Method and system to detect tampering of a closed chassis using a passive fiber optic sensor

• US 20070109123A1
• Filed: 11/14/2005
• Published: 05/17/2007
• Est. Priority Date: 11/14/2005
• Status: Active Grant

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: Honeywell International Inc.
• Inventors: Dalzell, William, Fleischman, Scott, Tucker, James
• Granted Patent: US 7,518,507 B2
• Time in Patent Office: Days
• US Class Current: 340/568.200
• CPC Class Codes: G08B 13/1481 with optical detection

Abstract

A passive optical anti-tamper system including one or more light pipes, one or more light detectors and an alarm. The light pipes each include an input end and an output end and are located within a chassis with the one or more light detectors. The one or more light detectors are optically coupled to the output ends of the one or more light pipes. The alarm is operable to transmit a tamper-event-warning signal if an increased light level is detected by at least one detector.

Claims

1. A passive optical anti-tamper system, the system comprising:

one or more light pipes each including an input end and an output end, the one or more light pipes located within a chassis;

one or more light detectors located within the chassis, the one or more light detectors optically coupled to the output ends of the one or more light pipes; and

an alarm in communication with the one or more detectors, wherein the alarm is operable to transmit a tamper-event-warning signal if an increased light level is detected by at least one detector.

2. The system of claim 1, the system further comprising:

a gel located at an interface between the one or more detectors and the respective output end of the one or more light pipes, the gel operable to increase an efficiency of the optical coupling.

3. The system of claim 1, wherein the one or more light pipes comprise a plurality of optical fibers.

4. The system of claim 3, wherein the output ends of the plurality of optical fibers are bundled to form a bundled-output end and wherein the input ends of the plurality of optical fibers are unbundled.

5. The system of claim 4, wherein the unbundled input ends of the plurality of optical fibers are splayed.

6. The system of claim 4, wherein the unbundled input ends of the plurality of optical fibers are fixed within the chassis to face in a plurality of directions.

7. The system of claim 3, wherein the output ends of the plurality of optical fibers are coupled to more than one detector, wherein the more than one detectors sense more than one range of wavelengths.

8. The system of claim 7, wherein the plurality of optical fibers are fixed on a board in the chassis and wherein the input ends of the plurality of optical fibers face in substantially the same direction.

9. The system of claim 1, wherein the one or more light detectors include one of an array of photosensitive elements, photosensitive pixels, a charge-coupled device, an array of photo-detectors, and combinations thereof.

10. The system of claim 1, further comprising:

an opaque layer overlying the one or more light detectors not covered by the output end of the one or more light pipes and portions of the one or more light detectors not covered by the output end of the one or more light pipes.

11. The system of claim 1, wherein each light pipe is fixed at the input end and is coupled to a respective light detector at the output end, wherein the fixed input ends face in a plurality of directions.

12. The system of claim 11, wherein the one or more light pipes comprise one of plastic optical fibers, multimode optical fibers, single mode optical fibers, graded index rods, flexible graded index rods, and combinations thereof.

13. The system of claim 1, wherein the one or more light pipes comprise one of plastic optical fibers, multimode optical fibers, single mode optical fibers, graded index rods, flexible graded index rods, and combinations thereof.

14. A method to manufacture, the method comprising:

positioning one or more light detectors within a chassis with components to be protected from a tampering event;

positioning a plurality of optical fibers within the chassis, wherein output ends of the optical fibers are optically coupled to the one or more light detectors; and

connecting an alarm in communication with the one or more detectors.

15. The method of claim 14, further comprising:

closing the chassis when the plurality of optical fibers and the one or more light detectors are positioned; and

calibrating the light level within the closed chassis.

16. A method to passively detect a tampering event within a closed chassis, the method comprising:

detecting an increase in light through at least one of a plurality of optical fibers within a chassis; and

generating a tamper-event-warning signal in response to the detecting of the increase in light.

17. The method of claim 16, wherein detecting an increase in light comprises:

optically coupling light generated external to the chassis at an input end of at least one optical fiber;

transmitting the coupled light through the at least one optical fiber responsive to the optical coupling; and

optically coupling the transmitted light to at least one light detector.

18. The method of claim 16, further comprising:

damaging at least a portion of components within the chassis responsive to generating the tamper-event-warning signal, wherein the damaged portion of the components are made at least one of inoperable and irretrievable.

19. The method of claim 16, further comprising:

transmitting the tamper-event-warning signal to an external system responsive to generating the tamper-event-warning signal.

20. The method of claim 16, further comprising:

calibrating one or more detectors for an ambient light level within the closed chassis wherein the detecting an increase in a light level includes detecting a light level greater than the ambient light level.

21. A passive optical anti-tamper system, the system comprising:

means for detecting an increased light level within a chassis in the event that a surface of the chassis is opened; and

means for generating a tamper-event warning signal responsive to the opening.

22. The system of claim 21, the system comprising:

means for transmitting the tamper-event-warning signal responsive to the generating.

23. The system of claim 21, the system comprising:

means for damaging at least a portion of components within the chassis responsive to the generating.