Systems and methods for non-destructively detecting material abnormalities beneath a coated surface

• US 20050098728A1
• Filed: 09/24/2004
• Published: 05/12/2005
• Est. Priority Date: 09/25/2003
• Status: Active Grant

• Current Assignee: Baolong Yu, Robert R. Alfano
• Original Assignee: Baolong Yu, Robert R. Alfano
• Inventors: Alfano, Robert R., Yu, Baolong
• Granted Patent: US 7,145,148 B2
• Time in Patent Office: Days
• US Class Current: 250/341.8
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: G01N 21/8422 Investigating thin films, e.g. matrix isolation method

Abstract

The present invention provides systems and methods for non-destructively detecting material abnormalities beneath a coated surface. A terahertz (THz) illumination unit illuminates an area of the coated surface. A detection unit detects light reflected from the illuminated area of the coated surface, and a processing unit images the illuminated area of the coated surface from optical characteristics received from the detection unit.

Claims

1. A system for non-destructively detecting material abnormalities beneath a coated surface, comprising:

a terahertz (THz) illumination unit for illuminating an area of the coated surface;

a detection unit for detecting light reflected from the illuminated area of the coated surface; and

a processing unit for imaging the illuminated area of the coated surface.

2. The system as recited in claim 1, wherein the THz illumination unit comprises:

at least one THz light source; and

at least one reflector for reflecting and concentrating light from the light source on the illuminated area of the coated surface.

3. The system as recited in claim 2, wherein the at least one THz light source is at least one of a femtosecond, picosecond, and nanosecond laser.

4. The system as recited in claim 2, wherein at least one reflector is a mirror.

5. The system as recited in claim 2, further comprising at least one nonlinear crystal to produce THz radiation.

6. The system as recited in claim 2, wherein the at least one THz light source comprises one of a fast switch and a quantum well semiconductor device.

7. The system as recited in claim 1, further comprising a scanning unit for moving the THz illumination unit and the detection unit to a next area of the coated surface.

8. The system as recited in claim 7, wherein the scanning unit comprises a means for moving the system in at least one of X and Y directions.

9. The system as recited in claim 1, wherein the detection unit comprises:

a balanced detector for detecting the reflected light from the illuminated area of the coated surface, and producing detected signal information; and

at least one reflector for reflecting and concentrating the reflected light from the illuminated area of the coated surface to the balanced detector.

10. The system as recited in claim 1, wherein the processing unit comprises:

a lock-in amplifier for processing signals received from the detection unit; and

a computer for digitizing and storing the processed signals to produce a 2-D image by translation and scanning.

11. The system as recited in claim 1, wherein the surface is metal.

12. The system as recited in claim 1, wherein the coating is one of a paint, and a primer.

13. The system as recited in claim 1, wherein the material abnormalities include at least one of deterioration, corrosion, and cracking regions.

14. A method for non-destructively detecting material abnormalities beneath a coated surface, comprising the steps of:

illuminating an area of a coated surface by a terahertz (THz) light source;

detecting light reflected from the illuminated area of the coated surface; and

imaging the surface below the illuminated area of the coated surface.

15. The method as recited in claim 14, further comprising displaying a 2-D image on a display.

16. The method as recited in claim 14, further comprising imaging a next area of the coated surface.

17. The method as recited in claim 16, wherein the step of imaging the next area comprises moving the THz light source and a THz detection unit in at least one of X and Y directions.

18. The method as recited in claim 14, wherein the surface is metal.

19. The method as recited in claim 14, wherein the coating is one of a paint and a primer.

20. The method as recited in claim 14, wherein the abnormalities include at least one of deterioration, corrosion, and cracking areas.