JPH05188225A - Hollow waveguide for uv laser beam - Google Patents

Abstract

PURPOSE:To provide a hollow waveguide for UV laser beam which enables efficient transmission of UV rays through a small diameter. CONSTITUTION:A resin film layer 2 which can efficiently transmit UV rays is formed on the outside of a hollow glass pipe 3 consisting of a glass material of a synthetic quartz, etc., having a high transmittance for UV rays and besides a metallic film layer 1 consisting of a metallic material of Al, etc., having a high reflectance for UV rays is formed on the outside of the resin film layer 2 and while the laser beam in an UV region is reflected by the inner surface of the glass pipe 3 and by the boundary surface of the resin film layer 2 and the metallic film layer 1, it is transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet laser light hollow waveguide for transmitting an ultraviolet laser light having a wavelength in the ultraviolet range.

[0002]

Laser light having a wavelength in the ultraviolet region, for example, laser light such as excimer laser has high energy,
Its application range is extremely wide, such as Nereza CVD, surface modification, and photochemical synthesis.

Since these laser lights have a short peak wavelength and a large peak power and are harmful to the living body, it is possible to safely transmit the laser lights to a remote place. It becomes an indispensable condition when applying to.

Conventionally, there have been the following methods for transmitting a laser beam having a wavelength in the ultraviolet range, for example, a laser beam such as an excimer laser. (1) Method using a silica-based solid fiber for ultraviolet light As shown in FIG. 3, a silica glass having a good transmittance for light in the ultraviolet region is used as a core 11, and a clad 12 surrounding it.
For this purpose, quartz glass, which is doped with impurities such as fluorine and whose refractive index is smaller than that of the core, is used to transmit the light while reflecting the light at the boundary surface between the core 11 and the clad 12.

(2) Hollow Waveguide Method This is of the type disclosed in Japanese Patent Application No. 1-54567, and as shown in FIG. A metal film layer 21 made of aluminum or the like having a high reflectance with respect to ultraviolet light is formed on the outer surface of a good quartz glass tube 22, and the inner surface of the quartz glass tube 22 and the outer surface metal film layer of the quartz glass tube 22 are formed. The laser light having an ultraviolet wavelength is reflected while being transmitted at the boundary surface with 21.

[0006]

However, the above-mentioned conventional method (1) using a solid quartz fiber can transmit weak ultraviolet light, but when trying to transmit light of a certain intensity or more, laser light is transmitted. Destruction at the end face where L is incident,
This causes so-called end face destruction, making transmission impossible. If a large number of fibers are used for transmission, it is possible to transmit a certain amount of light, but the bundle diameter becomes large, which makes it difficult to insert the fibers into a blood vessel in the field of medicine and the like.

On the other hand, (2) the method using the hollow waveguide has a hollow fiber structure, and the inside of the quartz glass tube 22 and the outer surface of the quartz glass tube 22 and the boundary surface between the metal film 21 are in the ultraviolet region. It is intended to transmit the laser light of the wavelength of while reflecting, and it is effective as an ultraviolet light guide path.

However, in order to manufacture a hollow fiber having an outer diameter of a certain value or less, it becomes necessary to carry out a drawing process. At this time, as in the case of solid fiber production, when the outer surface is not coated with, for example, a polyimide resin immediately after drawing, when exposed to air,
Fibers can easily break due to defects during drawing. If the resin layer absorbs ultraviolet rays, the advantages of the hollow ultraviolet optical waveguide are lost.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to eliminate the above-mentioned problems and provide a hollow waveguide for ultraviolet laser light capable of effectively transmitting ultraviolet light with a small diameter. .

[0010]

To solve the above problems, the present invention provides a resin film layer capable of effectively transmitting ultraviolet light to the outside of a hollow glass tube made of a glass material having a high transmittance for ultraviolet light. A metal film layer having a high reflectance to ultraviolet light is formed on the outside of the resin film layer, and the laser light in the ultraviolet region is formed on the inner surface of the glass tube and the interface between the resin film layer and the metal film layer. It is characterized by transmitting while reflecting.

[0011]

As described above, by forming a resin film layer capable of effectively transmitting ultraviolet light on the outside of the hollow glass tube, the resin film layer capable of effectively transmitting ultraviolet light can be formed on the hollow glass tube. Since it is used as a resin layer for drawing, a very thin (for example, 0.4 mm or less) hollow synthetic quartz tube can be manufactured, and a metal film having a high reflectance for ultraviolet light should be formed on the outer surface of this tube. This makes it possible to construct a hollow waveguide for ultraviolet light.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a hollow waveguide for ultraviolet laser light according to the present invention. As shown in the figure, the waveguide 4 can effectively transmit ultraviolet light to the outer surface of the glass tube 3 made of a glass material having a high transmittance for ultraviolet light, for example, synthetic quartz, by an appropriate method. A thin film layer 2 of a resin, for example, a transparent fluororesin “CYTOP” (trademark registration pending) manufactured by Asahi Glass Co., Ltd. is formed, and CVD is performed on the outer surface of the resin film layer 2.
The metal film layer 1 is formed of a metal material having a high reflectance with respect to ultraviolet light, for example, an aluminum material, by an appropriate method such as PVD or vacuum deposition. The glass tube 3 has a wall thickness of about 0.1 mm, the resin film layer 2 has a wall thickness of 1 micron or less, and the metal film layer 1 has a wall thickness of several microns.

FIG. 2 is a diagram for explaining how the laser light is transmitted through the glass tube 3 of the waveguide 4 having the above structure. As shown in FIG. It is reflected on the inner surface of the tube 3. Part of the light passes through the glass tube 3 and the resin film layer 2, and is transmitted while being reflected at the boundary surface between the resin layer 2 and the metal film layer 1. Since the resin film layer 2 is transparent to ultraviolet rays as described above, it is possible to suppress the loss when the laser light passes through this layer to be low.

By constructing the waveguide 4 as described above, a resin film layer capable of effectively transmitting ultraviolet light is formed on the outside of the hollow glass tube, so that the waveguide 4 has a very small diameter (eg, It can be manufactured as a hollow synthetic quartz tube.

[00115]

As described above, according to the present invention, a very thin hollow waveguide can be manufactured by coating the outer surface of the glass tube with the ultraviolet light transmitting resin, and the outer surface of the hollow waveguide can be manufactured. By forming a metal film having a high reflectance, it is possible to obtain an excellent effect that it is possible to obtain a waveguide having a small diameter and capable of effectively transmitting ultraviolet light.

[Brief description of drawings]

FIG. 1 is a sectional view of a hollow waveguide for ultraviolet laser light according to the present invention.

FIG. 2 is a diagram for explaining how laser light is transmitted through a hollow waveguide for ultraviolet laser light in FIG.

3A and 3B are diagrams showing a conventional silica-based solid fiber for ultraviolet light, in which FIG. 3A is a sectional view and FIG. 3B is a diagram for explaining how laser light is transmitted.

FIG. 4 is a cross-sectional view showing a configuration of a conventional hollow waveguide.

[Explanation of symbols]

 1 metal film layer having high reflectance for ultraviolet light 2 resin film layer having high transmittance for ultraviolet light 3 glass tube having high transmittance for ultraviolet light 4 waveguide

Claims (1)

[Claims] 1. A resin film layer capable of effectively transmitting ultraviolet light is formed on the outside of a hollow glass tube made of a glass material having a high transmittance for ultraviolet light, and further ultraviolet light is provided on the outside of the resin film layer. On the other hand, a metal film layer having a high reflectance is formed, and ultraviolet rays are transmitted while reflecting the laser light in the ultraviolet region at the inner surface of the glass tube and the boundary surface between the resin film layer and the metal film layer. Hollow waveguide for laser light.