Optical correction for virtual reality and heads up displays

• US 5,642,227 A
• Filed: 06/06/1995
• Issued: 06/24/1997
• Est. Priority Date: 02/07/1992
• Status: Expired due to Fees

• Current Assignee: i-O Display Systems LLC (Ilixco, Inc.)
• Original Assignee: Virtual RS Corp.
• Inventors: Rallison, Richard Dennis
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US08/468,050
• Time in Patent Office: 749 Days
• Field of Search: 359/630, 359/631, 359/629, 359/633, 348/359, 358/484
• US Class Current: 359/631
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0116 comprising devices for correcting chromatic aberration
• CPC Class Codes: G02B 2027/0132 comprising binocular systems
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 6/08 with fibre bundle in form of plate

Abstract

The present invention eliminates the relay lens systems found in conventional helmet mounted displays (HMDs) by removing field distortions and aberrations with a contoured fiber optic faceplate placed in close proximity to a liquid crystal display (LCD) or cathode ray tube. The optical system typically consists of a spherical dielectric or holographically made collimator - combiner, a dielectric or holographically made fold mirror, and a contoured fiber optic faceplate. The fold mirror is flat, and the collimator - combiner is made by coating a spherical eye glass blank. The system is configured as a folded and tilted catadioptric projector with the novel feature being the contoured faceplate. There are no dispersive elements in the imaging assembly which means it can be completely polychromatic (full color) without the need for additional color correction optics as found in all refractive color systems. When designed for full color, highest brightness, and see through capability it must be made with two or three narrow spectral and angular sensitive coatings on the fold mirror and on the collimator - combiner. These coatings allow the use of a tilt of the collimator - combiner with respect to the fold mirror which induces a small amount of astigmatism and keystone distortion but at the same time allows image light to pass through the folded optics to the eye with a minimum of loss. The elimination of a corrective refractive lens relay system makes this design polychromatic, less expensive, and lighter in weight, compared to a similar system with an achromatized and corrected refractive lens.

Claims

1. A method for controlling the size of the energy window of a catadioptric HMD where the refractive relay lenses have been replaced with a fiber optic faceplate, comprising:

placing a first fiber optic faceplate to receive the image from the image generator;

locating a second fiber optic faceplate, which has smaller fibers with a higher numerical aperture than those of said first fiber optic faceplate, to receive the image from said first fiber optic faceplate; and

grinding the output surface of said second fiber optic faceplate finer to increase the angle at which it will scatter light.

2. A method for providing a head-mounted display device comprising:

providing an image generator for generating image light;

placing a first plate having fibers defining an input surface and an output surface with said input surface adjacent said image generator to receive said image light and provide said image light to said output surface;

positioning a second plate having an input surface and an output surface with the input surface of said second plate adjacent the output surface of the said first plate, wherein said second plate comprises fibers which are smaller in diameter than the fibers of the first plate.

3. A method as claimed in claim 2 further comprising:

positioning a fold mirror for receiving image light output at the output surface of said second plate and reflecting said image light away from the eye of the user;

positioning a reflector to receive said image light transmitted in said first direction and reflect said image light toward the eye of the user.

4. A method for providing a head-mounted display device comprising:

providing an image generator for generating image light;

placing a first plate having fibers defining an input surface and an output surface with said input surface adjacent said image generator to receive said image light and provide said image light to said output surface;

positioning a second plate having an input surface and an output surface with the input surface of said second plate adjacent the output surface of the said first plate, wherein said second plate comprises fibers which are smaller in diameter than the fibers of the first plate;

treating said output surface of said second plate to provide surface roughness sufficiently great to achieve a desired energy window, but sufficiently smooth to avoid substantially degrading image resolution.

5. Head-mounted display apparatus comprising:

an image generator which outputs image light;

a first means for receiving image light from said image generator, said first means comprising fibers having a first diameter;

a second means for receiving image light output by said first means comprising a plurality of fibers having a diameter greater than said first diameter;

a fold mirror for receiving light output by said second means and reflecting said light in a first direction away from the eye of the user;

a reflector for receiving said image light transmitted in said first direction and redirecting said image light toward the eye of the user.

6. Apparatus as claimed in claim 5 wherein said reflector is a curved reflector defining a focus.

7. Apparatus as claimed in claim 5 wherein said fibers of said second means having a diameter between about six microns and about fifteen microns.

8. Apparatus as claimed in claim 5 wherein said first means is substantially in contact with said image generator.

9. Apparatus as claimed in claim 5 wherein said second means is substantially in contact with said first means.

10. Head-mounted display apparatus comprising:

an image generator;

a first plate positioned to receive image light from said image generator and having fiber optic means;

means for controlling the size of the energy window comprising a plurality of fibers adjacent said first plate wherein the diameter of said plurality of fibers is greater than the diameter of the fiber optic means in said first plate.