JPS604906A - Optical fiber cable - Google Patents

Abstract

PURPOSE:To easily constitute an optical system which copes with the elongation of an optical fiber and to reduce the system in size by allowing an optical system holding member near a projection terminal to expand an contract according to the thermal expansion of the optical fiber. CONSTITUTION:The optical fiber 4 and a pipe 12 are free at the projection terminal side and the elongation of the optical fiber due to heat generation appears at the projection side. The holding member 13 which holds the 2nd condenser lens 5 is fixed to the projection side of the pipe 4 by being adhered or pressed in. When laser light 1 is incident on the optical fiber 4, the optical fiber 4 elongates as shown by an arrow 4 owing to heat generation. At this time, the pipe 12 also elongates as shown by the arrow 14 under the influence of the heat of the optical fiber 4, leak light of the laser light 1, etc. The 2nd condenser lens 5 fixed to the pipe 12 moves in the direction of the arrow 14 as a matter of course, and consequently the distance 15 between the projection terminal surface of the optical fiber 12 and the 2nd condenser lens 5 does not vary much and the optical position relation is unchanged.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical fiber cable used in laser scalpel devices, laser processing machines, and the like.

Conventional configurations and their problems For example, there is KRS-5 as a material for optical fibers for CO2 laser light, but when CO2 laser light is transmitted through this optical fiber, the optical fiber generates heat due to absorption and other factors, and thermal expansion causes the fiber to emit heat in the longitudinal direction. Elongation occurs. To explain this gate opening with reference to Figure 1, the laser beam 1
The light is guided and incident on the end face of the optical fiber 4 while being focused by the condenser lens 2, reflection mirror 3, and the like. The incident laser light 1 is emitted from the other end of the optical fiber 4, and the laser light 1 is focused by the second condenser lens 6 and irradiated onto the irradiation section 6.

At this time, the optical fiber 4 generates heat as described above and stretches in the longitudinal direction. If the input and output ends of the optical fiber 4 are fixed, this elongation will cause waviness in the portions that are not fixed by the amount of elongation, causing transmission efficiency bagging and the like. Also, if one of the input and output ends is fixed and the other is left free, the end face in the IJ - state will stretch and shift its position, so the first condensing lens 2 or the second The optical position of the condensing lens 5 changes, resulting in problems such as a decrease in power due to a decrease in transmission efficiency and a decrease in power density due to the inability to obtain the minimum focusing diameter.

As a countermeasure to this problem, a method has been considered in which the position of the incident end face of the optical fiber 4 is measured using another laser beam (He-Ne laser, etc.) and the input optical system is moved to control the laser beam focal position, but the configuration is It's complicated. As described above, heat generation in optical fibers causes various problems, and in order to prevent this, it is possible to use cooling fluid, but it is effective in preventing burnout and deterioration of optical fibers due to heat generation, that is, to prevent heat generation to a certain extent. However, the flow rate is limited by the size of the optical fiber cable and the influence of jets on the irradiation area, and is insufficient to eliminate elongation due to heat generation. Furthermore, the longer the optical fiber,
Neither method was effective because the elongation increased due to a small amount of heat generation.

Purpose of the Invention In view of the above-mentioned problems, an object of the present invention is to provide an optical fiber cable that has a simple configuration that can accommodate the elongation of optical fibers, and is also miniaturized and can be applied to endoscopes. It is something.

DESCRIPTION OF THE INVENTION According to the present invention, an optical system holding member near the output end of an optical fiber is configured to be expandable and contractible in response to thermal expansion of the optical fiber.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 2, 3, and 4.

FIG. 2 is an overall view of a laser irradiation device 8 using the optical fiber cable 7 of the present invention. A laser light oscillator (not shown) for oscillating laser light is incorporated inside the laser irradiation device 8 . fiber optic cable 7
is the flexible tube 9 and the main body joint part 10.
・Schematically consists of a piece 11. FIG. 3 is a diagram showing a side cross section of the fiber cable 7, and shows the optical fiber 4.
is inserted into a pipe 12 made of a material with a high coefficient of expansion such as aluminum, gold, copper, etc. At the input end side, the optical fiber 4 and the pipe 12 are fixed to a joint portion 10 shown in FIG. 2. (Not shown) - On the blade output end side, the optical fiber 4 and the pipe 12 are in a free state, and the elongation of the optical fiber 4 due to heat generation occurs on the output side. A holding member 13 that holds the second condensing lens 6 is fixed to the output side of the pipe 4 by adhesive, press-fitting, or the like. Here, when the laser beam 1 begins to enter the optical fiber 4, the optical fiber 4 extends in the direction of the arrow 14 due to heat generation. However, at this time, the pipe 12 also generates heat due to the heat of the optical fiber 4 and the leakage light of the laser beam 1, and extends in the direction of the arrow 14. Naturally, the second condensing lens 5 fixed to the pipe 12 also moves in the direction of the arrow 14, and as a result, the optical fiber 4
The distance 16 between the output end face and the second condensing lens 6 does not change slightly, and the optical positional relationship does not deviate.

Furthermore, if only the holding member 13 is made of a material (such as plastic) that has a sufficiently large coefficient of expansion relative to the optical fiber 4, the pipe 12 does not need to be made of a material with a high coefficient of expansion.

FIG. 4 is a side sectional view without showing the optical fiber cable in another embodiment of the present invention, in which the holding member 13' is constructed in a bellows shape, and by increasing the length of the holding member 13' within a short range, the holding member 13' is expanded. It is also possible to configure it so that there is a margin for the coefficient.

Effects of the Invention As described above, the present invention allows the holding part to expand and contract in response to the thermal expansion of the optical fiber, so that the emitting end of the optical fiber and the second condenser are always protected against the elongation caused by heat generation of the optical fiber. It is possible to maintain the optical positional relationship of the optical lenses and eliminate deterioration, burnout, etc. of two optical fibers without reducing the transmission efficiency of laser light. Furthermore, since it can be used without using a cooling fluid, it is also effective for use inside the human body where cooling fluid cannot be used in the irradiation part, and its small size makes it very valuable.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional optical fiber cable, Figure 2 is a perspective view of a laser irradiation device using the optical fiber cable of the present invention, and Figure 3 is an optical fiber cable output section in an embodiment of the present invention. FIG. 4 is a cross-sectional view of an optical fiber cable output part in another embodiment of the present invention. 1...Laser light, 4...Fufuiha, 7...Optical fiber cable, 12...
... Pipe, 13... Holding member. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 0 @Figure 3

Claims (3)

[Claims] (1) A laser beam condensing lens provided near the output end of the optical fiber, a holding member that holds the condensing lens, and the holding member being expandable and contractible in accordance with the thermal expansion of the optical fiber. fiber optic cable. (2) The optical fiber cable according to claim 1, wherein the holding member is made of a material with a high coefficient of expansion. (3) An optical fiber is inserted into a pipe having an inner diameter approximately equal to an outer diameter of the optical fiber, a holding member is fixed to the pipe, and the pipe is made of a material having an expansion coefficient similar to that of the optical fiber. An optical fiber cable according to claim 1.