SYSTEM AND METHOD FOR BINOCULOUS DISTORTION COMPENSATION OF A DISPLAY - Patent application

Abstract

To provide systems and methods for suitable display binocular deformation compensation.SOLUTION: A display subsystem for a virtual image generation system used by an end user, comprises first and second waveguide apparatuses, first and second projection sub-assemblies configured for introducing first and second light beams respectively into the first and second waveguide apparatuses, such that at least a first light ray and at least a second light ray respectively exit the first and second waveguide apparatuses to display first and second monocular images as a binocular image to the end user, and a light sensing assembly configured for detecting at least one parameter indicative of a mismatch between the displayed first and second monocular images as the binocular image.SELECTED DRAWING: Figure 20

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This disclosure claims priority to U.S. Provisional Application No. 62 / 698,015, filed July 13, 2018, and entitled “SYSTEMS AND METHODS FOR DISPLAY BINOCULAR DEFORMATION COMPENSATION.”This application incorporates, as if fully set forth, the following patent applications and publications: U.S. Patent Application No. 14 / 555,585, filed November 27, 2014, published on July 23, 2015 as U.S. Patent Publication No. 2015 / 0205126; U.S. Patent Application No. 15 / 274,823, filed September 23, 2016, published on March 30, 2017 as U.S. Patent Publication No. 2017 / 0091996; U.S. Patent Application No. 15 / 274,823, filed November 2, 2016, published on May 4, 2017 as U.S. Patent Publication No. 2017 / 0124 No. 15 / 341,822, filed November 2, 2016, published as U.S. Patent Publication No. 2017 / 0122725 on May 4, 2017; U.S. Patent Application No. 15 / 341,760, filed January 12, 2017, published as U.S. Patent Publication No. 2017 / 0199384 on July 13, 2017; U.S. Patent Application No. 15 / 405,146, filed December 21, 2017; U.S. Provisional Patent Application No. 62 / 609,242, filed December 21, 2018; No. 16 / 230,169, filed on January 17, 2019, U.S. Provisional Patent Application No. 16 / 250,931, filed on January 17, 2019, U.S. Provisional Patent Application No. 16 / 251,017, filed on July 13, 2018, U.S. Provisional Patent Application No. 62 / 698,015, filed on December 19, 2018, and published on June 20, 2019 as U.S. Patent Publication No. 2019 / 0187490; Each of U.S. Patent Application No. 16 / 225,961, filed July 9, 2018, published as U.S. Patent Publication No. 2018 / 0341112 on November 29, 2018, U.S. Patent Application No. 16 / 030,713, filed June 11, 2019, and U.S. Patent Application No. 16 / 437,229, filed November 27, 2014, published as U.S. Patent Publication No. 2015 / 0205126 on July 23, 2015, is incorporated by reference in its entirety.

[0002] The present invention relates generally to systems and methods configured to facilitate interactive virtual or augmented reality environments for one or more users. [Background technology]

[0003] Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images or portions thereof are presented to a user in a manner that appears or may be perceived as real. Virtual reality (VR) scenarios typically involve the presentation of digital or virtual image information without transparency to other actual real-world visual inputs, while augmented reality (AR) scenarios typically involve the presentation of digital or virtual image information as an extension to the visualization of the real world around the end user.

[0004] For example, referring to Figure 1, an augmented reality scene 4 is depicted in which a user of the AR technology sees a real-world park-like setting 6 featuring people, trees, buildings in the background, and a concrete platform 8. In addition to these items, the end user of the AR technology also perceives as "seeing" a robotic figure 10 standing on the real-world platform 8, and a flying cartoon-like avatar character 12 that appears to be an anthropomorphic bumblebee, although these elements 10, 12 do not exist in the real world. The human visual perception system is highly complex, making it difficult to create VR or AR technology that facilitates a comfortable, natural-feeling, and rich presentation of virtual image elements among other virtual or real-world image elements.

[0005] VR and AR systems typically employ head-mounted displays (or helmet-mounted displays or smart glasses) that are at least loosely coupled to the end user's head and therefore move as the user's head moves. When movement of the end user's head is detected by the display subsystem, the data being displayed can be updated to account for changes in head pose (i.e., the orientation and / or location of the user's head).

[0006] As an example, when a user wearing a head mounted display views a virtual representation of a three-dimensional (3D) object on the display and walks around the area in which the 3D object appears, the 3D object can be re-rendered for each viewpoint, giving the end user the perception of walking around an object that occupies real space. When a head mounted display is used to present multiple objects in a virtual space (e.g., a rich virtual world), head pose measurements can be used to re-render the scene to match the end user's dynamically changing head location and orientation to provide an increased sense of immersion in the virtual space.

[0007] Head-mounted displays that enable AR (i.e., simultaneous viewing of real and virtual elements) can have several different types of configurations. In one such configuration, often referred to as a "video see-through" display, a camera captures elements of a real scene, a computing system superimposes virtual elements onto the captured real scene, and a non-transparent display presents the composite image to the eye. Another configuration, often referred to as an "optical see-through" display, allows the end user to look through a transparent (or semi-transparent) element in the display subsystem to directly view light from real objects in the environment. The transparent element, often referred to as a "combiner," superimposes the light from the display over the end user's viewpoint in the real world.

[0008] VR and AR systems typically employ a display subsystem having a projection subsystem and a display surface positioned in front of the end user's field of view onto which the projection subsystem projects image frames in succession. In a true three-dimensional system, the depth of the display surface can be controlled at frame rates or sub-frame rates. The projection subsystem may include one or more optical fibers into which light from one or more light sources emits different colored light in a defined pattern, and a scanning device that scans the optical fibers in a predetermined pattern to create image frames that are displayed in succession to the end user.

[0009] In one embodiment, the display subsystem includes one or more planar optical waveguides, approximately parallel to the user's field of view, into which light from an optical fiber is launched. One or more linear diffraction gratings are embedded within the waveguide to change the angle of incident light propagating along the waveguide. By changing the angle of the light beyond the total internal reflection (TIR) ​​threshold, the light escapes from one or more side faces of the waveguide. Linear diffraction gratings have low diffraction efficiency, and therefore, each time the light encounters a linear diffraction grating, only a portion of the light energy is directed out of the waveguide. By out-coupling the light at multiple locations along the grating, the exit pupil of the display subsystem is effectively increased. The display subsystem may further include one or more collimation elements that collimate the light emerging from the optical fiber, and an optical input device that optically couples the collimated light to or from an edge of the waveguide. Summary of the Invention [Means for solving the problem]

[0010] This disclosure describes techniques for compensating for binocular deformations that occur in display devices, such as devices that are components of AR or VR systems.

[0011] At least some embodiments are directed to a display subsystem for a virtual image generating system for use by an end user. The subsystem may include first and second waveguide devices, first and second projection subassemblies configured to introduce first and second light beams into the first and second waveguide devices, respectively, such that at least a first light beam and at least a second light beam exit the first and second waveguide devices, respectively, and display the first and second monocular images as binocular images to the end user, and a light sensing assembly configured to detect at least one parameter indicative of a misalignment between the first and second monocular images displayed as binocular images. Embodiments may optionally include one or more of the following aspects.

[0012] In some embodiments, the first and second projection subassemblies each include one or more light sources configured to generate light and an optical coupling assembly configured to collimate the light into separate light beams and couple the separate light beams into separate waveguide devices.

[0013] In some embodiments, each optical coupling assembly comprises a collimation element configured to collimate the individual light beams into individual collimated light beams, and an internal coupling element (ICE) configured to optically couple the individual collimated light beams into individual waveguide devices.

[0014] In some embodiments, the first and second waveguide devices each comprise a planar optical waveguide in which respective ICEs are configured to optically combine respective collimated light beams as internally combined light beams, an orthogonal pupil expansion (OPE) element associated with the planar optical waveguide for splitting the respective internally combined light beams into multiple orthogonal light beams, and an exit pupil expansion (EPE) element associated with the planar optical waveguide for splitting the multiple orthogonal light beams into light rays exiting the respective planar optical waveguides.

[0015] In some embodiments, the individual planar optical waveguides comprise a single substrate formed from a single plate of optically transparent material, and the first and second waveguide devices each have a partially transparent display surface configured to be positioned within the field of view between an end user's eye and the surrounding environment.

[0016] In some embodiments, the display subsystem further comprises a frame structure configured to be worn by an end user, and the first and second waveguide devices are left and right eyepieces carried by the frame structure.

[0017] In some embodiments, the frame structure comprises a frame that carries the left and right eyepieces and a bridge onto which the light-sensing assembly is affixed.

[0018] In some embodiments, the frame structure comprises left and right cantilevered arms extending from a bridge, with the left eyepiece being affixed to the first cantilevered arm and the second eyepiece being affixed to the second cantilevered arm.

[0019] In some embodiments, the optical sensing assembly is optically coupled to the first and second waveguide devices, but rigidly decoupled from the first and second waveguide devices.

[0020] In some embodiments, the first and second waveguide devices each comprise an outcoupling element configured to optically couple light from the respective first and second waveguide devices to a light-sensing assembly, and at least one detected parameter is derived from the light outcoupled from the first and second waveguide devices.

[0021] In some embodiments, the light-sensing assembly comprises two independent sensing arrays configured to separately detect light outcoupled from the first and second waveguide devices.

[0022] In some embodiments, the light-sensing assembly comprises a single sensor configured to detect light outcoupled from the first and second waveguide devices.

[0023] In some embodiments, the light-sensing assembly comprises an optical waveguide device configured to propagate light outcoupled from the first and second waveguide devices to a single sensor.

[0024] In some embodiments, the light sensing assembly comprises at least one non-imaging sensor, and the at least one detected parameter is indicative of an angle at which at least a first light beam exits the first waveguide device and an angle at which at least a second light beam exits the second waveguide device.

[0025] In some embodiments, the at least one detected parameter includes intensities of two light rays, each representative of at least a first light ray and at least a second light ray, the two representative light rays exiting the first and second waveguide devices, respectively, outside the field of view of the end user.

[0026] In some embodiments, the optical sensing assembly includes at least one imaging sensor, and the at least one detected parameter includes first and second representative virtual monocular images generated by the first and second waveguide devices, respectively.

[0027] In some embodiments, the first and second representative virtual monocular images are identical copies of the first and second virtual monocular images displayed to the end user.

[0028] In some embodiments, the first and second representative virtual monocular images are test virtual monocular images that are separate from the first and second virtual monocular images displayed to the end user.

[0029] In some embodiments, the test virtual monocular image is displayed by separate first and second waveguide devices outside the field of view of the end user.

[0030] At least some embodiments are directed to a virtual image generation system including a display subsystem, which may optionally include one or more of these aspects, and a control subsystem configured to correct a misalignment between the first and second monocular images based on at least one parameter detected by the light-sensing assembly.

[0031] In some embodiments, the virtual image generation system further comprises a memory configured to store calibration profiles for the first and second waveguide devices, and the control subsystem is configured to correct misalignment between the first and second monocular images by modifying the stored calibration profiles.

[0032] In some embodiments, the virtual image generation system further comprises a memory configured to store the three-dimensional scene, the control subsystem configured to render a plurality of composite image frames of the three-dimensional scene, and the display subsystem configured to sequentially display the plurality of image frames to an end user.

[0033] At least some embodiments are directed to a virtual image generation system for use by an end user, the system comprising: a left and right projection subassembly configured to project light into the left and right eyepieces such that the left and right monocular images are displayed to the end user as binocular images; a light sensing assembly configured to detect at least one parameter indicative of a misalignment between the left and right monocular images displayed as binocular images; a frame structure configured to be worn by an end user, the frame structure configured to position the left and right eyepieces in front of the end user's eyes, respectively; and a control subsystem configured to correct the misalignment between the left and right monocular images based on the at least one detected parameter detected by the light sensing assembly. Embodiments can optionally include one or more of the following aspects.

[0034] In some embodiments, the left and right projection subassemblies each include one or more light sources configured to generate light and an optical coupling assembly configured to collimate the light into separate light beams and couple the separate light beams into separate eyepieces.

[0035] In some embodiments, each optical coupling assembly comprises a collimation element configured to collimate the individual light beams into individual collimated light beams, and an internal coupling element (ICE) configured to optically couple the individual collimated light beams into individual eyepieces.

[0036] In some embodiments, the left and right eyepieces each comprise a planar optical waveguide in which respective ICEs are configured to optically combine the respective collimated light beams as internally combined light beams, an orthogonal pupil expansion (OPE) element associated with the planar optical waveguide for splitting the respective internally combined light beams into multiple orthogonal light beams, and an exit pupil expansion (EPE) element associated with the planar optical waveguide for splitting the multiple orthogonal light beams into light rays exiting the respective planar optical waveguides.

[0037] In some embodiments, the individual planar optical waveguides comprise a single substrate formed from a single plate of optically transparent material.

[0038] In some embodiments, the left and right projection subassemblies are carried by the frame structure and the light-sensing assembly is carried by the frame structure.

[0039] In some embodiments, the frame structure comprises a frame that carries the left and right eyepieces and a bridge onto which the light-sensing assembly is affixed.

[0040] In some embodiments, the frame structure comprises left and right cantilevered arms extending from a bridge, with the left eyepiece affixed to the left cantilevered arm and the right eyepiece affixed to the right cantilevered arm.

[0041] In some embodiments, the light-sensing assembly is optically coupled to the left and right eyepieces, but rigidly decoupled from the left and right eyepieces.

[0042] In some embodiments, the left and right eyepieces each comprise an out-coupling element configured to optically couple light from the respective left and right eyepieces to the light-sensing assembly, and at least one detected parameter is derived from the light out-coupled from the left and right eyepieces.

[0043] In some embodiments, the light-sensing assembly comprises two independent sensing arrays configured to separately detect light outcoupled from the left and right eyepieces.

[0044] In some embodiments, the light-sensing assembly comprises a single sensor configured to detect light outcoupled from the left and right eyepieces.

[0045] In some embodiments, the light-sensing assembly comprises an optical waveguide device configured to propagate light outcoupled from the left and right eyepieces to a single sensor.

[0046] In some embodiments, the light sensing assembly includes at least one non-imaging sensor, and the at least one detected parameter is indicative of an angle at which a light beam exits the left eyepiece and an angle at which a second light beam exits the right eyepiece.

[0047] In some embodiments, the at least one detected parameter includes the intensities of two light beams representing the first light beam and the second light beam, respectively.

[0048] In some embodiments, the representative light rays exit the left and right eyepieces, respectively, outside the field of view of the end user.

[0049] In some embodiments, the light sensing assembly includes at least one imaging sensor, and the at least one detected parameter includes left and right representative virtual monocular images generated by the left and right eyepieces, respectively.

[0050] In some embodiments, the left and right representative virtual monocular images are identical copies of the left and right virtual monocular images displayed to the end user.

[0051] In some embodiments, the left and right representative virtual monocular images are test virtual monocular images that are separate from the left and right virtual monocular images displayed to the end user.

[0052] In some embodiments, the test virtual monocular image is displayed by separate left and right eyepieces outside the end user's field of view.

[0053] In some embodiments, the virtual image generation system further comprises a memory configured to store calibration profiles for the left and right eyepieces, and the control subsystem is configured to correct misalignment between the left and right monocular images by modifying the stored calibration profiles.

[0054] In some embodiments, the virtual image generation system further comprises a memory configured to store the three-dimensional scene, the control subsystem configured to render a plurality of composite image frames of the three-dimensional scene, and the display subsystem configured to sequentially display the plurality of image frames to an end user.

[0055] At least some embodiments are directed to a display system comprising: a pair of projection assemblies configured to emit light, the pair of projection assemblies comprising a first projection assembly and a second projection assembly; a pair of eyepieces comprising a first eyepiece optically coupled to the first projection assembly and a second eyepiece optically coupled to the second projection assembly; a sensing assembly comprising a pair of imaging sensors configured to capture an image, the pair of imaging sensors comprising a first imaging sensor optically coupled to the first projection assembly via the first eyepiece and a second imaging sensor optically coupled to the second projection assembly via the second eyepiece; and one or more processors in communication with the pair of projection assemblies and the pair of imaging sensors, the one or more processors configured to receive data representing an image captured by the second imaging sensor and to control operation of the first projection assembly based at least in part on the data received from the second imaging sensor. Embodiments can optionally include one or more of the following aspects.

[0056] 48. The display system of claim 47, wherein in some embodiments the one or more processors are further configured to receive data representing an image captured by the first imaging sensor and to control operation of the second projection assembly based, at least in part, on the data received from the first imaging sensor.

[0057] In some embodiments, to control operation of the first projection assembly based at least in part on data received from the second imaging sensor, the one or more processors are configured to control operation of the first projection assembly based at least in part on data received from the first and second imaging sensors.

[0058] In some embodiments, to control operation of the second projection assembly based at least in part on data received from the first imaging sensor, the one or more processors are configured to control operation of the second projection assembly based at least in part on data received from the first and second imaging sensors.

[0059] In some embodiments, the sensing assembly further comprises an elongated body physically coupled to the pair of imaging sensors.

[0060] In some embodiments, the first imaging sensor is physically coupled to a first distal portion of the elongated body and the second imaging sensor is physically coupled to a second distal portion of the elongated body.

[0061] In some embodiments, the first imaging sensor is physically coupled to the elongated body in laterally aligned with the second imaging sensor.

[0062] In some embodiments, the display system further comprises a housing structure, the sensing assembly being mounted to an inner surface of the housing structure.

[0063] In some embodiments, the one or more processors are further configured to generate an image of the virtual scene from a perspective of a first rendering camera and cause the first projection assembly to emit light representing the image of the virtual scene as generated from the perspective of the first rendering camera, and to generate an image of the virtual scene from a perspective of a second rendering camera and cause the second projection assembly to emit light representing the image of the virtual scene as generated from the perspective of the second rendering camera.

[0064] In some embodiments, to control operation of the first projection assembly based, at least in part, on data received from the second imaging sensor, the one or more processors are configured to control one or more auxiliary parameters of the first rendering camera based, at least in part, on data received from the second imaging sensor.

[0065] In some embodiments, the one or more processors are further configured to receive data representing the image captured by the first imaging sensor and to control operation of the second projection assembly based at least in part on the data received from the first imaging sensor, and to control operation of the second projection assembly based at least in part on the data received from the first imaging sensor, the one or more processors are configured to control one or more associated parameters of the second rendering camera based at least in part on the data received from the first imaging sensor.

[0066] At least some embodiments are directed to a head mounted display system comprising a housing structure, a pair of projection assemblies configured to emit light, a light-sensing assembly mounted to an inner surface of the housing structure, a pair of eyepieces configured to optically couple the pair of projection assemblies to the sensing assembly, and one or more processors in communication with the pair of projection assemblies and the light-sensing assemblies, the one or more processors configured to control operation of the pair of projection assemblies based at least in part on data received from the light-sensing assemblies. Embodiments can optionally include one or more of the following aspects.

[0067] In some embodiments, each eyepiece in the pair of eyepieces comprises a respective waveguide device and a respective internal coupling element configured to internally couple light emitted by a respective one of the pair of projection assemblies into the respective waveguide device, and a respective external coupling element configured to couple light from the respective one of the pair of projection assemblies that is guided within the respective waveguide device out of the respective waveguide device.

[0068] In some embodiments, a first portion of the individual external coupling element is configured to couple light from a respective one of the pair of projection assemblies guided within the respective waveguide devices out of the respective waveguide devices towards a respective eye of a user, and a second portion of the individual external coupling element is configured to couple light from a respective one of the pair of projection assemblies guided within the respective waveguide devices out of the respective waveguide devices towards a light-sensing assembly.

[0069] In some embodiments, each eyepiece in the pair of eyepieces includes an individual exit pupil expansion (EPE) element configured to split light from a respective one of the pair of projection assemblies, which is guided within a respective waveguide device, into multiple light beams that exit the respective waveguide device and are directed to a respective eye of a user.

[0070] In some embodiments, the light-sensing assembly is rigidly decoupled from the pair of eyepieces.

[0071] 2, the display subsystem 20 can include one or more light sources 22 that generate light, an optical fiber 24 that emits light, and a collimation element 26 that collimates the light exiting a distal end of the optical fiber 24 into a light beam 36. The display subsystem 20 further includes a piezoelectric element 28 against or within which the optical fiber 24 is mounted as a fixed-free flexible cantilever, and drive electronics 30 electrically coupled to the piezoelectric element 22 to activate and electrically stimulate the piezoelectric element 28 to oscillate the distal end of the optical fiber 24 about a fulcrum 34 in a predetermined scan pattern creating a deflection 32, thereby scanning the collimated light beam 36 according to the scan pattern.

[0072] The display subsystem 20 comprises a waveguide device 38 including a planar optical waveguide 40, generally parallel to the field of view of an end user, a diffractive optical element (DOE) 42 associated with the planar optical waveguide 40, and an internal coupling element (ICE) 42 (in the form of a DOE) integrated into the end of the planar optical waveguide 40. The ICE 42 internally couples and redirects the collimated light 36 from the collimation element 26 into the planar optical waveguide 40. The collimated light beam 36 from the collimation element 26 propagates along the planar optical waveguide 40 and intersects with the DOE 42, causing a portion of the light to exit the face of the waveguide device 38 towards the end user's eye as a focused light ray 46 at a viewing distance according to the lensing coefficient of the planar optical waveguide 40. Thus, the light source 22 in conjunction with the driving electronics 30 generates spatially and / or temporally varying image data encoded in the form of light.

[0073] The location of each pixel visualized by an end user is highly dependent on the angle of the light ray 48 exiting the planar optical waveguide 40. Thus, light rays 48 exiting the waveguide 40 at different angles will create pixels at different locations within the end user's field of view. For example, if it is desired to locate the pixel at the top right of the end user's field of view, the collimated light beam 36 may be input into the waveguide device 38 at one angle, and if it is desired to locate the pixel at the center of the end user's field of view, the collimated light beam 36 may be input into the waveguide device 38 at a second, different angle. Thus, as the optical fiber 24 is scanned according to a scan pattern, the light beam 36 emanating from the optical fiber 24 will be input into the waveguide device 38 at different angles, thereby creating pixels at different locations within the end user's field of view. Thus, the location of each pixel within the end user's field of view is highly dependent on the angle of the light rays 48 exiting the planar optical waveguide 40, and thus the locations of these pixels are encoded within the image data generated by the display subsystem 20.

[0074] Although the angle of the light beam 36 entering the waveguide device 38, and therefore the angle of the light beam 36 entering the planar optical waveguide 40, will be different from the angle of the light rays 48 exiting the planar optical waveguide 40, the relationship between the angle of the light beam 36 entering the waveguide device 38 and the angle of the light rays 48 exiting the planar optical waveguide 40 is well known and predictable, and therefore the angle of the light rays 48 exiting the planar optical waveguide 40 can be readily predicted from the angle of the collimated light beam 36 entering the waveguide device 38.

[0075] From the foregoing, it can be seen that the actual angle of the light beam 36 entering the waveguide device 38 from the optical fiber 24, and therefore the actual angle of the light ray 48 exiting the waveguide 40 towards the end user, will be the same or nearly the same or a one-to-one relationship to the designed angle of the exiting light ray 48, such that the location of the pixel viewed by the end user is properly encoded within the image data generated by the display subsystem 20. However, due to manufacturing tolerances between different scanners as well as changing environmental conditions, such as temperature fluctuations, which can change the consistency of the bonding materials used to integrate the display subsystem 20 together, the actual angle of the exiting light ray 48 will, without compensation, vary from the designed angle of the exiting light ray 48, thereby creating pixels that are in the wrong place within the end user's field of view, resulting in image distortion.

[0076] In some embodiments, the two waveguide devices 38 of the display subsystem 20 may take the form of a left eyepiece 70L and a right eyepiece 70R, respectively, as illustrated in FIG. 3. Such eyepieces 70L, 70R may be incorporated into a pair of binocular matching eyepieces. Although each eyepiece 70L, 70R may be internally rigid, in such embodiments, the two eyepieces 70L, 70R may be flexible / deformable relative to one another due to the form factor of the frame structure (not shown). This deformation issue becomes significant, especially as the form factor of the frame structure becomes lighter, thinner, and flexible to facilitate transportation, comfort, and a more aesthetically appealing appearance. In some circumstances, the relative movement of the two eyepieces 70L, 70R may introduce distortion and other errors into the virtual binocular image to be projected onto the user's retina.

[0077] For example, as illustrated in Figures 4A-4D, an exemplary representation of virtual content may be presented through a pair of eyepieces 70L, 70R as part of a virtual image generation system and perceived by the left and right eyes, respectively. As shown in Figure 4A, the two eyepieces 70L, 70R are aligned with each other in an ideal manner. In other words, the alignment of the two eyepieces 70L, 70R has not changed since the time of manufacture of the virtual image generation system. Thus, the virtual image generation system may generate left and right monocular virtual content 72L, 72R and present it to the user's eyes through the two eyepieces 70L, 70R as binocularly aligned virtual content 74.

[0078] However, if the alignment of the two eyepieces 70L, 70R were to hypothetically change at some point after the time of manufacture of the virtual image generation system, the alignment of the pair of eyepieces 70L, 70R in each of Figures 4B, 4C, and 4D may differ from that of Figure 4A. As illustrated in Figures 4B, 4C, and 4D, post-factory changes in the alignment of the pair of eyepieces 70L, 70R about the pitch, roll, and yaw axes may result in the left and right virtual content 72L, 72R being presented and perceived through the pair of eyepieces 70L, 70R as binocularly misaligned virtual content 74, as shown in Figures 4B, 4C, and 4D, respectively. Such misalignment between the left and right eyepieces 70L, 70R may result in a perceived translational and / or rotational misalignment between the left and right virtual content 72L, 72R. Furthermore, studies have shown that binocular misalignment can cause physiological fatigue on the human visual system, and humans are sensitive to binocular rotational misalignment of virtual images about the pitch, roll, and yaw axes of up to 4, 6, and 10 arc minutes, respectively. As described in further detail below, compensation for binocular eyepiece misalignment can be achieved using systems and techniques to directly derive light intended for the left and right eyes and comparatively sense and correct the relative misalignment in the virtual image.

[0079] According to a first aspect of the present invention, a display subsystem for a virtual image generation system for use by an end user is provided. The display subsystem comprises a first and a second waveguide device. In one embodiment, the first and the second waveguide device are each configured to be positioned in front of an eye of an end user. In another embodiment, the first and the second waveguide device each have a partially transparent display surface configured to be positioned within a field of view between the eye of the end user and the surrounding environment. In yet another embodiment, the display subsystem further comprises a frame structure configured to be worn by the end user, where the first and the second waveguide device are left and right eyepieces carried by the frame structure.

[0080] The display subsystem further includes first and second projection subassemblies configured to introduce the first and second light beams into the first and second waveguide devices, respectively, such that at least a first light beam and at least a second light beam exit the first and second waveguide devices, respectively, and display the first and second monocular images as binocular images to an end user.

[0081] In one embodiment, the first and second projection subassemblies each include one or more light sources configured to generate light and an optical coupling assembly configured to collimate the light into individual light beams and couple the individual light beams into individual waveguide devices. The optical coupling assembly may include a collimation element configured to collimate the individual light into individual collimated light beams and an internal coupling element (ICE) configured to optically couple the individual collimated light beams into the individual waveguide devices. In this case, the first and second waveguide devices may each include a planar optical waveguide (e.g., a single substrate formed from a single plate surface of an optically transparent material) in which the individual ICEs are configured to optically combine the individual collimated light beams as internally combined light beams, an orthogonal pupil expansion (OPE) element associated with the planar optical waveguide for splitting the individual internally combined light beams into multiple orthogonal light beams, and an exit pupil expansion (EPE) element associated with the planar optical waveguide for splitting the multiple orthogonal light beams into light rays that exit the individual planar optical waveguides.

[0082] In this embodiment, each of the first and second projection subassemblies may further comprise a scanning device configured to scan the light generated by the respective one or more light sources in a predetermined scan pattern in response to a control signal. Each scanning device may comprise an optical fiber configured to emit the light generated by the respective one or more light sources and a mechanical drive assembly configured to displace the respective optical fiber according to the predetermined scan pattern. Each mechanical drive assembly may comprise a piezoelectric element to which the optical fiber is mounted and drive electronics configured to transmit an electrical signal to the piezoelectric element, thereby vibrating the optical fiber according to the predetermined scan pattern.

[0083] The display subsystem further includes a light sensing assembly configured to detect at least one parameter indicative of a misalignment between the first and second monocular images displayed as a binocular image.

[0084] In an embodiment, the display subsystem further comprises a frame structure having a frame carrying the first and second waveguide devices as left and right eyepieces and a bridge onto which the light-sensing assembly is affixed. The frame structure may further have left and right cantilevered arms extending from the bridge, where the left eyepiece is affixed to the left cantilevered arm and the right eyepiece is affixed to the right cantilevered arm. In another embodiment, the light-sensing assembly is optically coupled to but rigidly decoupled from the first and second waveguide devices.

[0085] In yet another embodiment, the first and second waveguide devices each include an out-coupling element configured to optically couple light from the respective first and second waveguide devices to the optical sensing assembly, where the detected parameter is derived from the out-coupled light from the first and second waveguide devices. The optical sensing assembly may include two independent sensing arrays configured to separately detect the out-coupled light from the first and second waveguide devices. Or the optical sensing assembly may include a single sensor configured to detect the out-coupled light from the first and second waveguide devices. In this case, the optical sensing assembly may include an optical waveguide device configured to propagate the out-coupled light from the first and second waveguide devices to the single sensor.

[0086] In yet another embodiment, the light sensing assembly comprises at least one non-imaging sensor, in which case the detected parameters may be indicative of an angle at which the first light beam exits the first waveguide device and an angle at which the second light beam exits the second waveguide device. The detected parameters may include intensities of two light beams, representing the first light beam and the second light beam, respectively. The two representative light beams may exit the first and second waveguide devices, respectively, outside the field of view of the end user.

[0087] In yet another embodiment, the light sensing assembly includes at least one imaging sensor, where the detected parameters may include first and second representative virtual monocular images generated by the first and second waveguide devices, respectively. The first and second representative virtual monocular images may be identical copies of the first and second virtual monocular images displayed to the end user. Or the first and second representative virtual monocular images may be test virtual monocular images separate from the first and second virtual monocular images displayed to the end user. The test virtual monocular images may be displayed by separate first and second waveguide devices outside the field of view of the end user.

[0088] According to a second aspect of the present invention, a virtual image generation system comprises a display subsystem as described above and a control subsystem configured to correct a misalignment between the first and second monocular images based on parameters detected by the light-sensing assembly. In one embodiment, the virtual image generation system further comprises a memory configured to store a calibration profile for the first and second waveguide devices, where the control subsystem may be configured to correct a misalignment between the first and second monocular images by modifying the stored calibration profile. In another embodiment, the virtual image generation system further comprises a memory configured to store a three-dimensional scene, where the control subsystem may be configured to render a plurality of composite image frames of the three-dimensional scene, where the display subsystem may be configured to sequentially display the plurality of image frames to an end user.

[0089] According to a third aspect of the present invention, there is provided a virtual image generation system for use by an end user, the virtual image generation system comprising left and right eyepieces, each of which may have a partially transparent display surface configured to be positioned within a field of view between an eye of the end user and a surrounding environment.

[0090] The virtual image generation system further comprises left and right projection subassemblies configured to project light into the left and right eyepieces such that left and right monocular images are displayed to an end user as binocular images.

[0091] In one embodiment, the left and right projection subassemblies each include one or more light sources configured to generate light, and an optical coupling assembly configured to collimate the light into individual light beams and couple the individual light beams into individual eyepieces. Each optical coupling assembly may include a collimation element configured to collimate the individual light into individual collimated light beams, and an internal coupling element (ICE) configured to optically couple the individual collimated light beams into the individual eyepieces. The left and right eyepieces may each include a planar optical waveguide (e.g., a single substrate formed from a single plate surface of an optically transparent material) in which the individual ICEs are configured to optically couple the individual collimated light beams as internally coupled light beams, an orthogonal pupil expansion (OPE) element associated with the planar optical waveguide to split the individual internally coupled light beams into multiple orthogonal light beams, and an exit pupil expansion (EPE) element associated with the planar optical waveguide to split the multiple orthogonal light beams into light rays exiting the individual planar optical waveguides.

[0092] In another embodiment, the left and right projection subassemblies each include a scanning device configured to scan the light generated by the respective light source in a predetermined scan pattern in response to a control signal. Each scanning device may include an optical fiber configured to emit the light generated by the respective light source and a mechanical drive assembly configured to displace the respective optical fiber according to the predetermined scan pattern. Each mechanical drive assembly may include a piezoelectric element to which the optical fiber is mounted and drive electronics configured to communicate an electrical signal to the piezoelectric element, thereby vibrating the optical fiber according to the predetermined scan pattern.

[0093] The virtual image generation system further comprises a light-sensing assembly configured to detect at least one parameter indicative of a misalignment between the left and right monocular images displayed as a binocular image. The virtual image generation system further comprises a frame structure configured to be worn by an end user. The frame structure is configured to position the left and right eyepieces, respectively, in front of the eyes of the end user. In one embodiment, the left and right projection subassemblies are carried by the frame structure and the light-sensing assembly is carried by the frame structure. In another embodiment, the frame structure comprises a frame carrying the left and right eyepieces and a bridge onto which the light-sensing assembly is affixed. The frame structure may comprise left and right cantilevered arms extending from the bridge, the left eyepiece may be affixed to the left cantilevered arm and the right eyepiece may be affixed to the right cantilevered arm. In another embodiment, the light-sensing assembly is optically coupled to the left and right eyepieces but rigidly decoupled from the left and right eyepieces.

[0094] In yet another embodiment, the left and right eyepieces each comprise an out-coupling element configured to optically couple light from the respective left and right eyepieces to the light-sensing assembly, in which case the detected parameter can be derived from the out-coupled light from the left and right eyepieces. The light-sensing assembly may comprise two independent sensing arrays configured to separately detect the out-coupled light from the left and right eyepieces. Or the sensing assembly may comprise a single sensor configured to detect the out-coupled light from the left and right eyepieces. In this case, the light-sensing assembly may comprise an optical waveguide device configured to propagate the out-coupled light from the left and right eyepieces to the single sensor.

[0095] In yet another embodiment, the light-sensing assembly comprises at least one non-imaging sensor, and the detected parameters are indicative of an angle at which the light beam exits the left eyepiece and an angle at which the second light beam exits the right eyepiece. The detected parameters may include intensities of two light beams, representing the first light beam and the second light beam, respectively. The two representative light beams may exit the first and second waveguide devices, respectively, outside the field of view of the end user.

[0096] In yet another embodiment, the light sensing assembly includes at least one imaging sensor, in which case the detected parameters may include left and right representative virtual monocular images generated by the left and right eyepieces, respectively. The left and right representative virtual monocular images may be identical copies of the left and right virtual monocular images displayed to the end user. Or the left and right representative virtual monocular images may be test virtual monocular images separate from the left and right virtual monocular images displayed to the end user. The test virtual monocular images may be displayed by separate left and right eyepieces outside the field of view of the end user.

[0097] The virtual image generation system further comprises a control subsystem configured to correct the misalignment between the left and right monocular images based on the parameters detected by the light-sensing assembly. In one embodiment, the virtual image generation system further comprises a memory configured to store a calibration profile for the left and right eyepieces, where the control subsystem may be configured to correct the misalignment between the left and right monocular images by modifying the stored calibration profile. In another embodiment, the virtual image generation system further comprises a memory configured to store a three-dimensional scene, where the control subsystem may be configured to render a plurality of composite image frames of the three-dimensional scene, where the display subsystem may be configured to sequentially display the plurality of image frames to an end user. The present specification also provides, for example, the following items: (Item 1) 1. A display subsystem for a virtual image generation system for use by an end user, comprising: a first waveguide device and a second waveguide device; a first projection subassembly and a second projection subassembly configured to introduce a first light beam and a second light beam into the first waveguide device and the second waveguide device, respectively, such that at least a first light beam and at least a second light beam exit the first waveguide device and the second waveguide device, respectively, to display a first monocular image and a second monocular image to the end user as a binocular image; a light-sensing assembly configured to detect at least one parameter indicative of a misalignment between a first monocular image and a second monocular image displayed as the binocular image; A display subsystem comprising: (Item 2) 2. The display subsystem of claim 1, wherein the first projection subassembly and the second projection subassembly each comprise one or more light sources configured to generate light and an optical coupling assembly configured to collimate the light into individual light beams and couple the individual light beams into individual waveguide devices. (Item 3) 3. The display subsystem of item 2, wherein each optical coupling assembly comprises a collimation element configured to collimate individual light into an individual collimated light beam, and an internal coupling element (ICE) configured to optically couple the individual collimated light beam into the individual waveguide device. (Item 4) 4. The display subsystem of claim 3, wherein the first waveguide device and the second waveguide device each include a planar optical waveguide in which an individual ICE is configured to optically combine the individual collimated light beams as an internally combined light beam, an orthogonal pupil expansion (OPE) element associated with the planar optical waveguide for splitting the individual internally combined light beams into multiple orthogonal light beams, and an exit pupil expansion (EPE) element associated with the planar optical waveguide for splitting the multiple orthogonal light beams into light rays exiting the individual planar optical waveguides. (Item 5) 5. The display subsystem of claim 4, wherein the individual planar optical waveguides comprise a single substrate formed from a single plate of optically transparent material. (Item 6) 2. The display subsystem of item 1, wherein the first waveguide device and the second waveguide device each have a partially transparent display surface configured to be positioned within a field of view between the end user's eye and the surrounding environment. (Item 7) 2. The display subsystem of item 1, further comprising a frame structure configured to be mounted by the end user, the first waveguide device and the second waveguide device being a left eyepiece lens and a right eyepiece lens carried by the frame structure. (Item 8) 8. The display subsystem of item 7, wherein the frame structure comprises a frame supporting the left and right eyepieces and a bridge onto which the light-sensing assembly is affixed. (Item 9) 9. The display subsystem of item 8, wherein the frame structure comprises a left cantilevered arm and a right cantilevered arm extending from the bridge, the left eyepiece being affixed to a first cantilevered arm and the second eyepiece being affixed to the second cantilevered arm. (Item 10) 8. The display subsystem of claim 7, wherein the light-sensing assembly is optically coupled to the first waveguide device and the second waveguide device but rigidly decoupled from the first waveguide device and the second waveguide device. (Item 11) 2. The display subsystem of claim 1, wherein the first and second waveguide devices each include an external coupling element configured to optically couple light from the respective first and second waveguide devices to a light-sensing assembly, and the at least one detected parameter is derived from light externally coupled from the first and second waveguide devices. (Item 12) Item 12. The display subsystem of item 11, wherein the light sensing assembly comprises two independent sensing arrays configured to separately detect light outcoupled from the first and second waveguide devices. (Item 13) Item 12. The display subsystem of item 11, wherein the light-sensing assembly comprises a single sensor configured to detect light outcoupled from the first waveguide device and the second waveguide device. (Item 14) Item 14. The display subsystem of item 13, wherein the light-sensing assembly comprises an optical waveguide device configured to propagate light outcoupled from the first waveguide device and the second waveguide device to the single sensor. (Item 15) 2. The display subsystem of claim 1, wherein the light sensing assembly comprises at least one non-imaging sensor, and the at least one detected parameter indicates an angle at which the at least a first light beam exits the first waveguide device and an angle at which the at least a second light beam exits the second waveguide device. (Item 16) Item 16. The display subsystem of item 15, wherein the at least one detected parameter includes intensities of two light beams representing the at least first light beam and the at least second light beam, respectively. (Item 17) Item 17. The display subsystem of item 16, wherein two representative light rays exit the first waveguide device and the second waveguide device, respectively, outside the field of view of the end user. (Item 18) 2. The display subsystem of item 1, wherein the light sensing assembly comprises at least one imaging sensor, and the at least one detected parameter includes a first representative virtual monocular image and a second representative virtual monocular image generated by the first waveguide device and the second waveguide device, respectively. (Item 19) 20. The display subsystem of item 18, wherein the first representative virtual monocular image and the second representative virtual monocular image are identical copies of the first virtual monocular image and the second virtual monocular image displayed to the end user. (Item 20) 20. The display subsystem of item 18, wherein the first representative virtual monocular image and the second representative virtual monocular image are test virtual monocular images separate from the first virtual monocular image and the second virtual monocular image displayed to the end user. (Item 21) 21. The display subsystem of item 20, wherein the test virtual monocular image is displayed by separate first and second waveguide devices outside the field of view of the end user. (Item 22) 1. A virtual image generation system, comprising: A display subsystem as recited in item 1; a control subsystem configured to correct a misalignment between the first monocular image and the second monocular image based on at least one parameter detected by the light-sensing assembly; and A virtual image generation system comprising: (Item 23) 23. The virtual image generation system of item 22, further comprising a memory configured to store calibration profiles for the first waveguide device and the second waveguide device, and the control subsystem configured to correct misalignment between the first monocular image and the second monocular image by modifying the stored calibration profiles. (Item 24) 23. The virtual image generation system of item 22, further comprising a memory configured to store a three-dimensional scene, the control subsystem configured to render a plurality of composite image frames of the three-dimensional scene, and the display subsystem configured to sequentially display the plurality of image frames to the end user. (Item 25) 1. A virtual image generation system for use by an end user, comprising: A left eyepiece and a right eyepiece; a left projection subassembly and a right projection subassembly configured to project light into the left and right eyepieces such that left and right monocular images are displayed to the end user as binocular images; a light-sensing assembly configured to detect at least one parameter indicative of a misalignment between a left monocular image and a right monocular image displayed as the binocular image; a frame structure configured to be worn by the end user, the frame structure configured to position the left and right eyepieces, respectively, in front of the end user's eyes; and a control subsystem configured to correct a misalignment between the left and right monocular images based on at least one detected parameter detected by the light-sensing assembly; and A virtual image generation system comprising: (Item 26) 26. The virtual image generating system of item 25, wherein the left projection subassembly and the right projection subassembly each comprise one or more light sources configured to generate light and an optical coupling assembly configured to collimate the light into separate light beams and couple the separate light beams into separate eyepieces. (Item 27) 27. The virtual image generating system of item 26, wherein each optical coupling assembly comprises a collimation element configured to collimate individual lights into individual collimated light beams, and an internal coupling element (ICE) configured to optically couple the individual collimated light beams into the individual eyepieces. (Item 28) 28. The virtual image generation system of item 27, wherein the left eyepiece and the right eyepiece each include a planar optical waveguide in which an individual ICE is configured to optically combine the individual collimated light beams as an internally combined light beam, an orthogonal pupil expansion (OPE) element associated with the planar optical waveguide for splitting the individual internally combined light beams into multiple orthogonal light beams, and an exit pupil expansion (EPE) element associated with the planar optical waveguide for splitting the multiple orthogonal light beams into light rays exiting the individual planar optical waveguides. (Item 29) 30. The virtual image generating system of claim 28, wherein the individual planar optical waveguides comprise a single substrate formed from a single plate of optically transparent material. (Item 30) 26. The virtual image generation system of claim 25, wherein the left projection subassembly and the right projection subassembly are carried by the frame structure, and the light-sensing assembly is carried by the frame structure. (Item 31) 26. The virtual image generation system of item 25, wherein the frame structure comprises a frame carrying the left and right eyepieces and a bridge onto which the light-sensing assembly is affixed. (Item 32) 32. The virtual image generation system of claim 31, wherein the frame structure comprises a left cantilevered arm and a right cantilevered arm extending from the bridge, the left eyepiece being affixed to the left cantilevered arm and the right eyepiece being affixed to the right cantilevered arm. (Item 33) 26. The virtual image generation system of claim 25, wherein the light-sensing assembly is optically coupled to the left and right eyepieces but rigidly decoupled from the left and right eyepieces. (Item 34) Item 35. The virtual image generation system of item 25, wherein the left and right eyepieces each comprise an out-coupling element configured to optically couple light from the respective left and right eyepieces to the light-sensing assembly, and the at least one detected parameter is derived from light out-coupled from the left and right eyepieces. Item 35. The virtual image generation system of item 34, wherein the light sensing assembly comprises two independent sensing arrays configured to separately detect light coupled out from the left and right eyepieces. (Item 36) Item 35. The virtual image generation system of item 34, wherein the light sensing assembly comprises a single sensor configured to detect light outcoupled from the left and right eyepieces. (Item 37) Item 37. The virtual image generation system of item 36, wherein the light sensing assembly comprises an optical waveguide device configured to propagate light outcoupled from the left and right eyepieces to the single sensor. (Item 38) 26. The virtual image generation system of item 25, wherein the light sensing assembly comprises at least one non-imaging sensor, and the at least one detected parameter indicates an angle at which a light beam exits the left eyepiece and an angle at which a second light beam exits the right eyepiece. (Item 39) 39. The virtual image generation system of item 38, wherein the at least one detected parameter includes intensities of two light rays representing the first light ray and the second light ray, respectively. (Item 40) 40. The virtual image generation system of item 39, wherein representative light rays exit the left and right eyepieces, respectively, outside the field of view of the end user. (Item 41) 26. The virtual image generation system of item 25, wherein the light sensing assembly includes at least one imaging sensor, and the at least one detected parameter includes a left representative virtual monocular image and a right representative virtual monocular image generated by the left eyepiece and right eyepiece, respectively. (Item 42) 42. The virtual image generation system of claim 41, wherein the left representative virtual monocular image and the right representative virtual monocular image are identical copies of the left virtual monocular image and the right virtual monocular image displayed to the end user. (Item 43) 42. The virtual image generation system of claim 41, wherein the left representative virtual monocular image and the right representative virtual monocular image are test virtual monocular images separate from the left virtual monocular image and the right virtual monocular image displayed to the end user. (Item 44) Item 44. The virtual image generation system of item 43, wherein the test virtual monocular image is displayed outside the field of view of the end user through separate left and right eyepieces. (Item 45) 26. The virtual image generation system of item 25, further comprising a memory configured to store calibration profiles for the left and right eyepieces, and the control subsystem configured to correct misalignment between the left and right monocular images by modifying the stored calibration profiles. (Item 46) 26. The virtual image generation system of item 25, further comprising a memory configured to store a three-dimensional scene, the control subsystem configured to render a plurality of composite image frames of the three-dimensional scene, and the display subsystem configured to sequentially display the plurality of image frames to the end user. (Item 47) 1. A display system comprising: a pair of projection assemblies configured to emit light, the pair of projection assemblies comprising a first projection assembly and a second projection assembly; A pair of eyepieces, a first eyepiece optically coupled to the first projection assembly; a second eyepiece optically coupled to the second projection assembly; and A pair of eyepieces comprising: 1. A sensing assembly comprising a pair of imaging sensors configured to capture an image, the pair of imaging sensors comprising: a first imaging sensor optically coupled to the first projection assembly through the first eyepiece; a second imaging sensor optically coupled to the second projection assembly through the second eyepiece; and a sensing assembly comprising: one or more processors in communication with the pair of projection assemblies and the pair of imaging sensors, the one or more processors comprising: receiving data representative of an image captured by the second imaging sensor; controlling operation of the first projection assembly based at least in part on data received from the second imaging sensor; one or more processors configured to A display system comprising: (Item 48) The one or more processors further include: receiving data representative of an image captured by the first imaging sensor; controlling operation of the second projection assembly based at least in part on data received from the first imaging sensor; Item 48. The display system of item 47, configured to perform the following: (Item 49) to control operation of the first projection assembly based at least in part on data received from the second imaging sensor, the one or more processors: Controlling operation of the first projection assembly based at least in part on data received from the first imaging sensor and the second imaging sensor. Item 49. The display system of item 48, configured as follows: (Item 50) to control operation of the second projection assembly based at least in part on data received from the first imaging sensor, the one or more processors: Controlling operation of the second projection assembly based at least in part on data received from the first imaging sensor and the second imaging sensor. Item 49. The display system of item 48, configured as follows: (Item 51) The sensing assembly further comprises: Item 48. The display system of item 47, comprising an elongated body physically coupled to the pair of imaging sensors. (Item 52) Item 52. The display system of item 51, wherein the first imaging sensor is physically coupled to a first distal portion of the elongated body and the second imaging sensor is physically coupled to a second distal portion of the elongated body. (Item 53) Item 52. The display system of item 51, wherein the first imaging sensor is physically coupled to the elongated body in laterally aligned with the second imaging sensor. (Item 54) Item 48. The display system of item 47, further comprising a housing structure, the sensing assembly being mounted to an inner surface of the housing structure. (Item 55) The one or more processors further include: generating an image of the virtual scene from a perspective of a first rendering camera; causing the first projection assembly to emit light representing an image of a virtual scene as generated from a perspective of the first rendering camera; generating an image of the virtual scene from a viewpoint of a second rendering camera; causing the second projection assembly to emit light representative of an image of the virtual scene as generated from a perspective of the second rendering camera; Item 48. The display system of item 47, configured to perform the following: (Item 56) to control operation of the first projection assembly based at least in part on data received from the second imaging sensor, the one or more processors: Controlling one or more extrinsic parameters of the first rendering camera based, at least in part, on data received from the second imaging sensor. Item 56. A display system as described in item 55, configured as follows. (Item 57) The one or more processors further include: receiving data representative of an image captured by the first imaging sensor; controlling operation of the second projection assembly based at least in part on data received from the first imaging sensor; configured to: to control operation of the second projection assembly based at least in part on data received from the first imaging sensor, the one or more processors: Controlling one or more extrinsic parameters of the second rendering camera based, at least in part, on data received from the first imaging sensor. Item 56. A display system as described in item 55, configured as follows. (Item 58) 1. A head mounted display system, comprising: The housing structure, a pair of projection assemblies configured to emit light; a light-sensing assembly mounted to an interior surface of the housing structure; a pair of eyepieces configured to optically couple the pair of projection assemblies to the sensing assembly; one or more processors in communication with the pair of projection assemblies and the light-sensing assembly, the one or more processors configured to control operation of the pair of projection assemblies based, at least in part, on data received from the light-sensing assemblies; A display system comprising: (Item 59) Each eyepiece in the pair of eyepieces is A separate waveguide device; a respective incoupling element configured to incoupling light emitted by a respective one of the pair of projection assemblies into the respective waveguide device; a respective out-coupling element configured to couple light from a respective one of the pair of projection assemblies that is guided within the respective waveguide device out of the respective waveguide device; Item 59. The display system of item 58, comprising: (Item 60) a first portion of the respective external coupling element configured to couple light from a respective one of the pair of projection assemblies that is guided within the respective waveguide device out of the respective waveguide device towards a respective eye of a user; a second portion of the respective external coupling element configured to couple light from a respective one of the pair of projection assemblies that is guided within the respective waveguide device out of the respective waveguide device towards the light-sensing assembly. Item 60. The display system of item 59. (Item 61) Each eyepiece in the pair of eyepieces is an individual exit pupil extension (EPE) element configured to split light from a respective one of the pair of projection assemblies that is guided within the respective waveguide device into a plurality of light beams that exit the respective waveguide device and are directed to respective eyes of a user; 60. The display system of item 59, comprising: (Item 62) Item 60. The display system of item 59, wherein the light-sensing assembly is rigidly decoupled from the pair of eyepiece lenses.

[0098] Additional and other objects, features, and advantages of the present invention are set forth in the detailed description, drawings, and claims. [Brief description of the drawings]

[0099] This patent or patent application contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0100] The drawings described below are for illustration purposes only and are not intended to limit the scope of the present disclosure.

[0101] The drawings described below are for illustration purposes only. The drawings are not intended to limit the scope of the disclosure. This patent or application contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the U.S. Patent Office upon request and payment of the necessary fee.

[0102] The drawings illustrate the design and utility of preferred embodiments of the present invention, where like elements are referred to by common reference numerals. In order to better understand how the foregoing and other advantages and objects of the present invention are obtained, a more particular description of the invention, briefly described above, will be given by reference to specific embodiments thereof which are illustrated in the accompanying drawings. With the understanding that these drawings depict only typical embodiments of the invention and therefore should not be considered as limiting its scope, the present invention will be explained and described with additional specificity and detail through the use of the accompanying drawings.

[0103] [Figure 1] FIG. 1 is a photograph of a three-dimensional augmented reality scene that may be displayed to an end user by a prior art augmented reality generating device.

[0104] [Diagram 2] FIG. 2 is a plan view of a prior art display subsystem that may be used in an augmented reality generation device.

[0105] [Diagram 3] FIG. 3 is a plan view of left and right eyepieces that may be used in the prior art display subsystem of FIG.

[0106] [Figure 4A] FIG. 4A is a plan view of the left and right eyepieces of FIG. 3, where the left and right eyepieces are aligned.

[0107] [Figure 4B] FIG. 4B is a plan view of the left and right eyepieces of FIG. 3, where the left and right eyepieces are rotationally misaligned about the pitch axis.

[0108] [Figure 4C] FIG. 4C is a plan view of the left and right eyepieces of FIG. 3, where the left and right eyepieces are rotationally misaligned about the roll axis.

[0109] [Figure 4D] FIG. 4D is a plan view of the left and right eyepieces of FIG. 3, where the left and right eyepieces are rotationally misaligned about the yaw axis.

[0110] [Diagram 5] FIG. 5 is a block diagram of a virtual image generation system constructed in accordance with one embodiment of the present invention.

[0111] [Figure 6A] FIG. 6A is a plan view of one technique that may be used to mount the virtual image generation system of FIG.

[0112] [Figure 6B] FIG. 6B is a plan view of another technique that can be used to mount the virtual image generation system of FIG.

[0113] [Figure 6C] FIG. 6C is a plan view of yet another technique that can be used to mount the virtual image generation system of FIG.

[0114] [Figure 6D] FIG. 6D is a plan view of yet another technique that can be used to mount the virtual image generation system of FIG.

[0115] [Figure 7] FIG. 7 is a plan view of one embodiment of a display subsystem for use in the virtual image generation system of FIG.

[0116] [Figure 8] FIG. 8 is one embodiment of a planar optical waveguide for use in the display subsystem of FIG.

[0117] [Figure 9] FIG. 9 is a plan view of an exemplary frame generated by the virtual image generation system of FIG.

[0118] [Figure 10] FIG. 10 is a plan view of one scanning pattern that may be used to generate the example frame of FIG.

[0119] [Figure 11] FIG. 11 is a plan view of another scanning pattern that can be used to generate another example frame.

[0120] [Figure 12] FIG. 12 is a plan view of yet another scanning pattern that can be used to generate yet another example frame.

[0121] [Figure 13] FIG. 13 is a plan view of yet another scanning pattern that can be used to generate yet another example frame.

[0122] [Figure 14A] 14A is a plan view of one embodiment of a left eyepiece for use in the display subsystem of FIG.

[0123] [Figure 14B] 14B is a plan view of another embodiment of a left eyepiece for use in the display subsystem of FIG.

[0124] [Figure 14C] 14C is a plan view of yet another embodiment of a left eyepiece for use in the display subsystem of FIG.

[0125] [Figure 14D] 14D is a plan view of yet another embodiment of a left eyepiece for use in the display subsystem of FIG.

[0126] [Figure 14E]14E is a plan view of yet another embodiment of a left eyepiece for use in the display subsystem of FIG.

[0127] [Figure 15] FIG. 15 is a cross-sectional view of the left eyepiece of FIG. 14A taken along line 15-15.

[0128] [Figure 16] FIG. 16 is a cross-sectional view of the left eyepiece of FIG. 14A taken along line 16-16.

[0129] [Figure 17A] FIG. 17A is a perspective view of the waveguide device of FIG. 14A, specifically showing the output beam being focused to infinite viewing distance.

[0130] [Figure 17B] FIG. 17B is a perspective view of the waveguide device of FIG. 14A, particularly showing the output light beam being focused to a first non-infinite viewing distance.

[0131] [Figure 17C] FIG. 17C is a perspective view of the waveguide device of FIG. 14A, particularly showing the output light beam being focused to a second, non-infinite viewing distance.

[0132] [Figure 18] FIG. 18 is a cross-sectional view of the left eyepiece of FIG. 14B taken along line 18-18.

[0133] [Figure 19] FIG. 19 is a cross-sectional view of the left eyepiece of FIG. 14B taken along line 19-19.

[0134] [Figure 20] 20 is a top view of a frame structure associated with a display subsystem and a photosensor assembly for use in the virtual image generation system of FIG. 5. FIG.

[0135] [Figure 21] FIG. 21 is a front view of the frame structure of FIG.

[0136] [Figure 22A] FIG. 22A is a top view of the frame structure of FIG. 20 with the left and right eyepieces relatively aligned.

[0137] [Figure 22B] FIG. 22B is a top view of the frame structure of FIG. 20 with the left and right eyepieces relatively misaligned.

[0138] [Figure 23A] FIG. 23A is a perspective view of a display screen showing the correspondence between one beam angle of a collimated light beam and pixels in an end user's field of view (FOV).

[0139] [Figure 23B] FIG. 23B is a perspective view of a display screen illustrating the correspondence between different beam angles of a collimated light beam and pixels within an end user's field of view (FOV).

[0140] [Figure 24] FIG. 24 is a perspective view of the projection of the angles of light rays emanating from the display screen of FIG. 23A projected onto the xz and yz planes.

[0141] [Diagram 25] FIG. 25 is a plan view of a photosensor assembly for use in the frame structure of FIG. 14A.

[0142] [Figure 26A] 26A is a plan view of one embodiment of an orthogonal sensor of the sensing assembly of FIG. 25. FIG.

[0143] [Figure 26B] 26B is a plan view of another embodiment of an orthogonal sensor of the sensing assembly of FIG. 25. FIG.

[0144] [Figure 26C] 26C is a plan view of yet another embodiment of an orthogonal sensor of the sensing assembly of FIG. 25. FIG.

[0145] [Figure 27A] FIG. 27A is a schematic diagram of an exemplary dielectric layer transmission-angle relationship.

[0146] [Figure 27B] FIG. 27B is a schematic diagram of the photodetector intensity-voltage relationship.

[0147] [Figure 28A] FIG. 28A is a schematic perspective view illustrating light rays exiting the left eyepiece relative to the xy plane.

[0148] [Figure 28B] FIG. 28B is a schematic plan view illustrating the light rays of FIG. 23a projected onto the xy plane.

[0149] [Figure 29A] 29A is a top view of one embodiment of a four quadrant sensor of the sensing assembly of FIG. 25. FIG.

[0150] [Figure 29B] 29B is a top view of one embodiment of a position sensitive detector (PSD) of the sensing assembly of FIG. 25.

[0151] [Diagram 30] 30 is a top view of a frame structure associated with a display subsystem and another photosensor assembly for use in the virtual image generation system of FIG. 5. FIG.

[0152] [Figure 31A] 31A is a front view of yet another optical sensor assembly for use in the virtual image generation system of FIG. 5. FIG.

[0153] [Figure 31B] FIG. 31B is a perspective view of the optical sensor assembly of FIG. 31A.

[0154] [Figure 32A] 32A is a perspective view of a front housing structure associated with a display subsystem for use in the image generation system of FIG. 5. FIG.

[0155] [Figure 32B] FIG. 32B is another perspective view of the front housing structure of FIG. 32A with a corresponding rear housing structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0156] The following description relates to display subsystems and methods to be used in virtual reality and / or augmented reality systems, however, it should be understood that while the present invention is useful for application in virtual or augmented reality systems, the invention in its broadest aspects may not be so limited.

[0157] With reference to FIG. 5, one embodiment of a virtual image generation system 100 constructed in accordance with the present invention will now be described. The virtual image generation system 100 may be operated as an augmented reality subsystem to provide images of virtual objects mixed with physical objects in the field of view of the end user 50. There are two basic approaches in operating the virtual image generation system 100. The first approach employs one or more imagers (e.g., cameras) to capture images of the surrounding environment. The virtual image generation system 100 blends virtual images into data representing the images of the surrounding environment. The second approach employs one or more at least partially transparent surfaces through which the surrounding environment is viewed and on which the virtual image generation system 100 generates images of virtual objects.

[0158] The virtual image generation system 100 and the various techniques taught herein may also be employed in applications other than augmented reality and virtual reality subsystems. For example, the various techniques may be applied to any projection or display subsystem, or to a pico-projector where movement may be performed by the end user's hands rather than the head. Thus, while often described herein in terms of an augmented reality or virtual reality subsystem, the present teachings should not be limited to such subsystems for such use.

[0159] For at least augmented reality applications, it may be desirable to spatially position various virtual objects relative to individual physical objects within the field of view of the end user 50. Virtual objects, also referred to herein as virtual tags or tags or callouts, may take a wide variety of forms, essentially any of a variety of data, information, concepts, or logical structures capable of being represented as an image. Non-limiting examples of virtual objects may include virtual text objects, virtual numeric objects, virtual alphanumeric objects, virtual tag objects, virtual field objects, virtual chart objects, virtual map objects, virtual instrumentation objects, or virtual visual representations of physical objects.

[0160] The virtual image generation system 100 comprises a frame structure 102 worn by an end user 50, a display subsystem 104 carried by the frame structure 102 such that the display subsystem 104 is positioned in front of the eye 52 of the end user 50, and a speaker 106 carried by the frame structure 102 such that the speaker 106 is positioned adjacent to the ear canal of the end user 50 (optionally, another speaker (not shown) is positioned adjacent the other ear canal of the end user 50 to provide stereo / shapeable sound control). The display subsystem 104 is designed to present a light-based radiation pattern to the eye 52 of the end user 50 that may be comfortably perceived as an augmentation to physical reality with a high level of image quality and three-dimensional perception, and may be capable of presenting two-dimensional content. The display subsystem 104 presents a sequence of frames at high frequencies, providing the perception of a single coherent scene.

[0161] In the illustrated embodiment, the display subsystem 104 employs an "optical see-through" display through which a user can view light directly from real objects through a transparent (or semi-transparent) element. The transparent element, often referred to as a "combiner," superimposes the light from the display over the user's field of view in the real world. The display subsystem 104 comprises left and right projection subsystems 108L, 108R and left and right partially transparent display screens (or eyepieces) 110L, 110R onto which the projection subsystems 108L, 108R project left and right monocular images. As will be explained in further detail below, the frame structure 102 is designed to carry two transparent eyepieces 110 so as to position the eyepieces 110 in front of the eyes 52 of the end user 50 for presentation of a monocular image to the end user 50 as a binocular image, and to position the eyepieces 110 within the field of view of the end user 50 between the eyes 52 of the end user 50 and the surrounding environment so that direct light from the surrounding environment is transmitted through the eyepieces 110 to the eyes 52 of the end user 50, respectively.

[0162] In the illustrated embodiment, each of the projection assemblies 108L, 108R provides scanning light to a partially transparent eyepiece 110L, 110R, respectively. For example, each of the projection subsystems 108L, 108R may take the form of a fiber optic scanning-based projection device into which the scanning light from each of the projection subsystems 108L, 108R is injected to produce, for example, an image at a single optical viewing distance closer to infinity (e.g., arm's length), images at multiple discrete optical viewing distances or focal planes, and / or image layers stacked at multiple viewing distances or focal planes to represent a stereoscopic 3D object. In some embodiments, each of the projection subsystems 108L, 108R may comprise a spatial light modulator ("SLM"), such as a liquid crystal on silicon ("LCoS") component. In some embodiments, each of the projection subsystems 108L, 108R may comprise another type of scanning device, such as a microelectromechanical ("MEMs") scanning mirror. Examples of other projection subsystem configurations that may be employed in one or more embodiments are provided in U.S. Patent Application No. 14 / 555,585, filed November 27, 2014, and published on July 23, 2015 as U.S. Patent Publication No. 2015 / 0205126, the entirety of which is incorporated herein by reference.

[0163] These layers in the light field may be stacked closely enough together to appear continuous together to the human visual subsystem (e.g., one layer is within the perturbation cone of an adjacent layer). Additionally or alternatively, a photographic element may be blended across two or more layers to increase the perceived continuity of the transition between layers in the light field even when the layers are more sparsely stacked (e.g., one layer is outside the perturbation cone of an adjacent layer).

[0164] The virtual image generation system 100 further comprises one or more sensors 103 (shown in FIGS. 20 and 21 ) mounted to the frame structure 102 for detecting the position and movement of the head 54 of the end user 50 and / or the position and interocular distance of the eyes of the end user 50. Such sensors may include image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, wireless devices, and / or gyroscopes).

[0165] The virtual image generation system 100 further comprises a user orientation detection module 112 that detects the instantaneous position of the end user's 50 head 54 and may predict the position of the end user's 50 head 54 based on the position data received from the sensor. The detection of the instantaneous position of the end user's 50 head 54 facilitates the determination of the specific real object the end user 50 is looking at, thereby providing an indication of the specific text message to be generated for that real object, and further provides an indication of the text region to which the text message should be streamed. The user orientation module 112 also tracks the eyes 52 of the end user 50 based on the tracking data received from the sensor.

[0166] The virtual image generation system 100 further comprises a control subsystem, which may take any of a wide variety of forms. The control subsystem includes a number of controllers, such as one or more microcontrollers, microprocessors or central processing units (CPUs), digital signal processors, graphic processing units (GPUs), other integrated circuit controllers, such as application specific integrated circuits (ASICs), programmable gate arrays (PGAs), such as field programmable gate arrays (FPGAs), and / or programmable logic controllers (PLUs). In some embodiments, the control subsystem includes and / or communicates with one or more processors that perform the operations described herein, for example, through the execution of executable instructions.

[0167] In the illustrated embodiment, the control subsystem of virtual image generation system 100 includes a central processing unit (CPU) 114, a graphics processing unit (GPU) 116, one or more frame buffers 118, and a 3D database 120 for storing three-dimensional data. CPU 114 controls the overall operation, while GPU 116 renders frames (e.g., converts a three-dimensional scene into a two-dimensional image) from the three-dimensional data stored in 3D database 120 and stores these frames in frame buffer 116. Although not shown, one or more additional integrated circuits may control the reading of frames into and / or from frame buffer 116 and the operation of projection assembly 108 of display subsystem 104.

[0168] The virtual image generation system 100 further comprises a light-sensing assembly 122 configured to sense at least one parameter indicative of a misalignment between the left and right monocular images displayed as a binocular image. In the illustrated embodiment, the light-sensing assembly 122 accomplishes this by sensing light rays exiting both eyepieces 110L, 110R. The detected parameters may be used to calibrate or recalibrate the binocular alignment of the monocular images displayed on the eyepieces 110, as will be described in more detail below.

[0169] Various processing components of the virtual image generation system 100 may be physically contained within a distributed subsystem. For example, as illustrated in Figures 6a-6d, the virtual image generation system 100 includes a local processing and data module 130 that is operatively coupled to the display subsystem 104 and the sensors, such as by wired leads or wireless connectivity 136. The local processing and data module 130 may be mounted in a variety of configurations, such as fixedly attached to the frame structure 102 (Figure 6a), fixedly attached to a helmet or hat 56 (Figure 6b), embedded within headphones, removably attached to a torso 58 of the end user 50 (Figure 6c), or removably attached to the waist 60 of the end user 50 in a belt-type configuration (Figure 6d). The virtual image generation system 100 further includes a remote processing module 132 and a remote data repository 134 operably coupled to the local processing and data module 130 by wired or wireless connectivity 138, 140, etc., and these remote modules 132, 134 are operably coupled to each other and available as resources to the local processing and data module 130.

[0170] The local processing and data module 130 may comprise a power efficient processor or controller and digital memory such as flash memory, both of which may be utilized to aid in the processing, caching, and storage of data captured from the sensors and / or acquired and / or processed using the remote processing module 132 and / or the remote data repository 134, possibly for passage to the display subsystem 104 after such processing or readout. The remote processing module 132 may comprise one or more relatively powerful processors or controllers configured to analyze and process the data and / or image information. The remote data repository 134 may comprise a relatively large digital data storage facility that may be available through the Internet or other networking configurations in a "cloud" resource configuration. In one embodiment, all data is stored and all calculations are performed in the local processing and data module 130, allowing for fully autonomous use from any remote module.

[0171] The couplings 136, 138, 140 between the various components mentioned above may include one or more wired interfaces or ports to provide wired or optical communication, or one or more wireless interfaces or ports via RF, microwave, IR, and the like to provide wireless communication. In some embodiments, all communication may be wired, while in other embodiments, all communication may be wireless. In still further embodiments, the wired and wireless communication options may differ from those illustrated in FIGS. 6a-6d. Thus, the particular options of wired or wireless communication should not be considered limiting.

[0172] In the illustrated embodiment, the user orientation module 112 is contained within a local processing and data module 130 while the CPU 114 and GPU 116 are contained within a remote processing module 132, although in alternative embodiments the CPU 114, GPU 124, or portions thereof, may be contained within the local processing and data module 130. The 3D database 120 can be associated with a remote data repository 134.

[0173] 7, each projection assembly 108 includes one or more light sources 150 (only one is shown in FIG. 7) that generate light (e.g., emit different colored light in a defined pattern). The light sources 150 may take any of a wide variety of forms, for example, a set of RGB lasers (e.g., laser diodes capable of outputting red, green, and blue light) operable to generate coherent collimated light in red, green, and blue colors, respectively, according to a defined pixel pattern defined within an individual frame of pixel information or data. Laser light provides high color saturation and is very energy efficient.

[0174] Each projection assembly 108 further comprises a scanning device 152 (only one is shown in FIG. 7 ) that scans light in a predetermined scan pattern in response to a control signal. The scanning device 152 comprises one or more optical fibers 154 (e.g., single mode optical fibers), each having a proximal end 154a into which light is received from the light source 150 and a distal end 154b from which light is provided to the eyepiece 110. The scanning device 152 further comprises a mechanical drive assembly 156 to which the optical fibers 154 are mounted. The drive assembly 156 is configured to displace the distal end 154b of each optical fiber 154 about a fulcrum 158 in accordance with the scan pattern.

[0175] To this end, the drive assembly 156 comprises a piezoelectric element 160 on which the optical fiber 154 is mounted, and drive electronics 162 are configured to transmit electrical signals to the piezoelectric element 160, thereby vibrating the distal end 154b of the optical fiber 154 according to a scanning pattern. The operation of the light source 150 and the drive electronics 162 are thus coordinated in a manner to generate image data encoded in the form of spatially and / or temporally varying light. A description of optical fiber scanning techniques is provided in US 2015 / 0309264, expressly incorporated herein by reference.

[0176] Each projection assembly 108 further includes an optical coupling assembly 164 that couples light from a respective scanning device 152 into a respective eyepiece 110. The optical coupling assembly 164 includes a collimation element 166 that collimates the light emitted by the scanning device 152 into a collimated light beam 200. Although the collimation element 166 is illustrated in FIG. 7 as being physically separate from the optical fiber 154, the collimation element is described in “Microlens Collimator for Scanning Optical Fiber in Virtual / Augmented Reality” in US Pat. No. 6,393,621, and US Pat. The optical coupling subsystem 164 may be physically mounted to the distal end 154b of each optical fiber 154 in a "microlens" arrangement, as described in U.S. patent application Ser. No. 15 / 286,215, entitled "Microlens Coupling System," expressly incorporated herein by reference. The optical coupling subsystem 164 further comprises an internal coupling element (ICE) 168, such as one or more reflective surfaces, diffraction gratings, mirrors, dichroic mirrors, or prisms, to optically couple the light into the end of the individual eyepieces 110.

[0177] Each eyepiece 110 takes the form of a waveguide device 170 including a planar optical waveguide 172 and one or more diffractive optical elements (DOEs) 174 associated with the planar optical waveguide 172. In an alternative embodiment, the waveguide device 170 may comprise a plurality of planar optical waveguides 172 and DOEs 174 each associated with a planar optical waveguide 172.

[0178] As best illustrated in FIG. 8, the planar optical waveguide 172 has a first end 176a and a second end 176b opposite the first end 176a along a length 178 of the planar optical waveguide 172. The planar optical waveguide 172 has a first face 180a and a second face 180b, where at least the first and second faces 180a, 180b (collectively, 180) form an internally reflective optical path (illustrated by solid arrows 182a and dashed arrows 182b, collectively, 182) at least partially along at least a portion of the length 178 of the planar optical waveguide 172. The planar optical waveguide 172 may take a variety of forms that provide substantial total internal reflection (TIR) ​​for light striking the face 180 at less than a defined critical angle.

[0179] The DOE 174 (illustrated in FIGS. 7 and 8 by double-dashed lines) may take a wide variety of forms to interrupt the TIR optical path 182 and provide multiple optical paths (illustrated by solid arrows 184a and dashed arrows 184b, collectively 184) between the interior 186 and exterior 188 of the planar optical waveguide 172, extending along at least a portion of the length 176 of the planar optical waveguide 172. In the illustrated embodiment, the DOE 174 can be characterized as an optical component comprising one or more diffraction gratings, each with a periodic structure on the order of the optical wavelength that splits and diffracts light into several beams traveling in different directions. The diffraction gratings can be composed of surface nano-bumps, nano-patterns, slits, etc., that can be photolithographically printed on a substrate, for example. The DOE 174 can provide positioning of the apparent object and the focal plane of the apparent object. This may be accomplished on a frame-by-frame, sub-frame-by-frame, or even pixel-by-pixel basis.

[0180] As illustrated in FIG. 8 , light propagates along the planar optical waveguide 172 with at least some reflection or “bounce” resulting from TIR propagation. Note that some embodiments may employ one or more reflectors in the internal optical path, such as, for example, thin films, dielectric coatings, metallic coatings, etc., that may enhance reflection. The light propagates along the length 178 of the planar optical waveguide 172 and intersects with the DOE 174 at various locations along the length 178. The DOE 174 may be incorporated within the planar optical waveguide 172 or abut or be adjacent to one or more of the faces 180 of the planar optical waveguide 172. The DOE 174 performs at least two functions. The DOE 174 shifts the angle of the light, causing a portion of the light to escape the TIR and emerge from the interior 216 outside the face 180 of the planar optical waveguide 172. The DOE 174 focuses the outcoupled light to a viewing distance. Thus, when viewed through face 180 of planar optical waveguide 172, a digital image is visible at one or more viewing distances.

[0181] A collimated light beam 200 entering the waveguide 172 at one of two different angles will follow one of two TIR optical paths 182a, 182b and result in light rays 202 exiting the planar optical waveguide 172 along one of two sets of external optical paths. That is, a collimated light beam 200a entering the waveguide 172 at an angle represented by TIR optical path 182a will result in light rays 202a exiting the planar optical waveguide 172 along the set of external optical paths, and a collimated light beam 200b entering the waveguide 172 at an angle represented by TIR optical path 182b will result in light rays 202b exiting the planar optical waveguide 172 along the set of external optical paths.

[0182] From the foregoing, it can be seen that the display subsystem 104 generates a series of composite image frames of pixel information that present a monocular image of one or more virtual objects to the user from each eyepiece 100. For example, with reference to FIG. 9, a composite image frame 250 is diagrammatically illustrated with cells 252a-252m divided into horizontal rows or lines 254a-254n. Each cell 252 of the frame 250 may define values ​​for each of a number of colors and / or intensities for the individual pixels to which the cell 252 responds. For example, the frame 250 may define, for each pixel, one or more values ​​for red 256a, one or more values ​​for green 256b, and one or more values ​​for blue 256c. The values ​​256 may be defined as a binary representation for each color, e.g., a separate 4-bit number for each color. Each cell 252 of the frame 250 may additionally include a value 256d that defines an amplitude.

[0183] Frame 250 may include one or more fields, collectively 258. Frame 250 may consist of a single field. Alternatively, frame 250 may comprise two or even more fields 258a-258b. The pixel information for a complete first field 258a of frame 250 may be defined before the pixel information for a complete second field 258b, e.g., occur before the pixel information for the second field 258b in an array, ordered list, or other data structure (e.g., record, linked list). Assuming the presentation subsystem is configured to handle more than two fields 258a-258b, a third or even fourth field may follow the second field 258b.

[0184] 10, a frame 250 is generated using a raster scan pattern 260. In the raster scan pattern 260, pixels 268 (only one is taken) are presented in succession. The raster scan pattern 260 typically presents pixels 268 from left to right (indicated by arrows 262a, 262b) and then from top to bottom (indicated by arrow 264). Thus, the presentation may start at the top right corner and traverse left across a first line 266a until the end of the line is reached. The raster scan pattern 260 typically then starts from the left on the next line below. The presentation may be temporarily blacked out or blanked out when returning from the end of one line to the beginning of the next line. This process is repeated line by line until the bottommost line 266n is completed, for example, at the bottom rightmost pixel 268. Once the frame 250 is completed, a new frame is started, again returning to the right of the topmost line of the next frame. Again, the presentation may be blanked while moving from the bottom left back to the top right to present the next frame.

[0185] Many embodiments of raster scanning employ what is referred to as an interlaced scan pattern. In an interlaced raster scan pattern, the lines from the first and second fields 258a, 258b are interlaced. For example, when presenting the lines of the first field 258a, pixel information for the first field 258a may be used for only the odd lines, while pixel information for the second field 258b may be used for only the even lines. Thus, all of the lines of the first field 258a of the frame 250 (FIG. 9) are typically presented before the lines of the second field 258b. The first field 258a may be presented using pixel information of the first field 258a to consecutively present line 1, line 3, line 5, etc. A second field 258b of frame 250 (FIG. 9) may then be presented following the first field 258a by using pixel information of the second field 258b to consecutively present line 2, line 4, line 6, etc.

[0186] 11, a spiral scan pattern 270 may be used in place of the raster scan pattern 260 to generate the frame 250. The spiral scan pattern 270 may consist of a single spiral scan line 272, which may be termed a coil or loop, and may include one or more complete angular cycles (e.g., 360 degrees). Similar to the raster scan pattern 260 illustrated in FIG. 10, pixel information in the spiral scan pattern 270 is used to define the color and / or intensity of each sequential pixel as an angular increment. An amplitude or radial value 274 defines the radial dimension from a starting point 276 of the spiral scan line 272.

[0187] 12, a Lissajous scan pattern 280 may alternatively be used to generate the frame 250. The Lissajous scan pattern 280 may consist of a single Lissajous scan line 282, which may be termed a coil or loop, and may include one or more complete angular cycles (e.g., 360 degrees). Alternatively, the Lissajous scan pattern 280 may include two or more Lissajous scan lines 282, each phase shifted relative to one another, nesting the Lissajous scan lines 282. Pixel information is used to define the color and / or intensity of each sequential pixel as an angular increment. An amplitude or radial value defines the radial dimension 284 from the start point 286 of the Lissajous scan line 282.

[0188] Referring to FIG. 13, a multi-field spiral scan pattern 290 may alternatively be used to generate the frame 250. The multi-field spiral scan pattern 290 includes two or more distinct spiral scan lines, collectively 160, specifically, four spiral scan lines 292a-160d. The pixel information for each spiral scan line 292 may be defined by a separate field of the frame. Advantageously, multiple spiral scan lines 292 may be nested simply by shifting the phase between each successive one of the spiral scan lines 292. The phase difference between the spiral scan lines 292 is a function of the total number of spiral scan lines 292 that will be employed. For example, four spiral scan lines 292a-292d may be separated by a 90-degree phase shift. An exemplary embodiment may operate at a 100Hz refresh rate with ten distinct spiral scan lines (e.g., sub-spirals). Similar to the embodiment of FIG. 9, one or more amplitude or radial values ​​define a radial dimension 294 from a starting point 296 of a spiral scan line 292 .

[0189] Further details describing the display subsystem are set forth in U.S. Patent Application Serial No. 14 / 212,961, entitled "Display Subsystem and Method," and in U.S. Patent Application Serial No. 14 / 212,961, entitled "Planar Optical Waveguide Apparatus With Diffraction Elements(s) and Subsystem," also incorporated herein by reference. No. 14 / 696,347, entitled "Employing Same," which is incorporated herein by reference.

[0190] 14A-14E, different variations of the left eyepiece 110L will now be described. The left eyepiece 110L utilizes one or more diffractive optical elements (DOEs) to in-couple light from the separate projection subassembly 108, out-couple light to the left eye 52 of the end user 50, and out-couple light to the light-sensing assembly 122. The right eyepiece 110R operates in the same manner as the left eyepiece 110L, and therefore, it should be understood that the following disclosure regarding the left eyepiece 110L applies equally to the right eyepiece 110R.

[0191] As discussed above, the left eyepiece 110L takes the form of a waveguide device 170 that includes a rectangular shaped planar optical waveguide 172 having a temple-facing end 172a and a nose-facing end 172b, as illustrated in Figure 14A. As best shown in Figures 15 and 16, the waveguide 172 is a single unitary substrate or plane of optically transparent material such as, for example, glass, fused silica, acrylic, or polycarbonate, although in alternative embodiments the waveguide 172 may be comprised of separate distinct plates of optically transparent material bonded together in the same plane or in different planes.

[0192] The ICE 168 is embedded within face 180b of the waveguide 172 to receive the collimated light beam 200 from the projection assembly 108 into the waveguide 172 via face 180b, although in alternative embodiments the ICE 168 may be embedded on the other face 180a or even at the edge of the waveguide 172 to couple the collimated light beam 200 into the waveguide 172 as an incoupled light beam. In the illustrated embodiment, the ICE 168 is positioned at the temple-facing end 172a of the eyepiece 172L.

[0193] The DOE 174 is associated with the waveguide 172 (e.g., incorporated within the waveguide 172 or abutting or adjacent to one or more of the faces 180a, 180b of the waveguide 172) to two-dimensionally expand an effective exit pupil of a collimated light beam 200 optically coupled into the waveguide 172. To this end, the DOE 174 comprises one or more orthogonal pupil expansion (OPE) elements 174a (only one is shown in FIG. 14A ) adjacent the face 180b of the waveguide 172 to split the in-coupled light beam 200 into orthogonal light beams 201, and an exit pupil expansion (EPE) element 174b associated with the waveguide 172 to split each orthogonal light beam 201 into out-coupled light rays 202 exiting the face 180b of the waveguide 172 towards the eye 52 of the end user 50. In alternative embodiments in which the waveguide 172 is comprised of distinct plates, the OPE element 174 and the EPE element 174b may be incorporated into different plates of the waveguide 172.

[0194] OPE element 174a relays light along a first axis (vertical or y-axis in FIG. 14A) and expands the effective exit pupil of the light along a second axis (horizontal or x-axis in FIG. 14A). In particular, ICE 168 optically in-couples collimated light beam 200 for propagation within waveguide 172 along internal reflection optical path 204a (in this case along the horizontal or x-axis) via TIR, and in so doing repeatedly intersects with OPE element 174a. In the illustrated embodiment, the OPE element 174a has a relatively low diffraction efficiency (e.g., less than 50%) and comprises a series of diagonal diffractive elements (45 degrees relative to the x-axis) such that at each intersection with the OPE element 174a, a portion (e.g., greater than 90%) of the internally coupled light beam 200 continues to propagate within the waveguide 172 along an internally reflected optical path 204a via TIR, and the remaining portion (e.g., less than 10%) of the internally coupled light beam 200 is diffracted as an orthogonal light beam 201 that propagates within the waveguide 172 along an internally reflected optical path 204b via TIR (in this case along the vertical or y-axis) toward the EPE element 174b. Although the optical path 204b is described as being perpendicular or orthogonal to the optical path 204a, it should be understood that the optical path 204b may alternatively be oriented obliquely relative to the optical path 204a. Thus, the exit pupil of the collimated light beam 200 internally coupled into the waveguide device 170 is expanded vertically along the y-axis by the OPE element 174a by splitting the internally coupled light beam 200 into multiple orthogonal beams 201 propagating along parallel internal reflection optical paths 204b.

[0195] The EPE element 174b, in turn, further expands the effective exit pupil of the light along the first axis (the vertical or y-axis in FIG. 14A). In particular, like the OPE element 174a, the EPE element 174b has a relatively low diffraction efficiency (e.g., less than 50%) such that at each intersection with the EPE element 174b, a portion (e.g., greater than 90%) of each orthogonal light beam 201 continues to propagate along a respective internally reflected optical path 204b, and the remaining portion of each orthogonal light beam 201 is diffracted as an outcoupled light ray 202 that exits (along the z-axis) from the face 180b of the waveguide 172, as illustrated in FIGS. 15 and 16. That is, each time a light beam impinges on the EPE element 174b, a portion of it will be diffracted toward the face 180b of the waveguide 172, while the remaining portion will continue to propagate along the respective internally reflected optical path 204b.

[0196] Thus, by splitting each orthogonal light beam 201 into multiple outcoupled light rays 202, the exit pupil of the internally combined light beam 200 is further expanded vertically along the y-axis by EPE element 174b, resulting in a two-dimensional array of outcoupled light rays 202 that resembles a larger version of the original internally combined light beam 200.

[0197] In addition to out-coupling light beamlets from face 180b of waveguide 172, EPE element 174b also serves to focus the output set of light beamlets along a given focal plane such that a portion of an image or virtual object is seen by end user 50 at a viewing distance that coincides with that focal plane. For example, if EPE element 174b only had a linear diffraction pattern, then the out-coupled light rays 202 exiting face 180b of waveguide 172 toward end user's 50's eye 52 would be approximately parallel, as shown in FIG. 17a, which would be interpreted by end user's 50's brain as light from a viewing distance (focal plane) at optical infinity. However, if the EPE element 174b has both linear and radially symmetric diffraction pattern components, the outcoupled light rays 202 exiting the face 180b of the waveguide 172 will be rendered more divergent from the perspective of the eye 52 of the end user 50 (e.g., a convex curvature will be imparted on the optical wavefront), requiring the eye 52 to accommodate to a closer distance in order to focus the resulting image on the retina, and will be interpreted by the brain of the end user 50 as light from a viewing distance closer to the eye 52 than optical infinity (e.g., 4 meters), as shown in FIG. 17b. The outcoupled light rays 202 exiting face 180b of waveguide 172 will be rendered even more divergent from the perspective of eye 52 of end user 50 (e.g., a more convex curvature will be imparted on the optical wavefront) and may require eye 52 to accommodate to an even closer distance in order to focus the resulting image on the retina, and will be interpreted by the brain of end user 50 as light from a viewing distance closer to eye 52 (e.g., 0.5 meters), as shown in FIG. 17c.

[0198] Although the left eyepiece lens 110L is described herein as having only one focal plane, it should be understood that multiple planar optical waveguides 172 with associated OPE elements 174a and EPE elements 174b can be used simultaneously, or in parallel, to generate images at multiple focal planes, as discussed in U.S. Patent Publication Nos. 2015 / 0309264 and 2015 / 0346490, which are expressly incorporated herein by reference.

[0199] 14A , the eyepiece 110L may be utilized to extract light intended for the eye 52 of the end user 50 directly by including an out-coupling element (e.g., DOE) 190. Thus, the light exits the eyepiece 110 at a location that is outside the field of view of the end user 50 and different from the location at which the light rays 202 exit the eyepiece 110 and thus represent the light rays 202 exiting the eyepiece 110. As will be explained in more detail below, a parameter indicative of the misalignment between the displayed left and right monocular images is derived from the light out-coupled from the eyepiece 110. In the illustrated embodiment, the out-coupling DOE 190 is positioned at the nose-facing end 172b of the eyepiece 172L.

[0200] In operation, some light emitted by the projection subsystem 108 intended for the left eye that is in-coupled into the eyepiece 110L (via the ICE 168) may track back through the region of the OPE element 174a and reach the out-coupled DOE 190. The out-coupled DOE 190 thus out-couples a portion of the in-coupled light beam 200 as a representative out-coupled ray 203 that exits the face 180b of the waveguide 172 (along the z-axis) toward the light sensor assembly 122, as illustrated in FIG. 15. In the illustrated embodiment, the substrate 170 includes a tab 173 on which the out-coupled DOE 190 is mounted. Preferably, the tab 173 of the substrate 170 is outside the field of view of the end user 50, such that light exiting the DOE 190 cannot be visualized by the end user 50.

[0201] 14B, another left eyepiece 110L is similar to the left eyepiece 110L illustrated in FIG 14A, except that the OPE element 174a and the EPE element 174b are clocked 90 degrees from each other, e.g., the EPE element 174 is located between the OPE element 174a and the nose-facing end 172b of the substrate, instead of below the OPE element 174 as illustrated in FIG 14A. Similar to the left eyepiece 110L illustrated in FIG 14A, the OPE 174a and the EPE element 174b expand in two dimensions the effective exit pupil of the collimated light beam 200 that is optically coupled into the waveguide 172 via the ICE 168. That is, the OPE element 174a splits the internally coupled light beam 200 into orthogonal light beams 201, and the exit pupil expansion (EPE) element 174b splits each orthogonal light beam 201 into externally coupled light rays 202 that exit the face 180b of the waveguide 172 toward the eye 52 of the end user 50.

[0202] OPE element 174a relays light along a first axis (the horizontal or x-axis in FIG. 14B) and expands the effective exit pupil of the light along a second axis (the vertical or y-axis in FIG. 14B). In particular, ICE 168 optically internally couples collimated light beam 200 for propagation within waveguide 172 via TIR along internally reflective optical path 204a (in this case along the horizontal or x-axis), and in so doing repeatedly intersects with OPE element 174a. In the illustrated embodiment, the OPE element 174a has a relatively low diffraction efficiency (e.g., less than 50%) and comprises a series of diagonal diffractive elements (45 degrees to the x-axis) such that at each point of intersection with the OPE element 174a, a portion (e.g., greater than 90%) of the internally coupled light beam 200 continues to propagate within the waveguide 172 along internal reflective optical path 204a via TIR, and the remaining portion (e.g., less than 10%) of the internally coupled light beam 200 is diffracted via TIR as an orthogonal light beam 201 that propagates within the waveguide 172 along internal reflective optical path 204b (in this case along the vertical or y-axis) and then along internal reflective path 204a (in this case along the horizontal or x-axis) towards the EPE element 174b. Thus, by splitting the internally coupled light beam 200 into multiple orthogonal beams 201 propagating along parallel internally reflective optical paths 204b, the exit pupil of the collimated light beam 200 internally coupled into the waveguide device 170 is expanded vertically along the y-axis by the OPE element 174a.

[0203] The EPE element 174b thus further expands the effective exit pupil of the light along the first axis (horizontal or x-axis in FIG. 14B). In particular, like the OPE element 174a, the EPE element 174b has a relatively low diffraction efficiency (e.g., less than 50%) such that at each point of intersection with the EPE element 174b, a portion (e.g., greater than 90%) of each orthogonal light beam 201 continues to propagate along a separate internally reflective optical path 204a, and the remaining portion of each orthogonal light beam 201 is diffracted as an outcoupled light ray 202 that exits the face 180b of the waveguide 172 (along the z-axis), as illustrated in FIGS. 18 and 19. That is, each time a light beam strikes the EPE element 174b, a portion of it will be diffracted toward the face 180b of the waveguide 172, while the remaining portion will continue to propagate along the separate internally reflective optical path 204b.

[0204] Thus, by splitting each orthogonal light beam 201 into multiple outcoupled light rays 202, the exit pupil of the internally combined light beam 200 is further expanded horizontally along the x-axis by EPE element 174b, resulting in a two-dimensional array of outcoupled light rays 202 that resembles a larger version of the original internally combined light beam 200.

[0205] 14A, the eyepiece 110L in FIG. 15 may be utilized to extract light intended for the eye 52 of the end user 50 directly by including an out-coupling DOE 190 at the nose-facing end 172b of the eyepiece 172L. However, instead of propagating only through the region of the OPE element 174, some light emitted by the projection subsystem 108 intended for the left eye that is in-coupled into the eyepiece 110L (via the ICE 168) may trace and propagate through the regions of both the OPE element 174a and the EPE element 174b to reach the out-coupling DOE 190. The out-coupling DOE 190 thus out-couples a portion of the in-coupled light beam 200 as a representative out-coupled ray 203 that exits the face 180b of the waveguide 172 toward the light sensor assembly 122 (along the z-axis), as illustrated in FIG. In the illustrated embodiment, the substrate 170 includes a tab 173 on which the out-coupling DOE 190 is mounted. Preferably, the tab 173 of the substrate 170 is outside the field of view of the end user 50 such that light exiting the DOE 190 cannot be visualized by the end user 50. In some embodiments, the functionality of the DOE 190 may be provided using an out-coupling prism.

[0206] 14A and 14B as non-overlapping in the xy plane, it should be noted that the OPE elements 174a and EPE elements 174b may overlap each other, fully or at least partially, in the xy plane. For example, as illustrated in FIG. 14C, another left eyepiece 110L is similar to the left eyepiece 110L illustrated in FIG. 14A and 14B, but the waveguide 172 is triangularly shaped and the OPE elements 174a and EPE elements 174b are disposed on opposite sides of the waveguide 172. As another example, as illustrated in FIG. 14D, yet another left eyepiece 110L is similar to the left eyepiece 110L illustrated in FIG. 14A and 14B, but the waveguide 172 is irregularly shaped, and the OPE element 174a and the EPE element 174b are disposed on opposite sides of the waveguide 172, respectively. The arrangement of the OPE elements 174a and the EPE elements 174b in FIG. 14C and 14D may be collectively referred to herein as DOEs 174a-b. In some embodiments, the functionality of the OPE element 174a and the EPE element 174b may be provided using a single DOE. Also, as yet another example, as illustrated in FIG. 14E, yet another left eyepiece 110L is similar to the left eyepiece 110L illustrated in FIG. 14D, but the DOEs 174a-b are further configured to outcouple light toward the light sensor assembly 122. For this reason, the eyepiece 110L of FIG. 14E does not need to include a dedicated out-coupled DOE, such as the out-coupled DOE 190 described above with reference to FIGS. 14A-14D. In the embodiment of FIG. 14E, the DOEs 174a-b of the left eyepiece 110L extend continuously into the nose-facing end 172b of the waveguide 172. Thus, at least a portion of the DOEs 174a-b of the left eyepiece 110L of FIG. 14E may be positioned outside the FOV of the end user 50. In some embodiments, such portions of the DOEs 174a-b may be physically hidden by one or more portions of a frame or housing structure, such as one or more of those described herein with reference to FIGS. 20-22B, 30, and 32A-32B.

[0207] 21, one embodiment of the frame structure 102, the display subsystem 104, and the light-sensing assembly 122 will now be described. In the illustrated embodiment, the frame structure 102 has a relatively lightweight, thin, and flexible form factor, for example in the shape of a magnifying glass or sunglasses, facilitating transportation, comfort, and a more aesthetically pleasing appearance. The frame structure 102 comprises a frame 300 for carrying the respective left and right eyepieces 110L, 110R, as well as respective left and right projection subassemblies 108L, 108R associated with the respective left and right eyepieces 110L, 110R, a pair of left and right temple arms 302L, 302R, a bridge 304 between the temple arms 302L, 302R, and a nose piece 306 affixed to the bridge 304. The frame structure 102 also carries forward-facing left and right sensors 103 L, 103 R in the form of video cameras for detecting the position and movement of the head 54 of the end user 50 .

[0208] In the illustrated embodiment, the frame 300, arms 302L, 302R, and bridge 304 are monolithically integrated together, but in alternative embodiments, any of these components may be comprised of discrete parts that are then integrated together using suitable interface contact components, such as bonding materials or fasteners. The temple arms 302L, 302R are designed to engage the respective temples of the head 54 of the end user 50 and maintain the frame 300, and thus the left and right eyepieces 110L, 110R, in front of the eyes 52 of the end user 50. The temple arms 302L, 302R may include left and right hinges 308L, 308R, respectively, to facilitate flexing of the arms 302L, 302R to properly fit the frame structure 102 to the head 54 of the end user 52. The nose pad 306 is configured to rest on the nose of the end user 52 when the frame structure 102 is worn, improving comfort for the nose and temples. Nose pad 306 may have a convex surface that conforms to the shape of the nose of end user 52 for added comfort.

[0209] The frame 300 includes left and right cantilevered arms 310L, 310R, each having a cantilever arm portion 312 extending away from the bridge 304 and an attachment arm portion 314 extending from the respective cantilever arm portion 312 in a plane parallel to the plane of the eye 52 of the end user 52. The left and right eyepieces 110L, 110R, respectively, are affixed to the attachment arm portion 314 in a suitable manner, and the left and right projection subassemblies 108L, 108R, respectively, are affixed to outer ends of the attachment arm portion 314 to facilitate introduction of light beams into the left and right eyepieces 110L, 110R, respectively, such that light rays exit the left and right eyepieces 110L, 110R, respectively, and left and right monocular images are displayed to the end user 50 as binocular images. In some embodiments, the left and right hinges 308L, 308R and / or the left and right temple arms 302L, 302L may be affixed directly to the left and right distal ends of the arm portion 314. The left and right eyepieces 110L, 110R as shown in FIG. 20 may be the same as or similar to the left and right eyepieces 110L, 110R as described above with reference to FIGS. 14A-14D. Thus, the left and right eyepieces 110L, 110R comprise left and right ICEs (not shown in Figures 20 and 21) configured to receive / in-couple light emitted from the two projection subsystems 108L, 108R, respectively, as described above, left and right out-coupling DOEs 190L, 190R, respectively, configured to out-couple light towards the light-sensing assembly 122, and one or more additional DOEs (not shown in Figures 20 and 21) configured to provide OPE and / or exit pupil extended EPE functionality.

[0210] In some examples, the left and right eyepieces 110L, 110R as shown in Figure 20 may be the same as or similar to the left and right eyepieces 110L, 110R as described above with reference to Figure 14E. Thus, the left and right eyepieces 110L, 110R may each comprise an ICE configured to receive / in-couple light emitted from a respective one of the projection subsystems 108L, 108R, and a DOE 174a-b (not shown in Figures 20 and 21) configured to provide OPE and / or exit pupil extended EPE functionality and out-couple light towards the light-sensing assembly 122. As discussed above with reference to Figures 14C and 14D, the DOE 174a-b may take the form of one or more DOE components.

[0211] 20, light that is coupled out of eyepiece 110L through outcoupling DOE 190 may propagate in free space before reaching light-sensing assembly 122. As described above, right eyepiece 110R may be implemented with an optical architecture similar to that of left eyepiece 110L (e.g., a mirror image version of the optical architecture of left eyepiece 110L). Thus, light that is coupled out of eyepiece 110R through a separate outcoupling DOE may propagate in free space before reaching light-sensing assembly 122 described above.

[0212] The light-sensing assembly 122 may be centrally mounted, and in the illustrated embodiment is affixed to the front surface of the bridge 304 so as to measure light from both the left and right eyepieces 110L, 110R. The light-sensing assembly 122 thus senses light rays emerging from the left and right DOEs 190L, 190R of the respective left and right eyepieces 110L, 110R, as will be described in further detail below.

[0213] 20, the frame structure 102, the light-sensing assembly 122, and the eyepieces 110L, 110R are configured such that the light-sensing assembly 122 is optically coupled to both the left and right eyepieces 110L, 110R, but rigidly (physically) decoupled from the left eyepiece 110L and the right eyepiece 110R. In other words, the portion of the frame structure 102 relative to which the light-sensing assembly 122 is mounted or positioned is movably or flexibly coupled to the portion of the frame structure 102 by which the left and right eyepieces 110L, 110R are carried or otherwise supported (e.g., the cantilevered arms 310L, 310R). In some embodiments, the portion of the frame structure 102 relative to which the light-sensing assembly 122 is mounted or positioned is itself relatively rigid so as to minimize local deformation and form a monolithic structure with the light-sensing assembly 122. Thus, by being rigidly decoupled / flexibly coupled to the eyepieces 110L, 110R, but mounted on a portion of the frame structure 102 that resides between and physically bridges the two eyepieces 110L and 110R, the light-sensing assembly 122 can be essentially independent of relative deformations between the two eyepieces 110L, 110R. Thus, the light-sensing assembly 122 is highly suitable for objectively observing light coupled out of the out-coupled DOEs 190L, 190R for purposes of binocular deformation analysis and / or online virtual image calibration.

[0214] 22A and 22B, the operation of the virtual image generation system 100 is shown when the frame structure 102 is in a mechanically ideal condition ("State A") such that the left and right eyepieces 110L, 110R are relatively aligned and therefore configured to present (e.g., to a user of the virtual image generation system 100) a binocularly matchable virtual image, and when the frame structure 102 is in a sub-ideal physical (deformation) condition (e.g., as a result of wear from use, thermal effects, etc.) such that the left and right eyepieces 110L, 110R are misaligned relative to one another ("State B"). Furthermore, it has been found that the virtual content does not move predictably with respect to any physical components, including the eyepieces. Rather, the virtual image behavior is a function of the interior of the light generator (e.g., the projection subsystem) and the light generator-eyepiece interface (e.g., the positioning of the projection subsystem relative to the ICE) and thermal and other effects.

[0215] 22A, in state A, the virtual image generation system 100 operates to display a virtual monocular image through both the left and right eyepieces 110L, 110R. That is, the projection subsystem 108L projects light representing virtual content toward the left eyepiece 110L, which in turn directs this light toward a DOE configured to in-couple (e.g., through an ICE) and provide OPE and / or EPE functionality, such as OPE 174a and EPE 174b described above. As it traverses the DOE, most of the directed light may exit the eyepiece 110L (e.g., directed toward the user's left eye), while some of this light continues toward the out-coupled DOE 190L, where it is coupled out of the eyepiece 110L as light (represented by light ray 203) and may be intercepted, at least in part, by the light-sensing assembly 122. The projection subsystem 108R, together with the right eyepiece 110R and its DOEs (e.g., externally coupled DOE 190, ICE, OPE 174a, and EPE 174b, etc.), may operate in a similar manner as in state A to present virtual content (e.g., to the user's right eye) and also to externally couple (e.g., through the externally coupled DOE 190R) and direct light representing the virtual content to the light-sensing assembly 122.

[0216] 22B, it can be seen that in state B, the left and right eyepieces 110L, 110R are at least rotationally misaligned with respect to one another about the yaw axis. As a result of this deformation (in this case caused by the cantilever support of arm portion 312 of right cantilevered arm 310R), it can also be seen that the angle at which light (represented by light ray 203) exits outcoupling DOE 190R of right eyepiece 110R in state B is different from the angle at which light (represented by corresponding light ray 203) exits outcoupling DOE 190R of right eyepiece 110R in state A, and also different from the angle at which light (represented by light ray 203) exits outcoupling DOE 190L of left eyepiece 110L in both states A and B. Due to the optical capabilities of the optical sensing assembly 122, the virtual image generation system 100 may be able to detect such deformation / relative misalignment between the two eyepieces 110L, 110R based on the data output from the optical sensing assembly 122.

[0217] As briefly discussed above, by detecting light exiting both DOEs 190L, 190R, the light-sensing assembly 122 may sense at least a first parameter indicative of a misalignment between the left and right monocular images presented as binocular images by the respective left and right eyepieces 110L, 110R. The control circuitry (e.g., CPU 114) of the virtual image generation system 100 may receive and process data representative of such measurements made by the light-sensing assembly 122. The control circuitry of the virtual image generation system 100 may operate to effectively compare data derived from light incident on the light-sensing assembly 122 when the frame structure 102 is in state A with data derived with respect to light incident on the light-sensing assembly 122 when the frame structure 102 is in state B, and subsequently quantify, characterize, or otherwise detect the relative deformation state of the left and right eyepieces 110L, 110R.

[0218] In response to detecting a relative misalignment of the left and right eyepieces 110L, 110R about one or more rotational axes (e.g., pitch, roll, and / or yaw), the virtual image generation system 100 may perform one or more online virtual image calibration operations to present a binocularly matchable virtual image (e.g., to a user of the virtual image generation system 100) or otherwise compensate for such misalignment. As described above, such calibration routines may include updating translation and / or rotation parameters stored for the eyepieces 110L, 110R. The virtual image may be virtually calibrated by the GPU 116 or other components of the control subsystem of the virtual image generation system 100. In particular, such updated translation and / or rotation parameters may be utilized to translate, rotate, or otherwise transform one or more extrinsic parameters of a “virtual camera” (also referred to as a “rendering camera”) in a rendering space or a “virtual screen” associated therewith. In some examples, one or more intrinsic parameters of the rendering camera may be adjusted based on the detected binocular misalignment. Further details discussing the creation, adjustment, and use of the rendering camera in the rendering process are provided in U.S. Patent Application No. 15 / 274,823 and U.S. Patent Application No. 16 / 250,931, both of which are expressly incorporated by reference in their entirety herein for all purposes.

[0219] In some embodiments, one or more rendering cameras may be employed for each eye of the user. Thus, in some of these embodiments, the virtual image generation system 100 may employ a first rendering camera associated with the left eyepiece 110L and a second rendering camera associated with the right eyepiece 110R. To address misalignment of the left and right eyepieces 110L, 110R about the pitch, roll, and / or yaw axes, the virtual image generation system 100 may, for example, make one or more adjustments to the orientation of one or both of the first and second rendering cameras about the pitch, roll, and / or yaw axes, respectively. For example, to compensate for a misalignment about the pitch axis similar to that shown in FIG. 4B, the virtual image generation system 100 may make one or more adjustments to rotate or tilt the second rendering camera downward about the pitch axis, rotate or tilt the first rendering camera upward about the pitch axis, or a combination thereof. Alternatively or in addition, the virtual image generation system 100 may perform one or more operations to translate the virtual image presented on the right eyepiece 110R vertically downward, translate the virtual image presented on the left eyepiece 110L vertically upward, or both, to compensate for a misalignment about the pitch axis similar to that shown in FIG. 4B. Similarly, to compensate for a misalignment about the roll axis similar to that shown in FIG. 4C, the virtual image generation system 100 may perform one or more adjustments to rotate or tilt the second rendering camera clockwise about the roll axis, rotate or tilt the first rendering camera counterclockwise about the roll axis, or a combination thereof. Furthermore, to compensate for a misalignment about the yaw axis similar to that shown in FIG. 4D, the virtual image generation system 100 may perform one or more adjustments to rotate or tilt the second rendering camera left about the yaw axis, rotate or tilt the first rendering camera right about the yaw axis, or a combination thereof.Alternatively, or in addition, virtual image generation system 100 may perform one or more operations to horizontally translate the virtual image presented on right eyepiece 110R to the left, horizontally translate the virtual image presented on left eyepiece 110L to the right, or both to compensate for misalignment about the yaw axis, similar to that shown in FIG. 4D. To compensate for misalignment about multiple axes, virtual image generation system 100 may make a combination of rotational and / or translational adjustments to one or both of the first and second rendering cameras and / or the left and right virtual images. In some embodiments, virtual image generation system 100 may operate on a feedback loop to make fine or incremental adjustments to the orientation and / or position of one or both of the first and second rendering cameras and / or the left and right virtual images until a desired result is achieved.

[0220] In some embodiments, the virtual image generation system 100 may store a calibration profile for the two eyepieces 110L, 110R, including a relative translation parameter and a relative rotation parameter. The relative translation parameter may correspond to a relative distance between the respective centers of gravity of the two eyepieces 110L, 110R, and the relative rotation parameter may correspond to a relative angular orientation between the two eyepieces 110L, 110R. In some examples, the relative translation parameter may correspond to a distance between an apex of a display alignment volume of the eyepiece 110L and an apex of a display alignment volume of the eyepiece 110R. Similarly, in some of these examples, the relative rotation parameter may correspond to a relative angular orientation between a display alignment volume of the eyepiece 110L and a display alignment volume of the eyepiece 110R. Additional information regarding examples of display alignment volumes and associated systems and techniques is provided in U.S. patent application Ser. No. 16 / 251,017, the entirety of which is incorporated herein by reference.

[0221] In one embodiment, the image misalignment parameters sensed by the light-sensing assembly 122 include the angle at which the light beam 203 exits the respective left and right eyepieces 110L, 110R. To this end, the light-sensing assembly 122 includes two discrete sensors (not shown) for independently sensing the light beam 203 exiting the respective left and right DOEs 190L, 190R. In the illustrated embodiment, the light-sensing assembly 122 senses a parameter indicative of the angle of the light beam 203 relative to one or more reference planes. For example, these reference planes may include an xz plane, a yz plane, and an xy plane, as described in further detail below. It should be noted that although these reference planes may be flat, the outer surfaces of each of the left and right eyepieces 110L, 110R may alternatively be curved, and therefore these reference planes may also be curved.

[0222] Also, as briefly mentioned above, the angle of the exiting light ray is highly correlated with the position of the pixel in the image frame. For example, as illustrated in Figures 23A and 23B, a collimated light beam 200 from one of the projection subsystems 108 enters an individual eyepiece 110 via the ICE 168 and propagates within the waveguide 172. The exit pupil of the propagating light beam 200 is expanded along the x-axis and y-axis by the DOE 174, as described above with respect to the light ray 202 exiting the face 180b of the waveguide 172 in Figures 14A-14E and 15-19. Although only one light ray 202 corresponding to the collimated light beam 200 input into the eyepiece 110 is shown for purposes of simplicity, it should be understood that there will typically be many light rays 202 exiting the eyepiece 110 corresponding to the single collimated light beam 200, with all angles of the exiting light rays 202 relative to the scan angle of the collimated light beam 200.

[0223] The collimated light beam 200 is scanned by the projection subsystem 108 to generate an input cone of light 210a, with each beam angle within the cone corresponding to a pixel 212 within the user's field of view (FOV) 214. As shown in FIG. 23A, when the collimated light beam 200 has one particular beam angle, a corresponding pixel 212a is generated within the lower left region of the FOV 214, while when the collimated light beam 200 has another particular beam angle, a corresponding pixel 212b is generated within the upper right region of the FOV 214. The eyepiece 110 presents an xy image plane to the end user 50 by transmitting the input light cone 210a to the exit face 180b of the waveguide 172, resulting in an output cone of light 210b.

[0224] For each of the two eyepieces 110L, 110R, the CPU 114 (shown in FIG. 5) generates monocular image data which, in addition to defining pixel color and intensity, defines the location of pixels in the monocular image for the respective eyepiece 110, and thus the relative design angles of the exiting light rays 202 corresponding to the defined locations of the same pixels for both eyepieces 110L, 110R, and the actual relative angles of the exiting light rays 202 for both eyepieces 110L, 110R as sensed by the light sensing assembly 122. Based on this, the angle of the light beam 200 generated by the projection subsystem 108 relative to the individual eyepieces 110 is controlled, thereby ensuring that the actual relative angles of the exiting light rays 202 of the eyepieces 110L, 110R are approximately the same as the designed relative angles of the exiting light rays 202 of the eyepieces 110L, 110R, i.e., that the pixels of the monocular images produced by the eyepieces 110L, 110R match as closely as possible so that the end user 50 correctly perceives the matching monocular images as binocular images.

[0225] For example, referring to FIG. 24, the orientation of an outgoing ray 202 from an origin in three-dimensional space may be defined by two angles, one on the xz plane 216a and another on the yz plane 216b, that closely correspond to the individual x- and y-coordinates of a pixel 212 in the xy plane of the FOV 214. The CPU 114 may determine the actual angles of the exiting rays 202 in the xz and yz planes 216a, 216b for each of the left and right eyepieces 110L, 110R based on the parameters sensed by the light sensing assembly 122, calculate the deviation between the actual angles of the exiting rays 202 and the designed angles of the exiting rays 202 for each corresponding pixel 212 of the eyepieces 110L, 110R, and modify the operation of the projection subsystem 108 to compensate for the difference between the relative actual angles of the exiting rays 202 and the relative designed angles of the exiting rays 202 for the eyepieces 110L, 110R to match the monocular images generated by the eyepieces 110L, 110R.

[0226] To correct such discrepancies, the CPU 114 may instruct the projection subsystem 108 to adjust the scanning position of the collimated light beam 200 for one or both of the eyepieces 110L, 110R. In the illustrated embodiment, the scanning position of the collimated light beam 200 for the individual eyepieces 110 may be adjusted by modifying the actuation / drive profile (e.g., drive voltage, drive signal, drive pattern, etc. provided by the drive electronics 162 of the piezoelectric elements 160) of the scanning device 156 (see FIG. 7) such that the mechanical response of the scanning device 156 more closely matches the desired mechanical response for the desired pixel location. As another example, the CPU 114 may modify the monocular image data for the individual eyepiece 110L (e.g., by modifying pixel modulation / pixel synchronization) to compensate for a known misalignment between the left and right monocular images for the eyepieces 110L, 110R. In this case, the "incorrect angle" of the exiting light beam 203 is measured but not corrected. As yet another example, a combination of modifying the scan position of the collimated light beam 200 and modifying the image data may be employed by the CPU 114 .

[0227] The scanning position of the collimated light beam 200 and / or monocular image data for one or both of the eyepieces 110L, 110R can be corrected to compensate for misalignments between the relative actual angles of the exiting rays 202 of the eyepieces 110L, 110R and the desired angles of the exiting rays 202 of the eyepieces 110L, 110R by employing a software / hardware controller (e.g., similar to a proportional-integral-derivative (PID)) that monitors the angle measurements in real time and effects corresponding adjustments to one or both of the projection subsystems 108 as quickly as possible, minimizing delays due to processing and causality. Alternatively, because the display subsystem 104 is an iterative system in which the same target scanning pattern is used to generate each image frame, the angle measurements obtained for the previous image frame can be calculated and stored, and then corrections can be applied to the subsequent image frame. In the presence of high image frame rates, delays of the order of milliseconds can be incurred.

[0228] For each left and right eyepiece 110L, 100R, the light sensing assembly 122 detects the intensity of at least one of the light rays 202 relative to the xz and yz planes 216a, 216b. In the embodiment illustrated in Figures 14A-14E and 15-19, the sensing assembly 122 measures the intensity of at least one light ray 203 (only one is described herein) that represents the light rays 202 exiting or emanating from the respective eyepiece 110. In this embodiment, the representative light ray 203 is different from the exiting light ray 202 and exits the out-coupled DOE 190 of the respective eyepiece 110 at a different location than the exiting light ray 202, preferably outside the FOV 214 of the end user 50.

[0229] In one embodiment, the light-sensing assembly 122 comprises two separate and independent sensor arrays for separately detecting light emerging from the left and right DOEs 190L, 190R of the left and right eyepieces 110L, 110R, respectively. In this case, it is important that the two sensor arrays are rigidly coupled to each other such that there is no deformation between the two sensor arrays to provide a stable platform from which to detect any misalignment between the left and right eyepieces 110L, 110R caused by deformation of the frame 300. An example of such a two-sensor array is described in more detail below with reference to Figures 31A-31B.

[0230] 25, the light-sensing assembly 122 includes a left non-imaging sensor array 220L for detecting the angle of the representative light ray 203 emerging from the left DOE 190L of the left eyepiece 110L, and a right non-imaging sensor array 220R for detecting the angle of the representative light ray 203 emerging from the right DOE 190R of the right eyepiece 110R. Each of the sensor arrays 220L, 220R includes a pair of orthogonal angle sensors 222a and 222b (collectively, 222) configured to sense orthogonal components of the representative light ray 203 emerging from the respective DOEs 190 of the eyepieces 110, and a normalization sensor 224 configured to sense the absolute intensity of the representative light ray 203 such that readings from the orthogonal angle sensors 222 can be normalized to the intensity of the light in the respective eyepieces 110. That is, when an image is generated, pixel intensities are modulated corresponding to the colors of the different pixels. Therefore, the pixel intensity modulation measured by the light intensity sensor 224 may be taken into account when interpreting the measurements of the angle sensor 222 .

[0231] 26A, the pair of angle sensors 222a, 222b each comprises a pair of light intensity sensors 226a, 226b (collectively, 226), a pair of angle-selective dielectric layers 228a, 228b (collectively, 228), and a pair of cylindrical lenses (e.g., GRIN lenses) 230a, 230b (collectively, 230). The GRIN lenses 230 directly face the DOE 190 of the respective eyepiece 110, the dielectric layers 228 are each mounted directly to an outwardly facing surface of the GRIN lenses 230, and the light intensity sensors 226 are each mounted directly to an outwardly facing surface of the dielectric layers 228.

[0232] Importantly, the directional nature of each dielectric layer 228 transmits light energy as a known function of the angle at which the light energy is incident on the plane of the dielectric layer 228 (which lies in the xy plane). For example, as can be seen from the exemplary dielectric layer transmission-angle relationship illustrated in FIG. 27A, the closer the angle of the representative light ray 203 is to normal to the plane of the dielectric layer 228 (0 degrees), the greater the energy of the representative light ray 203 that is transmitted to the light intensity sensor 226. Furthermore, each light intensity sensor 226 will generate a voltage that is a known function of the intensity of the light energy incident at an angle normal to the plane of the respective dielectric layer 228. For example, as can be seen from the exemplary photodetector intensity-voltage relationship illustrated in FIG. 27B, the greater the intensity of the light energy incident on the dielectric layer 228, the greater the voltage generated by the dielectric layer 228. As a result, the angle at which the representative light ray 203 is incident on the plane of the light intensity sensor 226 can be determined from these relationship curves, as will be described in more detail below. It should be noted that the relationship curves illustrated in Figures 27A and 27B may be generated analytically, or may be generated by measuring or calibrating the relevant values ​​per unit, thereby resulting in a more accurate and calibrated relationship curve.

[0233] Also, note that the projection of the sensor aperture onto a plane normal to the incident light may be utilized as a primary means of sensing the angle of the representative light ray 203 due to "cosine falloff," which reduces area the greater the angle of incidence of the incident light, and the optical physical properties of the light sensor; the light intensity sensor 226 itself may have some degree of angle dependence, in which case the angle sensor 222 may not include the dielectric layer 228, or may be utilized as a secondary or supplemental means of sensing the angle of the representative light ray 203 in addition to the use of the dielectric layer 228 in the angle sensor 222. In either case, a photodetector intensity-angle relationship (not shown) may be generated that correlates the voltage sensed by the individual light intensity sensor 226 with a range of light incidence angles. This photodetector intensity-angle relationship may itself be used to determine the angle of the representative light ray 203, or may be used to confirm the angle of the representative light ray 203 determined from the dielectric layer transmission-angle relationship (FIG. 27A) and the photodetector intensity-voltage relationship (FIG. 27B).

[0234] Notably, because the dielectric layer 228 is isotropic in nature in that it will transmit energy from the representative light ray 203 equally at the same angle of incidence but in different radial directions, the sensing assembly 122 breaks the circular symmetry of the dielectric layer 228, thereby allowing the orientation of the representative light ray 203 to be projected into the xz and yz planes 216a, 216b. To this end, the cylindrical lenses 230a, 230b are configured to pass first and second orthogonal components of the representative light ray 203 (corresponding to the xz and yz planes 216a, 216b) through respective dielectric layers 228a, 228b, respectively.

[0235] Thus, one lens 230a separates the energy of the representative ray 203a into a horizontal (x-) component, and the other lens 230b separates the energy of the representative ray 203b into a vertical (y-) component. Thus, one light intensity sensor 226a will receive only the horizontal energy component of the representative ray 203a exiting the DOE 190, and the other light intensity sensor 224b will receive only the vertical energy component of the representative ray 203b via the DOE 190. The angles of the representative ray 202 projected onto the xz and yz planes 216a, 216b can then be determined from these horizontal and vertical components of the representative ray 203, as discussed below.

[0236] It should be noted that although each angle sensor 222 is described as detecting one representative light ray 203 for purposes of simplicity and clarity in illustration, each angle sensor 222 will in fact detect many light rays, and thus the voltage output of the angle sensor 222 will represent a combination of the horizontal 203a or vertical 203b components of the representative light ray 203. However, the DOE 190 preferably has a linear diffraction pattern such that the angle of the representative light ray 203 exiting the DOE 190 is uniform given the specific angle of the incombined collimated beam 200.

[0237] In an alternative embodiment illustrated in Figure 26B, rather than using a cylindrical lens 230, the out-coupled DOE 190 itself may be compartmentalized into a portion that passes one orthogonal component to the angle sensor 222a and another portion that passes the other orthogonal component to the angle sensor 222b in the same manner as the cylindrical lens 230 described above. In yet another alternative embodiment illustrated in Figure 26C, the angle sensors 222 each comprise a pair of polarizing elements 232a, 232b (collectively, 232) configured to polarize the representative light beam 203 into orthogonally polarized light beams that are then passed through dielectric layers 228a, 228b to respective light intensity sensors 226a, 226b.

[0238] In yet another alternative embodiment, instead of a cylindrical lens or any of the other devices described above, the dielectric layers 228a, 228b themselves can be distorted into an orthogonal orientation such that the dielectric layers 228 are no longer isotropic, but rather are anisotropic and tend to pass more representative light rays 203 in one orthogonal direction than in the other orthogonal direction, and vice versa. Although the anisotropic dielectric layers 228 do not perfectly transmit the representative light rays 203 in an orthogonal manner, the angles of the representative light rays 203 when projected onto the xz and yz planes 216a, 216b can still be determined in light of the known orthogonal transmission coefficients of the dielectric layers 228 (i.e., the ratio of light energy transmitted by each dielectric layer 228 in one orthogonal direction relative to the other orthogonal direction).

[0239] It is noted that the angle sensor 220 as disclosed can only sense information that can provide the absolute angle of the outgoing light beam 203 in the xz plane 216a or the yz plane 216b (e.g., an absolute angle of 30° can be +30° or -30°). Thus, the sensing assembly 122 senses another parameter that indicates the relative angle of the outgoing light beam 203 in the xz plane 216a or the yz plane 216b. In the illustrated embodiment, this detected parameter comprises the quadrant into which the collimated light beam 200 is projected such that the sign of the angle of the light beam 203 projected onto the xz and yz planes 216a, 216b can be determined.

[0240] For example, as illustrated in Figure 28A, one output ray 203 forms an angle with respect to the xy plane 216c. That is, when projected onto the xy plane 216c, the output ray 203 may form an angle with the xy plane 216c, as illustrated in Figure 28B. As shown therein, the angle of the output ray 203 is projected into a second quadrant of the xy plane 216c, and thus, it can be determined that the angle that the output ray 203 makes in the xz plane 216a has a negative sign, and the angle that the output ray 203 makes in the yz plane 216b has a positive sign.

[0241] The sensing assembly 122 is configured to indirectly detect the quadrant into which the outgoing light ray 203 is projected by detecting the quadrant into which the collimated light beam 200 entering the ICE 168 from the collimation element 274 is directed (shown in FIG. 7). In particular, the sensing assembly 122 comprises one or more quadrant sensors (not shown), which may be mounted on the ICE 168 shown in FIGS. 14A-14E and 15-19. As shown in FIG. 29A, the four quadrant sensors 232 are spaced apart within the quadrants of the reference plane 234 such that activation of one of the sensors 232 by the collimated light beam 200 will indicate the quadrant into which the light beam 200 is currently directed. Alternatively, as shown in FIG. 29B, the sensing assembly 122 may comprise a quadrant position sensing detector (PSD) 236 centered at the intersection of the quadrants. In either case, since the angular position of the collimated light beam 200 is relative to the angle of the light ray 203 exiting the respective eyepiece lens 110, the quadrant into which the light ray 203 is projected in the xy plane 216c can be derived from the quadrant of the reference plane 234 into which the collimated light beam 200 is directed.

[0242] In an alternative embodiment, the quadrant into which the light beam 203 is projected in the xy plane 216c can be inferred simply from the quadrant of the current scan position within the scan pattern when the intensity of the emitted light beam 203 is sensed by the sensing assembly 122.

[0243] One method of determining the angles of the light rays 203 projected onto the xz plane 216a and yz plane 216b will now be described. Assume that the light intensity sensor 222 measures a voltage of 90mV. According to the exemplary photodetector intensity-voltage relationship illustrated in Figure 22b, the absolute intensity of the representative light ray 203 can then be determined to be 100nits.

[0244] Assume that the angle sensor 220a measures a voltage of 70 mV. According to the exemplary photodetector intensity-voltage relationship illustrated in FIG. 27B, the intensity of the representative light ray 203 transmitted by the angle-selective dielectric layer 226a to the light intensity sensor 224a can then be determined to be 80 nits. Therefore, based on the known intensity of the light ray of 100 nits, it can be determined that the dielectric layer 226a transmits 80 / 100=80% of the light energy to the light intensity sensor 224a. According to the exemplary dielectric layer transmission-angle relationship illustrated in FIG. 27A, the absolute angle of the representative light ray 203 projected onto the xz plane 216a can then be determined to be 20 degrees.

[0245] Similarly, assume that the angle sensor 220b measures a voltage of 65 mV. According to the exemplary photodetector intensity-voltage relationship illustrated in FIG. 27B, the intensity of the representative light ray 203 transmitted by the angle-selective dielectric layer 226b to the light intensity sensor 224b can then be determined to be 75 nits. Therefore, based on the known intensity of the light ray of 100 nits, it can be determined that the dielectric layer 226b transmits 75 / 100=75% of the light energy to the light intensity sensor 224b. According to the exemplary dielectric layer transmission-angle relationship illustrated in FIG. 27A, the absolute angle of the representative light ray 203 projected onto the yz plane 216a can then be determined to be 35 degrees.

[0246] If the sensor 232 or PSD 236 detects that the angle of the representative light ray 203 projected onto the xy plane 216c is within the third quadrant, or if the angle of the representative light ray 203 projected onto the xy plane 216c is otherwise known to be within the third quadrant derived from knowledge of the known scan angle of the collimated beam 200, then it can be determined that the angles of the representative light ray 203 projected into the xz plane 216a and yz plane 216b, respectively, are both negative and therefore should be -20 degrees and -35 degrees.

[0247] Although the light-sensing assembly 122 has been described as having two separate and independent sensor arrays for detecting light exiting from the respective left and right DOEs 170L, 170R of the left and right eyepieces 110L, 110R, in other embodiments, the light-sensing assembly 122 may have a single sensor array for detecting light exiting from both the left and right DOEs 170L, 170R of the left and right eyepieces 110L, 110R.

[0248] For example, referring now to FIG. 30, another light-sensing assembly 122′ carried by the frame structure 102 will be described. The light-sensing assembly 122′ comprises a single sensor 250, a planar optical waveguide 272, and a waveguide arrangement 270 including left and right internal coupling elements (ICEs) 268L, 268R and an external coupling DOE 290 associated with the planar optical waveguide 272. In some embodiments, the light-sensing assembly 122′ may be implemented as the light-sensing assembly 122 in one or more of the embodiments described above with reference to FIGS. 22A-22B. The planar optical waveguide 272 has a first end 276a and a second end 276b opposite the first end 276a along a length 278 of the planar optical waveguide 272. The planar optical waveguide 272 has a first face 280a and a second face 280b (collectively, 280) and forms an internally reflective optical path (illustrated by solid arrow 282) along at least a portion of the length 278 of the planar optical waveguide 272. The planar optical waveguide 272 may take a variety of forms that provide substantial total internal reflection (TIR) ​​for light that strikes the face 280 below a defined critical angle.

[0249] The left and right ICEs 268L, 268R are incorporated into face 280b of the waveguide 272 at opposite ends 276a, 276b of the waveguide 272 to receive the representative light rays 203 from the left and right outcoupled DOEs 170L, 170R of the left and right eyepieces 110L, 110R, respectively, although in alternative embodiments the ICEs 268L, 268R may be incorporated into the other face 180a or even edges of the waveguide 272 to couple the representative light rays 203 into the waveguide 272 as incoupled light beams. Light propagates along the planar optical waveguide 272 with at least some reflection or "bounce" resulting from TIR propagation. An out-coupling DOE 290, in contrast to the ICEs 268L, 268R, is incorporated into face 280a of waveguide 272 for out-coupling light as a representative light ray 203 emerging from face 180a of waveguide 272 towards single sensor 250.

[0250] The single sensor 250 can take one of the forms of the sensor array 220 illustrated in Figures 25-26 to sense the angle of the representative light ray 203 emerging from the left and right DOEs 190L, 190R of the left and right eyepieces 110L, 110R, respectively, in three dimensions. In this case, the angle detection can be time multiplexed such that the angle of the representative light ray 203 emerging from the left and right DOEs 190L, 190R of the left and right eyepieces 110L, 110R can alternatively be detected.

[0251] In another embodiment, the representative light rays 203 emerging from the left and right eyepieces 170L, 170R may form an interference pattern (Fourier transform of the projected image) on the surface of the sensor 250 that is a function of the angular location of the point source (e.g., pixel). Sensing such an interference pattern, inferring from it the observed points and comparing them to the intended angular locations of the points will give the relative pitch and yaw between the left and right eyepieces 170L, 170R. Roll can be determined by using three or more points from each of the two eyepieces 170L, 170R.

[0252] In other embodiments, imaging-based approaches may also be employed by the virtual image generating system 100, in which case the sensor 250 of the central sensing assembly 122' illustrated in FIG. 30 may include or take the form of one or more imaging devices (e.g., cameras, photodiodes, etc.) and one or more lensing elements (not shown) such that light exiting the left and right DOEs 190L, 190R of the left and right eyepieces 110L, 110R undergoes lensing and forms an image on the imaging sensor 250. Imaging-based approaches may employ conventional cameras and refractive lensing or "wafer" cameras integrated on a glass substrate. In such embodiments, the virtual image generating system 100 may be capable of detecting deformation / relative misalignment between the two eyepieces 110L, 110R based on images captured by one or more imaging devices. In some embodiments, the virtual image generation system 100 may detect deformations / relative misalignments between the two eyepieces 110L, 110R by evaluating images captured by one or more imaging devices against a virtual image as intended to be perceived through the left eyepiece 110L, a virtual image as intended to be perceived through the right eyepiece 110R, a fusion of the two aforementioned virtual images as intended to be perceived, or a combination thereof. In some examples, such imaging devices may also be configured to serve dual roles as forward-facing image sensors (e.g., camera 103) capable of capturing images of the “real world” (e.g., the environment in front of a user of the virtual image generation system 100).

[0253] Thus, the imaging sensor of the sensing assembly 122' obtains identical copies of the left and right monocular virtual images that are presented to the end user 50 via the left and right eyepieces 110L, 110R. Alternatively, the virtual image generation system 100 may project test monocular virtual images into the left and right eyepieces 110L, 110R (e.g., a few pixels outside the field of view of the end user 50) separately from the actual virtual images presented to the end user 50.

[0254] In either case, the control circuitry (e.g., CPU 114) of virtual image generation system 100 may receive and compare the monocular virtual image detected by sensing assembly 122' (as a representation of the monocular virtual image presented to end user 50 as a binocular image by eyepieces 110L, 110R) and determine whether a misalignment between the monocular images exists. In response to detecting a relative misalignment of left and right eyepieces 110L, 110R about one or more rotational axes (e.g., pitch, roll, and / or yaw), virtual image generation system 100 may perform one or more online virtual image calibration operations, as discussed above, to present (e.g., to a user of virtual image generation system 100) a binocularly matchable virtual image or otherwise compensate for such misalignment.

[0255] As mentioned above, in some embodiments, the light-sensing assembly 122 described herein may include a pair of sensing devices to detect light exiting from the respective left and right DOEs 170L, 170R of the left and right eyepieces 110L, 110R. For example, FIG. 31A depicts a front view of yet another light-sensing assembly 122″ for use in the virtual image generation system of FIG. 5. In some examples, the light-sensing assembly 122″ may be implemented as the light-sensing assembly 122 in one or more of the examples described above with reference to FIGS. 22A-22B. The light-sensing assembly 122″ includes left and right sensors 3150L, ​​3150R disposed on or within the body 3110.

[0256] The left and right sensors 3150L, ​​3150R may be optically coupled to the left and right eyepieces 110L, 110R, respectively, and may be rigidly coupled to each other via the body 3110. The left and right sensors 3150L, ​​3150R may take the form of, for example, cameras or other imaging devices configured to capture images. Thus, in some embodiments, the left and right sensors 3150L, ​​3150R may be configured to receive and image light outcoupled by the left and right eyepieces 110L, 110R, respectively, which may include light representing a monocular virtual image. For example, FIG. 31B depicts a perspective view of the optical sensor assembly 122″ of FIG. 31A in which the left and right sensors 3150L, ​​3150R receive and image the light rays 203 as coupled out from the left and right eyepieces 110L, 110R. As discussed above, the images captured by the left and right sensors 3150L, ​​3150R may be evaluated against left and right virtual images as intended to be perceived through the left and right eyepieces 110L, 110R, respectively, a fusion of the two aforementioned virtual images as intended to be perceived, or a combination thereof, to detect or measure deformations / relative misalignment between the two eyepieces 110L, 110R. In some embodiments, the virtual image generation system 100 may include the left and right sensors 3150L, ​​3150R ... Based on such evaluation of the images captured by 3150R, rotational and / or translational adjustments may be made to one or both of the two rendering cameras associated with the two eyepieces 110L, 110R, respectively, and / or to one or both of the two virtual images to be presented through the two eyepieces 110L, 110R, respectively. More specifically, the virtual image generation system 100 may evaluate the images captured by the left and right sensors 3150L, ​​3150R and identify and quantify differences between one or both of the images captured by the left and right sensors 3150L, ​​3150R and one or both of the left and right virtual images as intended to be perceived through the left and right eyepieces 110L, 110R.The virtual image generating system 100 may make one or more of the aforementioned adjustments, for example, based on the determined differences in the images. In some embodiments, the virtual image generating system 100 may perform one or more image processing operations to fuse or otherwise combine the images captured by the left and right sensors 3150L, ​​3150R, and then perform one or more operations to identify and quantify differences between the resulting combined image and the fusion of the left and right virtual images as intended to be perceived through the left and right eyepieces 110L, 110R. In such embodiments, the virtual image generating system 100 may make one or more of the aforementioned adjustments, for example, based on the determined differences in the images. In some examples, the left and right virtual images may correspond to test virtual monocular images. Such test virtual monocular images may correspond to, for example, a checkerboard pattern or other predetermined spatially varying pattern.

[0257] The body 3110 of the optical sensor assembly 122" may be designed to minimize deformation between the left and right sensors 3150L, ​​3150R and act as a stable platform from which to detect misalignment between the left and right eyepieces 110L, 110R. Thus, in some embodiments, the body 3110 of the optical sensor assembly 122" may be fabricated from a relatively rigid and / or high strength material, such as metal (e.g., aluminum), ceramic, glass, carbon fiber, or composites thereof. Further, the left and right sensors 3150L, ​​3150R may be disposed on and / or within the body 3110 of the optical sensor assembly 122" such that the left sensor 3150L is positioned in the same plane as the right sensor 3150R, and vice versa. That is, the left and right sensors 3150L, ​​3150R may be laterally aligned with one another, and the body 3110 may serve to maintain such alignment. Thus, in some embodiments, one or more surfaces of the body 3110 of the optical sensor assembly 122" may be geometrically planar. In some examples, the left and right distal portions of the body 3110 of the light sensor assembly 122″ may feature a pair of holes or recessed areas configured to receive and / or engage the left and right sensors 3150L, ​​3150R, respectively. In some embodiments, the left and right sensors 3150L, ​​3150R may be affixed onto or within the body 3110 of the light sensor assembly 122″ using one or more layers of adhesive, one or more other mounting hardware components, or a combination thereof. In this manner, the left and right sensors 3150L, ​​3150R and the body 3110 may be monolithically integrated together. As depicted in FIGS. 31A and 31B , in some examples, the shape of the body 3110 may correspond to that of a right angle prism. However, it should be understood that the body 3110 of the light sensor assembly 122″ may take on any of a variety of different elongated geometries.

[0258] In some embodiments, the body 3110 of the light sensor assembly 122″ may further include one or more features configured to enable or otherwise facilitate mounting or attachment of the light sensor assembly 122″ to the frame 300, such as brackets, through holes, standoffs, threaded sockets, and the like. In some examples, one or more separate mounting hardware components may be utilized to enable or otherwise facilitate mounting or attachment of the light sensor assembly 122″ to the frame 300, such as brackets, standoffs, spacers, adhesive layers, nuts, bolts, and the like. In some embodiments, circuitry components associated with one or both of the left and right sensors 3150L, ​​3150R may be disposed on and / or within the body 3110 of the light sensor assembly 122″. In some embodiments, one or more optical components (e.g., prisms, beam splitters, mirrors, lenses, freeform optical elements, etc.) may be disposed on and / or within one or more of the left and right sensors 3150L, ​​3150R and the body 3110 to redirect light toward the left and right sensors 3150L, ​​3150R or otherwise condition the light for capture by the left and right sensors 3150L, ​​3150R.

[0259] In some embodiments, the light-sensing assembly 122″ may be mounted to a portion of a housing structure of a display subsystem of the virtual image generation system 100. For example, FIGS. 32A and 32B depict perspective views of a front housing structure 3210 associated with a display subsystem for use in the image generation system of FIG. 5. In some examples, the light-sensing assembly 122″ may be mounted to or otherwise attached to an inwardly facing side of a central portion 3212 of the front housing structure 3210. In other examples, the light-sensing assembly 122″ may be mounted to or otherwise attached to an outwardly facing side of a central portion 3222 of the rear housing structure 3220 as shown in FIG. 32B. In either case, the light-sensing assembly 122″ may be encapsulated between the front and rear housing structures 3210, 3220. In some embodiments, one or both portions of the front and rear housing structures 3210, 3220 may be made from plastic, metal, carbon fiber, or a composite thereof. Additional examples of housing structures that may be employed in one or more of the systems described herein are provided in U.S. patent application Ser. No. 16 / 225,961, the entirety of which is incorporated herein by reference.

[0260] In some embodiments, one or more additional components of the display subsystem of the virtual image generation system 100 may be positioned or stored, at least in part, between the front and rear housing structures 3210, 3220. Such one or more components may include, for example, the left and right projection subsystems 108L, 108R, the left and right eyepieces 110L, 110R, and any of a variety of other electronic and / or optical components. In some examples, one or more components that are functional equivalents of, or similar to, the frame 300 as described above may also be positioned or stored, at least in part, between the front and rear housing structures 3210, 3220. In at least some of these examples, the left and right eyepieces 110L, 110R may be carried by such one or more components. In some embodiments, the left and right eyepieces 110L, 110R may be arranged between the front and rear housing structures 3210, 3220 such that the DOEs 174 or 174a-b of the left and right eyepieces 110L, 110R may be exposed to a wearer of the display subsystem, while the DOEs 190 of the left and right eyepieces 110L, 110R are positioned between or adjacent to portions 3212 and 3222 of the front and rear housing structures 3210, 3220. Thus, in these embodiments, the DOEs 190 of the left and right eyepieces 110L, 110R may be hidden by the front and rear housing structures 3210, 3220 and thus outside the FOV of the wearer of the display subsystem. Similarly, for embodiments in which the eyepieces of FIG. 14E are utilized, the left and right eyepieces 110L, 110R may be arranged between the front and rear housing structures 3210, 3220 such that a first portion of each DOE 174a-b is exposed to a wearer of the display subsystem and a second portion of each DOE 174a-b is positioned outside the wearer's FOV, at a location between or adjacent portions 3212 and 3222 of the front and rear housing structures 3210, 3220.While particular embodiments of the present invention have been illustrated and described, it is not intended to limit the invention to the preferred embodiments, and it will be understood that it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to cover alternatives, modifications, and equivalents which may be included within the spirit and scope of the invention as defined by the claims.

Claims

1. 1. A display system comprising: a pair of projection assemblies configured to emit light, the pair of projection assemblies comprising a first projection assembly and a second projection assembly; A pair of eyepieces, a first eyepiece optically coupled to the first projection assembly; a second eyepiece optically coupled to the second projection assembly; and A pair of eyepieces comprising:

1. A sensing assembly comprising a pair of imaging sensors configured to capture an image, the pair of imaging sensors comprising: a first imaging sensor optically coupled to the first projection assembly through the first eyepiece; a second imaging sensor optically coupled to the second projection assembly through the second eyepiece; and a sensing assembly comprising: one or more processors in communication with the pair of projection assemblies and the pair of imaging sensors, the one or more processors comprising: receiving data representative of an image captured by the second imaging sensor; controlling operation of the first projection assembly based at least in part on data received from the second imaging sensor; and one or more processors configured to Equipped with The one or more processors further comprise: receiving data representative of an image captured by the first imaging sensor; controlling operation of the second projection assembly based at least in part on data received from the first imaging sensor; A display system configured to:

2. to control operation of the first projection assembly based at least in part on data received from the second imaging sensor, the one or more processors: Controlling operation of the first projection assembly based at least in part on data received from the first imaging sensor and the second imaging sensor. The display system of claim 1 configured as follows:

3. to control operation of the second projection assembly based at least in part on data received from the first imaging sensor, the one or more processors: Controlling operation of the second projection assembly based at least in part on data received from the first imaging sensor and the second imaging sensor. The display system of claim 1 configured as follows:

4. The sensing assembly further comprises: The display system of claim 1 , comprising an elongated body physically coupled to the pair of imaging sensors.

5. 5. The display system of claim 4, wherein the first imaging sensor is physically coupled to a first distal portion of the elongated body and the second imaging sensor is physically coupled to a second distal portion of the elongated body.

6. The display system of claim 4 , wherein the first imaging sensor is physically coupled to the elongated body in lateral alignment with the second imaging sensor.

7. The display system of claim 1 , further comprising a housing structure, the sensing assembly being mounted to an interior surface of the housing structure.

8. The one or more processors further comprise: generating an image of the virtual scene from a viewpoint of a first rendering camera; causing the first projection assembly to emit light representative of an image of a virtual scene as generated from a perspective of the first rendering camera; generating an image of the virtual scene from a viewpoint of a second rendering camera; causing the second projection assembly to emit light representative of an image of the virtual scene as generated from a viewpoint of the second rendering camera; The display system of claim 1 configured to:

9. to control operation of the first projection assembly based at least in part on data received from the second imaging sensor, the one or more processors: Controlling one or more extrinsic parameters of the first rendering camera based, at least in part, on data received from the second imaging sensor. The display system of claim 8 , configured so that 10. To control operation of the second projection assembly based, at least in part, on data received from the first imaging sensor, the one or more processors: Controlling one or more extrinsic parameters of the second rendering camera based, at least in part, on data received from the first imaging sensor. The display system of claim 8 , configured so that

Images