Independent conjugate image generation

Abstract

The optical system may include (a) a light-directing optical element (LOE), the light-directing optical element (LOE) being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having a combining output arrangement for combining and outputting the image toward an eye of a user, the LOE having an combining input arrangement, and (b) an image projector, the image projector comprising an image generator for generating an image, and an image conjugate generator for generating a conjugate image, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction other than directly in front of the LOE.

Description

[Technical field]

[0001] The present invention relates to optical systems, and more particularly to optical systems for displaying images to a user. [Background technology]

[0002] Various types of displays, particularly near-eye displays (NEDs), typically employ one or more waveguides into which an image is incident from an image projector such that the image propagates by total internal reflection (TIR) ​​and then coupled out towards the observer's eye via one or more coupling-out elements (e.g., partially reflective inner surfaces ("facets"), diffraction gratings, etc.). Such waveguides are made of a transparent substrate having a pair of parallel outer major surfaces that extend along the length of the waveguide between which the image and its conjugate image are reflected. The image is preferably a collimated image, and the waveguide is preferably planar. For best performance, both the image and its conjugate image should completely fill the waveguide, such that illumination corresponding to each pixel of the image and each pixel of the conjugate image is present at every point within the thickness of the waveguide (relative to the area of ​​the waveguide that contributes to the output image that can reach the user's eye).

[0003] Filling of the waveguide can be accomplished by providing a coupling-in prism with a coupling-in surface oriented nearly perpendicular to the principal ray of the incident image, thereby allowing the image to land on an extended area of ​​one surface of the waveguide to generate a conjugate image. However, particularly in implementations where the image is incident at a relatively shallow angle to the principal exterior surface (i.e., close to 90 degrees to the surface normal), it is important to add to the dimensions of the waveguide the length of the coupling-in area required to fill the waveguide with the conjugate image. This is illustrated in FIG. 2A, which shows a typical coupling input to a waveguide 10. A coupling-in prism 14 cut from or attached to the waveguide substrate is used to direct the rays 40, 41 into the waveguide at a shallow angle. As the rays 40, 41 propagate through the waveguide, the ray 41 is reflected off the top surface of the waveguide, thereby becoming a conjugate of the ray 40. As is evident from FIG. 2A, even with a coupling input prism, a relatively large input aperture (and therefore a larger projector) is required to produce shallow beam conjugates in the waveguide.

[0004] An alternative approach to filling the waveguide, shown in Figure 2B, employs a 50% beam splitter (or "mixer") 13 inside the waveguide 10 near the midpoint that subdivides the thickness of the waveguide 10 between the major exterior surfaces and extends at least partially along the length of the waveguide parallel to the exterior surfaces. The beam splitter 13 is effective to partially reflect a ray to create its conjugate (e.g., ray 41) within the waveguide 10, allowing the input aperture and wedge prism 14 to be smaller (when compared to Figure 2A).

[0005] The presence of the mixer 13 allows the use of smaller projector apertures and coupling prisms, but importantly the mixer itself adds to the dimensions of the waveguide. The minimum length required for the mixer 13 is given by the formula l min= ω tan Φ, where ω is the width of the waveguide and Φ is the line of sight propagation (relative to the normal to the LOE major faces). Thus, the above constraint on the minimum length of the mixer requires the waveguide to be longer to accommodate the mixer. Furthermore, incorporating the mixer within the waveguide requires greater precision in creating the waveguide due to the required parallelism with the waveguide surface. Summary of the Invention

[0006] In accordance with the teachings of an embodiment of the present invention, an optical system is provided that includes: (a) a light-directing optical element (LOE), the light-directing optical element (LOE) being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having a combining output arrangement for combining and outputting the image toward an eye of a user, the LOE having an combining input arrangement; and (b) an image projector, the image projector including an image generator for generating an image and an image conjugate generator for generating a conjugate image, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE 10.

[0007] In accordance with the teachings of another embodiment of the present invention, there is provided an optical system for directing an image towards a user for viewing, the optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of the image by internal reflection at the first and second outer major surfaces, the LOE having a combining output arrangement for combining and outputting the image towards an eye of the user, the LOE having a combining input arrangement; and (b) an image projector comprising an image generator configured to sequentially generate an image and a conjugate image of the image, the image projector being coupled to the combining input opening to introduce the image and its conjugate image to the combining input opening before the image and its conjugate image impinge on either of the at least first and second outer major surfaces, the image generator being arranged to project the image and its conjugate image from a direction other than directly in front of the LOE.

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, depict various example systems, methods, etc. illustrating various example embodiments of aspects of the present invention. It will be understood that the boundaries of elements depicted in the figures (e.g., boxes, groups of boxes, or other shapes) represent one example of boundaries. Those skilled in the art will understand that one element may be designed as multiple elements, or multiple elements may be designed as one element. An element shown as an internal component of another element may be implemented as an external component, and vice versa. Additionally, elements may not be drawn to scale. [Brief description of the drawings]

[0009] [Figure 1A] 1 is a schematic isometric view of an optical system implemented using a light-directing optical element (LOE), constructed and operative in accordance with the teachings of the present invention, showing a top-down configuration; [Figure 1B]1 is a schematic isometric view of an optical system implemented using a light-directing optical element (LOE), constructed and operative in accordance with the teachings of the present invention, showing a side-entry configuration; [Figure 2A] FIG. 1 is a schematic side view showing a conventional coupling input of an image into a LOE via a coupling prism (described above). [Figure 2B] FIG. 1 is a schematic side view showing a conventional coupling input of an image to a LOE with an integrated beam multiplier (described above). [Diagram 3] FIG. 1C is a schematic side view of a portion of the optical system of FIGS. 1A and 1B showing the combined input of an image-conjugate image pair to a LOE. [Figure 4A] A one-dimensional LOE with only two reflecting surfaces is shown. [Figure 4B] A one-dimensional LOE with only two reflecting surfaces is shown. [Figure 5A] A two-dimensional LOE having four reflecting surfaces is shown. [Figure 5B] A two-dimensional LOE having four reflecting surfaces is shown. [Figure 6] A two-dimensional LOE with four reflecting surfaces in a hybrid configuration is shown. [Figure 7] 1 illustrates an exemplary optical system including a reflective surface forming a portion of the LOE to function as a coupling input arrangement. [Figure 8] 1 illustrates an exemplary optical system including a reflective surface disposed adjacent to the LOE to serve as a coupling input arrangement. [Figure 9] 1 illustrates an exemplary optical system that includes a pivoted reflective surface to function as a coupling input arrangement that sequentially varies a coupled input image. [Figure 10] An embodiment incorporating two polarizing beam splitters is shown. [Figure 11] FIG. 1 shows a schematic diagram of a technique for super-resolution or corrective resolution. [Figure 12A] 1 illustrates an embodiment in which the image generators are not part of the same matrix, but instead the matrix is ​​divided into multiple matrices. [Figure 12B]1 illustrates an embodiment in which the image generators are not part of the same matrix, but instead the matrix is ​​divided into multiple matrices. [Figure 12C] 1 illustrates an embodiment in which the image generators are not part of the same matrix, but instead the matrix is ​​divided into multiple matrices. [Figure 13A] 1 shows an embodiment in which a single matrix 114 is multiplexed in time to generate sequential images and conjugate images. [Figure 13B] 1 shows an embodiment in which a single matrix 114 is multiplexed in time to generate an image and a conjugate image sequentially. [Figure 13C] 1 shows an embodiment in which a single matrix 114 is multiplexed in time to generate sequential images and conjugate images. [Figure 14A] 13A-13C, but shows an embodiment in which the PBS is split in two. [Figure 14B] 13A-13C, but shows an embodiment in which the PBS is split in two. [Figure 14C] 13A-13C, but shows an embodiment in which the PBS is split in two. [Figure 15] 1 shows an embodiment utilizing a scanning laser across an LCOS matrix. [Figure 16A] 13 illustrates an embodiment in which the image and its conjugate image are angularly separated from each other and includes an angle-selective mirror disposed in front of the aperture. [Figure 16B] 13 illustrates an embodiment in which the image and its conjugate image are angularly separated from each other and includes an angle-selective mirror disposed in front of the aperture. [Figure 16C] 13 illustrates an embodiment in which the image and its conjugate image are angularly separated from each other and includes an angle-selective mirror disposed in front of the aperture. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Certain embodiments of the present invention provide an optical system including a light directing optical element (LOE) to achieve optical aperture expansion for the purposes of a head-up display, most preferably a near-eye display, which may be a virtual reality display, or more preferably an augmented reality display.

[0011] An exemplary implementation of a device in the form of a near-eye display employing a LOE 10 and in accordance with the teachings of one embodiment of the present invention, generally designated 100, is shown generally in Figures 1A and 1B. The near-eye display 100 employs a compact image projector (or "POD") 114 optically coupled to inject an image into the LOE (interchangeably referred to as a "waveguide," "substrate," or "slab") 10, where image light is captured by internal reflection at a set of mutually parallel planar exterior surfaces in one dimension.

[0012] The optical aperture expansion is achieved within LOE 10 by one or more arrangements for continuously redirecting the image illumination, typically employing a set of partially reflective surfaces (interchangeably referred to as "facets") parallel to one another and angled obliquely to the propagation direction of the image light, with each successive facet deflecting a portion of the image light in a deflected direction. To expand the aperture in one dimension, the facets also couple out the image light toward the user's eye. In some cases, as shown here, a two-dimensional aperture expansion is achieved by employing a first set of facets in region 116 to continuously redirect the image illumination captured / guided by internal reflection back into the LOE. The deflected image illumination then enters a second substrate region 118, which may be implemented as an adjacent separate substrate or as an extension of a single substrate, in which an out-coupling arrangement (e.g., a further set of partially reflective facets) progressively out-couples a proportion of the image illumination towards an observer's eye located within a region defined as the ocular movement box (EMB), thereby achieving a second dimension of optical aperture expansion. A similar function may be obtained using a diffractive optical element (DOE) to redirect and / or couple out the image illumination within one or both of regions 116 and 118.

[0013] The entire device may be implemented separately for each eye, and is preferably supported against the user's head, with each LOE 10 facing the user's corresponding eye. In one particularly preferred option as shown here, the support structure is implemented as an eyeglass frame having sides 120 for supporting the device against the user's ears. Other forms of support structure may also be used, including, but not limited to, a headband, a sun visor, or a device suspended from a helmet.

[0014] In the drawings and claims, reference is made herein to an X-axis extending horizontally (FIG. 1A) or vertically (FIG. 1B) in the general direction of extension of the first region of the LOE, and a Y-axis extending perpendicular thereto, i.e. vertically in FIG. 1A and horizontally in FIG. 1B. Very roughly speaking, the first LOE, or first region 116 of LOE 10, may be considered to achieve an aperture expansion in the X-direction, while the second LOE, or second region 118 of LOE 10, achieves an aperture expansion in the Y-direction. Details of the angular spread through which different parts of the field of view propagate will be explained more precisely below. It should be noted that an orientation as shown in FIG. 1A may be considered a "top-down" implementation, where the image illumination entering the main part (second region) of the LOE enters from the top edge, and the orientation shown in FIG. 1B may be considered a "side-entry" implementation, where the axis, referred to here as the Y-axis, is horizontally deployed. In the remaining figures, various features of certain embodiments of the invention are shown in the context of a "top-down" orientation similar to FIG. 1A. However, it should be understood that all of these features are equally applicable to side-entry implementations, which are also within the scope of the invention. In certain cases, other intermediate orientations are also applicable and, unless expressly excluded, are included within the scope of the invention. The two-dimensional magnification embodiments shown herein are merely exemplary, although the invention is also applicable to embodiments in which only a single dimension of aperture magnification is performed by the LOE.

[0015] It will be appreciated that the near-eye display 100 includes various additional components, including a controller 122 for operating the image projector 114, typically employing power from a small on-board battery (not shown) or some other suitable power source. It will be appreciated that the controller 122 includes all the necessary electronic components, such as at least one processor or processing circuitry, for driving the image projector.

[0016] One aspect of the invention relates to an implementation of an image projector 114 that includes an image conjugate generator arranged such that the image projector projects both a collimated image and its conjugate image into the LOE 10. Various non-limiting examples of image conjugate generators are illustrated herein below with reference to Figures 3-16. Accordingly, with reference to Figure 3, there is shown an enlarged schematic partial view of the optical system of Figure 1 for directing an image towards a user for viewing. The optical system includes LOE 10, which is formed from a transparent material and has first and second outer major surfaces 11a and 11b that are parallel to each other for supporting propagation of the image by internal reflection at those surfaces. LOE 10 also has a coupling output arrangement (as described above and in region 118 of Figure 1, not shown here) for coupling out the image towards the user's eye, and a coupling input aperture 15, shown in this case as a side edge of LOE 10.

[0017] Instead of relying on structures integrated with LOE 10 to generate the image conjugate pair, image projector 114 according to this aspect of the invention includes an image conjugate generator that generates the image conjugate pair before either the collimated image or the conjugate image strikes either of LOE 10's outer major surfaces 11a and 11b.

[0018] 3, image projector 114 includes an image generator 32 for generating an image, collimating optics 31 for collimating the image, and an image conjugate generator (here implemented as a second image generator 33 that generates a conjugate image). In the example shown, image generators 32 and 33 share a common collimating optics 31. Image projector 114 is coupled to coupling input aperture 15 to introduce the collimated image and its conjugate image directly into LOE 10 before the collimated image or its conjugate image impinges on either of the major outer surfaces IIa and 11b of LOE 10.

[0019] It will be appreciated that this solution contrasts sharply with the coupling input arrangement of Figures 2A and 2B, in which a conjugate image is generated within the LOE itself by reflection from the main outer surfaces (or from surfaces of the coupling prism that are contiguous with these surfaces and are defined for this purpose herein as being part of the main outer surfaces of the LOE).

[0020] The two image generators 32 and 33 are driven to generate the same image, one inverted, so that each field is shown identically from both fields. During assembly of the device, active alignment is preferably used, by mechanical adjustment or, more preferably, by digital correction of the image display position, to move the two images on the image generators so that they are aligned as complementary conjugate images in the LOE. Thus, the LOE is "filled" with both the main image and its conjugate image from the combined input aperture across the entire LOE, without requiring expansion of the LOE to achieve such filling.

[0021] In previous disclosures, the "image conjugate generator" is implemented as at least one reflective surface discontinuous with the main outer surface to generate a conjugate image. Instead, the term image generator in the context of this disclosure refers to any type of microdisplay image generator known in the art. Suitable examples include, but are not limited to, spatial light modulators (SLMs), including transmissive SLMs such as LCD displays, reflective SLMs such as LCOS displays, and active emissive displays such as OLED displays. Also, a scanning image generator, in which a fast scanning laser beam is modulated synchronously with its scanning motion, may be used as an image generator according to the present invention. In such a system, the optical arrangement shown in FIG. 3 is arranged such that a single scanning mirror is located on a plane that is optically imaged to plane 15. The image plane may also include a microlens array for beam expansion and / or an image modulator (LCOS) for further image resolution enhancement. This disclosure does not consider embodiments that include only one image generator in conjunction with at least one reflective surface that reflects the image projected by the one image generator to produce a conjugate image, to include an image conjugate generator. Instead, this disclosure discloses various embodiments including: (1) at least two image generators; (2) two images generated sequentially by the same generator; or (3) a single matrix generating two images simultaneously.

[0022] For example, Figures 4A and 4B show a one-dimensional (i.e., one-axis extended) LOE 10 having only two reflective surfaces 11a and 11b. The embodiment of Figure 4A uses a reflective surface 29 (e.g., the lower surface of prism 14) to generate a conjugate image. The image generator generates a light beam that is split into two substantially parallel beams. The first beam enters LOE 10 through aperture 15. The second light beam is reflected by reflective surface 29 to generate a conjugate light beam that enters LOE 10 with the first light beam through aperture 15. In effect, reflective surface 29 creates two conjugate apertures 15a, 15b through which the first beam and the conjugate beam can enter LOE 10, respectively. The first beam and the conjugate beam can then propagate at precisely opposite angles as they are reflected by surfaces 11a and 11b until a facet reflects the beam to the user's eye. The embodiment of Figure 4B, on the other hand, includes a second image generator 33 for generating the conjugate image. The image projector 114 includes an image generator 32 that generates a light beam and a second image generator 33 that generates a conjugate light beam. The first beam from the image generator 32 enters the LOE 10 through the aperture 15. The second conjugate light beam from the conjugate generator 33 enters the LOE 10 with the first light beam through the aperture 15. The first beam and the conjugate beam may then propagate at exactly opposite angles while being reflected by the surfaces 11a and 11b until the facets reflect the beam to the user's eye. In this way, the reflector 29 is not required, potentially reducing the size and complexity of the optical system. It is also possible to use a single image generating matrix 114, where 32 and 33 are images generated side by side within this one matrix. These images are generated as mirror images of each other (schematically illustrated by the thick arrows).

[0023] In another example, FIGS. 5A and 5B show a two-dimensional LOE 10 (vortex light-guiding optical element (VLOE)) having four reflective surfaces 11a-11d, as disclosed in U.S. patent application Ser. No. 16 / 172,897 and published as U.S. Pat. No. 10,564,417. A VLOE is a multi-dimensional (i.e., multi-axis extended) light-guiding optical element.

[0024] The embodiment of FIG. 5A uses two reflective surfaces 27, 29 (e.g., two reflective surfaces of a prism) to generate a conjugate image. The image generator generates a light beam that is effectively split into four beams. The first beam enters the VLOE 10 through the aperture 15. The second light beam is reflected by the reflective surface 27 to generate a conjugate light beam that enters the VLOE 10 with the first light beam through the aperture 15. The third light beam is reflected by the reflective surface 29 to generate a conjugate light beam that enters the VLOE 10 with the first and second light beams through the aperture 15. The fourth light beam is reflected by both reflective surfaces 27, 29 to generate a conjugate light beam that enters the VLOE 10 with the first, second, and third light beams through the aperture 15. In effect, the reflective surfaces 27, 29 generate four conjugate apertures 15a-15d through which the first beam and the conjugate beam can enter the VLOE 10. The four beams may then propagate at precisely opposite angles as they are reflected by surfaces 11a-11d until a facet reflects the beam away from VLOE 10. Again, 114 may be a single matrix with images of 32 and 33 within this matrix.

[0025] However, the embodiment of FIG. 5B includes second, third, and fourth image generators 33, 34, 35 to generate conjugate images. Image projector 114 includes image generator 32 generating a light beam, second image generator 33 generating a conjugate light beam, third image generator 34 generating another conjugate light beam, and fourth image generator 35 generating yet another conjugate light beam. A first beam from image generator 32 enters VLOE 10 through aperture 15. Conjugate light beams from conjugate generators 33, 34, 35 enter VLOE 10 with the first light beam through aperture 15. The first beam and the conjugate beam may then propagate at precisely opposite angles while being reflected by surfaces 11a-11d until a facet reflects the beam off VLOE 10. In this way, reflectors 27, 29 are not required, potentially reducing the size and complexity of the optical system.

[0026] Thus, the term image generator in the context of this disclosure refers to any type of microdisplay image generator known in the art. While previous disclosures may use at least one reflective surface that is discontinuous with the main exterior surface to generate the conjugate image, this disclosure instead discloses various embodiments that include at least two image generators 32, 33 as defined herein, a first image generator for generating an image, and at least one additional generator for generating a conjugate image. The exact placement and magnification of the image and the conjugate image are electronically calibrated when the optical placement is tested. Thus, high precision of the optical placement is not required.

[0027] In one embodiment, image generators 32, 33, etc. may project the image and the conjugate image with different polarizations (e.g., by using different waveplates in each matrix), thereby generating a mixture of polarizations within LOE 10. Such a mixture of polarizations within LOE 10 may be used to facilitate depolarization to counter polarization that may be introduced by optical elements within LOE 10. Depolarization may also be achieved by introducing at least one active or passive depolarizer into the optical system.

[0028] Such an embodiment including at least two image generators 32, 33 may be further combined with a reflecting surface. For example, FIG. 6 shows a hybrid embodiment using both a reflecting surface 29 and a second image generator 33 to generate a conjugate image. FIG. 6 shows a two-dimensional VLOE 10 having four reflecting surfaces 11a-11d. The projector 114 employs separate generators 32, 33 to generate a light beam and its conjugate light beam. The first beam and its conjugate light beam 32, 33 enter the VLOE 10 through an aperture 15. The first beam and its conjugate light beam are reflected by the reflecting surface 29 to generate a conjugate light beam that enters the VLOE 10 through the aperture 15. In effect, the reflecting surface 29 generates two apertures, i.e., aperture 15a through which the generated first beam and conjugate beam can enter the VLOE 10, respectively, and aperture 15b through which the reflected conjugate beam can enter the VLOE 10. The first beam and the conjugate beam may then propagate at exactly opposite angles while being reflected by surfaces 11a-11d until a facet reflects the beam off of VLOE 10. Image combining into VLOE 10 may therefore be achieved by a hybrid combination of optical and digital image multiplication, as shown in FIG. 6. The appropriate approach depends on the angle of the images propagating within LOE 10. Generally, but not always, for steeper angles, image optical (i.e., reflected) multiplication may be preferred, while for shallower propagating images, digital (i.e., second image generator) multiplication may be preferred.

[0029] Returning to FIG. 3, the two image generators 32, 33 show projected images from a direction directly in front of the LOE 10. That is, the two image generators 32, 33 are arranged symmetrically with respect to one another with respect to the central longitudinal axis α of the LOE 10, and are arranged on a plane π perpendicular to the major outer surfaces 11a and 11b. However, this topology (projecting images from a direction directly in front of the LOE 10) may not be ideal for many near-eye display applications. Instead, this disclosure discloses embodiments in which the image generators are arranged to project images from directions other than directly in front of the LOE 10. FIGS. 7-15 show examples of such embodiments.

[0030] FIG. 7 illustrates an embodiment in which a primary image and its conjugate image are coupled into the LOE 10 using a reflective surface 25 in the LOE 10 (i.e., side coupling). Light from the source 20 (e.g., laser scanner, LED, etc.) is collected by optics 22 (e.g., lens, light guide, etc.) and illuminates the image generator 32 and conjugates the conjugate image generator 33 (e.g., LCOS, DLP, etc.). In some embodiments, the image generators 32, 33 (e.g., LCOS, LCD, etc.) may generate their own illumination (e.g., OLED, micro LED, etc.) without the source 20 or optics 22. The generators 32, 33 may also correspond to a scanning mirror and microlens array (MLA) if the light source is a collimated laser. In the illustrated embodiment, the light from the source generators 32, 33 is collimated by collimating optics 31 and injected into the LOE 10.

[0031] Thus, the example of FIG. 7 includes an image generator 32 for generating an image, an image conjugate generator 33 for generating a conjugate image, and a collimating optic 31 for collimating the image. In the example shown, the image generators 32 and 33 share a common collimating optic 31. Light from the image generators 32, 33 is coupled into the LOE 10 to introduce the collimated image and its conjugate image directly into the LOE 10 before it hits either of the major outer surfaces 11a and 11b. The first beam and the conjugate beam may then propagate at exactly opposite angles while being reflected by the surfaces 11a-11b until the facet 56 reflects the beam out of the LOE 10. This LOE 10 has a reflecting surface 25 built therein, which has a dielectric or metallic coating. The entrance pupil of this configuration is defined by the reflecting surface 25. In this configuration, the spacing between optics 31 and top surface 11a of LOE 10 is set to maintain reflectivity within LOE 10. Reflectivity within LOE 10 may be achieved by total internal reflection or a coating. As can be easily seen from FIG. 7, image generators 32, 33 are positioned to project images from the side of LOE 10, rather than from a direction directly in front of LOE 10.

[0032] FIG. 8 shows a similar implementation to FIG. 7, but utilizes mirror 44 to couple the primary image and its conjugate image into LOE 10. Light from source 20 is collected by optics 22 and illuminates image generator 32 and conjugate image generator 33. In some embodiments, image generators 32, 33 may generate their own illumination without source 20 or optics 22. Light from source generators 32, 33 is collimated by collimating optics 31, and mirror 44 reflects the light incident on LOE 10 through aperture 15. Mirror 44 is set at an appropriate angle to introduce the primary and conjugate images into LOE 10 before they hit either of major exterior surfaces 11a and 11b. The collimated and conjugate beams may then propagate at precisely opposite angles as they are reflected by surfaces 11a-11b until facet 56 reflects the beams off LOE 10. As can be easily understood from FIG. 8, image generators 32, 33 are arranged to project images from the side of LOE 10, rather than from directly in front of it.

[0033] Figure 9 shows an implementation similar to that of Figures 7 and 8, but utilizing a tilted mirror 44 on a pivot 45. The mirror 44 can be made to pivot between two angles at an appropriate rate (e.g., 30 times per second, 60 times per second, 120 times per second, etc.) in coordination with the image generators 32, 33, thereby allowing for continuous combined input of the light beams from the image generators 32, 33. This approach allows for a significant reduction in the size of the optical system 31, which must transmit only one of the image or the conjugate image at any one time.

[0034] Image generator 32 generates an image in cooperation with pivoting mirror 44, which is set at the proper angle to insert the image through aperture 15. Light from image generator 32 is coupled into LOE 10 to introduce the collimated image into LOE 10 before it strikes either of major exterior surfaces 11a and 11b. Pivoting mirror 44 is then pivoted to the proper angle to insert the conjugate image through aperture 15. Image generator 33 generates a conjugate image in cooperation with pivoting mirror 44, which is set at the proper angle to insert the conjugate image through aperture 15. Light from image generator 33 is coupled into LOE 10 to introduce the conjugate image into LOE 10 before it strikes either of major exterior surfaces 11a and 11b. The collimated image and conjugate beams may then propagate at precisely opposite angles as they are reflected by surfaces 11a-11b until facet 56 reflects the beam away from LOE 10. If the pivoting mirror 44 is pivoted at a sufficiently high speed, the viewer will perceive the resulting image output by the facet 56 as being similar to that output by the systems of FIGS.

[0035] In alternative embodiments, the illustrated concept can be used to generate four or more conjugate images that are injected into LOE 10. Image generator 32 may generate images in cooperation with pivoting mirror 44, which is set at the appropriate angle to insert the image through aperture 15. Light from image generator 32 is coupled into LOE 10 to introduce a collimated image into LOE 10 before the collimated image strikes either of major exterior surfaces 11a and 11b. Pivoting mirror 44 is then pivoted to the appropriate angle to insert a first conjugate image through aperture 15. Image generator 33 generates a first conjugate image in cooperation with pivoting mirror 44, which is set at the appropriate angle to insert the first conjugate image through aperture 15. Light from image generator 33 is coupled into LOE 10 to introduce a first conjugate image into LOE 10 before the first conjugate image strikes either of major exterior surfaces 11a and 11b. The pivoting mirror 44 is then pivoted to the proper angle to insert the second conjugate image through the opening 15. The image generator 32 generates the second conjugate image in cooperation with the pivoting mirror 44 set at the proper angle to insert the second conjugate image through the opening 15. The light from the image generator 32 is coupled into the LOE 10 to introduce the second conjugate image into the LOE 10 before the second conjugate image strikes either of the major exterior surfaces 11a and 11b. The pivoting mirror 44 is then pivoted to the proper angle to insert the third conjugate image through the opening 15. The image generator 33 generates the third conjugate image in cooperation with the pivoting mirror 44 set at the proper angle to insert the third conjugate image through the opening 15. The light from the image generator 33 is coupled into the LOE 10 to introduce the third conjugate image into the LOE 10 before the third conjugate image strikes either of the major exterior surfaces 11a and 11b. The collimated image and the conjugate image may then propagate along LOE 10 (eg, a VLOE) until facet 56 reflects the beam off of LOE 10.

[0036] 9, image generators 32, 33 are arranged to project images from the side rather than from a direction directly in front of LOE 10. It may also be possible to use only one image generator 32 (and not 33), with the scanning mirror flipping between the two orientations and the image generator flipping between the two mirror images.

[0037] FIG. 10 shows an implementation utilizing a polarizing beam splitter (PBS) (disclosed as U.S. Patent Application Serial No. 12 / 092,818 and published as U.S. Patent No. 9,551,880). In the embodiment of FIG. 10, two adjacent PBSs 51, 53 are used. The first PBS 51 is disposed between the light source 20 (e.g., an LED or a scanning laser mirror), the refocusing reflective lens 55, and the image generating matrix 114. The second PBS 53 is disposed between the matrix 114 and the collimating reflective lens 57. Here, the matrix 114 generates multiple images (a primary image and one or more conjugate images), similar to the embodiment of FIG. 5B. In the diagram of FIG. 10, only two image generators 32, 33 may be shown, but additional image generators may be disposed along the intra-page axis.

[0038] In practice, p-polarized light from source 20 is transmitted through PBS 51 and hits refocusing reflecting lens 55, which reflects and transforms the incident beam. The reflected beam, now s-polarized, reflects off PBS 51 and PBS 53 to illuminate image generator matrix 32 and conjugate image generator matrix 33. In some embodiments, image generator matrices 32, 33 may generate their own illumination without source 20. Light from source generator matrices 32, 33, now p-polarized, is transmitted through PBS 53 and collimated and reflected by collimating reflecting lens 57. Finally, the reflected beam, now s-polarized, reflects off PBS 53 and enters LOE 10 through aperture 15. The collimated and conjugate beams may then propagate at precisely opposite angles, being reflected by surfaces along LOE 10 until facet 56 reflects the beam off LOE 10. As can be easily understood from FIG. 10, image generators 32, 33 are arranged to project images from the side of LOE 10, rather than directly in front of it.

[0039] FIG. 11 shows a schematic illustration of an image processing flow that may be used with some of the embodiments disclosed herein, particularly those utilizing a two-dimensional LOE 10 (VLOE). To minimize and / or offset the loss of resolution associated with the matrix 114 that segments the high-resolution original image 30 into sub-images 32, 33, 34, 35, etc., all sub-images may be directly interpolated from the original high-resolution original image 30. There may be some overlap between the sub-images 32, 33, 34, 35, etc., as they together represent the image 30. As a result, sub-pixel resolution of the final image output by the facet 56 may be achieved as perceived by the observer when combining all the beams projected to the eye. This is, in this application, a form of super-resolution that minimizes and / or offsets the loss of resolution associated with segmenting the high-resolution original image 30 into sub-images 32, 33, 34, 35, etc.

[0040] Figures 12A-12C show another implementation of the technique of the present invention. Figures 12A-12C show an embodiment in which the image generators 32, 33 are not part of the same matrix 114, but instead the matrix 114 is divided into multiple matrices 114a and 114b. The image generator 32 forms part of the first matrix 114a and the conjugate image generator forms part of the second matrix 114b. The two matrices 114a, 114b are smaller than the single matrix 114 described in the previous embodiment. This reduction in size, and the flexibility of being able to position the first matrix 114a and the second matrix 114b independently of each other, creates important design advantages.

[0041] In Fig. 12A-C, the light corresponding to the first image generator 32 is indicated by a solid arrow, and the light corresponding to the conjugate image generator 33 is indicated by a dashed arrow. In the configuration of Fig. 12A-C, the optical prisms 114a and 114b and the LCOS matrices 32, 33 are tilted, as are the collimating reflecting lenses 57 and 58. This tilt allows the illustrated embodiment to contain all the beams in a small optical arrangement while still maintaining high quality, since all the beams interact with the optics 57, 58 and the prisms 114a, 114b almost perpendicularly. Two adjacent PBSs 51, 53 are used. The first PBS 51 is disposed between the light source 20 (e.g., LED or scanning laser mirror) and the image generating prisms 114a, 114b. The second PBS 53 is disposed between the prisms 114a, 114b and the collimating reflecting lenses 57, 58.

[0042] FIG. 12B shows a ray chart associated with image generator 32 (main image), and FIG. 12C shows a ray chart associated with conjugate image generator 33 (conjugate image). In practice, p-polarized light from light source 20 is transmitted through PBS 51 to matrix 114a and illuminates image generator 32. The image generated by image generator 32 is s-polarized and therefore reflects off PBS 51 and PBS 53 to collimating reflecting lens 57. The collimated light reflected from lens 57, now p-polarized, is transmitted through PBS 53 and enters LOE 10 through aperture 15 (only a portion of LOE 10 is shown). At the same time, s-polarized light from light source 20 is reflected off PBS 51 to matrix 114b and illuminates conjugate image generator 33. The image generated by conjugate image generator 33 is p-polarized and therefore transmitted through PBS 51 and PBS 53 to collimating reflecting lens 58. The collimated light reflected from lens 58 , which is now s-polarized, reflects off of PBS 53 and enters LOE 10 through aperture 15 .

[0043] The collimated and conjugate beams may then propagate at precisely opposite angles as they are reflected by surfaces along LOE 10 until facet 56 reflects the beams off LOE 10. As can be readily seen from Figures 12A-12C, image generators 32, 33 are positioned to project images from the side of LOE 10 rather than from a direction directly in front of it.

[0044] 13A-13C show an embodiment of the invention in which a single matrix 114 is multiplexed in time to generate an image and a conjugate image sequentially. Two adjacent PBSs 51, 53 are used. The first PBS 51 is disposed between the light source 20 (e.g. LED or scanning laser mirror) and the image generating matrix 114, and between the image generating matrix 114 and the liquid crystal switch 60. The second PBS 53 is disposed between the liquid crystal switch 60 and the collimating reflective lenses 57, 58. In the configuration of FIGS. 13A-13C, the collimating reflective lenses 57 and 58 are tilted. This tilt allows the illustrated embodiment to contain all the beams in a small optical arrangement while still maintaining high quality, since all the beams interact with the optics 57, 58 and the matrix 114 almost perpendicularly.

[0045] FIG. 13B shows a ray chart associated with the image generator 32 / 33 that generates the main image, and FIG. 13C shows a ray chart associated with the conjugate image generator 32 / 33 that generates the conjugate image.

[0046] To transmit the primary image (FIGS. 13A and 13B), p-polarized light (large arrow) from light source 20 is transmitted through PBS 51 to matrix 114 to illuminate image generator 32. The primary image (solid arrow) generated by image generator 32 is s-polarized and is therefore reflected from PBS 51 towards switch 60. For the primary image, liquid crystal switch 60 maintains the polarization (s-polarized) and therefore the light (solid arrow) reflects from PBS 53 to collimating reflecting lens 57. The collimated light reflected from lens 57, now p-polarized, is transmitted through PBS 53 and enters LOE 10 via aperture 15. Then, to transmit the conjugate image (FIGS. 13A and 13C), p-polarized light (large arrow) from light source 20 is transmitted through PBS 51 to matrix 114 to illuminate image generator 33. The conjugate image (solid arrow) produced by image generator 33 is s-polarized and is therefore reflected off PBS 51 towards switch 60. For the conjugate image, liquid crystal switch 60 rotates the polarization of the light (now p-polarized) so that the light (dashed arrow) is transmitted through PBS 53 to collimating reflecting lens 58. The collimated light reflected from lens 58, now s-polarized (solid arrow), reflects off PBS 53 and into LOE 10 through aperture 15. By rapidly switching between the two configurations (switch 60 and the appropriate images on matrix 14), the illumination on LOE 10 is perceived as if it were simultaneously an image and a conjugate image.

[0047] The collimated and conjugate beams may then propagate at precisely opposite angles as they are reflected by surfaces along LOE 10 until facet 56 reflects the beams off LOE 10. As can be readily seen from Figures 13A-13C, image generators 32 / 33 are positioned to project an image from the side of LOE 10 rather than from a direction directly in front of it.

[0048] 14A-14C are equivalent to FIGS. 13A-13C, but show an embodiment in which the PBS 53 is split into two, 53a and 53b. The operation is identical to that of FIGS. 13A-13C described above, except that the main image beam is reflected by 53a and the conjugate image beam is reflected by 53b. As a result, the illumination on the matrix 114 for both alternatives is overlapped. According to this embodiment, it is possible to implement the split PBS 53a, 53b in a two-matrix configuration 114a and 114b (see FIGS. 12A-12C), thereby achieving the same illumination orientation for the main and conjugate images, thereby improving the illumination coupling efficiency.

[0049] As can be easily understood from FIGS. 14A to 14C, image generators 32 / 33 are disposed so as to project images from the side of LOE 10, rather than from a direction directly in front of LOE 10.

[0050] In all the above embodiments, other types of matrices may be used that do not require a PBS, such as LCD (direct through optical path) or DLP (non-PBS prism).

[0051] FIG. 15 shows an embodiment utilizing a scanning laser 10 over an LCOS matrix 114. Such a configuration can achieve high light coupling efficiency at high resolution (characterized by the large pixel count of the LCOS 114). In the embodiment shown, only the main image beam is shown for clarity. Two beams are generated by two lasers 70. These beams are focused by lens 22 through a mirror scanner 80 and reflected by a PBS 51 onto the matrix 114. The two beams generate two images on the matrix 114, which is modulated to further improve the image resolution. The two beams transmit through the PBS 51, are refocused by a reflecting lens 55, and are reflected by the PBS 51 onto a diffuser or microlens array (MLA) 44. The MLA 44 increases the divergence of each beam so that the beams fill the aperture 15 of the LOE 10. Collimating optics 31 collimate the beams before incidence on the LOE 10.

[0052] As shown, using two beams to generate the main and conjugate images has substantial advantages: 1) scanning speed is increased and minimal flicker perception is visible, and 2) the use of two beams reduces the actual aperture size, thereby reducing the need for a wide divergence MLA 44. In extreme cases (small aperture 15 or large initial beam), the MLA 44 may not be necessary.

[0053] 15 may be used when illuminating the LCOS 114 with LEDs. Additionally, this configuration may be used in conjunction with continuous single image generation, as described above.

[0054] Another solution for a system in which an image and its conjugate image are angularly separated from each other is shown in Figures 16A-16C. Figure 16A shows a ray chart including both the main image and the conjugate image. Figures 16B and 16C show ray charts showing the main image and the conjugate image separately. The system of Figures 16A-16C includes an angle-selective mirror 82 disposed in front of the aperture 15. The mirror 82 may have a coating designed to reflect image beams propagating at certain angles (e.g., shallow angles) while being transparent to beams propagating at other angles (e.g., steep angles). Such a coating was designed and shown in International Application No. PCT / IL2004 / 000813, published as WO 2005 / 024491, and International Application No. PCT / IL2015 / 051222, published as WO 2016 / 103251.

[0055] In operation, the image generator 32 (e.g., an SLM) generates a main image (FIG. 16B). The s-polarized image is reflected from the PBS 51 to the collimating reflecting lens 57. The collimated light reflected from the lens 57, which is now p-polarized, is transmitted through the PBS 51, through the angle-selective mirror 82 (because the angle is very steep and nearly vertical) to the mirror 44, which reflects the light back towards the angle-selective mirror 82. This time, the light reaches the angle-selective mirror 82 at a shallow angle and is therefore reflected towards the aperture 15. At the same time, the image generator 33 (e.g., an SLM) generates a conjugate image (FIG. 16C). The s-polarized image is reflected from the PBS 51 to the collimating reflecting lens 57. The collimated light reflected from the lens 57, which is now p-polarized, is transmitted through the PBS 51, through the angle-selective mirror 82 (because the angle is very steep and nearly vertical) to the aperture 15. At the same time, the image generator 33 generates a conjugate image (FIG. 16C). Thus, on the LCOS 114, the two images occupy adjacent sections, and the total area of ​​the LCOS 114 can be reduced.

[0056] definition The following includes definitions of selected terms used herein. The definitions include various examples or forms of components that fall within the scope of the terms and that may be used for implementation. The examples are not intended to be limiting. Both singular and plural forms of the terms are possible within the definitions.

[0057] An "operable connection," or a connection in which entities are "operably connected," is a connection in which signals, physical communications, or logical communications may be sent and received. Typically, an operable connection includes a physical interface, an electrical interface, or a data interface, but it should be noted that an operable connection may include different combinations of the above or other types of connections sufficient to enable operable control. For example, two entities may be operably connected by being able to communicate signals to each other directly or through one or more intermediate entities, such as a processor, operating system, logic, software, or other entity. Logical or physical communication channels may be used to create an operable connection.

[0058] To the extent that the term "includes" or "including" is used in the detailed description or claims, it is intended to be inclusive in a similar manner to the term "comprising" when interpreted as a transitional term in the claims. Furthermore, to the extent that the term "or" is used in the detailed description or claims (e.g., A or B), it is intended to mean "A or B or both." If the applicant intends to indicate "only A or B, but not both," the term "only A or B, but not both" is used. Thus, the use of the term "or" in this specification is inclusive and not exclusive. See: Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d.Ed.1995).

[0059] Although the exemplary systems, methods, etc. are illustrated by describing examples, and the examples are described in considerable detail, it is not the intention of the applicant to limit the scope to such details or in any way limit the scope. Of course, it is not possible to describe every conceivable combination of components or methodologies for purposes of describing the systems, methods, etc. described herein. Additional advantages and modifications will readily occur to those skilled in the art. Thus, the present invention is not limited to the specific details, representative apparatus, and illustrative examples shown and described. As such, the present application is intended to embrace changes, modifications, and variations that fall within the spirit and scope of the appended claims. Moreover, the foregoing description is not intended to limit the scope of the present invention. Rather, the scope of the present invention should be determined by the appended claims and their equivalents.

Claims

1. 1. An optical system for directing an image towards a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector separate from the LOE, the image projector comprising an image generator for generating an image and an image conjugate generator for generating a conjugate image of the image, the image projector being arranged with respect to the combining input aperture to project the image and the conjugate image from the projector and introduce the image and the conjugate image into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE; a coupling input reflector extending obliquely relative to the first and second outer major surfaces; a pivot operatively connected to the coupled input reflector and configured to sequentially pivot the coupled input reflector in coordination with the image generator and the image conjugate generator to generate the image and the conjugate image; An optical system comprising:

2. 2. The optical system of claim 1, wherein the coupling input reflector is deployed at an angle relative to the first and second outer major surfaces such that light from the image projector couples into the LOE from a side of the first outer major surface or a side of the second outer major surface.

3. The optical system of claim 1, wherein the image projector comprises the image generator, the conjugate image generator, and at least one reflective surface discontinuous with the main outer surface for generating one or more additional conjugate images.

4. An optical system as described in claim 1, wherein the image generator and the conjugate image generator are not part of a single matrix, but instead are arranged at different positions or orientations and project light in different directions.

5. An optical system as described in claim 1, wherein the image generator and the conjugate image generator correspond to first and second lasers in combination with a matrix.

6. An optical system as described in claim 1, wherein the image generator and the conjugate image generator are inclined or at an angle relative to each other.

7. An optical system as described in claim 6, comprising one or more collimating reflective lenses, wherein the image generator and the conjugate image generator are inclined or at an angle relative to each other and to the collimating reflective lenses.

8. An optical system for directing an image toward a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector separate from the LOE, the image projector comprising an image generator for generating an image and an image conjugate generator for generating a conjugate image of the image, the image projector being arranged with respect to the combining input aperture to project the image and the conjugate image from the projector and introduce the image and the conjugate image into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE; two or more adjacent polarizing beam splitters (PBSs), a first PBS and a second PBS; two or more refocusing reflective lenses operatively connected to the beam splitter; a light source disposed on a first side of the first PBS, the light source configured to emit a polarized beam of a first polarization such that the emitted polarized beam transmits through the first PBS and strikes the refocusing reflective lens, which reflects the incident beam and rotates the polarization of the incident beam such that the reflected beam reflects from the first PBS towards the second PBS, the reflected beam reflects from the second PBS to the image projector to illuminate the image generator and the conjugate image generator, the projected image and conjugate image transmit through the second PBS and strike a second refocusing reflective lens, which reflects the incident beam and rotates the polarization of the incident beam such that the reflected beam reflects from the second PBS to the LOE; An optical system comprising:

9. An optical system for directing an image toward a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector separate from the LOE, the image projector comprising an image generator for generating an image and an image conjugate generator for generating a conjugate image of the image, the image projector being arranged with respect to the combining input aperture to project the image and the conjugate image from the projector and introduce the image and the conjugate image into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE; Equipped with the image projector comprises the image generator and at least three conjugate image generators; An optical system, wherein the system interpolates a high resolution original image into lower resolution sub-images generated as the image and the conjugate image.

10. An optical system for directing an image toward a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector separate from the LOE, the image projector comprising an image generator for generating an image and an image conjugate generator for generating a conjugate image of the image, the image projector being arranged with respect to the combining input aperture to project the image and the conjugate image from the projector and introduce the image and the conjugate image into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE; an angle-selective mirror disposed in front of the coupling input arrangement and configured to reflect image beams propagating at a particular angle while being transparent to beams propagating at other angles; Equipped with an optical system wherein the image generator generates the image polarized with a first polarization to be reflected from a PBS to a collimating reflecting lens, through the angle-selective mirror, and to a mirror that reflects the image back to the angle-selective mirror to be reflected towards the combining input arrangement.

11. An optical system for directing an image toward a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector separate from the LOE, the image projector comprising an image generator for generating an image and an image conjugate generator for generating a conjugate image of the image, the image projector being arranged with respect to the combining input aperture to project the image and the conjugate image from the projector and introduce the image and the conjugate image into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator and the image conjugate generator being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE; Equipped with an optical system in which the image generator and the conjugate image generator correspond to first and second lasers in combination with a matrix, the first laser illuminating the image and the second laser illuminating the conjugate image, the image beam being focused by a lens, then reflected through a mirror scanner and onto the matrix by a PBS, from the matrix, again through the PBS, refocused by a reflective lens, and reflected by the PBS onto a diffuser or microlens array (MLA).

12. 1. An optical system for directing an image towards a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector distinct from the LOE, the image projector comprising an image generator configured to sequentially generate an image and a conjugate image of the image, the image projector coupled to the combining input aperture such that the image and the conjugate image are projected from the projector and introduced into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator arranged to project the image and the conjugate image from a direction other than directly in front of the LOE; a liquid crystal polarization switch configured to move in coordination with the image projector such that the switch does not rotate polarization when the image is being generated and rotates polarization when the conjugate image is being generated, or vice versa; An optical system comprising:

13. An optical system for directing an image toward a user for viewing, said optical system comprising: (a) a light-directing optical element (LOE), the LOE being formed from a transparent material and having at least first and second mutually parallel outer major surfaces for supporting propagation of an image by internal reflection at the first and second outer major surfaces, the LOE having an output coupling arrangement for coupling the image out toward an eye of the user, the LOE having an input coupling aperture; (b) an image projector distinct from the LOE, the image projector comprising an image generator configured to sequentially generate an image and a conjugate image of the image, the image projector coupled to the combining input aperture such that the image and the conjugate image are projected from the projector and introduced into the combining input aperture before the image and the conjugate image impinge on either of the at least first and second outer major surfaces, the image generator arranged to project the image and the conjugate image from a direction other than directly in front of the LOE; a coupling input reflector extending obliquely relative to the first and second outer major surfaces; a pivot operatively connected to the coupled input reflector and configured to sequentially pivot the coupled input reflector in coordination with the image generator and the image conjugate generator to generate the image and the conjugate image; An optical system comprising:

Images