Optical fiber grating based sensor
First Claim
1. An optical sensor, comprising:
- a magnetostrictive material which expands and contracts based on the strength of magnetic fields therein;
magnetic field means connected to a portion of said magnetostrictive material, for providing said magnetic fields within said magnetostrictive material;
an optical waveguide that guides light;
first reflection means, disposed along said waveguide in the path of a source light, for providing a first reflected light having a first reflection wavelength, and for providing a first transmitted light;
second reflection means, disposed along said waveguide in the path of said first transmitted light from said first reflection means, for providing a second reflected light at a second reflection wavelength and for providing a second transmitted light;
light from said first and said second reflection means making up an output light signal;
said first and said second reflection means being mechanically connected to said magnetostrictive material and being oriented non-parallel to each other;
said magnetostrictive material and said magnetic field means being oriented so as to cause the strength of the magnetic field in said magnetostrictive material to increase while a metallic object is nearby, thereby causing a dimension of said magnetostrictive material to increase and causing one of said reflection means to be stretched; and
said first and said second reflection wavelength being substantially equal to each other while said metallic object is not nearby and being unequal while said metallic object is nearby, thereby causing the magnitude of said output light signal to change while said metallic object is nearby.
1 Assignment
0 Petitions
Accused Products
Abstract
An optical speed sensor includes a laser diode 10 that provides a broadband source light 12 to a coupler 18 which provides a source light 22 to a fiber Bragg grating 26 which reflects a first reflection wavelength of light 28 and passes the remainder as a light 30. The light 30 is incident on another fiber Bragg grating 32 which reflects a second reflection wavelength of light 34. The power of an output signal 40 is indicative of the reflected light beams 34,28, and is measured by a photodetector 46. The gratings 26,32 are mounted on a magnetostrictive material 60 which is connected to a permanent magnet 62 which is connected to a material 70 which conducts magnetic fields. The material 60 expands and contracts in response to the strength of magnetic fields therein. The reflection wavelengths for both gratings 26,32 are the same when the tooth 100 is not nearby, thereby causing the output signal 40 to be primarily equal to the reflected light 28. However, when the tooth 100 is nearby, the material 60 and the grating 32 expands causing the reflection wavelengths to separate, thereby causing the power of the output signal 40 to increase. Because both gratings 26,32 are on the same material thermal expansions will have no effect on the sensor measurement. Alternatively, one of the gratings 26,32 may be mounted to the material 70 or the magnet 62. The detection may performed in either reflection or transmission mode.
105 Citations
28 Claims
-
1. An optical sensor, comprising:
-
a magnetostrictive material which expands and contracts based on the strength of magnetic fields therein; magnetic field means connected to a portion of said magnetostrictive material, for providing said magnetic fields within said magnetostrictive material; an optical waveguide that guides light; first reflection means, disposed along said waveguide in the path of a source light, for providing a first reflected light having a first reflection wavelength, and for providing a first transmitted light; second reflection means, disposed along said waveguide in the path of said first transmitted light from said first reflection means, for providing a second reflected light at a second reflection wavelength and for providing a second transmitted light; light from said first and said second reflection means making up an output light signal; said first and said second reflection means being mechanically connected to said magnetostrictive material and being oriented non-parallel to each other; said magnetostrictive material and said magnetic field means being oriented so as to cause the strength of the magnetic field in said magnetostrictive material to increase while a metallic object is nearby, thereby causing a dimension of said magnetostrictive material to increase and causing one of said reflection means to be stretched; and said first and said second reflection wavelength being substantially equal to each other while said metallic object is not nearby and being unequal while said metallic object is nearby, thereby causing the magnitude of said output light signal to change while said metallic object is nearby. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. An optical sensor, comprising:
-
a magnetostrictive material which expands and contracts based on the strength of magnetic fields therein; magnetic field means connected to a portion of said magnetostrictive material, for providing said magnetic fields within said magnetostrictive material; a non-magnetostrictive material connected to a portion of said magnetic field means; an optical waveguide that guides light; first reflection means, disposed along said waveguide in the path of a source light, for providing a first reflected light at a first reflection wavelength, and for providing a first transmitted light; second reflection means, disposed along said waveguide in the path of said first transmitted light from said first reflection means, for providing a second reflected light at a second reflection wavelength and for providing a second transmitted light; light from said first and said second reflection means making up an output light signal; one of said reflection means being mechanically connected to said magnetostrictive material and the other of said reflection means being mechanically connected to said non-magnetostrictive material; said magnetostrictive material and said magnetic field means being oriented so as to cause the strength of the magnetic field in said magnetostrictive material to increase while a metallic object is nearby, thereby causing a dimension of said magnetostrictive material to increase and causing said reflection means mechanically connected thereto to be stretched; and said first and said second reflection wavelength being substantially equal to each other while said metallic object is not nearby and being unequal when said metallic object is nearby, thereby causing the magnitude of said output light signal to change while said metallic object is nearby. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
Specification