Planar fiber-optic interferometric acoustic sensor
First Claim
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1. A sensing portion for an interferometric acousto-optic sensor portion, comprising:
- a concentrically wound or snaked sensor fiber having a solid light-transmitting core and a clad layer surrounding said core; and
a layer of a material within which said sensor fiber is embedded, said material having a bulk modulus of no greater than about 5(1010) dyn/cm2 at 1 MHz at its ambient temperature of use, said layer being sufficiently thick to significantly increase the pressure sensitivity of said fiber within a frequency range of about 250-2500 Hz.
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Abstract
A sensing portion for an interferometric acousto-optic sensor and a sensor using that sensing fiber are disclosed. The sensor fiber has an outer coating of a material having a low bulk modulus. This coating greatly enhances the sensitivity of the sensor fiber. In a preferred embodiment, the material of low bulk modulus embeds the sensor fiber and any included reference fiber. Most preferably, the material having a low bulk modulus is a polymer such as polyurethane. The sensing portions made according to the present invention will usually be incorporated into sensors used for underwater exploration.
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14 Claims
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1. A sensing portion for an interferometric acousto-optic sensor portion, comprising:
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a concentrically wound or snaked sensor fiber having a solid light-transmitting core and a clad layer surrounding said core; and a layer of a material within which said sensor fiber is embedded, said material having a bulk modulus of no greater than about 5(1010) dyn/cm2 at 1 MHz at its ambient temperature of use, said layer being sufficiently thick to significantly increase the pressure sensitivity of said fiber within a frequency range of about 250-2500 Hz. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An acousto-optic interferometric sensor comprising:
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a light source; a detector; a sensing portion including;
a concentrically wound or snaked sensor fiber having a solid light-transmitting core and a clad layer surrounding said core; and
a layer of a material within which said sensor fiber is embedded, said material having a bulk modulus of no greater than about 5(1010) dyn/cm2 at 1 MHz at its ambient temperature of use, said layer being sufficiently thick to significantly increase the pressure sensitivity of said fiber within a frequency range of about 250-2500 Hz;a first lead fiber extending between said light source and said sensing portion; and a second lead fiber extending between said sensing portion and said detector. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification