Method and light collection system for producing uniform arc image size

• US 5,966,250 A
• Filed: 11/30/1995
• Issued: 10/12/1999
• Est. Priority Date: 11/30/1995
• Status: Expired due to Fees

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Shimizu, Jeffrey A.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US08/565,699
• Time in Patent Office: 1,412 Days
• Field of Search: 359/364, 359/649, 359/651, 359/724, 359/727, 359/728, 362/268
• US Class Current: 359/727
• CPC Class Codes: G02B 17/0888 the corrector having at least one aspheric surface, e.g. Schmidt plates
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0047 for use with a light source G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005
• CPC Class Codes: G03B 21/20 Lamp housings

Abstract

A structure and method for a collection system for a projector includes a collector for reflecting light and a correcting mechanism for receiving the reflected light. The collector and the correcting mechanism, in combination, correct the light and output a light beam having a uniform image size.

Claims

1. A light projection system comprising

a source of arc light,

a reflector having an optical axis with a focal point on which said source is located, said reflector receiving light from said source at a collection angle relative to said optical axis and reflecting light from zones which are determined by said collection angle, and

a correcting refractor positioned on said axis to directly receive light reflected from said zones,

wherein said reflector and said correcting refractor are designed so that said correcting refractor directly outputs collimated light having a uniform size of arc image over all zones of said reflector.

2. A light projection system as in claim 1 wherein said reflector in combination with said correcting refractor satisfies ##EQU4## wherein Θ

is said collection angle, y(Θ

) is the distance from said optical axis of a light ray outputted from said refractor, s(Θ

) is the size of the arc image seen from the zone corresponding to angle Θ

, Θ

_min is the minimum collection angle where light can strike the reflector, and c is a proportionality constant.

3. A light projection system as in claim 2 wherein the light reflected from the reflector at Θ

_min, is reflected toward the optical axis so that y(Θ

_min) is minimized, whereby center obscuration caused by the light source is minimized.

4. A light projection system as in claim 1 wherein said source is a non-spherical source.

5. A light projection system as in claim 1 wherein said correcting refractor consists of a single lens element.

6. A light projection system as in claim 1 wherein said reflector is aspheric.

7. A light projection system comprising

a non-spherical source of arc light,

a reflector having an optical axis with a focal point on which said source is located, said reflector receiving light from said source at a collection angle relative to said optical axis and reflecting light from zones which are determined by said collection angle, and

a correcting refractor positioned on said optical axis to directly receive light reflected from said zones,

wherein said reflector and said correcting refractor are designed so that said correcting refractor directly outputs a uniform size of arc image over all zones of said reflector.

8. A light projection system as in claim 7 wherein said reflector and said correcting refractor are designed so that said correcting refractor outputs collimated light.

9. A light projection system as in claim 7 wherein said system forms an image of the source at a finite distance from said correcting refractor.

10. A light projection system as in claim 9 wherein the arc image is magnified according to m(Θ

)=dΘ

/d (sin Φ

), wherein Θ

is the collection angle, m is the magnification, and Φ

is the angle which a light beam from the refractor makes with the optical axis.

11. A light projection system as in claim 10 wherein ##EQU5## where Θ

_min is a minimum collection angle at which light will be reflected from the reflector,

Φ

is an angle between the light from the lens element and the optical axis, and Φ

(Θ

_min) is the angle Φ

of light from the reflector at Θ

_min, and

s(Θ

) is an apparent arc size as viewed from the zone corresponding to collection angle Θ

.

12. A light projection system as in claim 7 wherein said correcting refractor consists of a single lens element.

13. A light projection system as in claim 7 wherein said reflector is aspheric.