Sol-gel tube crack detection apparatus and method

• US 20020121140A1
• Filed: 03/05/2001
• Published: 09/05/2002
• Est. Priority Date: 03/05/2001
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Lubecke, Victor M., Cadet, Gardy
• Granted Patent: US 6,612,172 B2
• Time in Patent Office: Days
• US Class Current: 73/587
• CPC Class Codes: G01S 13/50 Systems of measurement based on relative movement of target
• CPC Class Codes: G01S 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00

Abstract

A crack detection method capable of detecting cracks on a scale of about 5 μm or greater, useful for detecting cracks in sol-gel tubes. A signal is transmitted from a source to a body in which cracking may occur. The signal is reflected back to a sensor. An output voltage from the sensor is measured which is proportional to a signal characteristic change between the transmitted and received signals. Signal characteristics such as frequency, phase, and amplitude may be monitored. The signal characteristic change may result from one or more mechanisms selected from the group consisting of microscopic motion of the body, media transition and fluid movement.

Further disclosed is a crack detector comprising a signal source and a sensor wherein cracks are detected according to the method described above.

Claims

1. A crack detection method comprising:

transmitting from a source to a body a signal;

receiving by a sensor the signal reflected by the body;

measuring an output voltage from the sensor that is proportional to a signal characteristic change between the transmitted and received signals;

wherein the signal characteristic change results from one or more mechanisms selected from the group consisting of, microscopic motion of the body, media transition and fluid movement.

2. The crack detection method of claim 1 wherein the cracks are detected in a sol-gel body.

3. The crack detection method of claim 1 performed in the temperature range of about 600°

F. to about 1000°

F.

4. The crack detection method of claim 1 wherein motion is resolved on a scale of greater than about 5 μ

m.

5. The crack detection method of claim 4 wherein motion is resolved on a scale of about 5 μ

m to about 1 mm.

6. The crack detection method of claim 2 wherein the sol-gel body is a precursor to a fiber optic tube.

7. The crack detection method of claim 1 wherein the signal has a frequency in the range of about 1 GHz to about 20 GHz.

8. The crack detection method of claim 1 wherein cracks are detected as they occur.

9. The crack detection method of claim 1 wherein a single frequency is analyzed.

10. The crack detection method of claim 1 further comprising:

filtering the output signal; and

amplifying the output signal.

11. The crack detection method of claim 1 further comprising providing a visual display of the signal characteristic change.

12. The crack detection method of claim 1 further comprising providing notification of detected signal characteristic changes real-time computer threshold analysis.

14. The crack detector of claim 13 used to detect cracks in a sol-gel body.

15. A method for sol-gel body fabrication process development comprising:

providing a sol-gel process;

carrying out the process;

detecting in real time, cracking of the sol-gel body during the process thereby isolating one or more process steps causing the cracking; and

adjusting the one or more process steps until cracking is diminished;

wherein cracks are detected according to claim 1.

16. A method for sol-gel body fabrication process development comprising:

providing a sol-gel process;

carrying out the process;

detecting in real time, cracking of the sol-gel body during the process thereby isolating one or more process steps causing the cracking; and

adjusting the one or more process steps until cracking is diminished;

wherein cracks are detected according to claim 1.

17. A crack detector for use with a furnace comprising:

a plug positioned near an end of the furnace;

a door positioned at the end of the furnace closest to the plug;

a cover positioned over the door; and

an antenna positioned within the area defined by an inner surface of the cover to an outer surface of the plug;

wherein cracks are detected according to the method of claim 1.

13. A crack detector to detect cracks in a body, the detector comprising:

a signal source;

a sensor positioned to receive a signal from the source reflected by the body; and

wherein a crack is detected by transmitting from the source to the body a signal;

receiving by the sensor the signal reflected by the body;

measuring an output voltage from the sensor that is proportional to the signal characteristic change between the transmitted and received signals; and

wherein the signal characteristic change results from one or more mechanisms selected from the group consisting of, microscopic motion of the body, media transition and fluid movement.