JP2601123B2 - Optical element holder and optical magnetic field sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical magnetic field sensor for measuring the intensity of a magnetic field by utilizing the Faraday effect of a magneto-optical element, and more particularly to a holder for fixing the magneto-optical element.

[0002]

2. Description of the Related Art Recently, the Faraday effect of a magneto-optical element,
That is, an optical magnetic field sensor that measures the magnetic field strength by using the rotation of the plane of polarization when linear (plane) polarized light passes through a substance in the direction of a magnetic field is small, has excellent insulation properties, and is not affected by electromagnetic noise. Due to such features, it is about to be used as a current sensor that measures the magnitude of current flowing in substations, transmission lines, and distribution lines, which are power transport routes from power plants to consumers, and detects abnormalities.

FIG. 6 shows a basic configuration of an optical magnetic field sensor that has been developed so far. In the drawing, light emitted from a light source such as a laser diode or a light emitting diode propagates through an optical fiber 1 and emerges from an exit end 1a thereof, passes through a lens 2 and a polarizer 3, and becomes linearly polarized light. 4 is incident. And this magneto-optical element 4
The magnetic field to be measured when passing through (hereinafter simply referred to as magnetic field)
In response to the optical rotation, the light passes through the polarizer 5 to have an intensity corresponding to the intensity of the magnetic field, and is further focused by the lens 6 on the incident end 7a of the optical fiber 7.
The light incident on the optical fiber 7 is thereafter guided to a photodetector via the optical fiber 7 and photoelectrically converted.

Here, a polarizing beam splitter is usually used for the polarizer 3 and the polarizer 5, and the two polarizers are set at an angle of 45 degrees. Further, as shown by the arrow A, the measurement magnetic field is parallel to the path of light.

[0005]

The basic structure of the optical magnetic field sensor is as shown in FIG. 6, but when actually manufacturing the sensor, the structure as shown in FIG. 7 is employed. That is, the optical fiber 1 and the optical fiber 7, the lens 2 and the lens 6, the polarizer 3 and the polarizer 5, each including a polarizing beam splitter, the magneto-optical element 4, the total reflection prism 8 for bending the traveling direction of light to a right angle, and the total reflection prism 8. It comprises a reflecting prism 9. Further, the polarizers 3 and 5 of the two polarizing beam splitters need to be arranged on the same plane to facilitate manufacture, and therefore, a half-wave plate 10 is required as an auxiliary component. Here, a portion composed of the total reflection prisms 8 and 9, the polarizers 3 and 5, the magneto-optical element 4, and the half-wave plate 10 constitutes a magnetic field detection unit of the optical magnetic field sensor.

However, when assembling the magnetic field detecting section of such an optical magnetic field sensor, the number of optical elements is large, and it is necessary to fix each optical element while aligning the optical axes. However, there is still no mass-productivity that has been obtained.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an optical element holder for easily fixing an optical element and obtaining an optical center tap (CT) excellent in mass productivity.

[0008]

In order to solve the above-mentioned object, an optical element holder according to the present invention comprises first and second parallel optical element holders.
And a holder body having a holder surface in each plane of the second plane, having a through hole perpendicular to the plane, having a bottom surface parallel to the plane, and forming an opening in the first plane. A first groove having a bottom surface parallel to the plane and having an opening in the second plane; and a bottom surface having a bottom surface parallel to the plane and having a bottom surface parallel to the plane. And a third groove having an opening in a third plane, wherein the through-hole has an opening in a bottom surface of each of the second and third grooves, and a direction in which the first groove extends. The direction in which the second groove extends differs by 45 degrees, the direction in which the first groove extends and the direction in which the third groove extends differs by 90 degrees, and a polarizer is provided in the first and second grooves and the third groove is provided. When the optical element is fitted in the groove, the polarizer and the through hole in the second groove, the optical element in the third groove, the first
The optical axis (path of light) passes through the portion where the third groove opens on the bottom surface of the groove and the polarizer in the first groove.

Further, in the optical magnetic field sensor according to the present invention, a total reflection prism is juxtaposed to the optical element holder in which a polarizer and an optical element are assembled, and a lens and an optical fiber are combined with this. A polarizer and an optical element are assembled to the optical element holder, a total reflection prism is assembled, and a lens and an optical fiber are combined.

[0010]

When forming an optical element holder assembly using the holder of the present invention, the magneto-optical element is fixed to the third groove so as to close the through hole. Next, the polarizer is fixed to the second groove so as to close the through hole. Next, the polarizer is fixed to the first groove so as to cover the through hole. As a result, the same thing as the prior art in which the polarizer, the magneto-optical element, and the half-wave plate are arranged with the optical axis aligned can be obtained without using the half-wave plate.

Further, since the polarizer can be lowered from the holder surface by adjusting the size of the holder and the depth of the groove, the total reflection prism can be arranged in close contact with the holder surface. As a result, the same total reflection prism, polarizer, magneto-optical element, and half-wave plate as those in the conventional method were obtained with the optical axis aligned, and all the optical elements were complicated. This makes it possible to manufacture the magnetic field detecting section of the optical magnetic field sensor without requiring a precise optical position adjustment.

When manufacturing the magnetic field detecting portion of the optical magnetic field sensor using the optical element holder according to the present invention, all the optical position adjustments depend on the mechanical processing accuracy of the holder.
Actually, even with the current machining accuracy, characteristics equivalent to those of the conventional optical magnetic field sensor can be obtained.

Referring to the drawing, when the optical element holder according to the present invention is used, the polarizer 3, the optical element 4,
The polarizer 5 is attached to the optical element holder to form an integrated assembly. When the total reflection prism 8 is disposed on one of two parallel surfaces of the optical element holder assembly and the total reflection prism 9 is disposed in close contact with the other surface, the total reflection prism 8 can be obtained even with the current holder machining accuracy. And 9, the polarizers 3 and 5, and the magneto-optical element 4 can be arranged with their optical axes aligned.

In order to measure the magnetic field strength, the light emitted from a light source such as a laser diode or a light emitting diode propagates through an optical fiber, exits from the exit end, and then passes through a lens to hold the optical element holder of the present invention. The light enters the assembly, passes through the total reflection prism and the polarizer, becomes linearly polarized light, and enters the magneto-optical element. Then, when passing through this magneto-optical element, it receives an optical rotation action according to the strength of the magnetic field,
After passing through the polarizer, the intensity becomes the intensity corresponding to the intensity of the magnetic field. After exiting the total reflection prism, the light is condensed by the lens at the incident end of the optical fiber. The light incident on the optical fiber is thereafter guided to the photodetector via the optical fiber and photoelectrically converted to obtain a measured value.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical element holder body 1 according to an embodiment of the present invention.
6 (hereinafter, referred to as a holder) will be schematically described with reference to FIGS. 1, 2, 3, and 4. FIG.

FIG. 1 is a perspective view of an optical element holder assembly according to an embodiment of the present invention, FIG. 2 is a plan view, FIG. 3 is a side view, and FIG. 4 is a bottom view.

The holder 16 is positioned with respect to a parallel surface (shown by phantom lines in FIG. 3) including the holder surfaces 18 and 19, respectively.
Typically, it is formed of a material such as a synthetic resin or SUS.

The holder 16 has a through hole 11 which is perpendicular to the holder surfaces 18 and 19 and whose center axis is a line passing through the center of the holder 16, and a shallow surface having a bottom surface parallel to the holder surface on the side of the holder surface 18. Groove (first groove) 12, deep groove (third groove)
13 are provided. The shallow groove 12 and the deep groove 13 are grooves orthogonal to each other, and their longitudinal center lines pass through the center lines of the through holes 11.

A groove (second groove) 14 having a bottom surface parallel to the holder surface is provided on the holder surface 19 side. Groove 14
Extends in a direction of 45 degrees with respect to the grooves 12 and 13 that are perpendicular to each other, and the longitudinal center line of the groove passes through the center line of the through hole 11.

An optical magnetic field sensor was assembled using the holder 16 according to the embodiment of the present invention configured as described above.

First, a magneto-optical element having a side surface corresponding to the groove 13 shown in FIGS. 1 and 2 and having a size to close at least the through hole 11 was fixed to the groove 13. Here, (YbTbBi) ₃ Fe ₅ O ₁₂ was used for the magneto-optical element. Next, a polarizer having a side surface that matches the groove 12 and having a size to close at least the through hole 11 is fixed to the groove 12, and a polarizer having a side surface that fits the groove 14 and having a size that closes at least the hole 11. Was fixed in the groove 14. Here, a polar core manufactured by Corning Incorporated was used as the polarizer. Note that a thermosetting adhesive was used to fix each optical element to the holder. In this manner, the polarizer, the through-hole, the magneto-optical element, and the optical element holder assembly 15 through which light can pass through the polarizer were formed.

Next, an optical magnetic field sensor was assembled using the optical element holder assembly 15 to which the optical element was fixed.
The specific configuration is shown in FIG. That is, using a multimode fiber for the optical fiber 1 and the optical fiber 7,
A lens was used for the lens 2 and the lens 6, and a total reflection prism 8 and a total reflection prism 9 for bending the traveling direction of light at a right angle were arranged. Further, the optical element holder assembly 15 according to the embodiment of the present invention, to which the above-described optical element is fixed, is disposed between the total reflection prisms 8 and 9. The total reflection prisms 8 and 9 are actually fixed to the holder surface 18 in FIG. 2 and the holder surface 19 in FIG.

However, when manufacturing the magnetic field detecting section of the optical magnetic field sensor using the optical element holder according to the present invention,
Since all the optical position adjustments rely on the mechanical processing accuracy of the holder, it is a problem whether or not characteristics equivalent to those of the conventional optical magnetic field sensor can be actually obtained. Therefore, in the following examples, a magneto-optical sensor manufactured using the optical element holder according to the present invention and a magneto-optical sensor manufactured by a conventional method will be compared.

Twenty optical magnetic field sensors having the above-described configuration were manufactured, and five of them were selected indiscriminately and their characteristics were measured. The measured characteristics are the sensitivity and the temperature characteristic of the sensitivity (−20 ° C. to + 80 ° C.) in which the deviation of the position adjustment of the optical element appears remarkably.
In the sensitivity). 0.85μm wavelength for light source
Using a light-emitting diode that generates
A photodiode was used. The applied magnetic field is 40 at 60 Hz.
The AC magnetic field was 0e.

For comparison, twenty conventional optical magnetic field sensors shown in FIG. 7 were also manufactured, and five of them were selected indiscriminately.
The sensitivity and the temperature characteristics of the sensitivity were measured. The light source, the photodetector and the applied magnetic field were the same as in the embodiment of the present invention.

Tables 1 and 2 show the results of measuring the sensitivity and the temperature characteristics of the sensitivity of the two types of optical magnetic field sensors, respectively. The column A shows the measurement results of the optical magnetic field sensor manufactured using the optical element holder assembly according to the present invention, and the column B shows the measurement results of the conventional optical magnetic field sensor manufactured for the comparative example.
Column.

[0027]

[Table 1]

[0028]

[Table 2]

From the results of Tables 1 and 2, it can be seen that the characteristics of the optical magnetic field sensor manufactured using the optical element holder assembly according to the embodiment of the present invention and the conventional optical magnetic field sensor hardly vary. That is, it was confirmed that optical position adjustment was performed only by fixing the optical element to the optical element holder body according to the present invention. Therefore, it was confirmed that there was no problem in the mechanical processing accuracy of the holder main body.

[0030]

The following effects can be obtained by using the above-described optical element holder assembly according to the present invention. (1) The optical element sensor can be manufactured without complicated optical position adjustment of the optical element, which is suitable for improving the mass productivity of the optical magnetic field sensor. (2) It is not necessary to use a half-wave plate conventionally required as an auxiliary component. (3) The optical element holder according to the present invention can obtain the same characteristics as the conventional optical magnetic field sensor even with the accuracy obtained by the conventional mechanical processing.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an optical element holder main body according to an embodiment of the present invention.

FIG. 2 is a plan view of an optical element holder main body according to the embodiment of the present invention.

FIG. 3 is a side view of the optical element holder main body according to the embodiment of the present invention.

FIG. 4 is a bottom view of the optical element holder main body according to the embodiment of the present invention.

FIG. 5 is a configuration diagram of an optical magnetic field sensor assembled using the optical element holder assembly according to the embodiment of the present invention.

FIG. 6 is a basic configuration diagram of a conventional optical magnetic field sensor.

FIG. 7 is a specific configuration diagram of a conventional optical magnetic field sensor.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 optical fiber 1a light emitting end of optical fiber 2 lens 3 polarizer 4 magneto-optical element 5 polarizer 6 lens 7 optical fiber 7a light incident end of optical fiber 8 total reflection prism 9 total reflection prism 10 half-wave plate 11 through hole 12 First groove 13 Third groove 14 Second groove 15 Optical element holder assembly to which two polarizers and a magneto-optical element are fixed 16 Optical element holder main body 18 Holder surface 19 Holder surface

Claims (3)

(57) [Claims] 1. A holder body having a holder surface in each of a first and a second plane parallel to each other, a holder body having a through hole perpendicular to the plane, and having a bottom surface parallel to the plane. And a first groove having an opening in the first plane, a second groove having a bottom parallel to the plane and having an opening in the second plane, and a bottom parallel to the plane. A third groove having an opening in a third plane including a bottom surface of the first groove, wherein the through hole has an opening in a bottom surface of the second and third grooves, respectively. The direction in which the first groove extends and the direction in which the second groove extends differ by 45 degrees, the direction in which the first groove extends and the direction in which the third groove extends differs by 90 degrees,
When the polarizer is fitted in the first and second grooves and the optical element is fitted in the third groove, the polarizer in the second groove, the through hole, the optical element in the third groove, An optical element holder, characterized in that an optical axis (path of light) passes through a portion where a third groove opens on the bottom surface of the first groove and a polarizer in the first groove. 2. The optical element holder according to claim 1, wherein a total reflection prism is mounted on the holder surface. 3. An optical magnetic field sensor using the optical element holder according to claim 1.