Claims
- 1. A system for measuring optical characteristics comprising:
a laser producing an excitation signal; a single-mode optical fiber coupled to the laser so that a coupled excitation signal is introduced into the optical fiber, wherein the coupled excitation signal is a continuous wave signal modulated at variable frequencies; a first detector positioned to receive radiation backscattered by the optical fiber in response to the coupled excitation signal.
- 2. The system of claim 1 further comprising an external modulator coupled between the laser and the optical fiber and operating to modulate the intensity of the excitation signal at a frequency that varies linearly from a first frequency to a second frequency over a first duration.
- 3. The system of claim 1, wherein the external modulator modulates the intensity of the excitation signal over a second duration immediately following the first duration at a frequency that varies linearly from the first frequency to the second frequency.
- 4. The system of claim 1 further comprising a laser driver coupled to the laser and operating to modulate the intensity of the excitation signal at a frequency that varies linearly from a first frequency to a second frequency over a first duration.
- 5. The system of claim 4, wherein the laser driver modulates the intensity of the excitation signal over a second duration immediately following the first duration at a frequency that varies linearly from the first frequency to the second frequency.
- 6. The system of claim 1, wherein the coupled excitation signal is modulated at a first discrete frequency for a first duration and modulated at a second discrete frequency, different from the first discrete frequency, for a second duration by an external modulator coupled between the laser and the optical fiber.
- 7. The system of claim 1, wherein the coupled excitation signal is modulated at a first discrete frequency for a first duration and modulated at a second discrete frequency, different from the first discrete frequency, for a second duration by a laser driver coupled to the laser.
- 8. The system of claim 1, further comprising a second detector positioned to receive radiation backscattered by the optical fiber in response to the coupled excitation signal and sensitive to a different spectrum of backscattered radiation frequencies than the first detector.
- 9. The system of claim 1, further comprising an analog to digital converter that converts the output of the first detector from analog to digital format
CROSS REFERENCE TO RELATED APPLICATION
[0001] This patent application is a divisional of, and claims priority to, commonly owned U.S. patent application Ser. No. 09/840,060, filed Apr. 23, 2001, entitled, “Method and System for Measuring Optical Scattering Charateristics,” by Leif Fredin, Robert Chin and William Hallidy, which will issue as U.S. Pat. No. 6,606,148 on Aug. 12, 2003, and which is incorporated herein by reference for all purposes.
Divisions (1)
|
Number |
Date |
Country |
Parent |
09840060 |
Apr 2001 |
US |
Child |
10636025 |
Aug 2003 |
US |