First lens, lens system, and optical system

Abstract

Aspects of this disclosure provide a first lens. The first lens may include an optically transparent member having a first surface and a second surface. The optically transparent member may be configured to receive light from a display device through the first surface. The received light exits the optically transparent member through the second surface. The first and second surfaces of the optically transparent member may be aspherical. The inner surface of the first surface is convex, and the outer surface of the first surface is concave. The inner surface is surrounded by the outer surface of the first surface. The thickness of the central region of the first lens may decrease from the center of the first lens, and the thickness of the peripheral region of the first lens may increase from the boundary of the central region.

Description

[Technical Field]

[0001] Reference This application claims priority to U.S. Patent Application No. 18 / 136,258, “CATADIOPTRIC LENS FOR NEAR EYE DISPLAY,” filed on 18 April 2023, which is incorporated herein by reference in its entirety.

[0002] This disclosure generally describes embodiments relating to near-eye display technology. [Background technology]

[0003] The background art provided herein is intended to provide a general overview of the background of this disclosure. Research by the named inventors of the present invention, to the extent described in this background art section, and aspects of this specification that do not constitute prior art at the time of filing, are not considered prior art to this disclosure, either expressly or implicitly.

[0004] Near-eye displays (NEDs) are being developed to provide superior user experiences in fields such as augmented reality (AR) and virtual reality (VR). NEDs can include a variety of wearable devices, such as head-mounted display (HMD) devices and smart glasses. For example, an HMD device includes a relatively small display device and an optical system that can generate a virtual image within the field of view of one or both eyes. To the eye, the virtual image appears distant and much larger than the relatively small display device. [Overview of the project] [Means for solving the problem]

[0005] Aspects of this disclosure provide a first lens. The first lens may include an optically transparent member having a first surface and a second surface. The optically transparent member may be configured to receive light from a display device through the first surface. The received light exits the optically transparent member through the second surface. The first and second surfaces of the optically transparent member may be aspherical. The inner surface of the first surface is convex, and the outer surface of the first surface is concave. The inner surface is surrounded by the outer surface of the first surface.

[0006] In one embodiment, the curve formed by the intersection of the first surface of the first lens and the cross-sectional plane has at least four inflection points. The cross-sectional plane is parallel to the optical axis of the first lens.

[0007] In one embodiment, a plane perpendicular to the optical axis of the first lens intersects the second surface of the first lens four times.

[0008] In one example, the sagittal difference between (i) the minimum sagittal at a first position on the first surface of the first lens and (ii) the maximum sagittal at a second position on the first surface of the first lens is between 1.5 millimeters (mm) and 2.5 mm.

[0009] In one example, the sagittal difference between (i) the minimum sagittal at a first position on the second surface of the first lens and (ii) the maximum sagittal at a second position on the second surface of the first lens is between 0.6 mm and 0.8 mm.

[0010] In one embodiment, the lens system includes a first lens and a second lens configured to guide light from a display device to the first lens. The first lens is located between the second lens and a light-receiving section. The second lens is a condensing lens.

[0011] In one example, the first lens and the second lens are separated by a gap.

[0012] In one embodiment, the optical system includes a lens system, a beam splitter configured to partially transmit and partially reflect a light beam from a display device, a reflective polarizer configured to transmit light in a first linearly polarized state and reflect light in a second linearly polarized state perpendicular to the first linearly polarized state, and a quarter-wave plate (QWP) positioned between the beam splitter and the reflective polarizer. The optical axes of the first lens and the second lens are identical in the lens system, the beam splitter is on a first surface of the second lens configured to face the display device, and the reflective polarizer is on a second surface of the first lens.

[0013] In one example, the QWP is located on the surface of (i) the first lens or (ii) the second lens.

[0014] In one example, the optical system includes a display device. A pixel array in the display device is configured to generate a light beam. The polarization state of the light beam is a first circularly polarized state. An optical resonator is formed between a beam splitter and a reflective polarizer. The optical resonator includes a first lens, a second lens, a gap between the first and second lenses, and a QWP (Quick Wave Pointer). The beam splitter partially transmits one of the light beams. After one of the light beams has passed through the optical resonator for the first time, the first circularly polarized state of one of the light beams is converted to a second linearly polarized state by the QWP. The reflective polarizer reflects one of the light beams in the second linearly polarized state. After one of the light beams has passed through the optical resonator for the second time, one of the light beams is reflected by the beam splitter. After one of the light beams has passed through the optical resonator for the third time, the second linearly polarized state of one of the light beams is converted back to the first linearly polarized state by the QWP, and the reflective polarizer transmits one of the light beams in the first linearly polarized state so that one of the light beams is directed towards the light receiver.

[0015] In one example, the optical system is included in a head-mounted display (HMD). The field of view of the optical system is 90° or more, the distance between the light receiving part and the first lens is 15 ± 2 millimeters (mm), the lens track length, which is the distance between the second lens and the display device, is from 12 to 21 mm, and the diagonal size of the area in the display device that generates the light beam is from 1.4 inches to 2.6 inches.

[0016] In one embodiment, the thickness of the central region of the first lens decreases from the center of the first lens, and the thickness of the peripheral region of the first lens increases from the boundary of the central region.

[0017] Further features, properties, and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings.

Brief Description of the Drawings

[0018] [Figure 1A] FIG. 1A shows a display system according to some embodiments of the present disclosure in a side view. [Figure 1B] FIG. 1B shows the first lens of a display system according to some embodiments of the present disclosure in a side view. [Figure 1C] FIG. 1C shows the first lens of a display system according to some embodiments of the present disclosure in a side view. [Figure 1D] FIG. 1D shows the lens system of a display system according to some embodiments of the present disclosure in a side view. [Figure 2] FIG. 2 shows examples of eye rotation and head rotation. [Figure 3] FIG. 3 shows the relationship between visual acuity and eccentricity. [Figure 4] FIG. 4 shows the relationship between the sag of the second surface of the first lens and the position along the axis perpendicular to the optical axis of the first lens. [Figure 5] FIG. 5 shows the relationship between the sag of the first surface of the first lens and the position along the axis perpendicular to the optical axis of the first lens. [Figure 6] Figure 6 shows the modulation transfer function (MTF) of the optical system using the first lens. [Figure 7] Figure 7 shows the modulation transfer function (MTF) of the optical system using the first lens. [Figure 8] Figure 8 shows the modulation transfer function (MTF) of the optical system using the first lens. [Figure 9] Figure 9 shows the modulation transfer function (MTF) of the optical system using the first lens. [Figure 10] Figure 10 shows the relative illuminance with respect to the viewing angle from 0° to 55°. [Figure 11A] Figure 11A shows an example of a display system including an optical system according to an embodiment of the present disclosure. [Figure 11B] Figure 11B shows an example of a display system including an optical system according to an embodiment of the present disclosure. [Figure 12] Figure 12 shows the relationship between the sag of the second surface of the first lens and the position along the axis perpendicular to the optical axis of the first lens according to an embodiment of the present disclosure. [Figure 13] Figure 13 shows the relationship between the sag of the first surface of the first lens and the position along the axis perpendicular to the optical axis of the first lens. [Figure 14] Figure 14 shows the MTF of the optical system using the first lens according to an embodiment of the present disclosure. [Figure 15] Figure 15 shows the MTF of the optical system using the first lens according to an embodiment of the present disclosure. [Figure 16] Figure 16 shows the MTF of the optical system using the first lens according to an embodiment of the present disclosure. [Figure 17] Figure 17 shows the MTF of the optical system using the first lens according to an embodiment of the present disclosure. [Figure 18] Figure 18 shows the relative illuminance with respect to the viewing angle from 0° to 50°. [Figure 19]Figure 19 shows exemplary shapes of the first and / or second surfaces of the first lens according to embodiments of the present disclosure. [Figure 20] Figure 20 shows exemplary shapes of the first and / or second surfaces of the first lens according to embodiments of the present disclosure. [Figure 21] Figure 21 shows exemplary shapes of the first and / or second surfaces of the first lens according to embodiments of the present disclosure. [Figure 22] Figure 22 shows exemplary shapes of the first and / or second surfaces of the first lens according to embodiments of the present disclosure. [Figure 23] Figure 23 shows exemplary shapes of the first and / or second surfaces of the first lens according to embodiments of the present disclosure. [Figure 24] Figure 24 is a schematic diagram of a computer system according to one embodiment. [Modes for carrying out the invention]

[0019] Figure 1A shows a side view of a display system (e.g., a near-eye display system) (100) according to several embodiments of the present disclosure. The display system (100) includes an optical system (110), a shift block (170), and a controller (180). The optical system (110) may include a display device (120), a lens system (130), a beam splitter (141), a reflective polarizer (139), and a quarter-wave plate (QWP) (142). The display device (120) may include a pixel array configured to emit a light beam to display an image. The lens system (130), beam splitter (141), reflective polarizer (139), and QWP (142) can direct the light beam emitted from the display device (120) to a region (151). In one example, the region (151) is located in the XY plane and is called the exit pupil of the optical system (110). The XY plane includes the X-axis and the Y-axis perpendicular to the X-axis. A light-receiving or light-detecting unit, such as the user's eye (60), can be positioned in the region (151). In one example, the lens (63) of the eye (60) forms an image on the retina (65) of the eye (60), and therefore the eye (60) perceives the image on the display device (120) as a virtual image, such as the virtual image (199) in Figure 1A. The virtual image (199) appears at a distance D2 from the region (151) and appears larger than the image on the display device (120). The distance D2 is greater than, and in some cases much greater than, the distance D1 between the region (151) and the display device (120).

[0020] Referring to Figure 1A, an optical resonator is formed between the beam splitter (141) and the reflective polarizer (139). The optical resonator may include a lens system (130) and a QWP (142). As will be described later, the optical path of the light rays in the light beam is folded back in the optical resonator between the beam splitter (141) and the reflective polarizer (139). Thus, the optical system (110) can be configured to be positioned within a distance threshold (e.g., 35 mm) of the user's eye (e.g., eye (60)), and the display system (100) can be called a near-eye display (NED) system. The display system (100) is, for example, a head-mounted display (HMD) system worn by the user.

[0021] According to one embodiment of the present disclosure, the lens system (130) may include a first lens (131) and a second lens (132). In one example, the second lens (132) is a focusing lens. At least one of (i) a first surface (135) and (ii) a second surface (136) of the first lens (131) is aspherical. The shape of the aspherical surface may include a wavy shape, as will be described later.

[0022] For clarity, the first lens (131), region (151), and display device (120) are shown again in Figure 1B. The optical axis (160) of the lens system (130) is also the optical axis of the first lens (131). The optical axis (160) is parallel to the Z axis, which is perpendicular to the XY plane.

[0023] Referring to Figure 1B, in one example, the inner surface (161) of the first surface (135) is convex or curves outward toward the display device (120), and the outer surface (162) of the first surface (135) is concave or curves away from the display device (120). The inner surface (161) can be surrounded by the outer surface (162) of the first surface (135).

[0024] For clarity, the first lens (131), region (151), and display device (120) are again depicted in Figure 1C. Referring to Figure 1C, the thickness of the first lens (131) varies along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). For example, the thickness of the first lens (131) decreases from Tc (e.g., the thickness at the center of the first lens (131)) to a minimum thickness Ts at the boundary (184), and thereafter, the thickness of the first lens (131) increases from the boundary (184) to a thickness Te (e.g., edge thickness) at the edge of the first lens (131). As will be described later, the first lens (131) having the above shape and / or thickness profile can, for example, compensate for the aberration of the second lens (132) and reduce the overall aberration of the lens system (130). Therefore, the display system (100) using the lens system (130) can produce virtual images with higher resolution (e.g., the ability of the display system (100) to distinguish details of objects) and a wider field of view (FOV) while miniaturizing the display system (100).

[0025] The display system (100) may be a component of the artificial reality system. The artificial reality system can adjust reality in some way to an artificial reality and then present the artificial reality to the user. The artificial reality may include, for example, virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or any combination and / or derivative thereof. The artificial reality content may include entirely generated content, or a combination of generated content and captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or any combination thereof, any of which can be presented on a single channel or multiple channels (such as stereo video that produces a three-dimensional effect for the user).

[0026] In some cases, the display system (100) can be applied to the playback of live or pre-recorded video.

[0027] In one embodiment, the “near-eye” display system may include an optical system (e.g., including one or more optical elements) configured to be positioned within a distance threshold of the user’s eye when the NED system (100) (e.g., an HMD or smart glasses) is in use. Referring to Figure 1A, the distance D1 between the display device (120) and the area (151) may be less than or equal to the distance threshold. In one example, the distance D1 is the distance between the display device (120) and the eye (60).

[0028] The display system (100) may be an NED system implemented in various forms such as an HMD system, smart glasses, or a smartphone. In some examples, the artificial reality system is implemented as a standalone NED system. In some examples, the artificial reality system is implemented as an NED system connected to a host computer system such as a server device or console device.

[0029] The display device (120) may include a pixel array. In some examples, the pixel array includes a plurality of pixels arranged to form a two-dimensional surface. The two-dimensional surface of the display device (120) may be substantially flat or planar, curved, or include a combination of flat and planar panels. The display device (120) may be a display panel. The display device (120) may include any suitable type of display panel, such as a liquid crystal display (LCD) panel or an organic light-emitting diode (OLED) panel. The resolution of the display device (120) can be defined according to the two dimensions of the two-dimensional surface or to a pixel in one of the two dimensions. Each pixel in the pixel array can generate a light beam. Each light beam may include a bundle of rays in any suitable direction. For example, pixel A on the display device (120) emits a light beam containing a bundle of rays in a suitable direction. A subset of rays (124) in the light beam can be directed towards a region (151) by a lens system (130). The angular span of a subset of the light beam (124) can be determined based on the allowable angle ω of the lens system (130). Three rays (121) to (123) of the subset of the light beam (124) are shown in Figure 1A. The three rays (121) to (123) may include two boundary rays (121) and (123) and a central ray (122).

[0030] Generally, a light beam is randomly polarized if it contains a series of rapidly changing polarization states. A light beam can be linearly polarized (e.g., in a linearly polarized state), circularly polarized (e.g., in a circularly polarized state), elliptically polarized (e.g., in an ellipticly polarized state), and so on. For linearly polarized light, the electric field vector of the light beam follows a specific line. For circularly polarized light, the electric field vector of the light beam rotates, for example, clockwise or counterclockwise, as viewed from an observer in the direction of light beam propagation.

[0031] Degree of polarization (DOP) is a quantity that indicates the polarized portion of an electromagnetic wave (e.g., a light beam). Perfect polarization can have a DOP of 100%, while unpolarized polarization can have a DOP of 0%. Partial polarization can be represented by the superposition of polarized and unpolarized components, and therefore can have a DOP between 0% and 100%. DOP can be calculated as the proportion of the total power carried by the polarized component of the wave (e.g., a light beam).

[0032] A light beam (for example, a light beam generated from each pixel) can have any suitable polarization state or DOP. In one example, the light beam is circularly polarized with 100% DOP. In another example, the light beam is primarily circularly polarized with a relatively large DOP above a threshold (e.g., 80% or more), such as a superposition of (i) a circularly polarized component and (ii) a non-polarized component and / or another polarization component. Hereinafter, a circularly polarized light beam with 100% DOP, or a primarily circularly polarized light beam with a relatively large DOP, can be referred to as a circularly polarized light beam. In another example, the light beam is linearly polarized with 100% DOP, or primarily linearly polarized with a relatively large DOP above a threshold. Hereinafter, a linearly polarized light beam with 100% DOP, or a primarily linearly polarized light beam with a relatively large DOP, can be referred to as a linearly polarized light beam.

[0033] According to one embodiment of the present disclosure, the light beam generated by the display device (120) may be circularly polarized or linearly polarized.

[0034] The lens system (130) can be configured to modify the light beam generated by the display device (120) and direct the modified light beam toward the region (151). In some embodiments, the lens system (130) may include diffraction elements (gritzes and prisms), refractive elements (lenses), guide elements (e.g., plane waveguides and / or fibers), and polarizing elements (e.g., polarizers, half-wave plates, quarter-wave plates, polarizing rotors, Pancharatnam-Berry phase lenses (PBP), etc.). In the example shown in Figure 1A, the lens system (130) includes a first lens (131) and a second lens (132). The lens system (130) may have an optical axis (160). In one example, each of the first lens (131) and the second lens has circular symmetry about the optical axis (160). The optical axis (160) is also the optical axis of the second lens (132).

[0035] A first lens (131) can be placed between the display device (120) and the region (151). A second lens (132) can be placed between the first lens (131) and the display device (120). In one example, the first lens (131) can be called an eye lens because it is close to the region (151) (e.g., an eye (60)), and the second lens (132) can be called a display lens because it is close to the display device (120). The first lens (131) and the second lens (132) can be separated by a gap or space (133). In the example shown in Figure 1A, the gap is greater than 0. In one example, a portion of the first lens (131) is in contact with a portion of the second lens (132), for example, the minimum distance between the first lens (131) and the second lens (132) is zero.

[0036] The first lens (131) may include an optically transparent member (145) having a first surface (135) and a second surface (136). The first surface (135) may face the display device (120). The optically transparent member (145) may be configured to receive a light beam from the display device (120) through the first surface (135). The optically transparent member (145) may include any suitable material such as glass, polymer, or plastic material. In one example, the optically transparent member (145) may include poly(methyl methacrylate) (PMMA), polyimide, acrylic, styrene, cyclic olefin polymer, cyclic olefin copolymer, polycarbonate, etc. The first surface (135) and / or the second surface (136) of the first lens (131) may have any suitable shape, such as a planar shape parallel to the XY plane, a spherical shape with any suitable radius of curvature, an aspherical shape, or another shape.

[0037] The second lens (132) may include an optically transparent member (146) having a first surface (137) and a second surface (138). The first surface (137) may face the display device (120). The optically transparent member (146) may be configured to receive a light beam from the display device (120) through the first surface (137). The optically transparent member (146) may include any suitable material such as glass, polymer, or plastic material. In one example, the optically transparent member (146) may include glass such as borosilicate glass (e.g., BK7 glass) or high-density flint glass (e.g., SF1 glass). The first surface (137) and / or the second surface (138) of the second lens (132) may have any suitable shape such as a planar shape parallel to the XY plane, a spherical shape with any suitable radius of curvature, an aspherical shape, or another shape.

[0038] Generally, glass lenses (e.g., second lens (132)) can be manufactured by grinding and polishing, glass forming methods, etc. Polymer or plastic lenses (e.g., first lens (131)) can be manufactured by diamond turning, polishing, injection molding, casting, etc.

[0039] According to one embodiment of the present disclosure, at least one of the first surface (135) and the second surface (136) of the first lens (131) is aspherical. The second lens (132) is a focusing lens in which the first surface (137) is spherical (for example, convex or curved toward the display device (120)) and the second surface (138) is a plane parallel to the XY plane.

[0040] A beam splitter (141) and a reflective polarizer (139) can be placed between the region (151) and the display device (120). A quarter-wave plate (142) can be placed between the beam splitter (141) and the reflective polarizer (139). An anti-reflective (AR) coating can be applied to any suitable surface of the lens system (130) to reduce undesirable reflections of the light beam. In one example, the AR coating is applied to the first surface (135) of the first lens (131) and the second surface (138) of the second lens (132), respectively.

[0041] A beam splitter (141) can be configured to partially transmit and partially reflect a light beam incident on it. The beam splitter (141) may have an average light transmittance T and an average light reflectance R. In one example, the sum of T and R is 1 (i.e., 100%) over a wavelength range (e.g., 380 to 780 nanometers (nm)). The average light transmittance T and average light reflectance R of the beam splitter (141) can be referred to as T / R. T or R may be within a range (e.g., 40% to 60%). In one example, the beam splitter (141) may have a T / R of 40 / 60, 50 / 50, or 60 / 40. For example, if T and R are 50%, the beam splitter (141) transmits 50% of the light beam incident on it and reflects 50%. Generally, a beam splitter may include one or more thin films coated or deposited on the surface of a lens (e.g., a second lens (132) or a first lens (131)) within the lens system (130). In one example, a beam splitter (141) is formed on the first surface (137) of the second lens (132), as shown in Figures 1A and 1D, and the beam splitter (141) may include one or more thin films coated or deposited on the first surface (137) of the second lens (132). The beam splitter (141) transmits a portion of the light beam from the display device (120) and reflects a portion of it.

[0042] The polarization state of a light beam can change when it passes through a particular optical element. In one embodiment, the polarization state of a light beam can be changed by a waveplate or retarder when the light beam passes through a waveplate. A quarter-wave plate (142) can change the polarization state of a light beam passing through it by 90° or π / 2. In one example, the quarter-wave plate (142) converts linearly polarized light to circularly polarized light, or vice versa. The quarter-wave plate (142) can be formed on the surface of the first lens (131) or the second lens (132), such as the first surface (135), the second surface (136), the first surface (137), and the second surface (138).

[0043] A reflective polarizer (139) can be configured to allow a light beam in a first linearly polarized state to pass through and to reflect a light beam in a second linearly polarized state. The second linearly polarized state is orthogonal to the first linearly polarized state. The reflective polarizer (139) may include one or more layers of an optical film. In one example, the reflective polarizer (139) is formed on the surface of the first lens (131) and the second lens (132), such as the second surface (136) of the first lens (131).

[0044] Referring to Figure 1A, the beam splitter (141), quarter-wave plate (142), and reflective polarizer (139) are curved to conform to the shape of the respective surfaces of the first lens (131) or the second lens (132).

[0045] Referring to Figure 1A, a beam splitter (141) is positioned on the first surface (137) of the second lens (132), and a reflective polarizer (139) is positioned on the second surface (136) of the first lens (131). A quarter-wave plate (142) is formed on the second surface (138) of the second lens (132). An optical resonator can be formed between the beam splitter (141) and the reflective polarizer (139). The optical resonator may include the first lens (131), the second lens (132), a gap (133), and a QWP (142).

[0046] A portion of the light beam emitted from the display device (120) can pass through the beam splitter (141). Subsequently, the light beam passes through the optical resonator multiple times. In one example, the light beam passes through the optical resonator for the first time and is reflected by the reflective polarizer (139). Then, the light beam passes through the optical resonator again and is partially reflected by the beam splitter (141). After the third passage through the optical resonator, the light beam passes through the reflective polarizer (139) and reaches region (151).

[0047] The optical system (110) includes a reflector-refractor optical system. For example, the reflector-refractor optical system (110) includes (i) refractive optical components (e.g., a lens system (130) and a beam splitter (141)) and (ii) reflective optical components (e.g., a beam splitter (141) and a reflective polarizer (139)).

[0048] The reflecting-refracting optical system (110) may include a polarizing reflecting-refracting optical system. For example, each time the light beam passes through the QWP (142), the polarization state of the light beam is manipulated by the QWP (142). Thus, after the first pass, the light beam is in one polarization state and is reflected by the reflective polarizer (139), and after passing through the optical resonator three times, the light beam is in another polarization state and is transmitted through the reflective polarizer (139).

[0049] The optical system (110) can also be called a folded optical system. When the light beam is reflected between the beam splitter (141) and the reflective polarizer (139) and travels through the optical resonator multiple times (e.g., three times), the optical path between the display device (120) and the region (151) includes a folded path (125) between the beam splitter (141) and the reflective polarizer (139). By folding the optical path, the distance D1 can be reduced, and the display system (100) including the optical system (110) can be used as a NED system. In one example, the lens system (130) is designed to have a relatively small thickness D5 and can be called a pancake lens system.

[0050] Referring to Figure 1A, a portion of the light ray (122) emitted from pixel A of the display device (120) passes through the beam splitter (141). Subsequently, the light ray (122) passes through the optical resonator for the first time, and then sequentially passes through the optically transparent member (146), QWP (142), gap (133), and optically transparent member (145).

[0051] After the light ray (122) first passes through the optical resonator, the light ray (122) is reflected back into the optical resonator by the reflective polarizer (139). Subsequently, the light ray (122) passes through the optical resonator again and then sequentially through the optically transparent member (145), the gap (133), the QWP (142), and the optically transparent member (146).

[0052] After the ray (122) passes through the optical resonator again, a portion of the ray (122) is reflected back into the optical resonator by the beam splitter (141). Subsequently, the ray (122) passes through the optical resonator a third time, passing through the optically transparent member (146), QWP (142), gap (133), and optically transparent member (145) in sequence. Then, the ray (122) passes through the reflective polarizer (139) and proceeds to the region (151). In one example, the ray (122) is focused onto the retina (65) by the lens (63) of the eye (60), and the eye (60) perceives the ray (122) as if it were coming from a virtual point A'' on the virtual image (199).

[0053] According to one embodiment of the present disclosure, a light beam emitted from a pixel (including, for example, pixel A) in a display device (120) may be circularly polarized, for example, in a first circularly polarized state. A beam splitter (141) transmits a portion of the light ray (122) in the first circularly polarized state. The light ray (122) then passes through the optical resonator for the first time as described above. During this first passage, the first circularly polarized state of the light ray (122) is converted to a second linearly polarized state by the QWP (142). The second linearly polarized state is along the blocking direction of the reflective polarizer (139). The blocking direction of the reflective polarizer (139) refers to the direction in which the light beam is blocked by the reflective polarizer (139) and does not pass through the reflective polarizer (139) when the electric field vector of the light beam is along the blocking direction. The reflective polarizer (139) reflects the ray (122) in the second linearly polarized state with a relatively high average reflectivity, for example, a value (e.g., 90%) or more over a wavelength range (e.g., 380 nm to 780 nm). The ray (122) then passes through the optical resonator again as described above, and a portion of the ray (122) is reflected by the beam splitter (141). Subsequently, the ray (122) passes through the optical resonator a third time as described above. In both the second and third passes, the QWP (142) changes the polarization state of the ray (122). This converts the second linearly polarized state of the ray (122) to a first linearly polarized state parallel to the transmission direction of the reflective polarizer (139). Therefore, the reflective polarizer (139) transmits the light ray (122) in a first linearly polarized state such that the light ray (122) is directed towards the region (151) with a relatively high transmittance of a value (e.g., 90%) or more over a wavelength range (e.g., 380 nm to 780 nm).

[0054] Referring to Figure 1A, the optical path includes a folding path (125) between the reflective polarizer (139) and the beam splitter (141) due to polarization change. In one example, the QWP (142) has two axes in the XY plane (e.g., a high-speed axis and a low-speed axis). One of the two axes of the QWP (142) is oriented at 45° with respect to the axis of the reflective polarizer (139).

[0055] To achieve high-quality imaging, the reflective polarizer (139) needs to be of high quality, such as having high reflectivity in the blocking direction (e.g., high average reflectivity), high transmittance in the passing direction (e.g., high average transmittance), and relatively low surface roughness. Furthermore, the AR coating can be applied to any suitable surface of the optical system (110), such as the first surface (135) of the first lens (131) and the second surface (138) of the second lens (132), in order to reduce or eliminate ghosting due to multiple reflections at various interfaces.

[0056] Polarized reflector-refracting optical systems are a novel solution for virtual reality HMDs. A good VR optical system can accommodate a wide range of interpupillary distances and include a large pupillary volume (also called an eyebox) to allow eye rotation as the user surveys the entire field of view (FOV). In one example, the eyebox represents the volume from which the eye receives an acceptable view of the image. The size and position of the eyebox may be related to several constraints, such as FOV and image quality. In one example, the eyebox represents the range of eye positions from which the image produced by the optical system (110) can be viewed at the eye relief distance. The eyebox can include eye movements such as eye rotation and / or lateral movement.

[0057] Refractive power can indicate the degree to which an optical system or optical component (e.g., a lens or curved mirror) focuses or diverges light. In one example, the refractive power of an optical component or optical system is equal to the reciprocal of its focal length f. A higher refractive power indicates (i) a stronger focusing power for a converging optical component / system, or (ii) a stronger divergent power for a diverging optical component / system.

[0058] In polarized reflector-refracting optical systems such as optical system (110), folded optical paths (e.g., folded path (125)) can be used to achieve relatively large refractive power in a compact form factor. In the example shown in Figure 1A, the beam splitter (141) is a curved mirror that reflects some of the light and transmits some of it, and the reflective polarizer (139) is a curved mirror that reflects or transmits light depending on the polarization state of the light. In general, the design freedom available in folded optical systems (e.g., optical system (110)) can benefit HMD systems. Advantages include high resolution achieved by reflective imaging, a wide FOV (e.g., by using low-aberration lenses), compact size, reduced weight, the possibility of adjusting focus, and the formation of a larger eyebox. FOV can represent the extent of the observable world seen or detected by the photodetector (also called a photosensor). In one example, FOV is represented by the solid angle at which the photodetector can detect or receive light. The optical system (110) shown in Figure 1A can be manufactured by controlling the curved shape and surface finish of the first lens (131) and the reflective polarizer (139) placed on the first lens (131). A pancake optical system (e.g., optical system (110)) can provide a comfortable and immersive user experience.

[0059] The optical system (110) can have a large pupil volume to accommodate a variety of interpupillary distances and allow eye rotation as the user surveys the entire field of view. Interpupillary distance (IPD) is the distance between the centers of the pupils of the user's eyes. IPD can vary with respect to age, sex, etc. The optical system (110) can be designed to accommodate variations in IPD so that the optical system (110) can accommodate a variety of users with different IPDs. In one example, IPD can range from approximately 50 to 80 mm.

[0060] In one example, to enable a user to enjoy VR without prescription glasses or with dynamic focus, the optical system (110) can adjust the diopters of the lenses in the lens system (130) to match the prescription. In one example, the diopters represent the virtual object distance. Increasing the diopters makes objects appear closer. Focus adjustment can be achieved by changing the refractive power of the optical system. The refractive power of a folded mirror resonator (e.g., an optical resonator between a beam splitter (141) and a reflective polarizer (139)) can be changed by changing the cavity length (or gap) relative to a reference cavity length corresponding to a reference refractive power.

[0061] Considering human factors such as human vision (e.g., field of view of the human eye, eye rotation) and head rotation can be helpful in designing the optical parameters of the optical system (110). Optical designs with high resolution across the range of eye rotation can make the user's visual experience more natural.

[0062] Spontaneous or involuntary eye rotation may be less than 20°. Figure 2 shows examples of eye and head rotation. Unconscious horizontal eye rotation is less than a value to the left or right of the center (e.g., 20°), and may be, for example, 15°±2°. Conscious horizontal eye rotation can be greater than unconscious horizontal eye rotation. In one example, conscious horizontal eye rotation may be a value such as 30°±2°. In another example, the eyes may rotate approximately 28°±8° upwards and 47°±8° downwards. Figure 2 also shows an example of natural head movement. In one example, natural head movement is 45°±2° horizontally.

[0063] In one example, a human's horizontal field of view, without eye movement, slightly exceeds 210°. The horizontal field of view (FOV) of both human eyes can be 210°. The vertical range of a human's field of view (or vertical FOV) is approximately 150°.

[0064] The human eye is not a perfect lens across the entire large field of view (FOV). Visual acuity can indicate the clarity or sharpness of vision. Eccentricity can refer to the angular distance from the center of the field of view or from the fovea of ​​the retina. Figure 3 shows the relationship between visual acuity (including peripheral vision) and eccentricity. Visual acuity can decrease with eccentricity. Therefore, unless the eye is rotated to directly gaze into the peripheral field of view, the eye will lack visual acuity in the peripheral field, and thus the resolution of the optical system in the peripheral field of view can be lower than the resolution of the optical system in the central field of view. By considering visual acuity, over-design of the optical system can be avoided.

[0065] Embodiments of the present disclosure include a sharp (e.g., having high resolution) and compact (e.g., small in size) polarizing reflective refractive VR optical system that utilizes one or more corrugated lenses (e.g., a first lens (131) having one or more corrugated surfaces) to achieve a wide FOV. The first lens (131) may have a corrugated shape so that the display system (100) can have a relatively short lens track length (e.g., 12 to 18 mm), a relatively large display size (e.g., a diagonal length of 1.4 to 2.6 inches), a relatively large lens diameter (e.g., ≥45 mm), and / or a large FOV (e.g., ≥90°). The lens track length can represent the distance between the display device (120) and the first lens (131) (e.g., the last optical component in the optical system (110) before the region (151). Referring to Figure 1A, the lens track length is the distance along the optical axis (160) between the display device (120) and the first lens (131). The display size can indicate the size of an area on the display device (120) from which a light beam emitted can be received by an area (151) such as an eye (60). The display size can be expressed as the diagonal length, radius (for example, if the area on the display device (120) is circular), etc. The lens diameter can indicate the size of a portion of the first lens (131) that allows light to pass through and / or the size of a portion of the second lens (132). In one example, the size of the portion of the first lens (131) that allows light to pass through and the size of the portion of the second lens (132) that allows light to pass through are the same, and the lens diameter can indicate the size of both the portion of the first lens (131) that allows light to pass through and the portion of the second lens (132).

[0066] According to one embodiment of the present disclosure, the second lens (132) is a planar-spherical lens. The first surface (137) and the second surface (138) of the second lens (132) are spherical and planar, respectively. The second lens (132) is a focusing lens. The first lens (131) is an aspherical-aspherical lens in which the first surface (135) and the second surface (136) of the first lens (131) are aspherical. Referring to Figure 1A, a beam splitter (141) is positioned on the first surface (137) of the second lens (132), and the second lens (132) may also be called a beam splitter lens. A reflective polarizer (139) is positioned on the second surface (136) of the first lens (131), and the first lens (131) may also be called a reflective polarizer lens. In one example, the lens system (130) includes a beam splitter (141) and a reflective polarizer (139).

[0067] Referring to Figure 1B, in order to reduce the aberration of the second lens (132), at least one of (i) the first surface (135) and (ii) the second surface (136) of the first lens (131) has an aspherical shape. The aspherical shape may include a wavy or gull-wing shape. For example, the inner surface (161) of the first surface (135) is convex or curves toward the display device (120), and the outer surface (162) of the first surface (135) is concave or curves toward the display device (120). The inner surface (161) can be surrounded by the outer surface (162) of the first surface (135).

[0068] In one embodiment, the curve formed by the intersection of the first surface (135) of the first lens (131) and the cross-sectional plane may have at least four inflection points I1 to I4. The cross-sectional plane may be an XY plane parallel to the optical axis (160) of the lens system (130). Since Figure 1B shows a cross-sectional view of the first lens (131), the curve formed by the intersection of the first surface (135) of the first lens (131) and the XY plane is also shown by the first surface (135).

[0069] Referring to Figure 1C, as described above, the thickness of the first lens (131) decreases from Tc at the optical axis (160) (for example, along the center) of the first lens (131) until the thickness reaches a minimum thickness Ts at the boundary (184), and thereafter the thickness of the first lens (131) increases from the boundary (184) toward the edge of the first lens (131) to a thickness Te. In the central region (181) of the first lens (131), the thickness of the central region (181) changes along the Y axis, for example, decreasing from Tc to Ts. In the peripheral region (182) of the first lens (131), the thickness changes along the Y axis, for example, increasing from Ts at the boundary (184) to Te at the edge of the first lens (131).

[0070] In one embodiment, the light beam passing through the first lens (131) and the second lens (132) may include a first light beam and a second light beam, with the first light beam being closer to the optical axis (160) than the second light beam. Due to the aberration of the second lens (132), when the first and second light beams pass through the second lens (132), the second light beam may experience a stronger focusing force than the first light beam. Due to the wavy shape of the first lens (131) as described above, as shown in Figures 1A to 1C, a first region within the first lens (131) located on or close to the optical axis (160) may have a greater focusing force for a first light beam incident on the first region than a second region of the first lens (131) near the edge of the first lens (131) has for a second light beam incident on the second region. Therefore, a stronger focusing force on the second light beam at the second lens (132) can be compensated for by reducing the focusing force on the second light beam at the first lens (131), and thus the aberration of the lens system (130) can be reduced.

[0071] In one example, both the first and second regions of the first lens (131) act as condensing lenses, with the first region having a stronger focusing force than the second region. In another example, the first region of the first lens (131) acts as a condensing lens, and the second region of the first lens (131) acts as a diverging lens.

[0072] Figure 1D shows an exemplary ray tracing according to one embodiment of the present disclosure. Pixel B on a display device (120) generates a light beam. The light beam from pixel B can travel along various directions with an angular span between boundary rays (195) and (196). A subset of rays (126) of the light beam can be directed towards a region (151) by a lens system (130). The subset (126) of the light beam from pixel B may have a first cone angle (e.g., a first angular span of the subset (126) of the light beam). In some examples, rays outside the first angular span of the subset (126) of rays do not reach the region (151). The first angular span may be smaller than the angular span of the light beam from pixel B. Four rays within the subset (126) are shown in Figure 1D. For clarity, an arrow has been added to one of the four rays. As described above, the optical path of subset (126) includes a folded optical path between the beam splitter (141) and the reflective polarizer (139).

[0073] The subset (126) is incident on the region (191) of the second lens (132) that is closer to the edge of the second lens (132) and is subjected to a stronger focusing force than the light beam incident on the central region (193) of the second lens (132) that is closer to the optical axis (160). Light beams from other pixels (e.g., including pixel A in Figure 1A) can be incident on the central region (193) of the second lens (132). Light beams from other pixels reach region (151) and can subsequently form a sharp image of the other pixels on the retina (65) of the eye (60) located in region (151). However, aberrations of the second lens (132) (e.g., spherical aberration) may result in a spot in front of the retina (65) for pixel B. Therefore, without aberration compensation, pixel B will appear blurred. Due to the shape of the first surface (135) and / or the second surface (136) of the first lens (131), the region (192) within the first lens (131) into which the subset (126) is incident is less focused than the central region of the first lens (131) which is closer to the optical axis (160). Thus, the aberration of the second lens (132) is compensated for, resulting in a spot on the retina (65) for pixel B. Thus, due to the compensation for aberration, pixel B appears sharp. As illustrated in Figure 1A, the eye (60) perceives a virtual image (e.g., (199)) located at a distance D2 from region (151) for pixel B and other pixels.

[0074] Referring to Figure 1D, the subset (126) is transformed into a light beam (127) reaching region (151). In one example, the light beam (127) is collimated, and the rays within the collimated light beam (127) are parallel. To the eye (60), the collimated light beam (127) appears as a virtual image at infinity, and the muscles of the eye (60) relax when viewing a virtual image at infinity. In general, the subset (126) can be relatively collimated such that the virtual image (199) appears to be at a finite distance from the eye (60) (for example, D2 is finite). The distance D2 can be made relatively large so that the muscles of the eye (60) are relatively relaxed.

[0075] Referring to Figure 1D, a subset (126) of the light beam from pixel B may have a first cone angle determined, for example, based on the light intensity distribution of the light emitted from pixel B (due to the rays between boundary rays (195) and (196)) and the allowable angle ω of the lens system (130). The light beam (127) reaching region (151) may have a second cone angle based on the optical system (110) (e.g., a second angular span of the light beam (127)). In one embodiment, the subset (126) may be relatively collimated, and the second cone angle may be smaller (e.g., much smaller) than the first cone angle.

[0076] Various examples of optical systems (110) including a lens system (130) are given. In each of the following examples, the lens system (130) includes a first lens (e.g., a curved-reflecting polarizer lens) (131) which is an aspherical-aspherical lens, and a second lens (132) which is a planar-spherical lens, as shown in Figures 1A and 1D. The first surface (135) of the first lens has, for example, a wavy shape, and the thickness variation may be as described above with reference to Figures 1B to 1D. The diameters of the first lens (131) and the second lens (132) may be greater than or equal to a value (e.g., 46 mm) such that the FOV is 90° or greater at an eye relief of 15 mm. The optical system (110) can form a virtual image (199) from an image on a display device (120) for a suitable range of multicolor wavelengths, such as visible wavelengths (e.g., 380 nm to 780 nm with a bandwidth of 400 nm) or multicolor wavelengths close to green (e.g., 500 nm to 540 nm with a bandwidth of 40 nm).

[0077] In the first example, referring to Figure 1D, the distance D3 (also called eye relief) between region (151) and the first lens (131) (e.g., the last optical component in the optical system (110) in front of region (151) is 15 mm. The distance D4 (i.e., lens track length) between the display device (120) and the first lens (131) is 15.5 mm. In one example, D1 is equal to the sum of D3 and D4. The display size is indicated by the display image circle imaged onto region (151) by the optical system (110), the display image circle having a radius of 18.9 mm. The FOV of the optical system (110) is 110°. Figures 4 and 5 show the first shapes of the first surface (135) and the second surface (136) of the first lens (131), and Figures 6 to 10 show the performance of an optical system (110) using the first lens (131) having the first shape shown in Figures 4 and 5 according to one embodiment of the present disclosure.

[0078] Sagitter or sag can indicate the material removed to obtain an optical surface (or optical curve). In one example, with respect to a sphere, sag is the displacement along the optical axis from a vertex of the sphere at a position away from the optical axis. Figure 4 shows the relationship between the sag (in mm) of the second surface (136) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) of the first lens (131) (e.g., the Y-axis). In one example, referring to Figure 1B, the sag shown in Figure 4 indicates the distance along the optical axis (160) between line (171) and each point on the curve (136) formed by the intersection of the second surface (136) of the first lens (131) and the XY plane. Line (171) passes through the vertex V2 of the second surface (136) and is tangential to the second surface (136).

[0079] Figure 4 shows an example in which the second surface (136) of the first lens (131) has a wavy shape similar to the wavy shape of the first surface described in Figure 1B. For example, the curve formed by the intersection of the second surface (136) of the first lens (131) and the cross-sectional plane may have at least four inflection points (not marked). Similarly, the inner surface of the second surface (136) closer to the optical axis (160) is curved toward the display device (120), and the outer surface of the second surface (136) further from the optical axis (160) is curved toward the display device (120).

[0080] In Figure 4, (i) the minimum sagittal S at a first position (e.g., approximately 21 mm or -21 mm) of the second surface (136) of the first lens (131). min (ii) the maximum sagittal S at the second position (e.g., 0 mm) of the second surface (136) of the first lens (131) max The sagittal difference between them is 0.6 mm to 0.8 mm.

[0081] Figure 5 shows the relationship between the sag (in mm) of the first surface (135) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the sag in Figure 5 is the distance along the optical axis (160) between line (172) and each point on the curve (135) formed by the intersection of the first surface (135) of the first lens (131) and the XY plane. Line (172) passes through the vertex V1 of the first surface (135) and is tangential to the first surface (135). In Figure 5, (i) the minimum sag S at a first position (e.g., approximately 21 mm or -21 mm) of the first surface (135) of the first lens (131). min (ii) the maximum sagittal S at the second position (e.g., 0 mm) of the first surface (135) of the first lens (131) max The sagittal difference between these two values ​​is between 1.5 millimeters (mm) and 2.5 mm.

[0082] Referring to FIG. 5, the wavy shape of the first surface (135) can be shown by the relationship between the sag of the first surface (135) and the position along the Y-axis. For example, a curve (511) showing the sag of the first surface (135) with respect to the position along the Y-axis has four inflection points (521)-(524). The sag can oscillate multiple times (e.g., twice in FIG. 5) as the position along the Y-axis changes, thus showing the wavy shape of the first surface (135).

[0083] The lens diameter can indicate the size of the portion of the first lens (131) that allows light to pass through. In one embodiment, the lens radius can be, for example, less than or equal to the maximum position along the Y-axis (e.g., 32 mm in FIGS. 4 and 5), and the lens diameter can be, such as 64 mm in FIGS. 4 and 5, less than or equal to twice the maximum position.

[0084] The resolution of an optical system can indicate the ability of the optical system to distinguish details of an object. In one example, the resolution is expressed in lines per millimeter (lp / mm), where a line pair is an arrangement of one black line and one white line.

[0085] The contrast or modulation of an image can be defined as contrast (%) = (I max -I min ) / (I max +I min ), where I max and I min represent the maximum intensity and minimum intensity of the image, respectively. <​​​​​The sagitta line used to determine the MTF can refer to a line that radiates from the center outwards from the edge of the image circle. The tangent line (or meridian) is perpendicular to the sagitta line. The optical system does not necessarily focus the lines in both directions equally on the same plane, and therefore the sagitta and tangent measurements of the same optical system may differ. The MTF may be a sagitta MTF if the sagitta line is used to determine the MTF, or a tangent MTF if the tangent line is used to determine the MTF.

[0088] Figures 6 to 9 show the MTF of an optical system (110) using a first lens (131) having the first shape shown in Figures 4 and 5. In Figure 6, the eye (60) is positioned in region (151) gazing straight ahead without rotation (e.g., field of view or eye rotation is 0°). Figure 6 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (601) to (603) represent the sagittal MTF for field of view angles from 0° to 50° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (611) to (613) represent the tangent MTF for field of view angles from 0° to 55° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0089] In Figure 7, the eye (60) is positioned in region (151) gazing at a field of view of 10°. Figure 7 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (701) to (703) represent the sagittal MTF for field of view from 0° to 45° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (711) to (713) represent the tangent MTF for field of view from 0° to 45° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0090] In Figure 8, the eye (60) is positioned in region (151) and gazing at a field of view of 20°. Figure 8 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (801) to (803) represent the sagittal MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (811) to (813) represent the tangent MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0091] In Figure 9, the eye (60) is positioned in region (151) and staring at a field of view of 30°. Figure 9 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (901) to (903) represent the sagittal MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (911) to (913) represent the tangent MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0092] Referring again to Figures 6-9, the MTF can vary with resolution (e.g., 5, 10, or 20 lp / mm) and / or eye gazing angle. In particular, the MTF at a resolution of 20 lp / mm is greater than 80% at a 0° field of view and eye rotation to 0°, the MTF at a resolution of 20 lp / mm is greater than 40% at a 10° field of view and eye rotation to 10°, the MTF at a resolution of 20 lp / mm is greater than 25% at a 20° field of view and eye rotation to 20°, and the MTF at a resolution of 10 lp / mm is greater than 25% at a 30° field of view and eye rotation to 30°. Figures 6-9 show that the FOV can be 110° (e.g., from a -55° field of view to a 55° field of view) at a resolution of 10 lp / mm.

[0093] Figure 10 shows relative light intensity for field of view angles from 0° to 55°. Relative light intensity can represent the intensity of illuminance per unit area of ​​the image surface, normalized to the illuminance at a point in the field of view with maximum illuminance. In one example, relative light intensity analysis calculates relative light intensity as a function of the radial field of view coordinates of a uniform Lambertian scene. Over the entire FOV (e.g., 110°), the relative light intensity is above 80% or 0.8.

[0094] Figures 11A and 11B show a second example of a display system (100) including an optical system (110). The optical system (110) includes a display device (120). The display device (120), region (151), and eye (60) are described in Figure 1A. The optical system (110) includes a lens system (1130). The lens system (1130) includes a first lens (e.g., a curved reflective polarizer lens) (1131) which is an aspherical-aspherical lens, and a second lens (1132) which is a planar-spherical lens. The first surface (1135) of the first lens (1131) has an aspherical (e.g., wavy) shape similar to the first surface (135) of the first lens (131) described above with reference to Figures 1B and 1D. The first lens (1131) has a thickness variation similar to the first lens (131) described above with reference to Figure 1C. The diameters of the first lens (1131) and the second lens (1132) may be greater than or equal to a value (e.g., 46 mm) such that the field of view (FOV) is 100° or greater with an eye relief of 15 mm. The optical system (110) in Figure 11A can form a virtual image (199) from an image on a display device (120) for a suitable range of multicolor wavelengths, such as visible wavelengths (e.g., 380 nm to 780 nm with a bandwidth of 400 nm) or multicolor wavelengths close to green (e.g., 500 nm to 540 nm with a bandwidth of 40 nm).

[0095] The first lens (1131) and the second lens (1132) are separated by a gap (1133). The first lens (1131) may include an optically transparent member (1145) having a first surface (1135) and a second surface (1136). The second lens (1132) may include an optically transparent member (1146) having a first surface (1137) and a second surface (1138). The second lens (1132) may be identical or similar to the second lens (132) described in Figure 1A. The optical system (110) may include a beam splitter (1141), a reflective polarizer (139), and a QWP (142) identical or similar to the beam splitter (141), reflective polarizer (139), and QWP (142) described in Figure 1A.

[0096] The eye relief (or distance D3) between region (151) and the first lens (1131) is 15 mm. The distance D4 (i.e., lens track length) between the display device (120) and the first lens (1131) is 12.5 mm. In one example, D1 is equal to the sum of D3 and D4. The display size indicated by the display image circle has a radius of 14.8 mm. The field of view (FOV) of the optical system (110) in Figure 11A is 100°.

[0097] The optically transparent member (1145) may be the same as or similar to the optically transparent member (145) described in Figure 1A. The first surface (1135) may have an aspherical shape similar to the first surface (135) described in Figures 1A and 1B.

[0098] Figures 12 and 13 show exemplary shapes of the first surface (1135) and second surface (1136) of the first lens (1131), and Figures 14 to 18 show the performance of the optical system (110) of Figure 11A using the first lens (1131) having the shapes shown in Figures 12 and 13 according to one embodiment of the present disclosure.

[0099] Figure 12 shows the relationship between the sag (in mm) of the second surface (1136) of the first lens (1131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). For clarity, the first lens (1131), region (151), and display device (120) are again depicted in Figure 11B. In one example, the sag shown in Figure 11B represents the distance along the optical axis (160) between line (1171) and each point on the curve (1136) formed by the intersection of the second surface (1136) of the first lens (1131) and the XY plane. Line (1171) passes through vertex V2 of the second surface (1136) and is tangential to the second surface (1136).

[0100] In one example, the diameter of the first lens (1131) (showing the portion of the first lens (1131) used) is the same as or similar to 46 mm. In Figure 12, (i) the minimum sagitta S at a first position (e.g., approximately 21 mm or -21 mm) of the second surface (1136) of the first lens (1131). min (ii) the maximum sagittal S at the second position (e.g., 0 mm) of the second surface (1136) of the first lens (1131) max The sag difference between the two is 1.5 mm to 2 mm. The sag at the edge of the second surface (1136) (e.g., 30 mm or -30 mm) is equal to the S at the first position. min Although smaller than, the edge of the second surface (1136) is not used for light beam transmission, so the sag at the edge of the second surface (1136) is S min It will not be used in the decision-making process.

[0101] Figure 13 shows the relationship between the sag (in mm) of the first surface (1135) of the first lens (1131) and its position along an axis perpendicular to the optical axis (160), e.g., the Y-axis. In one example, the sag in Figure 13 is the distance along the optical axis (160) between line (1172) and each point on the curve (1135) formed by the intersection of the first surface (1135) of the first lens (1131) and the XY plane. Line (1172) passes through the vertex V1 of the first surface (1135) and is tangential to the first surface (1135). In Figure 13, (i) the minimum sag S at a first position (e.g., approximately 18 mm or -18 mm) of the first surface (1135) of the first lens (1131). min (ii) the maximum sagittal S at the second position (e.g., 0 mm) of the first surface (1135) of the first lens (1131) max The sagittal difference between these two values ​​is between 1.5 millimeters (mm) and 2.5 mm.

[0102] Figures 14 to 17 show the MTF of the optical system (110) of Figure 11A, which uses a first lens (1131) having the shape shown in Figures 12 and 13. In Figure 14, the eye (60) is located in region (151), and the eye (60) is gazing straight ahead without rotation (e.g., field of view or eye rotation is 0°). Figure 14 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (1401) to (1403) represent the sagittal MTF for field of view angles from 0° to 50° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (1411) to (1413) represent the tangent MTF for field of view angles from 0° to 50° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0103] In Figure 15, eye (60) is located in region (151) and is gazing at a field of view of 10°. Figure 15 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (1501) to (1503) represent the sagittal MTF for field of view from 0° to 45° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (1511) to (1513) represent the tangent MTF for field of view from 0° to 45° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0104] In Figure 16, eye (60) is located in region (151) and is gazing at a field of view of 20°. Figure 16 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (1601) to (1603) represent the sagittal MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (1611) to (1613) represent the tangent MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0105] In Figure 17, eye (60) is located in region (151) and is gazing at a field of view of 30°. Figure 17 shows the sagittal MTF and tangent MTF against the field of view (e.g., Y field of view). Curves (1701) to (1703) represent the sagittal MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively. Curves (1711) to (1713) represent the tangent MTF for field of view from 0° to 40° at resolutions of 5 lp / mm, 10 lp / mm, and 20 lp / mm, respectively.

[0106] Referring again to Figures 14-17, the MTF can vary with resolution (e.g., 5, 10, or 20 lp / mm) and / or eye gazing angle. In particular, the MTF at a resolution of 20 lp / mm is greater than 80% at a 0° field of view and eye rotation to 0°, the MTF at a resolution of 20 lp / mm is greater than 40% at a 10° field of view and eye rotation to 10°, the MTF at a resolution of 20 lp / mm is greater than 25% at a 20° field of view and eye rotation to 20°, and the MTF at a resolution of 10 lp / mm is greater than 25% at a 30° field of view and eye rotation to 30°. Figures 14-17 show that the FOV can be 100° (e.g., from a -50° field of view to a 50° field of view) at a resolution of 10 lp / mm.

[0107] Figure 18 shows relative contrast for field of view angles from 0° to 50°. Across the entire FOV (e.g., 100°), the relative contrast is above 80% or 0.8.

[0108] By employing various shapes, including various waveform shapes, of the first surface (135) and / or second surface (136) of the first lens (131), similar performance characteristics such as a wide FOV, high resolution with low aberrations, and a compact form factor of the optical system (110) can be achieved. Figures 19 to 23 show exemplary shapes of the first surface (135) and / or second surface (136) of the first lens (131) according to embodiments of the present disclosure.

[0109] Referring to Figures 1B and 19, the vertex V2 of the second surface (136) of the first lens (131) is located at Z=0mm, the vertex V1 of the first surface (135) of the first lens (131) is located at Z=2.5mm, and the thickness of the center of the first lens (131) along the optical axis (160) is 2.5mm. Figure 19 shows the thickness profile (1901) of the first lens (131) showing the change in thickness (parallel to the Z axis) of the first lens (131) with respect to the position from the optical axis (160) (e.g., the Y coordinate parallel to the Y axis). The Y coordinates of vertices V1 and V2 are 0mm. The thickness profile (1901) shows that the change in thickness of the first lens (131) is similar to that described in Figure 1C.

[0110] Figure 19 further illustrates the relationship between the sag (1903) of the second surface (136) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the sag (1903) represents the relationship between the Y-coordinate and the Z-coordinate (Z-position) of the second surface (136). Furthermore, Figure 19 shows the position profile (1902) with respect to the position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the position profile (1902) represents the relationship between the Y-coordinate and the Z-coordinate of the first surface (135). In one example, the Z-coordinate of the first surface (135) may be the sum of (i) the sag of the first surface (135) of the first lens (131) as described in Figure 1B, and (ii) the thickness of the center of the first lens (131) (e.g., 2.5 mm). The position profile (1902) and sag (1903) indicate that the wavy shape of the first surface (135) and the second surface (136) shown in Figure 19 is similar to that described in Figures 1B and 1C.

[0111] In one example, a display system (100) using the lens system (130) shown in Figure 19 achieves the following parameters: the eye relief (or distance D3) between the area (151) and the first lens (1131) is 15 mm; the display size is indicated by a diagonal display size of 1.3 inches; and the FOV is 90°.

[0112] Referring to Figures 1B and 20, the vertex V2 of the second surface (136) of the first lens (131) is located at Z=0mm, the vertex V1 of the first surface (135) of the first lens (131) is located at Z=2.5mm, and the thickness of the center of the first lens (131) along the optical axis (160) is 2.5mm. Figure 20 shows the thickness profile (2001) of the first lens (131) showing the change in thickness (parallel to the Z axis) of the first lens (131) with respect to the position (e.g., Y coordinate) from the optical axis (160). The Y coordinates of vertices V1 and V2 are 0mm. The thickness profile (2001) shows that the change in thickness of the first lens (131) is similar to that described in Figure 1C. Referring to Figure 20, in one example, if the diameter of the first lens (131) is greater than the value (e.g., about 23 mm), the thickness near or at the edge of the first lens (131) may be greater than the thickness at the center of the first lens (131).

[0113] Figure 20 further illustrates the relationship between the sag (2003) of the second surface (136) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the sag (2003) represents the relationship between the Y-coordinate and the Z-coordinate of the second surface (136). Referring to Figure 20, in one example, if the diameter of the first lens (131) is greater than a value (e.g., approximately 23 mm), the sag near or at the edge of the first lens (131) is greater than 0. Furthermore, Figure 20 shows the position profile (2002) with respect to the position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the position profile (2002) represents the relationship between the Y-coordinate and the Z-coordinate of the first surface (135). In one example, the Z-coordinate of the first surface (135) may be the sum of (i) the sag of the first surface (135) of the first lens (131) as described in Figure 1B, and (ii) the thickness of the center of the first lens (131) (e.g., 2.5 mm). The position profile (2002) and sag (2003) indicate that the wavy shape of the first surface (135) and the second surface (136) shown in Figure 20 is similar to that described in Figures 1B and 1C.

[0114] In one example, a display system (100) using the lens system (130) shown in Figure 20 achieves the following parameters: the eye relief (or distance D3) between the area (151) and the first lens (1131) is 15 mm; the display size is indicated by a diagonal display size of 1.3 inches; and the FOV is 100°.

[0115] Referring to Figures 1B and 21, the vertex V2 of the second surface (136) of the first lens (131) is located at Z=0mm, the vertex V1 of the first surface (135) of the first lens (131) is located at Z=3mm, and the thickness of the center of the first lens (131) along the optical axis (160) is 3mm. Figure 21 shows the thickness profile (2101) of the first lens (131) showing the change in the thickness (parallel to the Z axis) of the first lens (131) with respect to the position (e.g., Y coordinate) from the optical axis (160). The Y coordinates of vertices V1 and V2 are 0mm. The thickness profile (2101) shows that the change in the thickness of the first lens (131) is similar to that described in Figure 1C.

[0116] Figure 21 further illustrates the relationship between the sag (2103) of the second surface (136) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the sag (2103) represents the relationship between the Y-coordinate and the Z-coordinate of the second surface (136). Referring to Figure 21, in one example, if the diameter of the first lens (131) is greater than a value (e.g., approximately 27 mm), the sag near or at the edge of the first lens (131) is greater than 0. Furthermore, Figure 21 shows the position profile (2102) with respect to the position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the position profile (2102) represents the relationship between the Y-coordinate and the Z-coordinate of the first surface (135). In one example, the Z-coordinate of the first surface (135) may be the sum of (i) the sag of the first surface (135) of the first lens (131) as described in Figure 1B, and (ii) the thickness of the center of the first lens (131) (e.g., 3 mm). The position profile (2102) and sag (2103) indicate that the wavy shape of the first surface (135) and the second surface (136) shown in Figure 21 is similar to that described in Figures 1B and 1C.

[0117] In one example, a display system (100) using the lens system (130) shown in Figure 21 achieves the following parameters: the eye relief (or distance D3) between the region (151) and the first lens (1131) is 15 mm; the distance D4 (i.e., lens track length) between the display device (120) and the first lens (1131) is 14.7 mm; the display size indicated by the display image circle has a radius of 17.1 mm; the FOV is 110°; in one example, the gap between the display device (120) and the beam splitter (141) is 1 mm; in one example, referring to Figure 1A, the gap (133) between the first lens (131) and the second lens (132) is, for example, 1.2 mm along the optical axis (160).

[0118] Referring to Figures 1B and 22, the vertex V2 of the second surface (136) of the first lens (131) is located at Z=0mm, the vertex V1 of the first surface (135) of the first lens (131) is located at Z=4mm, and the thickness of the center of the first lens (131) along the optical axis (160) is 3mm. Figure 22 shows the thickness profile (2201) of the first lens (131) showing the change in thickness (parallel to the Z axis) of the first lens (131) with respect to the position (e.g., Y coordinate) from the optical axis (160). The Y coordinates of vertices V1 and V2 are 0mm. The thickness profile (2201) shows that the change in thickness of the first lens (131) is similar to that described in Figure 1C.

[0119] Figure 22 further illustrates the relationship between the sag (2203) of the second surface (136) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the sag (2203) represents the relationship between the Y-coordinate and the Z-coordinate of the second surface (136). Referring to Figure 22, in one example, if the diameter of the first lens (131) is greater than a value (e.g., approximately 28 mm), the sag near or at the edge of the first lens (131) is greater than 0. Furthermore, Figure 22 shows the position profile (2202) with respect to the position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the position profile (2202) represents the relationship between the Y-coordinate and the Z-coordinate of the first surface (135). In one example, the Z-coordinate of the first surface (135) may be the sum of (i) the sag of the first surface (135) of the first lens (131) as described in Figure 1B, and (ii) the thickness of the center of the first lens (131) (e.g., 4 mm). The position profile (2202) and sag (2203) indicate that the wavy shape of the first surface (135) and the second surface (136) shown in Figure 21 is similar to that described in Figures 1B and 1C.

[0120] In one example, a display system (100) using the lens system (130) shown in Figure 22 achieves the following parameters: the eye relief (or distance D3) between the region (151) and the first lens (1131) is 15 mm; the distance D4 (i.e., lens track length) between the display device (120) and the first lens (1131) is 16.1 mm; the display size indicated by the display image circle has a radius of 18.9 mm; the FOV is 110°; in one example, the gap between the display device (120) and the beam splitter (141) is 1.5 mm; in one example, referring to Figure 1A, the gap (133) between the first lens (131) and the second lens (132) is, for example, 2.1 mm along the optical axis (160).

[0121] Referring to Figures 1B and 23, the vertex V2 of the second surface (136) of the first lens (131) is located at Z=0mm, the vertex V1 of the first surface (135) of the first lens (131) is located at Z=4mm, and the thickness of the center of the first lens (131) along the optical axis (160) is 3mm. Figure 23 shows the thickness profile (2301) of the first lens (131) showing the change in the thickness (parallel to the Z axis) of the first lens (131) with respect to the position (e.g., Y coordinate) from the optical axis (160). The Y coordinates of vertices V1 and V2 are 0mm. The thickness profile (2301) shows that the change in the thickness of the first lens (131) is similar to that described in Figure 1C.

[0122] Figure 23 further illustrates the relationship between the sag (2303) of the second surface (136) of the first lens (131) and its position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the sag (2303) represents the relationship between the Y-coordinate and the Z-coordinate of the second surface (136). Furthermore, Figure 23 shows a position profile (2302) with respect to the position along an axis perpendicular to the optical axis (160) (e.g., the Y-axis). In one example, the position profile (2302) represents the relationship between the Y-coordinate and the Z-coordinate of the first surface (135). In one example, the Z-coordinate of the first surface (135) may be the sum of (i) the sag of the first surface (135) of the first lens (131) as described in Figure 1B, and (ii) the thickness of the center of the first lens (131) (e.g., 4 mm). The positional profile (2302) and sag (2303) indicate that the wavy shape of the first surface (135) and the second surface (136) shown in Figure 23 is similar to that described in Figures 1B and 1C.

[0123] Referring to Figures 19 to 23, each thickness profile has three maximum thicknesses, for example, a central thickness and an edge or peripheral region thickness. Each thickness profile also has two minimum thicknesses, each of which lies between the central thickness and one of the edge thicknesses.

[0124] In one example, a display system (100) using the lens system (130) shown in Figure 23 achieves the following parameters: the eye relief (or distance D3) between the region (151) and the first lens (1131) is 15 mm; the distance D4 (i.e., lens track length) between the display device (120) and the first lens (1131) is 20.3 mm; the display size indicated by the display image circle has a radius of 23 mm; the FOV is 110°; in one example, the gap between the display device (120) and the beam splitter (141) is 5.8 mm; in one example, referring to Figure 1A, the gap (133) between the first lens (131) and the second lens (132) is, for example, 3 mm along the optical axis (160).

[0125] The wavy shape of a lens surface can be described using various examples. In one example, the wavy shape includes an inner surface that curves toward one direction (e.g., convex) and an outer surface that curves toward the opposite direction (e.g., concave), as shown in Figure 1B, with the inner surface surrounded by the outer surface. In another example, the wavy shape includes a concave inner surface and a convex outer surface, with the inner surface surrounded by the outer surface. In yet another example, the curve formed by the intersection of the wavy surface of the lens and a cross-sectional plane (parallel to the optical axis of the lens) has at least four inflection points, as shown in Figure 1B, for example. In yet another example, a plane perpendicular to the optical axis of the lens (e.g., the XY plane) intersects the lens surface at least four times, as shown in Figure 1B, for example. In yet another example, the thickness of the central region of the lens decreases from the center of the lens, and the thickness of the peripheral region of the lens increases from the boundary of the central region. In one example, the wavy shape of the surface is indicated by the relationship between the surface sag and its position along an axis perpendicular to the optical axis (e.g., the Y-axis). For example, in Figure 5, the sag oscillates multiple times with respect to its position along the Y-axis, illustrating the wavy shape of the first surface (135).

[0126] The display system (100) may have any suitable parameters such as FOV, lens track length, eye relief, diameter of the first lens (131) or (1131) and the second lens (132) or (1132), gap between the display device (120) and the lens system (130) or (1300) (e.g., gap between the display device (120) and the beam splitter (141)), gap (133) between the first lens (131) and the second lens (132), display size, and area (151) size. Specific parameters of the display system (100) may be relevant. For example, the diameters of the first lens (131) or (1131) and the second lens (132) or (1132) may be selected based on other parameters of the display system (100), such as eye relief and FOV. In one example, if the field of view (FOV) of the display system (100) is 90° or more with an eye relief of 15 mm, the diameters of the first lens (131) or (1131) and the second lens (132) or (1132) are 46 mm or more.

[0127] In one embodiment, the display system (100) is used as an NED system, and the display system (100) using the optical system (110) can be configured to have a lens track length of less than or within a specific range (e.g., 12 mm to 20 mm) and an eye relief of less than or within a specific range (e.g., 15 mm). In one example, the diameters of the first lens (131) or (1131) and the second lens (132) or (1132) are 46 mm or more or within a specific range. The gap between the display device (120) and the lens system (130) or (1300) (e.g., the gap between the display device (120) and the beam splitter (141)) may vary, for example, from 1 to 6 mm. The gap (133) between the first lens (131) and the second lens (132) may vary, for example, from 1 to 3 mm. The FOV of the display system (100) may be 90° or more. The display size may be larger than a radius of 14 mm. In one example, the size of area (151) is configured to be 5 mm (e.g., a 5 mm pupil size for eye (60)) to accommodate variations in pupil size for different people under different lighting conditions. For example, an adult's pupil size can vary from 2 to 4 mm in diameter in bright light to 4 to 8 mm in dim light.

[0128] In one example, the eye relief is 15 mm, the center thickness of the first lens (131) is 3 mm, the gap (133) between the first lens (131) and the second lens (132) is 2 mm, and the edge thickness of the second lens (132) (e.g., the maximum thickness of the second lens (132)) is 3 mm. In one example, the diameter of the first lens (131) or (1131) and the second lens (132) or (1132) is 46 mm when the FOV of the display system (100) is 90°. In one example, the diameter of the first lens (131) or (1131) and the second lens (132) or (1132) is 34 mm with an eye relief of 10 mm.

[0129] Embodiments of this disclosure describe a display system (100) including a lens having at least one corrugated surface (e.g., the first surface (135) of the first lens (131)) as shown in Figures 1A to 1D, Figure 4, Figure 5, and Figures 19 to 23. The lens having at least one corrugated surface can be used together with other lenses, such as a second lens (132). Furthermore, the lens having at least one corrugated surface can be used together with a plurality of lenses, such as two lenses or three lenses. In one example, a plurality of lenses, each having at least one corrugated surface, can be employed in the display system (100). The at least one corrugated surface may be the same as or identical to the first surface (135) described in this disclosure.

[0130] Referring again to Figure 1A, the shift block (170) is connected to the optical system (110) and applies appropriate spatial pixel shift adjustment to the virtual image 199. The controller (180) is connected to the optical system (110) and the shift block (170) and controls the operation of the optical system (110) and the shift block (170).

[0131] The shift block (170) can apply spatial pixel shift adjustment mechanically or optically. The shift block (170) may include a mechanical shifter for applying spatial pixel shift adjustment. In some examples, the mechanical shifter can shift the display device (120) to apply spatial pixel shift adjustment. In some examples, the mechanical shifter can shift at least one optical element (e.g., a first lens (131) or a second lens (132) in a lens system (130)) to apply spatial pixel shift adjustment. Relatively small adjustments to the gap (133) can be amplified, for example, by a factor of three due to the aliasing path (125) in the optical resonator.

[0132] The display system (100) may include other suitable mechanical, electrical, and optical components. For example, the display system (100) may include a frame (101) that can protect other components of the display system (100). In another example, the display system (100) may include a strap (not shown) for fitting the display system (100) to the user's head. In yet another example, the display system (100) may include communication components (not shown, e.g., communication software and hardware) for wireless communication with a network, a host device, and / or other devices. In some examples, the display system (100) may include an optical combiner that can combine virtual content with a see-through reality environment.

[0133] The embodiments of this disclosure may be used separately or combined in any order.

[0134] A computer or computer-readable medium can control various embodiments of an HMD system incorporating a display system (100) including an optical system (110). Various embodiments of the display system (100), including control of the movement and positioning of optical components (e.g., a first lens (131), a second lens (132), a display device (120)), can be implemented as computer software using computer-readable instructions and can be physically stored on one or more computer-readable media. For example, Figure 24 shows a computer system (2400) suitable for implementing a particular embodiment of the subject matter of this disclosure.

[0135] Computer software can be coded using any suitable machine code or computer language that can be subjected to mechanisms such as assembly, compilation, and linking in order to generate code that includes instructions that can be executed directly by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., or through interpretation, microcode execution, etc.

[0136] Instructions can be executed on various types of computers or their components, including, for example, personal computers, tablet computers, servers, smartphones, gaming devices, and Internet of Things devices.

[0137] The components shown in Figure 24 of the computer system (2400) are illustrative in nature and are not intended to imply any limitation on the scope of use or functionality of computer software implementing embodiments of the present disclosure. Furthermore, the configuration of the components should not be construed as having any dependency or necessity with respect to any component or combination of components shown in the exemplary embodiment of the computer system (2400).

[0138] The computer system (2400) may include certain human interface input devices. Such human interface input devices may respond to input from one or more human users, for example, through tactile input (e.g., keystrokes, swipes, data glove movements), voice input (e.g., voice, clapping), visual input (e.g., gestures), or olfactory input (not shown). Human interface devices may also be used to capture certain media that are not necessarily directly related to conscious human input, such as audio (e.g., voices, music, ambient sounds), images (e.g., scanned images, photographic images obtained from still cameras), or video (e.g., two-dimensional images, three-dimensional images including stereoscopic images).

[0139] Input human interface devices may include one or more of the following (only one of each is illustrated): keyboard (2401), mouse (2402), trackpad (2403), touchscreen (2410), data glove (not shown), joystick (2405), microphone (2406), scanner (2407), and camera (2408).

[0140] Furthermore, the computer system (2400) may also include certain human interface output devices. Such human interface output devices can stimulate the senses of one or more human users, for example, through tactile output, sound, light, and smell / taste. Examples of such human interface output devices include tactile output devices (e.g., tactile feedback via a touchscreen (2410), data glove (not shown), or joystick (2405), although tactile feedback devices that do not function as input devices may also exist), audio output devices (e.g., speakers (2409), headphones (not shown)), visual output devices (e.g., touchscreens (2410) including CRT screens, LCD screens, plasma screens, and OLED screens, each of which may or may not have a touchscreen input function, each of which may or may not have a tactile feedback function, and some of which may be capable of outputting two-dimensional visual output, or outputting more than three dimensions via means such as stereographic output, virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown).

[0141] Furthermore, the computer system (2400) may include human-accessible storage devices and their associated media, such as optical media including CD / DVD ROM / RW (2420) with media such as CD / DVD (2421), thumb drives (2422), removable hard drives or solid-state drives (2423), legacy magnetic media such as tapes and floppy disks (not shown), and devices based on dedicated ROM / ASIC / PLD such as security dongles (not shown).

[0142] Furthermore, those skilled in the art should understand that the term “computer-readable medium” as used in relation to the subject matter of this disclosure does not include transmission media, carrier waves, or other transient signals.

[0143] Furthermore, the computer system (2400) may include an interface (2454) to one or more communication networks (2455). The networks may be, for example, wireless, wired, or optical. Additionally, the networks may be local, wide-area, metropolitan, vehicle and industrial, real-time, latency-tolerant, etc. Examples of networks include local area networks such as Ethernet and Wi-Fi; cellular networks including GSM, 3G, 4G, 5G, LTE, etc.; wired or wireless wide-area digital TV networks including cable TV, satellite TV, and terrestrial broadcast TV; and vehicle and industrial networks including CANBus. Certain networks generally require an external network interface adapter attached to a specific general-purpose data port or peripheral bus (2449) (e.g., a USB port on the computer system (2400)), while others are generally integrated into the core of the computer system (2400) by attachment to a system bus as described below (e.g., an Ethernet interface to a PC computer system, or a cellular network interface to a smartphone computer system). Using any of these networks, the computer system (2400) can communicate with other entities. Such communication may be unidirectional (e.g., broadcast TV), unidirectional (e.g., CANbus to a specific CANbus device), or bidirectional, for example, to other computer systems using local or wide-area digital networks. Specific protocols and protocol stacks may be used for each of the networks and network interfaces described above.

[0144] The aforementioned human interface devices, human-accessible storage devices, and network interfaces can be attached to the core (2440) of the computer system (2400).

[0145] The core (2440) may include one or more central processing units (CPUs) (2441), graphics processing units (GPUs) (2442), dedicated programmable processing units in the form of field-programmable gate areas (FPGAs) (2443), hardware accelerators for specific tasks (2444), graphics adapters (2450), etc. These devices may be connected via a system bus (2448) along with read-only memory (ROM) (2445), random-access memory (2446), internal mass storage devices such as internal non-user-accessible hard drives (2447), SSDs, etc. In some computer systems, the system bus (2448) may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, etc. Peripherals can be connected directly to the core's system bus (2448) or via a peripheral bus (2449). In one example, a touchscreen (2410) can be connected to the graphics adapter (2450). Examples of peripheral bus architectures include PCI and USB.

[0146] The CPU (2441), GPU (2442), FPGA (2443), and accelerator (2444) can execute specific instructions that, in combination, constitute the aforementioned computer code. This computer code can be stored in ROM (2445) or RAM (2446). Transient data can also be stored in RAM (2446), while persistent data can be stored, for example, in internal mass storage (2447). High-speed storage and retrieval of any memory device can be made possible by using cache memory, which can be closely associated with one or more CPUs (2441), GPUs (2442), mass storage (2447), ROMs (2445), RAM (2446), etc.

[0147] A computer-readable medium may contain computer code for performing various computer implementation operations. The medium and computer code may be specifically designed and constructed for the purposes of this disclosure, or they may be of a type well known and available to those skilled in the computer software technology.

[0148] For example, but not limited to, a computer system (2400) having an architecture, in particular a core (2440), can provide functionality as a result of the execution of software embodied in one or more tangible computer-readable media by a processor (including a CPU, GPU, FPGA, accelerator, etc.). Such computer-readable media may be mass storage accessible to the user as described above, as well as media associated with specific storage of the core (2440) of a non-transient nature, such as intracore storage (2447) or ROM (2445). Software implementing various embodiments of the present disclosure may be stored in such devices and executed by the core (2440). The computer-readable media may include one or more memory devices or chips, depending on the specific needs. The software may cause the core (2440), specifically the processor (including a CPU, GPU, FPGA, etc.) therein, to execute certain processes or specific parts of certain processes described herein, such as defining data structures stored in RAM (2446) and modifying such data structures according to processes defined by the software. In addition to or instead of software, a computer system may provide functionality as a result of logic embodied in hardwired or other circuits (e.g., accelerators (2444)) that can perform, in place of or in conjunction with software, certain processes or certain parts of certain processes described herein. References to software may, as necessary, include logic, and vice versa. References to computer-readable media may, as necessary, include circuits that store software for execution (such as integrated circuits (ICs)), circuits that embody logic for execution, or both. This disclosure encompasses any suitable combination of hardware and software.

[0149] While this disclosure has described several exemplary embodiments, there are many variations, substitutions, and alternative equivalents that fall within the scope of this disclosure. Therefore, those skilled in the art will understand that numerous systems and methods, not expressly illustrated or described herein, can be conceived that embody the ideas of this disclosure and thus fall within its spirit and scope.

Claims

1. An optically transparent member having a first surface and a second surface, wherein the optically transparent member is configured to receive light from a display device through the first surface, and the received light exits the optically transparent member through the second surface, The first surface and the second surface of the optically transparent member are aspherical. The inner surface of the first surface is convex, A first lens, wherein the outer surface of the first surface is concave, and the inner surface is surrounded by the outer surface of the first surface.

2. The curve formed by the intersection of the first surface of the first lens and the cross-sectional plane has at least four inflection points, and the cross-sectional plane is parallel to the optical axis of the first lens. The first lens according to claim 1.

3. A plane perpendicular to the optical axis of the first lens intersects the second surface of the first lens four times. The first lens according to claim 1.

4. (i) The sajitter difference between the minimum sajitter at a first position on the first surface of the first lens and (ii) the maximum sajitter at a second position on the first surface of the first lens is between 1.5 millimeters (mm) and 2.5 mm. The first lens according to claim 1.

5. (i) The sagittal difference between the minimum sagittal at a first position on the second surface of the first lens and (ii) the maximum sagittal at a second position on the second surface of the first lens is between 0.6 mm and 0.8 mm. The first lens according to claim 4.

6. The first lens according to claim 1, A second lens configured to direct light from the display device towards the first lens, wherein the first lens is located between the second lens and the light receiving unit, and the second lens is a light-gathering lens. A lens system equipped with these features.

7. The first lens and the second lens are separated by a gap. The lens system according to claim 6.

8. The lens system described in claim 6, A beam splitter configured to partially transmit and partially reflect the light beam from the display device, A reflective polarizer configured to allow light in a first linearly polarized state to pass through and to reflect light in a second linearly polarized state perpendicular to the first linearly polarized state, A quarter-wave plate (QWP) is placed between the beam splitter and the reflective polarizer. Equipped with, The optical axis of the first lens and the optical axis of the second lens are the same within the lens system. The beam splitter is located on the first surface of the second lens, which is configured to face the display device. The reflective polarizer is located on the second surface of the first lens, forming an optical system.

9. The QWP is located on (i) the surface of the first lens or (ii) the surface of the second lens. The optical system according to claim 8.

10. The optical system includes the display device, the pixel array in the display device is configured to generate a light beam, and the polarization state of the light beam is a first circularly polarized state. An optical resonator is formed between the beam splitter and the reflective polarizer. The optical resonator includes the first lens, the second lens, the gap between the first lens and the second lens, and the QWP. The beam splitter partially transmits one of the light beams, After one of the light beams has passed through the optical resonator for the first time, the first circularly polarized state of the one of the light beams is converted to the second linearly polarized state by the QWP. The reflective polarizer reflects one of the light beams in the second linearly polarized state, After one of the light beams has passed through the optical resonator for the second time, the other light beam is reflected by the beam splitter. After one of the light beams has passed through the optical resonator for the third time, the second linearly polarized state of the one of the light beams is converted to the first linearly polarized state by the QWP. The reflective polarizer transmits one of the light beams in the first linearly polarized state such that the one of the light beams is directed toward the light receiving section. The optical system according to claim 8.

11. The aforementioned optical system is included in a head-mounted display (HMD). The field of view of the optical system is 90° or more, the distance between the light-receiving unit and the first lens is 15 ± 2 millimeters (mm), the lens track length, which is the distance between the second lens and the display device, is 12 to 21 mm, and the diagonal size of the area of ​​the display device that generates the light beam is 1.4 inches to 2.6 inches. The optical system according to claim 10.

12. An optically transparent member having a first surface and a second surface, wherein the optically transparent member is configured to receive light from a display device through the first surface, and the received light exits the optically transparent member through the second surface, The first surface and the second surface of the optically transparent member are aspherical. The thickness of the central region of the first lens decreases from the center of the first lens. The thickness of the peripheral region of the first lens increases from the boundary of the central region.

13. The curve formed by the intersection of the first surface of the first lens and the cross-sectional plane has at least four inflection points, and the cross-sectional plane is parallel to the optical axis of the first lens. The first lens according to claim 12.

14. A plane perpendicular to the optical axis of the first lens intersects the second surface of the first lens four times. The first lens according to claim 12.

15. (i) The sajitter difference between the minimum sajitter at a first position on the first surface of the first lens and (ii) the maximum sajitter at a second position on the first surface of the first lens is between 1.5 millimeters (mm) and 2.5 mm. The first lens according to claim 12.

16. (i) The sagittal difference between the minimum sagittal at a first position on the second surface of the first lens and (ii) the maximum sagittal at a second position on the second surface of the first lens is between 0.6 mm and 0.8 mm. The first lens according to claim 15.

17. The first lens according to claim 12, A second lens configured to direct light from the display device towards the first lens, wherein the first lens is located between the second lens and the light receiving unit, and the second lens is a light-gathering lens. A lens system equipped with these features.

18. The first lens and the second lens are separated by a gap. The lens system according to claim 17.

19. The lens system described in claim 17, A beam splitter configured to partially transmit and partially reflect the light beam from the display device, A reflective polarizer configured to allow light in a first linearly polarized state to pass through and to reflect light in a second linearly polarized state perpendicular to the first linearly polarized state, A quarter-wave plate (QWP) is placed between the beam splitter and the reflective polarizer. Equipped with, The optical axis of the first lens and the optical axis of the second lens are the same within the lens system. The beam splitter is located on the first surface of the second lens, which is configured to face the display device. The reflective polarizer is located on the second surface of the first lens, forming an optical system.

20. The aforementioned optical system is included in a head-mounted display (HMD). The field of view of the optical system is 90° or more, the distance between the light-receiving unit and the first lens is 15 ± 2 millimeters (mm), the lens track length, which is the distance between the second lens and the display device, is 12 to 21 mm, and the diagonal size of the area of ​​the display device that generates the light beam is 1.4 inches to 2.6 inches. The optical system according to claim 19.

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