JPH11223574A - Method and device for measuring scattered light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for speedily measuring the characteristics of scattered light from luminescent points scattered in an optical fiber with high resolution and high light focusing efficiency. SOLUTION: With a section of an optical fiber 1 supported linearly, the optical fiber 1 is moved by an optical fiber moving device 100. Light is made incident into the optical fiber 1 from its end face by a light incidence means 200 including a light source 201 to transmit light through the optical fiber 1. An ellipsoidal reflecting mirror 320 is installed so that a linearly moving part 2 of the optical fiber 1 may pass through the first focal point 323 of the ellipsoidal reflecting mirror 320. Scattered light leaking from the optical fiber 1 located at the first focal point 323 of the ellipsoidal reflecting mirror 320 is focused at a location different from the travelling route of the optical fiber 1 through the use of the ellipsoidal reflecting mirror 320 and a flat reflecting mirror 310. The distribution of the amount of the light is measured by a light amount distribution measuring means 400.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measurement technique, and more particularly to a method and an apparatus for measuring scattered light from the side of an optical fiber.

[0002]

2. Description of the Related Art In an optical fiber, for example, a plastic optical fiber, when scattered light leaking from a side surface is irradiated with strong light from an end face, bright spots which are bright and bright may be visible to the naked eye in some cases. Such luminescent spots are often caused by foreign matter or air bubbles contained in the core of the optical fiber as a scattering source, and in a case where a flaw generated at an interface between the core and the sheath is a scattering source.
Since the scattered light from such a bright spot generally has directivity, the intensity sharply changes depending on the observation angle. For this reason, especially when observed in the dark, it is brilliant and very conspicuous, which may be a factor in reducing the commercial value depending on the use.
Therefore, in the optical fiber, it is required to reduce harmful bright spots, in order to obtain an optical fiber that meets such requirements, the intensity of scattered light of the bright spots, the number of bright spots,
It is important to analyze the position of the luminescent spot, the direction of the scattered light, and the like to find the cause.

As a measuring method for measuring the scattered light of the optical fiber for such a purpose, a method using an integrating sphere and a method of rotating the optical fiber around a central axis to obtain a total solid angle distribution of the scattered light have conventionally been used. (Japanese Patent Application Laid-Open No. 60-17 / 1985)
No. 3438) is known.

In a first conventional method using an integrating sphere, an optical fiber is passed through an integrating sphere, light is incident from one end face of the optical fiber, and light scattered from the side of the optical fiber in the integrating sphere is collected. The scattered light is taken out from a hole formed in one place of the integrating sphere, and the scattered light is detected by a photodetector to measure the amount of scattered light.

In a second conventional method for measuring the total solid angle distribution of scattered light, a pair of holders arranged at an appropriate distance is used to linearly rotate an optical fiber around its central axis. To grip. And a lens system and a photodetector on a turntable rotatable around one straight line orthogonal to the central axis of the optical fiber, toward an intersection between the rotation axis of the turntable and the central axis of the optical fiber. Fix the condenser tube with a narrow receiving angle. A bath containing a matching oil filled with a refractive index matching oil is arranged around a rotation axis of the turntable, and a linear portion of the optical fiber is immersed in the bath containing the matching oil. Light is incident from one end face of the optical fiber, and scattered light in one direction is measured by using a condenser tube from outside the bus. Here, when the optical fiber is rotated around its central axis, scattered light emitted at a fixed angle with respect to the optical fiber central axis can be measured. The scattered light emitted at another angle with respect to the central axis of the optical fiber can be measured by rotating the condenser tube around the rotation axis of the turntable. Thereby, the scattered light at one point of the optical fiber can be measured over the entire solid angle.

[0006]

A problem with the first conventional method is that no information can be obtained on the directivity of the scattered light of the optical fiber. In addition, since the amount of light is detected by repeating irregular reflection by the integrating sphere, there is no actual reflecting surface of the integrating sphere having a reflectance of 100%. Another disadvantage is that a photodetector is required.

A problem with the second conventional method is that although detailed data can be obtained on the characteristics of the bright spot, it takes a lot of time and effort to measure one point. Also,
The length of the optical fiber between a pair of holders that rotate synchronously cannot be so long, and it is necessary to grasp the optical fiber in order to rotate it synchronously, so that there is a problem that measurement cannot be performed while continuously moving the optical fiber. . For this reason, it is not easy to measure scattered light for a long optical fiber. However, the second conventional method requires a large amount of data for a long optical fiber to sufficiently analyze a defect such as a bright spot of an optical fiber. Not suitable for analysis.

An object of the present invention is to provide a method and an apparatus for quickly measuring the characteristics of scattered light from luminescent spots scattered in an optical fiber with high resolution and high light collection efficiency.

[0009]

According to the present invention, in order to achieve the above object, light is propagated in an optical fiber running while at least a part of the optical fiber is held in a straight line. Measuring the scattered light leaking from the side surface of the optical fiber, using a concave reflector installed so that the linear running portion of the optical fiber passes through the focal point of the concave reflector, the light located at the focal point of the concave reflector A method for measuring scattered light, comprising collecting scattered light leaking from a fiber at a position different from a traveling path of an optical fiber and measuring a light amount distribution thereof.

In one embodiment of the present invention, the measurement is performed in a state where the central axis of the optical fiber in the straight running portion of the optical fiber and the optical axis of the concave reflecting mirror are aligned.

In one embodiment of the present invention, the portion of the optical fiber that is continuous with the linear running portion is run on a running path that is separated from an extension of the straight line. Focus scattered light on the line.

In one embodiment of the present invention, an elliptical reflecting mirror is used as the concave reflecting mirror, and the optical fiber is arranged so that the straight running portion of the optical fiber passes through the first focal point of the elliptical reflecting mirror.

According to the present invention, in order to achieve the above object, light is propagated in an optical fiber running while at least a part thereof is held in a straight line, and leaks from a side surface of the optical fiber. In the method for measuring the scattered light, the elliptical reflector is installed such that the linear running portion of the optical fiber passes through the first focal point of the elliptical reflector, and the first focal point and the second focal point of the elliptical reflector. Using an optical path changing element disposed between the focal point and the optical fiber, the scattered light leaking from the optical fiber located at the first focal point of the ellipsoidal reflecting mirror is condensed at a position different from the optical fiber traveling path, and its light amount distribution And a method for measuring scattered light, characterized by measuring

In one embodiment of the present invention, the measurement is performed in a state where the optical axis of the ellipsoidal reflecting mirror and the central axis of the optical fiber in the straight running portion of the optical fiber coincide.

In one embodiment of the present invention, a flat reflecting mirror or a prism provided with an opening for running an optical fiber is used as an optical path changing element.

In one embodiment of the present invention, an elliptical reflector having an optical fiber traveling opening at its optical axis is used as the concave or elliptical reflector.

According to the present invention, in order to achieve the above object, light is propagated into an optical fiber running while at least a part thereof is held in a straight line, and leaks from a side surface of the optical fiber. In the method for measuring the scattered light, a parabolic reflector is installed using a parabolic reflector installed such that the central axis of the optical fiber in the linear running portion of the optical fiber passes through the focal point of the parabolic reflector. The scattered light leaking from the optical fiber located at the focal point of the reflecting mirror is made into a parallel light group, and the parallel light group is condensed at a position different from the traveling path of the optical fiber using a light condensing element, and the light amount distribution is measured. A method for measuring scattered light, characterized by the following.

In one embodiment of the present invention, the measurement is performed in a state where the optical axis of the parabolic reflector and the central axis of the optical fiber are aligned.

In one embodiment of the present invention, a convex lens is used as a light-collecting element, and a portion connected to the linear running portion of the optical fiber is run on a running path away from an extension of the central axis of the optical fiber. In this state, the parallel light group is condensed on the extension where the optical fiber does not travel.

In one aspect of the present invention, a convex lens is used as a light-collecting element, and further, an optical path changing element is used to transfer the light that is the group of parallel rays to a position away from a straight line including the central axis of the optical fiber. Collect light.

In one embodiment of the present invention, a plane reflecting mirror or a prism provided with an opening for running an optical fiber is used as an optical path changing element.

In one embodiment of the present invention, a parabolic reflector having an opening for running an optical fiber at its optical axis is used as the parabolic reflector.

In one embodiment of the present invention, light is emitted from the side of a running optical fiber to propagate the light into the optical fiber.

According to the present invention, there is provided an optical fiber moving device for moving at least a part of an optical fiber while keeping the optical fiber in a straight line. A light source for incidence, a concave reflecting mirror arranged so that one point on the central axis of the optical fiber that is held in a straight line and travels is focused, and a concave reflecting mirror that is arranged at a position different from the traveling path of the optical fiber. There is provided a scattered light measuring device comprising a light amount distribution measuring device for measuring a light amount distribution of light condensed by a mirror.

In one embodiment of the present invention, an elliptical reflecting mirror is used as the concave reflecting mirror, and the optical fiber is held linearly and runs so that the central axis of the optical fiber passes through the first focal point of the elliptical reflecting mirror. doing.

According to the present invention, an optical fiber moving device for moving at least a part of an optical fiber while holding the optical fiber in a straight line, and a device for transmitting light into the optical fiber. A light source for incidence, an ellipsoidal reflecting mirror arranged so that one point on the center axis of the optical fiber running linearly held and running is the first focus, and the optical axis coincides with the center axis of the optical fiber, An optical path changing element disposed between the first focal point and the second focal point of the ellipsoidal reflecting mirror, and a light quantity distribution of light collected by the light collecting element, which is disposed at a position different from a traveling path of the optical fiber. A scattered light measuring device comprising a light amount distribution measuring device.

In one embodiment of the present invention, a plane reflecting mirror or a prism provided with an opening for running an optical fiber is used as an optical path changing element.

In one embodiment of the present invention, an elliptical reflector having an optical fiber running opening at its optical axis is used as the concave or elliptical reflector.

According to the present invention, in order to achieve the above object, an optical fiber moving device for moving at least a part of an optical fiber in a state of being held in a straight line, and transmitting light into the optical fiber. A light source for incidence, a parabolic reflector arranged so that one point on the center axis of an optical fiber that is held in a straight line and travels, and an optical fiber located at the focal point of the parabolic reflector A condensing element for condensing the scattered light that leaks and is converted into a group of parallel rays by the parabolic reflector at a position different from the traveling path of the optical fiber; and a light condensing element. A scattered light measuring device comprising a light amount distribution measuring device for measuring a light amount distribution is provided.

In one embodiment of the present invention, the parabolic reflector is arranged such that its optical axis coincides with the central axis of the optical fiber.

In one embodiment of the present invention, an optical fiber moving device and a light condensing element are arranged so that a portion connected to the linear running portion of the optical fiber runs on a running path away from an extension of the straight line. And a light-condensing element arranged so that the extension line on which the optical fiber does not travel is a light-condensing position of the parallel light group.

In one embodiment of the present invention, a convex lens is used as a light-collecting element, and an optical path changing element is used to set a position away from a straight line including the central axis of the optical fiber as the parallel light group. A light-collecting element and an optical-path changing element arranged to be at the light-condensing position are used.

In one embodiment of the present invention, a flat reflecting mirror or a prism provided with an opening for running an optical fiber is used as an optical path changing element.

In one embodiment of the present invention, a parabolic reflector having an opening for running an optical fiber at its optical axis is used as the parabolic reflector.

In one embodiment of the present invention, the light quantity distribution measuring device is a light spot position detecting element.

In one embodiment of the present invention, the light quantity distribution measuring device is an image sensor.

In one embodiment of the present invention, the light source is a light source that is disposed on the side of the optical fiber running path and that allows propagation light to enter the optical fiber from the side surface of the optical fiber.

[0038]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9, parts or members having similar functions are denoted by the same reference numerals.

FIG. 1 is a view schematically showing a first embodiment of a method and an apparatus for measuring scattered light of an optical fiber according to the present invention. In the present embodiment, the optical fiber moving device 100 and the light incident means 2 are main components of the device.
00, a concave reflecting mirror typified by an elliptical reflecting mirror 320 and a parabolic reflecting mirror 320 ', an optical path changing element 310, and a light amount distribution measuring means 400 are used. Hereinafter, each means will be described in order.

The optical fiber moving device 100 comprises a bobbin 11 in which the optical fiber 1 is mounted on a constant tension feeding mechanism 110.
1 through a through hole 311 of a plane reflecting mirror 310 as an optical path changing element and an access hole 321 of an elliptical reflecting mirror 320 as a concave reflecting mirror. , And the tip is
Fixed to. Then, the nip roller 130 is rotated in the direction of arrow 131 by its driving mechanism (not shown), so that the two guide pulleys 121 and 1 are rotated.
Between 22, the linear portion of the optical fiber can be moved continuously or intermittently along the central axis thereof while the linear portion 2 of the optical fiber is generated. A curved portion 3 is formed between the straight portion 2 and the tip of the optical fiber 1.

Next, the light incidence means 200 will be described. The output light 202 of the light source lamp 201 is
Then, the light is focused on the optical fiber 1 from the end face 5 of the optical fiber 1 fixed to the holder 210, and the light is propagated into the optical fiber 1. As the light incident on the optical fiber 1, light having a wavelength at which the transmission loss of the optical fiber is small and having a numerical aperture equal to or smaller than the numerical aperture of the optical fiber is preferable.

Next, the elliptical reflecting mirror 320 and the optical path changing element 310 which are typical examples of the concave reflecting mirror will be described. The ellipsoidal reflecting mirror 320 is set so that its optical axis 322 coincides with the central axis 4 of the linear portion 2 of the optical fiber 1, and the plane reflecting mirror 310 is positioned such that its reflecting mirror surface 312 is positioned with respect to the optical fiber central axis 4. It is installed so as to be inclined at an angle of 45 degrees. At this time, the intersection 328 between the mirror surface 312 of the plane reflecting mirror 310 and the optical axis 322 of the elliptical reflecting mirror 320 is the first focal point 323 and the second focal point of the elliptical reflecting mirror 320 (the focal point farther from the elliptical reflecting mirror surface 325). : Not shown). Each of the flat reflecting mirror 310 and the elliptical reflecting mirror 320 is provided with a holder (not shown) having a three-dimensional position adjusting mechanism and a passage for the optical fiber 1 (through hole 31).
1 and an access hole 321), and can be accurately installed at a desired position. In such an arrangement, when a point light source is placed at the first focal point 323, the light emitted from the point light source is a representative light ray 326,
As shown at 327, the reflecting mirror surface 3 of the elliptical reflecting mirror 320
The light is reflected by the mirror 25, the light path is changed by the action of the plane reflecting mirror 310, and the light is condensed at the light condensing point 324. First focus 32
The sum of the distance between 3 and the intersection 328 and the distance between the intersection 328 and the converging point 324 is 2
Equal to the distance between two focal points.

Next, the light amount distribution measuring means 400 will be described. An iris diaphragm 402 is provided on a light-collecting surface 329 that is perpendicular to the reflection optical axis 330 (perpendicular to the optical axis 322 and forms an angle of 45 degrees with the mirror surface 312 of the plane reflecting mirror 310) and that includes the light-collecting point 324.
The scattered light beam that has passed through the iris diaphragm is received by the light spot position detecting element 401, and the light amount and the coordinates of the center of gravity of the light amount distribution on the condensing surface are detected. Although not shown, in order to prevent stray light from entering the light spot position detection element 401,
The parts of the elliptical reflecting mirror 320, the plane reflecting mirror 310 and the light quantity distribution measuring means 400 are surrounded by a dark box provided with an entrance of the optical fiber 1. This dark box may be installed as necessary to prevent the influence of light from the outside, and can be simplified or omitted when the entire apparatus is operated in a dark room.

Next, the operation of the apparatus of the first embodiment as described above will be described with respect to the case of measuring the bright spot of the optical fiber.
explain.

The output light of the light source lamp 201 is made incident on the optical fiber 1 from the end face 5 of the optical fiber 1, and the nip roller 130 is moved at a constant speed in the direction of the arrow 131 while propagating in the optical fiber 1. When the optical fiber 1 is rotated and slowly moved, the state of light distribution on the light collecting surface 329 changes variously, reflecting the light scattering state of the optical fiber 1 near the first focal point 323. For example, in the case of a normal optical fiber having no bright spots, the scattered light is weak and scattered light is generated over the entire optical fiber. In the case of the defective optical fiber 1 having a bright spot, when the bright spot passes through the first focal point 323, the coordinates of the bright spot in the optical fiber cross section and the bright spot image on the condensing surface 329 (the center of gravity of the light amount distribution) )
Has a fixed relationship with the coordinates of the light source, and a sharp image is generated on the light-converging surface, reflecting the bright spot position in the cross section of the optical fiber.
Since the direction of the scattered light changes depending on the position of the bright spot in the cross section of the optical fiber, the direction of the scattered light can be known to some extent by knowing the position of the bright spot in the cross section of the optical fiber. Further, when a luminescent spot not on the central axis of the optical fiber 1 approaches and passes through the first focal point 323, the image crosses the light-collecting surface 329 almost linearly. The direction in which the image appears is determined by the coordinates of the position of the bright spot in the cross section of the optical fiber. The sharpest image on the light-collecting surface 329 is the moment when the bright spot passes through the first focal point 323. . By knowing the moment when the bright spot passes through the first focus, the position of the bright spot in the direction of the central axis of the optical fiber can be known.

Because of this relationship, the light-collecting surface 329
By measuring the light amount distribution in the optical fiber, the coordinates of the bright spot in the optical fiber cross section, the position of the bright spot in the direction of the optical fiber central axis, the brightness, and the direction of the scattered light can be known.

Further explanations and various modifications of the main parts constituting the apparatus of the present embodiment will be described below.

First, the optical fiber moving device 100 will be described. The most important function of the mobile device is the optical fiber 1
Is held linearly at least at the focal position of the concave reflecting mirror. Guides and tension retention are particularly important for this purpose, for which there are various implementation means. As for the guide, the guide pulley is used in the above embodiment, but the present invention is not limited to this. For example, by arranging two pairs of nip rollers so that their holding directions are orthogonal to each other and performing the positioning and the movement of the optical fiber, the running position of the optical fiber can be accurately maintained. Further, a V-shaped or U-shaped guide having a fixed arrangement, a circular guide slightly larger than an optical fiber, a chuck for working, or the like can be used. There are various methods for applying tension. For example, there is a method in which an optical fiber is grasped by two pairs of nip rollers, one of which can be driven at a constant speed or intermittently, and the other is driven by a torque motor or a slip mechanism.

It is important for the light incident means 200 that a sufficient amount of light is incident on the scattered light measurement. If the amount of incident light is not sufficient, the scattered light may be too weak and the measurement may be inaccurate. When measuring a long optical fiber, it is particularly important to select a wavelength at which the transmission loss of the optical fiber is small. By doing so, sufficiently strong light can be scattered from the optical fiber at the measurement position (the focal point of the concave reflecting mirror). When the optical fiber to be measured is very long (for example, when the optical fiber is long endlessly as in the case of manufacturing an optical fiber), the light is irradiated from the side of the optical fiber with a strong light source to enter the optical fiber. Light can be directed to generate a small amount of light that propagates in the optical fiber. In this case, it is preferable to combine with a highly sensitive light quantity distribution measuring means. As the light source, various lamps, semiconductor light emitting devices, and lasers can be used, and these can be used in combination with a spectroscope or an optical filter as needed. The condensing lens 203 can be used in combination with an appropriate stop so as to have an appropriate numerical aperture. However,
An aperture may not be required depending on the type of light source. Also,
The light source is not limited to one that emits continuous emission DC light, and may emit intermittent emission AC light using a chopper or the like. In this case, for example, a process is performed in which the AC light is set to a frequency different from that of noise light such as external light, and a signal obtained by the light amount distribution measuring unit 400 is selected by a signal of light having a frequency used for the AC light. , It is possible to reduce the influence of external light.

Elliptical reflecting mirror 320 and optical path changing element 31
The important thing about 0 is that the optical fiber is
The second objective is to pass through or near the first focal point 323 of the optical fiber 20 and to collect the scattered light of the optical fiber in a place where no optical fiber exists. Then, in order to detect the scattered light of the optical fiber symmetrically with respect to the central axis, it is preferable that the optical axis of the elliptical reflecting mirror coincides with the central axis of the optical fiber near the first focal point. When arranging the optical fiber such that the optical fiber does not exist on the second focal point, the optical path changing element can be omitted.For example, in order to omit the optical path changing element, the center axis and the optical axis are moved to the first focal point. It is also possible to make them cross each other at an angle, and to set the converging point (second focal point) in a place where there is no optical fiber. Although the case where the plane reflecting mirror is used at an angle of 45 degrees is shown as the optical path changing element, the angle is not limited to 45 degrees. Further, as the optical path changing element, a prism can be used as the reflection type, and a wedge-shaped prism can be used as the transmission type. It is also possible to arrange an optical path changing element and an elliptical reflecting mirror in this order from the optical fiber incident end face side.

An important component of the light quantity distribution measuring means 400 is an optical sensor. As the light spot position detecting element 401 used as an optical sensor in the above embodiment, for example, a two-dimensional semiconductor position detecting element S1 manufactured by Hamamatsu Photonics KK
300 can be suitably used. This is a detection element capable of measuring the light quantity distribution, and continuously outputs the position signal of the center of gravity of the light quantity distribution and the light quantity signal. In addition, an image sensor such as a CCD or an image pickup tube can be used. When only the light amount of the bright spot is required, an ordinary light sensor having a single light receiving surface can be used. Further, when it is desired to roughly know the position of the luminescent spot, a two-part or multi-part optical sensor can be used.
Alternatively, a light guide such as an optical fiber is
It is also possible to arrange between 9 and an optical sensor. The iris diaphragm can be omitted when the size of the optical sensor is small.

FIG. 2 is a diagram schematically showing a second embodiment of the present invention. In the present embodiment, in-line scattered light measurement is performed.

In this embodiment, the light incident means 200 irradiates light from the side surface 6 of the optical fiber 1. Further, the optical fiber moving device 100 continuously supplies the optical fiber 1 from the optical fiber supply unit 151, and the guide pulleys 121, 1
22, the optical fiber is held linearly between them to form the optical fiber linear portion 2 and the optical fiber take-up portion 1
Take it at 52.

The light incident means 200 focuses the output light 202 of the light source lamp 201 on the optical fiber by the focusing lens 203. Most of this irradiation light passes through the optical fiber 1 and goes out of the optical fiber from its side surface.
A part is scattered by Rayleigh scattering or the like of the core material and is converted into light propagating in the optical fiber 1.

The light incident means 200 is installed between the optical fiber supply section 151 and the guide pulley 121 in FIG. 2, but may be installed between the optical fiber take-off section 152 and the guide pulley 122. Or you may install in both. In FIG. 2, light is irradiated to the linear portion of the optical fiber. However, light is irradiated to the optical fiber bent by a pulley, light is irradiated to the optical fiber obliquely, and light passes through the optical fiber. It is possible to increase the amount of light propagating in the optical fiber by, for example, irradiating the optical fiber again with the reflected light by a reflecting plate or the like.

Next, the optical fiber moving device 1 of the present embodiment
00 will be described. The optical fiber supply unit 151 is a device for manufacturing an optical fiber or a device for supplying an optical fiber from a bobbin. The optical fiber supply unit 151 can move the optical fiber at a constant tension and speed in conjunction with the optical fiber take-off unit 152. Is a device that can move an endless optical fiber. In FIG. 2, the positions of the optical fiber supply unit 151 and the optical fiber pickup unit 152 may be interchanged.

FIG. 3 is a diagram partially and schematically showing a third embodiment of the present invention.

This embodiment corresponds to the first and second embodiments in which a right-angle prism 350 is used as an optical path changing element instead of a plane reflecting mirror.

The mirror surface 352 of the right-angle prism 350 plays the same role as the mirror surface 312 of the plane reflecting mirror in the first and second embodiments, and the mirror surface 352 of the right-angle prism is the same as the mirror surface 352 described in the first embodiment. Mirror surface 312
It is located at the same position as. The path of light when a point light source is arranged at the first focal point 323 will be described in the same manner as in the first embodiment. The right-angle prism 350 includes a holder (not shown) with a three-dimensional position adjustment mechanism and an optical fiber passage (through hole 351), and can be accurately installed at a desired position.

The prism is preferably a right angle prism,
Other angles can be used as long as the reflection surface satisfies the condition of total reflection. A reflection film may be formed on the reflection surface, and in this case, the condition for total reflection becomes unnecessary.

FIG. 4 is a diagram schematically showing a fourth embodiment of the present invention.

This embodiment is different from the first embodiment in the concave reflecting mirror. That is, in the fourth embodiment, a parabolic reflector 320 'is used as a concave reflector. 322
And 323 'are their optical axis and focus, respectively. The optical axis 322 of the parabolic reflecting mirror coincides with the central axis of the optical fiber linear portion 4. Also, a convex lens 36 as a light-collecting element
0 is used, and the convex lens is provided between the plane reflecting mirror 310 and the light amount distribution measuring means 400. Convex lens 3
The optical axis of 60 coincides with the reflected optical axis 330. In addition, a spherical reflecting mirror, an elliptical reflecting mirror, a parabolic reflecting mirror, or the like can be used as the light collecting element.

When a point light source is placed at the focal point 323 'of the parabolic reflector 320', the light emitted from the point light source is
As shown by its representative rays 326,327,
The light is reflected by the reflecting surface 325 of the parabolic reflecting mirror, is converted into a parallel light flux, is reflected by the plane reflecting mirror 310, and is
The light is condensed to its focal position 324 by 60. This light condensing position (focal position) 324 is located on the light converging surface 329 of the light quantity measuring means 400.

It is also possible to arrange an optical path changing element and a parabolic reflecting mirror in this order from the optical fiber incident end face side.

In this embodiment, the measurement of the scattered light can be performed in the same manner as in the first embodiment.

FIG. 5 is a diagram schematically showing a fifth embodiment of the present invention.

This embodiment corresponds to the second embodiment in which a parabolic reflector is used as a concave reflector and a convex lens is used as a condenser.

In this embodiment, the measurement of the scattered light can be performed in the same manner as in the second embodiment.

FIG. 6 is a diagram partially and schematically showing a sixth embodiment of the present invention.

The present embodiment corresponds to the fourth and fifth embodiments in which a right-angle prism 350 similar to that used in the third embodiment is used as an optical path changing element instead of a plane reflecting mirror. The arrangement of the mirror surface 352 of the right-angle prism 350 and the traveling direction of light are the same as in the third embodiment.

FIG. 7 is a diagram schematically showing a seventh embodiment of the present invention.

This embodiment is different from the fourth embodiment in that
This corresponds to a configuration in which the arrangement of optical fibers is changed without using a plane reflecting mirror. That is, the parabolic reflector 320 'and the convex lens 360 are coaxially arranged, and the position of the light quantity distribution measuring means 400 is changed accordingly. Further, the traveling direction of the optical fiber 1 pulled out from the bobbin 111 of the optical fiber moving device 100 is changed to a right angle direction by a guide pulley 121. The optical fiber 1 forms a linear portion 2 between the guide pulley 121 and the guide pulley 122.

When a point light source is placed at the focal point 323 'of the parabolic reflector 320', the light emitted from the point light source is:
As shown by its representative rays 326,327,
The light is reflected by the reflecting surface 325 of the parabolic reflecting mirror, converted into a parallel light beam, and condensed by the convex lens 360 to the focal position 324 thereof. At this time, since a part of the parallel light beam is blocked by the guide pulley 121 to form a shadow, it is preferable to use the guide pulley 121 having a size and shape that minimizes the shadow.

In this embodiment, the measurement of the scattered light can be performed in the same manner as in the fourth embodiment.

FIG. 8 is a diagram schematically showing an eighth embodiment of the present invention.

In this embodiment, the optical fiber moving device 100
And the configuration of the light incident means 200 are different from those of the seventh embodiment. That is, in the eighth embodiment, the light incident means 200 irradiates light from the side surface 6 of the optical fiber 1 as in the second embodiment. Also, the optical fiber moving device 100
First, the optical fiber 1 is continuously supplied from the optical fiber supply unit 151, the traveling direction is changed to a right angle direction by the guide pulley 121, and the optical fiber is linearly inserted between the guide pulley 121 and the guide pulley 122. The portion 2 is formed, its traveling direction is changed to a right angle direction by the guide pulley 122, and the portion is taken out by the optical fiber take-out section 152.

In the present embodiment, the measurement of the scattered light can be performed in the same manner as in the seventh embodiment.

FIG. 9 is a diagram partially and schematically showing a ninth embodiment of the present invention.

This embodiment corresponds to the seventh and eighth embodiments in which a light-collecting element (convex lens) is not used and an elliptical reflecting mirror 320 is used as a concave reflecting mirror.

In this embodiment, instead of the combination of the parabolic reflector and the convex lens in the seventh and eighth embodiments,
Ellipsoidal reflecting mirror 3 as used in the first and second embodiments
20 is used. The elliptical reflecting mirror 320 is installed such that its optical axis 322 coincides with the central axis 4 of the linear portion 2 of the optical fiber 1.

In such an arrangement, the elliptical reflecting mirror 3
When a point light source is placed at the first focal point 323 of the light source 20, the light emitted from the point light source will have its representative rays 326, 32
7, the reflecting surface 325 of the ellipsoidal reflecting mirror
And is condensed on a converging point 324 on the converging surface 329 of the light amount distribution measuring means.

The case where an elliptical reflecting mirror or a parabolic reflecting mirror is used as the concave reflecting mirror has been described above. However, the concave reflecting mirror is not limited to these, and for example, a spherical reflecting mirror may be used. Implementation of the present invention is possible.

[0083]

According to the present invention, the characteristics (three-dimensional position, direction of scattered light, brightness, etc.) of the luminescent spot, which is a defect scattered in a long optical fiber, are improved with high resolution and high light collection efficiency. It is possible to measure quickly. Next, the effects will be described in more detail.

First, the first effect is that scattered light from the optical fiber can be obtained symmetrically and simultaneously with information on the direction of the scattered light and the position of the luminescent spot. Moreover, since the concave reflecting mirror can collect scattered light in a wide angle range including a direction perpendicular to the optical fiber central axis, it is possible to obtain information that is in good agreement with the result observed with the naked eye.

The second effect is that the light-collecting efficiency is high and a relatively low-cost photodetector can be sufficiently used. This is because the scattered light from the bright point is reflected once by the concave reflecting mirror and possibly the optical path changing element (and possibly transmitted through the light collecting element) and reaches the light quantity measuring means.

The third effect is that the light quantity distribution on the focal plane of the concave reflecting mirror can be measured while moving the long optical fiber, so that the three-dimensional position of the bright spot can be measured with high resolution and quickly. is there.

The fourth effect is that measurement can be performed without cutting the optical fiber in the optical fiber manufacturing process, for example.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing a second embodiment of the present invention.

FIG. 3 is a diagram partially and schematically showing a third embodiment of the present invention.

FIG. 4 is a diagram schematically showing a fourth embodiment of the present invention.

FIG. 5 is a diagram schematically showing a fifth embodiment of the present invention.

FIG. 6 is a diagram partially and schematically showing a sixth embodiment of the present invention.

FIG. 7 is a diagram schematically showing a seventh embodiment of the present invention.

FIG. 8 is a diagram schematically showing an eighth embodiment of the present invention.

FIG. 9 is a diagram partially and schematically showing a ninth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 optical fiber 2 linear portion of optical fiber 3 curved portion of optical fiber 4 central axis of linear portion of optical fiber 5 optical fiber end surface 100 optical fiber moving device 110 constant tension feeding mechanism 111 bobbin 121, 122 guide pulley of optical fiber 130 Nip roller 151 Optical fiber supply section 152 Optical fiber take-off section 200 Light incidence means 201 Light source 203 Condensing lens 310 Planar reflecting mirror (optical path changing element) 311 Through hole 312 Mirror surface 320 Elliptical reflecting mirror (Concave reflecting mirror) 320 'Release Object surface reflecting mirror (concave reflecting mirror) 321 Access hole 322 Optical axis 323 First focus 323 'Focus 324 Focus point 325 Reflecting surface 326,327 Representative light beam 328 Mirror surface of flat reflecting mirror and optical axis of elliptical reflecting mirror Intersection 329 Condensing surface 330 Reflected optical axis 350 Zum 351 through hole 352 mirror 360 lens 400 the light amount distribution measuring means 401 point position detecting element 402 an iris diaphragm

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Maehara 20-1 Miyukicho, Otake City, Hiroshima Pref. Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (29)

[Claims] 1. A method for measuring a scattered light leaking from a side surface of an optical fiber by propagating light into an optical fiber running while at least a part of the optical fiber is held in a straight line. Using a concave reflector installed so that it passes through the focal point of the concave reflector, scattered light leaking from the optical fiber located at the focal point of the concave reflector,
A method for measuring scattered light, comprising condensing light at a position different from the travel path of an optical fiber and measuring the light amount distribution. 2. The method according to claim 1, wherein the measurement is performed in a state where the central axis of the optical fiber in the linear running portion of the optical fiber and the optical axis of the concave reflecting mirror are aligned. 3. A scattered light is collected on an extension of the optical fiber where the optical fiber does not travel while a portion connected to the linear travel portion of the optical fiber is traveled on a travel path away from the extension of the straight line. 3. A method according to claim 1 or claim 2, wherein the method comprises illuminating. 4. An ellipsoidal reflecting mirror is used as the concave reflecting mirror,
A method according to any of the preceding claims, characterized in that the straight running part of the optical fiber is arranged so as to pass through the first focal point of the ellipsoidal reflector. 5. A method for measuring a scattered light leaking from a side surface of an optical fiber by propagating light into an optical fiber running while at least a part thereof is held in a straight line, wherein the linear running portion of the optical fiber is measured. The elliptical reflector is installed so that it passes through the first focal point of the elliptical reflector, and the optical path changing element disposed between the first focal point and the second focal point of the elliptical reflector, the ellipse A method for measuring scattered light, comprising collecting scattered light leaking from an optical fiber located at a first focal point of a surface reflecting mirror at a position different from a traveling path of the optical fiber, and measuring a light amount distribution thereof. 6. The method according to claim 5, wherein the measurement is performed in a state where the optical axis of the ellipsoidal reflecting mirror and the central axis of the optical fiber in the linear running portion of the optical fiber are aligned. 7. The method according to claim 5, wherein a flat reflecting mirror or a prism provided with an opening for running an optical fiber is used as the optical path changing element. 8. As a concave reflecting mirror or an elliptical reflecting mirror,
The method according to any one of claims 1 to 7, wherein an elliptical reflector having an opening for running an optical fiber is provided in an optical axis portion thereof. 9. A method of measuring a scattered light leaking from a side surface of an optical fiber by propagating light into an optical fiber running while at least a part thereof is held linearly, wherein the linear running portion of the optical fiber is measured. Using a parabolic reflector installed so that the central axis of the optical fiber passes through the focal point of the parabolic reflector, scattered light leaking from the optical fiber located at the focal point of the parabolic reflector is converted into parallel rays. A method of measuring scattered light, comprising collecting a group of parallel rays at a position different from a traveling path of an optical fiber by using a light-collecting element as a group, and measuring a light amount distribution thereof. 10. The method according to claim 9, wherein the measurement is performed with the optical axis of the parabolic reflector being aligned with the central axis of the optical fiber. 11. An optical fiber, wherein a convex lens is used as a light-collecting element, and a portion connected to a linear running portion of the optical fiber is run on a running path away from an extension of a central axis of the optical fiber. The method according to claim 9 or 10, wherein the parallel light group is collected on the extension that is not running. 12. A light collecting device comprising: a convex lens as a light condensing element; and an optical path changing element for condensing the light of the parallel light beam group at a position away from a straight line including a central axis of the optical fiber. The method according to claim 9 or claim 10, wherein 13. The method according to claim 12, wherein a flat reflecting mirror or a prism provided with an opening for running an optical fiber is used as the optical path changing element. 14. The parabolic reflector according to claim 9, wherein a parabolic reflector having an opening for running an optical fiber at an optical axis thereof is used as the parabolic reflector. The method described in Crab. 15. The method according to claim 1, wherein light is emitted from a side surface of the traveling optical fiber, and the light is propagated in the optical fiber. 16. An optical fiber moving device for running at least a part of an optical fiber in a linear state, a light source for causing light to enter the optical fiber, and an optical fiber running in a linear state. A concave reflecting mirror disposed so as to focus on one point on the central axis of the optical fiber, and a light amount distribution measuring a light amount distribution of light condensed by the concave reflecting mirror disposed at a position different from a traveling path of the optical fiber. A scattered light measuring device consisting of a device. 17. An elliptical reflecting mirror is used as the concave reflecting mirror, and the optical fiber is held linearly and runs so that the central axis of the optical fiber passes through the first focal point of the elliptical reflecting mirror. 17. The apparatus according to claim 16, wherein: 18. An optical fiber moving device for running at least a part of an optical fiber in a straight line, a light source for causing light to enter the optical fiber, and an optical fiber running in a straight line. A point on the central axis of the elliptical reflector, the first focal point, the elliptical reflector arranged so that the optical axis coincides with the central axis of the optical fiber, between the first focal point and the second focal point of the elliptical reflective mirror A scattered light measuring device comprising a light path changing element disposed and a light amount distribution measuring apparatus disposed at a position different from the optical fiber traveling path and measuring a light amount distribution of light collected by the light collecting element. 19. The apparatus according to claim 18, wherein a flat reflecting mirror or a prism provided with an opening for running an optical fiber is used as the optical path changing element. 20. The method according to claim 1, wherein the concave or elliptical reflector is an elliptical reflector having an optical fiber opening at its optical axis.
An apparatus according to any one of claims 6 to 19. 21. An optical fiber moving device for running at least a part of an optical fiber in a linear state, a light source for injecting light into the optical fiber, and an optical fiber running in a linear state A parabolic reflector arranged so that one point on the central axis of the mirror is a focal point; scattered light leaking from an optical fiber located at the focal point of the parabolic reflector; Scattered light measuring device, comprising: a light collecting element for collecting light taken at a position different from the traveling path of the optical fiber, and a light amount distribution measuring device for measuring the light amount distribution of the light collected by the light collecting element. . 22. The apparatus according to claim 21, wherein the parabolic reflector is arranged such that its optical axis coincides with the central axis of the optical fiber. 23. An optical fiber moving device configured to cause a portion connected to a straight running portion of the optical fiber to run on a running path apart from an extension of the straight line, a convex lens as a light collecting element, and an optical fiber 23. The apparatus according to claim 21, wherein a light condensing element arranged so that a light converging position of the light of the group of parallel rays is used on the extension line on which the light beam does not travel is used. 24. Using a convex lens as a light condensing element and further using an optical path changing element, a position apart from a straight line including a central axis of the optical fiber is set as a light condensing position of the parallel light rays. 23. The apparatus according to claim 21, wherein a light condensing element and an optical path changing element disposed in the apparatus are used. 25. The apparatus according to claim 24, wherein the optical path changing element is a plane reflecting mirror or a prism provided with an opening for running an optical fiber. 26. A parabolic reflector, wherein a parabolic reflector having an opening for running an optical fiber is provided in an optical axis portion thereof, as the parabolic reflector.
An apparatus according to any one of the above. 27. The apparatus according to claim 16, wherein the light quantity distribution measuring device is a light spot position detecting element. 28. The apparatus according to claim 16, wherein the light quantity distribution measuring device is an image sensor. 29. The light source according to claim 16, wherein the light source is a light source arranged on a side of the optical fiber running path, and capable of entering propagation light into the optical fiber from a side surface of the optical fiber. An apparatus according to any one of the above.