Abstract:
Provided is a technique for mass-producing a conductor to which is fixed a current detection head that detects the value of current flowing in the conductor, and in which the relationship between the detection value and the current value is stabilized. The head comprises a lens, a magneto-optical element, a conductor, and a fixing member, and the lens, the magneto-optical element, and the conductor are respectively fixed to the fixing member. An optical system is formed using the current detection head such that light is guided through the lens to the magneto-optical element, and light affected by a magneto-optical effect due to the magneto-optical element is guided to the lens. All of the members contributing to current detection are fixed to the fixing member, and therefore the relative positional relationships of all the members contributing to current detection are uniquely determined, enabling conductors with little variation in current detection characteristics to be mass-produced. A shape for determining the positional relationship between the fixing member and the conductor may be formed therebetween in advance, and the positioned current detection head and conductor may be fixed to obtain the conductor.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a National Stage of International Application No. PCT/JP2011/068160 filed Aug. 9, 2011, the contents of all of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a conductor to which is fixed a current detection head which detects the value of current flowing in the conductor. Further, the present invention relates to a current detection head used in the manufacture of a conductor to which a current detection head is fixed. 
     DESCRIPTION OF RELATED ART 
     In order to detect the value of current flowing in a conductor, techniques using magneto-optical effects have been developed. Japanese Patent Application Laid-open No. S60-202365 discloses a current detection device wherein a magneto-optical element is fixed to an outer face of a conductor, an incidence optical fiber connects the magneto-optical element and a light source, and an emission optical fiber connects the magneto-optical element and a light-receiving device. In the technique of Japanese Patent Application Laid-open No. 860-202365, the intensity of light guided to the light-receiving device is measured. When current flows in the conductor, a magnetic field acts on the magneto-optical element, and when a magnetic field acts on the magneto-optical element, the Faraday effect acts on light passing through the magneto-optical element, causing rotation of the plane of polarization; when the plane of polarization rotates, the intensity of light received by the light-receiving device changes. The value of current flowing in the conductor determines the magnetic field intensity, the magnetic field intensity determines the rotation angle, and the rotation angle determines the intensity of light received by the light-receiving device, so that in the current detection device of Japanese Patent Application Laid-open No. S60-202365, the value of current flowing in the conductor is detected from the intensity of light measured by the light-receiving device. 
     Japanese Patent Application Laid-open No. H9-145809 discloses a current detection head provided with an incidence optical fiber, rod lens, total-reflection mirror, polarizer, magneto-optical element, detector, total-reflection mirror, and emission optical fiber. In the technique of Japanese Patent Application Laid-open No. H9-145809, a gap is provided in a core which makes a circuit about a conductor, and the above-described current detection head is installed in this gap. In the technique of Japanese Patent Application Laid-open No. H9-145809, by miniaturizing the current detection head the gap interval is narrowed, the magnetic field intensity occurring in the core is increased, and the current detection sensitivity is raised. 
     When detecting the value of current flowing in a conductor using the Faraday effect, the Kerr effect, or another magneto-optical phenomenon, the position of the magneto-optical element relative to the conductor, the direction of the magneto-optical element relative to the conductor (for example the direction of the magnetization easy axis of the magneto-optical element relative to the conductor), the positions of the incidence fiber and incidence lens relative to the magneto-optical element, and the positions of the emission fiber and emission lens relative to the magneto-optical element, and similar, greatly affect the relation between detection value and current value. When mass-producing conductors to which current detection heads are fixed, if the aforementioned positional relationships and similar are not stable, there is substantial variation in the detection characteristics (the relation between detection value and current value) among conductors. Conductors with stable detection characteristics cannot be mass-produced. 
     Japanese Patent Application Laid-open No. S60-202365 explains only that a magneto-optical element is fixed to a conductor and that one end of an incidence optical fiber and one end of an emission fiber are fixed to the magneto-optical element; the importance of the positional relationships explained in the preceding paragraph is not recognized. In Japanese Patent Application Laid-open No. S60-202365, there is no recognition of the problem in which, if for example the positional relationship between the incidence optical fiber and the emission optical fiber shifts, the relation between the intensity of light measured by the light-receiving device and the value of current flowing in the conductor shifts greatly, and no measures to address this are taken. 
     In Japanese Patent Application Laid-open No. H9-145809, with respect to the optical system from the incidence optical fiber to the emission optical fiber, positional relationships between members are adjusted to desired positional relationships. However, in Japanese Patent Application Laid-open No. H9-145809 the position and direction of the current detection head relative to the conductor are not determined. Japanese Patent Application Laid-open No. H9-145809 does not recognize the problem that, if the position and direction of the magneto-optical element relative to the conductor are not determined, the relation between the intensity of light measured by the light-receiving device and the value of current flowing in the conductor shifts greatly, and no measures to address this are taken. 
     BRIEF SUMMARY OF INVENTION 
     This invention provides a technique wherein, when mass producing conductors incorporating current detection heads, mass production of a group of conductors for which there is little variation in the relation between detection value and current value is possible. 
     The present application relates to a conductor with a current detection head fixed. The current detection head is provided with a lens, a magneto-optical element, and a fixing member; and the lens, the magneto-optical element, and the conductor are respectively fixed to the fixing member. In this state, an optical system is formed such that light is guided through the lens to the magneto-optical element, and light affected by a magneto-optical effect due to the magneto-optical element is guided to the lens. 
     Here the lens may be demarcated into a lens for incidence and a lens for emission, or the lens may be used for both incidence and emission. The magneto-optical element may be a material in which an optical phenomenon occurs which changes depending on the magnetic field intensity, and may be a material which exhibits the Faraday effect, or may be a material which exhibits the magnetic Kerr effect. The fixing member may comprise an integrated member, or may comprise two or more members which, when combined to form a shape for mutual positioning, ensures a constant mutual positional relationship. 
     In a conductor of the present application, the lens, magneto-optical element, and conductor are each fixed to the fixing member, and therefore the position of the magneto-optical element relative to the conductor, the direction of the magneto-optical element relative to the conductor (for example, the direction of the easy axis of magnetization relative to the conductor), the position of the incidence lens relative to the magneto-optical element, the position of the emission lens relative to the magneto-optical element, and all other positional relationships significantly affecting detection results, are adjusted to and fixed in constant positional relationships. Conductors with small variation in the relation between detection values and current values can be mass-produced. 
     If a fixing portion to fix the fixing member to the conductor is formed on the fixing member, and a positioning shape for maintaining a positional relationship between the fixing member and the conductor at a prescribed position is formed therebetween, then by fixing the fixing member on the conductor, conductors can be mass-produced in which the current detection head is fixed in the prescribed position. 
     One end of an optical fiber may be fixed to the fixing member, with the optical fiber extending from the current detection head. In this case, the task of connecting the current detection head and a light-emitting device, or of connecting the current detection head and a light-receiving device, is simplified. A light guiding path can be secured by the space between a lens and a mirror. A light guiding path formed of a lens and a mirror may be used instead of the optical fiber. An optical fiber is not indispensable. 
     In a case where the conductor is a conducting plate, it is preferable that the fixing member is fixed to one face of the conducting plate. In this case, it is preferable that an optical system be formed such that the magneto-optical element exhibits the magnetic Kerr effect, and light which has passed through the lens is reflected by the magneto-optical element, and the light affected by the magnetic Kerr effect is returned to the lens. In this case also, a lens for incidence and a lens for emission may be provided separately, or a lens may be used for both incidence and emission. 
     If an optical system in which reflection occurs at the magneto-optical element is used, by fixing the fixing member to one face of the conducting plate, the positional relationship of the optical system to the conducting plate is adjusted to an intended positional relationship, and a fixed state can be obtained. A conductor group with a stable relationship between detection value and current value can be mass-produced simply. 
     In a case where a current detection head, to which an optical fiber is extended, is fixed to the conductor, it is preferable that the end portion of the optical fiber be fixed to a base plate. The base plate is disposed in a position facing one face of the conducting plate to which the fixing member is fixed. If a penetrating hole is formed in the base plate, the end portion of an optical fiber can be inserted into the penetrating hole and fixed. Further, a light source and a light-receiving device can be disposed on the base plate. Hence the positional relationship of the optical fiber and light source is adjusted, and the positional relationship of the optical fiber and light-receiving device is adjusted by, the base plate. The base plate can be used to dispose the light source to cause polarized light to be incident on the end portion of the optical fiber for incidence and the light-receiving device which outputs an electrical signal corresponding to the rotation angle of polarized light emitted from the end portion of the optical fiber for emission. The light-receiving device may be a device which outputs an electrical signal corresponding to the rotation angle occurring due to the magnetic Kerr effect, or may be a device which detects the intensity of the polarized light after the polarized light is affected by the magnetic Kerr effect and passes through a polarizing filter, or may be a device which detects the intensity ratio or intensity difference of polarization components in two orthogonal directions. 
     The fixing member may be configured from an integrated member, or the fixing member may be configured by combining a first fixing member and a second fixing member. In this case, positioning shapes to ensure a constant mutual positional relationship when the two are combined are formed on both the first fixing member and the second fixing member. 
     In a case where a first fixing member and second fixing member are combined to configure a fixing member, the optical fiber and lens may be fixed to the first fixing member and the magneto-optical element and conductor may be fixed to the second fixing member, or the optical fiber may be fixed to the first fixing member and the lens, magneto-optical element, and conductor may be fixed to the second fixing member. 
     Using the above-described configuration, manufacture of a first fixing member to which are fixed the “optical fiber and lens” or the “optical fiber”, and of a second fixing member to which are fixed the “lens, magneto-optical element and conductor” or the “magneto-optical element and conductor”, is facilitated, and manufacture of the fixing member is facilitated. 
     If a shape for adjusting a positional relationship between the conductor and the second fixing member at a prescribed position is formed in advance on the second fixing member, by fixing the second fixing member to the conductor, conductors in which the current detection head is fixed at a prescribed position can be mass-produced. 
     By using an optical fiber, a light guiding path can be secured simply. In this case, an optical fiber for incidence and an optical fiber for emission may be prepared separately, or an optical fiber may be used for both directions. Further, a single optical fiber provided with a first core through which light toward the magneto-optical element passes, and a second core through which light from the magneto-optical element passes may be used. In the latter case, only a single optical fiber is needed. 
     Similarly, a lens through which light toward the magneto-optical element passes and a lens through which light from the magneto-optical element passes may be prepared separately, or a lens may be used for both directions. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded view of a conductor to which is fixed a current detection head in Example 1. 
         FIG. 2  is an enlarged view of the current detection head of  FIG. 1 . 
         FIG. 3  illustrates the configuration of the light source and light-receiving device connected to the current detection head of  FIG. 1 . 
         FIG. 4  explains the positional relationship and directional relationship between a conductor, magneto-optical element and light path. 
         FIG. 5  is an exploded view of a conductor to which is fixed a current detection head in Example 2. 
         FIG. 6  illustrates the relation between detection value and current value when the current detection head is fixed in Example 2. 
         FIG. 7  illustrates the relation between detection value and current value when the current detection head is fixed in the prior art. 
         FIG. 8  is an exploded view of a conductor to which is fixed a current detection head in Example 3. 
         FIG. 9  illustrates a current detection head in Example 4. 
         FIG. 10  illustrates a current detection head in Example 5. 
         FIG. 11  illustrates a current detection head in Example 6. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
       FIG. 1  illustrates the current detection head  70  of a first example. The reference symbol  22  denotes a fixing member, integrally molded using a resin; a magneto-optical element  28 , lens  24 , the lower end of an incidence optical fiber  14  which guides light to the lens  24 , and the lower end of an emission optical fiber  16  which guides light from the lens  24 , are fixed to the fixing member  22 . Further, mounting holes  30  and  32  are formed at prescribed positions in the fixing member  22 , and mounting holes  36  and  38  are also formed at prescribed positions in the conducting plate  34 . If a bolt  18  is passed through the mounting holes  30  and  36  and tightened with a nut  40 , and a bolt  20  is passed through the mounting holes  32  and  38  and lightened with a nut  42 , the fixing member  22  is fixed to the conducting plate  34 . Using the mounting hole  30  of the fixing member  22 , the mounting hole  36  of the conducting plate  34 , and the bolt  18 , the position of the mounting hole  30  relative to the conducting plate  34  is fixed, and using the mounting hole  32  of the fixing member  22 , the mounting hole  38  of the conducting plate  34  and the bolt  20 , the position of the mounting hole  32  relative to the conducting plate  34  is fixed. Because two places of the fixing member  22  are positioned relative to the conducting plate  34 , the position and direction of the fixing member  22  are positioned constantly relative to the conducting plate  34 . Through use of the mounting holes  30  and  32  in the fixing member  22  and the mounting holes  36  and  38  in the conducting plate  34 , the relative positional relationship between the fixing member  22  and the conducting plate  34  is positioned in a constant position. The mounting holes  30  and  32  formed in the fixing member  22  and the flange portion in which the mounting holes  30  and  32  are formed serve as a fixing portion which fixes the fixing member  22  to the conducting plate  34 . 
     Because the lower end of the incidence optical fiber  14 , the lens  24 , the magneto-optical element  28 , the lower end of the emission optical fiber  16 , and the conducting plate  34  are all positioned and fixed by the fixing member  22 , the relative positional relations between all of the lower end of the incidence optical fiber  14 , the lens  24 , the magneto-optical element  28 , the lower end of the emission optical fiber  16 , and the conducting plate  34  are always adjusted to be constant and fixed. 
     The base plate  6  is disposed in a position facing the conducting plate  34 . Penetrating holes  8  and  10  are formed in the base plate  6 ; the upper end of the incidence optical fiber  14  is inserted into the penetrating hole  8  and fixed, and the upper end of the emission optical fiber  16  is inserted into the penetrating hole  10  and fixed. The reference symbol  12  denotes the fixing member which fixes the upper end of the incidence optical fiber  14  and the upper end of the emission optical fiber  16 , and is positioned on the base plate  6 . The light source  2 , which makes polarized light incident on the upper end of the incidence optical fiber  14 , is fixed at the upper portion of the penetrating hole  8 . The light-receiving device  4 , which receives polarized light emitted from the upper end of the emission optical fiber  16 , is fixed at the upper portion of the penetrating hole  10 . The light source  2  and light-receiving device  4  are fixed by the base plate  6 . 
     Details of the light source  2  are illustrated in  FIG. 3 . The light source  2  comprises a semiconductor laser  52 , a polarizing prism  54  and a lens  56 ; laser light polarized by the polarizing prism  54  is input to the incidence optical fiber  14 . The light-receiving device  4  comprises a lens  58 , beam splitter  60 , first photodiode  62 , second photodiode  64 , and op-amp  66 . The beam splitter  60  is provided with a function to divide light into two depending on the polarization direction, and the polarization plane of light incident on the first photodiode  62  and the polarization plane of light incident on the second photodiode  64  are orthogonal. The value of the difference in the intensity of light with the first plane of polarization and the intensity of light with the second plane of polarization, amplified by the op-amp  66 , changes corresponding to the rotation angle of the plane of polarization. 
     In the structure of  FIG. 1 , the conducting plate  34  with the current detection head  70  fixed is mass-produced. Optical fibers  14  and  16  extend from the current detection head  70 . The upper ends of these optical fibers  14  and  16  are fixed to the base plate  6 . The optical fiber  14  connects the light source  2  and magneto-optical element  28 , and the optical fiber  16  connects the magneto-optical element  28  and the light-receiving device  4 , to complete the current detection device. 
     Action of the current detection device of  FIG. 1  is explained. The semiconductor laser  52  emits laser light. This laser light passes through the polarizing prism  54 , and consequently only a light component polarized in a specific plane of polarization passes through the lens  56  and is incident on the optical fiber  14 . As illustrated in  FIG. 2 , the optical path of the polarized light reaching the lower end of the optical fiber  14  is changed to an oblique direction by the lens  24 , and the polarized light reaches the upper face of the magneto-optical element  28 . Having reached the upper face of the magneto-optical element  28 , the polarized light is reflected by the upper face of the magneto-optical element  28 . 
     The conducting plate of  FIG. 1  is long in the direction perpendicular to the plane of the paper, and current I flows in a direction perpendicular to the plane of the paper.  FIG. 1  corresponds to a cross-sectional view along line A-A in  FIG. 4 . Hence the magnetic field H in the left-right direction in  FIG. 1  and  FIG. 2  acts on the magneto-optical element  28 . When polarized light is reflected by the upper face of the magneto-optical element  28  on which the magnetic field H is acting, a magnetic Kerr effect (in this case, the longitudinal Kerr effect) occurs. A crystal which exhibits the magnetic Kerr effect is selected for the magneto-optical element  28 . Because the magnetic Kerr effect occurs, the plane of polarization of the polarized light reflected by the upper face of the magneto-optical element  28  rotates. That is, the plane of polarization of the incident light  46  is not the same as the plane of polarization of the reflected light  48 , and rotation occurs. Reference  44  in  FIG. 2  indicates the incident light within the lens  24 , and reference  50  in  FIG. 2  indicates the reflected light within the lens  24 . 
     Light reflected by the upper face of the magneto-optical element  28  passes through the lens  24 , emission optical fiber  16 , lens  58 , and beam splitter  60 , and is incident on the first photodiode  62  and second photodiode  64 . The amplitude value of the difference in the intensity of light with a first polarization plane detected by the first photodiode  62  and the intensity of light with a second polarization plane (orthogonal to the first polarization plane) detected by the second photodiode  64  changes depending on the rotation angle of the polarization plane occurring due to the magnetic Kerr effect. From the output of the op-amp  66 , the angle of rotation of the polarization plane occurring due to the magnetic Kerr effect, the intensity of the magnetic field H acting on the magneto-optical element  28  which caused the rotation angle, and the magnitude of the current I which caused the magnetic field intensity, are detected. 
     When mass-producing the conducting plate  34  with a current detection head  70  of  FIG. 1  to  FIG. 3 , in order to mass-produce the conducting plate  34  with a stabilized relation between detection value and current value, it is important that the relative positional relationships and the relative directional relationships between members contributing to current detection be adjusted and fixed in constant relations. 
     As illustrated in  FIG. 4 , the intensity of the magnetic field H occurring when a current I is flowing in the conducting plate  34  changes with the position relative to the conducting plate  34 . Hence the relative positional relationship between the conducting plate  34  and the magneto-optical element  28  is important. The magneto-optical element  28  is provided with an easy magnetization axis J. The angle of rotation of the polarization plane occurring due to the magnetic Kerr effect is also affected by the angle θ 1  made by the easy magnetization axis J and the magnetic field H. Hence the angle θ 1  made by the easy magnetization axis J of the magneto-optical element  28  and the conducting plate  34  is also important. The angle of rotation of the polarization plane occurring due to the magnetic Kerr effect is also affected by the angles made by the easy magnetization axis J and the incident light  46  (the horizontal-direction angle θ 2  and the perpendicular-direction angle θ 3 ). The relative positional relationships between the optical fiber  14 , the lens  24 , the magneto-optical element  28 , and the optical fiber  16  are important. 
     In the current detection device of  FIG. 1  to  FIG. 3 , the optical fiber  14 , lens  24 , magneto-optical element  28 , optical fiber  16 , and conducting plate  34  are respectively fixed to the fixing member  22 , so that the relative positional relationships and relative directional relationships of the optical fiber  14 , lens  24 , magneto-optical element  28 , optical fiber  16 , and conducting plate  34  are adjusted in constant relationships and fixed. In this example, all of the members  14 ,  24 ,  28 ,  16  and  34  contributing to current detection are fixed to the fixing member  22 , so that the relative positional relationships and relative directional relationships (angular relationships) of all of the members  14 ,  24 ,  28 ,  16  and  34  contributing to current detection are adjusted in constant relationships and fixed. By using the current detection device of  FIG. 1  to  FIG. 3 , conducting plates  34  with current detection heads  70  with a stabilized relation between detection value and current value can be mass-produced. 
     Further, using the base plate  6  the relative positional relationships and relative angular relationships between the upper end of the optical fiber  14 , the semiconductor laser  52 , the polarizing prism  54 , and the lens  56  are adjusted in constant relationships and fixed. Moreover, using the base plate  6 , the relative positional relationships and relative angular relationships of the upper end of the optical fiber  16 , lens  58 , beam splitter  60 , first photodiode  62 , and second photodiode  64  are adjusted in constant relationships and fixed. These elements also contribute to mass production of conducting plates  34  with current detection devices in which the relation between detection value and current value is stabilized. 
     The fixing member  22  may be formed as a single physical object, as illustrated in  FIG. 1 , or may be formed using two physical objects, as illustrated in  FIG. 5 . In the case of  FIG. 5 , an example is illustrated in which the optical fibers  14  and  16  are fixed to a first fixing member  22   a , and the lens  24  and magneto-optical element  28  are fixed to a second fixing member  22   f . A pair of concavities  22   b  and  22   e  is formed in the first fixing member  22   a , and a pair of engaging claws  22   d  and  22   e  is formed on the second fixing member  22   f  When the first fixing member  22   a  and the second fixing member  22   f  are combined, in a state in which the engaging claw  22   d  meshes with the concavity  22   b  and the engaging claw  22   e  meshes with the concavity  22   c , the first fixing member  22   a  and second fixing member  22   f  are fixed. In this state, the relative positional relationship of the first fixing member  22   a  and second fixing member  22   f  is adjusted in a constant relationship and fixed. Upon combining the first fixing member  22   b  and second fixing member  22   f , the relative positional relationship of the first fixing member  22   a  and second fixing member  22   f  is stabilized, and the relative positional relationships and relative angular relationships of the lower end of the optical fiber  14 , lens  24 , magneto-optical element  28 , and lower end of the optical fiber  16  are adjusted in constant relationships and fixed. 
     On the second fixing member  22   f  are formed a flange  22   g  for positioning and fixing to the conducting plate  34 , and mounting holes  30  and  32 . The flange  22   g  and mounting holes  30  and  32  formed on the second fixing member  22   f  serve as a fixing portion to fix the second fixing member  22   f  to the conducting plate  34 . 
     If a bolt  18  is passed through the mounting hole  30  and the mounting hole  36  and is tightened with a nut  40 , and a bolt  20  is passed through the mounting hole  32  and the mounting hole  38  and is tightened with a nut  42 , then the relative positional relationships and relative angular relationships of the lower end of the optical fiber  14 , the lens  24 , the magneto-optical element  28 , the lower end of the optical fiber  16 , and the conducting plate  34  are adjusted in constant relationships and fixed. 
     In this example, a concavity  34   a  is formed in the conducting plate  34 , and the magneto-optical element  28  is accommodated within the range of the thickness of the conducting plate  34 . The intensity of the magnetic field acting on the magneto-optical element  28  is increased, and the current detection sensitivity is increased. As illustrated in the examples of  FIG. 1  and  FIG. 5 , the shape of the lens  24  is selected according to the characteristics. 
       FIG. 6  indicates the range of variation in the relation between detection values (the values of the op-amp  66 ) and true current values when the conducting plate  34  to which the current detection head  72  of  FIG. 5  is fixed is mass-produced. The range of variation is small.  FIG. 7  indicates the range of variation in the relation between detection values and current values when conducting plates with current detection heads are mass-produced using a method in which a magneto-optical element is fixed to a conducting plate, a lens is positioned relative to the magnetic-optical element, and an optical fiber is positioned relative to the lens. The range of variation is large. When conducting plates with current detection heads are mass-produced using techniques of the prior art, the relation between detection values and current values varies widely among mass-produced items. 
       FIG. 8  illustrates a third example. Optical fibers  14  and  16  and a lens  24  are fixed to a first fixing member  22   j , and a magneto-optical element  28  is fixed to a second fixing member  22   o . The lens  24  may be fixed to the first fixing member  22   j  as illustrated in  FIG. 8 , or may be fixed to a second fixing member  22   f  as illustrated in  FIG. 5 . 
       FIG. 9  illustrates an example in which a conducting plate  34 , magneto-optical element  28 , lens  24 , and lower end of an optical fiber  15  are insert-molded using a resin material and manufactured. The relative positional relationships of all of the conducting plate  34 , magneto-optical element  28 , lens  24 , and lower end of the optical fiber  15  are fixed in a state of adjustment to be constant by a fixing member  22   r . The conducting plate  34  can be mass-produced with a stabilized relationship between detection values and current values. An opening  34   b  is formed in the conducting plate  34 , and there is no separation of the fixing member  22   r  from the conducting plate  34 . 
     In the case of  FIG. 9 , a core (first core)  14   a  which guides light toward the magneto-optical element  28 , and a core (second core)  16   a  which guides light reflected by the magneto-optical element  28 , are accommodated within a single optical fiber  15 . Because only a single optical fiber  15  is used, connection tasks and similar are simplified. 
       FIG. 10  illustrates an example in which a fixing member  22   s , magneto-optical element  28 , lens  24 , lower end of an optical fiber  14 , and lower end of an optical fiber  16  are insert-molded using a resin material on one face of the conducting plate  34  and manufactured. If grooves  34   c  and  34   d  extending diagonally are formed in the conducting plate  34 , there is no separation of the fixing member  22   s  from the conducting plate  34 . 
       FIG. 11  illustrates an example in which a fixing member  22   t , manufactured by insert-molding a magneto-optical element  28 , lens  24 , lower end of an optical fiber  14 , and lower end of an optical fiber  16  are insert-molded, is fixed to a conducting plate  34  and manufactured. In this example, the diameter of a hole  34   e  formed in advance in the conducting plate  34  and the diameter of a cylindrical portion provided in advance in the lower face of the fixing member  22   t  are managed in a relationship such that the two fit closely. By inserting the cylindrical portion of the fixing member  22   t  into the hole  34   e  of the conducting plate  34 , the position of the fixing member  22   t  relative to the conducting plate  34  can be accurately positioned. Further, screws  18   a  and  20   a  are used to accurately adjust to a constant angle the mounting angle of the fixing member  22   t  relative to the conducting plate  34 . 
     In the above, specific examples of the invention have been explained in detail; but the above are merely exemplifications, and do not limit the scope of claims. The technique disclosed in the scope of claims includes various modifications and alterations of the above-presented specific examples. The technical elements explained in the specification or drawings exhibit technical utility whether independently or in various combinations, and are not limited to combinations disclosed in the claims at the time of filing. Further, techniques exemplified in the specification or the drawings can attain a plurality of objects simultaneously, and technical utility is attained by the attainment itself of one among these objects.