angle γ relative to the direction of travel, and the passenger's eyes naturally follow the objects 2200 located along the road. To align the perspective of the virtual objects observed by the viewer in the side-view AR HUD with the direction of travel and place the virtual objects along the road, the angle α (between the projection of the vertical line of any point on the virtual image surface on the horizontal plane and the projection of the line of sight on the horizontal plane) can be matched according to the angle γ between the line of sight and the direction of travel.

[0079] Further exemplary embodiments

[0080] The following examples describe further exemplary embodiments, from which many arrangements and configurations will become apparent.

[0081] Example 1 provides an optical system for an augmented reality head-up display. The optical system includes an image generating unit; a corrective optical unit configured to generate a monotonic change in the optical path length of light propagated from the image generating unit in a horizontal field of view direction; and a combiner configured to redirect the light propagated from the corrective optical unit to an eye box, thereby generating one or more virtual images observable from the eye box; wherein the optical system provides a virtual image surface tilted along the horizontal field of view direction for displaying one or more virtual images at different distances from the eye box, the virtual image surface having a non-zero angle between projections on a horizontal plane defined by a first axis and a second axis, the first axis being perpendicular to the virtual image surface and extending through any intersection on the virtual image surface, and the second axis being parallel to the line of sight and extending through any intersection on the virtual image surface, so that virtual images on a first side of the virtual image surface appear to be closer to the eye box than virtual images on a second side of the virtual image surface.

[0082] Example 2 includes the subject matter of Example 1, wherein the correction optical unit includes at least one optical element having at least one optical surface inclined in the direction of the horizontal field of view.

[0083] Example 3 includes the subject matter of any of Examples 1 and 2, wherein the corrective optical unit includes at least one optical element including at least one optical surface having an asymmetric cross-sectional profile.

[0084] Example 4 includes the subject matter of Example 1, wherein the corrective optical unit comprises a combination of at least one optical element tilted along a horizontal field of view direction and at least one optical surface having an asymmetric cross-sectional profile.

[0085] Example 5 includes the subject matter of any of Examples 1-4, wherein the combiner includes a holographic optical element having positive optical power.

[0086] Example 6 includes the subject matter of any one of Examples 1-5, wherein the correction optical unit includes a telecentric lens located between the image generating unit and the optical element, the optical element including a lens having a cylindrical surface and a non-spherical surface; a reflection mirror located between the optical element and the combiner, the reflection mirror including a cylindrical surface; and an output lens located between the reflection mirror and the combiner, the output lens including a first surface and a second surface, the first surface having a non-spherical cross-sectional profile, and the second surface having a spherical cross-sectional profile.

[0087] Example 7 includes the subject item of any one of Examples 1-5, wherein the correction optical unit includes a telecentric lens, which is located between the image generating unit and the optical element, and the element includes a lens having a cylindrical surface and an aspherical surface; a reflection mirror, which is located between the optical element and the combiner, and the reflection mirror includes at least one optical surface, and the at least one optical surface has a free shape with an asymmetric cross-sectional profile; and an output lens, which is located between the reflection mirror and the combiner, and the output lens includes a first surface and a second surface, the first surface has a aspherical cross-sectional profile, and the second surface has a spherical cross-sectional profile.

[0088] Example 8 includes the subject matter of any one of Examples 1-5, wherein the correction optical unit includes a telecentric lens located between the image generating unit and the optical element, the element including a lens having a cylindrical surface and an aspherical surface; a reflection mirror located between the optical element and the combiner, the reflection mirror including a cylindrical surface; and an output lens located between the reflection mirror and the combiner, the output lens including a first surface and a second surface, the first surface including a free shape having an asymmetric cross-sectional profile in a horizontal field of view direction, and the second surface having a spherical cross-sectional profile.

[0089] Example 9 includes the subject matter of any one of Examples 1-8, wherein the inclined virtual image surface is approximately a plane.

[0090] Example 10 includes the subject matter of any one of Examples 1-9, wherein the correction optical unit is implemented for a side view perception function and provides an inclined virtual image surface aligned with the travel direction of the vehicle.

[0091] Example 11 provides an optical system for an augmented reality head-up display. The optical system includes an image generation unit for generating an optical image; a correction optical unit configured to create a monotonic change in a plurality of optical path lengths of light rays in an optical image propagated from the image generation unit in a horizontal field of view direction, thereby generating a plurality of modified optical images; and a combiner configured to redirect the modified optical image propagated from the correction optical unit to an eye box, thereby generating one or more virtual images observable from the eye box; wherein the optical system provides a virtual image surface tilted along the horizontal field of view direction for displaying one or more virtual images at different distances from the eye box, the virtual image surface having a non-zero angle between projections on a horizontal plane defined by a first axis and a second axis, the first axis being perpendicular to the virtual image surface and extending through any intersection on the virtual image surface, the second axis being parallel to the line of sight and extending through any intersection on the virtual image surface, so that virtual images on a first side of the virtual image surface appear to be closer to the eye box than virtual images on a second side of the virtual image surface.

[0092] Example 12 includes the subject matter of Example 11, wherein the correction optical unit includes at least one optical element having at least one optical surface tilted in the direction of the horizontal field of view.

[0093] Example 13 includes the subject matter of any of Examples 11 and 12, wherein the corrective optical unit includes at least one optical element including at least one optical surface having an asymmetric cross-sectional profile.

[0094] Example 14 includes the subject matter of Example 11, wherein the corrective optical unit comprises a combination of at least one optical element tilted along a horizontal field of view direction and at least one optical surface having an asymmetric cross-sectional profile.

[0095] Example 15 includes the subject matter of any of Examples 11-14, wherein the combiner includes a holographic optical element having positive optical power.

[0096] Example 16 includes the subject matter of any one of Examples 11-15, wherein the correction optical unit includes a telecentric lens located between the image generating unit and the optical element, the optical element including a lens having a cylindrical surface and a non-spherical surface; a reflection mirror located between the optical element and the combiner, the reflection mirror including a cylindrical surface; and an output lens located between the reflection mirror and the combiner, the output lens including a first surface and a second surface, the first surface having a non-spherical cross-sectional profile, and the second surface having a spherical cross-sectional profile.

[0097] Example 17 includes the subject item of any one of Examples 11-15, wherein the correction optical unit includes a telecentric lens, which is located between the image generating unit and the optical element, and the element includes a lens having a cylindrical surface and an aspherical surface; a reflection mirror, which is located between the optical element and the combiner, and the reflection mirror includes at least one optical surface, and the at least one optical surface has a free shape with an asymmetric cross-sectional profile; and an output lens, which is located between the reflection mirror and the combiner, and the output lens includes a first surface and a second surface, the first surface has a aspherical cross-sectional profile, and the second surface has a spherical cross-sectional profile.

[0098] Example 18 includes the subject matter of any one of Examples 11-15, wherein the correction optical unit includes a telecentric lens located between the image generating unit and the optical element, the element including a lens having a cylindrical surface and an aspherical surface; a reflection mirror located between the optical element and the combiner, the reflection mirror including a cylindrical surface; and an output lens located between the reflection mirror and the combiner, the output lens including a first surface and a second surface, the first surface including a free shape having an asymmetric cross-sectional profile in a horizontal field of view direction, and the second surface having a spherical cross-sectional profile.

[0099] Example 19 includes the subject matter of any one of Examples 11-18, wherein the tilted virtual image surface is approximately a plane.

[0100] Example 20 includes the subject matter of any one of Examples 11-19, wherein the correction optical unit is implemented as a side view perception function and provides an inclined virtual image surface aligned with the travel direction of the vehicle.

[0101] The foregoing description and drawings of various embodiments are presented by way of example only. These examples are not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. According to the present disclosure, substitutions, modifications and changes are obvious and are intended to fall within the scope of the present disclosure as described in the scope of the patent application. In addition, the wording and terminology used in this case are for descriptive purposes and should not be considered as limiting. Any singular reference to the examples, components, elements or actions of the systems and methods referenced in this case may also include examples containing plural numbers, and any plural reference to any examples, components, elements or actions in this case may also include examples containing only singular numbers. References in singular or plural form are not intended to limit the systems or methods, their components, actions or elements of the present disclosure. The present disclosure uses the words "comprise", "contain", "have" or "have" or "involve" and their variants to indicate that the items listed below and their equivalents and additional items are covered. References to "or" may be interpreted as inclusive, so that any term described using "or" may indicate any one, more than one, or all of the terms described. In addition, if there is an inconsistency in the usage of terms between this document and documents incorporated by reference, the usage of terms in the incorporated references is supplemental to the usage of terms in this document; for irreconcilable inconsistencies, the usage of terms in this document shall prevail.

Claims

1. An optical system for an augmented reality head-up display, the optical system comprising: an image generating unit; a corrective optical unit configured to produce a monotonic variation in the optical path length of light rays propagating from the image generating unit in a horizontal field of view direction; and a combiner configured to redirect light propagating through the corrective optical unit to the eyebox to generate one or more virtual images observable from the eyebox; in, The optical system provides a virtual image surface tilted along a horizontal field of view direction for displaying one or more virtual images at different distances from an eye box, the virtual image surface having a non-zero angle between projections on a horizontal plane defined by a first axis and a second axis, the first axis being perpendicular to the virtual image surface and extending through any intersection on the virtual image surface, and the second axis being parallel to the line of sight and extending through any intersection on the virtual image surface, so that the virtual image on a first side of the virtual image surface appears closer to the eye box than the virtual image on a second side of the virtual image surface. 2 . The optical system according to claim 1 , wherein the correction optical unit comprises at least one optical element having at least one optical surface inclined in the horizontal field of view direction.

3. The optical system of claim 1, wherein the correction optical unit comprises at least one optical element having at least one optical surface with an asymmetric cross-sectional profile.

4. The optical system according to claim 1, wherein the correction optical unit comprises a combination of at least one optical element tilted in the horizontal field of view direction and at least one optical surface having an asymmetric cross-sectional profile.

5. The optical system of claim 1, wherein the combiner comprises a holographic optical element having positive optical power.

6. The optical system according to claim 5, wherein the correction optical unit comprises: a telecentric lens located between the image generating unit and the optical element, the optical element comprising a lens having a cylindrical surface and an aspherical surface; a mirror located between the optical element and the combiner, the mirror comprising a cylindrical surface; and An output lens is located between the reflection mirror and the combiner, and includes a first surface and a second surface. The first surface has a non-spherical surface cross-sectional profile, and the second surface has a spherical cross-sectional profile.

7. The optical system according to claim 5, wherein the correction optical unit comprises: a telecentric lens located between the image generating unit and the optical element, the optical element comprising a lens having a cylindrical surface and an aspherical surface; a mirror located between the optical element and the combiner, the mirror comprising at least one optical surface having a free-form shape with an asymmetric cross-sectional profile; and An output lens is located between the reflection mirror and the combiner, and includes a first surface and a second surface. The first surface has a non-spherical surface cross-sectional profile, and the second surface has a spherical cross-sectional profile.

8. The optical system according to claim 5, wherein the correction optical unit comprises: a telecentric lens located between the image generating unit and the optical element, the optical element comprising a lens having a cylindrical surface and an aspherical surface; a mirror located between the optical element and the combiner, the mirror comprising a cylindrical surface; and An output lens is located between the reflector and the combiner, the output lens comprising a first surface and a second surface, the first surface having a free shape with an asymmetric cross-sectional profile in a horizontal field of view direction, and the second surface having a spherical cross-sectional profile.

9. The optical system according to claim 1, wherein the inclined virtual image surface is approximately a plane.

10. The optical system according to claim 1, wherein the correction optical unit is implemented as a side view sensing function and provides an inclined virtual image surface aligned with the traveling direction of the vehicle.

11. An optical system for an augmented reality head-up display, the optical system comprising: an image generating unit for generating an optical image; a corrective optical unit configured to create a monotonic variation of a plurality of optical path lengths of light rays of the optical image propagating from the image generating unit in a horizontal field of view direction, thereby generating a plurality of modified optical images; and a combiner configured to redirect the modified optical image propagating from the corrective optical unit to the eyebox, thereby generating one or more virtual images observable from the eyebox; in, The optical system provides a virtual image surface tilted along a horizontal field of view direction for displaying one or more virtual images at different distances from an eye box, the virtual image surface having a non-zero angle between projections on a horizontal plane defined by a first axis and a second axis, the first axis being perpendicular to the virtual image surface and extending through any intersection on the virtual image surface, and the second axis being parallel to the line of sight and extending through any intersection on the virtual image surface, so that the virtual image on a first side of the virtual image surface appears closer to the eye box than the virtual image on a second side of the virtual image surface. 12 . The optical system according to claim 11 , wherein the correction optical unit comprises at least one optical element having at least one optical surface inclined in the horizontal field of view direction.

13. The optical system of claim 11, wherein the corrective optical unit comprises at least one optical element having at least one optical surface with an asymmetric cross-sectional profile.

14. The optical system of claim 11, wherein the correction optical unit comprises a combination of at least one optical element tilted in the horizontal field of view direction and at least one optical surface having an asymmetric cross-sectional profile.

15. The optical system of claim 11, wherein the combiner comprises a holographic optical element having positive optical power.

16. The optical system according to claim 15, wherein the correction optical unit comprises: a telecentric lens located between the image generating unit and the optical element, the optical element comprising a lens having a cylindrical surface and an aspherical surface; a mirror located between the optical element and the combiner, the mirror comprising a cylindrical surface; and An output lens is located between the reflection mirror and the combiner, and includes a first surface and a second surface. The first surface has a non-spherical surface cross-sectional profile, and the second surface has a spherical cross-sectional profile.

17. The optical system according to claim 15, wherein the correction optical unit comprises: a telecentric lens located between the image generating unit and the optical element, the optical element comprising a lens having a cylindrical surface and an aspherical surface; a mirror located between the optical element and the combiner, the mirror comprising at least one optical surface having a free-form shape with an asymmetric cross-sectional profile; and An output lens is located between the reflection mirror and the combiner, and includes a first surface and a second surface. The first surface has a non-spherical surface cross-sectional profile, and the second surface has a spherical cross-sectional profile.

18. The optical system according to claim 15, wherein the correction optical unit comprises: a telecentric lens located between the image generating unit and the optical element, the optical element comprising a lens having a cylindrical surface and an aspherical surface; a mirror located between the optical element and the combiner, the mirror comprising a cylindrical surface; and An output lens is located between the reflector and the combiner, the output lens comprising a first surface and a second surface, the first surface having a free shape with an asymmetric cross-sectional profile in a horizontal field of view direction, and the second surface having a spherical cross-sectional profile.

19. The optical system of claim 11, wherein the tilted virtual image surface is approximately a plane.

20. The optical system of claim 11, wherein the correction optical unit is implemented as a side view sensing function and provides an inclined virtual image surface aligned with the traveling direction of the vehicle.

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