JPH0483202A - infrared optical fiber - Google Patents

Abstract

PURPOSE:To maintain transmitting ability of 20W which is required for laser operation for 10 hours by limiting solid foreign matter which is contained to only <=3mum size. CONSTITUTION:This infrared optical fiber is used for the transmission line of a laser machine or laser treatment device and consists of 30 - 70wt.% silver chloride and 70 - 30wt.% silver bromide and the size of the contained solid foreign matter is <=3mum. When laser light is transmitted continuously, partial deterioration does not advance up to the deterioration (burning) of the infrared optical fiber on condition that the solid foreign matter in the infrared optical fiber material is of <=3mum. Consequently, the infrared-ray fiber is obtained which is small in deterioration due to the continuous transmission of laser light and has long-time operation life while the operation life can be predicted for laser power in use.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an infrared optical fiber used as an optical transmission line in a laser processing machine or a laser treatment device.

Conventional technologyIn laser processing and laser surgery, various laser beams are used depending on the purpose. CO2 laser light is used because it is superior.

ILCO as a means to guide C○2 laser light to the target area
2 Laser light has a wavelength of 10.6 μm and belongs to mid-infrared light, and cannot be transmitted through quartz optical fibers used for communications. Conventionally, a mirror-joint light guide path that combines mirrors has been used. However, since the mirror joint light guide path is difficult to operate when performing precise surgery, attempts have been made to replace it with an infrared optical fiber.Halogenated infrared optical fiber materials that transmit LCO2 laser light well are recommended. Metal crystals generally have poor mechanical bending properties and are prone to breakage. A crystalline infrared optical fiber consisting of silver oxide and silver bromide (
JP 1-209407) has been developed, and it can not only be replaced with a mirror joint light guide, but also inserted into the body together with an endoscope to guide CO2 laser light to the affected area, allowing treatment inside the body without open surgery. The so-called “CO2
Application to laser endoscopes is becoming possible.

Problems to be Solved by the Invention When a silver chloride-silver bromide infrared optical fiber (φ0.3 mm) described in JP-A-1-209407 is fabricated and a long-time laser beam (input 20 W) is transmitted through it, the result shown in FIG. As shown in Figure 2, there is a large variation between 0 and 100 hours, and there is a phenomenon of deterioration (burnout). Considering the surgical time with an f2cO2 endoscope, an operating life of 10 hours or more is required, including margins. , Deterioration of infrared optical fiber during laser transmission is a major issue in realizing a CO2 endoscope.

Furthermore, in order to apply infrared optical fibers to processing machines for industrial use, even harsher continuous transmission capabilities are required, and the transmission time is on the order of several months (
The operating life of the laser light must be 1000 hours). The conventional method of determining the quality of infrared optical fibers based on their transmission life is to multiply the initial transmittance, transmission capacity, etc. by an appropriate safety factor, because the cause of the decline in transmission capacity over time is unknown. The object of the present invention (in view of the above-mentioned problems) is to have a long operating life with little deterioration due to continuous transmission of laser light, and to have a long operating life with respect to the laser power used. The aim is to provide an infrared optical fiber that can predict the amount of silver chloride.Means for solving the problem Weight: 70 to 30% by weight of silver bromide, and the size of solid foreign matter contained: 3
It should be less than μm.

In addition, the composition ratio of the infrared optical fiber consisting of silver chloride (AgCl) and silver bromide (AgBr) is set to 30 to 70% by weight.
Silver bromide is 70 to 30% by weight, and the end face of the infrared optical fiber is annealed (for example, in a nitrogen atmosphere for 150'Cl2O hours).
The crystal grain size is enlarged to 20 μm or more.

Effects of the present invention is that during continuous transmission of laser light, if the solid foreign matter in the infrared optical fiber material is 3 μm or less, the progress of partial deterioration will not reach the point of deterioration (burnout) of the infrared optical fiber. Based on findings.

In addition, the annealed end face does not undergo deterioration over time such as granulation of the end face that is seen during continuous transmission of laser light.
Infrared optical fibers can transmit laser light for long periods of time.

EXAMPLE A method for manufacturing an infrared optical fiber according to the present invention and its characteristics will be explained in detail with reference to the drawings.

As shown in Figure 2, a crystal material was prepared with a composition ratio of silver chloride and silver bromide of 30 to 70% by weight of silver chloride, which has high mechanical strength, and a single crystal was created using the Bridgman method. An infrared optical fiber 1 is manufactured using the extrusion device shown in FIG.
This is a mother crystal formed into a cylinder of m.

3 is a pressure label; 4 is a die having a nozzle 5 that determines the fiber diameter; the nozzle diameter is φ0.3 to 0;
The die 4 is made of silicon nitride ceramic material, which is hard to corrode against halogenated materials and has high hardness. 6 is a container that stores the preform, and 7 is a heater that controls heating of the container 6. The weight 8 is for applying a tensile load to the infrared optical fiber.

The extrusion procedure for infrared optical fiber is as follows: First, preform 2
is stored in the container 6, and after the temperature of the container 6 stabilizes at 220 (t) by heating control of the heater 7.
The infrared optical fiber 1 was compressed to 10 (ton/cm2)"-15 (
The weight 8 had a weight in the range of more than the yield strength and less than the tensile strength of the infrared optical fiber.
φ0. The above load range of 300 (g) is appropriate for an infrared optical fiber of 3 (mm).

Next! Investigate the effect of foreign matter in the infrared optical fiber on the operating life.
rrK l 6pm, 3μm), A120s (10
Use carbide and oxide powders with different sizes (μm) and metal powders of iron, aluminium, and tin (40μm or less). After adhering these powders to the outer surface of preform 2, they are extruded to form fibers. It was confirmed that each of the powders were mixed into the manufactured infrared optical fibers by external inspection using a microscope R1.Using these infrared optical fibers, &
An experiment was conducted to find the correlation between CO2 laser power and laser transmission life.The experiment was conducted by keeping the laser input constant and measuring the time (life) until the infrared optical fiber deteriorates (burned out).Figure 1 shows the experimental results. show.

Infrared optical fiber mixed with metal powder undergoes a chemical reaction at the point where it is attached before the laser beam is introduced, resulting in discoloration and melting, making it impossible to carry out laser transmission experiments.This phenomenon is especially noticeable when humidity is high. Infrared optical fibers can melt just by touching aluminum under high humidity, so it is important to eliminate metal powders that have an ionization potential lower than that of silver in the infrared optical fiber production environment.

The following explanation will explain the contamination of carbides and oxides. When 40 μm silicon carbide foreign matter was mixed in, the power resistance was significantly reduced and IOW could not be transmitted. When the deteriorated infrared optical fiber was observed under a microscope, foreign matter was found in all the deteriorated parts. Upon closer observation, it was found that the infrared optical fiber material around the foreign object was melting.This may be due to the fact that the foreign object absorbs the laser beam, and the heat generated by the foreign object melts the surrounding infrared optical fiber material, which causes deterioration ( It is thought that this resulted in burnout. More importantly, a device that withstood 10 hours with 2.5W input was able to withstand only 4 minutes with 7.5W input, etc.There was a correlation between laser input and laser transmission life. By the conventional identification method (Friend initial 7)
．． Judging only the power resistance of 5W and multiplying 7.5W by an appropriate safety factor (for example 0.8), when used continuously (laser input 6W), deterioration will occur at about 10 degrees. It will end up being put away. It is thought that such a decrease in transmission capability over time occurs because the infrared optical fiber material around the foreign object gradually melts. Furthermore, there is a correlation between the particle size of foreign particles and the laser transmission life.For example, if a life of 1 hour is set, at l'L 40μm, it is approximately 5W, 16
It was found that the larger the particle size of the foreign material, the shorter the life was, as it was about 20W110 for μm and about 40W for 3μm.
This is thought to occur because the progress of melting of the infrared optical fiber material around the foreign object is proportional to the size of the foreign object, that is, the amount of heat absorbed by the foreign object. Previously, it was known that if foreign matter was mixed into an infrared optical fiber, the initial power resistance would be reduced (although it was not known what kind of effect it would have on the lifespan).This experimental result shows that foreign matter can interfere with laser transmission. As shown in Figure 4, it is clear from the above results that this is one factor that determines lifespan. It is possible to achieve a long transmission life if the fiber does not contain metal particles with an ionization potential lower than that of silver, and does not contain foreign particles larger than 3 μm, such as metal grains, oxides, nitrides, and carbides, which have an ionization potential higher than that of silver. Become.

Saraban 2: In order to use it in a laser processing machine, etc., it is necessary to have a lifespan of 1000 hours. In this case, as shown in Figure 4, the infrared optical fiber must contain foreign particles larger than 0.1 μm. achievable if

In conventional manufacturing methods that do not control the removal of foreign matter, non-metallic foreign matter and metal powder of several tens of microns may be mixed in during the extrusion molding process, and free silver of several microns to several tens of microns may remain during the crystal formation process using the Bridgman method. As shown in the conventional example, the strength of the life characteristics with large variations was observed.Careful cleaning of used parts to eliminate the possibility of contamination with metal powder.Furthermore, RAP uses a crystal growth method in an iodine atmosphere to reduce free silver. Even in a process in which improvements have been made to extend the life of the infrared optical fiber, as shown in FIG. 5, deterioration occurs after about 100 to 140 hours. If we closely observe this situation, we can see that the majority of the deterioration is at the end face of the infrared optical fiber, which is a phenomenon different from that caused by foreign matter.Therefore, the following experiment was conducted using the Asahi Sunawa board. The end face was observed under an electron microscope after being subjected to time transmission and before it deteriorated.The end face after transmission showed a phenomenon of granulation, and it was found that the surface gradually became rougher. It is thought that deterioration and burnout occur due to heat absorption from the laser. The observed grain size was 1-2 μm,
This was about the same as the crystal grain size of the original infrared optical fiber.The cause of this grain formation is unknown.Assuming that the crystal grain size at the end face is related to the transmission life of the infrared optical fiber, 20 at 150 degrees in nitrogen atmosphere
Go to annealing time and check the transmission life.Here, the end face crystal grain size of this infrared optical fiber is increased by annealing from 1 to 1.
By annealing the end face as shown in Fig. 5, 3.
It has become clear that a transmission life of 400 hours, which is more than twice as long, can be achieved, and that a longer life can be achieved. An infrared optical fiber that does not contain contaminants larger than 3 μm such as nitrides and carbides can maintain the 20 W transmission capacity required for laser surgery for 10 hours.

Furthermore, when used in a laser processing machine that requires a life of 1000 hours, li 0. 1. This can be achieved if the infrared optical fiber does not contain foreign particles larger than am.Also, by keeping the crystal material and molding method constant, the size of the foreign particles contained in the infrared optical fiber can be determined (
Dai: Since we can understand the relationship between laser input and transmission life, we can reliably judge whether the infrared optical fiber is good or bad in terms of transmission life.

In addition, by enlarging the crystal grain size of the end face of the infrared optical fiber to 20 μm or more by annealing (for example, in a nitrogen atmosphere at 150°C for 120 hours), it is possible to prevent granulation of the end face that would cause a decrease in transmission capacity. Therefore, the life of the infrared optical fiber can be further extended.

Effects of the Invention According to the present invention, by limiting the solid foreign matter contained to only those smaller than 3 μm, the transmission capacity of 20 W required for laser surgery can be maintained for 10 hours.

Mana By annealing the end face of the infrared optical fiber to enlarge the crystal grain size to 20 μm or more, it is possible to prevent granulation of the end face, which causes a decrease in transmission capacity, and further extend the life of the infrared optical fiber. can be achieved.

[Brief explanation of drawings]

Figure 1 shows the characteristics showing the relationship between the size of foreign particles, laser input and laser transmission life in one embodiment of the present invention. Figure 2 shows the silver bromide concentration weight of a silver chloride-silver bromide single crystal. Characteristics showing the yield strength/tensile strength of the crystal and the tensile strength of the infrared optical fiber with respect to % @ Figure 3 is a schematic cross section of the manufacturing equipment of the infrared optical fiber manufacturing method in one embodiment of the present invention @
FIG. 4 is a characteristic diagram showing the relationship between the diameter of mixed foreign matter and laser transmission life. FIG. 5 is a characteristic diagram showing the relationship between the transmission life of a conventional infrared optical fiber and an infrared optical fiber of the present invention for a laser input of 20 W. 1... Infrared light phino < 2... Preforma
4...Die included 8...Swing

Claims (5)

[Claims] (1) The composition ratio of the infrared optical fiber consisting of silver chloride (AgCl) and silver bromide (AgBr) is 30 to 70% by weight of silver chloride,
An infrared optical fiber characterized by containing 70 to 30% by weight of silver bromide and containing solid foreign matter having a size of 3 μm or less. (2) Solid foreign substances contained in infrared optical fibers include oxides such as aluminum oxide and silicon oxide, nitrides such as silicon nitride, carbides such as silicon carbide, or substances with an ionization potential higher than silver such as silver and gold. Claim 1 characterized in that the metal has
Infrared optical fiber described in . (3) The composition ratio of the infrared optical fiber consisting of silver chloride (AgCl) and silver bromide (AgBr) is 30 to 70% by weight of silver chloride,
An infrared optical fiber characterized in that silver bromide is 70 to 30% by weight, and the end face of the infrared optical fiber is annealed to enlarge the crystal grain size to 20 μm or more. (4) The infrared optical fiber according to claim 3, wherein the size of the solid foreign matter contained is 0.1 μm or less. (5) Solid foreign substances contained in infrared optical fibers include oxides such as aluminum oxide and silicon oxide, nitrides such as silicon nitride, carbides such as silicon carbide, or substances with an ionization potential higher than silver such as silver and gold. Claim 4 characterized in that the metal has
Infrared optical fiber described in .