Terahertz imaging system for examining articles

• US 7,449,695 B2
• Filed: 05/26/2005
• Issued: 11/11/2008
• Est. Priority Date: 05/26/2004
• Status: Active Grant

• Current Assignee: Luna Innovations, Inc.
• Original Assignee: Picometrix LLC (Luna Innovations, Inc.)
• Inventors: Zimdars, David A., Williamson, Steven L., Stuk, Greg
• Primary Examiner(s): Porta; David P.
• Assistant Examiner(s): Igyarto; Carolyn
• Application Number:
  US11/138,246
• Publication Number:
  US 20070235658A1
• Time in Patent Office: 1,265 Days
• Field of Search: 250/390.07, 250/359.1, 250/341.7, 250/341.8
• US Class Current: 250/341.8
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/3586 by Terahertz time domain spectroscopy [THz-TDS]
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

A system to detect an article includes one or more terahertz modules. Each module either generates or receives, or both generates and receives, terahertz radiation. Some of the terahertz radiation is reflected from the article and the remainder of the terahertz radiation is transmitted through the article. A processor analyzes the reflected and transmitted terahertz radiation to characterize the article.

Claims

1. A system to detect an article comprising:

one for more terahertz modules, each module either generating or receiving, or both generating and receiving, terahertz radiation, some of the terahertz radiation being reflected from the article and the remainder of the terahertz radiation being transmitted through the article;

a processor configured to convert the transmitted and reflected terahertz radiation to a plurality of voxels, and assign each voxel of the plurality of voxels a location within a volume and a signature, wherein the signature indicates a material characteristic, and characterize the article based on the location of the plurality of voxels within the volume and the signatures of each voxel of the plurality of voxels; and

wherein the processor is further configured to determine if the article is an explosive device based on the location of the plurality of voxels within the volume and the signatures of each voxel of the plurality of voxels.

2. The system of claim 1 wherein the transmitted terahertz radiation is analyzed for spectral signatures of the article.

3. The system of claim 1 wherein the transmitted terahertz radiation is analyzed for attenuation of the transmitted radiation.

4. The system of claim 1 wherein the transmitted terahertz radiation is analyzed for the time delay of the transmitted radiation.

5. The system or claim 1 wherein the reflected terahertz radiation is reflected from at least one interface between the article and another material.

6. The system of claim 1 wherein the reflected terahertz radiation is analyzed for spectral signatures of the article.

7. The system of claim 1 wherein the reflected terahertz radiation is analyzed for the time delay of the reflected radiation.

8. The system of claim 1 wherein the reflected terahertz radiation is analyzed for the attenuation of the reflected radiation.

9. The system of claim 1 further comprising a source which produces optical pulses, at least one of said terahertz modules processing the optical purses to generate terahertz radiation.

10. The system of claim 1 further comprising a source which produces continuous wave optical radiation, at least one of said terahertz modules processing the continuous wave optical radiation to generate terahertz radiation.

11. The system of claim 1 wherein multiple terahertz modules are configured as a first array of terahertz modules.

12. The system of claim 11 further comprising a second array of terahertz modules, each module of the second array of terahertz modules either generating or receiving, or both generating and receiving, terahertz radiation.

13. The system of claim 1 wherein the processor is implemented with an algorithm that performs the analysis on the terahertz radiation information.

14. The system of claim 1 further comprising one or more other diagnostics to augment the terahertz radiation information analyzed by the processor.

15. The system of claim 14 wherein the other diagnostics is selected from the group consisting of mass spectrometry, X-ray, and metal detection.

16. The system of claim 1 wherein the processor analyzes the time-of-flight of the terahertz radiation and correlates the time-of-flight of the reflection radiation to obtain signatures unique to a component of the article.

17. The system of claim 1 wherein the terahertz modules operate in the range between about 0.01-10 THz.

18. The system of claim 1, wherein the processor is further configured to characterize the article by determining if the number of voxels located within the volume is above a threshold value.

19. The system of claim 1, wherein the processor is further configured to characterize the article by determining if the plurality of voxels are sufficiently contiguous within the volume.

20. A method to detect an article comprising:

generating or receiving, or both generating and receiving, terahertz radiation from One or more terahertz modules, some of the terahertz radiation being reflected from the article and the remainder of the terahertz radiation being transmitted through the article;

converting the transmitted and reflected terahertz radiation to a plurality of voxels,

assigning each voxel of the plurality of voxels a location within a volume and a signature, wherein the signature indicates a material characteristic;

characterizing the article based on the location of the plurality of voxels within the volume and the signatures of each voxel of the plurality of voxels; and

characterizing the article by determining if the article is an explosive device based on the location of the plurality of voxels within the volume and the signatures of each voxel of the plurality of voxels.

21. The method of claim 20 further comprising producing optical pulses, at least one of said terahertz modules processing the optical pulses to generate terahertz radiation.

22. The method of claim 20 further comprising producing continuous wave optical radiation, at least one of said terahertz modules processing the continuous wave optical radiation to generate terahertz radiation.

23. The method of claim 20 further comprising analyzing the time-of-flight of the terahertz radiation and correlating the time-of-flight of the reflection radiation to obtain signatures unique to a component of the article.

24. The method of claim 20 wherein the terahertz modules operate in the range between about 0.01-10 THz.

25. The method of claim 20, further comprising the step of characterizing the article by determining if the number of voxels located within the volume is above a threshold value.

26. The system of claim 20, wherein the processor is further configured to characterize the article by determining if the plurality of voxels are sufficiently contiguous within the volume.