Fiber optic position and shape sensing device and method relating thereto
The present invention is directed toward a fiber optic position and shape sensing device and the method of use. The device comprises an optical fiber means. The optical fiber means comprises either at least two single core optical fibers or a multicore optical fiber having at least two fiber cores. In either case, the fiber cores are spaced apart such that mode coupling between the fiber cores is minimized. An array of fiber Bragg gratings are disposed within each fiber core. A broadband reference reflector is positioned in an operable relationship to each fiber Bragg grating wherein an optical path length is established for each reflector/grating relationship. A frequency domain reflectometer is positioned in an operable relationship to the optical fiber means. In use, the device is affixed to an object. Strain on the optical fiber is measured and the strain measurements correlated to local bend measurements. Local bend measurements are integrated to determine position or shape of the object.
1 . A fiber optic position and shape sensing device comprising:
an optical fiber means for measuring position and shape, the optical fiber means comprising at least two fiber cores spaced apart wherein mode coupling between the fiber cores is minimized;
an array of fiber Bragg gratings disposed within each fiber core;
a broadband reference reflector positioned in an operable relationship to each fiber Bragg grating wherein an optical path length is established for each reflector/grating relationship; and
a frequency domain reflectometer positioned in an operable relationship to the optical fiber means.
2 . A fiber optic position and shape sensing device according to claim 1 , wherein the optical fiber means is at least two single core optical fibers.
3 . A fiber optic position and shape sensing device according to claim 2 , wherein the optical fiber means is three single core optical fibers, wherein the three fiber cores are non-coplanar and form a triangular shape.
4 . A fiber optic position and shape sensing device according to claim 3 , wherein the three fiber cores each have a center, wherein each center is 120° with respect to each of the other two core centers.
5 . A fiber optic position and shape sensing device according to claim 2 , wherein the array of fiber Bragg gratings are collocated along each single core optical fiber.
6 . A fiber optic position and shape sensing device according to claim 1 , wherein the optical fiber means is a multicore optical fiber.
7 . A fiber optic position and shape sensing device according to claim 6 , wherein the multicore optical fiber comprises three fiber cores.
8 . A fiber optic position and shape sensing device according to claim 7 , wherein the three fiber cores are non-coplanar and form a triangular shape.
9 . A fiber optic position and shape sensing device according to claim 8 , wherein the three fiber cores each have a center, wherein each center is 120° with respect to each of the other two core centers.
10 . A fiber optic position and shape sensing device according to claim 6 , wherein the array of fiber Bragg gratings are collocated along the multicore optical fiber.
11 . A fiber optic position and shape sensing device according to claim 1 , further comprising a wavelength division multiplexing device positioned in an operable relationship to the optical fiber means and the frequency domain reflectometer.
12 . A fiber optic position and shape sensing device according to claim 1 , wherein the frequency domain reflectometer receives signals from the fiber Bragg gratings.
13 . A fiber optic position and shape sensing device according to claim 12 , further comprising a computer positioned in an operable relationship to the frequency domain reflectometer wherein the computer correlates the signals to a strain measurement, converts the strain measurements into local bend measurements, and integrates the local bend measurements into a position or a shape.
14 . A fiber optic method for determining the position and shape of an object, the method comprising the steps of:
a) providing an object;
b) providing a fiber optic position and shape sensing device comprising:
an optical fiber means for measuring position and shape, the optical fiber means comprising at least two fiber cores spaced apart wherein mode coupling between the fiber cores is minimized;
an array of fiber Bragg gratings disposed within each fiber core;
a broadband reference reflector positioned in an operable relationship to each fiber Bragg grating wherein an optical path length is established for each reflector/grating relationship; and
a frequency domain reflectometer positioned in an operable relationship to the optical fiber means;
c) affixing the fiber optic position and shape sensing device to the object;
d) measuring strain on the optical fiber;
e) correlating the strain measurements to local bend measurements;
f) integrating the local bend measurements to determine position or shape of the object.
15 . A fiber optic method according to claim 14 , wherein the object is a position tracking device.
16 . A fiber optic method according to claim 15 , wherein the position tracking device is a robot.
17 . A fiber optic method according to claim 14 , wherein the optical fiber means comprises three cores and wherein the object has a three dimensional shape.
18 . A fiber optic method according to claim 14 , wherein the object is a flexible object.
19 . A fiber optic method according to claim 18 , wherein the flexible object is a medical instrument or a flexible structure.