JP2005227707A - Hollow waveguide and its application device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow waveguide that can vary a transmissible wavelength band of light and an output intensity during the use, and also to provide its application device. <P>SOLUTION: The hollow waveguide 1 has a metallic layer 3 composed of gold, silver, copper, aluminum, etc. formed on the interior surface of a glass capillary tube 2, and a dielectric layer 4 composed of an inorganic or organic resin formed on the inner surface of the metallic layer 3. The dielectric layer 4 is formed in such a manner that the thickness is different depending on the circumferential direction θ. As a result, since the transmission characteristic varies by selecting a thickness of the light-transmitting dielectric layer, the transmissible wavelength band of light and the output intensity can be varied during the use. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hollow waveguide and its application device used in the medical field such as dental treatment and surgery, and in the industrial field such as metal processing and surface modification. The present invention relates to a hollow waveguide capable of changing an output intensity and an application device thereof.

  In recent years, in the medical field such as dental treatment and surgery, and in the industrial field such as metal processing and surface modification, a high-power laser has been attracting attention as a medical device or a processing device. A flexible glass hollow waveguide has been proposed.

  FIG. 6 shows an example of the conventional hollow waveguide. The hollow waveguide 1 is configured such that a metal layer 3 is provided on the inner surface of a glass capillary tube 2 and a dielectric layer 14 is provided on the inner surface of the metal layer 3 (see, for example, Patent Document 1).

According to this configuration, since the metal layer 3 is formed on the inner surface of the glass capillary tube 2, the reflectance on the inner surface of the tube is improved, and the inner surface reflectance is further increased due to the light interference effect on the dielectric layer 14. Therefore, the loss of transmitted light can be greatly reduced.
JP 2003-114344 A ([0008], FIG. 1)

  However, according to the conventional hollow waveguide, the thickness of the dielectric layer is optimized with respect to the wavelength of light to be transmitted. However, since the thickness is uniform, the wavelength of light to be transmitted is changed during use. It is not possible. In addition, in order to transmit light having a wavelength different from the planned wavelength, it is necessary to separately prepare a hollow waveguide having a dielectric layer thickness suitable for the wavelength.

  Therefore, an object of the present invention is to provide a hollow waveguide capable of changing the wavelength band and output intensity of light that can be transmitted during use, and an application device thereof.

  In order to achieve the above object, the present invention provides a hollow waveguide in which a metal layer is provided on the inner surface of a tube, and the dielectric layer is provided on the inner surface of the metal layer. Provided is a hollow waveguide characterized by being different.

  A glass capillary tube may be used as the tube.

The thickness t in the circumferential direction θ of the dielectric layer has a maximum thickness t ₁ and a minimum thickness t ₂ .
t = t ₂ + (t ₁ -t ₂ ) · | cos (nθ / 2) | (where n is 1 or 2)
You may comprise so that it may be represented by.

  The metal layer is preferably formed from gold, silver, copper or aluminum.

  In order to achieve the above object, the present invention provides a metal pipe having a bent portion at least at one place in advance or at the time of use, and is inserted into the metal pipe, and a metal layer is provided on the inner surface of the tube. A hollow waveguide application device comprising a hollow waveguide having a dielectric layer embedded therein, wherein the dielectric layer of the hollow waveguide has a thickness different in the circumferential direction. provide.

  According to the hollow waveguide of the present invention, since the transmission characteristics change by selecting the thickness of the dielectric layer that transmits light, the wavelength band and output intensity of light that can be transmitted during use can be changed. It becomes possible.

  By using a glass capillary tube as the tube, it becomes easy to produce a long hollow waveguide.

The thickness t in the circumferential direction θ of the dielectric layer has a maximum thickness t ₁ and a minimum thickness t ₂ .
t = t ₂ + (t ₁ -t ₂ ) · | cos (nθ / 2) | (where n is 1 or 2)
The thickness can be easily selected by the configuration.

  By forming the metal layer from gold, silver, copper, or aluminum, since the absolute value of the complex refractive index is large, a low-loss hollow waveguide can be obtained.

  According to the hollow waveguide application device of the present invention, when the metal pipe has a bent portion in advance, by rotating the metal pipe or the hollow waveguide, when the metal pipe does not have the bent portion in advance, the hollow guide is used. By bending the metal pipe inserted through the waveguide in a predetermined direction, the thickness distribution of the dielectric layer at the bent portion of the metal pipe changes, so the wavelength band and output intensity of light that can be transmitted during use are easily changed. It becomes possible.

  FIG. 1 shows a hollow waveguide according to a first embodiment of the present invention. In this hollow waveguide 1, a metal layer 3 is provided on the inner surface of a glass capillary tube 2 serving as a protective layer for maintaining the structure, and the layer thickness is constant in the axial direction on the inner surface of the metal layer 3, and the circumferential direction θ A different dielectric layer 4 is housed inside.

  The glass capillary tube 2 is made of, for example, quartz glass, and preferably has an inner diameter of 1 mm or less so that sufficient flexibility can be obtained. Instead of the glass capillary tube 2, a tube made of a metal such as Ni or a resin such as an epoxy resin may be used.

  As the material of the metal layer 3, gold, silver, copper, aluminum, or the like can be used. Since these have a large absolute value of the complex refractive index, a low-loss hollow waveguide can be obtained. As a method for forming the metal layer 3, a plating method, a vacuum deposition method, a sputtering method, a method of attaching a molten metal, or the like can be used.

  As a material for the dielectric layer 4, an inorganic substance or an organic resin can be used. However, it is important that the absorption is sufficiently small in the wavelength range of the light to be used. And metal oxides such as quartz, magnesium oxide, zirconium oxide, copper oxide, titanium oxide, aluminum oxide and yttrium oxide, semiconductors such as germanium and silicon, II-VI group compounds such as zinc selenide and zinc sulfide, or polyimide Polymer resins such as polycarbonate, polyethylene, polysiloxane, polysiloxane, cyclic olefin resin, fluororesin, and silicone resin can be used.

  Next, an example of a method for forming the dielectric layer 4 will be described. The dielectric layer 4 includes an “internal method” in which a dielectric layer is formed on the inner surface of the metal layer 3 formed on the inner surface of the tube 2, and an “external method” in which a dielectric layer is formed on the peripheral surface of the rod-shaped core material. Etc.]. The “internal method” and “external method” will be described below.

  The “internal method” can be formed by a liquid feeding method in which a metal layer 3 is formed inside the glass capillary tube 2 and then a dielectric solution is poured inside the metal layer 3 and then dried. . According to this liquid feeding method, the following formation procedure is generally used.

(A) Liquid feeding step: A tube having the metal layer 3 formed inside the glass capillary tube 2 is fixed vertically, and a dielectric solution is allowed to flow through the tube at a constant speed.
(B) Temporary drying step: In a state where the tube is held vertically without moving, nitrogen (or dry air, dielectric solvent, etc.) is flowed to temporarily dry the tube.
(C) Heating and drying step: The tube is moved to an electric path and heated and dried while flowing nitrogen.

  Here, in order to form the dielectric layer 4 having a film thickness distribution, a method based on its own weight and a method based on bending can be considered. In the self-weight method, the temporary drying step after the liquid feeding step is temporarily interrupted in a time shorter than that generally performed, the tube is temporarily placed again, and then the temporary drying at room temperature is resumed. When the tube is leveled in a state where the provisional drying is insufficient, the shape of the dielectric layer changes due to its own weight, and a film thickness distribution can be formed.

  In the bending method, after performing the liquid feeding step and the temporary drying step, the tube is heated and dried in a state where the tube is held at a constant bending radius. The shape of the film thickness distribution can be controlled by the size of the bending radius.

  In the “external method”, the dielectric layer 4 is formed by changing the rotational speed of a rod-shaped core material within one cycle and sputtering a target material that becomes a dielectric in synchronization with the rotation cycle of the core material. . Thereafter, the metal layer 3 is formed on the peripheral surface of the dielectric layer 4, and a tube is formed on the peripheral surface of the metal layer 3. For example, the tube can be formed by depositing Ni.

FIG. 2 shows an example of the layer thickness distribution of the dielectric layer 4. The thickness t in the circumferential direction θ of the dielectric layer 4 is expressed by the following formula (1), where t ₁ is the maximum thickness and t ₂ is the minimum thickness.
t = t ₂ + (t ₁ -t ₂ ) · | cos (θ / 2) | (1)

When light enters the hollow waveguide 1 configured as described above, the light is repeatedly reflected at the boundary between the hollow portion 5 and the dielectric layer 4 and at the boundary between the dielectric layer 4 and the metal layer 3. Propagate. Since the transmission characteristics change by selecting the layer thickness of the portion that reflects light among the maximum thickness t ₁ to the minimum thickness t ₂ of the dielectric layer 4, the wavelength band of light that can be transmitted during use, The output intensity can be changed, and the transmission loss of light transmitted during use can be changed.

FIG. 3 shows a hollow waveguide according to the second embodiment of the present invention. This hollow waveguide 1 differs from the first embodiment only in the thickness distribution of the dielectric layer 4. The thickness distribution in the circumferential direction θ of the dielectric layer 4 has two portions having a maximum thickness t ₁ and a minimum thickness t ₂ as shown in FIG.

The thickness t in the circumferential direction θ of the dielectric layer 4 is expressed by the following equation (2), where the maximum thickness is t ₁ and the minimum thickness is t ₂ .
t = t ₂ + (t ₁ -t ₂ ) · | cos (θ) | (2)
Even in such a configuration, as in the first embodiment, it is possible to form the dielectric layer 4 having a film thickness distribution, and to change the wavelength band and output intensity of light that can be transmitted. Can do.

  FIG. 4 shows a hollow waveguide application device according to the third embodiment of the present invention. In this hollow waveguide application device 10, the hollow waveguide 1 of the first embodiment is inserted into a metal pipe 11 made of aluminum, copper, stainless steel or the like having a bending portion 12 having a gentle bending radius at least at one place. It has become the composition.

  In the hollow waveguide application device 10 configured as described above, the hollow waveguide 1 having the dielectric layer 4 having a different layer thickness in the circumferential direction θ is rotated to reflect on the side 12b opposite to the inner side 12a of the bent portion 12. Since the light to be shown exhibits a reflection characteristic depending on the thickness of the dielectric layer 4, different transmission characteristics can be exhibited by turning the hollow waveguide 1. This change in transmission characteristics will be further described with reference to the drawings.

  FIG. 5 shows the transmission characteristics of the hollow waveguide 1 when the thickness of the dielectric layer 4 on the outer side 12b of the bent portion 12 is the thickest and the thinnest. In this example, when the hollow waveguide 1 is turned so that the thickness of the dielectric layer 4 located on the outer side 12b is thin, the transmission loss of the used wavelength becomes the smallest, and as the hollow waveguide 1 is turned, When the hollow waveguide 1 is rotated so that the transmission loss becomes large and the thickness of the dielectric layer 4 located on the outer side 12b becomes the largest, the transmission loss becomes the largest. It turns out that the intensity | strength of the output light from the hollow waveguide 1 can be changed by turning.

  Further, as can be seen from FIG. 5, the wavelength band in which the transmission loss is reduced can be changed as appropriate by turning the hollow waveguide 1, so that light of various wavelengths is transmitted through one hollow waveguide 1. It is also possible.

  Instead of turning the hollow waveguide 1 side, the metal pipe 11 side may be turned. When the metal pipe 11 is flexible, the metal pipe 11 may be bent after the hollow waveguide 1 is inserted into the straight metal pipe 11. Also by these, the intensity | strength and use wavelength of output light can be changed. Moreover, you may provide the bending part 12 in several places. According to this, the intensity | strength and use wavelength of output light can be changed more. Further, the thickness distribution of the dielectric layer 4 is not limited to the above embodiments, and various distributions are possible.

It is a figure which shows the hollow waveguide based on the 1st Embodiment of this invention. It is a figure which shows layer thickness distribution of the dielectric material layer of the hollow waveguide which concerns on the 1st Embodiment of this invention. It is a figure which shows the hollow waveguide based on the 2nd Embodiment of this invention. It is a figure which shows the hollow waveguide application device which concerns on the 3rd Embodiment of this invention. It is a figure which shows the loss wavelength characteristic of the hollow waveguide which concerns on the 3rd Embodiment of this invention. It is a figure which shows the conventional hollow waveguide.

DESCRIPTION OF SYMBOLS 1 Hollow waveguide 2 Glass capillary tube 3 Metal layers 4, 14 Dielectric layer 5 Hollow part 10 Hollow waveguide application device 11 Metal pipe 12 Bending part 12a Inner 12b Outer t ₁ Thickest thickness t ₂ Thinnest thickness θ circumference direction

Claims (6)

In a hollow waveguide with a metal layer inside the tube and a dielectric layer inside the metal layer,
The hollow waveguide according to claim 1, wherein the dielectric layers have different thicknesses in the circumferential direction.   The hollow waveguide according to claim 1, wherein the tube is a glass capillary tube. The thickness t in the circumferential direction θ of the dielectric layer has a maximum thickness t ₁ and a minimum thickness t ₂ .
t = t ₂ + (t ₁ -t ₂ ) · | cos (nθ / 2) | (where n is 1 or 2)
The hollow waveguide according to claim 1, wherein:   The hollow waveguide according to claim 1, wherein the metal layer is made of gold, silver, copper, or aluminum. A metal pipe having a bent portion at least in one place in advance or when used, a hollow waveguide inserted into the metal pipe, having a metal layer on the inner surface of the tube, and having a dielectric layer on the inner surface of the metal layer; In hollow waveguide application device comprising:
The hollow waveguide application device, wherein the dielectric layers of the hollow waveguide have different thicknesses in the circumferential direction.   The hollow waveguide application device according to claim 5, wherein the metal pipe and the hollow waveguide can be relatively displaced in a circumferential direction.

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