JPH0723924B2 - Optical fiber coil - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical fiber coil for a sensor in which a portion used as a sensing loop is wound in a coil shape.

2. Description of the Related Art Conventionally, as a sensor used for various purposes, a sensor using an optical fiber has come to be used, which has advantages such as high sensitivity, small size and light weight, and good environmental resistance. It's starting. For example, in a fiber optic gyroscope for detecting the rotational angular velocity of a moving body,
In order to improve the sensitivity, the optical fiber is wound in a coil shape to increase the area surrounded by the fiber.
However, it is known that in a state where the optical fiber is wound in a coil shape and further in a multi-layered state, the temperatures of the respective parts of the optical fiber are different from each other, and as a result, the measurement accuracy is lowered. ing. Then, in order to reduce the influence of such a temperature difference, various methods of symmetrically winding the optical fiber with respect to the sensing coil, various methods of symmetrically winding with respect to the sensing coil, Proposed. FIG. 3 and FIG. 4 show a conventional optical fiber coil. In the figure, 1 is an optical fiber, 2 is a central part of the optical fiber, 3 is a coil bobbin, and 4 is a central axis direction of the sensing coil. As shown in FIGS. 3 and 4, the optical fiber 1 is wound in a coil shape from the middle portion 2 of the entire length thereof, and the optical fibers are alternately coiled with reference to the winding start for each one layer or every two layers. Specifically, optical fibers having a desired length are wound around two rewound bobbins so that they have the same length, and then these bobbins are used as a supply side and for each layer. An optical fiber coil wound symmetrically is manufactured by exchanging the coils on the supply side.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned wound optical fiber coil, since the coil manufacturing process becomes very complicated, the time required for coil manufacturing increases and the manufacturing yield does not improve. There was a problem. In addition, since the optical fiber is wound by jumping over only one layer or two layers, the optical fiber is twisted, distortion occurs, the optical propagation characteristics deteriorate, and the optical fiber itself is easily damaged. At the same time, it also had the problem.

The present invention is to solve such a conventional problem and provides an optical fiber coil having a simple configuration, an extremely small output drift, and a very stable temperature characteristic, and an optical fiber excellent in mass productivity. The coil is also provided at the same time.

Means for Solving the Problems In the optical fiber coil of the present invention, the optical fibers forming the optical fiber coil are substantially the same in the radial direction of the optical fiber coil, with the portions equidistant from the center in the longitudinal direction. The coil is wound so as to come to the position, and has symmetry with respect to the central portion of the coil even in the central axis direction. In addition, a material having excellent thermal conductivity is adopted as the material of the bobbin around which the optical fiber is wound.

Operation The optical fiber coil according to the present invention can reduce the temperature difference between the optical fibers wound around each layer of the coil with respect to the ambient temperature change by the configuration as described above, and It is possible to make the phase error in the interference output signal extremely small. Therefore, variations in light propagation characteristics can be extremely reduced, and detection sensitivity can be improved. Further, as a method of manufacturing this optical fiber coil, since it has symmetry with respect to the central axis direction of the optical fiber coil, it does not change the rotating direction of the fiber coil after winding the fiber on one side. Since the optical fiber coil for the sensing loop can be manufactured only by inverting the fiber coil, the cost of the fiber coil can be reduced at the same time.

Embodiment Hereinafter, one embodiment of the present invention will be briefly described with reference to the drawings. FIG. 1 is a diagram showing a method for manufacturing an optical fiber coil, and FIG. 2 is a sectional view of the optical fiber coil. First, the manufactured optical fiber 1 (FIG. 1a) having a desired length is wound from both ends thereof to the rewinding bobbins 11 and 12 at the same length and divided into two. (FIG. 1b) Further, the fiber coil bobbin 3 is provided with a central portion 2 of the optical fiber.
With reference to, the portions that are equidistant from the central portion 2 are arranged so as to be at substantially the same position in the radial direction of the coil, and are further wound so as to be symmetrical with respect to the central axis. (FIG. 1c) That is, the optical fiber coil 3 and the rewinding bobbin 12 are arranged on the same plane and rotated, and at the same time, tension is applied to the optical fiber 1 from the rewinding bobbin 11.
Is wound around the optical fiber coil 3. Bobbin for rewinding
After winding 11 is completed, the same operation is repeated to wind the optical fiber of the bobbin 12 for rewinding around the optical fiber coil 3. In this method of manufacturing the optical fiber coil, the fibers can be symmetrically wound around the optical fiber coil 3 simply by exchanging the rewinding bobbins 11 and 12.
The manufacturing process of the fiber coil is very simple and can be manufactured in a short time. The vicinity of the central portion 2 of the optical fiber and the detailed winding method of each layer are as shown in FIG. In the present embodiment, the material of the bobbin of the optical fiber coil is Kovar material, stainless steel material or the like, but any other material having good thermal conductivity may be used. Further, although the polarization-maintaining fiber is used as the optical fiber 1, it goes without saying that the coil serving as the sensing loop may be configured using a normal single-mode fiber. The present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

As described above, according to the present invention, the optical fiber is symmetrically wound around the optical fiber coil in the radial direction and the central axis direction of the optical fiber coil. Since it is made of a material having high thermal conductivity, it is possible to provide an optical fiber coil for sensing that can obtain a stable output even when the ambient temperature changes, and it is extremely effective in practice.

[Brief description of drawings]

FIG. 1 is a procedure diagram showing a method of symmetrically winding an optical fiber coil in an embodiment of the present invention, FIG. 2 is a sectional view of an optical fiber coil manufactured by the same method, FIGS. 3 is a cross-sectional view of symmetrical winding of the optical fiber of FIG. 1 ... Optical fiber, 2 ... Fiber middle part, 3 ... Fiber coil, 4 ... Coil center axis, 11, 12 ... Rewind bobbin.

Claims (2)

[Claims] 1. The entire length of the optical fiber is divided into two sections, section (a) and section (b), and the central portions of the sections (a) and (b) are installed in the innermost layer of the multilayer coil. , The optical fibers in the section (a) and the section (b) from the center of the coil with respect to the central axis direction of the coil, respectively.
An optical fiber coil, wherein the first layer is wound in the outer direction and the second layer is wound in the inner direction in turn. 2. The optical fiber coil according to claim 1, wherein a material having a high thermal conductivity is used as a material of the bobbin around which the optical fiber is wound.