Method and system for fiber optic scanning projector

Abstract

The present invention relates to a method and system for a fiber scanning projector. A fiber scanning projector includes: a piezoelectric element; and a scanning optical fiber mechanically coupled to the piezoelectric element. The fiber scanning projector also includes: an optical component part, which is operable to receive light from the scanning optical fiber. The optical component part includes: a prism element; a collimating element coupled to the prism element at an interface; a quarter wave plate; and a polarization beam splitter disposed at the interface.

Description

[0001] This application is a divisional application of the invention application with application date of March 21, 2018, application number 201880019638.6, and invention name “Method and system for fiber optic scanning projector”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 474,461, filed on March 21, 2017, entitled “Method and System for FiberScanning Projector,” the disclosure of which is incorporated herein by reference in its entirety for all purposes. Background Art

[0004] 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 an observer in such a way that they appear to be real or can be perceived as real. Virtual reality or "VR" scenarios typically involve the presentation of digital or virtual image information that is opaque to other actual real-world visual input; augmented reality or "AR" scenarios typically involve the presentation of digital or virtual image information as an enhancement to the visualization of the actual world around the observer.

[0005] Despite the advances made in these display technologies, there is a need in the art for improved methods and systems relating to augmented reality systems, and particularly display systems. Summary of the invention

[0006] The present invention generally relates to methods and systems related to projection display systems including wearable displays. More particularly, embodiments of the present invention provide methods and systems for volumetric displays (also known as light field displays) that produce volumetric sculptures of light at more than one depth plane. The present invention is applicable to a variety of applications in computer vision and image display systems.

[0007] According to an embodiment of the present invention, a projector is provided. The projector includes: a scanning light source, which defines a convex object surface; and an optical component part, which is operable to receive light from the scanning light source. The optical component part includes: a prism element; a collimating element coupled to the prism element at an interface; a quarter wave plate; and a polarization beam splitter disposed at the interface.

[0008] According to an embodiment of the present invention, a fiber scanning projector is provided. The fiber scanning projector comprises: a piezoelectric element; a scanning optical fiber mechanically coupled to the piezoelectric element; and an optical component part operable to receive light from the scanning optical fiber. The optical component part comprises: a prism element; a collimating element coupled to the prism element at an interface; a quarter wave plate; and a polarization beam splitter disposed at the interface.

[0009] According to another embodiment of the present invention, a fiber scanning projector is provided. The fiber scanning projector includes: a piezoelectric element; and a scanning optical fiber, which passes through and is mechanically coupled to the piezoelectric element. The scanning optical fiber emits light along an optical path. The fiber scanning projector also includes a reflector, which includes a hole. The scanning optical fiber passes through the hole. The fiber scanning projector also includes a collimating reflector arranged along the optical path.

[0010] According to a specific embodiment of the present invention, a fiber scanning projector is provided. The fiber scanning projector includes: a piezoelectric element; and a scanning optical fiber that passes through and is mechanically coupled to the piezoelectric element. The scanning optical fiber emits light along an optical path. The fiber scanning projector also includes: a first polarization-sensitive reflector disposed along the optical path; a quarter-wave plate disposed adjacent to the first polarization-sensitive reflector; and a second polarization-sensitive reflector disposed along the optical path.

[0011] Many benefits over conventional techniques are achieved through the present invention. For example, embodiments of the present invention provide methods and systems that can be used to display images to a user in a form factor comparable to standard glasses. In some embodiments, an image projector integrated with a fiber scanning light source can be adapted within the frame of the glasses. These and other embodiments of the present invention, along with their many advantages and features, are described in more detail in conjunction with the following text and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1A is a simplified perspective view illustrating a fiber scanning projector according to an embodiment of the present invention.

[0013] Figure 1B is a simplified cross-sectional perspective view illustrating a fiber scanning projector according to an embodiment of the present invention.

[0014] Figure 1C Optical paths in a viewing optical assembly (VOA) that may be used to present a digital or virtual image to a viewer according to an embodiment of the present invention are schematically illustrated.

[0015] Figure 1D A partial cross-sectional view of a waveguide scanning system using a silicon-based waveguide in accordance with an embodiment of the present invention is shown.

[0016] Figure 1E is a partial cross-sectional view illustrating the structure of an eyepiece according to an embodiment of the present invention.

[0017] Figure 2A is a ray tracing diagram illustrating the propagation of light through portions of an optical assembly according to an embodiment of the present invention.

[0018] Figure 2B is a side view of an alternative optical assembly portion according to an alternative embodiment of the present invention.

[0019] Figure 2C is a side view of a portion of an optical assembly based on a beamsplitter cube in accordance with an embodiment of the present invention.

[0020] Figure 2D is a side view of another alternative optical assembly portion according to an alternative embodiment of the present invention.

[0021] Figure 2E is a side view of a portion of a multi-polarization tilted reflector optical assembly according to an alternative embodiment of the present invention.

[0022] Figure 2F is a side view of an optical assembly including a Mangin reflector according to an embodiment of the present invention.

[0023] Figure 2G is a side view of an optical assembly including a Mangin reflector according to an alternative embodiment of the present invention.

[0024] Figure 2H is a side view of an optical assembly including a 3D printed lens according to an embodiment of the present invention.

[0025] Figure 3 is a simplified perspective view of an optical component portion of a fiber scanning projector according to an embodiment of the present invention.

[0026] Figure 4 is a simplified perspective view of elements of an optical assembly portion during manufacture in accordance with an embodiment of the present invention.

[0027] Figure 5 is a simplified schematic diagram illustrating a fiber scanning projector 500 according to an alternative embodiment of the present invention.

[0028] Fig. 6A A fiber scanning projector according to an alternative embodiment of the present invention is illustrated.

[0029] Figure 6B is an alternative fiber scanning projector according to an embodiment of the present invention.

[0030] Figure 6Cis another alternative fiber scanning projector according to an embodiment of the present invention.

[0031] Fig.6D It is yet another alternative fiber optic scanning projector according to an embodiment of the present invention.

[0032] Fig. 7A is a schematic diagram illustrating a lensed optical fiber tip according to an embodiment of the present invention.

[0033] Figure 7B is a schematic diagram illustrating a lensed optical fiber tip according to another embodiment of the present invention.

[0034] Figure 7C is a schematic diagram illustrating a lensed optical fiber tip according to an alternative embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention generally relates to methods and systems related to projection display systems including wearable displays. More particularly, embodiments of the present invention provide methods and systems for volumetric displays (also known as light field displays) that produce volumetric sculptures of light at more than one depth plane. The present invention is applicable to a variety of applications in computer vision and image display systems.

[0036] Figure 1A 1 is a simplified perspective view illustrating a fiber scanning projector according to an embodiment of the present invention. The fiber scanning projector 100, which may have a size of about 2 mm x 2 mm x 7 mm, includes a fiber input 110, a fiber oscillation region 120, and an optical component portion 130. Driven by a piezoelectric actuator (not shown), the optical fiber oscillates in the fiber oscillation region 120, for example, in a spiral configuration with an angular deflection that increases during projection of the light for a given frame time. Input light to the fiber scanning projector is provided by the fiber input 110, and output light from the fiber scanning projector is provided by one or more of the surfaces of the optical component portion 130. Various elements of the fiber scanning projector are described more fully throughout this specification.

[0037] Figure 1B FIG. 1 is a simplified cross-sectional perspective view illustrating a fiber scanning projector according to an embodiment of the present invention. Figure 1B , the fiber scanning projector 100 has been rotated horizontally. A fiber input 110 is illustrated on the right hand side of the figure to provide input to a fiber oscillating region 120, which includes a piezoelectric actuator 150 supported by a fixed collar 152 (and driven by an electrical signal from wiring not shown), and a scanning fiber 154 disposed in a mechanical housing 156. As described more fully herein, the optical assembly portion 130 receives light from the scanning fiber 154.

[0038] During operation, a scanning optical fiber 154 mechanically attached to the piezoelectric actuator 150 oscillates in the optical fiber oscillation region 120. In an embodiment, the piezoelectric actuator 150 includes four electrodes distributed at circumferential positions offset by 90° relative to each other. Thus, positive and negative voltages applied to opposite sides of the piezoelectric actuator can cause the actuator and the scanning optical fiber to bend within the plane of the electrodes. By synchronously driving all four electrodes, oscillation of the optical fiber can be achieved. When light leaves the scanning optical fiber 154, it is coupled to the optical component portion 130, as described more fully below.

[0039] As described more fully herein, small form factors comparable to standard glasses are enabled by embodiments of the present invention. By utilizing embodiments of the present invention, displays with desired fields of view, depth of resolution, integrated inertial motion units (IMUs), cameras, audio components, etc. are provided. In some embodiments, Figure 1A and 1B The fiber scanning projector 100 illustrated in the figure is installed in the temple or frame of the glasses and works in combination with the eyepiece set in the frame to guide the projection light toward the user's eyes. The size of the fiber scanning projector 100 enables the integration of multiple fiber scanning projectors that can guide light toward each eye, and the field of view is increased by splicing the display area. As an example, if two projectors are used for each eye, a diagonal field of view of 89° can be provided using two projectors. Using four projectors for each eye, a diagonal field of view of 134° can be achieved. In addition, in addition to the increase in the field of view, additional depth planes can be provided by using multiple projectors. Additional descriptions related to the splicing of display areas and the use of multiple projectors to increase the field of view are provided in U.S. Patent Application No. 2018011074 filed on March 21, 2018 (the disclosure of which is incorporated herein by reference in its entirety for all purposes).

[0040] In an embodiment, the fiber scanning projector 100 is fed by a fiber input 110 and the fiber oscillating region 120 and the optical assembly portion 130 are mounted in the outer edge of a frame as illustrated in FIG. 2 of U.S. Patent Application No. filed on March 21, 2018 (the disclosure of which is incorporated herein by reference in its entirety for all purposes). The output of the optical assembly portion 130 is oriented to emit light toward an input coupling element of an eyepiece mounted in the frame. As an example, light from the output of the optical assembly portion can be directed toward a user before it is coupled into the eyepiece, which can include a world side cover glass and an eye side cover glass.

[0041] Figure 1CSchematically illustrates an optical path in a viewing optical assembly (VOA) that can be used to present digital or virtual images to an observer according to an embodiment of the present invention. The VOA includes a projector 100 and an eyepiece layer 160 that can be worn around or in front of the observer's eyes. As discussed, the VOA can be integrated with the frame of a pair of glasses to present digital or virtual images to an observer wearing these glasses.

[0042] refer to Figure 1C , a fiber scanning projector 100 is illustrated. However, it will be understood that other scanning light systems or scanning beam systems may be utilized in conjunction with embodiments of the present invention, which may, for example, be implemented as a scanning waveguide system including a scanning waveguide source. Therefore, although optical fiber is illustrated as one embodiment for waveguide light in some embodiments, the present invention is not limited to fiber scanning systems and other waveguide scanning systems may be utilized according to other embodiments. Examples of other waveguide systems include microelectromechanical systems (MEMS) that integrate waveguide features (e.g., silicon waveguides integrated with cantilever beams) into light scanning systems. Moreover, a scanning mirror system may be used with embodiments of the present invention as described herein, in which a converging light beam is scanned by a projector to produce a curved object surface. In addition, a scanning point source (e.g., a light emitting diode (LED) or an organic LED (OLED)) may be used in conjunction with the optical devices described herein. As an example, in Figure 1D One embodiment of a MEMS based waveguide scanner is illustrated in FIG.

[0043] Although not shown in Figure 1C 100, but optional projector relay optics may be used to direct light from the fiber scanning projector 100 into the eyepiece layer 160. Since these projector relay optics are optional, they are not required by the present invention and other optical configurations may be utilized in accordance with embodiments of the present invention. In the illustrated embodiment, light exits the optical assembly portion in a direction generally perpendicular to the longitudinal axis of the mechanical housing 156 of the fiber scanning projector 100 and is collimated, which provides a suitable input for coupling into the grating 167.

[0044] During operation, an optical fiber 154 mechanically attached to the piezoelectric actuator 150 oscillates in the fiber oscillation region 120. In an embodiment, the piezoelectric actuator 150 includes four electrodes distributed at circumferential positions offset 90° relative to each other. Thus, positive and negative voltages applied to opposite sides of the piezoelectric actuator can cause the actuator and the scanning optical fiber to bend within the plane of the electrodes. By synchronously driving all four electrodes, oscillation of the optical fiber can be achieved. As light leaves the optical fiber 154 as it scans, it is coupled to the optical component portion 130, which redirects the light toward the eyepiece layer 160.

[0045] The fiber scanning projector 100 can provide multiple colors, including three primary colors (red, green, and blue (RGB)) to form a full-color display. Therefore, the eyepiece layer 160 may include one or more eyepiece layers. In one embodiment, the eyepiece layer 160 includes three eyepiece layers, one eyepiece layer for one of the three primary colors (red, green, and blue). In another embodiment, the eyepiece layer 160 may include six eyepiece layers, that is, a group of eyepiece layers for each of the three primary colors is configured to form a virtual image at one depth plane, and another group of eyepiece layers for each of the three primary colors is configured to form a virtual image at another depth plane. In other embodiments, the eyepiece layer 160 may include three or more eyepiece layers for each of the three primary colors for three or more different depth planes. Each eyepiece layer includes a planar waveguide and may include an in-coupling grating 167, an orthogonal pupil expander (OPE) region 168, and an exit pupil expander (EPE) region 169.

[0046] Still reference Figure 1C , the projector 100 projects the image light onto a coupling grating 167 in the eyepiece layer 160. The coupling grating 167 couples the image light from the projector 100 into the planar waveguide so that it propagates in a direction toward the OPE region 168. The waveguide propagates the image light in a horizontal direction by total internal reflection (TIR). The OPE region 168 of the eyepiece layer 160 also includes a diffraction element that couples and redirects a portion of the image light so that it propagates in the planar waveguide toward the EPE region 169. The EPE region 169 includes a diffraction element that couples and guides a portion of the image light so that it propagates in the waveguide toward the observer's eye 162 in a direction approximately perpendicular to the plane of the eyepiece layer 160. In this way, the image projected by the projector 101 can be observed by the observer's eye 162.

[0047] As described above, the image light generated by the projector may include light in three primary colors, i.e., blue (B), green (G), and red (R). Such image light may be separated into constituent colors (e.g., temporally or spatially) such that image light of each constituent color may be coupled to a corresponding waveguide in the eyepiece.

[0048] Figure 1D A partial cross-sectional view of a waveguide scanning system using a silicon-based waveguide according to an embodiment of the present invention is shown. In this embodiment, rather than using a tapered optical fiber as the optical scanning element, a MEMS scanner 170 comprising a cantilever beam comprising a silicon-based cantilever waveguide is utilized.

[0049] exist Figure 1DIn the embodiment illustrated in FIG. 1 , light for display through the eyepiece is provided using an optical fiber (not shown) optically coupled to a waveguide 174 supported by a cantilever beam 172. The cantilever beam 172 extends from a support structure 176 that is mechanically attached to the mechanical housing 156. Thus, light from the optical fiber can propagate down the waveguide, be emitted, and be received by the optical assembly portion 130. As shown with respect to FIG. Figure 2A More fully described, the optical assembly portion 130 includes a prismatic element 210 and a collimating element 220 coupled at an interface, which defines a beam splitter 214. Figure 1D , light emitted from waveguide 174 may pass through beam splitter 214, pass through a quarter wave plate (not shown), and be incident on collimating surface 224. After reflection, the light passes through the quarter wave plate a second time and reflects off beam splitter 214 as illustrated by ray 180a.

[0050] To actuate the cantilever beam 172, Figure 1D The optical scanner illustrated in FIG. 1 includes a transducer including a frame 180 and a hub 182 driven by a piezoelectric strip 184. The piezoelectric strip is coupled to the frame 180 and the hub 182 to cooperatively induce oscillation of the cantilever beam 172 in a predefined pattern. A bracket 186 can be configured to position the cantilever beam 172, the frame 180, and the hub 182 relative to the optical assembly portion 130. Moreover, the bracket 186 can be mechanically coupled to the mechanical housing 156.

[0051] As in Figure 1D , the hub 182 can be configured to rotate in situ to achieve a desired scanning pattern of the cantilever beam 172. For example, sequential actuation of the piezoelectric strips 184 may cause longitudinal extension and contraction of the piezoelectric strips such that the hub is steered in a mode that oscillates the cantilever beam 172 (particularly the waveguide tip) in a spiral scanning pattern. In other embodiments, the hub 182 can be configured to move laterally and / or vertically to induce a desired scanning pattern, for example, a raster scanning pattern. Although a hub 182 having a circular shape is depicted, it should be understood that many other shapes (such as elliptical, rectangular, and other polygonal gap geometries) are possible.

[0052] The cantilever beam 172 can be formed according to the length of silicon or silicon carbide. The waveguide 174 (which can be a single-mode waveguide) can be formed using semiconductor processing steps that define the refractive index difference supporting the waveguide. Although the cantilever beam 172 is illustrated as including a single waveguide 174, other embodiments can implement multiple waveguides supported by the cantilever beam. It should be understood that the cantilever beam 172 can also be used in conjunction with other actuators (e.g., the piezoelectric actuator 150 described more fully herein). Therefore, Figure 1D The frame and hub embodiments illustrated in FIG. 5 are merely exemplary structures that may be used to actuate the cantilever beam.

[0053] Figure 1E 800 is a partial cross-sectional view illustrating the structure of an eyepiece according to an embodiment of the present invention. The area shown in the cross-sectional view includes the area of ​​the eyepiece 800 that couples into a diffractive optical element (e.g., a coupling grating). Figure 1E As shown in , eyepiece 800 includes a stack of waveguide plates 820, 830, and 840 that receive input light from a fiber scanning projector and output image information to the observer's eye 802. Figure 1E The eyepiece 800 illustrated in FIG. 8 includes an eye-side cover layer 810 located on a side of the eyepiece adjacent to an observer's eye, and a world-side cover layer 850 located on a side of the eyepiece facing the world.

[0054] In some embodiments, the waveguide plates 820, 830, and 840 include respective planar waveguides 822, 832, or 842 for propagating light within the plane of their respective waveguide plates 820, 830, and 840. Each planar waveguide 822, 832, or 842 has a rear surface facing the observer's eyes, and a front surface facing the world. Figure 1E In the embodiment illustrated in , the waveguide plates 820 , 830 and 840 further include a corresponding grating 824 , 834 or 844 disposed on the rear surface of their corresponding waveguide 822 , 832 or 842 for coupling and redirecting a portion of the light propagating in their corresponding waveguide 822 , 832 or 842 .

[0055] In the illustrated embodiment, each waveguide 822, 832, or 842 and each grating 824, 834, or 844 can be wavelength selective, such that it selectively propagates or redirects light within a given wavelength range. In some embodiments, each of the waveguide plates 820, 830, and 840 can be configured for a corresponding primary color. For example, waveguide plate 820 is configured for red (R) light, waveguide plate 830 is configured for green (G) light, and waveguide plate 840 is configured for blue (B) light. It will be understood that the eyepiece 800 may include two or more waveguide plates for red light, two or more waveguide plates for green light, and two or more waveguide plates for blue light as described above for different depth planes. In some other embodiments, other colors (including magenta and cyan) may be used in addition to or may replace one or more of red, green, or blue.

[0056] To improve optical efficiency, some embodiments utilize a reflective surface, such as metallization of a surface on one of the surfaces of the eye-side cover layer (e.g., the front surface) to provide a highly reflective surface (e.g., ~100% reflective coating) of a reflective structure formed behind an input coupling element (e.g., a vertically aligned in-coupling grating) to reflect input light, which may be RGB light, that passes through the input coupling element and creates a second pass through the input coupling element to improve image brightness. As in Figure 1E As illustrated in , the reflector 812 reflects the input light 801 incident from the fiber scanning projector that is not coupled into the waveguide. After reflecting from the reflector 812, the input light is able to make a second pass through the input coupling element and increase the amount of light coupled into the waveguide.

[0057] In an alternative embodiment, an annular reflector 852, for example made using a 100% reflective metal coating, can be placed on the world side cover glass. Although the annular reflector 852 is shown on the back side of the world side cover layer 850, this is not required by the present invention and it can be alternatively mounted on the front side. Those of ordinary skill in the art will recognize many variations, modifications and substitutions. In this alternative embodiment, the input light 801 from the fiber scanning projector passes through the center of the annular reflector 852 after it is output from the optical component portion of the fiber scanning projector. Since the input light is divergent, the beam spreads as it passes through the eyepiece and reflects from the reflector 812 behind the input coupling element. The reflected light 804 propagates back through the eyepiece, where the light cone expands during propagation. In some embodiments, the reflected light 804 is also coupled into the coupling grating during the return path characterized by the same orientation as the input beam for display to the observer, because although the reflected light 804 is a mirror image of the input light 801, the entry through the opposite side of the coupling grating results in the same orientation. A significant portion of the light (which may be a majority) reflects from the annular reflector 852 on the world side cover layer, as illustrated by the doubly reflected light 806, and is able to make a third pass through the input coupling element, which results in additional coupling of light into the waveguide plate. As will be apparent to one skilled in the art, a Hall of Mirrors effect may be achieved, which results in increased brightness associated with the increased number of rays passing through the eyepiece, which improves fill factor and image quality.

[0058] Channels can be inserted into the temples and frames to accommodate optical fibers and electrical wiring. When the optical fibers / wiring pass through the spring hinges, the design dimensions are such that the optical fibers cannot bend past the minimum bending radius of curvature when the temples are folded.

[0059] In addition to relative to Figure 1EIn addition to the reflective structures associated with the input coupling elements discussed, some embodiments utilize a partially reflective (e.g., 50% aluminized) surface on the inside surface of the world-side cover glass so that a portion (e.g., half) of the light propagating from the eyepiece toward the world is reflected and directed back toward the user's eye, which increases overall brightness and increases beam density as a result of a slight lateral shift of the beam, which contributes to an improved fill factor.

[0060] Figure 2A is a ray tracing diagram illustrating the propagation of light through an optical component portion according to an embodiment of the present invention. The optical component portion 130 includes a prismatic element 210 and a collimating element 220 coupled at an interface. In an embodiment, the prismatic element and the collimating element are optically combined at the interface. As described more fully herein, one or more of the surfaces of the optical component portion 130 may include optical power. Therefore, while the collimation of light in terms of the collimating surface 224 is discussed herein, it will be understood that surfaces other than the collimating surface 224 may contribute to the collimation of light through the system. The scanning fiber 154 in the fiber oscillation region 120 is illustrated at three scanning positions: on the axis 230 (solid line), off-axis to the right 232 (dashed line), and off-axis to the left 234 (dashed line). As shown in Figure 2A As it oscillates, the tip of the scanning fiber sweeps across the Figure 2A , which results in a convex surface being imaged such that curve 240 may be referred to as a convex object surface. Conventional lenses are typically designed for either a flat object plane or a concave object surface. Embodiments of the present invention utilize a design in which a convex object surface 240 associated with the tip of the scanning optical fiber 152 is matched with a concave collimating surface 224, which at a high level may be a substantially spherical mirror having a radius of curvature that is twice the radius of curvature of the convex object surface 240. Thus, in some embodiments, most of the focusing is achieved using the convex collimating surface 224, which may be implemented as a curved mirror with an aspheric correction term. Although in Figure 2A 2 and 3 illustrate refractive and reflective elements, but embodiments of the present invention are not limited to these implementations, and embodiments of the present invention may utilize diffractive surfaces, meta surfaces, etc. For example, in addition to a reflective surface, the collimating surface 224 may be a diffractive surface, a meta surface, etc. Figure 2A One or more of the other surfaces illustrated in the drawings may also be implemented using a diffractive structure or a combination of diffractive and / or refractive structures. Examples would be diffractive structures to compensate for chromatic aberration and refractive structures to focus / defocus the beam. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0061] In addition to scanning optical fibers, other optical systems can be used to form the convex object surface 240. Examples of these optical systems include other waveguide scanning systems, including MEMS-based scanning systems, scanning mirror systems with converging beams, scanning point sources, flat panel displays combined with optics to produce curved object surfaces, and the like.

[0062] Embodiments of the present invention enable the optical prescription of various optical surfaces to be varied to optimize size, exit pupil diameter, combined power, linear magnification, angular magnification, distance between exit pupil and output surface, etc. Control of the curvature of input surface 212, collimating surface 224, and output surface 226 enables various properties of the output beam to be controlled, including beam diameter, angular magnification of the angle associated with fiber deflection (i.e., the angle between scanning positions 232 and 234), etc. It should be noted that in some embodiments, beam splitter 214 can include curvature so that it is not a flat surface, thereby providing additional design freedom. The non-planar shape (i.e., non-planar curvature) can include curvature (e.g., concave or convex) to introduce power, compensate for aberrations, etc. In addition, the refractive index of the material used to manufacture optical component portion 130 can be adjusted to modify the optical properties discussed above. Moreover, beam splitter 214 can be a partially reflective (50 / 50 split) surface, a polarizing beam splitter, a wavelength selective beam splitter, etc.

[0063] refer to Figure 2A , if the polarizing beam splitter 214 has a varying polarization (e.g., alternately passing and reflecting incident light as a function of time), a multiplexing function can be achieved. A shutter integrated into the optical path between the partially reflecting surface / polarizing beam splitter and the collimating surface 224 / surface 227 can be used to multiplex between the two optical paths. Thus, some embodiments provide a multiplexed display having a high-resolution, narrow field of view image surrounded by a low-resolution, wide field of view image. In some embodiments, surface 227 can be absorptive, providing a shutter effect when light is reflected from the polarizing beam splitter 214 toward surface 227. Those of ordinary skill in the art will recognize many variations, modifications, and alternatives.

[0064] Again, reference Figure 2A , the scanning fiber 154 acts as a point source of light, emitting cones of light. These cones of light are shown as they propagate from the convex object surface 240 through the optical component portion 130. As the scanning fiber sweeps through the oscillation pattern, different pixels are illuminated to form the desired image. Figure 2AIn the embodiment illustrated in , light from the scanning fiber is polarized so that after it enters the optical component portion 130 through the input surface 212, it will pass through the polarizing beam splitter 214 with little reflection, pass through the quarter wave plate and be incident on the collimating surface 224. After reflection, the light passes through the quarter wave plate 222 a second time and reflects off the polarizing beam splitter 214 toward the output surface 226. An exit pupil 228 is formed outside the optical component portion 130 for delivery to the eyepiece. As will be apparent to those skilled in the art, for many optical systems, alignment between the exit pupil and the input plane of another optical system is preferred. Therefore, the working distance between the output surface 226 and the exit pupil 228 enables embodiments of the present invention to be utilized in conjunction with a wide variety of optical systems. As an example, if the light emitted by the fiber scanning projector is utilized by a waveguide-based optical system, the input coupling element of the waveguide-based optical system can be placed in line with (e.g., coplanar with) the exit pupil 228. In embodiments, providing an exit pupil 228 where a small diameter beam is formed can enable efficient coupling into a small input coupling element that can be matched in size to the exit pupil, thereby efficiently utilizing the area of ​​the waveguide-based optical system. Figure 2A As illustrated in , the three light cones emitted at each of the three illustrated positions 230, 232 and 234 of the scanning optical fiber 154 are collimated as they leave the optical component portion as shown, for example, by collimated light rays 231 and 233, which define the edge of the light cone at the on-axis position 230.

[0065] In another specific embodiment, the polarizing beam splitter can be replaced with a wavelength selective beam splitter such that one or more colors will pass through the beam splitter while the other(s) colors are reflected toward surface 227, which can be implemented as a surface with refractive power. This wavelength selectivity will enable focusing through the use of diffractive elements or metasurfaces, as diffractive optics are used as a replacement for refractive optics. Thus, embodiments of the present invention may integrate metasurfaces on one or more of the input surface 212, collimating surface 224, surface 227, and / or output surface 226 to encode multiple lens functions into the metasurface for wavelength selective optical processing, other diffractive optical functions, dispersion compensation, etc. In some designs, dispersion correction is provided by various surfaces, for example, dispersion compensation can be achieved by aberration correction provided on the output surface by correcting aberrations occurring at the input surface.

[0066] As compared to Figure 2B As discussed in additional detail, the quarter wave plate may also be fabricated by vacuum forming on the collimating surface 224. In this embodiment, after formation of the quarter wave plate on the curved surface, a metallization or other suitable reflective surface may be formed to complete the fabrication of the collimating surface.

[0067] In an embodiment, the input surface 212, collimating surface 224, and output surface 226 of the optical component portion 130 can have refractive power to compensate for spherical aberration and provide magnification of the field of view in some embodiments. Therefore, a smaller deflection of the optical fiber in the fiber oscillation region results in a larger field of view. As an example, the input surface 212 can be convex relative to the input light to provide positive refractive power, the collimating surface 224 can be concave relative to the light from the input surface to provide negative refractive power, and the output surface can be convex relative to the light from the beam splitter to provide negative refractive power. The collimating surface 224 is substantially spherical, but includes an aspheric curvature in some embodiments. The aspheric curvature can correct spherical aberration, and the overall curvature can result in collimation of light by the collimating surface. The collimating surface 224 can be manufactured as a reflective element by deposition of one or more reflective coatings, metallized coatings, etc.

[0068] It should be noted that while the collimating surface 224 may have a radius of curvature that is approximately twice that of the convex object surface 240 (which may also be referred to as a curved object surface), in some embodiments, this is not required by the present invention, and the input surface 212 and the output surface 226 may contain optical power in addition to that present in the collimating surface 224. Thus, the curvature of the collimating surface 224 may deviate from twice the curvature of the convex object surface 240 due to the additional optical power being realized by the input surface 212 and the output surface 226. Furthermore, as used herein, aspheric components may be integrated into optical surfaces, including the input surface 212, the collimating surface 224, and the output surface 226.

[0069] In an exemplary manufacturing process, the optical assembly portion 130 is manufactured by bonding three elements together. In this process, the first element is a prism element 210, and the second element is a collimating element 220 bonded to the prism element. The prism element 210 receives light through an input surface 212. A polarizing beam splitter 214 is formed at the interface of the prism element 210 and the collimating element 220. In some embodiments, a polarization selective coating is applied to the longest surface of the prism before bonding to form a polarizing beam splitter. A quarter wave plate 222 is formed on the rear surface of the collimating element 220, and a third element including a curved reflective optical device 221 is bonded to the quarter wave plate. As described herein, the curved reflective optical device 221 includes a collimating surface 224, which can be metallized or otherwise coated to provide high reflectivity.

[0070] During operation, using polarized light at the input, most of the polarized input light will pass through the polarizing beam splitter 214 on a first pass, pass through the quarter wave plate 222, be reflected and collimated by the collimating surface 224, pass through the quarter wave plate 222 a second time (now with an orthogonal polarization state) and be substantially reflected from the polarizing beam splitter toward the output surface 226.

[0071] Figure 2B is a side view of an alternative optical assembly portion according to an alternative embodiment of the present invention. Figure 2A and 2B , Figure 2A The collimating element 220 and the curved reflective optical device 221 illustrated in FIG. 2 have been combined into a single (i.e., monolithic) collimating reflector 251 to form an alternative optical portion 250. The reflective surface 252 includes a wave plate that introduces a half-wave phase shift upon reflection. In one embodiment, a quarter-wave plate is formed on the right edge of the collimating reflector 251 before the reflective surface 252 is formed, for example, by depositing a metal film, a dielectric film, etc. In other embodiments, a microstructure may be used to introduce a half-wave phase shift upon reflection. Therefore, the alternative optical portion 250 is not limited to a specific manner of achieving phase delay and reflection. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0072] Figure 2C260, and additional optical elements 262, 263, and 264 are cast onto the outer surface of the beam splitter cube 261 to form the input surface, the collimating surface, and the output surface, respectively. In this embodiment, a quarter wave plate can be implemented at the intersection of the beam splitter cube 261 and the optical element 263 forming the collimating surface. In an alternative embodiment, surface 266 can be used to define the collimating surface of the optical element 263, which results in alignment between the edge of the optical element 263 and the surface 267 of the optical element 264. In this alternative embodiment, it can be noted that the optical element 263 can be trimmed at the periphery to form an element with a non-circular plan view (including a rectangular plan view). Therefore, the optical element 263 has a trimmed surface or edge aligned with the surface 268 of the beam splitter cube 261. This alignment between the edges of the various elements can facilitate registration during manufacturing, including the bonding of the various elements. The use of a glass beam splitter cube 261 provides advantages including the choice of polarization selective coatings for fabricating the beam splitter surface 265. In addition, due to the wide availability of glass beam splitter cubes (including beam splitters), manufacturability is enhanced by this design. In other embodiments, beam splitters of materials other than glass (including plastics) are utilized. In addition to forming optical elements (e.g., refractive and reflective optical elements) by casting, other techniques can be used to achieve the optical effects, including molded elements, conventionally manufactured optics, use of diffractive surfaces and / or metasurfaces, etc.

[0073] Figure 2D is a side view of another alternative optical assembly portion according to an alternative embodiment of the present invention. Figure 2D In an alternative embodiment of the optical component portion 270 illustrated in , the polarization selective coating for the polarizing beam splitter is removed along with the quarter wave plate. In this alternative embodiment, a partially reflective surface 271 (e.g., a 50 / 50 reflector) combines the prismatic element to the collimating element 273. Half of the light incident from the input surface 212 is passed to the collimating surface 224 and reflected back toward the partially reflective surface 271 that combines the prismatic element 272 and the collimating element 273. The other half of the light is reflected toward the reflective surface 274, which in this alternative embodiment can have the same curvature as the collimating surface 224. Therefore, the light reflected from the collimating surface and the light reflected from the reflective surface 274 are collimated (given the refractive power of the output surface 226). Figure 2D The embodiment illustrated in FIG. 2 can improve optical efficiency because light reflected from reflective surface 274 is available for output from the optical component portion. In an embodiment, a single exit pupil is shared by light reflected from collimating surface 224 and light reflected from reflective surface 274, relative to Figure 2E Discussed as a superimposed exit pupil.

[0074] With this design, different refractive powers can be achieved using the collimating surface 224 and the reflective surface 274, which can have different curvatures, which results in a zoomed in / magnified view, wide / narrow field of view, etc. when light is directed to each of these surfaces in a multiplexed manner. As an example, the reflectivity of the partially reflective surface 271 can be varied to provide time-based multiplexing.

[0075] A multiplexing function can be achieved because the partially reflective surface 271 can have a varying reflectivity, alternately passing and reflecting incident light. A shutter integrated into the optical path between the partially reflective surface 271 and the collimating surface 224 / reflective surface 274 can be used to multiplex between the two optical paths. Therefore, some embodiments provide a multiplexed display with a high-resolution, narrow field of view image surrounded by a low-resolution, wide field of view image. Those of ordinary skill in the art will recognize many variations, modifications and substitutions.

[0076] In another embodiment, a stitched image can be formed by tilting the partially reflective surface 271 at an angle other than 45° relative to the incident light. Light passing through the partially reflective surface 271 will be reflected from the collimating surface 224 and directed in a first direction after passing through the output surface 226. Light reflected from the partially reflective surface 271 will be reflected from the reflective surface 274 and directed in a second direction after passing through the output surface 226. Thus, light reflected from the collimating surface 224 may be tilted to the left after passing through the output surface 226 and light reflected from the reflective surface 274 may be tilted to the right after passing through the output surface 226, thereby providing input directed to different portions of the image field for a stitched display embodiment.

[0077] Figure 2E 284 and 285. FIG. 285 is a side view of a portion of a multi-polarization tilted reflector optical assembly according to an alternative embodiment of the present invention. In this embodiment, the polarization-sensitive material forms a polarization beam splitter 283 at the interface of the prism element 284 and the collimating element 285, similar to Figure 2AWith the polarization beam splitter 214 in FIG. 2 , the input light from the fiber scanning projector can have two signals encoded with different polarizations. A first input beam 286 encoded with a first polarization can pass through the polarization-sensitive material of the polarization beam splitter 283 to reflect off the collimating surface 224. This beam will form an exit pupil 281. A second input beam 287 encoded with a second polarization will reflect from the polarization-sensitive material of the polarization beam splitter 283 to reflect off the reflective surface 289. This beam will form an exit pupil 282. Because the interface of the prism element 284 and the collimating element 285 is tilted at an angle other than 45° relative to the input beam, the exit pupils 281 and 282 can be spatially offset. As an example, if the polarization beam splitter 283 is color selective, the exit pupil associated with the first color (e.g., green) can be positioned adjacent to the exit pupil associated with the second color (e.g., red) so that the exit pupils can provide spatially separated beams for the input to the eyepiece. In addition to the example of FIG. 2 , the exit pupil 281 and the collimating element 285 can be spatially offset. Figure 2E In addition to the spatial separation in the z-direction illustrated in FIG, the exit pupils may be spatially separated in the x-direction or the y-direction.

[0078] Thus, two overlapping images can be generated, or used as in Figure 2E The angled surfaces at the interface of the prism element 284 and the collimating element 285 illustrated in , can form two spatially separated images in the image field. Thus, two laterally separated exit pupils can be provided, which can provide inputs for two input coupling elements on the waveguide display. As discussed herein, the curvatures of the collimating surface 224 and the reflective surface 289 can be different. For example, in a wavelength selective embodiment, a wavelength selective beam splitter can be used that will pass a first color to reflect from the collimating surface 224. The second color will be reflected from the polarizing beam splitter and then reflected from the reflective surface 289, thereby producing a beam of the second color that diverges or converges after reflecting from the reflective surface 289. This can allow, for example, spatial separation between two different color channels for subsequent coupling into two different coupling-in gratings each associated with a different waveguide layer of the eyepiece. In addition, these designs can be extended to a multi-depth plane embodiment in which multiple beams at each color are used to provide, for example, M beams at N colors for coupling into MxN waveguides. Integration of a quarter wave plate can be achieved in a polarization sensitive embodiment. Thus, a polarization selective reflector may be implemented in conjunction with spatial separation of the pupil to enable routing of one color to a first depth plane and a second color to a second depth plane.Thus, both wavelength separation as well as polarization separation are included within the scope of the present invention.

[0079] In other embodiments, the exit pupils may be arranged at the same position (ie, superimposed). Figure 2EThe illustration of the spatially separated pupils in is only an example and should not be construed as limiting embodiments of the present invention. Those skilled in the art will recognize many variations, modifications, and substitutions.

[0080] Relative to Figure 2A-2E One or more of the optical surfaces discussed can be variable focus and its focus can be controlled in conjunction with input from the fiber scanning projector. Therefore, light injected into the optical component part at different angles can experience different refractive powers. In this embodiment, a multi-focal display can be realized according to the field angle. Moreover, additional optical elements can be integrated with the structure described herein, for example, between the output surface and one or more exit pupils or optically downstream of one or more exit pupils. These additional optical elements, which may include relay optical devices, may have variable refractive powers, for example, a variable focus lens located between the output surface and one or more exit pupils. Therefore, a collimated beam can be focused, aberrations can be corrected, other optical effects can be achieved, etc. In some embodiments, the shape of the convex object surface 240 can be changed from a spherical and variable focus surface, or additional optical elements can be used for the curvature of the convex object surface as appropriate. Various materials can be used to manufacture the structures illustrated herein, including materials that change their refractive index according to an applied bias, including liquid crystal lenses, electro-optic polymers, lithium niobate, etc. Since the fiber scanning projector can scan at high frequencies, optical materials that can change their optical properties at high frequencies are suitable for use in various embodiments. As an example, an optical structure that can rapidly modulate the focal length can work with a fiber scanning projector to change the focus on a line-by-line basis or on a pixel-by-pixel basis. These materials can be utilized in conjunction with the input surface and / or output surface of the optical component portion and in conjunction with the collimating surface 224. As an example, a deformable mirror can be integrated as an element of the collimating surface 224 or a replacement for the collimating surface 224. Such a deformable mirror operating at kilohertz rates and above can provide variable focus operation on a line-by-line basis or on a pixel-by-pixel basis as appropriate for a particular application.

[0081] exist Figure 2E The maximum distance that the prismatic element 284 extends in the z-direction, as marked at point A in FIG. 1 , may vary depending on the particular implementation. Figure 2E As shown in FIG. 1 , point A is the intersection of the right side of collimating element 285 and the bottom of prismatic element 284. Figure 2A When the substantially spherical surface is shown by the curve 240 in FIG. Figure 2EThe design illustrated in enables a wide field of view. In other embodiments, the surface of the prismatic element 284 forming the upper right edge of the prismatic element is tilted so that point A moves to a reduced value in the z direction. In a similar manner, point B can move to a larger value in the x direction as the left side of the prismatic element 284 is extended and the left side of the collimating element 285 is reduced. Those of ordinary skill in the art will recognize many variations, modifications and alternatives.

[0082] Figure 2F 2 is a side view of an optical assembly including a Mangin reflector in accordance with an embodiment of the present invention. Similar to one or more of the designs discussed above, a beam splitter cube 261 is used as the basis for a beam splitter cube based optical assembly portion 290. A quarter wave plate 291 is implemented at the intersection of the beam splitter cube 261 and a Mangin reflector 292, which provides collimation of the input beam. In the illustrated embodiment, the output lens 293 is implemented as an achromatic doublet, although other lens configurations may be used in accordance with embodiments of the present invention.

[0083] Figure 2G is a side view of an optical assembly including a Mangin reflector according to an alternative embodiment of the present invention. Figure 2G In the embodiment illustrated in FIG. 2 , a beam splitter cube 261 is used as the basis for a beam splitter cube based optical assembly portion 294. A quarter wave plate 291 is implemented at the intersection of the beam splitter cube 261 and a Mangin mirror 292, which provides collimation of the input beam. In the illustrated embodiment, the output lens 295 is implemented as a molded glass lens, although other lens configurations may be used in accordance with embodiments of the invention.

[0084] Figure 2H 2 is a side view of an optical assembly including a 3D printed lens according to an embodiment of the present invention. Similar to one or more of the designs discussed above, a beam splitter cube 261 and a quarter wave plate 192 are utilized in an optical assembly portion 296. In this embodiment, an input lens 299 and an output lens 295, which may be molded glass lenses, are utilized. The collimating optics (also referred to as a printed lens) are formed using 3D printing (also referred to as additive manufacturing). The collimating optics include a substrate 297 that supports a printed lens 298 (e.g., a polymer lens formed with a curvature associated with a Mangin lens). The substrate 297 is bonded to the quarter wave plate, for example, using an optical adhesive.

[0085] It should be noted that reference Figures 2A-2H Any characteristics of any of the components and surfaces discussed or illustrated apply as appropriate Figures 2A-2HThe embodiments provided in any of the other embodiments illustrated in . By way of example only, the curvature of the surface, the reflective or diffractive properties of the surface, the polarization properties, etc. are applicable to any of the embodiments as appropriate.

[0086] Figure 3 1 is a simplified perspective view of the optical assembly portion of a fiber scanning projector according to an embodiment of the present invention. The optical assembly portion 130 includes a prism element 210 to a collimating element 220. Light is incident on an input surface (not shown, but facing left and back) and propagates toward a polarizing beam splitter 214. Also illustrated in this view are the edges of a quarter wave plate 222, a collimating surface 224, and an output surface 226.

[0087] In some embodiments, the fiber scanning projector can achieve an angular resolution of 3 arc minutes and a 4x 3 aspect ratio with a 50° diagonal field of view, although these specific parameters are not required by the present invention. In some embodiments, a 60°×30° elliptical field of view is achieved. In another embodiment, the fiber scanning projector can achieve an angular resolution of 2 arc minutes and a 4x 3 aspect ratio with a 50° diagonal field of view. In yet another embodiment, the fiber scanning projector can achieve an angular resolution of 1 arc minute or less. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0088] To reduce the size and weight of the fiber scanning projector, the portion not supporting the light can be trimmed, forming a wedge-shaped structure that also increases packaging flexibility, particularly for integration with eyeglasses with curved frames.

[0089] Figure 4 is a simplified perspective view of elements of an optical assembly portion during manufacture according to an embodiment of the present invention. Figure 4 , a first element 410 of the optical assembly portion includes a collimating optics portion 412 that includes the propagation path of light after passing through the beam splitter, the collimating surface 224, and the output surface 226. A second element 420 of the optical assembly portion includes a surface 422 on which a prism of a polarizing beam splitter may be formed. In this perspective view, the input surface is not shown as it faces rearward and left. Alignment features 430 are integrated into the material and are designed to match corresponding alignment features (not shown) on the lower left surface of the first element.

[0090] In some embodiments, the second element 420 is fabricated from a glass material to facilitate the formation of a polarization beam splitter at the interface of the first element and the second element, as glass materials may be more suitable for deposition of polarization selective coatings than some plastic materials.

[0091] Figure 5 is a simplified schematic diagram illustrating a fiber scanning projector 500 according to an alternative embodiment of the present invention. Figure 5 , the scanning fiber 510 passes through a hole 522 in the reflector 520. The scanning fiber is illustrated at the end of the range of motion. The collimating reflector 530 reflects the light emitted by the scanning fiber, which then reflects from the reflector 520 to provide an output beam 540. In some embodiments, the radius of curvature of the collimating reflector 530 is twice the radius of curvature of the spherical object surface 512.

[0092] As discussed with respect to the fiber scanning projector, when the scanning optical fiber 510 is actuated by the piezoelectric element 514, it scans a substantially spherical surface 512, also referred to as a spherical object surface. Therefore, after reflecting off a substantially spherical reflector having a radius of curvature twice that of the surface scanned by the scanning optical fiber, light emitted from any point along the surface scanned by the scanning optical fiber will be well collimated after reflecting from the substantially spherical reflector.

[0093] Since the base of the fiber scanner is adjacent to the piezoelectric element 514, the deflection of the scanning fiber 510 at the aperture 522 is small, although the deflection at the tip of the scanning fiber is large (e.g., about 20 degrees). When the beam is emitted from the tip of the scanning fiber, it fans out to form a beam as shown in FIG. Figure 5 516. Collimation of the light cone by the collimating mirror 530, which is a substantially spherical reflector, provides a beam having a diameter much larger than the diameter of the scanning optical fiber, so that most of the reflected light is reflected from the mirror 520, with little light passing through the hole 522 in the return path.

[0094] In some embodiments, the field of view of the fiber scanning projector 500 is a function of the portion of the arc that the scanning fiber 510 subtends during oscillation. As an example, if the scanning fiber sweeps 20 degrees, the field of view of the projector is about 20 degrees. The increase in the field of view can be achieved by increasing the range of the fiber oscillation. In other embodiments, the magnification of the effective field of view can be used to increase the field of view independently of the range of the fiber oscillation. Comparing the fiber scanning projectors in Figures 2 and 5, in view of the field of view associated with the fiber scanning projector 500 as a result of the collimation caused by the reflection from the reflector 530 is maintained, the optical component portion 130 provides the illustrated optical surface, which can be used to introduce a magnification that can increase the field of view produced by the projector. As an example, the modification of the curvature of the output surface 226 can be used to enlarge the field of view.

[0095] As illustrated herein, embodiments of the present invention utilize designs related to the use of a spherical object plane and a corresponding reflector having a curvature that is approximately twice the curvature of the spherical object plane.

[0096] Fig. 6A A fiber scanning projector according to an alternative embodiment of the present invention is illustrated. Fig. 6AThe fiber scanning projector 600 in FIG. 6 includes a scanning optical fiber 610 passing through and mechanically coupled to a piezoelectric element 605, a first polarization-sensitive reflector 620, and a second polarization-sensitive reflector 630. A quarter-wave plate 622 is integrated with the first polarization-sensitive reflector.

[0097] In operation, light emitted by the scanning optical fiber 610 has a polarization that passes through the first polarization-sensitive reflector 620 and the quarter-wave plate 622. The second polarization-sensitive reflector 630 reflects the incident light, which passes through the quarter-wave plate 622 a second time, and, therefore, is reflected from the first polarization-sensitive reflector 620 because the polarization of the light is now oriented in an orthogonal direction. After reflecting from the first polarization-sensitive reflector 620, the light passes through the second polarization-sensitive reflector 630 as an output beam 640. As shown in Fig. 6A As illustrated in FIG. 6 , the second polarization-sensitive reflector 630 is bent using curvature to collimate the light emitted by the scanning optical fiber 610. Thus, a divergent input beam is converted into a collimated output beam.

[0098] Although Fig. 6A The optical elements illustrated in FIG. 6 are illustrated as being separated by air gaps, for example, the first polarization-sensitive reflector 620 and the second polarization-sensitive reflector 630 are separated by an air gap G, but this is not required by the present invention. As an example, a solid laminated component may be utilized that includes a first polarization-selective reflector, a quarter-wave plate, and a second polarization-selective reflector and receives light from a scanning optical fiber, transmits the light to a laminated curved reflector, performs polarization rotation, and then reflects the light from the first polarization-selective reflector. Thus, a solid element that may also include refractive power may be used to provide focusing / defocusing of light and aberration correction.

[0099] Figure 6B is an alternative fiber scanning projector according to an embodiment of the present invention. Fig. 6A The optical fiber scanning projector 601 shown in FIG. Fig. 6A The fiber scanning projector 600 illustrated in FIG. 6 shares some similarities and is similar to Fig. 6A The descriptions provided in the Figure 6B Fiber optic scanning projector 601 is shown in FIG.

[0100] refer to Figure 6B , the fiber scanning projector 601 comprises: a scanning optical fiber 610; a first polarization-sensitive reflector 621 that is bent to provide collimation; and a second polarization-sensitive reflector 631 that is substantially planar. A quarter wave plate is integrated with the first polarization-sensitive reflector.

[0101] In operation, light emitted by the scanning optical fiber 610 has a polarization that passes through the first polarization-sensitive reflector 621 and the quarter-wave plate. The second polarization-sensitive reflector 631 reflects the incident light, which passes through the quarter-wave plate a second time, and therefore, is reflected from the first polarization-sensitive reflector 621 because the polarization of the light is now oriented in an orthogonal direction. After reflecting from the first polarization-sensitive reflector 621, which collimates the light during reflection, the light passes through the second polarization-sensitive reflector 631 as an output beam 640. Compare Fig. 6A and 6B , Fig. 6A The folded optical path shown in the figure can be used as Figure 6B A potential shorter optical path alternative is illustrated in , but has the common feature of collimation.

[0102] Figure 6C is another alternative fiber scanning projector according to an embodiment of the present invention. Figure 6C The optical fiber scanning projector 602 shown in FIG. Figure 5 The optical fiber scanning projector 500 and Fig. 6A The fiber scanning projector 600 illustrated in FIG. 6 shares some similarities and is similar to Figure 5 and 6A The descriptions provided apply where appropriate to Figure 6C Fiber optic scanning projector 602 is shown in FIG.

[0103] exist Figure 6C In the embodiment illustrated in FIG. 6 , the scanning optical fiber 610 passes through a hole 652 in a curved mirror 650. A polarization-selective reflector 654 reflects the light during the first pass toward the curved mirror 650. By integrating a quarter-wave plate in the optical path, the light passes through the polarization-selective reflector 654 during the second pass after being reflected and collimated from the curved mirror 650. Figure 6C The embodiments illustrated in enable compact configuration in hybrid designs.

[0104] As illustrated by the optional lens 656, embodiments of the present invention enable additional optical elements to be placed at a significant distance from the elements that make up the fiber scanning projector. In this example, the distance D between the surface of the polarization selective reflector 654 and the lens 656 provides a working distance suitable for inserting a field of view amplifier, for example. In addition, given the suitable extended working distance provided by this embodiment, a spherical aberration corrector can be inserted.

[0105] Fig.6D It is yet another alternative fiber scanning projector according to an embodiment of the present invention. Fig.6D The fiber scanning projector shown in FIG. Figure 5 The optical fiber scanning projector 500 and Fig. 6AThe fiber scanning projector illustrated in FIG. shares some similarities and is relatively Figure 5 and 6A The descriptions provided apply where appropriate to Fig.6D Fiber optic scanning projector 603 shown in FIG.

[0106] refer to Fig.6D , the scanning fiber 610 passes through the hole 662 in the plane mirror 660. The curved polarization selective reflector 664 reflects the light toward the plane mirror 660 during the first pass. By integrating a quarter wave plate in the optical path, the light passes through the curved polarization selective reflector 664 during the second pass after being reflected from and collimated by the curved polarization selective reflector 664 and the plane reflector 660. Fig.6D The embodiments illustrated in also enable compact configuration in hybrid designs.

[0107] Fig. 7A is a schematic diagram illustrating a lensed optical fiber tip according to an embodiment of the present invention. Fig. 7A As shown in FIG. 7 , optical fiber 710 includes cladding 712 and core 714. The optical fiber can be considered as a point source of light emitting along an emission cone 716. Fig. 7A In the embodiment illustrated in , the point light source is illustrated as being recessed longitudinally within the core. A shallow lens surface 718 may be applied to the end of the optical fiber as illustrated. The lens surface 718 may be fabricated in a variety of different ways. As an example, a process utilizing focused ion beam (FIB) milling may be used to fabricate a low-stroke lens that provides aberration correction, such as in Fig. 7A In some embodiments, the lens surface 718 is formed directly on the optical fiber tip, however, in other embodiments, the mold is manufactured and the lens is formed separately from the optical fiber tip and then bonded to the optical fiber tip. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0108] The curvature of lens surface 718 may be selected to remove spherical aberrations arising from optical surfaces in the system, including those associated with Figure 2A 718 and the spherical aberration associated with the other surfaces. Thus, through the combination of aberration corrections provided by lens surface 718 and other surfaces, high image quality is provided by embodiments of the present invention. With a scanning fiber design as discussed herein, it is possible to perform optical correction on a per-pixel basis in addition to performing optical correction over a display wide scale.

[0109] Figure 7B is a schematic diagram illustrating a lensed fiber tip according to another embodiment of the present invention. In addition to aberration correction, such as by Figure 7B, embodiments of the present invention enable focusing of light emitted from an optical fiber tip. Lens 720 can be fabricated directly on the optical fiber tip (e.g., using a FIB milling process) or can be molded separately from the optical fiber tip and then bonded to the optical fiber tip. In this example, emission cone 722 is focused by lens 720 to form focusing cone 724. The strength of lens 720 can be such that the light is not focused, but the spread of light associated with emission cone 722 is reduced.

[0110] Figure 7C is a schematic diagram illustrating a lensed fiber tip according to an alternative embodiment of the present invention. In addition to aberration correction and focusing, as by Figure 7C , embodiments of the present invention enable defocusing of light emitted from a fiber tip, as illustrated by the use of a negative lens 730 illustrated in . Lens 730 can be fabricated directly on the fiber tip (e.g., using a FIB milling process) or can be molded separately from the fiber tip and then bonded to the fiber tip. In this example, emission cone 732 is defocused by lens 730 to form divergent cone 734. Thus, some embodiments enable numerical aperture to be increased via the use of a divergent lens on a fiber tip.

[0111] Compared to conventional optical systems (e.g. imaging an LCD into an image plane), which are constrained by Lagrangian invariants that maintain the optical invariants as constants throughout the system, fiber scanning systems can modify the characteristics of the pixels and change the spot size emitted by the fiber. Figure 7B and 7C With the lens illustrated in FIG. 1 , modification of the pixel size can be accomplished, for example, by increasing the numerical aperture, reducing the pixel size and reducing the imaging spot size, effectively reducing the mode field diameter.

[0112] For example, you can combine Figures 7A-7C The optical effects illustrated in the figure can be used to provide a lens tip that corrects for spherical aberration and focuses emitted light, corrects for spherical aberration and defocuses emitted light, corrects for spherical aberration while providing a lens having a convex region near the core and a concave region near the periphery of the optical fiber, etc. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0113] It should also be understood that the examples and embodiments described herein are for illustrative purposes only and various modifications or changes thereto will be suggested to those skilled in the art and are to be included within the spirit and purview of the present application and the scope of the appended claims.

Claims

1. A fiber scanning projector, comprising: Piezoelectric elements; a scanning optical fiber passing through and mechanically coupled to the piezoelectric element, wherein the scanning optical fiber is configured to emit light propagating along an optical path; a curved reflector disposed along and perpendicular to the optical path, wherein the curved reflector includes a hole and the scanning optical fiber passes through the hole; a planar polarization-sensitive reflector disposed along and perpendicular to the optical path; as well as A quarter wave plate is disposed adjacent to the curved reflector and the planar polarization-sensitive reflector.

2. The fiber scanning projector of claim 1, wherein the quarter wave plate is integrated with the planar polarization-sensitive reflector.

3. The fiber scanning projector of claim 1, wherein the curved reflector, the quarter wave plate, and the planar polarization-sensitive reflector are contained in a solid laminate component having optical power. 4 . The fiber scanning projector according to claim 1 , further comprising a lens disposed along the optical path and configured to adjust a working distance of the fiber scanning projector.

5. The fiber scanning projector of claim 4, wherein the planar polarization-sensitive reflector and the lens are separated by the working distance.

6. The fiber scanning projector of claim 4, further comprising a field of view amplifier disposed between the planar polarization sensitive reflector and the lens.

7. The fiber scanning projector of claim 4, further comprising a spherical aberration corrector disposed between the planar polarization-sensitive reflector and the lens.

8. The fiber scanning projector of claim 1, wherein the quarter wave plate and the curved reflector are separated by an air gap.

9. The fiber scanning projector of claim 1, wherein an output surface of the scanning optical fiber defines a spherical object surface.

10. A method of generating light by a fiber scanning projector, the method comprising: directing light along an optical path, wherein the light is generated by a scanning optical fiber mechanically coupled to a piezoelectric element and passes through a reflector including an aperture; passing the light through a quarter wave plate during a first pass; reflecting the light off a polarization-sensitive reflector disposed along the optical path; passing the light through the quarter wave plate during a second pass; reflecting the light off the reflector; passing the light through the quarter wave plate during a third pass; as well as The light is passed through the polarization-sensitive reflector.

11. The method according to claim 10, wherein: The reflector is planar and the polarization-sensitive reflector is curved.

12. The method according to claim 10, wherein: The reflector is curved and the polarization-sensitive reflector is planar.

13. The method of claim 10, wherein the quarter wave plate is integrated with the polarization-sensitive reflector.

14. The method of claim 10, wherein the reflector, the quarter wave plate, and the polarization-sensitive reflector are contained in a solid laminate component.

15. The method of claim 14, wherein the solid laminate component has optical power.

16. A fiber scanning projector, comprising: Piezoelectric elements; a scanning optical fiber passing through and mechanically coupled to the piezoelectric element, wherein the scanning optical fiber is configured to emit light propagating along an optical path; a planar reflector disposed along and perpendicular to the optical path, wherein the planar reflector comprises a hole and the scanning optical fiber passes through the hole; a curved polarization-sensitive reflector disposed along and perpendicular to the optical path; as well as A quarter wave plate is disposed between the planar reflector and the curved polarization-sensitive reflector.

17. The fiber scanning projector of claim 16, wherein the quarter wave plate is integrated with the bent polarization sensitive reflector.

18. The fiber scanning projector of claim 16, wherein the planar reflector, the quarter wave plate, and the curved polarization-sensitive reflector are contained in a solid laminate component having optical power.

19. The fiber scanning projector of claim 16, wherein the quarter wave plate and the bent polarization-sensitive reflector are separated by an air gap.

20. The fiber scanning projector of claim 16, wherein an output surface of the scanning optical fiber defines a spherical object surface.

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