Thermal imaging device

• US 5,737,119 A
• Filed: 09/06/1995
• Issued: 04/07/1998
• Est. Priority Date: 09/06/1995
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Menard, Peter, Mladjan, Gary
• Primary Examiner(s): Dzerzynski, Paul M.
• Assistant Examiner(s): CHANG, AUDREY Y
• Application Number:
  US08/524,448
• Time in Patent Office: 944 Days
• Field of Search: 359/350, 359/353, 359/354, 359/695, 359/698, 359/403, 359/421, 359/701, 359/702, 359/703, 359/706, 359/819, 359/420, 359/432, 250/330, 250/331, 250/332, 250/333, 250/334
• US Class Current: 359/353
• CPC Class Codes: G02B 15/02 by changing, adding, or subtracting a part of the objective, e.g. convertible objective
• CPC Class Codes: G02B 23/12 with means for image conversion or intensification
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A thermal imaging device (10) receives thermal infrared radiation from a viewed scene and responsively provides a visible image replicating the viewed scene. The imaging device (10) has a main housing with an optical aperture (16) at which a lens assembly (12) is attached. The lens assembly (12) has a number of lenses (200, 204, 208, 212, 216) sequentially mounted within a cylindrical housing (146), and defining an optical axis (199). A field-of-view-change mechanism (228) allows a user to select a wide field of view or a narrow field of view. The field-of-view-change mechanism (228) includes a rotatable field-of-view (FOV) ring (226) which rotates a tumbler (210) with a pair of lenses (208, 212) mounted therein. The tumbler (210) is positioned between a first position providing a wide field of view and a second position providing a narrow field of view. A rack (236) cooperates with the FOV ring (226) and the tumbler (210) so that rotation of the FOV ring (226) about a first axis (199) rotates the tumbler about a second axis (210'"'"') perpendicular to the first axis (199). An optical alignment mechanism (254) releasably retains the tumbler (210) in the first and second positions so that optical axes (199'"'"', 248'"'"') of the tumbler are respectively aligned with the optical axis (199) of the lens assembly (12).

Claims

1. A thermal imaging device including a housing having an optical aperture for receiving thermal infrared radiation from a scene, and responsively providing a visible image replicating the scene, said thermal imaging device comprising:

a telescopic variable-power lens assembly cooperable with said imaging device at said optical aperture for conducting thermal infrared radiation from the scene to said thermal imaging device, said lens assembly including a lens housing passing the thermal infrared radiation from the scene along an optical axis to said imaging device, a movable member mounted within said lens housing, said movable member carrying at least one lens, in a first position of said movable member said at least one lens being in said optical axis so that the thermal infrared radiation passing to said imaging device passes through said at least one lens, and said movable member in a second position disposing said at least one lens out of said optical axis;

wherein said relatively movable member is configured as a tumbler member pivotally supported within said lens housing;

wherein said lens assembly includes a field-of-view ring rotatable about said optical axis of said lens housing, and actuating linkage structure extending between said field-of-view ring and said tumbler member for effecting pivoting movement of said tumbler member between first and second positions in response to respective opposite rotations of said field-of-view ring, said tumbler member aligning said first and second optical axes thereof with said optical axis of said lens housing in respective ones of said first and second positions.

2. The thermal imaging device of claim 1 wherein a substantially 30-degree rotation of said field-of-view ring pivots said tumbler member approximately 90 degrees between said first and second positions thereof.

3. The thermal imaging device of claim 1 wherein said actuating linkage structure includes:

a drive helix ring coupled to said field-of-view ring, rotational about said lens housing, and having an inner thread surface formed thereon;

a gear member drivingly mounted on said tumbler member; and

a rack member having a thread section engageable with said inner thread surface of said drive helix ring, and a rack gear section engaging with said gear member;

said lens housing supporting said rack member for axial relative movement, and rotationally supporting said tumbler member.

4. The thermal imaging device of claim 3 wherein said drive helix ring defines a serrate outer periphery surface, and said field-of-view ring defines a matching serrate inner periphery surface drivingly engageable with said serrate surface of said drive helix ring, said drive helix ring being concentrically mounted rotationally upon said lens housing and carrying said field-of-view ring.

5. The thermal imaging device of claim 3 wherein said field-of-view ring has at least one lever part projecting radially outwardly from an outer periphery thereof.

6. The thermal imaging device of claim 3, wherein said field-of-view ring includes a stop boss abutting a limiting key mounted to said lens housing to limit rotational movement of said field-of-view ring between respective first and said second positions therefor.

7. The thermal imaging device of claim 1 wherein:

said imaging device further includes a magnetically-responsive sensor, and said telescopic variable-power lens assembly further includes a magnetic member moving between respective first and second positions in response to movements of said movable member, said magnetic member affecting said magnetically-responsive sensor of said imaging device in only one of said first and second positions, thereby to indicate a field of view of said lens assembly to said imaging device.

8. The thermal imaging device of claim 1 wherein said movable member is associated with an optical alignment mechanism for releasably retaining said movable member in either one of said first and said second positions.

9. A thermal imaging device including a housing having an optical aperture for receiving thermal infrared radiation from a scene, and responsively providing a visible image replicating the scene, said thermal imaging device comprising:

a telescopic variable-power lens assembly cooperable with said imaging device at said optical aperture for conducting thermal infrared radiation from the scene to said thermal imaging device, said lens assembly including a lens housing passing the thermal infrared radiation from the scene along an optical axis to said imaging device, a movable member mounted within said lens housing, said movable member carrying at least one lens, in a first position of said movable member said at least one lens being in said optical axis so that the thermal infrared radiation passing to said imaging device passes through said at least one lens, and said movable member in a second position disposing said at least one lens out of said optical axis;

wherein said movable member is associated with an optical alignment mechanism for releasably retaining said movable member in either one of said first and said second positions;

wherein said optical alignment mechanism includes;

a pair of spaced spring rods mounted in said lens housing; and

a detent member operatively coupled with said movable member and positioned between said pair of spring rods;

said pair of spring rods applying a restraining and restoring force to said detent member.

10. The thermal imaging device of claim 9 wherein said detent member includes a pair of arcuate projections each engageable with a respective one of said pair of spring rods during movement of said moveable member between said first and said second positions.

11. A thermal imaging device including a main housing having an optical aperture, said thermal imaging device receiving thermal infrared radiation from a viewed scene through said optical aperture and responsively providing a visible image replicating the viewed scene, said thermal imaging device comprising:

a focusing lens assembly releasably attachable to said main housing at said optical aperture for receiving thermal infrared radiation from said viewed scene and for providing said infrared radiation to said thermal imaging device, said lens assembly including;

a housing through which said infrared radiation is passable;

a plurality of lenses mounted within said housing, said lenses defining an optical axis of said lens assembly; and

a field-of-view-change mechanism for selectively changing between a wide field of view and a narrow field of view, said field-of-view-change mechanism including;

a field-of-view (FOV) ring rotatably mounted on said housing, said FOV ring having a rotational axis;

a tumbler rotatably mounted within said housing, said tumbler having a rotational axis, said tumbler including at least one FOV lens mounted therewithin, said tumbler having a first optical axis and a second optical axis defined therethrough, said FOV lens being aligned with one of said first or said second optical axis, said first optical axis defining a first field of view and said second optical axis defining a second field of view, said tumbler being selectively positioned in a first position wherein a first optical axis is substantially aligned with said optical axis of said lens assembly and in a second position wherein a second optical axis is substantially aligned with said optical axis of said lens assembly; and

gearing coupled to said FOV ring and said tumbler, said gearing for translating rotational movement of said FOV ring about said rotational axis thereof to rotational movement of said tumbler about said rotational axis thereof.

12. A thermal imaging device including a main housing having an optical aperture, said thermal imaging device receiving thermal infrared radiation from a viewed scene through said optical aperture and responsively providing a visible image replicating the viewed scene, said thermal imaging device comprising:

a focusing lens assembly releasably attachable to said main housing at said optical aperture for receiving thermal infrared radiation from said viewed scene and for providing said infrared radiation to said thermal imaging device, said lens assembly including;

a housing through which said infrared radiation is passable;

a plurality of lenses mounted within said housing, said lenses defining an optical axis of said lens assembly; and

a field-of-view-change mechanism for selectively changing between a wide field of view and a narrow field of view, said field-of-view-change mechanism including;

a field-of-view (FOV) ring rotatably mounted on said housing, said FOV ring having a rotational axis;

a tumbler rotatably mounted within said housing, said tumbler having a rotational axis, said tumbler including at least one FOV lens mounted therewithin, said tumbler having a first optical axis and a second optical axis defined therethrough, said FOV lens being aligned with one of said first or said second optical axis, said first optical axis defining a first field of view and said second optical axis defining a second field of view, said tumbler being selectively positioned in a first position wherein a first optical axis is substantially aligned with said optical axis of said lens assembly and in a second position wherein a second optical axis is substantially aligned with said optical axis of said lens assembly; and

gearing coupled to said FOV ring and said tumbler, said gearing for translating rotational movement of said FOV ring about said rotational axis thereof to rotational movement of said tumbler about said rotational axis thereof;

wherein said rotational axis of said FOV ring is substantially perpendicular to said rotational axis of said tumbler.

13. The thermal imaging device of claim 12 wherein said first optical axis of said tumbler is substantially perpendicular to said second optical axis of said tumbler.

14. A variable-power telescopic lens assembly for use with a thermal imaging device, said thermal imaging device being adapted to receive thermal infrared radiation from a scene and responsively providing a visible image replicating the scene, said telescopic lens assembly comprising:

a lens housing passing thermal infrared radiation from the scene along an optical axis to the imaging device, a movable member mounted within said lens housing, said movable member carrying at least one lens, in a first position of said movable member said at least one lens being in said optical axis so that the thermal infrared radiation passing to the imaging device passes through said at least one lens, and said movable member in a second position disposing said at least one lens out of said optical axis;

wherein said relatively movable member is configured as a tumbler member pivotally supported within said lens housing;

wherein said lens assembly includes a field-of-view ring rotatable about said optical axis of said lens housing, and actuating linkage structure extending between said field-of-view ring and said tumbler member for effecting pivoting movement of said tumbler member between first and second positions in response to respective opposite rotations of said field-of-view ring, said tumbler member aligning said first and second optical axes thereof with said optical axis of said lens housing in respective ones of said first and second positions;

wherein said actuating linkage structure includes;

a drive helix ring coupled to said field-of-view ring, rotational about said lens housing, and having an inner thread surface formed thereon;

a gear member drivingly mounted on said tumbler member; and

a rack member having a thread section engageable with said inner thread surface of said drive helix ring, and a rack gear section engaging with said gear member;

said lens housing supporting said rack member for axial relative movement, and rotationally supporting said tumbler member.

15. The thermal imaging device of claim 14 wherein said drive helix ring defines a serrate outer periphery surface, and said field-of-view ring defines a matching serrate inner periphery surface drivingly engageable with said serrate surface of said drive helix ring, said drive helix ring being concentrically mounted rotationally upon said lens housing and carrying said field-of-view ring.

16. The thermal imaging device of claim 15 wherein said variable-power telescopic lens assembly further includes a magnetic member moving between respective first and second positions in response to movements of said movable member.