Multiprism collimator

• US 4,350,410 A
• Filed: 10/08/1980
• Issued: 09/21/1982
• Est. Priority Date: 10/08/1980
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Minott, Peter O.
• Primary Examiner(s): Henry, Jon W.
• Application Number:
  US06/195,228
• Time in Patent Office: 713 Days
• Field of Search: 350/170, 350/286, 350/287, 350/169
• US Class Current: 359/640
• CPC Class Codes: G02B 27/106 for splitting or combining a plurality of identical beams or images, e.g. image replication
• CPC Class Codes: G02B 27/126 The splitting element being a prism or prismatic array, including systems based on total internal reflection
• CPC Class Codes: G02B 5/045 Prism arrays

Abstract

A special purpose optical collimator system which generates multiple collimated light beams, with precisely related angular separation of the beams. The system is comprised of a stack of relatively flat plate-like refracted prisms (10₁, 10₂ . . . 10₁₅) in the form of wedges, each having a specified angular deviation, mounted on top of one another in a fixture (44) which holds the wedges so that they are adapted to operate at minimum angular deviation and thus are relatively insensitive to rotational and angular charges. A collimated source of monochromatic light generated for example by a helium-neon laser (20) and a collimated beam expander (24, 30 and 54) provides a common incident beam (14) to the wedges whereupon a plurality of, for example, equally spaced emergent beams (12₁, 12₂ . . . 12₁₅) are provided.

Claims

1. A refractive optical system for producing multiple beams of light having predetermined angular separations comprising:

means (20, 24, 30,

     38) for providing a collimated beam of monochromatic light;

a plurality of optically refractive prisms (10₁ . . . 10₁₅) each providing a predetermined substantially constant angular deviation (δ

) between an incident (14) and emergent light beam (12), said prisms being arranged to receive as an incident beam said collimated beam and operable to provide a respective emergent output beam, said plurality of output beams (12₁ . . . 12₁₅) produced thereby defining a pattern of beams determined by the relative angular refractive deviation between said prisms; and

means (44) for mounting said prisms so that they are oriented with respect to said incident beam to provide substantially minimum angular deviation (δ

_m), thereby providing an arrangement which is relatively insensitive to translational and rotational changes.

2. The system as defined by claim 1 wherein said prisms (10₁ . . . 10₁₅) are arranged in a stack in said mounting means (44).

3. The system as defined by claim 2 wherein each prism (10) in said stack has a different angular deviation (δ

).

4. The system as defined by claim 1 wherein said prisms (10₁ . . . 10₁₅) are comprised of wedge prisms.

5. The system as defined by claim 4 wherein said wedge prisms (10₁ . . . 10₁₅) are arranged in a stack in said mounting means and are comprised of flat plate type prisms having relatively broad top and bottom faces (40, 42) and relatively thin side faces (16, 17, 18, 19) and wherein said incident beam is directed (14) to one of said side faces (16), said output beam emerges from another of said side faces (18), and said mounting means contacts at least one other side face (17 or 19).

6. The system as defined by claim 5 wherein mounting means (44) includes a pair of parallel side walls (46, 48) and said wedge prisms include a pair of parallel side faces (17, 19) in contact with said pair of parallel side walls, said parallel side faces additionally forming a predetermined angle (β

) with said one side face (16) whereby said minimum angle deviation (δ

_m) is provided when said mounting means is directed to said incident beam (14) so that side walls (46,

     48) are parallely aligned with said incident beam.

7. The system as defined by claim 6 wherein said wedge prisms (10₁ . . . 10₁₅) provide mutually different and substantially equal angular deviations (δ

) to provide a fan beam pattern.

8. The system as defined by claim 1 wherein said plurality of prisms (10₁ . . . 10₁₅) comprise a stack of relatively flat glass wedges mounted in said mounting means (44) so that said wedges are operating at a position of substantially minimum deviation (δ

_m).

9. The system as defined by claim 8 wherein said glass wedges (10₁ . . . 10₁₅) are comprised of low temperature coefficient glass to substantially eliminate the effects of temperature on angular deviation (δ

).

10. The system as defined by claim 1 and additionally including means (52) interposed between said means (20, 24, 30) providing said collimated light beam and said refractive means (10₁ . . . 10₁₅) to provide a respective input aperture therefor.

11. The system as defined by claim 10 wherein said plurality of prisms comprise a stack of wedge prisms (10₁ . . . 10₁₅) each having a respective elongated face (16) adapted to receive said incident beam (14), and

said interposed means (52) comprises a mask having a plurality of apertures (62) in the form of elongated slits positioned in front of said stack of wedge prisms to provide a discrete entrance pupil area for each prism in said stack.

12. The system as defined by claim 1 wherein said means for providing said collimated light beams includes a laser light source (20).

13. The system as defined by claim 12 wherein said means for providing said collimated light beam additionally includes beam expanding collimator apparatus (24, 30) focused on said laser light source.

14. The system as defined by claim 13 wherein said collimator apparatus includes spatial filter means (38).