# US 5,706,137 A · Wide field of view imaging system

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- Number: US 5,706,137 A
- Document ID: US5706137A
- Status: Granted
- Kind: A
- Application number: 08/284,845
- Filed: 1994-08-02
- Granted: 1998-01-06
- Earliest claimed: 1992-09-22
- Inventors: Shawn L. Kelly
- Web page: https://patentgrep.com/patent/US5706137A

## CPC

- G02B 27/46: Systems using spatial filters
- G02B 27/0025: {for optical correction, e.g. distorsion, aberration}
- G02B 27/0172: {characterised by optical features}
- G09B 9/307: {by helmet-mounted projector or display (G09B9/36 takes precedence; optical parts of head-up displays G02B27/01)}
- G02B 27/017: {Head mounted}
- G02B 2027/011: {comprising device for correcting geometrical aberrations, distortion}
- G02B 2027/012: {comprising devices for attenuating parasitic image effects}
- G02B 2027/0123: {comprising devices increasing the field of view}
- G02B 2027/0127: {comprising devices increasing the depth of field}
- G02B 2027/0143: {the two eyes not being equipped with identical nor symmetrical optical devices}
- G02B 2027/0152: {involving arrangement aiming to get lighter or better balanced devices}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G09B: EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS (devices for psychotechnics or for testing reaction times A61B5/16; games, sports, amusements A63; projectors, projector screens G03B)

## Abstract

A wide FOV imaging system (10) includes an objective lens (14), a convergent reflective element (18) positioned proximate an intermediate image (16) formed by the objective lens, and a re-imaging lens (20) for re-imaging the intermediate image. The present invention significantly improves image fidelity while minimizing optical components by utilizing a convergent reflective element proximate the intermediate image to reverse the propagation of aberrations produced by the objective lens (14) to, as a result, significantly cancel or reduce the aberrations contributed by the re-imaging lens.

## Claims

### Claim 1

An optical imaging system comprising:
an object imaging means for forming an intermediate image of an object image, said object imaging means producing particular aberrations in the intermediate image;
means for reversing at least some of the aberrations in the intermediate image comprising a convergent reflective medium positioned proximate the intermediate image; and
a re-imaging means for re-imaging the intermediate image reflected by said reflective medium, said re-imaging means producing image aberrations similar to the aberrations produced by said object imaging means, thereby substantially cancelling the aberrations reversed by said reversing means in the re-imaged intermediate image.

### Claim 2 (depends on 1)

The system of claim 1 wherein said convergent reflective medium comprises a concave mirror.

### Claim 3 (depends on 2)

The system of claim 2 wherein said concave mirror further comprises a Fresnel structure formed on the mirror surface.

### Claim 4 (depends on 2)

The system of claim 2 wherein said concave mirror further comprises a concave mirror substrate having a front surface and a back surface provided with a reflective coating, wherein said mirror substrate corrects optical aberrations in said intermediate image produced by said object imaging means, and precorrects for optical aberrations produced by said re-imaging means after said intermediate image is reflected by said reflective coating.

### Claim 5 (depends on 1)

The system of claim 1 wherein said convergent reflective medium comprises a flat Fresnel mirror.

### Claim 6 (depends on 1)

The system of claim 1 further comprising a beam splitter positioned between said object imaging means and said reflective surface for imaging the intermediate image reflected by said reflective medium to said re-imaging means.

### Claim 7 (depends on 1)

The system of claim 1 wherein said means for forming an intermediate image comprises a projection means which produces a modulated scanning light beam to form the intermediate image, and said convergent reflective medium comprises a concave projection screen positioned substantially at the intermediate image.

### Claim 8 (depends on 7)

The system of claim 7 wherein the light forming said intermediate image has a predetermined cone of incidence, and said concave projection screen comprises means for redistributing the light incident on any point of the screen surface into a cone of exodus larger than said cone of incidence.

### Claim 9 (depends on 1)

The system of claim 1 wherein the light forming said intermediate image has a predetermined cone of incidence, and said means for reversing further comprises means for redistributing the light incident on any point of said convergent reflective medium into a cone of exodus larger than said cone of incidence.