WO1995034841A1

WO1995034841A1 - Stereoscopic viewing apparatus and method

Info

Publication number: WO1995034841A1
Application number: PCT/US1995/007511
Authority: WO
Inventors: Eyal Fishler
Original assignee: Israel, Henry; F.B.S. Technologies Ltd.
Priority date: 1994-06-15
Filing date: 1995-06-13
Publication date: 1995-12-21
Also published as: AU2826795A

Abstract

A system for presenting a 3-dimensional picture to an observer comprises a display monitor (10) for displaying left- and right-eye side-by-side images, and a pair of optical fiber bundles (13) each for directing a respective one of the images to a respective eye of the observer (14). At opposite ends of the optical fiber bundles are disposed respective lens couplets for matching the display image to the optical fiber bundle and the image propagated therethrough to the eyes of the viewer. Preferably, a spatial filter is disposed between the lenses of the two lens couplets for preventing transmission of unwanted light.

Description

Stereoscopic Viewing Apparatus and Method

FIELD OF THE INVENTION

This invention relates to a stereoscopic viewing apparatus and method for viewing two side-by-side images simultaneously displayed on a display monitor.

BACKGROUND OF THE INVENTION

With the increasing trend to provide ever more realistic computer graphics programs and, in particular, to the increasing interest in so-called "virtual reality", the need for viewing graphical images as 3-dimensional is becoming increasingly common. U.S. Patent No. 5,126,878 (Trumbull et al.) discloses a stereoscopic viewing apparatus and a related method for providing a 3-dimensional effect for a viewer based on a side-by-side display on a conventional video screen of related left and right images that are each horizontally compressed. The viewer wears special headgear containing a disanamorphic lens in each eyepiece so as to present the two side-by-side images to the respective eyes of the viewer. The two side-by- side images are spatially displaced so that, when viewed simultaneously by the respective eyes of the viewer, a single, 3-dimensional image is perceived. A drawback with such an approach is that any natural tendency of the viewer to move relative to the display screen detracts from the quality of the 3-dimensional effect on account of inevitable changes in the optical paths of the left and right images relative to the respective eyes of the viewer.

Such a drawback is overcome by constraining the user's head within a suitable headgear having fixedly mounted thereto a pair of small display monitors for presenting the left and right images to the respective eyes. This approach is commonly used in virtual-reality devices. However, experience to date indicates that this approach is dangerous owing to the close proximity of the display monitors to the user's eyes with the consequent danger of X-ray leakage from the display screens.

U.S. Patent No. 4,862,873 (Yajima et al.) discloses a stereo endoscope having two optical lines carrying an optical image and a third optical line for conveying light to an object to be imaged. An optical system has a function of imaging at the end surface of the optical guide. By transmitting an illuminating light, via the third optical line, from the other end surface to the portion to be observed through one of the optical guides, the portion to be observed is illuminated. The optical image transmitted through the other optical guide is introduced into an ocular system or an imaging system. In such a system, a 3-dimensional effect is produced by the natural mutual displacement of the optical fibers relative to the object which is imaged thereby. Such an approach does not easily lend itself to directing respective side-by-side images displayed simultaneously on a display monitor to the respective eyes of a viewer owing to the very much greater area of the display images which requires careful matching of the images to the optical fibers. Such a problem does not occur with the stereoscopic endoscope described by Yajima et al. because the objects viewed by the endoscope are within the field of view thereof. Furthermore, if the display monitor displays color images, then each pixel is actually made up of three dots each representing a respective orthogonal color (e.g. Red, Blue and Green). In this case, very careful matching is required between the optical fibers and the color pixels in order to preserve correct color balance and resolution.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method and system for presenting 3-dimensional pictures to an observer in which the drawbacks of hitherto-proposed methods and systems are significantly reduced, or eliminated.

According to a broad aspect of the invention there is provided a system for presenting a 3-dimensional picture to an observer, comprising: a display monitor for displaying left- and right-eye side-by-side images, and at least two optical fibers for directing a respective one of the images to a respective eye of the observer.

Preferably, a pair of optical fiber bundles is employed, at opposite ends of which are disposed respective lens couplets for matching the display image to the optical fiber bundle and the image propagated therethrough to the eyes of the viewer. Preferably, a spatial filter is disposed between the lenses of the two lens couplets for preventing transmission of unwanted light.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how the same may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figs, la and lb are schematic representations of front and side elevations, respectively, of a system according to the invention;

Figs, lc and Id are further schematic representations of details of the system shown in Figs, la and lb; Figs. 2a, 2b and 2c are pictorial representations relating to the need to match color pixels of a color display monitor to the discrete fibers of an optical fiber bundle; and

Figs. 3 and 4 are pictorial representations of optical systems disposed at opposite ends of each fiber optic bundle for matching the image thereto.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Figs, la to Id show a display monitor designated generally as 10 for displaying two side-by-side images 11 and 12 corresponding, respec¬ tively, to left- and right-eye images. A pair of optical fiber bundles 13 (of which one is shown in

Fig. lb) is disposed between a corresponding one of the images 11 and 12 and a corresponding eye 14 of an observer for directing the respective image to the respective eye of the observer. Each optical fiber bundle 13 is mounted in fixed, spatial relationship to the display monitor 10 and to the eyes 14 of the observer so that the observer is free, within reason, to move his head relative to the display monitor 10 without losing the 3-dimensional effect. To this end, suitable pairs of mounts 15 and 16 are provided for accommodating therein the required optics. The mounts 15 are removably housed within a hood assembly 17 which overlays the display monitor 10 and is provided with appropriate apertures for accommodating the mounts. The opposite pair of mounts 16 are housed in a headgear 18 worn by the observer and are connected to the hood assembly 17 by means of a wire 19 attached to a yoke 20 connected to the mounts 16. D -

The wire 19 has a length which is less than that of the two optical fibers 13 so that it becomes taut before strain is applied to the optical fibers 13. Thus, the wire 19 constitutes a strain release means which releases the mounts 16 from the headgear 17 if too great a strain is placed on the optical fiber bundle 13 owing to excessive movement of the observer's head, thereby preventing damage to either the optical fiber bundle 13 or the mounts 15 and 16.

As stated, the mounts 15 and 16 also contain optical systems for matching the optical fiber bundle 13 to the display images and the eye 14 of the observer. Fig. 2a shows schematically R, B and G color dots which, in combination, constitute pixels designated generally as 21 of a color display monitor. In order to preserve ideal color balance, each of the color dots would need to be transmitted exactly through a corresponding fiber of the optical fiber bundle as shown in Fig. 2a wherein the outline of an imaginary optical fiber 22 is shown dotted around the circumference of the color dots. In practice, this is not possible. The diameter of the color pixels themselves is in the order of 100 μm whilst that of the optical fiber is only 10 μm. Therefore, the light emitted by the color dots must be matched to the optical fibers in order to preserve correct color balance and resolution. In Fig. 2b there is shown schematically an arrangement wherein each color dot (R, B and G) is imaged on to an optical fiber bundle 23 at the same size but not aligned. Thus, it will be seen that each optical fiber overlaps three color dots so as to transmit a portion of each of the three dots therethrough. Here, light is lost since there exist parts of each color dot which are not imaged by any fiber. Consequently, the resulting picture will not be sufficiently bright even though color balance is maintained since an equal proportion of each of the three color dots is transmitted through each optical fiber. Fig. 2c shows an alternative arrangement whereby each optical fiber 24 has a much larger effective aperture so as to overlap a complete pixel comprising the three orthogonal color dots R, B and G. Here, color balance, brightness and resolution are lost. Thus, color balance is lost because each optical fiber transmits different portions of the three orthogonal colors; brightness is lost because some component of each color dot is not transmitted by any of the optical fibers; and resolution is lost because fractional pixel data is transmitted thereby resulting in an overall loss of definition. Loss of brightness is not a problem since there is, in any case, too much light. However, color balance is a problem which is not recoverable optically. This consideration constrains the resolution to the dot size and not the pixel size. Loss of resolution is a problem also with monochrome display monitors since here, also, unless the optical fibers can be matched exactly to the pixels (in practice, an impossibility), only fractional pixel data is transmitted, resulting in overall loss of definition.

Image quality is a second consideration. A standard VGA display comprises 1000 x 1000 pixels. Dividing this display so as to produce two side-by-side images (one for each eye) allows approximately 500 x 500 usable pixels for each image. This is approximately the image quality of a CGA or EGA display. The images themselves are produced under control of suitable software (which is not itself a feature of the present invention) which takes into account the field geometry for each of the two views so as to maintain the proper relationship therebetween.

It is thus apparent that each of the display images 11 and 12 must be matched to the respective optical fiber bundles and that the images propagated by the respective optical fiber bundles must also be matched to the respective eyes of the viewer. Figs. 3 and 4 are optical diagrams showing schematically how such matching may be achieved in practice. Thus, a first lens couplet comprising lenses 25 and 26 is disposed between the display monitor 10 and the optical fiber bundle 13, as shown in Fig. 3, whilst, as shown in Fig. 4, a second lens couplet comprising lenses 28 and 29 is disposed between the optical fiber bundle 13 and the observer.

The first lens couplet comprising lenses 25 and 26 reduces the effective size of the pixels 30 so that each pixel may be imaged by a single optical fiber

31. In contrast, the second lens couplet comprising lenses 28 and 29 operates in an opposite manner so as to restore the effective size of the pixels 32 imaged by each optical fiber to their original size. In order to prevent light from adjacent pixels being imaged by the same optical fiber, there is disposed between the lenses 25 and 26 of the first lens couplet a spatial filter 33 comprising a disk having a small aperture, or pin-hole, therethrough for allowing only the light emanating from the desired pixels to pass through the lens couplet to the appropriate fiber 31 of the optical fiber bundle 13. Concomitantly, a spatial filter 34 is disposed between the two lenses 28 and 29 of the second lens couplet in order to ensure that each effective pixel 32 viewed by the observer emanates from a single optical fiber. Also disposed between the spatial filter 34 and the lens 29 is a neutral density filter 35 for reducing the brightness of the image seen by the observer, thereby reducing discomfort and risk of eyestrain. It will be appreciated that whilst, in the preferred embodiment, two optical fiber bundles are employed, in fact a single optical fiber bundle can be used, there being included therein two separate cores of optical fibers for transmitting the left- and right-eye images.

Claims

CLAIMS:

1. A method for presenting 3-dimensional pictures to an observer, comprising the steps of:

(a) displaying left- and right-eye images on respective non-inter- leaved portions of a display device, and

(b) directing each of the images to corresponding eyes of the observer via at least one respective optical fiber.

2. The method according to Claim 1, wherein each image is directed to the respective eye of the observer via an respective optical fiber bundle.

3. The method according to Claim 1, wherein each of the images is matched to the respective fiber bundle by a respective lens.

4. The method according to Claim 3, wherein there is further included the step of spatially filtering the images prior to directing them through the optical fiber bundle so as to improve resolution.

5. The method according to Claim 4, wherein the displayed image is a color image.

6. The method according to Claim 4, wherein the displayed image is a monochrome image.

7. The method according to Claim 1, further including the step of matching the images to a respective eye of the observer.

8. The method according to Claim 1, further including the step of reducing the brightness of each of the images.

9. A system for presenting a 3-dimensional picture to an observer, the system comprising: a display monitor for displaying left- and right-eye side-by-side images, and at least two optical fibers for directing a respective one of the images to a respective eye of the observer.

10. The system according to Claim 9, wherein the at least two optical fibers are constituted by at least one optical fiber bundle.

11. The system according to Claim 10, including a first lens couplet disposed between the display monitor and each optical fiber bundle for matching the display image to the optical fiber bundle.

12. The system according to Claim 11, including a second lens couplet between each optical fiber bundle and the observer for matching light propagated through tjie lens to the eyes of the observer.

13. The system according to Claim 11, wherein there is further included a spatial filter disposed between the lenses of said first lens couplet for preventing unwanted light transmitted by the display images from propagating through the optical fiber bundle and thereby improving resolution.

14. The system according to Claim 12, wherein there is further included a spatial filter disposed between the lenses of the second lens couplet for preventing unwanted light propagated through the optical fiber bundle from reaching the eyes of the observer.

15. The system according to Claim 13, wherein the display monitor is a color device.

16. The system according to Claim 14, wherein the display monitor is a color device.

17. The system according to Claim 9, further including a neutral density filter between the optical fiber bundle and the eyes of the observer for reducing the image brightness.

18. The system according to Claim 9, further including: a first mount maintained in fixed spatial relationship with the display images for accommodating the optical fiber bundle and preventing displacement thereof relative to the display images, and a second mount maintained in fixed spatial relationship with the observer for accommodating the optical fiber bundle and preventing displacement thereof relative to the observer.

19. The system according to Claim 18, wherein the first mount is housed within a hood assembly which overlays the display monitor and is provided with a pair of apertures therein for allowing the passage there¬ through of the light emitted by the two images.

20. The system according to Claim 19, wherein the second mount is housed within a headgear worn by the observer.

21. The system according to Claim 18, further including a strain release means coupled between the first and second mounts for preventing damage to either the optical fiber bundle or to said mounts if too great a strain is placed on the optical fiber bundle.

22. The system according to Claim 21, wherein: the second mount is removably housed within a headgear worn by the observer, and the strain release means comprises a wire connected between the hood assembly and the second mounts and having a length which is less than that of the optical fiber bundle so that it becomes taut before strain is applied to the optical fiber bundle, thereby removing the second mount from the headgear and preventing damage to either the optical fiber bundle or to said mounts if too great a strain is placed on the optical fiber bundle.