JP2754297B2 - Optical fiber for laser treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a laser treatment for fiber-optic used for intraocular photocoagulation, simple
The structure provides less adverse effects due to over-coagulation or non-coagulation.

[0002]

2. Description of the Related Art Generally, the refractive index distribution of an optical fiber is represented by two types, a step type and a graded type.
The optical fiber used for intraocular photocoagulation is of the step type. The reason for this is to use a method of coagulating with light so as to punch a tablet in a retinal detachment surgery or the like. At this time, the coagulation range needs to be uniformly coagulated at a point (circular shape). A step type with a relatively uniform power distribution has been used.

[0003]

However, even if it is a step type, the emission pattern (intensity distribution) of the laser beam is not a perfect step type at all, and the intensity at the center is high and the outline at the outer periphery is not clear. Distribution tends to occur, and as a result, the central part becomes over-solidified, and in the worst case, there is a fear of a hiatus. In addition, if the output of the laser beam is lowered to the central part to avoid this overcoagulation, the strength of the peripheral part becomes too low and it may remain uncoagulated. Would.

[0004]

SUMMARY OF THE INVENTION This invention, which is emitted pattern of the laser light from the above viewpoints and to provide a uniform fiber-optic, the invention according to claim 1, its features in the center A core having a refractive index distribution lower than the surrounding refractive index, a cladding located outside the core, the refractive index of which is lower than the minimum refractive index of the core, and the core and the cladding. An optical fiber for laser treatment comprising an intermediate portion and an intermediate portion having a lower refractive index than that of the cladding, and an emission pattern of laser light incident on the optical fiber being substantially uniform. It is.

[0005]

The refractive index at the center of the core is lower than that around the core, and the emission intensity of the laser beam is reduced over the entire cross section of the core.
Pot because it is designed to be uniform hypercoagulability, there is no possibility of non-solidified.

[0006]

FIG. 1 shows a refractive index distribution of an optical fiber according to the present invention. In the figure, 1 indicates the refractive index of the core portion, and the refractive index of the central portion of each of the core portions is lowered. In the drawing, reference numeral 2 denotes a refractive index of the clad portion, and reference numeral 3 denotes a refractive index of an intermediate portion between the core portion and the clad portion, which is lower than the refractive index of the clad portion. Figure 2 shows the emission pattern of the incident laser light to the optical fiber of FIG. 1, the core
Shows a nearly uniform emission pattern over the entire surface of
Ri, is keeping the sharpness even at its periphery. This
Of the optical fiber, by using a laser treatment, such as intraocular photocoagulation, hypercoagulable and the central portion, relapsing it can be clinically very effective results to prevent by coagulation insufficient peripheral portion is obtained.

Next, a method of manufacturing the optical fiber having the refractive index distribution shown in FIG. 1 will be described. First, a central core portion is manufactured by a VAD method. That is, supported vertically,
The burner is made to face the lower end of the rod-shaped starting member rotating around its axis from obliquely downward, and GeCl ₄ + SiCl ₄ and O ₂ , H ₂ are supplied into the burner to perform flame hydrolysis. Then, a soot composed of GeO ₂ -doped SiO ₂ is deposited on the tip of the starting member by a thermal oxidation reaction to form a preform. Since the burner is opposed to the axis of the starting member at a predetermined angle, a temperature distribution is naturally formed in the tip of the starting member in the radial direction, and the amount of the glass raw material gas, oxygen, hydrogen, and the burner position ( fallen core center part of FIG. 3 What adjustment coupled with the distance) of the starting member
As a result, a preform having a refractive index distribution whose peripheral portion gradually decreases can be obtained. After sintering and stretching this preform, the outer periphery is etched with a plasma flame.
4 is a step-shaped core material having a sharp rise. Next, a fluorine-doped SiO ₂ intermediate portion is formed around the core material by an external method. Finally, the same way the optical fiber preform and without forming a SiO ₂ cladding portion, the optical fiber having a by melt drawing the refractive index distribution shown in FIG. 1 it around the intermediate portion. The power distribution at the exit end of this optical fiber is as shown by the broken line in FIG. 2 and is almost uniform over the entire core, and is close to the ideal of a step type in which the periphery of the core is sharp.

[0008]

As described above, the optical fiber of the present invention is such that the emission pattern of the incident laser light is made substantially uniform in the core by lowering the refractive index at the center of the core as described above. It is suitable for use in intraocular photocoagulation .

[Brief description of the drawings]

FIG. 1 is a refractive index distribution diagram of an optical fiber according to the present invention.

FIG. 2 is an emission pattern of laser light incident on the optical fiber of FIG.

FIG. 3 is a refractive index distribution diagram of a core obtained by a VAD method.

FIG. 4 is a refractive index distribution diagram of an optical fiber obtained by etching a peripheral portion of a core.

[Explanation of symbols]

 1 Refractive index of core part 2 Refractive index of clad part 3 Refractive index of intermediate part

Continuation of the front page (51) Int.Cl. ⁶ identification code FI G02B 6/02 G02B 6/18 6/18 6/22 6/22 A61F 9/00 511 (56) References JP-A-51-134137 (JP) JP-A-52-38941 (JP, A) JP-A-52-106748 (JP, A) JP-A-62-187133 (JP, A) JP-A-2-201403 (JP, A) 5-2104 (JP, U) JP-B-59-3944 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 6/16 A61F 9/007 C03B 20/00 C03B 37 / 012 C03C 13/04 G02B 6/02 G02B 6/18 G02B 6/22

Claims (1)

(57) [Claims] 1. A core having a refractive index distribution in which a refractive index at a central portion is lower than a refractive index around the core, and a core located outside the core.
And the refractive index is lower than the minimum refractive index of the core.
Lad, located between the core and the cladding,
The cladding has a lower refractive index than that of the cladding.
That the laser a therapeutic optical fiber, and emits pattern substantially uniform laser treatment optical fiber of the laser light incident on the optical fiber.