Highly accurate temperature sensor using two fiber Bragg gratings
First Claim
1. A fiber optic temperature sensor comprising a laser source emitting a laser beam, a first optical coupler arranged to divide the laser beam into a first beam path and a second beam path, a second optical coupler arranged to divide the first beam path to a third beam path and a fourth beam path, a third optical coupler arranged to divide the second beam path to a fifth beam path and a sixth beam path, first and second fiber Bragg gratings forming a temperature sensor, the first fiber Bragg grating connected to the third beam path and providing reflected light to the fourth beam path and the second fiber Bragg grating connected to the fifth beam path and providing reflected light to the sixth beam path, a first photodetector connected to the fourth beam path to detect spectrum changes with temperature of the first fiber Bragg grating from reflected light on the fourth beam path, a second photodetector connected to the sixth beam path to detect spectrum changes with temperature of the second fiber Bragg grating from reflected light on the sixth beam path, and a microprocessor connected to the first and second photodetectors to determine a temperature measurement based upon the detected spectrum changes from the first and second photodetectors.
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Abstract
A new highly accurate temperature sensor for biomedical applications is proposed in this invention. This sensor including two fiber Bragg gratings with different thermal coefficients can accurately measure temperature with little laser frequency stabilization. This invention improves the measurement resolution and accuracy. Such a sensor can be used to calibrate the other fiber biomedical sensors when those fiber sensors are packaged together.
53 Citations
20 Claims
- 1. A fiber optic temperature sensor comprising a laser source emitting a laser beam, a first optical coupler arranged to divide the laser beam into a first beam path and a second beam path, a second optical coupler arranged to divide the first beam path to a third beam path and a fourth beam path, a third optical coupler arranged to divide the second beam path to a fifth beam path and a sixth beam path, first and second fiber Bragg gratings forming a temperature sensor, the first fiber Bragg grating connected to the third beam path and providing reflected light to the fourth beam path and the second fiber Bragg grating connected to the fifth beam path and providing reflected light to the sixth beam path, a first photodetector connected to the fourth beam path to detect spectrum changes with temperature of the first fiber Bragg grating from reflected light on the fourth beam path, a second photodetector connected to the sixth beam path to detect spectrum changes with temperature of the second fiber Bragg grating from reflected light on the sixth beam path, and a microprocessor connected to the first and second photodetectors to determine a temperature measurement based upon the detected spectrum changes from the first and second photodetectors.
Specification