Folded beam low-angle beam scanner

Abstract

A beam scanner (100) includes: a substrate (102); a tiltable reflector (104) hingedly supported by the substrate (102); and a reflective polarizer (106). The reflective polarizer (106) is supported above the tiltable reflector (104) and is configured to receive a light beam (110) and redirect it to the tiltable reflector (104) to scan the light beam. A projector (120) includes the beam scanner (100) and a light source (112) that provides the light beam (110). The light beam (110) can be modulated in brightness, color, or polarization synchronously with the tilt of the reflector to form an image in an angular domain after propagating through a pupil replicating waveguide (114). At least one folding mirror (206) can be provided for guiding the light beam (110) from the light source (112) around the pupil replicating waveguide (114), resulting in a compact overall configuration.

Description

Technical Field

[0001] The present disclosure relates to optical scanning devices, and more particularly to compact optical scanning devices that can be used in scanning projectors and scanning projector displays. Background Art

[0002] Head-mounted displays (HMDs), helmet-mounted displays, near-eye displays (NEDs), and the like are increasingly being used to display virtual reality (VR) content, augmented reality (AR) content, mixed reality (MR) content, and the like. Such displays are finding applications in a variety of fields, including entertainment, education, training, and biomedical sciences, to name a few. The VR / AR / MR content displayed can be three-dimensional (3D) to enhance the experience and match virtual objects with real objects observed by the user. The user's eye position and gaze direction and / or orientation can be tracked in real time, and the displayed image can be dynamically adjusted based on the user's head orientation and gaze direction to provide an immersive experience into a simulated or augmented environment.

[0003] For head mounted displays, compact display devices are needed. Because the display of an HMD or NED is typically worn on the user's head, a large, bulky, unbalanced and / or heavy display device would be cumbersome and may be uncomfortable for the user.

[0004] Projector-based displays provide images in an angular domain that can be viewed directly by the user's eyes without an intermediate screen or display panel. Imaging waveguides can be used to expand image light carrying the image in an angular domain over the eye box of the display. The lack of a screen or display panel in a scanning projector display can reduce the size and weight of the display. Projector-based displays can use a scanning projector that obtains an image in an angular domain by scanning an image beam with controllable brightness and / or color. It is desirable to make scanning projectors and optical scanners more compact. Summary of the invention

[0005] According to a first aspect of the present invention, there is provided a beam scanner comprising: a substrate; a tiltable reflector hingedly supported by the substrate; and a reflective polarizer, the reflective polarizer being supported above the tiltable reflector and configured to receive a light beam and redirect the light beam to the tiltable reflector to scan the light beam.

[0006] The beam scanner may further include a quarter wave plate (QWP) in the optical path between the reflective polarizer and the tiltable reflector, wherein the QWP is configured to change the polarization state of the optical beam to an orthogonal polarization state upon double-pass propagation of the optical beam through the QWP. The QWP may be supported by the reflective polarizer.

[0007] The beam scanner may also include a folding mirror configured to receive the beam and redirect the beam to the reflective polarizer.

[0008] The folding mirror may be supported by a substrate.

[0009] The beam scanner may further include a housing surrounding the tiltable reflector, wherein the housing supports the reflective polarizer.

[0010] The beam scanner may also include a folding mirror supported by the substrate and optically coupled to the reflective polarizer.

[0011] The housing may include an optical window for receiving and transmitting the light beam therethrough to impinge upon the folding mirror.

[0012] According to a second aspect of the present invention, there is provided a projector comprising: a light source for providing a light beam having a characteristic including at least one of brightness or color; and a beam scanner according to the first aspect.

[0013] The beam scanner may include a folding mirror, and the folding mirror may be a first folding mirror, and the projector may further include a second folding mirror configured to receive the light beam and redirect the light beam to the first folding mirror.

[0014] The beam scanner may further include a housing surrounding the tiltable reflector, wherein the housing supports the reflective polarizer. The housing may include an optical window for receiving the light beam and transmitting the light beam therethrough to impinge on the first folding mirror.

[0015] The projector may also include a controller operably coupled to the light source and the beam scanner for varying characteristics of the light beam in coordination with scanning of the light beam by the beam scanner.

[0016] According to a third aspect of the invention, there is provided a display comprising: a light source for providing a light beam having a characteristic including at least one of brightness or color; a beam scanner of the first aspect; and a pupil replica waveguide configured to receive the light beam reflected from the tiltable reflector and spread the light beam over an eye box of the display.

[0017] The pupil replica waveguide may be substantially parallel to the substrate of the beam scanner.

[0018] The display may also include a first folding mirror configured to receive the light beam and redirect it toward the reflective polarizer.

[0019] The display may also include a second folding mirror configured to receive the light beam and redirect the light beam toward the first folding mirror and around the pupil replica waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Exemplary embodiments will now be described with reference to the accompanying drawings, in which:

[0021] Figure 1 is a side cross-sectional view of a beam scanner including a reflective polarizer;

[0022] Figure 2 is a side cross-sectional view of a beam scanner including a reflective polarizer and a beam folding mirror;

[0023] Figure 3A is a side cross-sectional view of a beam scanner including a reflective polarizer and a pair of beam folding mirrors for routing a beam around an image replicating waveguide;

[0024] Figure 3B is a side cross-sectional view of a non-zero tilt beam scanner including a beam folding mirror;

[0025] Figure 4A and Figure 4B They are Figure 3A and Figure 3B Field of view (FOV) diagram of the beam scanner;

[0026] Figure 5 is a plan view of a 2D scanning micro-electromechanical system (MEMS) mirror;

[0027] Fig. 6A is a schematic diagram of a micro-electromechanical system (MEMS) scanning projector display;

[0028] Figure 6B is a schematic top view of a scanning projector display having an array light source, showing the relationship between the fields of view provided by the individual emitters of the array light source;

[0029] Figure 7 yes Figure 3A 3D view of the package beam scanner;

[0030] Figure 8 is a schematic top view of a near-eye display using a beam scanner of the present disclosure;

[0031] Fig. 9A is an isometric view of a head mounted display of the present disclosure; and

[0032] Fig. 9B Yes Fig. 9A Block diagram of a virtual reality system for a head-mounted device. DETAILED DESCRIPTION

[0033] Although the present invention has been described in conjunction with various embodiments and examples, the present invention is not intended to be limited to these embodiments. On the contrary, the present invention includes various alternatives and equivalents, as understood by those skilled in the art. All statements of the principles, aspects and embodiments of the present disclosure and their specific examples are described here to cover their structural and functional equivalents. In addition, these equivalents are intended to include currently known equivalents and equivalents developed in the future, i.e. any element that performs the same function developed, regardless of structure.

[0034] As used herein, the terms "first", "second", etc. are not intended to imply a sequential order, but are intended to distinguish one element from another, unless explicitly stated. Similarly, the sequential order of method steps does not imply a sequential order of their execution, unless explicitly stated. Figure 1 , Figure 2 and Figure 3A In the drawings, like reference numerals denote like elements.

[0035] A tiltable reflector can be used to scan a light beam emitted by a light source to form an image in an angular domain for direct viewing by a user of the display. As the light beam is scanned, the brightness and / or color of the scanned light beam can vary in coordination with the scan. The brightness and / or color of the light beam is set to correspond to the brightness and / or color of the image pixel currently highlighted or "colored" by the light beam. When the light beam is scanned in two dimensions (e.g., in X and Y viewing angles) across the user's entire field of view (FOV), an entire image is formed. When the frame rate is high enough, the eye integrates the scanned light beam so that the user can see the displayed image with substantially no flicker.

[0036] One problem associated with beam scanners is the reduction in field of view (FOV) caused by the oblique angle of incidence of the beam on the tiltable reflector of the beam scanner. The oblique angle of incidence may be required by the optical geometry used, for example to physically separate the incident beam from the scanned reflected beam. The reduction in FOV is caused by the distortion of the solid angle representing the scanning range of the oblique angle of incidence of the beam at the tiltable reflector.

[0037] According to the present disclosure, the output (scanning) beam can be spatially separated from the input beam by polarization. This eliminates the need to geometrically separate the beams by tilting the angle of incidence, resulting in a compact configuration that provides a nearly straight angle of incidence at the tiltable reflector when the tiltable reflector is in a center (non-tilted) angular position. The low tilt angle of the incident beam enables more efficient use of the scanning range.

[0038] According to the present disclosure, a beam scanner is provided, comprising a substrate, a tiltable reflector hingedly supported by the substrate, and a reflective polarizer supported on the tiltable reflector, the reflective polarizer being configured to receive a beam and redirect the beam to the tiltable reflector to scan the beam. A quarter-wave plate (QWP) may be disposed in the optical path between the reflective polarizer and the tiltable reflector. The QWP may be configured to change the polarization state of the beam to an orthogonal polarization state when the beam propagates through a double pass of the QWP. The QWP may be supported by the reflective polarizer.

[0039] In some embodiments, the beam scanner may further include a folding mirror configured to receive the light beam and redirect the light beam to the reflective polarizer. The folding mirror may be supported by a substrate. A housing may be provided to surround the tiltable reflector. The housing may support the reflective polarizer. In embodiments where the folding mirror is supported by a substrate and optically coupled to the reflective polarizer, the housing may include an optical window for receiving and transmitting the light beam through the optical window to impinge on the folding mirror.

[0040] According to the present disclosure, a projector including a light source and a beam scanner is provided. The light source may be configured to provide a light beam having a characteristic including at least one of brightness or color. The beam scanner may include a substrate, a tiltable reflector hingedly supported by the substrate, and a reflective polarizer supported on the tiltable reflector, the reflective polarizer being configured to receive the light beam and redirect the light beam to the tiltable reflector to scan the light beam.

[0041] In some embodiments, the projector may further include a QWP in the optical path between the reflective polarizer and the tiltable reflector. The QWP may be configured to change the polarization state of the light beam to an orthogonal polarization state as the light beam propagates through the QWP in a double-pass manner. The first folding reflector may be configured to receive the light beam and redirect it to the reflective polarizer. The first folding reflector may be supported by a substrate. The second folding reflector may be configured to receive the light beam and redirect it to the first folding reflector. A housing may be provided surrounding the tiltable reflector. The housing may support the reflective polarizer and may include an optical window for receiving the light beam and transmitting it through to impinge on the first folding reflector. The controller may be operably coupled to the light source and the beam scanner for changing the characteristics of the light beam in coordination with the beam scanner scanning the light beam.

[0042] According to the present disclosure, a display is also provided, the display comprising a light source for providing a light beam, the above-mentioned light beam scanner, and a pupil replication waveguide, the pupil replication waveguide being configured to receive the light beam reflected from the tiltable reflector and spread the light beam over the eye box of the display. The pupil replication waveguide may be arranged substantially parallel to the substrate of the light beam scanner. The first folding mirror may be configured to receive the light beam and redirect it to a reflective polarizer. The second folding mirror may be configured to receive the light beam and redirect the light beam toward the first folding mirror and around the pupil replication waveguide.

[0043] Several embodiments of the beam scanner of the present disclosure will now be considered. Figure 1 , the beam scanner 100 includes a substrate 102 (e.g., a semiconductor substrate) and a tiltable reflector 104 (e.g., a tiltable mirror and / or a grating) hingedly supported by the substrate 102. A reflective polarizer 106 is supported on the tiltable reflector 104 and optically coupled to the tiltable reflector 104. The reflective polarizer 106 can be configured to reflect a light beam 110 of a specific predetermined polarization state toward the tiltable reflector 104 and transmit light of an orthogonal polarization state. The light beam 110 incident on the tiltable reflector 104 can then be scanned around one or two axes. A quarter wavelength wave plate (QWP) 108 can be disposed in the optical path between the reflective polarizer 106 and the tiltable reflector 104. The QWP 108 can be configured to change the polarization state of the light beam 110 to an orthogonal polarization state when the light beam 110 propagates through the QWP 108 in a double-pass manner. For example, the QWP 108 can be oriented with its optical axis at 45 degrees relative to the polarization direction of the linearly polarized light beam 110, so that in a double-pass propagation, the QWP 108 acts as a half-wave plate that rotates the linear polarization of the light beam 110 to an orthogonally oriented linear polarization. As shown, the QWP 108 can be presented separately, or can be supported by the reflective polarizer 106 - the latter configuration tends to be more compact.

[0044] The projector 120 includes a beam scanner 100 and a light source 112 optically coupled to the beam scanner 100. In operation, the light source 112 emits a light beam 110 having controllable characteristics such as brightness, color, etc. The light beam 110 may be circularly polarized. The light beam 110 emitted by the light source 112 impinges on the QWP 108. The QWP 108 is configured and oriented to convert a circular polarization state into a linear polarization state reflected by the reflective polarizer 106. The reflected linearly polarized light beam 110 propagates through the QWP 108 again and becomes circularly polarized. The circularly polarized light beam 110 is reflected back to the QWP 108 by the tiltable reflector 104. This reflection reverses the handedness of the circular polarization. During the third propagation of the light beam 110 through the QWP 108, the light beam 110 becomes linearly polarized in the direction of the polarization vector, which ensures that the light beam 110 is transmitted through the reflective polarizer 106. The transmitted light beam 110 propagates toward the pupil replication waveguide 114. The replica waveguide 114 may include a single waveguide element or a stack of waveguide elements. The pupil replica waveguide 114 expands the light beam 110 onto an eye box 118 of the near-eye display 140, thereby delivering an image in an angular domain to the eye box 118. The substantially parallel placement of the substrate 102 and the pupil replica waveguide 114 may allow the size of the near-eye display 140 to be further reduced.

[0045] Controller 116 is operably coupled to light source 112 and beam scanner 100 and is configured to vary brightness and / or color of beam 110 in coordination with scanning of beam 110 by beam scanner 100. Pupil replicating waveguide 114, light source 112 and beam scanner 100 together form near eye display 140.

[0046] Go to Figure 2 , the projector 220 includes a beam scanner 200. The projector 220 and the beam scanner 200 are similar to Figure 1 The projector 120 and the beam scanner 100 are shown. Figure 2 The beam scanner 200 also includes a first folding mirror 206 in the optical path of the light beam 110 between the light source 112 and the tiltable reflector 104. The first folding mirror 206 can be supported by the substrate 102, can extend from the substrate 102, or can be mounted separately. The first folding mirror 206 can be, for example, a mirror prism or a thin mirror substrate. One advantage of using the first folding mirror 206 is that since the reflective polarizer 106 is relatively Figure 1The smaller angle arrangement in the beam scanner 100 of the embodiment of the present invention further reduces the size of the beam scanner 200. Another advantage of the beam scanner 200 is that the light source 112 can be arranged on the opposite side of the pupil replication waveguide 114, providing size savings for the near-eye display 240. The substantially parallel placement of the substrate 102 and the pupil replication waveguide 114 can allow for further reduction in the size of the near-eye display 240. In this document and throughout the rest of the present disclosure, the term "substantially parallel" is considered to mean exactly parallel within 10-15 degrees.

[0047] Reference Figure 3A , beam scanner 300A is similar to Figure 2 The projector 320A includes a light source 112, which is optically coupled to the beam scanner 300A through a second folding mirror 306 in the optical path of the light beam 110 between the light source 112 and the tiltable reflector 104. One advantage of using two folding mirrors, namely the first folding mirror 206 and the second folding mirror 306, is that the size of the beam scanner 300A can be further reduced. The two folding mirrors 206 and 306 enable the light beam 110 to be redirected around the pupil replica waveguide 114.

[0048] The beam scanner 300A may also include an optical window 344. Together with the reflective polarizer 106, the optical window 344 may provide a housing for the tiltable reflector 104 and the first folding mirror 206, so that the tiltable reflector 104 can be sealed and packaged, if desired. In the projector 320A, when the tiltable reflector 104 is not tilted, the light beam 110 impinges on the tiltable reflector 104 at a zero angle of incidence or at a small non-zero angle.

[0049] The near-eye display 340A includes a pupil replicating waveguide 114 and a projector 320A optically coupled to the pupil replicating waveguide 114. In operation, the tiltable reflector 104 is scanned about one or two tilt axes. Figure 3A In the embodiment, the tiltable reflector 104 is arranged around a vertical Figure 3A The axis of the plane of the scanning beam 110. The fanning of three scanning beams 110A, 110B and 110C is shown to illustrate the scanning.

[0050] Figure 3B A beam scanner 300B is depicted that does not include an internal folding mirror or reflective polarizer. Figure 3A The beam scanner 300A is comparatively considered to the beam scanner 300B to illustrate the effect of the tilt angle of the light beam 110 incident on the tiltable reflector 104 compared to the normal incidence angle when the tiltable reflector 104 is in a nominal orientation, i.e., parallel to the substrate 102. Figure 3BThe beam scanner 300B includes a tiltable reflector 104 hingedly supported on a substrate 102 and protected by a window 346. An external folding mirror 348 redirects the light beam 110 emitted by the light source 112 to impinge on the tiltable reflector 104 through the window 346 at an oblique angle of incidence.

[0051] The projector 320B includes a light source 112, which is optically coupled to the beam scanner 300B through an external folding mirror 348 disposed in the optical path of the light beam 110 between the light source 112 and the tiltable reflector 104. The near-eye display 340B includes the tiltable reflector 104 and a pupil replicating waveguide 350. The tiltable reflector 104 reflects the light beam 110 to be incident on the pupil replicating waveguide 350 at different incident angles. In the projector 320B, the light beam 110 impinges on the tiltable reflector 104 at an oblique incident angle, i.e., away from a normal incident angle.

[0052] Figure 4A and Figure 4B The vertical incidence angle ( Figure 4A ) compared with oblique incident angle ( Figure 4B ) onto the tiltable reflector 104. Figure 4A 4 and 402A (shaded rectangle). The zero-tilt scan angle region 400A and the associated inscribed rectangular FOV 402A (shaded rectangle) are shown in units of tanx and tany, the tangents of the corresponding ray angles ?x and ?y, respectively. The zero-tilt FOV 402A solid angle covers most of the angle region 400A. By comparison, Figure 4B Oblique incidence scan angular region 400B and associated inscribed rectangular FOV 402B (shaded rectangle) are shown. FOV 402B solid angle occupies a smaller percentage of angular region 400B and has a different aspect ratio. For example, to ensure Figure 3A To ensure the FOV of the near-eye display 340A, the tiltable reflector 104 needs to be tilted within a specific tilt range about the X-axis and about the Y-axis. Figure 3B To achieve the same FOV of the near-eye display 340B at a non-zero tilt position, the tiltable reflector 104 needs to have a larger tilt range about the X-axis and the Y-axis. Therefore, the zero-tilt or low-tilt coupling of the light beam 110 to the tiltable reflector 104 improves the utilization of the scanning range of the tiltable reflector 104, making the scanning range of the tiltable reflector 104 smaller and / or the field of view at the same scanning range of the tiltable reflector 104 wider. It should be noted that the configurations and advantages disclosed herein can be applied to various types of projector-based displays, not necessarily near-eye displays.

[0053] In some embodiments, the beam scanner of the projector described herein may include a micro-electromechanical system (MEMS) scanner. Figure 5, a two-dimensional (2D) micro-electromechanical system (MEMS) scanner 500 includes a reflector 510, such as a mirror or a diffraction grating, which is supported by a pair of first torsion hinges 501, thereby allowing the reflector 510 to be tilted about the X-axis. The first torsion hinge 501 extends from the reflector 510 to a gimbal 520, and the gimbal 520 is supported by a pair of second torsion hinges 502, and the second torsion hinge 502 extends from the gimbal 520 to a fixed base 522 for tilting the gimbal 520 and the reflector 510 about the Y-axis. Actuators 551, 552 can be disposed below the reflector 510 and / or the gimbal 520 to provide a force for actuating the reflector 510 to tilt about the X and Y axes. The actuators 551, 552 can be electrostatic, electromagnetic, piezoelectric, etc. For electrostatic mirror actuation, a comb drive can be located on the torsion hinge member. For example, in Figure 5 In the illustrated embodiment, a first actuator 551 may be disposed under an edge of the reflector 510 to tilt the reflector 510 about the X-axis. A second actuator 552 may be disposed under the gimbal 520 to tilt the gimbal 520 and the reflector 510 about the Y-axis. Note that the reflector 510 may be offset from the center of the corresponding substrate if desired.

[0054] A feedback circuit 554 may be provided to determine the X and Y tilt angles of the reflector 510. The feedback circuit 554 may measure the capacitance between the first electrostatic actuator 551 and the reflector 510 to determine the X tilt, and measure the capacitance between the second electrostatic actuator 552 and the gimbal 520 to determine the Y tilt. Separate electrodes may also be provided specifically for the feedback circuit 554. In some embodiments, the feedback circuit 554 may provide a synchronization or trigger pulse when the reflector 510 is tilted at a specific X and / or Y angle including a zero angle. Figure 5 The reflector 510 corresponds to Figure 1 , Figure 2 , Figure 3A and Figure 3B A tiltable reflector 104 is provided.

[0055] Go to Fig. 6A , the scanning projector display 600 includes a light source assembly 602 for providing a divergent light beam 604D. An optional collimator 650 is optically coupled to the light source assembly 602 to collimate the divergent light beam 604D and provide a collimated light beam 604. Figure 5 The scanner of the 2D MEMS scanner 500 is optically coupled to the collimator 650. The controller 612 may be operably coupled to the electronic driver 606, which is coupled to the light source assembly 602. The controller 612 is also coupled to the 2D MEMS scanner 500 for tilting the reflector 510 of the 2D MEMS scanner 500.

[0056] A collimator 650 (e.g., a lens, a reflector, etc.) is optically coupled to the pulse light source 602 for collimating the divergent light beam 604D to obtain the collimated light beam 604. Any optical component having optical power (i.e., focusing or collimating capability) may be used in the collimator 650, such as a concave mirror, a diffractive lens, a folded beam free-form optical element, etc. The reflector 510 of the 2D MEMS scanner 500 is optically coupled to the collimator 650 for receiving and angularly scanning the collimated light beam 604.

[0057] The electronic driver 606 is configured to provide power supply electrical pulses to actuate the light source assembly 602. The controller 612 sends commands to the electronic driver 606 to actuate the light source assembly 602 in coordination with the tilted 2D MEMS scanner 500 for "drawing" or rasterizing an image in the angular domain. When viewed by a human eye, the image in the angular domain is projected by the cornea and lens of the eye to become a spatial domain image on the retina of the eye.

[0058] In some embodiments, the scanner of the projector display may include a 1D tiltable mirror, and the light source assembly 602 may include a linear array of light sources to provide multiple image pixels in a direction perpendicular to the scanning direction. The linear array of light sources may also be used in a 2D scanner. In some embodiments, the 2D MEMS scanner 500 may be replaced with a pair of 1D tiltable mirrors, i.e., one for scanning about the X axis and the other for scanning about the Y axis. The two 1D tiltable mirrors may be coupled, for example, via pupil relay optics. Other types of scanners may be used, such as diffraction or acousto-optic scanners.

[0059] The light source assembly 602 may include one or more single-mode or multi-mode light sources, such as a side-emitting laser diode, a vertical cavity surface-emitting laser diode, a superluminescent light-emitting diode (SLED), or a light-emitting diode. The pulse energy of the light pulses may be selected to be below a threshold energy, which is equal to the pixel time interval multiplied by a threshold optical power of the light source. For an SLED light source, the threshold optical power of the SLED may be a laser threshold optical power of the SLED.

[0060] Figure 6BThe operation of the scanning projector display 600 is further illustrated. In this example, the light source assembly 602 is a multi-emitter assembly that includes three emitters that provide three light beams (only the principal ray is shown) 621 (dotted lines), 622 (solid lines), and 623 (dashed lines). A collimator 650 collimates the light beams 621, 622, and 623. By selecting appropriate geometry, such as the distance and focal length of the collimator 650, the latter can also cause the light beams 621, 622, and 623 to be incident on the center of the reflector 510 at slightly different angles of incidence, for scanning all three light beams 621, 622, and 623 together. Due to the different angles at which the light beams 621, 622, and 623 are incident on the tiltable reflector 510, the respective scanning areas 631 (dotted lines), 632 (solid lines), and 633 (dashed lines) of the light beams 621, 622, and 623, respectively, are offset from each other as shown. Controller 612 can account for these spatial offsets by providing corresponding delays to the drive signals for the three emitters of multi-emitter light source assembly 602. A combination of spatial offsets and delays in energizing the individual emitters can be provided so as to effectively triple the spatial resolution of scanning projector display 600 in common scan area 630 compared to the case of a single emitter.

[0061] Reference now Figure 7 , the packaged MEMS scanner 700 has Figure 3A The packaged MEMS scanner 700 ( Figure 7 ) includes a sealed package or housing 702 formed by the reflective polarizer 106, the optical window 344 and the sidewalls 704. The housing 702 encloses the tiltable reflector 104 and the first folding mirror 206. The housing 702 can be vacuum sealed or filled with an inert gas, such as argon, to provide a stable environment for the tiltable reflector 104.

[0062] Go to Figure 8 , a near eye display (NED) 800 includes a frame 801 having the form factor of a pair of glasses. The frame 801 can support for each eye: a projector 802 for providing display light carrying an image in an angular domain; an electronic driver 804 operably coupled to the projector 802 for powering the projector 802; and a pupil replicator 832 (e.g., a pupil replicating waveguide assembly) optically coupled to the projector 802.

[0063] Each projector 802 may include a beam scanner as described herein, such as but not limited to Figure 1 The beam scanner 80, Figure 2 The beam scanner 200, Figure 3A The beam scanner 300A, Figure 3B The beam scanner 300B, Figure 7 The beam scanner 700 of the embodiment of the present invention can include a tiltable reflector of a MEMS beam scanner, for example. In some embodiments, each projector 802 includes Figure 1 Projector 120, Figure 2 Projector 220, Figure 3A Projector 320A, Figure 3B Projector 320B, etc. The light source for these projectors may include a substrate supporting an array of single-emitter or multi-emitter semiconductor light sources (e.g., side-emitting laser diodes, vertical cavity surface-emitting laser diodes, SLEDs, or light-emitting diodes) for providing multiple light beams. The collimator of the light source may include a concave mirror, a volume lens, a Fresnel lens, a holographic lens, a free-form prism, etc. The pupil replicator 832 may include a waveguide equipped with multiple surface reliefs and / or volume holographic gratings. The function of the pupil replicator 832 is to provide multiple laterally offset copies of the display beam provided by the projector 802 at each eye box 812.

[0064] The controller 805 is operably coupled to the light source and the tiltable reflector of the projector 802. The controller 805 can be configured to determine the X and Y tilt angles of the tiltable reflector of the projector 802. The controller 805 determines which pixel or pixels of the image to be displayed correspond to the determined X and Y tilt angles. The controller 805 then determines the brightness and / or color of these pixels and operates the electronic driver 804 accordingly to provide power supply electrical pulses to the light source of the projector 802 to generate light pulses of power levels corresponding to the determined pixel brightness and color.

[0065] In some embodiments, the controller 805 can be configured to operate a tiltable reflector for each eye so that the light beam reflected from the tiltable reflector has a beam angle corresponding to a pixel of the image to be displayed. The controller 805 can be further configured to operate the light source in coordination with the operation of the tiltable reflector so that the light beam has a brightness and / or color corresponding to the first pixel to be displayed. In a multi-light source / multi-emitter embodiment, the controller 805 can be configured to operate the corresponding light sources / emitters in coordination to provide a larger FOV, improved scanning resolution, increased display brightness, etc., as described herein. For example, in an embodiment where the projector for two user eyes includes two light sources, the controller can be configured to operate each of the two tiltable reflectors so that the second light beam reflected from the tiltable reflector has a beam angle corresponding to a second pixel of the image to be displayed, and operate the second light source in coordination with the operation of the tiltable reflector so that the second light beam has a brightness corresponding to the second pixel.

[0066] Embodiments of the present disclosure may include an artificial reality system or be implemented in conjunction with an artificial reality system. The artificial reality system adjusts sensory information about the external world obtained through senses such as visual information, audio, touch (somatosensory) information, acceleration, balance, etc. in some way before presenting it to the user. As a non-limiting example, artificial reality may include virtual reality (VR), augmented reality (AR), mixed reality (MR), mixed reality, or some combination and / or derivative thereof. Artificial reality content may include fully generated content or generated content combined with captured (e.g., real world) content. Artificial reality content may include video, audio, somatic or tactile feedback, or some combination thereof. Any of the content may be presented in a single channel or multiple channels, such as in a stereoscopic video that produces a three-dimensional effect on the viewer. In addition, in some embodiments, artificial reality may also be associated with an application, product, accessory, service, or some combination thereof, which is used, for example, to create content in artificial reality and / or otherwise used in artificial reality (e.g., performing activities in artificial reality). Artificial reality systems that provide artificial reality content can be implemented on a variety of platforms, including wearable displays such as HMDs connected to a host system, standalone HMDs, near-eye displays with eyeglass form factors, mobile devices or computing systems, or any other hardware platform capable of providing artificial reality content to one or more viewers.

[0067] Reference Fig. 9A , HMD 900 is an example of an AR / VR wearable display system that surrounds the user's face for greater immersion in an AR / VR environment. HMD 900 is, for example, Figure 1 Near-eye display 140, Figure 2 Near-eye display 240, Figure 3A Near-eye display 340A, Figure 3B Near-eye display 340B or Fig. 6A and Figure 6B An embodiment of a scanning projector display 600 of the present invention. The function of the HMD 900 is to enhance the view of the physical, real environment with computer-generated images, and / or to generate a completely virtual 3D image. The HMD 900 may include a front body 902 and a strap 904. The front body 902 is configured to be placed in front of the user's eyes in a secure and comfortable manner, and the strap 904 can be stretched to secure the front body 902 on the user's head. A display system 980 can be set in the front body 902 for presenting AR / VR images to the user. The side 906 of the front body 902 can be opaque or transparent.

[0068] In some embodiments, the front body 902 includes a positioner 908 and an inertial measurement unit (IMU) 910 for tracking the acceleration of the HMD 900, and a position sensor 912 for tracking the position of the HMD 900. The IMU 910 is an electronic device that generates data indicating the position of the HMD 900 based on measurement signals received from one or more position sensors 912, and the position sensor 912 generates one or more measurement signals in response to the movement of the HMD 900. Examples of the position sensor 912 include: one or more accelerometers, one or more gyroscopes, one or more magnetometers, another suitable type of sensor that detects movement, a type of sensor used for error correction of the IMU 910, or some combination thereof. The position sensor 912 can be located outside the IMU 910, inside the IMU 910, or some combination thereof.

[0069] The localizer 908 is tracked by an external imaging device of the virtual reality system so that the virtual reality system can track the position and orientation of the entire HMD 900. The information generated by the IMU 910 and the position sensor 912 can be compared with the position and orientation obtained by tracking the localizer 908 to improve the tracking accuracy of the position and orientation of the HMD 900. When the user moves and rotates in 3D space, accurate position and orientation are important for presenting an appropriate virtual scene to the user.

[0070] The HMD 900 may also include a depth camera assembly (DCA) 911 that captures data describing depth information of a local area surrounding some or all of the HMD 900. To this end, the DCA 911 may include a laser radar (LIDAR) or similar device. The depth information may be compared with information from the IMU 910 to more accurately determine the position and orientation of the HMD 900 in 3D space.

[0071] The HMD 900 may also include an eye tracking system 914 for determining the orientation and position of the user's eyes in real time. The position and orientation of the eyes obtained also allow the HMD 900 to determine the gaze direction of the user and adjust the image generated by the display system 980 accordingly. In one embodiment, the vergence, i.e., the convergence angle of the gaze of the user's eyes, is determined. The determined gaze direction and vergence angle can also be used to compensate for visual artifacts that depend on the viewing angle and eye position in real time. In addition, the determined vergence and gaze angle can be used to interact with the user, highlight objects, bring objects to the foreground, create additional objects or pointers, etc. An audio system may also be provided, which includes, for example, a set of small speakers built into the front fuselage 902.

[0072] refer to Fig. 9B , the AR / VR system 950 includes: Fig. 9AThe HMD 900 includes an external console 990 storing various AR / VR applications, setup and calibration procedures, 3D videos, etc., and an input / output (I / O) interface 915 for operating the console 990 and / or interacting with the AR / VR environment. The HMD 900 can be "tethered" to the console 990 with a physical cable, or via a Bluetooth connection such as a Bluetooth A wireless communication link such as Wi-Fi is connected to the console 990. There may be multiple HMDs 900, each HMD 900 having an associated I / O interface 915, and each HMD 900 and I / O interface 915 communicate with the console 990. In alternative configurations, different and / or additional components may be included in the AR / VR system 950. In addition, in some embodiments, in combination with Fig. 9A and Fig. 9B The functionality described by one or more components shown may be combined with Fig. 9A and Fig. 9B The described manner is distributed among the components in different ways. For example, some or all of the functions of the console 990 may be provided by the HMD 900, and vice versa. The HMD 900 may be equipped with a processing module capable of implementing such functions.

[0073] As above reference Fig. 9A As described above, the HMD 900 may include an eye tracking system 914 (eg, for tracking eye position and orientation, determining gaze angle and convergence angle, etc.) Fig. 9B ); an IMU 910 for determining the position and orientation of the HMD 900 in 3D space; a DCA 911 for capturing the external environment; a position sensor 912 for independently determining the position of the HMD 900; and a display system 980 for displaying AR / VR content to the user. The display system 980 includes ( Fig. 9B) electronic display 925, such as, but not limited to, a liquid crystal display (LCD), an organic light emitting display (OLED), an inorganic light emitting display (ILED), an active matrix organic light emitting diode (AMOLED) display, a transparent organic light emitting diode (TOLED) display, a projector, or a combination thereof. The display system 980 also includes an optical block 930, whose function is to transmit the image generated by the electronic display 925 to the user's eyes. The optical block may include various lenses, such as a refractive lens, a Fresnel lens, a diffractive lens, an active or passive Pancharatnam-Berry phase (PBP) lens, a liquid lens, a liquid crystal lens, etc., a pupil replica waveguide, a grating structure, a coating, etc. The display system 980 may also include a zoom module 935, which may be a part of the optical block 930. The function of the zoom module 935 is to adjust the focus of the optical block 930, such as compensating for vergence-accommodation conflict, correcting for visual defects of a specific user, offsetting aberrations of the optical block 930, etc.

[0074] The I / O interface 915 is a device that allows a user to send an action request and receive a response from the console 990. An action request is a request to perform a specific action. For example, an action request may be an instruction to start or end the capture of image or video data or an instruction to perform a specific action within an application. The I / O interface 915 may include one or more input devices, such as a keyboard, a mouse, a game controller, or any other suitable device for receiving an action request and transmitting the action request to the console 990. The action request received by the I / O interface 915 is transmitted to the console 990, and the console 990 performs an action corresponding to the action request. In some embodiments, the I / O interface 915 includes an IMU that captures calibration data indicating an estimated position of the I / O interface 915 relative to the initial position of the I / O interface 915. In some embodiments, the I / O interface 915 may provide tactile feedback to the user according to instructions received from the console 990. For example, tactile feedback may be provided when an action request is received, or the console 990 transmits instructions to the I / O interface 915 so that the I / O interface 915 generates tactile feedback when the console 990 performs an action.

[0075] The console 990 may provide content to the HMD 900 for processing based on information received from one or more of the following: the IMU 910, the DCA 911, the eye tracking system 914, and the I / O interface 915. Fig. 9B In the example shown, the console 990 includes an application memory 955, a tracking module 960, and a processing module 965. Some embodiments of the console 990 may have a Fig. 9B Similarly, the functions described further below may be combined with Fig. 9A and Fig. 9B The different approaches described are distributed among the components of console 990 .

[0076] The application memory 955 may store one or more applications for execution by the console 990. An application is a set of instructions that, when executed by the processor, generates content for presentation to the user. The content generated by the application may be responsive to input received from the user via movement of the HMD 900 or the I / O interface 915. Examples of applications include: gaming applications, presentation and conferencing applications, video playback applications, or other suitable applications.

[0077] Tracking module 960 may calibrate AR / VR system 950 using one or more calibration parameters, and may adjust one or more calibration parameters to reduce errors in the determination of the position of HMD 900 or I / O interface 915. The calibration performed by tracking module 960 also takes into account information received from IMU 910 in HMD 900 and / or an IMU (if any) included in I / O interface 915. In addition, if tracking of HMD 900 is lost, tracking module 960 may recalibrate some or all of AR / VR system 950.

[0078] The tracking module 960 may track the movement of the HMD 900 or the I / O interface 915, the IMU 910, or some combination thereof. For example, the tracking module 960 may determine the position of a reference point of the HMD 900 in a map of the local area based on information from the HMD 900. The tracking module 960 may also determine the position of the reference point of the HMD 900 or the reference point of the I / O interface 915 using data from the IMU 910 indicating the position of the HMD 900, or using data from an IMU included in the I / O interface 915 indicating the position of the I / O interface 915, respectively. Furthermore, in some embodiments, the tracking module 960 may predict the future position of the HMD 900 using a portion of the data from the IMU 910 indicating the position of the HMD 900 and a representation of the local area from the DCA 911. The tracking module 960 provides the estimated or predicted future position of the HMD 900 or the I / O interface 915 to the processing module 965.

[0079] The processing module 965 may generate a 3D map of an area (“local area”) surrounding some or all of the HMD 900 based on information received from the HMD 900. In some embodiments, the processing module 965 determines depth information for the 3D map of the local area based on information related to a technique for calculating depth received from the DCA 911. In various embodiments, the processing module 965 may use the depth information to update a model of the local area and generate content based in part on the updated model.

[0080] The processing module 965 executes an application within the AR / VR system 950 and receives position information, acceleration information, velocity information, predicted future position, or a combination thereof of the HMD 900 from the tracking module 960. Based on the received information, the processing module 965 determines the content provided to the HMD 900 for presentation to the user. For example, if the received information indicates that the user has looked to the left, the processing module 965 generates content for the HMD 900 that mirrors the user's movement in a virtual environment or in an environment that augments a local area with additional content. In addition, the processing module 965 performs an action within an application executed on the console 990 in response to an action request received from the I / O interface 915, and provides feedback to the user of the execution of the action. The feedback provided may be visual or auditory feedback via the HMD 900 or tactile feedback via the I / O interface 915.

[0081] In some embodiments, based on the eye tracking information (e.g., the orientation of the user's eyes) received from the eye tracking system 914, the processing module 965 determines the resolution of the content provided to the HMD 900 for presentation to the user on the electronic display 925. The processing module 965 may provide the HMD 900 with content that has a maximum pixel resolution in the foveal region of the electronic display 925 where the user is looking. The processing module 965 may provide a lower pixel resolution in other areas of the electronic display 925, thereby reducing the power consumption of the AR / VR system 950 and saving computing resources of the console 990 without compromising the user's visual experience. In some embodiments, the processing module 965 may further use the eye tracking information to adjust the position of an object displayed on the electronic display 925 to prevent vergence accommodation conflicts and / or to counteract optical distortions and aberrations.

[0082] Hardware for implementing the various illustrative logics, logic blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration. Alternatively, some steps or methods may be performed by circuits specific to a given function.

[0083] The present disclosure is not limited to the scope of the specific embodiments described herein. In fact, according to the foregoing description and the accompanying drawings, in addition to the embodiments and modifications described herein, various other embodiments and modifications will be apparent to those of ordinary skill in the art. Therefore, these other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described herein in the context of a specific embodiment in a specific environment for a specific purpose, it will be appreciated by those skilled in the art that its usefulness is not limited thereto, and the present disclosure can be advantageously implemented in any number of environments for any number of purposes. Therefore, the claims set forth below should be interpreted according to the full scope of the present disclosure as described herein.

Claims

1. A display comprising: a light source for providing a light beam having a characteristic, the characteristic comprising at least one of brightness or color; Beam Scanner, including: substrate; a tiltable reflector hingedly supported by the base plate; a reflective polarizer supported above the tiltable reflector and configured to receive the light beam and redirect the light beam toward the tiltable reflector to scan the light beam; a housing surrounding the tiltable reflector; and a first folding mirror supported by the substrate and configured to receive the light beam and redirect the light beam toward the reflective polarizer; and a pupil replicating waveguide configured to receive the light beam reflected from the tiltable reflector and spread the light beam over an eye box of the display; wherein the housing supports the reflective polarizer; wherein the housing comprises an optical window for receiving the light beam and transmitting the light beam therethrough to illuminate the first folding reflector; and Wherein the light source and the beam scanner are arranged on opposite sides of the waveguide.

2. The display of claim 1 wherein the pupil replica waveguide is parallel to the substrate of the beam scanner.

3. A display according to claim 1 or 2, further comprising a second folding mirror configured to receive the light beam and redirect the light beam towards the first folding mirror and around the pupil replica waveguide.

4. A display according to claim 1 or 2, wherein the beam scanner further comprises a quarter wavelength wave plate (QWP) in the optical path between the reflective polarizer and the tiltable reflector, wherein the QWP is configured to change the polarization state of the light beam into an orthogonal polarization state during double-pass propagation of the light beam through the QWP. The display of claim 4 , wherein the QWP is supported by the reflective polarizer.

6. The display of claim 1 or 2, further comprising a controller operably coupled to the light source and the beam scanner for varying the characteristic of the light beam in coordination with scanning of the light beam by the beam scanner.

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