WO2009136393A1

WO2009136393A1 - Wide angle helmet mounted display system

Info

Publication number: WO2009136393A1
Application number: PCT/IL2009/000462
Authority: WO
Inventors: Sasson Abraham; Joseph Yaeli; Aron Arlievsky; Abraham Reichart; Yosi Arazi
Original assignee: Elbit Systems Ltd.
Priority date: 2008-05-06
Filing date: 2009-05-04
Publication date: 2009-11-12

Abstract

Compact head mounted monocular display system (100), mounted on top of a head-gear, having a large field of view comprising: a projector (124), and an elliptic visor(llθ), the projector (124) is mounted on the head gear, for projecting an image to a user of the head mounted display system(lOO), the projector (124) being located off the optical axis (132) of a selected single eye (112) of the user of the head mounted monocular display system, the elliptic visor (110) is mounted on the head gear, for reflecting the image from the projector (124) toward the selected single eye (112) of the user, the image being visible to the selected single eye (112) and invisible to the other eye of the user, the elliptic visor (110) being in the shape of a portion of a surface of an ellipsoid, the elliptic visor (110) being positioned in front of the selected single eye (112) of the user. The projector (124) includes an image source (102) for projecting the image, a relay optics assembly (104), optically coupled with the image source (102), for relaying the image, and a toroidal mirror(106), optically coupled with the relay optics assembly (104), for correcting the aberrations resulting from the off-axis orientation of the projector (124).

Description

WIDE ANGLE HELMET MOUNTED DISPLAY SYSTEM

FIELD OF THE DISCLOSED TECHNIQUE

The disclosed technique relates to HMDs with wide field of view, in general, and to a system for projecting an image on a visor, substantially without distortion, in particular.

BACKGROUND OF THE DISCLOSED TECHNIQUE

Helmet projection systems are known in the art. A projector is mounted on the helmet, and projects an image onto a visor of the helmet. The visor reflects the projected image toward an eye of a user of the helmet. The visor is semi-transparent and combines the out side scenery with the projected image. A small and light weight projection system is more convenient to the user than a larger cumbersome projection system. Projected image, having a large field of view, usually increases the amount of optical distortions needed to be corrected electronically on the display source before presenting the image to the user (i.e., as detailed with reference to Figure 2 of US patent No. 6,356,393 to Potin). The helmet projection systems, known in the art, are either monochromatic projection systems or polychromatic projection systems.

U.S. Patent 5,880,888, to Schoenmakers et al, entitled "Helmet Mounted Display System" is directed at a head mounted system for combining a display image with the field of view of a viewer, the system permits a wide field of view (i.e., the field of view is limited to about 30 degrees).

U.S. Patent Application 2006/0250696, to McGuire, entitled "Head Mounted Display Devices" is directed at a head mounted display including an off-axis combiner and a non rotationally symmetric optical element having a first and a second lens surfaces that are tilted and de-centered there between. The head mounted display corrects off-axis aberrations at a plurality of lenses (imaging optics 406).

SUMMARY OF THE PRESENT DISCLOSED TECHNIQUE

It is an object of the disclosed technique to provide a novel compact head mounted display system for projecting a wide field of view image on a visor, substantially without distortion. In accordance with the disclosed technique, there is thus provided a compact head mounted monocular display system, mounted on top of a head-gear, having a large field of view. The system includes a projector and an elliptic visor. The projector is mounted on the head gear, for projecting an image to a user of the head mounted display system. The projector is located off the optical axis of a selected single eye of the user of the head mounted monocular display system. The elliptic visor is mounted on the head gear, for reflecting the image from the projector toward the selected single eye of the user. The image is visible to the selected single eye and invisible to the other eye of the user. The elliptic visor is in the shape of a portion of a surface of an ellipsoid. The elliptic visor is positioned in front of the selected single eye of the user. The projector includes an image source, a relay optics assembly, and a toroidal mirror. The image source is for projecting the image. The relay optics assembly is optically coupled with the image source, for relaying the image. The toroidal mirror is optically coupled with the relay optics assembly, for correcting the aberrations resulting from the off-axis orientation of the projector.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed technique will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Figure 1 is a schematic illustration of a system for projecting an image on a visor, constructed and operative in accordance with an embodiment of the disclosed technique;

Figures 2A and 2B are schematic illustrations of a system for projecting an image on a visor, constructed and operative in accordance with a another embodiment of the disclosed technique;

Figure 3 is a schematic illustration of a system for projecting an image on a visor, constructed and operative in accordance with a further embodiment of the disclosed technique;

Figure 4 is a schematic illustration of an image depicting the distortion of a projected image on the plane of an image source in accordance with another embodiment of the disclosed technique; and

Figures 5A and 5B are schematic illustrations of a system for projecting an image on a visor, constructed and operative in accordance with a further embodiment of the disclosed technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosed technique overcomes the disadvantages of the prior art by providing a novel optical configuration for a Head Mounted Display (HMD). The optical configuration, according to the disclosed

5 technique, includes an image source, relay optics assembly and a toroidal mirror, placed at the optical path of the image to be displayed. The system projects the image on an elliptic visor. A user views the image projected on the elliptic visor. The toroidal mirror corrects off-axis optical aberrations in the image. These aberrations are due to substantially wide0 spatial projection angles. The optical configuration according to the disclosed technique significantly reduces the optical aberrations of the projected image (i.e., distortion of less than 10 percent). According to another aspect of the disclosed technique, more than one image source can be used for projecting an image or images, by using a beam splitter,5 placed at the optical path leading to the correcting optics assembly and the toroidal mirror. The term "wide field of view" herein below, refers to a field of view larger than 60 degrees.

Reference is now made to Figure 1 , which is a schematic illustration of a system, generally referenced 100, for projecting an image0 on a visor, constructed and operative in accordance with an embodiment of the disclosed technique. System 100 is a monocular projection system. System 100 includes a projector 124 and an elliptic visor 110. Projector 124 projects a Wide Field of View (FOV - i.e., at least 60 degrees) image onto elliptic visor 110. Elliptic visor 110 reflects the FOV image onto an5 eye 112 of a user (not shown).

Projector 124 includes an image source 102, relay optics assembly 104, a toroidal mirror 106, and a folding lens 108. Optical axis 132 (i.e., the imaginary continuation of the central light beam entering eye 112) of the eye 112 of a user is tilted with respect to optical axis 130 (i.e.,o the imaginary continuation of the central light beam produced at image source 102) of image source 102, in two perpendicular directions (i.e. double off-axis geometry). It is noted that, an optical axis of an optical element, as described herein below, refers to the optical axis which is the imaginary continuation of the central light beam going through the center of that optical element. Relay optics assembly 104 is optically coupled with image source 102 and with toroidal mirror 106. Folding lens 108 is optically coupled with toroidal mirror 106 and with elliptic visor 110. Image source 102 projects an image (not shown) toward toroidal mirror 106 through relay optics assembly 104. Relay optics assembly 104 relays the projected image toward toroidal mirror 106. Toroidal mirror 106 corrects the aberrations of the projected image, and reflects the corrected image toward elliptic visor 110, via folding lens 108.

The image projected by image source 102 passes through surface 128. The projected image is reflected by reflecting surface 126 and passes through surface 128 toward elliptic visor 110. Elliptic visor 110 reflects the corrected and reflected image toward eye 112 of the user. Elliptic visor 110 combines the corrected and reflected image with light coming from the outside scenery (not shown). It is noted, that Figure 1 illustrates system 100 from a side view perspective. System 100 is a three dimensional system (i.e., system 100 extends from the plane of Figure 1).

Image source 102 is, for example, a Liquid Crystal on Silicon (LCOS) display, a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT), and the like. Alternatively, image source can include a plurality of image sources combined through a beam splitter (as further explained in conjunction with Figure 2B). Each of the image sources can project a different image, a similar image of different monochromatic frequencies, and the like.

Relay optics assembly 104 includes a plurality of lenses and prisms 114, 116, 118, 120, and 122, which have spherical and a-spherical surfaces. Relay optics assembly 104 relays the projected image toward toroidal mirror 106, which compensates for the distortions of the image projected by image source 102, resulting from the double off-axis geometry. Image portions, which are unused, are trimmed, as detailed further with reference to Figure 4. It is noted that, it is essential to keep the trimmed image portions to a minimum, in order to project to the user as many details of the original image as possible. The back focus of relay optics assembly 104 is large enough to enable the insertion of a beam splitter (Figure 2) between image source 102 and relay optics assembly 104.

Toroidal mirror 106 is a reflecting surface with a first curvature in a first direction and a second curvature in a second, perpendicular, direction. The first radius of toroidal mirror 106 (i.e., the radius in the first direction) can be different from the second radius of toroidal mirror 106 (i.e., the radius in the second direction, which is perpendicular to the first direction). Toroidal mirror 106 compensates for the distortion caused by the double off-axis geometry during reflections. The fact that toroidal mirror 106 complements relay optics assembly 104 in the image correction, enables relay optics assembly 104 to include less lenses and prisms (i.e., relative to a configuration with no toroidal mirror correcting the image aberrations). Thus, relay optics assembly 104 is reduced in both size and weight. Alternatively, toroidal mirror 106 is replaced by a double curved reflecting surface (i.e., a reflective surface having a first curve in a first direction and a second curve in a second, perpendicular, direction). The first curvature radius of the double curved reflecting surface is different than the second curvature radius. Folding lens 108 diverts the beams from the forehead of the user to a location convenient to handle (i.e., a location the visor can reflect the image there from). As seen in Figure 1 , the positioning of folding lens 108 between toroidal mirror 106 and visor 110 decreases the off axis configuration of system 100 (i.e., optical axis 130 is better aligned with optical axis 132). Thus, the aberrations, produced by the off axis configuration are decreased as well. Folding lens 108 includes an entrance refracting surface 128, a reflecting surface 126, and an exit surface 128. In the example set forth in Figure 1 , folding lens 108 includes a single reflecting surface 126. Alternatively, folding lens 108 includes a plurality of reflecting surfaces (i.e., such as in a periscope). In the example set forth in Figure 1 entrance surface 128 and exit surface 128 are combined and form a single entrance and exit surface 128. Alternatively, the entrance surface may be separate from the exit surface, and each of the surfaces can have its own shape, which is generally aspheric. In the example set forth in Figure 1 , reflecting surface 126 is planar. It is noted that, reflecting, surface 126 can have other aspheric shapes, such as an ellipsoid, a hyperboloid, and the like.

Elliptic visor 110 is a semi-transparent visor, and it combines incoming light from the outside scenery with light reflected from folding lens 108. Elliptic visor 408 is in the shape of a segment of a surface of a rotational ellipsoid. It is noted, that projection system 100 is a relatively compact system. Despite its compactness, projection system 100 can project image of a relative large Field of View (FOV). The width of the FOV of projection system 100 is about 60 degrees and the height of the FOV of projection system 100 is about 40 degrees for a typical light tube of about 40 mms. Elliptic visor 110 enables projection system 100 to be compact.

As mentioned above, according to another aspect of the disclosed technique, the HMD optical configuration may include a beam splitter between the image source and the relay optical assembly. This beam splitter enables more than one image to be projected on the elliptic visor (e.g., different images, images of different colors).

Reference is now made to Figures 2A and 2B, which are schematic illustrations of a system, generally referenced 200, for projecting an image on a visor, constructed and operative in accordance with a another embodiment of the disclosed technique. With reference to Figure 2A, system 200 is a monocular projection system. System 200 includes a projector 234 and an elliptic visor 220. Projector 234 includes a reflecting image source 202 (e.g., LCOS), a field lens 204, a beam splitter 206, a light source 208, a light polarizer 210, an image polarizer 212, a relay optics assembly 214, a toroidal mirror 216, and a folding lens 220. Reflecting image source 202, field lens 204, beam splitter 206, image polarizer 212, relay optics assembly 214, and toroidal mirror 216 are positioned on a first optical axis (the optical axis of image source 202), in this respective order. Light source 208, light polarizer 210, and beam splitter 206 are positioned on a second optical axis (i.e., the optical axis of light source 208), which is tilted with respect to the first optical axis (i.e., beam splitter 206 is positioned on the crossing point of the first optical axis and the second optical axis). Beam splitter 206 is optically coupled with reflecting image source 202, via field lens 204, and with image polarizer 212 (i.e., along the first optical axis). Beam splitter 206 is further optically coupled with light source 208, via light polarizer 210 (i.e., along the second optical axis). Relay optics assembly 214 is optically coupled with Image polarizer 212 and with toroidal mirror 216 (i.e., along the first optical axis). Folding lens 218 is optically coupled with toroidal mirror 216 and with elliptic visor 220. Light source 208 radiates light through light polarizer 210, toward beam splitter 206. Light polarizer 210 polarizes the light radiated from light source 208. Beam splitter 206 reflects at least a portion of the polarized light toward reflecting image source 202. Beam splitter 206 may be a polarizing beam splitter. Thus, no light is transmitted from light source 208 through beam splitter 206. Reflecting image source 202 reflects back some of the polarized light, as an image (not shown) to be projected, toward toroidal mirror 216. Reflecting image source 202 reflects the image toward toroidal mirror 216 via image polarizer 212, and relay optics assembly 214. Toroidal mirror 216 reflects the relayed image toward elliptic visor 220 via folding lens 218. Elliptic visor 220 reflects the corrected image toward an eye 222 of a user (not shown). Reflecting image source 202, field lens 204, light source 208, light polarizer 210, and image polarizer 212 form an image source, substantially similar to image source 102 (Figure 1). Beam splitter 206 enables more than one image source, to project images to be displayed, simultaneously (i.e., beam splitter 206 operates as a beam combiner). In the example set forth in Figure 2A, beam splitter 206 is planar. Alternatively, beam splitter 206 may be curved.

The first optical Axis is tilted with respect to the optical axis (not shown) of eye 222 of the user of projection system 200, in two perpendicular directions (i.e., double off-axis geometry). The double off-axis geometry creates aberrations on the image reflected from reflecting image source 202 toward eye 222. The aberrations caused by the double off-axis geometry are in two perpendicular directions (not shown). Relay optics assembly 214, toroidal mirror 216, folding lens 218, and elliptical visor 220, are substantially similar to relay optics assembly 114, toroidal mirror 116, folding lens 108, and elliptical visor 120, all of Figure 1 , respectively. Thus, relay optics assembly 214 relays the image toward toroidal mirror 216, and toroidal mirror 216 corrects the image for distortion caused by the double off-axis geometry.

With reference to Figure 2B, system 200 includes a second image source 203 and the field optics of image source 203 (not shown). Second image source produces an image (e.g., the same image of image source 202 only in different color, a different image than the image of image source 202) and directs the image toward beam combiner 206. Beam combiner 206 combines the image reflected from image source 202 and the image produced by second image source 203 and directs the combined images toward toroidal mirror 216.

It is noted that in the example set forth in Figure 2B, image source 202 is a reflecting image source, and image source 203 is a radiating image source. Alternatively, system 200 includes any combination of image sources such as a plurality of radiating image sources, a plurality of reflecting image sources having at least one light source, a combination of at least one reflecting image source and at least one radiating image source, and the like. The plurality of image sources can produce a single image with a plurality of colors, a plurality of images, or a combination thereof.

According to a further embodiment of the disclosed technique, an image is projected to both eyes of a user. Reference is now made to Figure 3, which is a schematic illustration of a system, generally referenced 300, for projecting an image on a visor, constructed and operative in accordance with a further embodiment of the disclosed technique. Projection system 300 includes left projector 326L, right projector 326R, and a dual visor 324. Dual visor 324 includes left elliptic visor 32OL, and right elliptic visor 32OR. Projection system 300 is a binocular projection system, in which each of the branches of projection system 300 (i.e., the left branch including left projector 326_L and left elliptic visor 320_L, and the right branch including right projector 326_R and right elliptic visor 320_R) is substantially similar to monocular projection system 200 (Figure 2). Dual visor 324 is a double cupped visor, as elliptic visors 32OL and 32OR are mechanically coupled together to form the cups. Each of left projector 326L and right projector 326R is substantially similar to projector 234 (Figure 2). Each of left elliptic visor 32OL and right elliptic visor 32OR is substantially similar to elliptic visor 220 of Figure 2. Each ellipsoidic part of dual visor 324 is positioned in front of the respective single eye of the user (i.e., left elliptic visor 32OL is in front of left eye 322L, and right elliptic visor 32OR is in front of right eye 322R). The dimensions of each half of dual visor 324 are physically limited by the symmetry plane of the face of the user (i.e., each of left elliptic visor 32OL and right elliptic visor 32OR does not extend beyond the symmetry plane of the face of the user). It is noted that, in a monocular system (e.g., system 100 of Figure 1) the dimensions of the elliptic visor are not limited and can extend beyond the symmetry plane of the face of the user in order to enable a larger field of view.

A left eye 322ι_ and a right eye 322R, of a user (not shown) of projection system 300 are focused at infinity. Thus, the optical axes of eyes 322L and 322R are parallel to one another. The images projected onto dual visor 324, by left projector 326ι_ and right projector 326R, are parallel to one another, in the image space where they overlap, and appear as if they both come from infinity (i.e., right projector 326R projects an image to the right of the center of the image space where they overlap, and left projector 326L projects an image to the left of the center of the image space where they overlap). The content of the images projected by left projector 326_L and right projector 326_R may be mutually exclusive. Alternatively, the image projected by left projector 326_L and right projector 326_R may include common content projected to each eye.

Reference is now made to Figure 4, which is a schematic illustration of an image, generally referenced 400, depicting the distortion of a projected image on the plane of an image source in accordance with another embodiment of the disclosed technique. Image 400 includes a contour 402 of an actual image source (e.g., image source 102 of Figure 1 ), a contour 404 of a distorted projected image, and a contour 406 of a required image source.

Required image source contour 406, represents the contour of an image source required for displaying a FOV of forty degrees in the short direction, having a rectangular shape (i.e., the short side of rectangular contour 406) and sixty degrees in the long direction (i.e., the long side of rectangular contour 406) without any distortion (i.e., in an ideal system). Actual image source contour 402 is in the shape of a rectangle. Actual image source contour 402 represents an image source which provides a field of view of forty degrees in a short direction (i.e., the short side of rectangle 402), and a field of view of sixty degrees in a long direction (i.e., the long side of rectangle 402).

Distorted projected image contour 404 is distorted by going through a projection system (e.g., projector 124 and visor 110 of Figure 1). Projected image contour 404 is substantially in the shape of a trapezoid. A plurality of unused image portions 408 of image source contour 402 are not covered by projected image contour 404, because of the distortion of projected image contour 404.

The surface area of distorted image contour 404 is substantially similar to that of required image source contour 406. In order to compensate for the distortion of an image, projected by a projection system according to the disclosed technique (e.g., projection system 100 of Figure 1), the system according to the disclosed technique employs an image source having surface area bigger than the surface area required. In other words, for displaying the required FOV (i.e., forty degrees by sixty degrees), the system according to the disclosed technique employs image source 402 (i.e., an image source having a contour similar in size to image source contour 402), the surface area thereof is slightly larger than the surface area of required image source contour 406. It is noted that, in a projection system according to the disclosed technique (e.g., projection image 100 of Figure 1), unused image portions 408 are small (i.e., the area of unused image portions 408 is small in comparison with the area of image source 402). The surface area of distorted image source contour 404 is smaller than that of actual image source contour 402 by less than ten percent. That is, the distortion introduced to the projected image by the projection system is less than ten percent. Such a minor distortion decreases the need for an electronic distortion correction, such that the electronic correction is negligible and could even be unnecessary. It is noted that, an electronic distortion correction might affect the resolution of the projected image. Reference is now made to Figures 5A and 5B. Figure 5A is a schematic illustration of a top view of a system, generally referenced 500, for projecting an image on a visor, constructed and operative in accordance with a further embodiment of the disclosed technique. Figure 5B is a schematic illustration of a side view of system 500. with reference to Figure 5A, projection system 500 includes a left projector 502L, a right projector 502R, a dual visor 504, a left hinge 508L, a right hinge 508R, and a support bridge 510. Dual visor 504 includes a left elliptic visor 506L and a right elliptic visor 506R. Each of left projector 502ι_ and right projector 502R is substantially similar to projector 124 (Figure 1). Dual visor 504 is substantially similar to dual visor 324 (Figure 3).

Left elliptic visor 506L is mechanically coupled with right elliptic visor 506R to form dual visor 504. Dual visor 504 is coupled with left hinge 508L and with right hinge 508R, such that dual visor 504 is rotatable about an axis 512 connecting left hinge 508L with right hinge 508R. Left projector 502L is coupled between left hinge 508L and support bridge 510. Right projector 502R is coupled between right hinge 508R and support bridge 510. All of left hinge 508L, left projector 502L, support bridge 510, right projector 502R, and right hinge 508R form a single support structure 514. Dual visor 504 is rotatably mounted onto support structure 514.

Left hinge 508L and right hinge 508R enables dual visor 504 to rotate about axis 512. When dual visor 504 is positioned at a first stance (i.e., first angle of rotation about axis 512), each of left projector 502L and right projector 502R projects an image (not shown) substantially toward the first focus point (not shown) of each of left elliptic visor 506L and right elliptic visor 506R.

A user (not shown) can rotate dual visor 504 to a second stance (not shown), such that dual visor 504 is out of sight of the user. When the user rotates dual visor 504 back to the first stance, each of left projector 502L and right projector 502R will re-align with dual visor 504, since dual visor 504 is mounted on support structure 514 (i.e., left hinge 508L, left projector 502L, support bridge 510, right projector 502R, and right hinge 508R), via left hinge 508L and right hinge 508R. It is noted that, left projector 502L and right projector 502R are positioned within support structure 514 such that when dual visor 504 is rotated to the second stance, dual visor 504 does not come into contact with neither one of left projector 502L and right projector 502R.

With reference to Figure 5B, helmet mounted projection system 500 further includes a helmet 516. Support structure 514 (Figure 5A), which includes left hinge 508L, left projector 502L, support bridge 510, right projector 502R, and right hinge 508R is mounted on helmet 516. Dual visor 504 is mounted on support structure 514 via left hinge 508L and right hinge 508R, such that dual visor 504 is rotatable with respect to the support structure in the directions of double arrow 514, around axis 512.

Alternatively, helmet 516 can be replaced with a different head gear, such as a head band and the like. It will be appreciated by persons skilled in the art that the disclosed technique is not limited to what has been particularly shown and described hereinabove. Rather the scope of the disclosed technique is defined only by the claims, which follow.

Claims

1. Compact head mounted monocular display system, mounted on top of a head-gear, having a large field of view, comprising: a projector, mounted on said head gear, for projecting an image to a user of said head mounted display system, said projector being located off the optical axis of a selected single eye of said user of said head mounted monocular display system; and an elliptic visor, mounted on said head gear, for reflecting said image from said projector toward said selected single eye of said user, said image being visible to said selected single eye and invisible to the other eye of said user, said elliptic visor being in the shape of a portion of a surface of an ellipsoid, said elliptic visor being positioned in front of said selected single eye of said user; wherein said projector includes: an image source for projecting said image; a relay optics assembly, optically coupled with said image source, for relaying said image; and a toroidal mirror, optically coupled with said relay optics assembly, for correcting the aberrations resulting from the off-axis orientation of said projector.

2. The system of claim 1 , wherein said display system further comprises a second projector mounted on said head gear, and a second elliptic visor positioned in front of said other eye of said user, such that said system is binocular, said elliptic visor and said second elliptic visor are coupled together to form a single dual visor, wherein the dimensions of each of said first elliptic visor and said second elliptic visor are physically limited by the symmetry plane of the face of said user.

3. The system of claim 1 , wherein said projector further includes a folding lens, positioned in front of the forehead of said user and optically coupled with said toroidal mirror, said folding lens including: an entrance surface; a reflecting surface; and an exit surface; said image being reflected from said toroidal mirror toward said entrance surface, said image passing through said entrance surface toward said reflecting surface, said image being reflected at said reflecting surface toward said exit surface, said image passing through said exit surface toward said elliptic visor.

4. The system of claim 1 , wherein said image source is a reflecting image source comprising: a light source, for radiating light; an image source, for reflecting at least a portion of said light radiated by said light source as an image toward said relay optics; and a beam splitter, optically coupled between said light source and said image source, said beam splitter reflecting at least a portion of the light radiated by said light source toward said image source and for transmitting said image toward said relay optics.

5. The system of claim 1 , wherein said projector further includes a beam splitter positioned between said image source and said relay optics, wherein said beam splitter enabling at least two images to be projected towards said visor.

6. The system of claim 5, wherein said at least two images being projected by at least two image sources.

7. The system of claim 5, wherein said at least two images being projected by at least two light sources and are reflected toward said relay optics from at least one image source, said at least two light sources projecting light of a different color.

8. The system of claim 2, wherein said system further comprises a support structure mounted on said head gear, said support structure being firmly coupled with said projector, and rotatably coupled with said elliptic visor, such that said elliptic visor can be rotated out of the field of view of said user relative to said support structure to a position above the face of said user.

9. The system of claim 8, wherein said support structure includes: a left hinge; a support bridge; and a right hinge; wherein said first projector and said second projector are incorporated in said support structure, such that said first projector is coupled between said left hinge and said support bridge, and said right projector is coupled between said right hinge and said support bridge, and wherein said dual visor is rotatably coupled with said left hinge and with said right hinge.

10. The system of claim 1 , wherein said toroidal mirror is a reflecting surface having a first curvature in a first direction and a second curvature in a second direction, wherein said first direction and said second direction are perpendicular.