Multiplexed fiber optic sensor system

• US 7,379,630 B2
• Filed: 10/07/2005
• Issued: 05/27/2008
• Est. Priority Date: 05/28/2002
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Lagakos, Nicholas, Bucaro, Joseph A
• Primary Examiner(s): Font; Frank G.
• Assistant Examiner(s): WONG, ERIC K
• Application Number:
  US11/250,709
• Publication Number:
  US 20060072888A1
• Time in Patent Office: 963 Days
• Field of Search: 385/12, 385/13, 385/115
• US Class Current: 385/12
• CPC Class Codes: G01L 7/086 with optical transmitting or indicating means
• CPC Class Codes: G01L 9/0077 for measuring reflected light
• CPC Class Codes: G01P 15/093 by photoelectric pick-up
• CPC Class Codes: G02B 2006/12138 Sensor
• CPC Class Codes: G02B 6/06 the relative position of the fibres being the same at both ends, e.g. for transporting images
• CPC Class Codes: G02B 6/2817 using reflective elements to split or combine optical signals
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3558 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/3594 Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams

Abstract

A multiplexed fiber optic sensor system including a first optical fiber having a first end arranged to receive light from a light souce, at least two optical fibers having diameters smaller than the first optical fiber, and at least two fiber optic sensors, each of the at least two smaller diameter optical fibers arranged between the first optical fiber and one of the sensors for transmitting light from the first optical fiber to that sensor. The sensors can be static or dynamic pressure sensors, strain sensors, temperature sensors or other environmental sensors.

Claims

1. A fiber optic sensor system comprising:

a first optical fiber having a first end arranged to receive light from a light source and a second end arranged to transmit light out of the first optical fiber;

at least two optical fibers having diameters smaller than the first optical fiber; and

at least two fiber optic sensors;

each of the at least two smaller diameter optical fibers arranged between the first optical fiber and one of the sensors for transmitting light from the first optical fiber to that sensor,

and the at least two smaller diameter fibers have ends that face toward the second end of the first optical fiber, such that each of the two smaller diameter fibers receive a portion of the light from the first optical fiber and transmit the light portion to one of the two sensors.

2. A fiber optic sensor system according to claim 1, further comprising:

the light source.

3. The sensor system according to claim 2, wherein the light source is an LED.

4. The sensor system according to claim 1, wherein a light intensity variation between the smaller diameter fibers is less than 10%.

5. The sensor system according to claim 1, wherein the fiber optic sensors are static or dynamic pressure sensors or strain sensors.

6. The sensor system according to claim 1, further comprising:

at least one photodetector arranged to convert light from the sensor into an electrical signal; and

at least one optical fiber arranged between each sensor and each photodetector.

7. The sensor according to claim 1, further comprising:

at least one photodetector ananged to convert light from the sensor into an electrical signal;

a plurality of optical fibers arranged to receive light from the sensor;

an optical fiber having a diameter larger than the optical fibers ananged to receive light from the sensor, said larger diameter optical having an end abutting ends of the smaller diameter optical fibers.

8. The sensor according to claim 1, wherein each fiber optic sensor further includes a fiber bundle including a transmitting fiber and at least one receiving fiber, a reflective flexible membrane arranged at one end of the fiber bundle for reflecting light from the transmitting fiber into the receiving fiber, the reflective flexible membrane held at a distance from the one end of fiber bundle by a housing that extends beyond the end of the fiber bundle.

9. The fiber optic static pressure sensor according to claim 8, wherein the fiber bundle has six receiving fibers surrounding the transmitting fiber for receiving light reflected by the membrane.

10. A fiber optic system comprising:

a plurality of optical fibers for transmitting light from a sensor to a photodetector, each optical fiber having a diameter,

an optical fiber having a diameter larger than the plurality of optical fibers,

the larger diameter optical fiber arranged abutting against the plurality of optical fibers to receive light from the plurality of optical fibers, and

a photodetector ananged to receive the light from the larger diameter optical fiber.

11. The fiber optic system according to claim 10, wherein the larger diameter optical fiber has a core diameter at least twice as large the core diameters of the receiving fibers.

12. The fiber optic system according to claim 10, wherein the plurality of optical fibers includes six optical fibers.

13. The fiber optic system according to claim 10, wherein the plurality of optical fibers includes three optical fibers.

14. The fiber optic system according to claim 10, further comprising:

the sensor.

15. A method of sensing pressure with a plurality of fiber optic sensors, the method comprising:

transmitting light through a first optical fiber, the first optical fiber having a first end arranged to receive light from a light source and a second end arranged to transmit light out of the first optical fiber;

a plurality of optical fibers having a diameter smaller than the first optical fiber receiving light from the first optical fiber, and the plurality of optical fibers have ends that face toward the second end of the first optical fiber, such that each of the two smaller diameter fibers receive a portion of the light from the first optical fiber and transmit the light portion to one of the sensors;

each of the sensors sensing an environmental condition and further transmitting a portion of the light to a photodetector, an amount of light received by the photodetectors being indicative of the sensed environmental condition.

16. The method according to claim 15, wherein the sensors are at least one of pressure sensors, strain sensors, dynamic pressure sensors, strain sensors, displacement sensors, acceleration sensors, temperature sensors, and bio-chemical sensors.

17. The method according to claim 15, wherein the sensors are pressure sensors.