JPS60230104A - Optical fiber - Google Patents

Abstract

PURPOSE:To enable easy and exact detection of visible and UV rays by incorporating a material which exhibits a photochromism by sensing the visible or UV rays into a core and detecting the change in the optical transmission loss by the photochromism. CONSTITUTION:The quartz optical fiber 10 incorporated therein with the material 4, such as silver chloride which exhibits the photochromism by sensing visible rays and the rays shorter in wavelength than said rays into the core 1 is used. Plural times of loops are provided in the intermediate part in the longitudinal direction. If the looped part is placed near a flame F, the UV rays from the flame F transmit a transparent 2nd coating layer 5, a buffer layer 4, a primary coating layer 3 and a clad layer 2 and enter partly into the core 1 where the rays react with the silver chloride in the core and deposite silver and therefore the optical transmission loss of the fiber 10 is increased. The input to a photodetector 12 decreases and the presence of the flame F is detected. Silver reacts with chlorine and converts to silver chloride so that the fiber 10 restores the transparent state when there is no more flame.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates primarily to an optical fiber used for detecting ultraviolet rays, visible light, and the like.

[Prior art]

Conventionally, various optical energy measuring devices have been used to detect this type of light, but all of them have the drawbacks of high equipment costs, bulk, and lack of simplicity.

〔the purpose〕

The present invention was made in view of the above circumstances, and its purpose is to contain a material that exhibits a photochromic phenomenon in response to visible light or ultraviolet light in the core, and to capture changes in optical transmission loss due to the photochromic phenomenon. Accordingly, it is an object of the present invention to provide an optical fiber that allows easy and accurate detection of visible light and ultraviolet light.

〔composition〕

The optical fiber 4 according to the present invention is characterized in that the core and/or cladding layer contains a material that is sensitive to light in a predetermined wavelength range and exhibits a photochromic phenomenon.

[Example] 4 The present invention will be specifically described below based on drawings showing examples thereof. FIG. 1 is a schematic cross-sectional view of an optical fiber according to the present invention (hereinafter referred to as the product of the present invention), in which 1 is a core made of quartz, 2 is a cladding layer, and 3 is a coating such as a nylon jacket. It shows.

Inside the core 1 are visible light and light with shorter wavelengths (
A material 4 exhibiting a photochromic phenomenon in response to wavelengths (about 700 nm or less), such as silver halide, ie, silver chloride, silver bromide, silver iodide, etc., is mixed therein.

The amount of material 4 mixed into the core l is 10'' in terms of the number of crystal particles.
Approximately 102' particles/d, and the mixed particle size is 100 to 500
This is about the size of a human being, and these conditions may be set appropriately taking into consideration sensitivity and the like.

FIG. 2 is a schematic diagram showing a flame detection device constructed using the above-mentioned optical fiber according to the present invention, in which 10 indicates the optical fiber according to the present invention, 11 indicates a light source, and 12 indicates a photodetector. There is. The optical fiber 10 is composed of a quartz-based optical fiber having a core containing a material exhibiting a photochromic phenomenon, such as silver chloride, and the longitudinal middle portion thereof is looped multiple times with an appropriate size. , one end surface is connected to a reference light source 11 and the other end surface is connected to a photodetector 12, so that light from the reference light source 11 is propagated through an optical fiber 10 and detected by the photodetector 12. As the reference light source 11, a source that emits light with a wavelength of 600 na+ or more, such as an LED or an LD, is used, and this light does not cause the material 4 in the core of the optical fiber 10 to exhibit the photochroming phenomenon.

F is a gas combustion flame, and its wavelength spectral distribution is as shown in FIG. In Figure 3, the horizontal axis is the wavelength (rv
), and the level is shown on the vertical axis, and as is clear from this graph, the level of visible light sources is relatively low, but the level of ultraviolet rays is high.

Therefore, if the loop portion of the optical fiber IO as described above is placed near the flame F, the ultraviolet rays from the flame F will pass through the transparent coating 3 and the cladding layer 2 and a portion will enter the core 1. Since silver is precipitated by reacting with silver chloride in the core, the optical transmission loss of the optical fiber 10 increases and the input to the photodetector 12 decreases, so that the presence of ultraviolet rays, in other words, the flame F is detected. Become.

Of course, once the flame is gone, the silver reacts with the chlorine to form silver chloride and the fiber returns to its transparent state.

[Numerical example]

Wavelength 36 in the core of step index type quartz fiber with core diameter: 400 μm and cladding layer diameter: 500 μm.
Silver chloride, which exhibits an absorption peak for ultraviolet light of 0 nm, was
"~10'g particles/cd (particle size 100A>) were mixed, and a detection device as shown in FIG. 2 was constructed.

The reference light source is a He-Ne laser (633 nm).
was used. As a result, it was confirmed that it was possible to accurately detect ultraviolet light levels.

In both the embodiments and numerical examples described above, the material exhibiting a photochromic phenomenon is contained in the quartz-based core, but it may also be contained in the polymer core of a polymer optical fiber. Further, the mixing of the material 4 is not limited to the core; for example, the same effect can be obtained by including it in the cladding layer instead of the core, or by including it in both the core and the cladding layer. This is because light propagates not only within the core but also partially within the cladding layer within the optical fiber. Furthermore, in the above-described embodiments, the optical fibers were arranged in a coiled configuration, but it goes without saying that they may be arranged in a straight line.

〔effect〕

As described above, in the product of the present invention, a material exhibiting a photochroming phenomenon is mixed into the core and/or cladding layer, so when light in the ultraviolet region or visible region is incident on this optical fiber, the material causes a photochromic phenomenon and changes the optical transmission loss of the optical fiber, making it possible to quickly and accurately detect the presence or absence of ultraviolet rays and visible light, as well as the presence or absence of their light emitting sources, reducing equipment costs. The present invention is famous for its excellent effects, such as being inexpensive, and since the detection section is a fiber, it can be manufactured in a long length and is easy to handle.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view of the product of the present invention, Figure 2 is a schematic diagram showing an embodiment of the product of the present invention configured as an ultraviolet detection device, and Figure 3 is a schematic cross-sectional view of the product of the present invention.
The figure is a graph showing the results of spectroscopic analysis of a gas combustion flame. 1... Core 2... Clad layer 3... Covering part 1
0...Optical fiber 11...Light source 12...Photodetector F...Flame patent Applicant Dainichi Nippon Cable Co., Ltd. Agent Patent attorney Noboru Kono - Strand 1 eye 10 26G 444 ω8 772 q36 r Io. N Liang Fu (ηm) Figure 3 Procedural amendment (voluntary) May 31, 1980 Ko 1 Title of invention Optical fiber 3, Relationship with the person making the amendment case Patent applicant da 0 agent] j, Amendment → (1) On page 2, line 18 of the specification, Kr3 is a covering part such as a nylon jacket. ``Layer'' is corrected. (2) On page 3, line 1 and line 4 of the specification, “Material 4
” are respectively corrected as “Material 6.” (3) "Material 4" on page 4, line 1 of the specification,
Correct it to "Material 6." (4) On page 4, line 10 of the specification, the phrase "transparent coating portion 3" is corrected to read "transparent secondary coating layer 5, buffer layer 4, secondary coating layer 3, and". (6) On page 5, line 10 of the specification, the VC "Material 4" is corrected to "Material 6." 6-2 In the 15th line of page 6 of the specification in the "Brief explanation of the drawings" section, the phrase "3...coating part" has been replaced with "3...-second coating layer, 4... buffer layer". , 5...secondary coating layer, 6...photochromic material". 6-3 9 corrections have been made to Figures 1 and 3 in the attached sheet. 2. Catalog of attached documents (凰) Correction drawing 1 copy Figure 1 5 Tomonaga (n town Figure 3

Claims (1)

[Claims] 1. An optical fiber characterized in that a material exhibiting a photochromic phenomenon in response to light in a predetermined wavelength range is mixed into the core and/or cladding layer. 2. The optical fiber according to claim 1, wherein the wavelength range is a visible and ultraviolet range. 3. The optical fiber according to claim 1, wherein the material is silver chloride, tin bromide, or silver iodide.