Remote Optical Sensing of the Integrity of a Structure Using Reflected or Scattered Light

• US 20140211207A1
• Filed: 01/22/2014
• Published: 07/31/2014
• Est. Priority Date: 01/29/2013
• Status: Active Grant

• Current Assignee: Spectral Sciences, Inc.
• Original Assignee: Spectral Sciences, Inc.
• Inventors: Clark, Frank Oliver
• Granted Patent: US 9,442,002 B2
• Time in Patent Office: Days
• US Class Current: 356/369
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: G01H 9/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
• CPC Class Codes: G01M 11/081 by using a contact-less detection method, i.e. with a camera
• CPC Class Codes: G01M 5/0066 by exciting or detecting vibration or acceleration vibration testing of structures G01M7/00
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection

Abstract

A method and device for remotely detecting structural integrity using reflections or scattering from windows or other portions of a structure. The long geometrical lever arm of a reflection on a building window, when viewed with suitable instruments, produces detectable modulation in the reflected light from minute vibrational changes upon the glass surface, revealing fundamental resonances and structural changes and failure in the building housing the window. By sensing very small changes in intensity and polarization, information may be obtained on fundamental resonances and structural changes, including failure or imminent failure of the structure.

Claims

1. A method for non-contact sensing of the integrity of a structure, comprising:

remotely detecting light that has been reflected off of or scattered from the structure; and

analyzing the detected light to determine the structural integrity of the structure.

2. The method of claim 1 wherein the analyzing step comprises determining the intensity and polarization of detected ambient light.

3. The method of claim 2 wherein one or more polarization filters are used to filter the reflected light before it is analyzed.

4. The method of claim 3 wherein the analyzing step further comprises resolving one or more peaks in the power spectrum of the detected light.

5. The method of claim 4 wherein resolving one or more peaks in the power spectrum of the detected light comprises determining the frequency of the peaks.

6. The method of claim 1 wherein the light is detected over time, and the analyses thereof are stored, wherein stored analyses are compared.

7. The method of claim 6 wherein the comparisons are used to detect gradual structural changes in the structure.

8. The method of claim 1 wherein the structure is scanned so as to survey different areas of the structure.

9. The method of claim 8 wherein the analyzing step comprises creating a pixel-by-pixel frequency map of the scanned areas.

10. The method of claim 1 further comprising actively illuminating the structure with polarized light so as to enhance the results.

11. The method of claim 1 wherein the analyzing step comprises determining whether there is a fire in the building.

12. The method of claim 11 wherein the detected light is analyzed for characteristic acoustic emanations of a fire.

13. The method of claim 11 wherein the detected light is analyzed for frequency content indicative of fire and/or the extent and size of a fire.

14. The method of claim 11 wherein the magnitude of sensed building vibrations is indicative of the location of the fire.

15. The method of claim 14 wherein the fire is located close to the location of the greatest magnitude vibrations.

16. The method of claim 11 wherein the detected light is analyzed for high frequency cutoff indicative of a volume of the fire.

17. The method of claim 1 wherein the analyzing step comprises determining whether the building structure has degraded.

18. The method of claim 17 wherein the detected light is analyzed for changes in damping of vibration by the building structure.

19. The method of claim 18 wherein a decrease in damping is equated with structural degradation.

20. The method of claim 19 wherein the detected light is analyzed for frequency content indicative of structural degradation.