CN117897646A - Independent conjugate image generation - Google Patents

Abstract

An optical system may include: (a) A light guiding optical element (LOE) formed of a transparent material and having at least a first and a second major outer surface parallel to each other for supporting propagation of an image by internal reflection at the first and second major outer surfaces, the LOE having a coupling-out arrangement for coupling out the image towards an eye of a user, the LOE having a coupling-in arrangement; and (b) an 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 not directly in front of the LOE.

Description

Independent conjugate image generation

Technical Field

The present invention relates to an optical system, and in particular to an optical system for displaying an image to a user.

Background

Various types of displays, and particularly near-eye displays (NED), typically employ one or more waveguides in which an image is injected from an image projector to propagate within the waveguide by total internal reflection (total internal reflection, TIR) and is subsequently coupled out towards the eye of the viewer 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 major outer surfaces extending along the length of the waveguide, between which the image and its conjugate are reflected. The image is preferably a collimated image and the waveguide is preferably planar. For optimal performance, both the image and its conjugate should completely fill the waveguide such that the illumination corresponding to each pixel of the image and each pixel of the conjugate image is present at each point within the thickness of the waveguide (for the area of the waveguide that contributes to the output image that can reach the user's eye).

Filling of the waveguide may be achieved by providing a coupling-in prism having a coupling-in surface oriented substantially perpendicular to the chief ray of the injected image, so that the image can fall on an extended area of one surface of the waveguide to generate a conjugate image. However, especially for embodiments in which the image is injected at a relatively shallow angle relative to the main outer surface (i.e. approximately 90 degrees from the normal of the surface), the length of the coupling-in region required for filling the waveguide with the conjugate image significantly increases the size of the waveguide. This is illustrated in fig. 2A, fig. 2A showing a typical coupling into the waveguide 10. The coupling-in prism 14 cut from or attached to the waveguide substrate serves to guide the light rays 40, 41 into the waveguide at shallow angles. As light rays 40, 41 propagate within the waveguide, light ray 41 reflects from the top surface of the waveguide, becoming the conjugate of light ray 40. As is evident from fig. 2A, even with the use of a coupling-in prism, a relatively large input aperture (and thus a large projector) is required to produce the conjugation of shallow light rays within the waveguide.

An alternative method for filling the waveguide shown in fig. 2B is to employ a 50% beam splitter (or "mixer") 13 at about the midpoint inside the waveguide 10, the beam splitter 13 subdividing the thickness of the waveguide between the major outer surfaces and extending at least a portion of the way along the length of the waveguide parallel to the outer surfaces. The beam splitter 13 effectively partially reflects the light to generate its conjugate (e.g., light 41) within the waveguide and allows for a smaller input aperture and wedge prism 14 (as compared to fig. 2A).

Although the presence of the mixer 13 allows the use of smaller projector apertures and coupling prisms, the mixer itself significantly increases the size of the waveguide. The minimum length required for the mixer 13 can be calculated by equation l _min =ω·tan (Φ), where ω is the width of the waveguide and Φ is the propagation of the angle of the field of view (relative to the normal to the main surface of the LOE). Thus, the above-described limitation on the minimum length of the mixer requires making the waveguide longer to accommodate the mixer. Furthermore, the inclusion of a mixer inside the waveguide requires a higher precision for producing the waveguide, since it needs to be parallel to the waveguide surface.

Disclosure of Invention

According to the teachings of embodiments of the present invention, there is provided an optical system that may include: (a) A light guiding optical element (LOE) formed of a transparent material and having at least a first and a second major outer surface parallel to each other for supporting propagation of an image by internal reflection at the first and second major outer surfaces, the LOE having a coupling-out arrangement for coupling out the image towards an eye of a user, the LOE having a coupling-in arrangement; and (b) an 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 not directly in front of the LOE.

According to the teachings of another embodiment of the present invention, there is provided an optical system for directing an image toward a user for viewing, the optical system comprising: (a) A light guiding optical element (LOE) formed of a transparent material and having at least a first and a second major outer surface parallel to each other for supporting propagation of an image by internal reflection at the first and second major outer surfaces, the LOE having a coupling-out arrangement for coupling out the image towards an eye of a user, the LOE having a coupling-in arrangement; (b) An image projector comprising an image generator configured to sequentially generate images and conjugate images of the images, the image projector being coupled to the coupling-in aperture to introduce the images and their conjugate images into the coupling-in aperture before the images and the conjugate images impinge on either of the at least first and second major outer surfaces, the image generator being arranged to project the images and the conjugate images from directions not directly in front of the LOE.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various example systems, methods, etc., which illustrate various example embodiments of aspects of the invention. It will be appreciated that the element boundaries (e.g., boxes, groups of boxes, or other shapes) shown in the figures represent one example of the boundaries. Those of ordinary skill in the art will understand that an element may be designed as multiple elements or that 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. Furthermore, elements may not be drawn to scale.

Drawings

FIGS. 1A and 1B are schematic isometric views of an optical system implemented using light-guide optical elements (LOEs) constructed and operative in accordance with the teachings of the present invention, showing a top-down injection configuration and a lateral injection configuration, respectively;

FIG. 2A is a schematic side view as described above showing conventional coupling of an image into an LOE via a coupling prism;

FIG. 2B is a schematic side view as described above showing conventional coupling of an image into an LOE with an integrated beam multiplier;

FIG. 3 is a schematic side view of a portion of the optical system of FIGS. 1A and 1B, showing the coupling of an image and a conjugate image pair into an LOE;

FIGS. 4A and 4B show a one-dimensional LOE with only two reflective surfaces;

FIGS. 5A and 5B illustrate a two-dimensional LOE with four reflective surfaces;

FIG. 6 shows a two-dimensional LOE with four reflective surfaces in a hybrid arrangement;

FIG. 7 illustrates an exemplary optical system including a reflective surface forming part of an LOE to serve as a coupling-in arrangement;

FIG. 8 illustrates an exemplary optical system including a reflective surface disposed adjacent to an LOE to serve as an in-coupling arrangement;

FIG. 9 illustrates an exemplary optical system including a pivoting reflective surface to serve as a coupling-in arrangement for sequentially changing a coupling-in image;

FIG. 10 illustrates an embodiment including two polarizing beamsplitters;

fig. 11 shows a schematic diagram of a technique for super resolution or improved resolution.

Fig. 12A to 12C show embodiments in which the image generator is not part of the same matrix but divides the matrix into several matrices.

Fig. 13A-13C illustrate an embodiment in which a single matrix 114 is multiplexed in time to sequentially generate images and conjugate images.

Fig. 14A-14C illustrate an embodiment equivalent to fig. 13A-13C but in which the PBS is split into two PBSs.

Fig. 15 shows an embodiment using a scanning laser on an LCOS matrix.

Fig. 16A to 16C show an embodiment in which the images and their conjugates are angularly separated from each other and include an angle-selective mirror disposed in front of the aperture.

Detailed Description

Certain embodiments of the present invention provide an optical system comprising a light guide optical element (LOE) for achieving an expansion of the optical aperture for the purpose of a heads-up display and most preferably a near-eye display, which may be a virtual reality display or more preferably an augmented reality display.

An exemplary implementation of a device in the form of a near-eye display, generally indicated by reference numeral 100, employing the teachings of an embodiment of the present invention of an LOE 10 is schematically illustrated in fig. 1A and 1B. The near-eye display 100 employs a compact image projector (or "POD") 114 optically coupled to inject an image into an LOE (interchangeably referred to as a "waveguide," "substrate," or "slab") 10, within which LOE 10 image light is captured in one dimension by internal reflection at a set of planar outer surfaces that are parallel to one another.

Within the LOE 10, the optical aperture expansion is achieved by one or more arrangements for progressively redirecting the image illumination, typically employing a set of partially reflective surfaces (interchangeably referred to as "facets") that are parallel to each other and inclined obliquely relative to the direction of propagation of the image light, with each successive facet deflecting a portion of the image light into a deflection direction. For one-dimensional aperture expansion, the facets also couple out image light towards the user's eyes. In some cases, as shown herein, two-dimensional aperture expansion is achieved by employing a first set of facets in region 116 to progressively redirect image illumination within the LOE that is also captured/directed by internal reflection. The deflected image illumination then enters a second substrate region 118, which may be implemented as an adjacent different substrate or as a continuation of a single substrate, in which an out-coupling arrangement (e.g., another set of partially reflective facets) progressively couples a portion of the image illumination out towards the eyes of an observer located within a region defined as an eye-movement box (EMB), thereby enabling an optical aperture expansion in a second dimension. Similar functionality may be achieved using diffractive optical elements (diffractive optical element, DOE) to redirect and/or couple image illumination within one or both of regions 116 and 118.

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

Reference is made herein to the X-axis extending horizontally (fig. 1A) or vertically (fig. 1B) in the general direction of extension of the first region of the LOE and to the Y-axis extending perpendicular to the X-axis, i.e. vertically in fig. 1A and horizontally in fig. 1B. In very similar terms, it is believed that the first region 116 of the first LOE or LOE 10 achieves aperture expansion in the X-direction, while the second region 118 of the second LOE or LOE 10 achieves aperture expansion in the Y-direction. The details of the expansion of the angular direction of propagation of the different parts of the field of view will be more precisely described below. It should be noted that the orientation as shown in fig. 1A may be considered a "top-down" implementation in which the image illumination into the main (second region) of the LOE enters from the upper edge, while the orientation shown in fig. 1B may be considered a "lateral injection" implementation in which an axis, referred to herein as the Y-axis, is deployed horizontally. In the remaining figures, various features of certain embodiments of the present invention will be shown in the context of a "top-down" orientation similar to that of fig. 1A. However, it should be appreciated that all of these features are equally applicable to lateral implantation implementations that also fall within the scope of the invention. In some cases, other intermediate orientations are also suitable and are included within the scope of the present invention unless explicitly excluded. The two-dimensional expansion embodiment shown here is merely exemplary, but the invention is also applicable to embodiments in which the LOE performs only single-dimensional aperture expansion.

It should be appreciated that the near-eye display 100 includes various additional components, typically including a controller 122 for actuating the image projector 114, which controller 122 typically employs power from a small on-board battery (not shown) or some other suitable power source. It should be understood that the controller 122 includes all necessary electronic components, such as at least one processor or processing circuit, for driving the image projector.

Aspects of the invention relate to implementations of the image projector 114, the image projector 114 comprising an image conjugate generator arranged such that the image projector injects both a collimated image and its conjugate image into the LOE 10. Various non-limiting examples of the image conjugate generator will be described below with reference to fig. 3 to 16. Thus, referring to fig. 3, an enlarged schematic partial view of the optical system of fig. 1 for directing an image toward a user for viewing is shown. The optical system comprises an LOE 10, which LOE 10 is formed of a transparent material and has a first main outer surface 11a and a second main outer surface 11b parallel to each other for supporting the propagation of an image by internal reflection at these surfaces. The LOE 10 also has: a coupling-out arrangement (in region 118 of fig. 1, as described above but not shown here) for coupling out the image towards the eyes of the user; and a coupling aperture 15, in this case the coupling aperture 15 is shown as a side edge of the LOE 10.

Rather than rely on structures integrated with the LOE10 to generate image and conjugate pairs, the image projector 114 according to this aspect of the invention includes an image conjugate generator to generate image and conjugate pairs before a collimated or conjugate image impinges on either of the major outer surface 11a and the major outer surface 11b of the LOE 10.

Thus, in the example of fig. 3, image projector 114 includes: an image generator 32 for generating an image; collimation optics 31 for collimating the image; and an image conjugate generator, here implemented as a second image generator 33 that generates conjugate images. In the example shown here, image generator 32 and image generator 33 share a common collimation optics 31. The image projector 114 is coupled to the coupling aperture 15 to introduce the collimated image, or a conjugate image thereof, directly into the LOE10 before the collimated image, or a conjugate image thereof, impinges on either of the major outer surface 11a and the major outer surface 11b of the LOE 10.

It will be appreciated that this solution is in sharp contrast to the incoupling arrangement of fig. 2A and 2B, in which the conjugate image is generated within the LOE itself by reflection from the main outer surfaces (or surfaces of the coupling prisms, which are continuations of these main outer surfaces and are defined herein as part of the main outer surfaces of the LOE for this purpose).

The two image generators 32 and 33 are driven to generate the same image with one of them inverted, and each field is identically shown from the two fields. Active alignment is used during assembly of the device, preferably by mechanical adjustment or more preferably by digital correction of the image display position, to move the two images on the image generator so that they are aligned as complementary conjugate images within the LOE. Thus, the LOE is "filled" with the primary image and its conjugate extending radially through the LOE from the coupling aperture, without any extension of the LOE being required to achieve such filling.

The previous disclosure implements an "image conjugate generator" as at least one reflective surface discontinuous with the main outer surface to generate a conjugate image. The term "image generator" in the context of the present disclosure then means any type of microdisplay image generator known in the art. Suitable examples include, but are not limited to: a spatial light modulator (spatial light modulator, SLM) comprising a transmissive SLM, such as an LCD display, and a reflective SLM, such as an LCOS display; and active light emitting displays such as OLED displays. A scanned image generator in which a fast scanning laser beam is modulated synchronously with its scanning movement can also be used as an image generator according to the invention. In such a system, the optical arrangement shown in FIG. 3 is arranged such that a single scanning mirror is located in a plane that is optically imaged onto 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. The present disclosure does not contemplate embodiments that include only one image generator incorporating at least one reflective surface to include an image conjugate generator, where the at least one reflective surface reflects an image projected by the one image generator to produce a conjugate image. Rather, the present disclosure discloses various embodiments, including: (1) at least two image generators, (2) two images sequentially generated by the same generator, or (3) a single matrix of two images simultaneously generated.

For example, fig. 4A and 4B show a one-dimensional (i.e., uniaxially expanded) LOE 10 having only two reflective surfaces 11a and 11B. The embodiment of fig. 4A uses a reflective surface 29 (e.g., the bottom surface of prism 14) to create the conjugate image. The image generator generates a light beam that is actually split into two parallel beams. The first beam enters the LOE 10 via an aperture 15. The second beam is reflected by the reflective surface 29 to produce a conjugate beam that enters the LOE 10 via the aperture 15 along with the first beam. In practice, the reflective surface 29 creates two conjugate apertures 15a, 15b through which the first and conjugate beams may enter the LOE 10, respectively. The first and conjugate beams may then propagate at precisely opposite angles and be reflected by both surfaces 11a and 11b until the facets reflect the beams out to the user's eyes. On the other hand, the embodiment of fig. 4B includes a second image generator 33 for generating a 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 light beam from the image generator 32 enters the LOE 10 via the aperture 15. The second conjugate beam from conjugate generator 33 enters the LOE 10 via aperture 15 along with the first beam. The first and conjugate beams may then propagate at precisely opposite angles and be reflected by both surfaces 11a and 11b until the facets reflect the beams out to the user's eyes. In this way, the reflector 29 is not required, potentially reducing the size and complexity of the optics. A single image generation matrix 114 may also be used, where 32 and 33 are images generated side-by-side within the one matrix. These images are generated as mirror images of each other (schematically depicted by the thick arrows).

In another example, fig. 5A and 5B show a two-dimensional LOE10 (vortex light-guiding optical element (VLOE)) with four reflective surfaces 11a to 11d as disclosed in U.S. patent application No. 16/172,897 published as U.S. patent No. 10,564,417. VLOE are multi-dimensional (i.e., multiaxial expansion) light guide optical elements.

The embodiment of fig. 5A uses two reflective surfaces 27, 29 (e.g., two reflective surfaces of a prism) to produce a conjugate image. The image generator generates a light beam that is actually split into four beams. The first light beam enters VLOE10 via aperture 15. The second beam is reflected by the reflective surface 27, producing a conjugate beam that enters the VLOE10 via the aperture 15 together with the first beam. The third beam is reflected by the reflective surface 29, producing a conjugate beam that enters the VLOE10 via the aperture 15 together with the first and second beams. The fourth beam is reflected by the two reflecting surfaces 27, 29, producing a conjugate beam that enters the VLOE10 via the aperture 15 together with the first, second and third beams. In practice, the reflective surfaces 27, 29 create four conjugate apertures 15a to 15d through which the first and conjugate beams may enter the VLOE10. The four beams may then propagate at precisely opposite angles and be reflected simultaneously by surfaces 11a through 11d until the facets reflect the beams out of VLOE10. Here again, 114 may be a single matrix, where 32 and 33 are images within the matrix.

However, the embodiment of fig. 5B includes a second image generator 33, a third image generator 34, and a fourth image generator 35 for generating conjugate images. The image projector 114 comprises an image generator 32 generating a light beam, a second image generator 33 generating a conjugate light beam, a third image generator 34 generating a further conjugate light beam, and a fourth image generator 35 generating a further conjugate light beam. The first light beam from image generator 32 enters VLOE10 via aperture 15. The conjugate beams from conjugate generator 33, conjugate generator 34, and conjugate generator 35 enter VLOE10 via aperture 15 together with the first beam. The first and conjugate beams may then propagate at precisely opposite angles and be reflected simultaneously by surfaces 11a through 11d until the facets reflect the beams out of VLOE10. In this way, the reflector 27, 29 is not required, potentially reducing the size and complexity of the optics.

Thus, also, the term "image generator" in the context of the present disclosure means any type of micro-display image generator known in the art. While the previous disclosure may have used at least one reflective surface that is discontinuous with the main outer surface to generate the conjugate image, the present disclosure 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. When testing the optical arrangement, the exact placement and magnification of the image and conjugate image will be electronically calibrated. Therefore, high-precision optical placement is not required.

In one embodiment, image generator 32, image generator 33, etc. may project images of different polarizations and conjugate images (e.g., by using different waveplates in each matrix) to generate polarization mixtures in LOE 10. Such polarization mixing in the LOE 10 may be used to facilitate depolarization to counteract polarization that may be introduced by optical elements within the LOE 10. Depolarization may also be achieved by introducing at least one active or passive depolarizer in the optical system.

Such an embodiment comprising at least two image generators 32, 33 may also be combined with a reflective surface. For example, fig. 6 shows a hybrid embodiment using both the reflective surface 29 and the second image generator 33 to generate the conjugate image. Fig. 6 shows a two-dimensional VLOE 10 with four reflective surfaces 11a to 11 d. Projector 114 employs separate generators 32, 33 to generate the light beam and its conjugate light beam. The first beam 32 and its conjugate 33 enter the VLOE 10 via the aperture 15. The first beam and its conjugate beam are reflected by the reflective surface 29 to produce a conjugate beam that enters the VLOE 10 via the aperture 15. In practice, the reflective surface 29 creates two apertures: the generated first and conjugate beams may each enter the aperture 15a of the VLOE 10 via it; and through which the reflected conjugate beam may enter aperture 15b of VLOE 10. The first and conjugate beams may then propagate at precisely opposite angles and be reflected simultaneously by surfaces 11a through 11d until the facets reflect the beams out of VLOE 10. Thus, coupling an image into VLOE 10 may be achieved by a hybrid combination of optical multiplication and digital image multiplication as shown in FIG. 6. The appropriate method depends on the angle of the image propagating in the LOE 10. In general, but not always, for steep angles, image optical (i.e., reflection) multiplication may be preferred, while for shallow propagation images, digital (i.e., second image generator) multiplication may be preferred.

Returning to fig. 3, two image generators 32, 33 are shown projecting images from a direction directly in front of the LOE 10. That is, the two image generators 32, 33 are disposed symmetrically to each other about the longitudinal center axis α of the LOE 10 and on a plane pi orthogonal to the main outer surface 11a and the main outer surface 11 b. However, this topology (projecting the image from a direction directly in front of the LOE 10) may not be ideal for many near-eye display applications. The present disclosure then discloses embodiments in which the image generator is arranged to project images from directions not directly in front of the LOE 10, for example. Fig. 7 to 15 show examples of such embodiments.

Fig. 7 shows an embodiment in which the primary image and its conjugate image are coupled into the LOE 10 using a reflective surface 25 (i.e., lateral coupling) within the LOE 10. Light from a source 20 (e.g., laser scanner, LED, etc.) is collected by optics 22 (e.g., lens, light pipe, etc.) to illuminate an image generator 32 and a conjugate image generator 33 (e.g., LCOS, DLP, etc.). In some implementations, image generator 32, image generator 33 (e.g., LCOS, LCD, etc.) may generate their own illumination (e.g., OLED, micro LED, etc.) without source 20 or optics 22. In the case where the source is a collimated laser, the generators 32, 33 may also correspond to a scanning mirror and a Micro Lens Array (MLA). In the illustrated embodiment, light from source generators 32, 33 is collimated by collimating optics 31 and injected into the LOE 10.

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 collimating optics 31 for collimating the image. In the example shown here, image generator 32 and image generator 33 share a common collimation optics 31. Light from the image generator 32, the image generator 33 is coupled into the LOE 10 to introduce the collimated image and its conjugate image directly into the LOE 10 before the collimated image and its conjugate image impinge on either of the major outer surface 11a and the major outer surface 11 b. The first and conjugate beams may then propagate at opposite angles and be reflected simultaneously by surfaces 11a, 11b until facet 56 reflects the beam out of LOE 10. The LOE 10 has a reflective surface 25 with a dielectric or metallic coating built into it. The entrance pupil in this configuration is defined by the reflective surface 25. In this configuration, the spacing between the optics 31 and the upper surface 11a of the LOE 10 is set to maintain reflectivity within the LOE 10. Reflectivity within the LOE 10 may be achieved by total internal reflection or a coating. As can be readily appreciated from fig. 7, the image generators 32, 33 are arranged to project images from the side rather than from the direction directly in front of the LOE 10.

Fig. 8 shows an implementation similar to fig. 7 but utilizing a mirror 44 to couple the primary image and its conjugate image into the LOE 10. Light from source 20 is collected by optics 22 to illuminate 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 light to be injected into LOE 10 via aperture 15. The mirror 44 is set at an appropriate angle to introduce the primary and conjugate images into the LOE 10 before they impinge on either of the primary and outer surfaces 11a, 11 b. The collimated and conjugate beams may then propagate at opposite angles and be reflected simultaneously by surfaces 11a, 11b until facet 56 reflects the beam out of LOE 10. As can be readily appreciated from fig. 8, the image generators 32, 33 are arranged to project images from the side rather than from the direction directly in front of the LOE 10.

Fig. 9 shows an implementation similar to fig. 7 and 8 but utilizing a tilting mirror 44 on a pivot 45. Mirror 44 may be made to pivot between two angles in cooperation with image generators 32, 33 at a suitable rate (e.g., 30 times per second, 60 times per second, 120 times per second, etc.), thereby enabling the light beams from image generators 32, 33 to be coupled in sequentially. This approach enables a significant reduction in the size of the optics 31, with only one of the image or conjugate image having to be transmitted at any one time.

The image generator 32 generates an image in cooperation with a pivoting mirror 44 set to a suitable angle for inserting an image via the aperture 15. Light from the image generator 32 is coupled into the LOE10 to introduce a collimated image into the LOE10 before the collimated image impinges on either of the major outer surface 11a and the major outer surface 11 b. Thereafter, the pivoting mirror 44 pivots to an appropriate angle for inserting the conjugate image via the aperture 15. The image generator 33 generates the conjugate image in cooperation with a pivoting mirror 44 set to a suitable angle for inserting the conjugate image via the aperture 15. Light from the image generator 33 is coupled into the LOE10 to introduce a conjugated image into the LOE10 before the conjugated image impinges on either of the major outer surface 11a and the major outer surface 11 b. The collimated image and conjugate beam may then propagate at opposite angles and be reflected simultaneously by surfaces 11a, 11b until facet 56 reflects the beam out of LOE 10. With the pivoting mirror 44 pivoted at a sufficiently high rate, the viewer will perceive a resulting image output by facet 56 that is similar to the image output by the system of fig. 7 and 8.

In alternative embodiments, the concepts shown may be used to generate four or more conjugated images to be injected into the LOE 10. Image generator 32 may generate an image in cooperation with a pivoting mirror 44 set to a suitable angle for inserting an image via aperture 15. Light from the image generator 32 is coupled into the LOE10 to introduce a collimated image into the LOE10 before the collimated image impinges on either of the major outer surface 11a and the major outer surface 11 b. Thereafter, the pivoting mirror 44 is pivoted to a suitable angle for inserting the first conjugate image via the aperture 15. The image generator 33 generates the first conjugate image in cooperation with a pivoting mirror 44 set to a suitable angle for inserting the first conjugate image via the aperture 15. Light from the image generator 33 is coupled into the LOE10 to introduce a first conjugate image into the LOE10 before the first conjugate image impinges on either of the major outer surface 11a and the major outer surface 11 b. Thereafter, the pivoting mirror 44 pivots to an appropriate angle for inserting the second conjugate image via the aperture 15. The image generator 32 generates the second conjugate image in cooperation with a pivoting mirror 44 set to a suitable angle for inserting the second conjugate image via the aperture 15. Light from the image generator 32 is coupled into the LOE10 to introduce a second conjugated image into the LOE10 before the second conjugated image impinges on either of the major outer surface 11a and the major outer surface 11 b. Thereafter, the pivoting mirror 44 pivots to an appropriate angle for inserting the third conjugate image via the aperture 15. The image generator 32 generates the third conjugate image in cooperation with a pivoting mirror 44 arranged at a suitable angle for inserting the third conjugate image via the aperture 15. Light from the image generator 33 is coupled into the LOE10 to introduce a third conjugated image into the LOE10 before the third conjugated image impinges on either of the major outer surface 11a and the major outer surface 11 b. The collimated and conjugate images may then propagate along the LOE10 (e.g., VLOE) until the facets 56 reflect the light beam out of the LOE 10.

As can be readily appreciated from fig. 9, the image generators 32, 33 are arranged to project images from the side rather than from the direction directly in front of the LOE 10. It is also possible to use only one image generator 32 (without the image generator 33) and the scan mirror is flipped between the two orientations while the image generator is flipped between the two mirror images.

Fig. 10 shows an implementation using a polarizing beam splitter (polarizing beam splitter, PBS) as disclosed in U.S. patent application No. 12/092,818 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 scanning laser mirror), the refocusing reflective lens 55, and the image generating matrix 114. The second PBS53 is disposed between the matrix 114 and the collimating reflective lens 57. Here, similar to the embodiment of fig. 5B, the matrix 114 generates a plurality of images (a main image and one or more conjugate images). In the view of fig. 10 only two image generators 32, 33 are visible, but additional image generators may be provided along the axis into the page.

In effect, p-polarized light from source 20 is transmitted through PBS 51 and is incident on refocusing reflective lens 55, which refocusing reflective lens 55 reflects and converts the incoming light beam. The reflected light beams (now s-polarized) are reflected from the PBS 51 and the PBS53 to illuminate the image generator matrix 32 and the conjugate image generator matrix 33. In some embodiments, the image generator matrix 32, 33 may generate their own illumination without the source 20. Light (now p-polarized) from source generator matrix 32, source generator matrix 33 is transmitted through PBS53 and collimated and reflected by collimating reflective lens 57. Finally, the reflected beam (now s-polarized) reflects from the PBS53 to enter the LOE 10 via the aperture 15. The collimated and conjugate beams may then propagate at opposite angles and be reflected by the surface along the LOE 10 at the same time until the facets 56 reflect the beams out of the LOE 10. As can be readily appreciated from fig. 10, the image generators 32, 33 are arranged to project images from the side rather than from the direction directly in front of the LOE 10.

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

Fig. 12A-12C illustrate another implementation of the techniques of the present invention. Fig. 12A to 12C show the following embodiments: where image generator 32, 33 are not part of the same matrix 114, but rather, matrix 114 has been divided into a matrix 114a and a matrix 114b. The image generator 32 forms part of the first matrix 114a and the conjugate generator forms part of the second matrix 114b. The two matrices 114a, 114b are smaller than the single matrix 114 described in the previous embodiments. This reduced size and the flexibility of being able to position the first matrix 114a and the second matrix 114b independently of each other yields significant design advantages.

In fig. 12A to 12C, light corresponding to the first image generator 32 is shown with solid arrows, and light corresponding to the conjugate image generator 33 is shown with broken arrows. In the configurations of fig. 12A to 12C, the optical prisms 114a and 114b and the LCOS matrices 32, 33 are tilted, and the collimating reflective lens 57 and the collimating reflective lens 58 are also tilted. This tilt enables the illustrated embodiment to contain all light beams in a small optical arrangement while maintaining good quality, since all light beams interact almost perpendicularly with optics 57, optics 58 and prisms 114a, 114 b. 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, 114 b. The second PBS 53 is disposed between the prisms 114a and 114b and the collimating and reflecting lenses 57 and 58.

Fig. 12B shows a ray diagram (i.e., a main image) associated with the image generator 32, and fig. 12C shows a ray diagram (i.e., a conjugate image) associated with the conjugate image generator 33. In effect, p-polarized light from source 20 is transmitted through PBS 51 to matrix 114a to illuminate image generator 32. The image generated by image generator 32 is s-polarized and, therefore, the s-polarized image is reflected from PBS 51 and PBS 53 to collimating reflective lens 57. Collimated light (now p-polarized) reflected from lens 57 is transmitted through PBS 53 to enter LOE 10 (only a portion of LOE 10 is shown) via aperture 15. At the same time, s-polarized light from source 20 is reflected from PBS 51 to matrix 114b to illuminate conjugate image generator 33. The image generated by the conjugate image generator 33 is p-polarized, and thus the p-polarized image is transmitted through the PBS 51 and the PBS 53 to the collimating reflective lens 58. Collimated light (now s-polarized) reflected from lens 58 is reflected from PBS 53 to enter LOE 10 via aperture 15.

The collimated and conjugated light beam may then propagate at opposite angles and be reflected by the surface along the LOE 10 at the same time until the facets 56 reflect the light beam out of the LOE 10. As can be readily appreciated from fig. 12A to 12C, the image generators 32, 33 are arranged to project images from the side rather than from the direction directly in front of the LOE 10.

Fig. 13A-13C illustrate an embodiment of the present invention in which a single matrix 114 is multiplexed in time to sequentially generate an image and a conjugate image. Two adjacent PBSs 51, 53 are used. The first PBS 51 is disposed between the light source 20 (e.g., an 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 PBS53 is disposed between the liquid crystal switch 60 and the collimating and reflecting lenses 57, 58. In the configuration of fig. 13A to 13C, the collimating reflective lens 57 and the collimating reflective lens 58 are inclined. This tilting enables the illustrated embodiment to contain all light beams in a small optical arrangement while maintaining good quality, since all light beams interact almost perpendicularly with optics 57, optics 58 and matrix 114.

Fig. 13B shows a light ray diagram associated with the image generator 32/33 when it generates a main image, and fig. 13C shows a light ray diagram associated with the image generator 32/33 when it generates a conjugate image.

To transmit the primary image (fig. 13A and 13B), p-polarized light (large arrow) from 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 thus reflected from PBS 51 toward switch 60. In the case of the main image, the crystal switch 60 maintains polarization (s-polarization), and thus, light (solid arrow) is reflected from the PBS53 to the collimating reflective lens 57. Collimated light (now p-polarized) (dashed arrow) reflected from lens 57 is transmitted through PBS53 to enter LOE 10 via aperture 15. Thereafter, to transmit the conjugate image (fig. 13A and 13C), p-polarized light (large arrow) from source 20 is transmitted through PBS 51 to matrix 114 to illuminate image generator 33. The conjugate image (solid arrow) generated by the image generator 33 is s-polarized light and is thus reflected from the PBS 51 toward the switch 60. In the conjugate case, the crystal switch 60 rotates the polarization of the light (now p-polarized), and thus, the light (dashed arrow) is transmitted through the PBS53 to the collimating reflective lens 58. Collimated light (now s polarized) reflected from lens 58 (solid arrows) reflects from PBS53 to enter LOE 10 via aperture 15. By rapidly switching between the two configurations (switch 60 and the appropriate image on matrix 14), the illumination on LOE 10 will be perceived as if it were both an image and a conjugate image.

The collimated and conjugated light beam may then propagate at opposite angles and be reflected by the surface along the LOE 10 at the same time until the facets 56 reflect the light beam out of the LOE 10. As can be readily appreciated from fig. 13A-13C, the image generator 32/33 is configured to project images from a lateral direction rather than from a direction directly in front of the LOE 10.

Fig. 14A to 14C show an embodiment equivalent to that of fig. 13A to 13C, but here the PBS 53 is split into two PBSs 53A and 53b. The operation is the same as that of fig. 13A to 13C described above, except that the main image beam is reflected by 53A and the conjugate image beam is reflected by 53b. Thus, the illumination on the matrix 114 for the two alternatives is overlapping. According to this embodiment, separate PBSs 53a, 53b may be implemented onto the dual matrix configurations 114a and 114b (see fig. 12A-12C) to achieve the same illumination orientation of the primary and conjugate images to increase the illumination coupling efficiency.

As can be readily appreciated from fig. 14A-14C, the image generator 32/33 is configured to project images from a lateral direction rather than from a direction directly in front of the LOE 10.

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

Fig. 15 shows an embodiment utilizing a scanning laser 10 on an LCOS matrix 114. Such a configuration may achieve high light coupling efficiency (characterized by a large pixel count of LCOS 114) at high resolution. In the illustrated embodiment, only the primary image rays are shown for clarity. Two beams are generated by two lasers 70. The beam is focused by lens 22, passed through mirror scanner 80, and reflected by PBS 51 onto matrix 114. The two beams generate two images on the matrix 114 and at the same time the matrix 114 is modulated to further improve the image resolution. The two beams are transmitted through the PBS 51, refocused by the reflective lens 55, and 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 beam fills the aperture 15 of the LOE 10. The collimation optics 31 collimate the light beam prior to its injection into the LOE 10.

The use of two beams to generate the shown main image and conjugate image has substantial benefits: 1) The scan speed is increased so that minimal flicker perception is visible, and 2) the use of two beams reduces the actual aperture size, thereby reducing the need for a widely divergent MLA 44. In extreme cases (small aperture 15 or large initial beam), the MLA 44 may not be required.

The configuration of fig. 15 may be used when the LCOS114 is illuminated with an LED. Further, this configuration may be used with sequential single image generation as described above.

Another solution of a system in which images and their conjugates are angularly separated from each other is shown in fig. 16A to 16C. Fig. 16A shows a light ray diagram including both a main image and a conjugate image. Fig. 16B and 16C show ray diagrams respectively showing a main image and a conjugate image independently. The system of fig. 16A-16C includes an angle selective mirror 82 disposed in front of the aperture 15. The mirror 82 may have a coating designed such that it will reflect the light beam of the image propagating at a particular angle (e.g., shallow angle), while the coating is transparent to light beams propagating at other angles (e.g., steep angles). Such coatings are designed and shown in International application No. PCT/IL2004/000813 published as WO 2005/024991 and International application No. PCT/IL2015/051222 published as WO 2016/103251.

In operation, the image generator 32 (e.g., SLM) generates a primary image (fig. 16B). The s-polarized image is reflected from the PBS 51 to a collimating reflective lens 57. The collimated light (now p-polarized) reflected from lens 57 is transmitted through PBS 51, through angle selective mirror 82 (because the angle is very steep, nearly perpendicular) and reaches mirror 44, and mirror 44 reflects the light back toward angle selective mirror 82. At this time, the light reaches the angle selection mirror 82 at a shallow angle, and thus the light is reflected toward the aperture 15. At the same time, the image generator 33 (e.g., SLM) generates a conjugate image (fig. 16C). The s-polarized image is reflected from the PBS 51 to a collimating reflective lens 57. The collimated light (now p-polarized) reflected from lens 57 is transmitted through PBS 51 through angle-selective mirror 82 (because the angle is very steep, nearly perpendicular) to aperture 15. Meanwhile, the image generator 33 generates a conjugate image (fig. 16C). Thus, on the LCOS114, the two images will occupy close portions, and the total area of the LCOS114 can be reduced.

Definition of the definition

The following includes definitions of selected terms employed herein. This definition includes various examples or forms of components that fall within the scope of the terms and that may be used in an implementation. The examples are not intended to be limiting. Both singular and plural forms of terms may be within the definition.

An "operable connection" or a connection through which an entity is "operably connected" is one in which signals, physical communications, or logical communications may be sent or received. Typically, the operable connection comprises a physical interface, an electrical interface, or a data interface, but it should be noted that the operable connection may comprise different combinations of these or other types of connections sufficient to allow 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 processors, operating systems, logic, software, or other entities. Logical or physical communication channels may be used to create the operative connection.

To the extent that the term "includes" or "including" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term "or" (e.g., a or B) is used in the specification or the claims, it is intended to mean "a or B or both. When applicants intend to indicate "a only or B, not both", then the term "a only or B, not both" will be used. Thus, the use of the term "or" herein is intended to be inclusive, rather than exclusive, of the use. See Bryan a. Gamner, modern legal usage dictionary 624 (second edition, 1995).

Although example systems, methods, etc. have been illustrated by description of examples and while the examples have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope to such detail. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the systems, methods, and so forth described herein. Additional advantages and modifications will readily appear to those skilled in the art. The invention is therefore not limited to the specific details, representative apparatus and illustrative examples shown and described. Accordingly, the present application is intended to embrace alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, the preceding description is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined by the appended claims and their equivalents.

Claims (18)

1. An optical system for directing an image toward a user for viewing, the optical system comprising:

(a) A light guiding optical element (LOE) formed of a transparent material and having at least a first and a second major outer surface parallel to each other for supporting propagation of an image by internal reflection at the first and second major outer surfaces, the LOE having a coupling-out arrangement for coupling out the image towards the user's eye, the LOE having a coupling-in arrangement;

(b) An 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 coupled to the coupling-in aperture to introduce the image and its conjugate image into the coupling-in aperture before the image and the conjugate image impinge on either of the at least first and second major outer 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 10.

2. The optical system of claim 1, wherein the LOE further comprises an incoupling reflector disposed obliquely with respect to the first and second major outer surfaces such that light from the image projector is incoupled into the LOE from a side of the first major outer surface or a side of the second major outer surface.

3. The optical system of claim 1, the system comprising:

a coupling-in reflector disposed obliquely with respect to the first and second major outer surfaces; and

A pivot operatively connected to the in-coupling reflector and configured to sequentially pivot the in-coupling reflector in coordination with the image generator and the image conjugate generator generating the image and the conjugate image.

4. The optical system of claim 1, comprising:

two or more adjacent Polarizing Beam Splitters (PBS), 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 and configured to emit a polarized light beam having a first polarization such that the emitted polarized light beam is transmitted through the first PBS and impinges on the refocusing reflective lens, which reflects an incoming light beam and rotates the polarization of the incoming light beam such that the reflected light beam is reflected from the first PBS toward the second PBS, wherein the reflected light beam is reflected from the second PBS to the image projector to illuminate the image generator and the conjugate image generator, the projected image and the conjugate image being transmitted through the second PBS and impinge on a second refocusing reflective lens, which reflects the incoming light beam and rotates the polarization of the incoming light beam such that the reflected light beam is reflected from the second PBS to the LOE.

5. The optical system of claim 1, wherein the image projector comprises the image generator and at least three conjugate image generators.

6. The optical system of claim 5, wherein the system interpolates a high resolution raw image into a low resolution sub-image to be generated as the image and the conjugate image.

7. 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 primary exterior surface to generate one or more additional conjugate images.

8. The optical system of claim 1, wherein the image generator and the conjugate image generator are not part of one single matrix, but are disposed at different positions or orientations and project light in different directions.

9. The optical system of claim 1, comprising:

an angle selective mirror provided in front of the coupling-in arrangement and configured to reflect an image beam propagating at a specific angle, while being transparent to beams propagating at other angles,

Wherein the image generator generates an image polarized with a first polarization such that the image is reflected from the PBS to a collimating reflective lens and through the angle selective mirror to a mirror that reflects the image back to the angle selective mirror such that the image is reflected towards the incoupling arrangement.

10. The optical system of claim 1, wherein the image generator and the conjugate image generator correspond to a first laser and a second laser combined with a matrix.

11. The optical system of claim 1, wherein the image generator and the conjugate image generator correspond to a first laser and a second laser combined with a matrix; wherein a first laser irradiates the image and a second laser irradiates the conjugate image, the image beam being focused by a lens and then passed through a mirror scanner to be reflected by the PBS onto a matrix, returned from the matrix through the PBS to be refocused by a reflective lens and reflected by the PBS onto a diffuser or microlens array (MLA).

12. The optical system of claim 1, wherein the image generator and the conjugate image generator are tilted or angled with respect to each other.

13. The optical system of claim 12, comprising one or more collimating reflective lenses, wherein the image generator and the conjugate image generator are tilted or angled with respect to each other and with respect to the collimating reflective lenses.

14. An optical system for directing an image toward a user for viewing, the optical system comprising:

(a) A light guiding optical element (LOE) formed of a transparent material and having at least a first major outer surface and a second major outer surface parallel to each other for supporting propagation of an image by internal reflection at the first major outer surface and the second major outer surface, the LOE having an out-coupling arrangement for out-coupling the image towards the user's eye, the LOE having an in-coupling arrangement;

(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 coupling-in aperture to introduce the image and its conjugate image into the coupling-in aperture before the image and the conjugate image impinge on at least any one of the first and second major outer surfaces, the image generator being arranged to project the image and the conjugate image from a direction that is not directly in front of the LOE.

15. The system of claim 14, comprising:

a liquid crystal polarization switch configured to operate in conjunction with the image projector such that the switch does not deflect polarization when the image is generated, rotates polarization when the conjugate image is generated, or deflects polarization when the image is generated, and does not rotate polarization when the conjugate image is generated.

16. The optical system of claim 14, comprising:

a coupling-in reflector disposed obliquely with respect to the first and second major outer surfaces; and

a pivot operatively connected to the in-coupling reflector and configured to sequentially pivot the in-coupling reflector in coordination with the image generator and the image conjugate generator generating the image and the conjugate image.

17. An optical system for directing an image toward a user for viewing, the optical system comprising:

(a) A light guiding optical element (LOE) formed of a transparent material and having at least a first major outer surface and a second major outer surface parallel to each other for supporting propagation of an image by internal reflection at the first major outer surface and the second major outer surface, the LOE having an out-coupling arrangement for out-coupling the image towards the user's eye, the LOE having an in-coupling arrangement;

(b) An image projector for generating an image and a conjugate image of the image, the image projector being coupled to the coupling-in aperture to introduce the image and its conjugate image into the coupling-in aperture before the image and the conjugate image impinge on either of the at least first and second major outer surfaces, the image projector being arranged to project the image and the conjugate image, respectively, from a direction that is not directly in front of the LOE.

18. The system of claim 17, wherein the image projector is a single Liquid Crystal On Silicon (LCOS) matrix that generates two mirrors side-by-side.