Optical Device and Method

Abstract

An optical device made according to an augmented reality optical design, the optical device comprising a plurality of optical elements for transmitting light from a light source for display to a user's eye, the optical device comprising a light source that generates light, a lens assembly that is off-axis from the light source and is configured to receive the light, and a combiner that receives the light from the lens assembly via one or more additional optical elements of the plurality of optical elements and guides the light to form a virtual image at an exit pupil at the position of the eye, the combiner comprising a first inner optical surface form and a second outer optical surface form, the first inner optical surface form and the second outer optical surface form being different in order to minimize the deviation in an outer view from the combiner.

Description

Technical Field

[0001] The present invention relates to optical devices and methods.

Background Art

[0002] Augmented reality optical devices are well known and are intended to provide real-world and virtual images that are superimposed when presented to a user. Many augmented reality optical devices are intended to be worn by a user, for example, in a head worn device (HWD), a head mounted display (HMD), or a helmet. To avoid causing physical discomfort to the user, it is useful if the wearable device is lightweight and small. This is not always the case.

[0003] As a result, there is a need for improved small and lightweight optical devices for use in augmented reality optical designs.

Summary of the Invention

[0004] According to one aspect of the present invention, there is provided an optical device made according to an augmented reality optical design, the optical device comprising a plurality of optical elements for transmitting light from a light source for display to a user's eye, the optical device comprising a light source for generating light, a lens assembly that is off-axis from the light source and configured to receive the light, and a combiner that receives the light from the lens assembly via one or more additional optical elements of the plurality of optical elements and guides the light to form a virtual image at an exit pupil at the position of the eye, the combiner comprising a first inner optical surface form and a second outer optical surface form, the first inner optical surface form and the second outer optical surface form being different to minimize a shift in an outer view from the combiner.

[0005] In one aspect, the combiner is aspherical.

[0006] In one aspect, the combiner is tilted about at least the first axis.

[0007] In one aspect, the combiner is off-axis with respect to the straight optical path.

[0008] In one aspect, the combiner includes an optical coating over at least the optically active region of the combiner.

[0009] In one aspect, the combiner is made of a plastic material with a coating.

[0010] In one aspect, the coating is configured to provide different functionalities.

[0011] In one aspect, the combiner includes one of a holographic optical element, a diffractive optical element, and an optical microstructure.

[0012] In one aspect, the combiner has a variable thickness across the area of the combiner.

[0013] In one aspect, the first inner optical surface form and the second outer optical surface form are bi-cones.

[0014] In one aspect, the first inner optical surface form and the second outer optical surface form are described by a multi-degree polynomial function.

[0015] In one aspect, the first inner optical surface form and the second outer optical surface form each have different radii of curvature along the X-axis and the Y-axis and are not coaxial.

[0016] In one aspect, the first inner optical surface form and the second outer optical surface form each have different conic constants along the X-axis and the Y-axis.

[0017] In one aspect, one or more additional optical elements among the plurality of optical elements include a first at least partially mirrored device and a second optical device disposed substantially orthogonally to the first at least partially mirrored device and positioned intermediate the lens assembly and the first at least partially mirrored device, the second optical device being configured to receive light from the lens assembly and transmit the light to the first at least partially mirrored device.

[0018] In one aspect, the light source is a radiation source including a plurality of self-emitting pixels.

[0019] In one aspect, each pixel is adapted for illumination and radiation over a wide cone angle.

[0020] In one aspect, each pixel has a cone angle greater than + / - 25 degrees.

[0021] In one aspect, the optical device is arranged to fold the optical path about a first axis (XYZ) and a second axis (XYZ).

[0022] In one aspect, forms part of a wearable device and at least a portion of the optical device is folded above or to the side of the user's eyebrow.

[0023] In one aspect, the lens assembly is a relay lens assembly.

[0024] According to one aspect of the present invention, a binocular optical device is provided comprising two optical devices according to another aspect.

[0025] According to one aspect of the present invention, a wearable device is provided comprising one or two optical devices according to another aspect.

[0026] According to one aspect of the present invention, there is provided a system comprising a plurality of processors configured to transmit and receive data and process the data, one or more sensors configured to collect at least a part of the data from the environment and transmit the data to the processors, and one or more wearable devices according to another aspect.

[0027] According to one aspect of the present invention, there is provided a method of guiding light through an optical device made according to an extended reality optical design, the optical device comprising a plurality of optical elements for transmitting light from a light source for display to a user's eye, the method comprising emitting light through the light source, guiding the light towards a combiner 408 through one or more additional optical devices, and guiding the light through the combiner to form a virtual image at an exit pupil of the optical device, the combiner comprising a first inner optical surface form and a second outer optical surface form, the first inner optical surface form and the second outer optical surface form being different to minimize a shift in an outer view from the combiner.

[0028] In one aspect, the method further comprises the combiner being aspherical, the combiner being tiltable about at least a first axis, the combiner being off-axis with respect to a direct optical path, the combiner including an optical coating over at least an optically active region of the combiner, the combiner being made of a plastic material, and the combiner including at least one of a holographic optical element, a diffractive optical element, and an optical microstructure.

[0029] Next, embodiments of the present invention will be described merely by way of example with reference to the drawings.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0031] The present invention relates to an augmented reality optical design for providing real-world images and virtual images that are superimposed when presented to a user. The augmented reality optical design is also referred to as an optical device designed according to the augmented reality optical design. The optical device is part of an optical system used in many different contexts to provide information to a user. In some cases, this is to display information to the pilot of a vehicle such as an aircraft.

[0032] Generally, such systems are designed to utilize emissive displays. Emissive displays typically have a wide emission cone angle. This can present problems if the total amount of light emitted by the display is not accurately controlled. FIG. 1 shows an ideal emission 100 and two non-ideal emissions 102 and 103. Light emitted by the display source outside the cone angle required by the optical system to meet the exit pupil requirements travels through the system and can either degrade one or more display parameters (e.g., contrast) or travel towards the eye. This light can then, if visible to the user, result in a region of the exit pupil where the display is inadequately corrected (e.g., blurry) but still visible (scenario 102). Scenario 103 shows how a physical aperture 104 can be used to limit visible light, as will be described in more detail below with respect to the present invention. Note that the aperture 104 can alternatively be located inside the optical system (i.e., not in front of the eye), such as an optical stop in a conventional optical projection system.

[0033] FIG. 2 is a schematic diagram of a folded linear structure. A known linear system is modified so that the eye 200 can view an image through the use of a coupling mirror 204. An aperture position 206 inside the lens system 208 is required to prevent the eye from being able to view uncorrected light 210. This results in an actual emission that is viewed through the mirror and controlled by the internal aperture position 206.

[0034] Conventionally, the aperture has been an absorption plate with a notch. These are undesirable as they limit the layout flexibility and require either additional mechanical components or a more complex housing design.

[0035] In the present invention shown in FIG. 3, the aperture is defined in a different manner and overcomes the problems of conventional apertures in augmented reality optical designs.

[0036] As shown in FIG. 3, the present invention includes an aperture that is the aperture 300 of the mirror base. Only the light rays that hit the mirror 300 are on the correct optical path that travels towards the eye 200. Thus, the shape and / or size of the mirror 300 has a direct correlation with the shape and / or size of the exit pupil generated by the system, and thus the light that travels to the exit pupil can be constrained thereby. The system further includes a singlet lens (for simplicity), but can include more complex arrangements. By using the aperture of the mirror base, the light rays passing through the system can be narrowed, but the system is simultaneously folded back to provide improved flexibility, space savings, and other related improvements. The light narrowed by the mirror is optionally filtered (dotted line) 310 in order to enable additional control over the bandwidth of the optical light propagating through the system.

[0037] The mirror 300 is positioned at or near the optical aperture of the system, and thus the light beam over the entire field of view of the system is incident over a well-defined small area. The mirror 300 is configured to be used to perform additional optical functions such as filtering or dimming of the incident light by a deformable form of its design. This can involve the use of different optical coatings, materials, etc. A similar function can be achieved by placing a conventional filter on top of a conventional transmissive optical aperture plate, but this also increases the number of components, which is undesirable. Further, a conventional filter needs to either absorb or reflect the filtered light, which presents a risk that the filtered light is reflected or scattered back into the lens arrangement. However, with the mirror arrangement of FIG. 3, the light that is not reflected by the mirror is transmitted to the back of the mirror and absorbed. There is no stray light illumination and spurious light is avoided.

[0038] A further advantage of the addition of the partially transmissive mirror is that a portion of the light from the lens arrangement transmitted by the mirror can be collected by an auxiliary small lens system arranged behind the mirror, such as a camera lens system and a sensor arranged to monitor the display content for monitoring purposes. A further advantage is that additional light can be injected into the optical system from behind the mirror, such as IR illumination for the purpose of gaze tracking, or an additional / secondary display lens arrangement for providing additional optical functionality.

[0039] The basic concepts described above are further developed and provide further advantages as described with reference to FIGS. 4 and 5. As described above, the radiographic image source (e.g., an optical device) according to the present invention has a wide radiation cone angle. The radiographic image source 424 includes a plurality of self-radiating pixels. Each pixel can illuminate and radiate light over a wide cone angle. The cone angle is greater than about + / -25 degrees and up to about + / -90 degrees. However, as will be described in more detail below, the optical device of the present invention compensates for the problem of stray light in the optical device that typically causes degradation of display content such as lower contrast or secondary images. In the present application, the image source is also referred to as a light source and generates light that passes through the optical device and forms an image when it reaches the user's pupil. In addition, the light source can vary for different situations in order to cover optical and non-optical wavelengths.

[0040] In the first case of FIG. 4, light is directed towards the eye 400 by the optical device 402. The optical device 402 includes a relay lens or lens assembly 404, a first element 406, and a combiner element 408. The approximate position of the second element is shown as 410. In FIG. 5, a second element 412 is shown. The first element 406 and the second element 412 are mirrors in one example. In the figure, the X-axis crosses the eye, the Y-axis points outward from the head, and the Z-axis points from above the head downwards.

[0041] In FIG. 5, the device is deployed around the position 410 of the second mirror, and secondly, with the second mirror 412 inserted, the device is further folded in-plane with respect to the drawing. The second mirror 412 is rotated about the Y-axis, which is not shown in the sketch as it is a 2D projection for clarity. The mirror can be rotated about the X-axis or the Y-axis, adding flexibility to the folding arrangement, for example, allowing the system to be folded upward or to the side of the brow. It is optimal to position the second mirror 412 near or ideally around the aperture of the device. The device includes an appropriate aperture and folds the relay lens at an angle that envelops the typical shape of the head (as shown in FIGS. 8 and 9). In some cases, the second mirror is a light device that is partially transmissive in order to filter out unwanted light or transmit it onto an absorption region. The light device enables light to be directed to at least a partially reflective surface of the first mirror device. The figure shows a single ray from the theoretical exit pupil position for three nominal sets of field angles. It will be understood that a wider exit pupil area provides multiple field angles (i.e., the coverage of the lens and / or mirror by the rays is larger than that shown).

[0042] The optical device is arranged such that an optical path is defined with two folds. The first fold is at the second mirror and the second fold is at the first mirror. This arrangement ensures a compact device, as also shown in FIG. 7. As a result of the two folds, the entire optical device includes parts in an arrangement that can be supported on the side of the head when in use. This contributes to the comfort and weight of the device, since the housing of the device is smaller and lighter. It makes the optical device more practical to wear. In addition, the view through the combiner is not interfered with by a bulky or visible device. This can be achieved by tilting the combiner, i.e., tilting the combiner with respect to a horizontal axis. Such a tilted eyepiece, if sufficiently far from the user's face, can allow space for the user to wear personal eyewear, such as glasses for vision correction. This embodiment provides a combiner eye relief (i.e., a suitable distance from the eye to the combiner) of 53.5 mm. However, in alternative embodiments, a range of 48 to 59 mm is contemplated.

[0043] The combiner defines a plane that is generally parallel to the plane defined by the first mirror. The axis defined by these planes is generally parallel to the Y axis. Such a provision can further aid in a compact form factor and free up space in the area corresponding to the bridge of the user's nose.

[0044] The combiner element 408 has an aspherical surface profile that is tilted about at least a first axis, in this case the X axis. This surface profile is also eccentric about the Y axis, i.e., the central ray within the FOV does not strike the center of the optical surface profile. The combiner is arranged to redirect one or more wavelengths towards the user so that the user can simultaneously view the virtual display generated by the light device and the external world 414. The combiner 408 is arranged to redirect the light incident therethrough by use of an optical coating applied on at least a portion of the surface of the combiner. The coating is preferably applied over the entire surface, or alternatively, only the "optically active" region of the combiner, e.g., only where the light rays are likely to strike the combiner and not elsewhere, may be coated. The aspherical shape is used to help compensate for off-axis aberrations. Since the combiner is tilted, it induces optical aberrations in the image light.

[0045] The aberrations are caused particularly because the combiner is off-axis with respect to the straight path of the light, and these aberrations can include spherical aberration, coma aberration, astigmatism, and distortion. The combiner is tilted to redirect the light accurately, and if the combiner is not tilted accurately, the light will not be sent towards the eye. Using only a spherical surface profile limits the degrees of freedom for optical correction in the design, allowing the combiner to have a more complex surface profile, e.g., a bi-conic surface, and thus allowing additional degrees of freedom for better correcting the aberrations caused by the tilting of the element.

[0046] The use of the bi-conic surface profile has many advantages. Different radii in both the X and Y axes allow for different optical powers in both axes and also allow for the introduction of conic contributions in both the X and Y axes. The conic contribution changes the spherical shape to an alternative surface profile that is more eccentric with respect to the shape and, depending on the value of the conic contribution, such as an ellipse, hyperbola, or parabola, helps to compress the light beam of the reflected light into a smaller beam compared to a typical spherical surface profile.

[0047] The combiner includes a first optical surface form on its inner surface 416 and a different second optical surface form on its outer surface 418 to minimize deviation to the external view 414. The surface form on the outer surface 418 is described by a different set of optical parameters from the inner surface 416. The outer surface 418 is generally not coaxial with the inner surface 416, and the thickness between the two surfaces varies across the area of the combiner 408. The surface forms are generally described by different radii and conic constants in the X and Y axes, and as a result, they are both bi-cones with different optical prescriptions. In some cases, the surface forms may have additional complexity as described by a polynomial function of several orders or by including the contribution of an aspherical shape.

[0048] In addition to the optical coating, the combiner 408 is generally arranged to redirect light through the use of one of the following optical elements applied across the area of the combiner, namely, a holographic optical element, a diffractive optical element, or an optical microstructure (none of which are shown). The use of these optical technologies can provide additional degrees of freedom to the system to redirect or orient the light beam of light in a manner that cannot be achieved through the use of a reflective coating alone. As an example, a holographic optical element or a diffractive optical element can redirect light at more extreme angles according to the laws of diffraction without the need to induce additional tilts to the combiner element as would be required if only reflective optical coatings whose design is limited by the laws of reflection were used.

[0049] In some cases, the combiner 408 is made of a plastic material and includes coatings with various functions as described above. The result is an efficient and highly transmissive component that is very suitable for use in extended reality optical designs. In most cases, the combiner has a transmittance suitable for viewing symbols and the extended reality view of the external world. When the optical device is used in a virtual environment, the transmittance of the combiner can be reduced close to zero.

[0050] The first mirror 406 is optically powered, and its front surface 420 can be eccentric and tilted. Different combinations of power, tilt, and eccentricity are used depending on the required layout and / or configuration of the device. The first mirror 406 is reflective on one side or the other. In the first case, the first mirror has a reflective first surface and light undergoes a first surface reflection from the reflective first surface. In a different case, the first mirror includes a transmissive first surface and a reflective second surface, and light passes through the mirror, undergoes a second surface reflection, and passes back through the first surface, in which case the element acts like a conventional lens with a reflective rear surface, adding additional degrees of freedom to the design.

[0051] The first mirror 406 is positioned near the intermediate image plane of the optical design, which means that its size and shape serve to define or limit the field of view of the image presented to the user. When light is not reflected by the mirror, it does not continue to travel towards the combiner and the user's eye; instead, it is absorbed by the surrounding chassis or support, thereby improving the control of stray light. The first mirror 406 serves to limit the visible field of view presented to the user by acting as an optical aperture. The first mirror 406 also enables the optical design to fold the optical path around the user's head and be tiltable or rotatable about two or more axes. Arranging the first mirror to be tilted can also serve to compensate for aberrations induced by the tilted combiner.

[0052] The second mirror 412 is tilted about at least a second axis relative to the axis of the first mirror and includes at least one partially reflective surface on either its inner or outer surface. The second mirror 412 is positioned at or near the aperture position of the system, between the relay lens and the first mirror, and is shaped to limit the light that travels towards the exit pupil presented to the user by also acting as an optical aperture.

[0053] The partially reflective surface of the second mirror is partially transparent to one or more wavelengths. As a result, the light passing through the optical device is filtered by reflecting only specific optical wavelengths in order to limit which wavelengths are directed towards the optical combiner, which can be beneficial since the optical coating applied to the combiner can be optimized to operate over a discrete set of wavelengths as opposed to the complete set of wavelengths emitted by the display or image source. This can help reduce the impact that the optical coating has on the real-world view seen by the user, for example, by maximizing transmission across the visible spectrum of wavelengths.

[0054] The second mirror can also be extended to enable additional features such as the ability to change the brightness of the virtual content. As an example, the mirror can have an electronically controllable reflectivity or transmittance, such that the user can control the brightness of the system by electronically controlling either the reflectivity or transmittance of the surface to allow more or less light to pass through the device. Alternatively, an electronically controllable filter, such as a liquid crystal device, can be placed on the mirror to provide variable absorption of the incident light, such that the user can control the brightness of the system by electronically controlling the absorption of either element to allow more or less light to pass through the device.

[0055] To optionally reduce stray light, an optical absorption region is placed behind the second mirror so that any transmitted light is properly absorbed and cannot return to the optical device.

[0056] As can be seen from FIG. 5, by substantially orthogonalizing the axes of each mirror, the optical path includes double reflections in at least two dimensions or axes. This means that the overall size of the optical device is reduced, further resulting in improvements in the number, weight, and efficiency of the components without sacrificing optical quality.

[0057] Although not shown in FIGS. 4 and 5, the optical device 402 is part of an optical system that includes additional features and functions. The optical system further includes an image source that generates light that is ultimately delivered to the user in the form of a virtual image. The image source comprises at least one self-emitting display (not shown), which can activate a plurality of emitting single pixel sources that emit visible light of one or more wavelengths to form a digital display. The light from the image source spreads over a given area and cone angle. This light is called a large cone emission and comes from a display called a large cone emission device or display. Typically, the angle of the cone of emission can be anywhere from about + / -90 degrees or much smaller cone angles, such as about + / -25 degrees, to fill the exit pupil of the designed system. This is why it is important to accurately control the unwanted cone angles, otherwise it can propagate the optical system to the eye.

[0058] The image source is a self-emitting display, a micro LED array, a plurality of display panels, or any other suitable source.

[0059] The image source is tilted with respect to the relay lens in at least one axis. In some cases, the image source is a micro LED display panel. The image generated through the optical system is combined with the real-world image from the combiner to provide an enlarged image. In other cases, multiple image sources may be used and combined using optical filters. For example, separate red, green, and blue display panels may be used instead of a single display panel that can emit red, green, and blue light and may be combined using a set of dichroic filters.

[0060] Alternatively, the optical device is, in some cases, wearable. In these cases, the optical device is housed in a housing attached to a helmet or other wearable frame, or forms an integral part of the helmet or frame. The optical device in these cases includes a head worn device (HWD), a head mounted device (HMD), or any other suitable device.

[0061] The content of the augmented image includes symbols related to the contact portion where the optical device or system is used. The symbols can include at least one or more of signs and symbols, data from sensors, processed data from sensors, combinations of sensor data, military symbols, vehicle-related symbols, scene-related symbols, position and positioning symbols, map symbols, speed and velocity symbols, etc. Additionally, a full-frame video can be displayed in addition to the symbols.

[0062] The optical device forms part of a system (not shown), and in some cases, this is used to control and / or navigate a vehicle within the environment. The system generates symbols and other information that needs to be displayed to the user. The system includes sensors for collecting data from the environment related to the vehicle, and a processor for receiving, transmitting, and processing the data to determine the data to be displayed to the user by the optical device according to the present invention. The user may be an aircraft pilot, and the system may be an aircraft system.

[0063] The optical device includes relay lenses 404, 600, which will be described in more detail below with reference to FIG. 6 showing several different arrangements of lenses 602, 604, and 606. These are three of many possible arrangements. The lenses are made of any suitable material. For weight reduction, the lenses are, at least in some cases, a plastic material or glass. The relay lens provides further improvement to the augmented reality optical design and is shown as part of this optical device, but can be used in many other situations where a high-quality and lightweight lens solution is required.

[0064] Relay lens 600 is designed to be as simple as possible while maintaining the required level of performance and minimizing cost and the number of components. The relay lens 600 for each arrangement 602, 604, and 606 comprises three lenses, namely two single lenses 608, 610 and one double lens 612. At least one or more of the lenses, in this case single lens 610, have a flat (planar) rear surface. It should be further noted that lenses 608 and 612 are arranged as a cemented optical doublet to provide a certain level of color correction.

[0065] Accordingly, in particular, a relay lens 600 is provided that comprises a series of coaxial lens elements.

[0066] In order of proximity to the image source, the first lens element within the series of coaxial lens elements is a plano-convex lens 610 arranged such that its flat rear surface faces the image source.

[0067] The second lens element within the series of coaxial lens elements is a bi-concave - bi-convex doublet 612, with the bi-concave portion facing the convex side of the first lens element.

[0068] The third lens element within the series of coaxial lens elements is a bi-convex lens 608.

[0069] Such a relay lens arrangement, together with the surrounding optical architecture described herein, can eliminate the need for additional lens elements elsewhere in the optical path.

[0070] As shown in arrangement 602, all lenses are positioned coaxially to simplify and facilitate assembly, but are positioned off the optical axis of the optical device. This arrangement is achieved by optimizing performance, and the lenses are decentered and tilted with respect to the axial ray path to correct for off-axis aberrations induced by the off-axis combiner. Additionally, the image plane is also tilted with respect to the lens assembly, particularly to achieve best focus. Arrangement 604 is the same as 602 and shows the central ray across the full field of view.

[0071] An extension of arrangements 602, 604 is that during design it is recognized that some of the lenses are not used, and as a result, the relay lens is cut away so that only a portion of the lenses that support the optical path are retained. During the design of multiple lenses, the trajectory of the light beam expected to pass through the lenses is identified. Material can be removed from each of the lenses of the multiple lenses that is not predicted to be traversed by the expected light beam. Changes to the lenses within the relay lens are used to update the augmented reality optical design.

[0072] Lens arrangement 606 is beneficial for mass / volume reduction, but functions the lens as additional individual apertures through which light that would normally pass through the upper part of the lens cannot pass. This avoids additional stray light in the optical device. A further means is, for example, to ensure that the relay lens element has a suitably absorptive edge by using black paint. Note that each optical prescription of the lenses in the arrangement can be configured as needed to conform to the required function.

[0073] The optical device can operate as a monocular device, but the most likely usage is as a binocular arrangement as shown in FIG. 7 having two optical devices 402. Each optical device includes an imaging optical system for either the user's right or left eye. As a result, all components can be designed off-the-shelf for simplicity, and the number of individual parts can be reduced. The optical paths for either eye do not cross, and the optical paths for either eye are completely separated. This improves configurability, maintenance options, and minimizes the risk of crosstalk or stray light between the two eyes. The displays are also completely independent, so if one optical channel fails or is damaged, the user still has the remaining display available in the other eye, and completely separate content can be provided to either eye, for example, stereoscopic content can be provided.

[0074] The binocular arrangement is supported by a frame, housing, or helmet designed to be worn by the user. As can be seen in FIG. 7, this figure is a top-down view showing only the axial light bundles for clarity. As shown, the mirrors are arranged to conveniently fold the optical system around the arc of the head (e.g., around the eyebrows), so that the mirrors are above and away from the user's line of sight, and the user's peripheral vision is not significantly affected.

[0075] This / each optical device is housed in a housing (not shown). The housing of the head-mounted device should be as lightweight as possible to avoid neck strain and other discomfort for the user. Not only should the housing be made small, but the housing must accommodate the optical device without any of the optical elements occupying any of the user's FOV. If the optical elements are "obtrusive", this can cause accidents and an unclear field of view for the user. The present invention provides a solution to these problems. As can be seen in FIG. 7, the optical elements 404, 406, 408, and 412 allow for a dual placement of the elements such that the lens assembly is positioned outside the field of view and around the head. Thus, the optical device is small, compact, and lightweight without sacrificing optical quality and performance.

[0076] FIGS. 8 and 9 show a simple mock-up of the final optical design. From these figures, it can be seen that light is emitted from an image source such as the radiation display described above and collected by a relay lens. The relay lens focuses the light towards a second mirror positioned near the optical aperture of the optical design. The mirror reflects the light towards a first mirror that also has optical power, and then the light is reflected towards a combiner element. The combiner is arranged to be partially see-through such that the display light is partially reflected towards the user while combining the view from the outside world.

[0077] Next, a method of operating the optical device will be described with reference to the flowchart of FIG. 10.

[0078] A method 1000 of operating an extended reality optical design is as follows.

[0079] In step 1002, light is emitted by an image source 424 over a given area and cone angle, and a portion is received by a relay lens assembly 404.

[0080] In step 1004, relay lens assembly 404 directs light towards an intermediate aperture within the system. Any light not transmitted by relay lens assembly 404 is mostly absorbed within the assembly, thus controlling stray light emitted by the image source.

[0081] In step 1006, second mirror 412 reflects a portion of the incident light received from relay lens assembly 404 towards first mirror 406. Any light outside the aperture of second mirror 412 is not reflected, thus helping to shape the exit pupil of optical device 402.

[0082] In step 1008, first mirror 406 receives the light and directs it towards combiner 408, and any light outside the aperture of first mirror 406 is not redirected, thus helping to shape the field of view of optical device 402.

[0083] In step 1010, combiner 408 receives the light from first mirror 406, partially redirects the light towards the user, and forms an exit pupil at the location of eye 400. As a result, the user can see a virtual display focused between approximately 30 cm and infinity, depending on the placement of relay lens assembly 404 and the positioning of the image source.

[0084] Directing light through the exit pupil of optical device 402, which is partially defined by the shape of relay lens assembly 404 and second mirror 212, to eye 400 minimizes the risk of the user seeing stray light or uncorrected portions of the image when the user moves eye 400 outside the defined / corrected exit pupil.

[0085] The exit pupil or eye box is the region within the space where the image appears sharp and in focus because it is optically well corrected. As the eye moves around this space, the sharpness of the virtual image can vary, and in particular, as the eye moves towards the edge of the defined exit pupil or outside the defined exit pupil, the sharpness of the virtual image can deteriorate. Typically, an optical display system is designed only to correct the image across the exit pupil as defined by optimization software. Instead, the present invention uses a number of apertures to ensure that the exit pupil cannot be made larger than designed due to additional light emission from the image source (i.e., at a larger angle in the emission cone).

[0086] There are many variations and ideas that can be included within the claims, and thus it will be understood that these alternatives are intended to be covered by the claims.

Claims

1. An optical device made according to an augmented reality optical design, the optical device comprising a plurality of optical elements for transmitting light from a light source for display to a user's eye, the optical device comprising a light source for generating the light, a lens assembly that is off-axis from the light source and configured to receive the light, a combiner that receives the light from the lens assembly via one or more additional optical elements of the plurality of optical elements and guides the light to form a virtual image at an exit pupil at the position of the eye and comprising, the combiner comprising a first inner optical surface form and a second outer optical surface form, the first inner optical surface form and the second outer optical surface form being different in order to minimize misalignment in an outer view from the combiner, an optical device.

2. The optical device according to claim 1, wherein the combiner is aspherical.

3. The optical device according to claim 1 or 2, wherein the combiner is tilted at least about a first axis.

4. The optical device according to any one of claims 1 to 3, wherein the combiner is off-axis with respect to a straight optical path.

5. The optical device according to any one of claims 1 to 4, wherein the combiner includes an optical coating over at least an optically active region of the combiner.

6. The optical device according to claim 5, wherein the combiner is made of a plastic material with a coating.

7. The optical device according to claim 5 or 6, wherein the coating is configured to provide different functionalities.

8. The optical device according to any one of claims 5 to 7, wherein the combiner includes one of a holographic optical element, a diffractive optical element, and an optical microstructure.

9. The optical device according to any one of claims 1 to 8, wherein the combiner has a variable thickness across the area of the combiner.

10. The optical device according to any one of claims 1 to 9, wherein the first inner optical surface form and the second outer optical surface form are bi-cones.

11. The optical device according to claim 10, wherein the first inner optical surface form and the second outer optical surface form are described by a multi-degree polynomial function.

12. The first inner optical surface form and the second outer optical surface form each have different radii of curvature along the X-axis and the Y-axis and are non-coaxial. The optical device according to any one of claims 1 to 11.

13. The first inner optical surface form and the second outer optical surface form each have different conic constants along the X-axis and the Y-axis. The optical device according to any one of claims 1 to 12.

14. Among the plurality of optical elements, the one or more further optical elements a first at least partially mirrored device, a second optical device disposed substantially orthogonally to the first at least partially mirrored device and positioned intermediate the lens assembly and the first at least partially mirrored device and the second optical device is configured to receive the light from the lens assembly and transmit the light to the first at least partially mirrored device. The optical device according to any one of claims 1 to 13.

15. The light source is a radiation source including a plurality of self-emitting pixels. The optical device according to any one of claims 1 to 14.

16. Each pixel is adapted for illumination and radiation over a wide cone angle. The optical device according to claim 15.

17. Each pixel has a cone angle greater than + / −25 degrees. The optical device according to claim 15 or 16.

18. The optical device is arranged to fold back the optical path about a first axis (XYZ) and a second axis (XYZ). The optical device according to any one of claims 1 to 17.

19. Forming part of a wearable device, at least a part of the optical device is folded back above or to the side of the user's eyebrows. The optical device according to any one of claims 1 to 18.

20. The lens assembly is a relay lens assembly. The optical device according to any one of claims 1 to 19.

21. A binocular optical device comprising two optical devices according to any one of claims 1 to 20.

22. A wearable device including one or two optical devices according to any one of claims 1 to 21.

23. A plurality of processors configured to transmit and receive data and process data, One or more sensors that collect at least a portion of the data from the environment and transmit the data to the processor One or more wearable devices according to claim 22 A system comprising the same

24. A method of guiding light through an optical device made according to an augmented reality optical design, the optical device comprising a plurality of optical elements for transmitting light from a light source for display to a user's eye, the method comprising Emitting light through a light source Guiding the light towards a combiner 408 via one or more additional optical devices Guiding the light through the combiner to form a virtual image at the exit pupil of the optical device Comprising The combiner comprises a first inner optical surface form and a second outer optical surface form, the first inner optical surface form and the second outer optical surface form being different in order to minimize the deviation in the outer view from the combiner, a method

25. The combiner being aspherical The combiner being tiltable at least about a first axis The combiner being off-axis with respect to the straight optical path The combiner comprising an optical coating over at least the optically active region of the combiner The combiner being made of a plastic material The combiner comprising one of a holographic optical element, a diffractive optical element, and an optical microstructure The method according to claim 24, further comprising the combiner having at least one of the above

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