JP2003294976A - Method for preventing burnout of resin optical fiber and optical transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing the burnout of the end faces of polymeric optical fibers even when highly photothermal light is made incident on the end faces of the optical fibers. <P>SOLUTION: A coolant booth 5 is disposed between the fiber side end of optical systems (lenses 2 and 4) including a light source 1 and the end faces of the fibers 6a. A translucent liquid is filled in this booth. The end faces of the fibers 6a are cooled and the fiber end faces are shot off from air by the translucent liquid. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-based optical fiber burnout prevention method and an optical transmission device, which can expand the range of application of inexpensive resin-based optical fibers.

[0002]

2. Description of the Related Art Recently, as an optical fiber illumination system,
BACKGROUND ART One in which light obtained from one light source is transmitted by one or a plurality of optical fibers to illuminate a place away from the light source is used in a wide field. According to this system, for example, general-purpose illumination of about 20 lights can be performed using one light source.

According to such an optical fiber illumination system, since ultraviolet rays and infrared rays in the illumination light can be reduced, it is possible to prevent deterioration of the object to be illuminated. Because the optical fiber transmits almost only visible light, almost no heat is generated even when irradiated with light emitted from the tip of the optical fiber (such light is also called cold light). Therefore, it is possible to prevent light and heat from damaging precious works of art and paintings, and also to reduce power consumption by reducing the calorie of the air conditioning system. Further, since the light source and the light emitting unit are separated, there is an advantage that it is suitable for illumination around water and that maintenance such as lamp replacement is easy. Specifically, it is expected to be used in museums, art galleries, museums, multipurpose public spaces, stores, ordinary houses, displays, and others.

If an expensive silica-based optical fiber is used as the optical fiber, the entire system becomes very expensive. Therefore, a polymer-based optical fiber (POF) which is low in production cost and easy to process is used. It is desired to do. However, polymer-based optical fibers have a drawback in heat resistance, and when light with high photoheat is incident from the light source to the light-incident end surface of the optical fiber, the time of the light near the fiber end surface such as the incident light focal point in the optical fiber is reduced. There has been a problem that burnout occurs over time.

By the way, Japanese Patent Application Publication (JP-B) Sho 58-2 discloses a relay circuit housed in a pressure resistant container of an optical submarine repeater and a high voltage resistant pipe of an optical submarine cable. In the feedthrough (introduction part) of the optical submarine repeater for optically coupling with the optical fiber, the optical fiber is arranged in alignment with the optical axis of the condenser lens, and It is described that a space between the end face and the end face is filled with a liquid or jelly-like substance having a refractive index substantially equal to that of the optical fiber. The reason for filling with the liquid or jelly-like substance is to prevent seawater from entering between the condenser lens and the end face of the optical fiber, and not for heat dissipation.

In Japanese Patent Application Laid-Open Publication No. 61-206244, two holes are formed in the side wall of a package when optical coupling of a plurality of optical elements is performed.
It is described that after assembling in air, the gas in the package is replaced with a gas for protecting the end face to close and seal the two holes. The reason for filling with gas in this way is to prevent the semiconductor laser, the light receiver, the lens, and the optical fiber from being oxidized and from adhering dirt, and not for heat dissipation.

On the other hand, Japanese Patent Application Publication (JP-A) No. 61-235806 discloses an apparatus for conveying high-energy electromagnetic radiation from a laser source to an optical fiber, which has an input end and an outlet end. It is described to include a sleeve containing a liquid that is permeable to radiation, the refractive index of said liquid being approximately matched to the refractive indices of the lens and the optical fiber. In the device of FIG. 2 of the same publication, the liquid flows through the device in order to remove the contaminants which may have been generated by the scattered radiation impinging on the walls of the sleeve.

[0008]

However, in the feedthrough of the optical submarine repeater described in Japanese Patent Publication No. S58-2, the heat dissipation effect is improved by disposing the light emitting element in the vicinity of the pressure vessel. Although the structure is described to be easy to adopt, cooling the optical fiber using a liquid filled between the lens and the end face of the optical fiber is not considered. Also, JP-A-61-206244
The optical element package described in No. 1 is a package in which gas is sealed in the package, and liquid is not used in the first place. On the other hand, in the transport device described in Japanese Patent Laid-Open No. 61-235806, a liquid flows through the device to remove contaminants, but it is considered that the liquid is used to cool the optical fiber. Absent.

Therefore, it can be said that the problem that when a polymer optical fiber is used as the optical fiber, the end face of the optical fiber is burnt out with the passage of time has not been solved. It is also conceivable to apply a heat insulating filter to the light source, but in this case, a transmission loss of 30 to 40% will occur.

Therefore, in view of the above points, according to the present invention, even when a light having a high light heat is incident on the light incident end surface of the optical fiber from the light source by using the polymer optical fiber as the optical fiber, It is an object of the present invention to provide a method and an optical transmission device capable of preventing the burnout of a metal.

[0011]

In order to solve the above problems, a method for preventing burnout of a resin-based optical fiber according to the present invention comprises:
It is intended to prevent the end face of the resin-based optical fiber from being burnt out by the light incident from the optical system including the light source, and to fill the transparent liquid between the fiber side end part of the optical system and the fiber end face. It is characterized in that the fiber end surface is cooled with a transparent liquid and the fiber end surface is shielded from air.

Further, the optical transmission apparatus according to the present invention includes an optical system including a light source, a resin-based optical fiber on which light is incident on the end surface from the optical system, and a fiber side end portion of the optical system and a fiber end surface. And a container for cooling the fiber end face with the light-transmitting liquid and for shielding the fiber end face from the air.

According to the present invention, even when a polymer optical fiber is used as the optical fiber and light having a high photothermal energy is incident on the light incident end face of the optical fiber from the light source, the fiber side end of the optical system and the fiber By filling a transparent liquid between the end face and cooling the fiber end face with this transparent liquid and shielding the fiber end face from the air, it is possible to prevent the end face of the optical fiber from being burned.

Here, the outside of the container filled with the translucent liquid may be air-cooled. Further, the translucent liquid may be circulated to the outside for cooling.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the configuration of the optical transmission device according to the first embodiment of the present invention. This optical transmission device includes a housing frame 15 in which the light source 1 is housed, and an optical fiber rod 6 for transmitting illumination light to each part.
Equipped with.

The housing frame 15 is a hollow box body having a vent hole (not shown). Inside the housing frame 15, a light source cooling fan 14, a light source (lamp) 1, a first light source 1
The lens 2, the cold mirror reflection cup 3, and the second lens 4 are arranged.

The fan 14 for cooling the light source sucks the outside air into the housing frame 15 and discharges it to the outside of the frame, and cools the light source 1 by the wind. The light source 1 is a low-volt halogen bulb, and the device of this example (fiber diameter 3 m
m × 19), the output is 65 W. The first lens 2 and the second lens 4 focus the light emitted from the light source 1 toward the optical fiber rod 6. The reflection cup 3 is the first
The light emitted from the lens 2 toward the outer peripheral portion is reflected toward the second lens 4.

An optical fiber unit fixed coupling 13 and an optical fiber unit coupling 12 are attached to the right side surface of the housing frame 15 in the figure. The fixed coupling 13 has a hollow cylindrical shape and is fixed to the side wall 15 a of the housing frame 15. The fixed coupling 13 is arranged coaxially with the optical axes of the light source 1 and the first and second lenses 2 and 4. A hollow cylindrical optical fiber unit coupling 12 is fitted in the fixed coupling 13.
Multiple (19 in this example) in the same coupling 12.
Containing a POF optical fiber. The coupling 12 is slidable in the fixed coupling 13 in the axial direction (horizontal direction in FIG. 1). Coupling 1
The axial position of 2 can be fixed by tightening the fixing screw 13a.

The second lens 4 has a lens fixing adjuster screw 10 in the inner hole at the left end of the coupling 12.
It is stored in the pressed state. A cooling liquid booth 5 and a cooling liquid seal packing 8 are provided behind the second lens 4 of the coupling 12. The booth 5 and the packing 8 will be described in detail later.

The optical fiber rod 6 is formed by assembling 19 optical fibers 6a having a diameter of 3 mm and having a sheath 6b fitted on the outer side thereof. Optical fiber unit coupling 12
The sheath 6b is fitted inside the. Coupling 12
An optical fiber rod adjuster screw 11 is arranged at the right end of the sheath 6b. The screw 11 is a male screw 12a on the outer periphery of the right end of the coupling 12.
It has an inner screw 11a that is screwed into. The inner diameter portion 11b of the screw 11 has a double ring shape extending to the left side in the figure, and pushes the sheath 6b of the optical fiber rod 6 to the left side in the figure. By turning the screw 11, the axial position of the optical fiber rod 6 in the coupling 12 can be determined.

Next, the operation of the optical transmission device shown in FIG. 1 will be described. The light emitted from the light source 1 provided in the housing room 15 passes through the first lens 2 and the second lens 4 and enters the rod 6 including a plurality of resin optical fibers. The light source 1 is, for example, 65 W, which has a high light heat of emitted light, so that strong irradiation can be obtained from the end of the optical fiber.
Use a white halogen bulb. Further, the plurality of resin-based optical fibers 6a are adhered to each other with an adhesive and are fixed in the optical fiber unit coupling 12 by the optical fiber rod adjuster screw 11. A polymer optical fiber is typical as the resin optical fiber.

Here, in order to prevent the focal portion of the incident light at the end portion of the optical fiber from being burnt out, the second lens 4 is used.
The cooling liquid booth 5 is provided between the optical fiber rod 6 and the optical fiber rod 6, and the cooling liquid booth 5 is filled with the cooling liquid which is a translucent liquid. As the cooling liquid, an oil having a high light transmittance and a small transmission loss of a few%, particularly a vegetable-based transparent oil (eg, camellia oil)
Is suitable. Other than camellia oil, optical oil and (mineral oil) are also preferable. This cooling liquid cools the end face of the optical fiber and shields the end face of the optical fiber from the air to prevent oxidation. Although natural heat radiation may be sufficient to cool the heated cooling liquid, it is desirable to provide the fiber cooling fan 16 to forcibly cool the outside of the cooling liquid booth 5. Further, in order to circulate and cool the cooling liquid to the outside, a cooling liquid circulation system as shown in FIG. 3 may be provided, which will be described in detail later.

Referring again to FIG. 1, the coolant booth 5
Is formed by disposing a ring-shaped fixed guide 7 and ring-shaped coolant seal packings 8 on both sides thereof between the second lens 4 and the optical fiber rod 6.
The coolant booth 5 has a diameter of about (27) m.
m, the length is about (12) mm, and about 15 ml of the cooling liquid can be stored. The outer periphery of the fixed guide 7 is contacted and supported so as to be surrounded by the inner periphery of the optical fiber unit coupling 12. The optical fiber unit coupling 12 is movable in the longitudinal axis direction with respect to the optical fiber unit fixed coupling 13 mounted in the housing room 15. Both couplings 12, 1
3 is fixed with a fixing screw 13a at an appropriate position. A cooling liquid extraction port 9 is provided in the upper portion of the fixed guide 7, and a cooling liquid supply groove 13b is provided in a part of the optical fiber unit fixed coupling 13, and a removable lid 13c is mounted thereon. To be The presence of the cooling liquid has the effect of cooling the portion that has generated heat due to the concentration of light at the end of the optical fiber. Further, it is considered that the cooling liquid itself may play a lens-like role, and in that case, there is a secondary effect that it also leads to amplification of light.

FIG. 2 is a view showing a lens having another shape that can be used as the second lens 4 in the optical transmission device according to the first embodiment of the present invention. Instead of a convex lens having a convex portion on the light source side as shown in FIG. 1, a convex lens having a convex portion on the optical fiber side as shown in FIG. 2A or (b)
A concave lens having a concave portion on the light source side as shown in FIG. 7, a convex lens having convex portions on both sides as shown in (c), an asymmetric convex lens as shown in (d), and the combination thereof are used. be able to.

FIG. 3 is a diagram schematically showing a cooling liquid circulation system for circulating the cooling liquid to the outside for cooling in the optical transmission device according to the second embodiment of the present invention. The optical transmission device main body shows a cross section of the cooling liquid booth 5, and the optical fiber rod 6 is visible on the front side. The periphery of the cooling liquid booth 5 is surrounded by the fixed guide 7, the optical fiber unit coupling 12, and the optical fiber unit fixed coupling 13. Therefore, the cooling liquid inlet 1 is attached to the optical fiber unit fixed coupling 13.
3d and the cooling liquid outlet 13e are provided, and the cooling liquid can be circulated to the outside by providing the cooling liquid passage also in the corresponding portion of the optical fiber unit coupling 12 and the fixed guide 7. Coolant outlet 13 of the optical transmission device body
The cooling liquid flowing out of e passes through a condenser 31 provided outside the main body and is cooled by a cooling fan 32 installed adjacent to the condenser 31. The cooled liquid is returned to the cooling liquid inlet 13d of the optical transmission device body by the microcirculation pump 33. In this example, the pump 33
The flow rate is 50 ml / min.

FIG. 4 is a diagram showing an example of a temperature measurement result in the optical transmission device according to the first embodiment of the present invention. As a cooling liquid, 15 ml of camellia oil was used. The test time was 72 hours, and light was continuously emitted during that time. 7
The temperature in the first lens 2 15 mm away from the light source 1 after 2 hours is 135 ° C.
The temperature at the second lens 4 separated by 5 mm was 105 ° C., and the temperature at the end face of the optical fiber 12 mm separated from the second lens by the cooling liquid was 75 ° C. The temperature in the cooling liquid booth 5 was kept at about 65 ° C. on average.
The optical fiber end surface temperature of 75 ° C. was a temperature at which the durability of the POF optical fiber could be maintained.

[0027]

As described above, according to the present invention, even when a polymer optical fiber is used as an optical fiber and light having high photothermal energy is incident from the light source to the light incident end face of the optical fiber, An incident light focal point in the optical fiber is filled by filling a transparent liquid between the fiber side end of the system and the fiber end face, cooling the fiber end face with this transparent liquid, and shielding the fiber end face from the air. It is possible to prevent burning.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an optical transmission device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a shape of another lens that can be used as a second lens 4 in the optical transmission device according to the first embodiment of the present invention.

FIG. 3 is a diagram schematically showing a cooling liquid circulation system for circulating and cooling a cooling liquid to the outside in the optical transmission device according to the second embodiment of the present invention.

FIG. 4 is a diagram showing a temperature measurement result in the optical transmission device according to the first embodiment of the present invention.

[Explanation of symbols]

1 Light Source 2 First Lens 3 Cold Mirror Reflection Cup 4 Second Lens 5 Coolant Booth 6 Optical Fiber Rod 6a Optical Fiber 6b Sheath 7 Fixed Guide 8 Coolant Seal Packing 9 Coolant Extractor 10 Lens Fixed Adjuster Screw 11 Light Fiber rod adjuster screw 11a Inner screw 11b Inner diameter portion 12 Optical fiber unit coupling 12a Male screw 13 Optical fiber unit fixing coupling 13a Fixing screw 13b Cooling liquid supply groove 13c Lid 13d Cooling liquid inlet 13e Cooling liquid outlet 14 Light source cooling fan 15 Housing room 16 Fiber cooling fan 31 Condenser 32 Cooling fan 33 Micro circulation pump

Claims (6)

[Claims] 1. A method for preventing the end surface of a resin-based optical fiber from being burnt out by light incident from an optical system including a light source, the method including a translucency between a fiber-side end portion of the optical system and the fiber end surface. A method for preventing burnout of a resin-based optical fiber, which comprises filling a liquid, cooling the fiber end face with this translucent liquid, and shielding the fiber end face from the air. 2. The method for preventing burnout of a resin-based optical fiber according to claim 1, wherein the outside of the container filled with the translucent liquid is air-cooled. 3. The method for preventing burnout of a resin-based optical fiber according to claim 1, wherein the translucent liquid is circulated outside to be cooled. 4. An optical system including a light source, a resin-based optical fiber on which light from the optical system is incident on an end face, and a translucent liquid is filled between a fiber side end of the optical system and the fiber end face. An optical transmission device comprising: a container for cooling the fiber end surface with a translucent liquid and for shielding the fiber end surface from air. 5. The optical transmission device according to claim 4, further comprising means for air-cooling the outside of the container filled with the translucent liquid. 6. The optical transmission device according to claim 4, further comprising means for circulating the translucent liquid to the outside to cool it.