Surveillance system having a microchannel image intensifier tube

• US 5,373,320 A
• Filed: 05/18/1993
• Issued: 12/13/1994
• Est. Priority Date: 05/18/1993
• Status: Expired due to Term

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Intevac
• Inventors: Daley, Thomas, Johnson, David B., Scott, Allan W.
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): LENCHAK, EMIL
• Application Number:
  US08/063,233
• Time in Patent Office: 574 Days
• Field of Search: 358/108, 358/225, 358/226, 358/227, 358/228, 348/216, 348/217, 348/360, 348/361, 348/335
• US Class Current: 348/217.1
• CPC Class Codes: G08B 13/19619 Details of casing
• CPC Class Codes: G08B 13/19626 optical details, e.g. lenses, mirrors or multiple lenses
• CPC Class Codes: G08B 13/19634 Electrical details of the system, e.g. component blocks for carrying out specific functions
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules

Abstract

A camera attachment converts a standard day-light video camera into a day/night-vision video camera. The attachment device has a threaded input and output to physically and optically interconnect an auto-iris lens to a video camera. The attachment device contains an image intensifier tube and a fiber optic image conduit either of which may be switched into the through optical path to receive and either amplify or simply conduct the light image to a relay lens. The relay lens focuses the output image from either the image tube or the fiber optic image conduit onto the optical input of the video camera. The switching of the image intensifier tube or the fiber optic image conduit is dependent upon the ambient light conditions of the camera so that if there is insufficient lighting for normal daytime viewing the image tube is activated and switched into the through optical path of the camera.

Claims

1. An image intensifier surveillance camera system having a single optical path for operation in daytime and night-time lighting conditions without additional illumination, said image intensifier surveillance camera system comprising:

an iris lens for receiving incoming light representing a light image, means to regulate the iris lens opening based on the intensity of the incoming light;

a surveillance camera in a fixed position relative to said iris lens and coupled to said iris lens; and

an image intensifier assembly comprising an image intensifier tube and an optical path length compensator to present an image corresponding to the input image without inversion and means to position said image intensifier tube or said optical path length compensator in the optical path between said iris lens and said surveillance camera at the camera focal plane.

2. An image intensifier surveillance camera system in accordance with claim 1 in which said optical path length compensator comprises a fiber optic plate.

3. An image intensifier surveillance camera system in accordance with claim 1 in which said optical path length compensator comprises a non-inverting lens.

4. An image intensifier surveillance camera system in accordance with claim 3 wherein said image intensifier assembly includes an image intensifier tube having a feedback limiting microchannal plate including a metalization layer at the output surface thereof.

5. An image intensifier surveillance camera system in accordance with claim 1 wherein said image intensifier assembly comprises:

a rotatable disc having mounted thereon said image intensifier tube and said optical path length compensator for rotation of one of said image intensifier tube or said optical path length compensator into the optical path of an incoming image.

6. An image intensifier surveillance camera system in accordance with claim 5 wherein said rotatable disc rotates in response to camera control means controlled by the incoming light intensity.

7. An image intensifier surveillance camera system in accordance with claim 2 in which said surveillance camera comprises a CCD video camera.

8. An image intensifier surveillance camera system in accordance with claim 5 further comprising:

a housing for said rotatable disc, said housing having a threaded input and threaded output for coupling the output of said iris lens to said image intensifier assembly and for coupling said image intensifier assembly to said surveillance camera.

9. An image intensifier surveillance camera system in accordance with claim 8 including means to position said optical path length compensator in the optical path length from said iris lens to said camera during daytime lighting conditions of said camera system.

10. An image intensifier surveillance camera system in accordance with claim 8 including means to position said image intensifier tube in the optical path length from said iris lens to said surveillance camera during night-time lighting conditions of said image intensifier surveillance camera system.

11. An attachment for converting a day surveillance camera with an auto-iris assembly to a day/night camera to operate under night-time ambient lighting conditions without additional illumination, said attachment comprising:

a housing having a threaded input and threaded output for optically interconnecting said auto-iris assembly to a camera;

an image intensifier tube;

an optical path length compensator having the same optical path length as said image intensifier tube for presenting an image without inversion at the output end of said optical path length compensator; and

means for switching in response to ambient light conditions either said image intensifier tube or said optical path length compensator into optical alignment with said auto-iris assembly and said camera, said image intensifier tube intended for operation under night-time conditions to intensify light images transmitted to said camera and said optical path length compensator intended for operation under daytime conditions to transmit daylight images to said camera.

12. An attachment in accordance with claim 11 further comprising a disc rotatably connected to said housing and containing said image intensifier tube and said optical path length compensator, said disc for automatically rotating in response to said ambient lighting conditions either said image intersifier tube or said compensator into optical alignment with said auto-iris assembly and said camera.

13. An attachment in accordance with claim 12 wherein said optical path length compensator comprises a fiber optics plate.

14. An attachment in accordance with claim 11 wherein said threaded input and threaded output further comprise C-mount connections.

15. An attachment in accordance with claim 14 wherein said image intensifier tube is electrically inactivated so long as said optical path length compensator is positioned to receive light images from said auto-iris assembly in the optical path to said camera.

17. An attachment in accordance with claim 11 further including a power supply within said housing.

16. A method of performing surveillance at night and during the day with the same security camera system comprising automatically cycling an image intensifier tube to intensify night-time images into an image optical path feeding to said same security camera system and automatically cycling said image intensifier tube out of said image optical path and an optical path length compensator which does not invert into said image optical path during daytime operation.