Claims
- 1. An apparatus for conditioning the output signal of an optical fiber sensor having a first optical sensing fiber and a second optical reference fiber with both fibers being connected to a light source for supplying light of equal intensity therethrough, comprising:
- a first light sensing means connected to said optical sensing fiber for measuring changes in light intensity transmitted therethrough;
- a second light sensing means connected to said optical reference fiber for measuring changes in light intensity transmitted therethrough;
- means for determining a logarithm light intensity ratio connected to said first and second light sensing means which receives the measured light intensities therefrom; and
- scaling means connected to said logarithm light intensity ratio determining means for scaling the logarithm of the light intensity ratio to provide a scaled measurement of the output signal.
- 2. An apparatus as defined in claim 1, wherein said first and second light sensing means are a first and a second photodiodes.
- 3. An apparatus as defined in claim 2, wherein said logarithm light intensity ratio determining means comprises:
- a first amplifier with a positive and negative input connected to said first photodiode at the negative input;
- a second amplifier with a positive and a negative input connected to said second photodiode at the negative input; and
- a difference unit connected to both of said first and second amplifiers for providing an output which is the logarithm light intensity ratio.
- 4. An apparatus as defined in claim 1, wherein said scaling means includes an output buffer amplifier having a coarse and fine adjusting means for providing a scaled measurement.
- 5. An apparatus as defined in claim 4, wherein said adjusting means are potentiometers.
Parent Case Info
This is a division of application Ser. No. 07/146,052 filed 1/20/88 and now U.S. Pat. No. 4,860,586 issued Aug. 29, 1989.
US Referenced Citations (4)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0027540 |
Apr 1981 |
EPX |
61-239129 |
Oct 1986 |
JPX |
WO7900377 |
Jun 1979 |
WOX |
2125161 |
Feb 1984 |
GBX |
Non-Patent Literature Citations (1)
Entry |
Davis, "An Introduction to Fiberoptic Sensors", Laser Focus 2/82, pp. 112-115. |
Divisions (1)
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Number |
Date |
Country |
Parent |
146052 |
Jan 1988 |
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