JPS62254070A - Optical fiber-applied voltage sensor - Google Patents

Abstract

PURPOSE:To prevent an increase in the loss of an optical output caused by dust in air and a dew formation phenomenon, by inserting a magneto optical element between electrooptic elements arranged in series and polarization plane maintaining type optical fibers. CONSTITUTION:A plurality of electrooptic elements 17A-17C each having a function of modulating the phase of transmitting light according to a voltage applied are arranged in series continuously through polarization plane maintaining type optical fibers 18A-18C Light transmitted through the final stage of electrooptic element 17C is reflected by a reflector 22 to be transmitted through the electrooptic elements 17A-17C and the optical fibers 18A-18C again. Magnetooptical elements 19A-19E each having a function of turning the polarization plane of the transmission light by 45 deg. in a saturated magnetic field are inserted between the electrooptic elements 17A-17C and the optical fibers 18A-18C connected thereto. Voltages to be measured are applied independently to the electrooptic elements 17A-17C to perform a computation optically for addition and subtraction of the individual voltages being measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical fiber applied voltage sensor that optically performs addition/subtraction calculations on a plurality of voltages to be measured using electro-optic effects.

Conventional technology Conventionally, in order to perform addition/subtraction calculations on multiple voltages to be measured, optical fiber applied voltage sensors were installed at multiple locations, the signals from each sensor were input to an operator, and the calculation was performed electrically. -) was. Therefore, when performing calculations at multiple locations,
A large number of sensors are required, and a computing unit is also required (1). There is.

That is, the light emitted from the light emitting part 1 is
, the lens 3, and the polarizer 4, it becomes parallel light in a straight line (1ij), and becomes circularly polarized light on the side wave plate. 6
A, eB, passing through 6C, V'l, 'V', 7
.

It receives phase modulation corresponding to the voltage of v3 and becomes +1', m circularly polarized light. This elliptically polarized light is separated into two right-angled components by the detector, and each is sent to the light receiving element 1 by condenser lenses 8 and 9.
2.13 and sent to the detection circuit 14 1. This is to perform addition/subtraction calculations on the measured voltages "j", "V2", and "v".

Problems 1 to 1 to be solved by the invention However, in such a configuration, as shown in FIG.
Since the electro-optical elements 6, eB, and ec are not optically connected through the air, the end faces are contaminated by air dust and dew condensation, which causes an increase in optical output loss. An accompanying decrease in sensitivity occurs.

Furthermore, if the distance between eB and eC in the electro-optical element 6 is increased, this will also cause an increase in optical output loss and a decrease in sensitivity. There is a limit to the application to 1i.

Means for Solving the Problems In order to solve the above problems, the present invention provides a plurality of 1t-
The 111-wave blood storage device is serially arranged in series 1 through 9 fibers, and the light that has passed through the final stage electrical element is reflected by a reflector, and the above-mentioned light is reflected again. A plurality of electro-optical elements and polarization planes (transmitting an 1111 people are using a magneto-optical element which has the function of rotating the plane of polarization of the transparent hayt by 46 rotations.

According to the present invention, by the above means, it is possible to completely cut off the portions of the end faces of the plurality of electro-optical elements from the air, thereby eliminating dust and dew condensation caused by the air. Yo-
) can be prevented, and by changing the length of the polarization-maintaining optical fiber, it can be applied even when there are multiple voltage measurement points relatively close together. ” Becomes J-Noh.

Embodiment FIG. 1 shows a case where there are voltages to be measured from three locations as seven points according to an embodiment of the present invention.

In general, polarization-maintaining optical fibers have differences in the thermal characteristics of the propagation constant in each direction of their mutually orthogonal eigenaxes, or in the phase change in response to external pressure due to fiber fluctuations, such as in elliptically polarized light. In the case of light having polarization components on both orthogonal eigenaxes, the phase changes due to changes in ambient temperature, making it difficult to accurately obtain voltage information. In order to solve this problem, a magneto-optical element and a reflector are used to eliminate the change in the phase difference of the inherent polarization with respect to the temperature of the polarization-maintaining optical fiber. That is, the light emitted from the light emitting section 16 made of a semiconductor laser or the like becomes linearly polarized light by a polarization beam, and is focused onto the polarization-maintaining optical fiber 18A by the lens 16. At this time, the linearly polarized direction of the light is made incident at an angle of 46° with respect to the mutually orthogonal polarization characteristic axes of the polarization-preserving optical fiber 18 . The elliptically polarized light that has passed through the polarization-maintaining optical fiber 18A becomes parallel light at the lens 16B and is rotated by the magnet 20. . Next, the electro-optical element 17A converts the light into elliptically polarized light, which undergoes phase modulation proportional to the /ζ voltage v1 applied to the kneader.The magneto-optical element 19B under a saturation magnetic field rotates the polarization direction by 46 degrees, and the lens 16C rotates the polarization direction by 46 degrees. The light is focused on the polarization-maintaining optical fiber 18B, propagates through the polarization-maintaining optical fiber 18B while maintaining information on the phase change due to the voltage v1, and reaches the next stage where the voltage V2 is constant. At the voltage v22 constant part and the voltage Vs 1lllll constant part, the light performs the same operation as in the voltage v11 constant part described above, and the light emitted from the electro-optical element 17C q, ↑ changes the voltage vl * v2 * vS. It has information on the calculated phase change.

Next, this light passes through the phase compensation plate 21 which provides an optical bias, and then is reflected by the reflector 22, and travels along the same path in the opposite direction while repeating the same operation.

Here, in each of the electro-optic elements 1 (X, 17B, and 17A), the elliptical polarization axes in the outward and return passes are in the same direction, and the voltages V, , , V2 in the return pass are the same as in the outbound pass.
．． It becomes elliptically polarized light that has undergone a phase change proportional to V, again.

Further, polarization preserving type optical fibers 18C and 18B.

In each of 18A, the elliptical polarization axes on the outbound and return passes are perpendicular to each other, and the phase changes due to disturbances such as temperature changes that occur on the outbound pass are received in opposite directions on the return pass, resulting in polarization preservation. type optical fibers 18c, 18B,
A phase change of 19 in each of 18 A can be eliminated. That is, 17 electro-optical elements, 17B, 17C, have voltages v1°V2. The polarization maintaining optical fiber 1 is used in the return path to add or subtract the phase change by V.
Polarizing beam splitter 23, lens 1
6c, the light is received by the light receiving element 24.1. Effects of the Invention As described above, according to the present invention, the portions of the end surfaces of the plurality of electro-optical elements through which light passes are completely shielded from air. By changing the length of the polarization-preserving optical fiber, multiple voltage measurement points can be relatively isolated. According to the present invention, the phase modulation according to the voltage will be applied twice in each case, and the sensitivity will be doubled. It is.

[Brief explanation of drawings]

(Fig. 1 is a block diagram of a fiber applied voltage sensor according to an embodiment of the present invention, and Fig. 2 is a block diagram of a conventional optical fiber applied voltage center.) 14...Detection circuit, 15...Light source part,
16... L/lens, 1... Electro-optical element, 18... Polarization preserving optical fiber, 19.
...magnetic crystal, 20...magnet, 21.
... Phase compensation plate, 22 ... Reflector, 23
...Polarized light beam, 24...
Light receiving element. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (2)

[Claims] (1) A plurality of electro-optical elements having a function of modulating the phase of transmitted light according to an applied voltage are successively arranged in series via a polarization-maintaining optical fiber, and the plurality of electro-optical elements An optical fiber applied voltage sensor configured to independently apply a voltage to be measured to each of the voltages to be measured and to optically perform addition/subtraction calculations on each of the voltages to be measured. (2) The light that has passed through the final electro-optical element of the plurality of electro-optical elements is reflected by a reflector, and is transmitted through the plurality of electro-optical elements and the polarization-preserving optical fiber again, so that each of the electric Claim 1: A magneto-optical element having a function of rotating the polarization plane of transmitted light by 45 degrees in a saturated magnetic field is inserted between an optical element and the polarization-maintaining optical fiber connected thereto. Optical fiber applied voltage sensor as described in section.