# US 5,347,391 A · Ultra wide field of view scanning surveillance optical system

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- Number: US 5,347,391 A
- Document ID: US5347391A
- Status: Granted
- Kind: A
- Application number: 07/992,398
- Filed: 1992-12-18
- Granted: 1994-09-13
- Earliest claimed: 1992-12-18
- Assignees: Hughes Aircraft Company
- Inventors: Lacy G. Cook; Bryce A. Wheeler
- Web page: https://patentgrep.com/patent/US5347391A

## CPC

- G02B 27/642: {Optical derotators, i.e. systems for compensating for image rotation, e.g. using rotating prisms, mirrors}
- G02B 13/04: Reversed telephoto objectives
- G02B 13/14: for use with infrared or ultraviolet radiation ({G02B13/008, } G02B13/16 take precedence)
- G02B 17/045: {having static image erecting or reversing properties only (optical derotators G02B27/642; optical devices for controlling the direction of light using movable or deformable optical elements G02B26/08)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A refractive inverse telephoto optical system (10) has a first lens doublet (12), a Pechan prism assembly (14) and a second lens doublet (16). The Pechan prism assembly (14) is spaced between the front negative doublet (12) and the rear positive doublet (16). The Pechan prism assembly (14) may be rotated and, as rotation occurs, the associated linear detector array is rotated around within the optical field of view.

## Claims

### Claim 1

A refractive optical system comprising:
first lens means for receiving light from a scene;
prism means for redirecting said light, said prism means including a singlet lens and being positioned to receive light from said first lens means, said prism means enabling scanning of an ultra wide field of view of said scene;
second lens means for focusing said light on a viewing plane, said second lens means positioned to receive light from said prism means such that said ultra wide field of view of said scene is focused on a detection plane.

### Claim 2 (depends on 1)

The refractive optical system as set forth in claim 1, wherein said "ultra-wide" field of view is greater than 110.degree..

### Claim 3 (depends on 1)

The refractive optical system as set forth in claim 1, wherein said first lens means is a negative power lens doublet.

### Claim 4 (depends on 1)

The refractive optical system as set forth in claim 1, wherein said second lens means is a positive power lens doublet.

### Claim 5

A refractive optical system comprising:
a first lens doublet for receiving light from a scene;
a Pechan prism assembly for receiving and redirecting said light from said first lens doublet, said Pechan prism assembly including a lens positioned to receive light between halves of said Pechan prism and providing scanning of an ultra wide field of view of said scene to be viewed; and
a second lens doublet for receiving light from said Pechan prism and focusing said light on a detection plane such that said ultra wide field of view may be detected at said detection plane.

### Claim 6 (depends on 5)

The refractive optical system as set forth in claim 5, wherein said first doublet has a negative power.

### Claim 7 (depends on 5)

The refractive optical system as set forth in claim 5, wherein said second doublet has a positive power.

### Claim 8 (depends on 5)

The refractive optical system as set forth in claim 5, wherein said Pechan prism assembly is rotatable.

### Claim 9 (depends on 5)

The refractive optical system as set forth in claim 5, wherein a system aperture stop is located between two Pechan prism halves.

### Claim 10

A refractive inverse telephoto optical system comprising:
a first negative power lens doublet for receiving light from a scene;
a Pechan prism for receiving and redirecting said light from said first lens doublet, said Pechan prism providing scanning of an ultra wide field of view of said scene to be viewed;
a singlet lens positioned to receive light between halves of said Pechan prism; and
a second positive power lens doublet for receiving light from said Pechan prism and focusing said light on a detection plane such that said ultra wide field of view may be detected at said detection plane.

### Claim 11 (depends on 10)

The refractive inverse telephoto optical system as set forth in claim 10, wherein said Pechan prism assembly is rotatable.

### Claim 12 (depends on 10)

The refractive inverse telephoto optical system as set forth in claim 10, wherein a system aperture stop is located between two Pechan prism halves.

### Claim 13 (depends on 10)

The refractive inverse telephoto optical system as set forth in claim 10, wherein said lenses of said first doublet are silicon lenses and both have negative power.

### Claim 14 (depends on 10)

The refractive inverse telephoto optical system as set forth in claim 10, wherein said Pechan prism is made of silicon.

### Claim 15 (depends on 10)

The refractive inverse telephoto optical system as set forth in claim 10, wherein said lenses of said second doublet are germanium lenses and both have positive power.

### Claim 16 (depends on 10)

The refractive inverse telephoto optical system as set forth in claim 10, wherein said singlet lens is a silicon positive power lens.