Backlighting subsystem for use with a near-eye display

Abstract

A backlighting system includes a light source, a concave reflector, a quarter-wave plate, and a reflective linear polarizer. The light source generates light that impinges directly upon the concave reflector. The quarter-wave plate is located and oriented so as to receive the light reflected from the concave reflector. The reflective linear polarizer is located and oriented to receive light transmitted through the quarter-wave plate. The reflective linear polarizer provides for reflecting light reflected from the concave reflector and transmitted through the quarter-wave plate having a first polarization direction, back through the quarter-wave plate to be reflected from the concave reflector. The reflective linear polarizer provides for transmitting light reflected from the concave reflector and transmitted through the quarter-wave plate having a second polarization direction that is orthogonal to the first polarization direction, and the quarter-wave plate provides for converting linearly-polarized light to circularly-polarized light, and vice versa.

Description

BACKLIGHTING SUBSYSTEM FOR USE WITH A NEAR-EYE DISPLAYCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The instant application claims the benefit of prior U.S. Provisional Application Serial No. 63 / 700,613 filed on 27 September 2024, which is incorporated herein by reference in its entirety.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] In the accompanying drawings:

[0003] FIG. 1 illustrates a schematic cross-sectional view of a backlighting subsystem incorporated in a near-eye display system, wherein the backlighting subsystem is used to illuminate an associated Liquid-Crystal Display (LCD) non-emissive image-display panel of the near-eye display system;

[0004] FIG. 2 illustrates an exploded cross-sectional view of the backlighting system illustrated in FIG. 1;

[0005] FIG. 3a illustrates a solid 3-D-view of an aspheric concave first-surface mirror of the backlighting subsystem illustrated in FIGS. 1 and 2;

[0006] FIG. 3b illustrates a wireframe oblique-view of the aspheric mirror of the backlighting subsystem illustrated in FIGS. 1, 2, and 3a;

[0007] FIG. 3c illustrates a wireframe plan-view of the aspheric mirror of the backlighting subsystem illustrated in FIGS. 1, 2, 3a and 3b, and further illustrates a dashed line representing an outline of the associated Liquid Crystal Display (LCD);

[0008] FIG. 4 illustrates a ray tracing of a plurality of light rays within the cross-sectional view of the backlighting subsystem illustrated in FIGS. l-3a for light emanating from an associated extended light source thereof, but with the associated light rays traced backwards from two locations at the Liquid Crystal Display (LCD) back to the extended light source;

[0009] FIG. 5a illustrates a magnified view of a first portion of the cross-sectional view of FIG. 4, showing light rays generated by the backlighting system propagating through a relatively central pixel of the Liquid Crystal Display (LCD);

[0010] FIG. 5b illustrates a magnified view a second portion of the cross-sectional view of FIG. 4, showing light rays generated by the backlighting system propagating through an edge pixel of the Liquid Cry stal Display (LCD);

[0011] FIG. 6 illustrates a cross-sectional view of a first embodiment of a near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, and further illustrates a ray tracing of a plurality of light rays within the first-embodiment near-eye display system for lightemanating from an associated extended light source of the backlighting subsystem, but with the associated light rays traced both forwards and backwards from three locations at the Liquid Crystal Display (LCD) back to the extended light source and forwards to an exit pupil, wherein the first- embodiment near-eye display system incorporates a first embodiment of a catadioptric optical magnifier;

[0012] FIG. 7a illustrates a cross-sectional view of the first-embodiment catadioptric optical magnifier illustrated in FIG. 6;

[0013] FIG. 7b illustrates an exploded cross-sectional view of the first-embodiment catadioptric optical magnifier illustrated in FIGS. 6 and 7a;

[0014] FIG. 8 illustrates a second embodiment of a catadioptric magnifier, for which the eye- proximate surface thereof is flat;

[0015] FIG. 9a illustrates a vertical cross-sectional view of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4 and 6. and further illustrates a ray tracing of a plurality of light rays within the first-embodiment near-eye display system for light emanating from an associated extended light source of the backlighting subsystem, but with the associated light rays traced backwards from three locations on the associated exit pupil back to the extended light source, wherein the first-embodiment near-eye display system incorporates a first-embodiment catadioptric optical magnifier with a 20 millimeter exit pupil;

[0016] FIG. 9b illustrates the first-embodiment near-eye display system illustrated in FIG. 9a, together with the subset of light rays thereof associated with a first vertical edge location on the associated exit pupil;

[0017] FIG. 9c illustrates the first-embodiment near-eye display system illustrated in FIG. 9a, together with the subset of light rays thereof associated with a relatively-central location on the associated exit pupil;

[0018] FIG. 9d illustrates the first-embodiment near-eye display system illustrated in FIG. 9a, together with the subset of light rays thereof associated with a second vertical edge location on the associated exit pupil;

[0019] FIG. 10a illustrates a vertical cross-sectional view of a second embodiment of a near- eye display system incorporating a backlighting subsystem similar to that illustrated in FIGS. 1- 4, 6, and 9a-d, and further illustrates a ray tracing of a plurality of light rays within the second- embodiment near-eye display system for light emanating from an associated extended light source of the backlighting subsystem, but with the associated light rays traced backwards from three locations on the associated exit pupil back to the extended light source, wherein the second-embodiment near-eye display system incorporates a first-embodiment catadioptric optical magnifier with a 15 millimeter exit pupil;

[0020] FIG. 10b illustrates the second-embodiment near-eye display system illustrated in FIG. 10a, together with the subset of light rays thereof associated with a first vertical edge location on the associated exit pupil;

[0021] FIG. 10c illustrates the second-embodiment near-eye display system illustrated in FIG. 10a, together with the subset of light rays thereof associated with a relatively-central location on the associated exit pupil;

[0022] FIG. lOd illustrates the second-embodiment near-eye display system illustrated in FIG. 10a, together with the subset of light rays thereof associated with a second vertical edge location on the associated exit pupil;

[0023] FIG. Ila illustrates a vertical cross-sectional view of a third embodiment of a near-eye display system incorporating a backlighting subsystem similar to that illustrated in FIGS. 1-4, 6, 9a-d, and lOa-d, and further illustrates a ray tracing of a plurality of light rays within the third- embodiment near-eye display system for light emanating from an associated extended light source of the backlighting subsystem, but with the associated light rays traced backwards from three locations on the associated exit pupil back to the extended light source, wherein the third- embodiment near-eye display system incorporates a first-embodiment catadioptric optical magnifier with a 10 millimeter exit pupil;

[0024] FIG. 11b illustrates the third-embodiment near-eye display system illustrated in FIG. Ila, together with the subset of light rays thereof associated with a first vertical edge location on the associated exit pupil;

[0025] FIG. 11c illustrates t the third-embodiment near-eye display system illustrated in FIG. Ila, together with the subset of light rays thereof associated with a relatively-central location on the associated exit pupil;

[0026] FIG. lid illustrates the structural elements of the third-embodiment near-eye display system illustrated in FIG. Ila, together with the subset of light rays thereof associated with a second vertical edge location on the associated exit pupil;

[0027] FIG. 12a illustrates a schematic plan view of the extended light source of the first- embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4 and 6 used to generate the cross-sectional views illustrated in FIGS. 9a-9d and 14a- 14d;

[0028] FIG. 12b illustrates a schematic plan view of an alternative extended light source of a near-eye display system incorporating a backlighting subsystem similar to that illustrated in FIGS. 1-4 and 6;

[0029] FIG. 13a illustrates a schematic plan view of a circular exit pupil — and an associated portion thereof that is viewable without vignetting - of the associated real-imaging subsystem of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4 and 6 used to generate the cross-sectional views illustrated in FIGS. 9a-9d and 14a- 14d, for the extended light source illustrated in FIG. 12a;

[0030] FIG. 13b illustrates a schematic plan view of a rectangular exit pupil - and an associated portion thereof that is viewable without vignetting — of the associated real-imaging subsystem of the alternative near-eye display system incorporating the backlighting subsystem similar to that illustrated in FIGS. 1-4 and 6, for the extended light source illustrated in FIG. 12b;

[0031] FIG. 14a illustrates a horizontal cross-sectional view of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, and 9a-d, and further illustrates a ray tracing of a plurality of light rays within the first-embodiment near-eye display system for light emanating from an associated extended light source of the backlighting subsystem, but with the associated light rays traced backwards from three locations on the associated exit pupil back to the extended light source, wherein the first-embodiment near-eye display system incorporates a first-embodiment catadioptric optical magnifier with a 20 millimeter exit pupil;

[0032] FIG. 14b illustrates the first-embodiment near-eye display system illustrated in FIG. 14a, together with the subset of light rays thereof associated with a first lateral edge location on the associated exit pupil;

[0033] FIG. 14c illustrates the first-embodiment near-eye display system illustrated in FIG. 14a, together with the subset of light rays thereof associated with a relatively-central location on the associated exit pupil;

[0034] FIG. 14d illustrates the first-embodiment near-eye display system illustrated in FIG. 14a, together with the subset of light rays thereof associated with a second lateral edge location on the associated exit pupil;

[0035] FIG. 15a illustrates a horizontal cross-sectional view of the non-emissive image display panel, optical magnifier, and exit pupil of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, and 14a-d, for light rays emanating from a first lateral point on the non-emissive image display panel, so as to provide for illustrating the bounds of the associated exit pupil of the associated real-imaging subsystem;

[0036] FIG. 15b illustrates a horizontal cross-sectional view of the non-emissive image display panel, optical magnifier, and exit pupil of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, and 14a-d, for light rays emanating from an off-central laterally-displaced point on the non-emissive image display panel, so as to provide for illustrating the bounds of the associated exit pupil of the associated real- imaging subsystem;

[0037] FIG. 15c illustrates a horizontal cross-sectional view of the non-emissive image display panel, optical magnifier, and exit pupil of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, and 14a-d, for light rays emanating from a central point on the non-emissive image display panel, so as to provide for illustrating the bounds of the associated exit pupil of the associated real-imaging subsystem;

[0038] FIG. 15d illustrates a horizontal cross-sectional view of the non-emissive image display panel, optical magnifier, and exit pupil of the first-embodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, and 14a-d, for light rays emanating from a second lateral point on the non-emissive image display panel, so as to provide for illustrating the bounds of the associated exit pupil of the associated real-imaging subsystem;

[0039] FIG. 16 illustrates an isometric view of a housing incorporating a binocular fourthembodiment near-eye display system, each of which incorporates the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, 14a-d, 17, and 18, mounted on the head of a person viewing the near-eye display system;

[0040] FIG. 17 illustrates an isometric view of the hardware components of the fourthembodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, 14a-d, and 18;

[0041] FIG. 18 illustrates an isometric view of the hardware components of the fourthembodiment near-eye display system incorporating the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, 14a-d, and 17, further illustrating light rays associated with five points on the exit pupil during operation of the near-eye display system;

[0042] FIG. 19 illustrates locations on the extended light source associated with the five points on the exit pupil illustrated in FIG. 18;

[0043] FIG. 20 illustrates a commercially available RGB 17-element LED extended light source used to illuminate the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, and 14a-d for generating the image illustrated on the right side of FIG. 21;

[0044] FIG. 21 illustrates a binocular image of test pattern generated with commercially- available RGB LCD panels in cooperation with corresponding off-the-shelf pancake lenses, for which the left LCD panel was illuminated directly with the commercially-available diffuse backlight included with the LCD panel, and the right LCD panel was illuminated with the backlighting subsystem illustrated in FIGS. 1-4, 6, 9a-d, and 14a-d using the extended light source illustrated in FIG. 20;

[0045] FIG. 22 illustrates, for purposes of comparison, a cross-sectional view of a near-eye display system that incorporates an Organic Light-Emitting Diode (OLED) as the associated light source, in cooperation with a second-embodiment catadioptric optical magnifier, and further illustrates a ray tracing of a plurality of light rays within the near-eye display system for light emanating from three pixels of the OLED, wherein the near-eye display system incorporates a 20 millimeter exit pupil;

[0046] FIG. 23a illustrates a magnified view a portion of the cross-sectional view of FIG. 22 showing a range of light rays generated by a relatively-central OLED pixel that can reach an associated exit pupil;

[0047] FIG. 23b illustrates a magnified view a portion of the cross-sectional view of FIG. 22 showing a range light rays generated by an edge OLED pixel that can reach an associated exit pupil; and

[0048] FIG. 24 illustrates a normalized two-dimensional plot of radiation intensity of an OLED pixel as a function of the angle of the radiation, modeled as a Lambertian light source.DET AILED DESCRIPTION

[0049] Referring to FIGS. 1-4. a backlighting subsystem 10 of an associated near-eye display system 100 provides for illuminating an associated Liquid-Crystal Display (LCD) 12 with light 14 generated by an associated extended light source 16 that, for example, comprises a plurality of Light-Emitting Diodes (LED’s) 16’ - more generally, a plurality of localized-light- sources, - wherein the backlighting subsystem 10 further provides for limiting the angular distribution of the light 14 that illuminates the Liquid-Crystal Display (LCD) 12. The backlighting subsystem 10 further incorporates a relatively angled, concave reflector 18 along a first surface 20, for example, a concave first-surface mirror 18.1, that provides for reflecting the light 14 from the extended light source 16, 16’ towards a second set of surfaces 22 of a quarter-wave-plate 24 and a reflective polarizer 26 that, in respective order, abut one another and together abut the Liquid-Crystal Display (LCD) 12, i.e. with the reflective polarizer 26 located between the quarter-wave-plate 24 and the Liquid-Crystal Display (LCD) 12. Theconcave first-surface mirror 18.1 is illustrated as a shaded solid in FIG. 3a, and as a wireframe in FIGS. 3b and 3c, wherein FIG. 3c further illustrates an outline 18.1’ of the associated Liquid- Crystal Display (LCD) 12. The Liquid-Crystal Display (LCD) 12 - acting as a non-emissive image-display panel 12’ comprising a plurality of LCD pixels 28 - provides for displaying thereupon electronic image content 30 from a source 32 thereof, and the near-eye display system 100 further incorporates an optical magnifier 102 that provides for forming a virtual image 104 of the non-emissive image-display panel 12’ for viewing by the eye 106 of a user, wherein the virtual image 104 comprises a plurality’ of image pixels 104’, each of which corresponds to a corresponding LCD pixel 28. The resulting light 14.1 of the virtual image 104 passes through an exit pupil 108 of the near-eye display system 100 that is viewable by the eye 106, wherein the backlighting subsystem 10 provides for limiting or minimizing the amount of light 14 that otherwise would pass outside a viewable portion of the exit pupil 108, absent the limited angular distribution of light 14 provided for by the backlighting subsystem 10. Referring to FIG. 4, the concave reflector 18 is shaped so as to provide for a relatively shallow depth 34 along a fore-aft direction when incorporated in an associated near-eye display system 100 - for example, in one embodiment, a depth 34 of about 16 millimeters when used in cooperation with a Liquid-Crystal Display (LCD) 12 about 65 millimeters (2.56 inches) in diagonal dimension 36.

[0050] As illustrated by FIG. 2 and the light-ray tracings of FIGS. 4, 5a, and 5b, in operation of the backlighting subsystem 10, light 14 from the extended light source 16, 16’ is reflected from the first surface 20 of the concave first-surface mirror 18.1 toward and through the quarter-wave-plate 24. and then reflected and linearly polarized by the reflective linear polarizer 26. The resulting reflected linearly-polarized light 14’ is converted to circularly- polarized light 14” by the quarter-wave-plate 24, and then reflected again from the concave first-surface mirror 18.1 as circularly-polarized light 14’”, but with reversed rotation of the sense of the circular polarization as a result of the reflection, so that after then passing again through the quarter-wave-plate 24, the reflected circularly-polarized light 14”’ is transformed to linearly-polarized light 14”” having a direction of polarization that is aligned with the direction of polarization of the reflective linear polarizer 26 so as to pass therethrough, and then pass through the Liquid-Crystal Display (LCD) 12 / non-emissive image-display panel 12’ and become encoded thereby w ith the electronic image content 30 of the virtual image 104.

[0051] For example, in one set of embodiments, both the quarter-wave-plate 24 and the reflective linear polarizer 26 are each embodied as respective films 24’, 26’, and the quarterwave-plate 24, 24’ is tuned to a mid- visible — e.g. green - wavelength, i.e. wherein the tunedwavelength is the wavelength at which one polarization is retarded by 90 degrees relative to a relatively-orthogonal polarization. In practice, a quarter-wave-plate 24, 24’ tuned for a green wavelength provides for sufficiently effective operation over the range of visible wavelengths.

[0052] If light 14 from the extended light source 16, 16’ is randomly polarized - as likely in practice, - then upon first striking the reflective linear polarizer 26, a substantial amount of unwanted light would pass therethrough, in which case it would be beneficial to first convert the light 14 from the extended light source 16, 16’ to a circular polarization 14c— for example, by optionally converting to linear polarization with an optional transmissive linear polarizer 38 followed by an optional quarter-wave plate 40 - that, after initially passing through the quarter- wave-plate 24 would be converted to linear polarization, which would provide for a more complete reflection by the reflective linear polarizer 26. Alternatively, or additionally, referring to FIG. 2, the backlighting subsystem 10 may optionally incorporate an absorptive or reflective mask 42 surrounding the LCD non-emissive image-display panel 12, 12’ that would prevent light 14 that otherwise might pass through or by the reflective linear polarizer 26 from reaching the face of the user.

[0053] The polarization elements, including the reflective linear polarizer 26 and the quarter-wave plates 24, are selected to provide the desired input polarization to the LCD non- emissive image-display panel 12, 12’. In view of modem LCD panels typically using a reflective linear polarizer to recycle light of the wrong polarization state within a diffuse backlight, it would be relatively simple to add the quarter-wave plate to such an LCD panel, albeit without the diffuse backlight, so that the LCD panel itself provides the substrate for both the reflective linear polarizer 26 and the quarter-wave plate 24 as a single component. Accordingly, instead of being separate distinct elements abutting the LCD non-emissive image-display panel 12, 12’, the reflective linear polarizer 26 and the quarter-wave plates 24 could be either bonded to, or a part of, the LCD non-emissive image-display panel 12, 12’ as layers thereof on a surface thereof.

[0054] Referring also to FIGS. 5a and 5b that respectively illustrate linearly-polarized light 14”” rays propagating through a relative central pixel 28.1, and an edge pixel 28.2 of the Liquid-Crystal Display (LCD) 12, respectively, the illustrated embodiment of the backlighting subsystem 10 provides for limiting the angular spread of light rays either exiting a relatively - central portion of the reflective linear polarizer 26 24, or at the relative central pixel 28.1, to 20 degrees, and provides for limiting the angular spread of light rays either exiting a relatively-distal portion of the reflective linear polarizer 26, or at the edge pixel 28.2, to 9 degrees, so as to provide for relatively reducing or minimizing the amount of light 14.1 of the virtual image 104 that would otherwise propagate outside the bounds of a viewable portion of the exit pupil 108 ofthe near-eye display system 100 relative to a backlighting system that does not incorporate the combination of the extended light source 16, concave reflector 18, reflective linear quarterwave-plate 24, and polarizer 26.

[0055] The optical magnifier 102 provides for forming the virtual image 104 at a viewing distance 109 from the eye 106 that is comfortable for the user / viewer. The particular form of the optical magnifier 102 is not limiting, and for example, may include, but is not limited to, one or more of one or more of the following: a simple lens, a compound lens, a Fresnel lens, a catadioptric lens, a mirror, or any other arrangement of optical components that serve to form a virtual image 104 of the Liquid-Crystal Display (LCD) 12 / non-emissive image-display panel 12’.

[0056] For example, referring to FIGS. 6, 7a and 7b, in accordance with one set of embodiments, the near-eye display system 100 incorporates a first embodiment 110aof a catadioptric optical magnifier 110, 110a— also referred to as a "pancake lens’’ - that cooperates with a non-emissive image-display panel 12’ — for example, having a 56 millimeter diagonal dimension and 1.0 millimeter thick glass substrates - to form the virtual image 104 at a distance of approximately 2.5 meters from a typical position of the eye 106 of a user, with a nominal distance from the eye 106 to the first embodiment optical magnifier 102, 110, 110a, i.e. an eye relief distance 111, of 15 millimeters. For example, referring to FIGS. 7a and 7b, the first embodiment catadioptric optical magnifier 110, 110aincorporates afirst optical element 110.1 proximate the non-emissive image-display panel 12’ and a set of bonded second 110.2 and third 110.3 optical elements relatively proximate to the eye 106 of the user, with associated reflective and polarization elements at various surfaces typical of catadioptric optical magnifiers, wherein the third optical element 110.3 incorporates a slight aspheric curvature on the eye-proximate surface 110.3’ thereof. For example, referring to the FIG. 7b, in one set of embodiments, the LCD-proximate surface 110.1” of the first optical element 110.1 is 50 percent reflective, and the first embodiment catadioptric optical magnifier 110, 110afurther incorporates a quarterwave-plate 110.4 and a reflective linear polarizer 110.5 — for example, each of which is implemented as a corresponding film 110.4’, 110.5’ — between the second 110.2 and third 110.3 optical elements, with the quarter-wave-plate 110.4, 110.4’ abutting the second optical element 110.2, and with the reflective linear polarizer 110.5, 110.5’ sandwiched between and abutting the quarter-wave-plate 110.4, 110.4’ and the third optical element 110.3

[0057] Alternatively, referring to FIG. 8, in accordance with a second embodiment 110bof a catadioptric optical magnifier 110, 110b. the eye-proximate surface 110.3’ of the third optical element 110.3 is for example flat, i.e. not curved, for example, so as to provide for using arelatively-simple glass window that can more readily provide for a relatively-hard surface to reduce susceptibility to contact damage. Otherwise, the second-embodiment catadioptric optical magnifier 110, 110bis similar to the first-embodiment catadioptric optical magnifier 110, 110adescribed hereinabove.

[0058] FIG. 6 illustrates ray traces of fight 14.1 of the virtual image 104 from the locations of the relative central pixel 28.1 and first 28.2’ and second 28.2” edge pixels of the non- emissive image-display panel 12’ propagated through the catadioptric optical magnifier 110 - subject to the associated catadioptric reflections,— to an exit pupil 108 proximate to a location of the eye 106. These rays from each of the locations of the relative central 28.1 and edge 28.2’, 28.2” pixels have been constrained to form a bundle of light at the exit pupil 108 proximate to the location of the eye 106, wherein the exit pupil 108 of the near-eye display system 100 is defined herein as the real image of the extended light source 16 as formed by the optical magnifier 102, 110. In one set of embodiments, a viewable-without-vignetting portion 108’ of the exit pupil 108 is sufficiently large to provide light to the eye 106 without vignetting of the virtual image 104 either throughout the possible rotation angles of the eye 106 or responsive to moderate transverse and longitudinal misalignment of the eye 106 with the exit pupil 108, so as to provide for the user to be able to be either somewhat closer or somewhat farther from the exit pupil 108 in addition to having some lateral misalignment, without causing a disappearance of regions of the virtual image 104. For example, based on a general estimate of a relatively-large - for example, at least 90 degrees - field-ol'-view (FOV) near-eye display system and general human eye parameters in one set of embodiments, the diameter of the exit pupil 108 was selected to be 20 millimeters - but generally less than about 30 millimeters — to support such a non-vignetted environment based upon a general estimate of a relatively large field-of-view near-eye display system 100 and general human eye parameters, for example, for which the diameter of eye pupils typically range from 2 to 8 millimeters. Generally, a particular point on the exit pupil 108 will provide for viewing the associated virtual image 104 without vignetting if that point on the exit pupil 108 is responsive to the influence of every pixel 28 of the associated non-emissive image display panel 12, 12’.

[0059] The particular type of optical magnifier 102, 110, the various associated parameters thereof, and the size of the non-emissive image-display panel 12’ that have been illustrated are not intended to be limiting, but simply represent typical values and arrangements of some of modem near-eye-display-system products.

[0060] There are myriad variations of catadioptric optical magnifier designs, examples of which are disclosed in the following references that are incorporated by reference: Timothy L WONG, Zhisheng YUN, Gregg AMBUR. and Jo ETTER, ‘‘Folded optics with birefringent reflective polarizers”, in Digital Optical Technologies 2017 edited by Bernard C. Kress. Wolfgang Osten, and H. Paul Urbac, Proc, of SPIE Vol. 10335, 103350E, 2017’ and Qichao HOU, Dewen CHENG, Yang LI, Tian ZHANG, DanYang LI, Yilun HUANG, Hailong CHEN, Qiwei WANG, Weihong HOU, Tong YANG, and Yongtian WANG, “Stray light analysis and suppression method of a pancake virtual reality head-mounted display”, Optics Express, Vol. 30, No. 25, 5 Dec. 2022, pp. 44918-44932.

[0061] In accordance with one approach, the design of the backlighting subsystem 10 proceeds with the objective of configuring a compact arrangement of associated optical components providing light to the LCD non-emissive image-display panel 12, 12’ so that light 14.1 of the virtual image 104 emanating from any display pixel 28 substantially fills the viewable-without-vignetting portion 108’ of the exit pupil 108 that is viewable without vignetting, w ith substantially less light 14.1 of the virtual image 104 passing outside the bounds of that portion. For example, in one set of embodiments, less than 40 percent of the light 14.1 of the virtual image 104 passes outside - and therefore subject to vignetting - the viewable- without-vignetting portion 108’ of the exit pupil 108. Whereas the first surface 20 of the backlighting subsystem 10 if configured as a flat first-surface mirror might provide some benefit, more generally, a concave first-surface mirror 18.1 - specifically an off-axis first-surface mirror surface. — provides for a greater number of optical design parameters that can be optimized. Similarly, the second set of surfaces 22 could generally be implemented as a non-flat geometry for greater design flexibility. However, constraining the second set of surfaces 22 to being flat is beneficial given the substantial practical benefit for the second set of surfaces 22 to conform to a typically-flat Liquid-Crystal Display (LCD) 12, for example, so as to be prospectively configurable as part of an integral Liquid-Crystal Display (LCD) 12 component.

[0062] The particular configuration of the components of the backlighting subsystem 10 can be determined by using optical design software to optimize an associated merit function. In accordance with one approach, given the desired properties of the exit pupil 108 - e.g. 20 millimeters in diameter of the associated viewable-without-vignetting portion 108’ thereof- the associated optical rays are propagated in reverse from the exit pupil 108, through the optical magnifier 102, 110, through the LCD non-emissive image-display panel 12, 12’ that is treated as an optical-system aperture stop, and therefrom through the backlighting subsystem 10 so as to form an image of the exit pupil 108 at the location of the extended light source 16. By thereciprocity of optical rays, if the image of the ideal exit pupil 108 is formed at the location of the extended light source 16, then that exit pupil 108 can similarly be considered as the image of that extended light source 16 through the backlighting subsystem 10, the LCD non-emissive imagedisplay panel 12, 12’ and the optical magnifier 102, 110.

[0063] Such an optical design ultimately included the following: 1) an optimization merit function in accordance with well-established optical design practices to examine variations in the locations and angles of the extended light source 16 and concave first surface 18 relative to the flat second surface 22 at the LCD panel 12, 12’; 2) an appropriate weighting of the image quality formed at the location of the extended light source 16; variations in the optical parameters of an off-axis, aspherical, concave first-surface mirror 18.1; 3) appropriate constraints to ensure each component does not interfere with other components or the beam path; and 4) weighted parameters to minimize the overall size of the LCD backlight 16. The resulting merit function was then minimized in accordance with standard optical design practices, resulting in the particular design illustrated in FIGS. 4 and 6, for which, for example, the associated aspheric concave first-surface mirror 18.1 has an associated axis of symmetry 44 which is displaced from, and substantially parallel to, the axis of symmetry 102’ (i.e. optic axis 102’) of the optical magnifier 102, and which is substantially parallel to and displaced from an axis substantially perpendicular to, and centered about, the reflective linear polarizer 26, 26’, wherein ‘'substantially parallel” and “substantially perpendicular” are respectively intended to mean within 10 degrees of parallelism and perpendicularity, respectively. More particularly, modem optical design software provides for modeling the near-eye display system 100, including surfaces, glasses, image location, aperture stop and other details. The merit function is also somewhat automatically generated for an imaging system to minimize the ray deviations from ideal in the image plane and can be augmented by other constraints such as, for example, ideal locations and other physical properties of the components. In accordance with one approach, using this model, the near-eye display system 100 is optimized with respect to light propagated in reverse from the exit pupil 108 through the entire near-eye display system 100 to the extended light source 16. With the design of the optical magnifier 102 first optimized in advance without the backlighting subsystem 10, the light rays passing through any point on the LCD non-emissive image-display panel 12, 12’ by definition would have an angular extent that supports that exit pupil 108, and the geometric parameters of the extended light source 16 and the concave first-surface mirror 18.1 are optimized so as to form the best image of the exit pupil 108 at the extended light source 16 with light 14 reverse-propagating through the pre-defined optical magnifier 102. The modeling software provides for a merit function to be generated based on user inputs. For example, imagequality is determined by propagating field rays through the optical system and then evaluating where they hit the image plane, wherein an ideal image has all rays from each object point meet at a corresponding image point. The software allows one to customize how many rays originate from each point, whether the measurement is either Peak -to-V alley (PTV) or Root-Mean-Square (RMS), how much each field point is weighed (i.e. relative importance) and a number of other parameters. During optimization the software then propagates those rays from each object point to their respective ideal image point and then measures the deviation from that ideal point. A best image quality results from the minimization of either the PTV or RMS total deviation for each object / image point.

[0064] Whereas FIGS. 4 and 6 provides a reverse-propagated tracing of the rays from the exit pupil 108 back to the extended light source 16 in a first embodiment 100.1 of a near-eye display system 100, 100.1. the limited number of rays in FIGS. 4 and 6 do not clearly show the image formation properties in the image of the exit pupil 108 at the location of the extended light source 16. To better understand those properties, the same optimized design of FIGS. 4 and 6 is shown in FIGS. 9a-9d, but with many more rays propagated through the backlighting subsystem 10, which show s that each location of the 20 millimeter diameter exit pupil 108 does indeed form an image thereof at a corresponding location at the extended light source 16.

[0065] More particularly, referring to FIGS. 9a and 9c, light rays focused at a relatively- central point-location 108.1 of the exit pupil 108 are associated w ith a corresponding relatively central region 16.1 of the extended light source 16; referring to FIGS. 9a and 9b, light rays focused at an first, upper-edge point-location 108.2 of the exit pupil 108 are associated with a corresponding first upper-edge region 16.2 of the extended light source 16; and referring to FIGS. 9a and 9d, light rays focused at a second, lower-edge point-location 108.3 of the exit pupil 108 are associated w ith a corresponding second, lower-edge region 16.3 of the extended light source 16.

[0066] Although not all rays from a given location in the exit pupil 108 arrive at a corresponding single location in the extended light source 16, resulting in some amount of blur in the image of the exit pupil 108 formed at the location of the extended light source 16, it should be understood that all rays from each location of the ideal exit pupil 108 arrive within a confined area at the location of the extended light source 16. meaning that if an extended light source 16 were to completely fill that confined area while providing light along all rays arriving thereon, then the exit pupil 108 itself will be completely filled. Although all light 14 from such a extended light source 16 cannot be assumed to fall within the exit pupil 108, because of the imaging relationship between the extended light source 16 and the exit pupil 108, even with a poorlyformed exit pupil 108, light will still be confined to a substantially smaller region within and around the exit pupil 108 relative to light from a diffuse-backlit or emissive display that would otherwise flood the area of the eye 106.

[0067] It should be understood that the points formed in the exit pupil 108 by the illustrated light-ray tracings are not image formations of the LCD non-emissive image-display panel 12, 12’, but instead are points in the exit pupil 108 through which the user can view the virtual image 104 of the LCD non-emissive image-display panel 12, 12’, wherein the actual image of the LCD non-emissive image-display panel 12, 12’ is formed on the retina of the eye 106 of the user. Locations in the exit pupil 108 can be understood as locations of bundles of light 14 that support that viewing, wherein at the exit pupil 108 is just a blurry real image of the associated extended light source 16, and the exit pupil 108 is a region of space where the entire virtual image 104 becomes visible to an eye 106 located thereat. This image of the extended light source 16 at the exit pupil 108 does not at all need to be well formed, but instead, provides for a bundle of light at the eye 106 of the user that is large enough for the full virtual image 104 to be seen without vignetting and, preferably, without a variation in image intensity7or uniformity responsive to a rotation of the eye 106. The exit pupil 108 therefore becomes a blurry zone of light 14 through which the virtual image 104 is viewed. Diffractive scattering will provide for further expanding and blending the light 14 so as to provide for a more uniformly illuminated and sufficiently sized exit pupil 108. Accordingly, the exit pupil 108 is a transverse region of space that is illuminated by the light 14 from the extended light source 16, where in the size and shape thereof are responsive to the transverse size and shape / distribution of the extended light source 16, the imaging properties of the concave reflector 18, 18’, the imaging properties of the associated optical magnifier 102, and diffractive effects.

[0068] Accordingly, FIGS. 9a-9d illustrate that there is a region of limited extent within the extended light source 16 that fully fills the 20 millimeter diameter exit pupil 108. Furthermore, it can be assumed that diffractive scattering will somewhat broaden the exit pupil 108 filled by that extended light source 16, so that region of the extended light source 16 can be reduced in size while still filling the 20 millimeter diameter exit pupil 108, depending on the degree of diffractive scattering.

[0069] FIGS. 10a- lOd and lla-lld apply the same design of the backlighting subsystem 10 as in FIG. 4, in respective second- 100.2 and third- 100.3 embodiment near-eye-display systems 100, but with respective 15 millimeter and 10 millimeter diameter exit pupils 108 respectively, so as to illustrate the resulting corresponding reduction in the size of the associated extended light source 16 that will provide for filling those smaller exit pupils 108. Thedetermination of the minimum size of the extended light source 16 for a correspondingly minimum size of the backlighting subsystem 10 will depend upon the degree to which diffractive scattering can be relied upon to broaden the exit pupil 108.

[0070] More particularly, referring to FIGS. 10a and 10c, light rays focused at a relatively- central point-location 108.1 of the exit pupil 108 are associated with a corresponding relatively central region 16.1 of the extended light source 16; referring to FIGS. 10a and 10b, light rays focused at a first, upper-edge point-location 108.2 of the exit pupil 108 are associated with a corresponding first edge region 16.2 of the extended light source 16; and referring to FIGS. 10a and lOd, light rays focused at a second, lower-edge point-location 108.3 of the exit pupil 108 are associated with a corresponding second edge region 16.3 of the extended light source 16.

[0071] Furthermore, referring to FIGS. Ila and 11c, light rays focused at a relatively-central point-location 108.1 of the exit pupil 108 are associated with a corresponding relatively central region 16.1 of the extended light source 16; referring to FIGS. Ila and 11b. light rays focused at a first, upper-edge point-location 108.2 of the exit pupil 108 are associated with a corresponding first edge region 16.2 of the extended light source 16; and referring to FIGS. Ila and lid, light rays focused at a second, lower-edge point-location 108.3 of the exit pupil 108 are associated with a corresponding second edge region 16.3 of the extended light source 16.

[0072] In each of FIGS. 1, 4, 6, 9a-9d, lOa-lOd, lla-lld, 12a-b, and 13a-b of the corresponding associated near-eye display systems 100, 100.1, 100.2, 100.3, the extended light source 16 is extended along a local y direction so as to provide for the resulting light 14, 14.1 of the virtual image 104 to be distributed in a vertical Y direction at the exit pupil 108 so as to provide for viewing thereof by the eye 106 over a range of up-down rotations of the eye 106 so as to provide for viewing the vertical extent of the virtual image 104. Similarly, referring also to FIGS. 12a-b, 13a-b, and 14a-d, the extended light source 16 is also extended along a local x direction so as to also provide for the resulting light 14, 14.1 of the virtual image 104 to be distributed in a lateral X direction at the exit pupil 108 so as to provide for viewing thereof by the eye 106 over a range of left-right rotations of the eye 106 so as to provide for viewing the horizontal extent of the virtual image 104.

[0073] More particularly, referring to FIGS. 14a and 14c, light rays focused at a relatively- central point-location 108.1 of the exit pupil 108 are associated with a corresponding relatively central region 16.1 of the extended light source 16; referring to FIGS. 14a and 14b, light rays focused at a first left-edge point-location 108.4 of the exit pupil 108 are associated with a corresponding fourth region 16.4 of the extended light source 16; and referring to FIGS. 14aand 14d, light rays focused at a second right-edge point-location 108.5 of the exit pupil 108 are associated with a corresponding fifth region 16.5 of the extended light source 16.

[0074] Referring again to FIG. 1, generally, the near-eye display system 100 comprises a combination of a real imaging subsystem 112 in cooperation with a corresponding associated virtual imaging subsystem 114, each of which utilizes the same optical magnifier 102, wherein the real imaging subsystem 112 utilizes the optical magnifier 102 to form a real image 112’ of the extended light source 16 at the exit pupil 108, and the virtual imaging subsystem 116 utilizes the optical magnifier 102 to form a virtual image 104 of the LCD non-emissive image display panel 12, 12’ at a viewing distance 109 from the eye 106 that is comfortable for the user / viewer to view. An exit pupil is defined as an associated aperture stop image as would be seen if viewed from the final image-plane (Warren J. Smith, Modern Optical Engineering, 3e. McGraw-Hil, 2000, p. 142). Accordingly, for the extended light source 16 acting as the aperture stop of the real imaging subsystem 112, what is referred to herein as the exit pupil 108 is the exit pupil of the real imaging subsystem 112, whereas the virtual imaging subsystem 114 has a separate and distinct associated exit pupil at the location of the virtual image 104, with that exit pupil being an image of the LCD non-emissive image display panel 12, 12’ acting as the aperture stop of the virtual imaging subsystem 114.

[0075] Accordingly, the real imaging subsystem 112 provides for collecting the light 14.1 of the virtual image 104 for viewing by the eye 106, which views the virtual image 104 formed by the optical magnifier 102 from the light 14.1 thereof, at a viewing distance 109 from the exit pupil 108 that provides for the user / viewer to comfortably view the virtual image 104. Referring to FIGS. 12a-b and 13a-b. the extended light source 16 provides for emitting light from an extended region in local x-y space for which the associated resulting real image 112’ of the extended light source 16 at the exit pupil 108 spans a corresponding region in the X-Y space thereof within which the light 14.1 of the virtual image 104 is distributed so as to provide for the virtual image 104 to be seen over a range of possible rotations and translations of an eye 106 located at the eye location 116 of the near-eye display system 100, i.e. the location of the eye 106 for which the associated eye pupil 118 is located sufficiently proximate to the exit pupil 108 so as to be able to receive the light 14.1 of the virtual image 104 - and of the associated real image 112’ of the extended light source 16 — over a range of rotations and translations of the eye 106 when located thereat, so that the user / viewer can view the virtual image 104.

[0076] Referring also to FIGS. 15a-d — illustrating horizonal cross sections of the LCD non- emissive image display panel 12, 12’, optical magnifier 102, 110, and associated exit pupil 108 — a given location within the exit pupil 108 can be viewed without vignetting for all feasiblerotations of the eye 106 if that location is responsive to light 14, 14.1 from every LCD pixel 28 of the LCD non-emissive image display panel 12, 12’. Accordingly, for each of FIGS. 15a-d, the viewable-without-vignetting portion 108’ of the exit pupil 108 that can be viewed without vignetting for all feasible rotations of the eye 106 receives light 14, 14.1 from each of the pixel locations 12.1, 12.2, 12.3, and 12.4 respectively indicated in FIGS. 15a-d, respectively. More particularly, in FIG. 15a, for a left-most pixel location 12.1, locations on the exit pupil 108 to the left and far right of the viewable-without-vignetting portion 108’ would be subject to vignetting; in FIG. 15b, for a mid-left pixel location 12.2, locations on the exit pupil 108 to the far left of the viewable-without-vignetting portion 108’ would be subject to vignetting; in FIG. 15c, for a central pixel location 12.3, locations on the exit pupil 108 to the far left and far right of the viewable-without-vignetting portion 108’ would be subject to vignetting; and in FIG. 15d, for a right-most pixel location 12.4. locations on the exit pupil 108 to the right and far left of the viewable-without-vignetting portion 108’ would be subject to vignetting.

[0077] In one set of embodiments, the extended light source 16 and the concave reflector 18 are configured so that at least 60 percent of the light 14, 14.1 from the extended light source 16 passes through the associated viewable or viewable-without-vignetting portion 108’ of the exit pupil 108, and are configured so that the associated viewable-without-vignetting portion 108’ of the exit pupil 108 is viewable over a full range of up-down and left-right rotations of an eye 106 located at the eye location 116, for at least one user / viewer, so that the associated virtual image 104 is fully viewable without vignetting from that eye location 116 by that user / viewer. For example, in one set of embodiments the viewable-without- vignetting portion 108’ of the exit pupil 108 does not exceed about 30 millimeters in each of vertical and horizontal extent.

[0078] Referring again to FIGS. 12a and 13a - associated with FIGS. 4, 6, 9a-d, lOa-d, 1 lari, and 14a-d, -- for a substantially-circular exit pupil 108, 108cwith an corresponding substantially-circular viewable-without-vignetting portion 108’, 108cthereof, the corresponding extended light source 16, 16chas an associated elliptical shape as a result of the geometry thereof and of the concave reflector 18. Similarly, referring again to FIGS. 12b and 13b - associated with FIGS. 17-19, — for a substantially-rectangular exit pupil 108, 108Rwith an corresponding substantially-rectangular viewable-without-vignetting portion 108’, 108R’ thereof, the corresponding extended light source 16, 16Ralso has an associated rectangular shape, but of wider aspect ratio as a result of the geometry thereof and of the concave reflector 18.

[0079] Referring again to FIG. 1, in accordance with one set of embodiments an eye- proximate surface 120 of the optical magnifier 102 is separated from the exit pupil 108 by atleast 8 millimeters, for example, so as to provide a sufficiently -large eye-relief distance 111 so as to provide clearance for an eyelash 122 of the eye 106.

[0080] Referring to FIGS. 16-19, a binocular pair 100’ of fourth-embodiment near-eye display systems 100, 100.4 enclosed within an associated housing 124 is illustrated in FIG. 16 in operative association with the head of a user / viewer 126. Referring to FIGS. 17 and 18, each of the fourth-embodiment near-eye display systems 100, 100.4 incorporates a rectangular extended light source 16, 16Rcomprising a rectangular array of a plurality of Light-Emitting Diodes (LED’s) 16’ that provide for illuminating a concave reflector 18 as described hereinabove in accordance with FIG. 2. Also in accordance with FIG. 2, the fourth-embodiment near-eye display systems 100, 100.4 further incorporates a quarter-wave-plate 24, 24’ and a reflective linear polarizer 26, 26’, that in cooperation with the extended light source 16, 16Rand concave reflector 18, provide for illuminating an associated LCD non-emissive image display panel 12, 12’. as also described hereinabove in accordance with FIG. 2, the latter of which, in accordance with FIG. 1 hereinabove, receives electronic image content 30 of a virtual image 104 from an associated source 32, which is then imparted by the LCD non-emissive image display panel 12, 12’ to the light 14, 14.1 thereof, the latter of which is then processed by an optical magnifier 102, for example, a third embodiment 110cof a catadioptric optical magnifier 110, 110cthat is similar to the second-embodiment catadioptric optical magnifier 110, 110bdescribed hereinabove.

[0081] Referring to FIGS. 18 and 19, the third-embodiment catadioptric optical magnifier 110, 110cforms — at the exit pupil 108 — a real image 112’ of the extended light source 16, 16R, of which five exit-pupil points 108.1, 108.6, 108.7, 108.8, and 108.9 are illustrated in FIG. 18, which also illustrates rays of light 14.1 of the virtual image 104 that propagate thereto from the extended light source 16, 16R, following reflection from the concave reflector 18 and the reflective linear polarizer 26, and subsequent propagation through the reflective linear polarizer 26 and the third-embodiment catadioptric optical magnifier 110, 110c, with the light rays illustrated in FIG. 18 being traced from their focus at the five exit-pupil points 108.1, 108.6, 108.7, 108.8, and 108.9 back to five corresponding respective loci 16.1, 16.6, 16.7, 16.8, and 16.9 of points of the associated extended light source 16, 16R, further illustrating the many-to-one correspondence between points in the space of the extended light source 16 and corresponding points in the exit pupil 108.

[0082] Whereas the backlighting subsystem 10 does not form an ideal image at the exit pupil 108, the fact that such an image is blurry and will be additionally blended by diffractive scatteringfrom the LCD non-emissive image-display panel 12, 12’ means that any localized change in intensity as a function of spatial location within the extended light source 16 will be blended to make a more uniformly illuminated exit pupil 108. Such blurring and blending therefore provides for accommodating spatial structure in the illumination profile of the extended light source 16, such as may be caused by using an array of discrete light sources or a microlens array in front of such light sources, which provides for additional design flexibility in utilizing a extended light source 16 with as much directionality as possible to minimize the amount of light falling outside of the viewable portion of the exit pupil 108, while maximizing the amount of light falling within the viewable portion of the exit pupil 108. For example, such directionality may be provided by, inter alia, either using lensing in front of the extended light source 16, or by deploying the extended light source 16 on a curv ed surface.

[0083] Ideally, the light leaving each pixel 28 of a non-emissive image-display panel 12, 12’ would have a relatively -narrow, forward-directed angle, that in cooperation with the optical magnifier 102 provides for fdling the portion of the exit pupil 108 that is viewable - either with or without vignetting, — and not extending substantially therebeyond. Part of the simplicity of developing the backlighting subsystem 10 for an ideal rather than specific optical magnifier 102 is that it would likely work with any optical magnifier 102 as long as the full angles leaving each pixel 28 fully enclose the associated pixel angles associated with the viewable portion of the exit pupil 108, i.e. so as to provide for filling that portion of the exit pupil 108.

[0084] Although a microlens array proximate the non-emissive image-display panel 12’ might otherwise be considered to better collimate and direct the light from each pixel 28 of a non- emissive image-display panel 12, 12’, such a microlens array might be susceptible to a) displaying artifacts in the image, b) not providing good directionality for pixel structures having non-point profiles, and c) further creating an additional diffractive scattering mechanism because each microlens would need to be very small to support a high-resolution display panel.

[0085] Accordingly, the backlighting subsystem 10 can provide for an associated near-eye display system 100 for which a substantially greater portion of light 14 from the extended light source 16 fills the viewable portion of the exit pupil 108 than would otherwise occur without the backlighting subsystem 10, thereby requiring relatively less electrical power for that extended light source 16 than would be required by emissive or diffuse-backlit displays because of the light 14 therefrom being used more efficiently. Furthermore, because there is substantially less light 14 in total passing through the optical magnifier 102, 110, and substantially less light 14 reaching the user’s face, there is a corresponding relatively significant decrease in the amount of scatteredlight that reaches the eye pupil 118 of the user, which provides for dramatically increasing the contrast in the virtual image 104.

[0086] Referring again to FIG. 1, the near-eye display system 100 may further incorporate an extended light-source controller 128 so as to provide for controlling the relative intensities of different light emitters 16’, or light-emitting portions, of the extended light source 16, 16’, for example, so as to provide for a substantially-uniform intensity of the virtual image 104 as perceived by the user / viewer 126. For example, for at least 60 percent of the light 14.1 of the virtual image 104 propagating to the viewable or viewable-without-vignetting portion 108’ of the exit pupil 108, different light emitters 16’, or light-emitting portions of the extended light source 16, 16’ might contribute relatively different amounts of light 14, 14.1 to the viewable- without-vignetting portion 108’ of the exit pupil 108, which can be compensated for by relatively increasing the intensity of light emitters 16’, or light-emitting portions of the extended light source 16, 16’ that would - without compensation - contribute relatively less light 14, 14.1 to the viewable-without-vignetting portion 108’ of the exit pupil 108, and / or relatively decreasing the intensity of light emitters 16’, or light-emitting portions of the extended light source 16, 16’ that would - without compensation — contribute relatively more light 14, 14.1 to the viewable-without-vignetting portion 108’ of the exit pupil 108. For example, the extended- light-source controller 128 can be implemented by either a fixed proportioning of light emitted by the light emitters 16’ or light-emitting portions of the extended light source 16, 16’; or by actively controlling the light emitters 16’, or light-emitting portions of the extended light source 16, 16’ responsive to a detection of light 14, 14.1 reflected or scattered from the eye 106 of the user / viewer 126 in relation to a knowledge of the intensity of the corresponding electronic image content 30. For example, a fixed proportioning of the light emitted by the light emitters 16’ or light-emitting portions of the extended light source 16, 16’ can be determined responsive to a measurements - either with instruments or as perceived by a nominal user / viewer 126 — of the intensity of the light 14, 14.1 at a nominal location of the eye pupil 118 within the eye location 116 for each controllable light emitter 16’ or light-emitting portions of the extended light source 16, 16’. For example, in one set of embodiments, the extended light source 16, 16’ is configured, adjusted, or controlled to provide for less than a 20 percent variation in brightness over the viewable-without-vignetting portion 108’ of the exit pupil 108, or more generally, over the viewable portion of the exit pupil 108 that can be seen by an eye 106 located at an eye location 116, over a feasible range of rotations of the eye 106.

[0087] For a given optical magnifier 102 that provides for creating a desired virtual image104 of a non-emissive image-display panel 12 through a portion of the exit pupil 108 that isviewable without vignetting, the backlighting subsystem 10 provides for a relatively low cost, relatively compact, and relatively simple optical configuration to provide light 14 through each LCD pixel 28 that fully fills the desired portion of the exit pupil 108 through the optical magnifier 102 while substantially reducing the amount of light 14 that would otherwise pass outside of the viewable portion of the exit pupil 108 absent the backlighting subsystem 10.

[0088] The backlighting subsystem 10 incorporates a cavity 46 bounded by the extended light source 16, the concave first-surface mirror 18.1 and the second set of surfaces 22 associated with the quarter-wave-plate 24, and reflective linear polarizer 26. The cavity 46 may be either air-filled, or may be fdled with a transparent optical material such as acrylic with low birefringence, or the backlighting subsystem 10 may be constructed as an integral, solid element with a reflective coating on a first surface thereof to provide for the concave first-surface mirror 18.1, and for the second set of surfaces 22 associated with the quarter-wave-plate 24, and reflective linear polarizer 26. either applied to, or abutting, an opposing second surface. Either the solid-filed cavity 46 or the integral-solid-element backlighting subsystem 10 would provide for bonding the backlighting subsystem 10 directly to the LCD non-emissive imagedisplay panel 12, 12’, so as to provide for excellent positional registration and also mitigate against the accumulation of dust that may otherwise enter an air-filled cavity 46.

[0089] It should be understood that the LCD non-emissive image-display panel 12, 12’ could be implemented as either a transmissive amplitude-modulating display panel as describe above, or, alternatively, as reflective amplitude-modulating display panel, wherein the optical magnifier is designed to provide a sufficient space between the display-proximate surface and the display to accommodate the backlight structures in reverse for illuminating the display panel from the front, and wherein the concave reflector is now only partially reflective to allow light reflectively- modulated from the display panel to pass through the concave reflector into the optical magnifier.

[0090] Light 14”” leaving each pixel location of a LCD non-emissive image display panel 12, 12’ having a relatively narrow, forward-directed angle in accordance with the properties of the associated optical magnifier 102 provides for that optical magnifier 102 to primarily fill the viewable portion of the exit pupil 108 located proximate to an eye location 116. Given an optical magnifier 102 optimized for creating the desired virtual image 104 of a LCD non-emissive image display panel 12, 12’ through a desired viewable portion of the exit pupil 108, the associated extended light source 16 is arranged in a relatively low-cost, compact, relatively simple optical configuration to provide light 14”” through each of the LCD pixels 28 that fully fills the desired viewable portion of the exit pupil 108 through the optical magnifier 102 whilesubstantially reducing the amount of light 14”” passing outside that viewable portion of the exit pupil 108.

[0091] Referring to FIG. 21, as disclosed by S. Kelly in “Projection LCD backlighting for improved VR display contrast through a pancake lens while using much less power’; Proc. Of SPIE, Vol. 13414, 13414OG, doi.org / 10. 1117 / 12.3042169, — which is incorporated herein by reference in its entirety, — a pair of commercially-available 56 millimeter RGB LCD non- emissive image display panels 12, 12’ of 2160 x 2160 resolution were used in a binocular 3D- printed demonstration near-eye display system 100 having a fixed, 70 millimeter interpupillary distance, as constrained by the associated LCD driver board, wherein each of the left and nght sides used the same type of off-the-shelf pancake lens to form an associated virtual image. Whereas the included diffuse backlight was used as the light source to illuminate the left RGB LCD non- emissive image display panels 12, 12’, for the right side, the RGB LCD non-emissive image display panels 12, 12’ was disassembled to provide for light 14”” to transmit therethrough, and the back of the right-side RGB LCD non-emissive image display panel 12, 12’ was fitted with a film-type reflective linear polarizer 26, 26’ and film-type quarter-wave-plate 24, 24’, each oriented so as to provide for the linearly polarized light 14”” to pass through the RGB LCD non- emissive image display panel 12, 12’ following a the second reflection from an associated optimized concave first-surface mirror 18, 18.1 that was injection-molded from ABS using a CNC -generated, then hand-polished, mold, and then chrome plated to generate a reflective surface. Referring to FIG. 20, for the right side, the associated extended light source 16 comprised an array of seventeen (17) Light-Emitting Diodes (LED’s) 16’, each having a curved lens and each with a power rating of 20 milliwatts, oriented relative to the RGB LCD non-emissive image display panel 12, 12’ as illustrated in FIG. 6. The extended light source 16 was further covered with a film-based transmissive linear polarizer 38 and a film-based quarter-wave plate 40 so as to produce circularly polarized light.

[0092] Both the left and right RGB LCD non-emissive image display panels 12, 12’, were driven with identical test pattern images. A digital camera was used to produce the zoomed-in images of FIG. 21 through each corresponding pancake lens, wherein the left side image of FIG. 21 is a virtual image 201 of the left-side RGB LCD non-emissive image display panel 12, 12’ illuminated by the commercial diffuse backlight that had been included with the commercial RGB LCD non-emissive image display panel 12, 12’, and the right side image of FIG. 21 is a virtual image 104 of the right-side RGB LCD non-emissive image display panel 12, 12’ adapted as part of an associated near-eye display system 100, illuminated by the extended light source 16 illustrated in FIG. 20 covered with a film-based transmissive linear polarizer 38 and a film-based quarter-wave plate 40, in cooperation with the custom concave first-surface mirror 18, 18.1, the film-type reflective linear polarizer 26, 26’, and the film-type quarter-wave-plate 24, 24’ . The distortion in the right image was due to residual dust on the added polarization films. The left image was slightly modified to account for moderate scattering from the face area around the eye — which camera modifications could not easily replicate - so that the resulting images are proper representations of visual results, which clearly show the contrast enhancement when using the associated backlighting subsystem 10. The size of the associated extended light source 16 was sufficient to provide a sufficiently -large exit pupil 108 so as to provide for comfortable, unvignetted viewing throughout the entire field of view. As expected, positioning one’s eye away from the optical axis of the near-eye display system 100 — thereby displacing the eye pupil 118 relative to the viewable portion of the exit pupil 108 — resulted in a very' significant fall-off in visual brightness, which is an added benefit because such a displacement necessarily results in significantly aberrated image quality, with it being preferable to require the user’s eye pupil 118 to be within the viewable portion of the exit pupil 108 in order to be able to see the best quality image. These results were achieved without brightness modifications. Whereas the power specified for the left-side diffusive LCD backlight was over 1000 milliwatts, in comparison, the seventeen (17) 20 milliwatt LED’s provide for a power reduction of approximately 65 percent.

[0093] In accordance with one set of embodiments, a backlighting subsystem 10 for use with a non-emissive image-display panel 12, 12’ comprises: an extended light source 16, a concave reflector 18, 18.1, a quarter-wave-plate 24, 24’, and a reflective linear polarizer 26, 26’, wherein the extended light source 16 provides for generating light 14 and is oriented so that the light 14 impinges directly upon a reflective surface 20 of the concave reflector 18, 18.1. the quarter-wave-plate 24, 24’ is located and oriented so as to receive the light 14, 14’” reflected from the concave reflector 18, 18.1, the reflective linear polarizer 26, 26’ is located and oriented to receive the light 14, 14’” reflected from the concave reflector 18, 18.1 and transmitted through the quarter-wave-plate 24, 24’, the reflective linear polarizer 26, 26’ provides for reflecting the light 14’ reflected from the concave reflector 18, 18.1 and transmitted through the quarter- wave-plate 24, 24’ having a first polarization direction, back through the quarter-wave-plate 24, 24’ to be reflected from the concave reflector 18, 18.1, the reflective linear polarizer 26, 26’ provides for transmitting the light 14”” reflected from the concave reflector 18, 18.1 and transmitted through the quarter-wave-plate 24, 24’ having a second polarization direction, wherein the second polarization direction is orthogonal to the first polarization direction, and the quarter-wave-plate 24, 24’ provides for converting linearly-polarized light 14’ to circularly- polarized light 14”, and vice versa 14’”, 14””.

[0094] Furthermore, a method of illuminating a non-emissive image-display panel 12, 12’, comprises: generating light 14 and directing the light 14 at a concave reflector 18, 18.1; reflecting the light 14, 14” from the concave reflector 18, 18.1; passing the light 14, 14”’ reflected from the concave reflector 18, 18.1 through a quarter-wave-plate 24, 24’ that converts circularly- polarized light 14’” to linearly-polarized light 14”” and vise versa 14’, 14”, for light 14, 14’ passed through the quarter-wave-plate 24, 24’ having a first polarization, reflecting with a reflective linear polarizer 26, 26’ the light 14’ passed through the quarter-wave-plate 24, 24’ having the first polarization, and passing the light 14’ reflected by the reflective linear polarizer 26, 26’ through the quarter-wave-plate 24, 24’ for subsequent reflection by the concave reflector 18, 18.1; and for light 14”” passed through the quarter-wave-plate 24, 24’ having a second polarization that is orthogonal to the first polarization, passing the light 14”” having the second polarization through the reflective linear polarizer 26, 26’.

[0095] Such a lighting solution would not be practicable with an emissive-type display. Accordingly, it is conceivable that the net contrast of a near-eye display system 100 using the backlighting subsystem 10 may approach, or may even exceed, the net contrast of a near-eye display system incorporating an emissive display even if the emissive display itself provides higher native contrast.

[0096] Referring to FIG. 22, for purposes of comparison, a near-eye display system 200 incorporates an array of light-emitting pixels 202 as an emissive image-display panel 204, each light-emitting pixel 202’ of which - for example, implemented with an Organic Light-Emitting Diode (OLED) — corresponds to an image pixel 205’ of the associated virtual image 205, wherein the near-eye display system 200 otherwise incorporates a catadioptric optical magnifier 102, 206 that is substantially the same as the above-described catadioptric optical magnifier 110 illustrated in FIGS. 6, 7a and 7b. The radiation from each light-emitting pixel 202’ is emitted toward the magnifier into such a large solid angle that much of that light never reaches the eye 106 of the user. Even considering eye rotation in association with a relatively large field-of-view (FOV) near-eye display system 200, the vast majority of light would strike the user’s face around the eye area while completely missing the eye 106, which not only wastes a substantial amount of power, but is also associated with a decrease in the overall image contrast as a result of stray reflections of that wasted light within the optical magnifier 102 in addition to light scattered or reflected from the user’s face back into the optical magnifier 102.

[0097] Referring to FIGS. 23a and 23b - illustrating light-ray traces from respective relatively central 202.1’ and edge 202.2’ light-emitting pixels, - the range of angles of lightrays that reach a viewable portion of the exit pupil 108 at the eye 106 are respectivelyapproximately 20 degrees for the relatively central light-emitting pixel 202.1’, and 9 degrees for the edge light-emitting pixel 202.2’. Accordingly, any light 14 exiting those relatively central 202.1’ and edge 202.2’ light-emitting pixels beyond these respective angular ranges will not pass through the viewable portion of the exit pupil 108 and would therefore be both a waste of power and a source of light scattering.

[0098] A light-emitting pixel 202’ typically emits light 14 with decreasing intensity with respect to the angle off normal to the surface of the emissive image-display panel 204, wherein the normalized radiation intensity as a function of angle from normal can be approximated as Lambertian. Referring to FIG. 24, a normalized two-dimensional Lambertian plot is overlayed with full emission angles of 9 and 20 degrees that corresponding to the amount of light from each of the respective edge 202.2’ and relatively central 202.1’ light-emitting pixels that could fill the viewable portion of the exit pupil 108, which shows that well over half the light 14 from an average pixel location would not pass through the exit pupil 108. Applying this plot to both directions, i.e. horizontal and vertical, the corresponding resulting three-dimensional solid angle comparison suggests that over 80% of the light from an emissive image-display panel 204 would not directly reach the exit pupil 108, but instead would provide for scattering and reflection either within the near-eye display system 200 or from the user's face, and then back into the near-eye display system 200, ultimately partially scattering into the exit pupil 108, resulting in a reduction in contrast.

[0099] The behavior illustrated in FIGS. 22-24 would similarly result if the emissive imagedisplay panel 204 was replaced with as diffuse-backlit transmissive image pixel, for example, a Liquid Crystal Display (LCD) that was illuminated by a diffuse light source having a radiation profde for each backlit transmissive pixel similar to that illustrated in FIG. 24. Diffuse-backlit LCD pixels also typically emit light with decreasing intensity as the angle from the LCD surface normal increases. While LCD backlights further include Brightness Enhancement Films (BEF) to concentrate light more into a forward angle, any diffractive scattering through a high resolution LCD panel effectively broadens that angle, so that the normalized radiation intensity as a function of angle from normal from a backlit LCD pixels can also be approximated as Lambertian.

[0100] The highly directional nature of the backlighting subsystem 10 therefore provides for concentrating much more of the light 14 from the extended light source 16 through the desired viewable portion of the exit pupil 108, than with a light source alone directly illuminating the associated Liquid-Crystal Display (LCD) 12. While there may be an imperfect imaging relationship between the extended light source 16 and the exit pupil 108, even a blurry image of that extended light source 16 at the exit pupil 108 will significantly increase the ratio of light 14through the viewalbe portion of the exit pupil 108 relative to that which falls outside the viewable portion of the exit pupil 108. For example, whereas approximately 80% of the light 14 from an emissive image-display panel 204 would fall outside of an associated 20 millimeter diameter exit pupil 108, it is estimated that for some embodiments, less than 20% of the light 14 from the extended light source 16 of the above-described backlighting subsystem 10 will extend beyond the associated viewable portion of the exit pupil 108.

[0101] A backlighting system for use with a non-emissive image-display panel incorporates an extended light source; a concave reflector; a first quarter-wave plate; and a reflective linear polarizer, wherein the extended light source provides for generating light and is oriented so that the light impinges directly upon a reflective surface of the concave reflector; the first quarter-wave plate is located and oriented so as to receive the light reflected from the concave reflector; the reflective linear polarizer is located and oriented to receive the light reflected from the concave reflector and transmitted through the first quarter-wave plate; the reflective linear polarizer provides for reflecting the light reflected from the concave reflector and transmitted through the first quarter-wave plate having a first polarization direction, back through the first quarter-wave plate to be reflected from the concave reflector; the reflective linear polarizer provides for transmitting the light reflected from the concave reflector and transmitted through the first quarterwave plate having a second polarization direction, wherein the second polarization direction is orthogonal to the first polarization direction; and the first quarter-wave plate provides for converting linearly -polarized light to circularly-polarized light, and vice versa. Further, in any feasible combination: the extended light source may incorporate a plurality of light-emitting diodes; the extended light source may incorporate a plurality of localized-light-sources, and may further incorporate in association with at least one localized-light-source of the plurality of localized-light sources, a corresponding lens that provides for concentrating and directing the light from the at least one localized-light-source of the plurality of localized-light-sources; the extended light source may span a two-dimensional region; the concave reflector may incorporate an optical axis of symmetry' that is parallel to and displaced from an axis substantially perpendicular to and centered about the reflective linear polarizer; the concave reflector may incorporate a reflective first surface; a cavity' between the concave reflector and the first quarter-wave plate may incorporate an optically-transparent solid material; the concave reflector may be configured in cooperation with the extended light source, the first quarter-wave plate, and the reflective linear polarizer so that an angular spread of the light exiting a relatively distal portion of the reflective linear polarizer may be within 9 degrees; the first quarter-wave plate may be tuned for operation at a wavelength within a mid-green range of wavelengths; the first quarter-wave plate may be flat;the reflective linear polarizer may be flat; , the backlighting system may further incorporate: a transmissive linear polarizer located between the extended light source and the concave reflector; and a second quarter-wave plate located between the transmissive linear polarizer and the reflective linear polarizer, the second quarter-wave plate may be tuned for operation at a wavelength within a mid-green range of wavelengths; the backlighting system may further incorporate a reflective or absorptive mask that provides for blocking a portion of the light generated by the extended light source that would otherwise pass through or around the reflective linear polarizer following reflection from the concave reflector; the concave reflector may be configured in cooperation with the extended light source, the first quarter-wave plate, and the reflective linear polarizer so that an angular spread of the light exiting the reflective linear polarizer is within 20 degrees; the backlighting system may further incorporate the non-emissive imagedisplay panel, wherein the non-emissive image-display panel may be located so as to receive the light that passes through the reflective linear polarizer, and the non-emissive image-display panel provides modulating and transmitting therethrough the light passing through the reflective linear polarizer; the non-emissive image-display panel may incorporate the reflective linear polarizer; the reflective linear polarizer may be bonded to the non-emissive image-display panel; the non- emissive image-display panel may incorporate the first quarter-wave plate; the first quarter-wave plate may be bonded to the reflective linear polarizer; the backlighting system may further incorporate an optical magnifier located between the non-emissive image-display panel and an eye location, wherein the optical magnifier provides for receiving and processing therebetween the light from the non-emissive image-display panel, the optical magnifier in cooperation with the extended light source define an exit pupil, the exit pupil is proximate to the eye location for viewing a virtual image of the non-emissive image-display panel by an eye when the eye is at the eye location, and the virtual image is formed by the optical magnifier at a viewing distance that is displaced from the exit pupil; the optical magnifier forms a real image of the extended light source at the exit pupil; the backlighting system may be configured so that at least 60 percent of the light from the extended light source passes through a viewable portion of the exit pupil that is viewable by the eye when the eye is at the eye location; for at least a portion of the exit pupil, the light at each location of the portion of the exit pupil may be responsive to every pixel of the non-emissive image-display panel illuminated by the extended light source, wherein the backlighting system may be configured so that at least 60 percent of the light from the extended light source passes through the portion of the exit pupil, for the eye located at the eye location, the portion of the exit pupil may be located and sized so as to provide for viewing by the eye of the portion of the exit pupil over a full range of rotations of the eye, a maximum of a vertical extent of the portion of theexit pupil and a horizontal extent of the portion of the exit pupil may not exceed 30 millimeters, and the extended light source may incorporate a plurality of independently-controllable light emitters, and a brightness of at least one of the plurality of independently-controllable light emitters may be adjusted or controlled relative to at least one other of the plurality of independently-controllable light emitters so that both the at least one of the plurality of independently-controllable light emitters and the at least one other of the plurality of independently-controllable light emitters each exhibit a substantially uniform brightness in the portion of the exit pupil; the optical magnifier may incorporate a catadioptric optical magnifier, wherein an eye-proximate surface of the catadioptric optical magnifier may be either curved or flat; and an eye-proximate surface of the optical magnifier may be located at least 8 millimeters from the exit pupil.

[0102] A method of illuminating a non-emissive image-display panel comprises: generating light over an extended region using an extended light source; directing the light at a concave reflector; reflecting the light from the concave reflector; passing the light reflected from the concave reflector through a first quarter-wave plate that converts circularly-polarized light to linearly-polarized light and vise versa; for the light passed through the first quarter-wave plate having a first polarization, reflecting with a reflective linear polarizer the light passed through the first quarter-wave plate having the first polarization, and passing the light reflected by the reflective linear polarizer through the first quarter-wave plate for subsequent reflection by the concave reflector; and for the light passed through the first quarter-wave plate having a second polarization that is orthogonal to the first polarization, passing the light having the second polarization through the reflective linear polarizer. Further, in any feasible combination: the operation of generating the light over the extended region may comprise generating the light from each of a plurality of localized-light-sources located within the extended region, wherein the operation of generating the light from each of the plurality of localized-light-sources located within the extended region may further comprise concentrating and directing the light from at least one of the plurality of localized-light-sources with a corresponding lens; the extended region over which the light is generated may comprise a two-dimensional region; the concave reflector may incorporate an optical axis of symmetry7that is parallel to and displaced from an axis substantially perpendicular to and centered about the reflective linear polarizer; the operation of reflecting the light from the concave reflector may comprise reflecting the light from a first-encountered surface of the concave reflector; the concave reflector may be configured in cooperation with the extended light source, the first quarter-wave plate, and the reflective linear polarizer so that an angular spread of the light exiting a relatively distal portion of the reflective linear polarizer is within 9degrees; the first quarter-wave plate may be tuned for operation at a wavelength within a midgreen range of wavelengths; the method may further comprise circularly polarizing the light prior to the reflection thereof by the concave reflector so that the light reflected by the concave reflector may be subsequently either reflected by or passed through the reflective linear polarizer; the method may further comprise masking the light reflected by the concave reflector that would not otherwise be passed through the first quarter-wave plate and subsequently acted upon by the reflective linear polarizer; the concave reflector may be configured in cooperation with the extended light source, the first quarter-wave plate, and the reflective linear polarizer so that an angular spread of the light exiting the reflective linear polarizer may be within 20 degrees; the method may further comprise: modulating the light passed through the reflective linear polarizer using the non-emissive image-display panel so as to impart image content thereto; forming a virtual image of the non-emissive image-display panel with an optical magnifier; and forming a real image of the extended light source with the optical magnifier, wherein the real image is formed at an exit pupil located proximate to an eye location, and the virtual image is formed at a viewing location that is displaced from the exit pupil and is viewable by an eye when the eye is located at the eye location; at least 60 percent of the light from the extended light source may passe through a viewable portion of the exit pupil that may be viewable by the eye when the eye may be located at the eye location; the non-emissive image-display panel may incorporate a plurality of imagemodulation pixels, and at each location within a portion of the exit pupil, the light of the exit pupil may be responsive to every image-modulation pixel of the plurality7of image-modulation pixels of the non-emissive image-display panel; wherein at least 60 percent of the light from the extended light source may passes through the portion of the exit pupil, for the eye located at the eye location, the portion of the exit pupil may be located and sized so as to provide for viewing by the eye of the portion of the exit pupil over a full range of rotations of the eye, a maximum of a vertical extent of the portion of the exit pupil and a horizontal extent of the portion of the exit pupil may not exceed 30 millimeters, and the extended light source may comprise a plurality of independently-controllable light emitters, further comprising adjusting or controlling a brightness of at least one of the plurality of independently-controllable light emitters relative to at least one other of the plurality of independently-controllable light emitters so that both the at least one of the plurality7of independently-controllable light emitters and the at least one other of the plurality of independently-controllable light emitters each exhibit a substantially uniform brightness in the portion of the exit pupil; and an eye-proximate surface of the optical magnifier may be located at least 8 millimeters from the exit pupil.

[0103] It should be understood, that any reference herein to the term “or” is intended to mean an “inclusive or” or what is also known as a “logical OR”, wherein when used as a logic statement, the expression “A or B” is true if either A or B is true, or if both A and B are true, and when used as a list of elements, the expression “A, B or C” is intended to include all combinations of the elements recited in the expression, for example, any of the elements selected from the group consisting of A, B, C, (A, B), (A, C), (B, C), and (A, B, C); and so on if additional elements are listed. Furthermore, it should also be understood that the indefinite articles "a" or "an", and the corresponding associated definite articles “the” or “said”, are each intended to mean one or more unless otherwise stated, implied, or physically impossible. Yet further, it should be understood that the expressions “at least one of A and B, etc.”, “at least one of A or B, etc.”, “selected from A and B, etc.” and “selected from A or B, etc.” are each intended to mean either any recited element individually or any combination of two or more elements, for example, any of the elements from the group consisting of “A”, “B”, and “A AND B together”, etc. Yet further, it should be understood that the expressions “one of A and B, etc.” and “one of A or B, etc.” are each intended to mean any of the recited elements individually alone, for example, either A alone or B alone, etc., but not A AND B together. Furthermore, it should also be understood that unless indicated otherwise or unless physically impossible, that the above-described embodiments and aspects can be used in combination with one another and are not mutually exclusive. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims, and any and all equivalents thereof.

[0104] What is claimed is:

Claims

CLAIMS1. A backlighting system for use with a non-emissive image-display panel, comprising: a. an extended light source; b. a concave reflector; c. a first quarter-wave plate; and d. a reflective linear polarizer, wherein said extended light source provides for generating light and is oriented so that said light impinges directly upon a reflective surface of said concave reflector; said first quarter-wave plate is located and oriented so as to receive said light reflected from said concave reflector; said reflective linear polarizer is located and oriented to receive said light reflected from said concave reflector and transmitted through said first quarter- wave plate; said reflective linear polarizer provides for reflecting said light reflected from said concave reflector and transmitted through said first quarter-wave plate having a first polarization direction, back through said first quarter-wave plate to be reflected from said concave reflector; said reflective linear polarizer provides for transmitting said light reflected from said concave reflector and transmitted through said first quarter- wave plate having a second polarization direction, wherein said second polarization direction is orthogonal to said first polarization direction; and said first quarter-wave plate provides for converting linearly-polarized light to circularly-polarized light, and vice versa.

2. A backlighting system for use with a non-emissive image-display panel as recited in claim 1. wherein said extended light source comprises a plurality of hght-emitting diodes.

3. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 1 and 2, wherein said extended light source comprises a plurality of localized-light- sources.

4. A backlighting system for use with a non-emissive image-display panel as recited in claim 3, further comprising in association with at least one localized-light-source of said plurality of localized-light sources, a corresponding lens that provides for concentrating and directing said light from said at least one localized-light-source of said plurality of localized-light- sources.

5. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 4, wherein said extended light source spans a two-dimensional region.

6. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 5, wherein said concave reflector incorporates an optical axis ofsymmetry that is substantially parallel to and displaced from an axis substantially perpendicular to and centered about said reflective linear polarizer.

7. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 6, wherein said concave reflector comprises a reflective first surface.

8. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 1 through 7, wherein a cavity between said concave reflector and said first quarterwave plate incorporates an optically-transparent solid material.

9. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 8, wherein said concave reflector is configured in cooperation with said extended light source, said first quarter-wave plate, and said reflective linear polarizer so that an angular spread of said light exiting a relatively distal portion of said reflective linear polarizer is within 9 degrees.

10. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 9, wherein said first quarter-wave plate is tuned for operation at a wavelength within a mid-green range of wavelengths.

11. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 10. wherein said first quarter-wave plate is flat.

12. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 11, wherein said reflective linear polarizer is flat.

13. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 12, further comprising: a. a transmissive linear polarizer located between said extended light source and said concave reflector; and b. a second quarter-wave plate located between said transmissive linear polarizer and said reflective linear polarizer,14. A backlighting system for use with a non-emissive image-display panel as recited in claim 13, wherein said second quarter-wave plate is tuned for operation at a wavelength within a mid-green range of wavelengths.

15. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 1 through 14. further comprising a reflective or absorptive mask that provides for blocking a portion of said light generated by said extended light source that would otherwise pass through or around said reflective linear polarizer following reflection from said concave reflector.

16. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 1 through 15, wherein said concave reflector is configured in cooperation with said extended light source, said first quarter-wave plate, and said reflective linear polarizer so that an angular spread of said light exiting said reflective linear polarizer is within 20 degrees.

17. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 1 through 16, further comprising said non-emissive image-display panel, wherein said non-emissive image-display panel is located so as to receive said light that passes through said reflective linear polarizer, and said non-emissive image-display panel provides modulating and transmitting therethrough said light passing through said reflective linear polarizer.

18. A backlighting system for use with a non-emissive image-display panel as recited in claim 17, wherein said non-emissive image-display panel incorporates said reflective linear polarizer.

19. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 17 and 18, wherein said reflective linear polarizer is bonded to said non-emissive image-display panel.

20. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 17 through 19, wherein said non-emissive image-display panel incorporates said first quarter-wave plate.

21. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 17 through 20. wherein said first quarter-wave plate is bonded to said reflective linear polarizer.

22. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 17 through 21, further comprising an optical magnifier located between said non- emissive image-display panel and an eye location, wherein said optical magnifier provides for receiving and processing therebetween said light from said non-emissive image-display panel, said optical magnifier in cooperation with said extended light source define an exit pupil, said exit pupil is proximate to said eye location for viewing a virtual image of said non-emissive image-display panel by an eye when said eye is at said eye location, and said virtual image is formed by said optical magnifier at a viewing distance that is displaced from said exit pupil.

23. A backlighting system for use with a non-emissive image-display panel as recited in claim 22, wherein said optical magnifier forms a real image of said extended light source at said exit pupil.

24. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 22 and 23, wherein said backlighting system is configured so that at least 60 percent of said light from said extended light source passes through a viewable portion of said exit pupil that is viewable by said eye when said eye is at said eye location.

25. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 22 through 24, wherein for at least a portion of said exit pupil, said light at each location of said portion of said exit pupil is responsive to every' pixel of said non-emissive image-display panel illuminated by said extended light source.

26. A backlighting system for use with a non-emissive image-display panel as recited in claim 25, wherein said backlighting system is configured so that at least 60 percent of said light from said extended light source passes through said portion of said exit pupil.

27. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 25 and 26, wherein for said eye located at said eye location, said portion of said exit pupil is located and sized so as to provide for viewing by said eye of said portion of said exit pupil over a full range of rotations of said eye.

28. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 25 through 27, wherein a maximum of a vertical extent of said portion of said exit pupil and a horizontal extent of said portion of said exit pupil does not exceed 30 millimeters.

29. A backlighting system for use with a non-emissive image-display panel as recited in any one of claims 25 through 28, wherein said extended light source comprises a plurality of independently-controllable light emitters, and a brightness of at least one of said plurality of independently-controllable light emitters is adjusted or controlled relative to at least one other of said plurality of independently-controllable light emitters so that both said at least one of said plurality7of independently-controllable light emitters and said at least one other of said plurality of independently-controllable light emitters each exhibit a substantially uniform brightness in said portion of said exit pupil.

30. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 22 through 29, wherein said optical magnifier comprises a catadioptric optical magnifier.

31. A backlighting system for use with a non-emissive image-display panel as recited in claim 30, wherein an eye-proximate surface of said catadioptric optical magnifier is curved.

32. A backlighting system for use with a non-emissive image-display7panel as recited in claims 30, wherein an eye-proximate surface of said catadioptric optical magnifier is flat.

33. A backlighting system for use with anon-emissive image-display panel as recited in any one of claims 22 through 32, wherein an eye-proximate surface of said optical magnifier is located at least 8 millimeters from said exit pupil.

34. A method of illuminating a non-emissive image-display panel, comprising: a. generating light over an extended region using an extended light source; b. directing said light at a concave reflector; c. reflecting said light from said concave reflector; d. passing said light reflected from said concave reflector through a first quarter-wave plate that converts circularly-polarized light to linearly-polarized light and vise versa; e. for said light passed through said first quarter-wave plate having a first polarization, reflecting with a reflective linear polarizer said light passed through said first quarterwave plate having said first polarization, and passing said light reflected by said reflective linear polarizer through said first quarter-wave plate for subsequent reflection by said concave reflector; and f. for said light passed through said first quarter-wave plate having a second polarization that is orthogonal to said first polarization, passing said light having said second polarization through said reflective linear polarizer.

35. A method of illuminating a non-emissive image-display panel as recited in claim 34, wherein the operation of generating said light over said extended region comprises generating said light from each of a plurality of localized-light-sources located within said extended region.

36. A method of illuminating a non-emissive image-display panel as recited in any one of claims 35, wherein the operation of generating said light from each of said plurality of localized- light-sources located within said extended region further comprises concentrating and directing said light from at least one of said plurality of localized-light-sources with a corresponding lens.

37. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 36, wherein said extended region over which said light is generated comprises a two-dimensional region.

38. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 37, wherein said concave reflector incorporates an optical axis of symmetry that is substantially parallel to and displaced from an axis substantially perpendicular to and centered about said reflective linear polarizer.

39. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 38, wherein the operation of reflecting said light from said concave reflector comprises reflecting said light from a first-encountered surface of said concave reflector.

40. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 39, wherein said concave reflector is configured in cooperation with said extended light source, said first quarter-wave plate, and said reflective linear polarizer so that an angular spread of said light exiting a relatively distal portion of said reflective linear polarizer is within 9 degrees.

41. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 40, wherein said first quarter-wave plate is tuned for operation at a wavelength within a mid-green range of wavelengths.

42. A method of illuminating a non-emissive image-display panel as recited in any one of claims34 through 41, further comprising circularly polarizing said light prior to the reflection thereof by said concave reflector so that said light reflected by said concave reflector is subsequently either reflected by or passed through said reflective linear polarizer.

43. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 42, further comprising masking said light reflected by said concave reflector that would not otherwise be passed through said first quarter-wave plate and subsequently acted upon by said reflective linear polarizer.

44. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 43, wherein said concave reflector is configured in cooperation with said extended light source, said first quarter-wave plate, and said reflective linear polarizer so that an angular spread of said light exiting said reflective linear polarizer is within 20 degrees.

45. A method of illuminating a non-emissive image-display panel as recited in any one of claims 34 through 44, further comprising: a. modulating said light passed through said reflective linear polarizer using said non- emissive image-display panel so as to impart image content thereto; b. forming a virtual image of said non-emissive image-display panel with an optical magnifier; and c. forming a real image of said extended light source with said optical magnifier, wherein said real image is formed at an exit pupil located proximate to an eye location, and said virtual image is formed at a viewing location that is displaced from said exit pupil and is viewable by an eye when said eye is located at said ey e location.

46. A method of illuminating a non-emissive image-display panel as recited in claim 45, wherein at least 60 percent of said light from said extended light source passes through a viewable portion of said exit pupil that is viewable by said eye when said eye is located at said eye location.

47. A method of illuminating a non-emissive image-display panel as recited in any one of claims 45 and 46, wherein said non-emissive image-display panel comprises a plurality of imagemodulation pixels, and at each location within a portion of said exit pupil, said light of said exit pupil is responsive to even’ image-modulation pixel of said plurality of image- modulation pixels of said non-emissive image-display panel.

48. A method of illuminating a non-emissive image-display panel as recited in claim 47, wherein at least 60 percent of said light from said extended light source passes through said portion of said exit pupil.

49. A method of illuminating a non-emissive image-display panel as recited in any one of claims 47 and 48, wherein for said eye located at said eye location, said portion of said exit pupil is located and sized so as to provide for viewing by said eye of said portion of said exit pupil over a full range of rotations of said eye.

50. A method of illuminating a non-emissive image-display panel as recited in any one of claims 47 through 49, wherein a maximum of a vertical extent of said portion of said exit pupil and a horizontal extent of said portion of said exit pupil does not exceed 30 millimeters.

51. A method of illuminating a non-emissive image-display panel as recited in any one of claims 47 through 50, wherein said extended light source comprises a plurality of independently- controllable light emitters, further comprising adjusting or controlling a brightness of at least one of said plurality of independently-controllable light emitters relative to at least one other of said plurality’ of independently-controllable light emitters so that both said at least one of said plurality of independently-controllable light emitters and said at least one other of said plurality of independently-controllable light emitters each exhibit a substantially uniform brightness in said portion of said exit pupil.

52. A method of illuminating a non-emissive image-display panel as recited in any one of claims 45 through 51, wherein an eye-proximate surface of said optical magnifier is located at least 8 millimeters from said exit pupil.

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