JPS60230105A - Optical fiber - Google Patents

Abstract

PURPOSE:To enable exact conversion and detection of the quantity of the UV rays in the light propagated into an optical fiber in the form of quantity of fluorescence by incorporating a fluorescent material which emits fluoresence by sensing the light of a prescribed wavelength region into at least one layer of the multi-layered structure of the optical fiber. CONSTITUTION:The optical fiber 10 consists of a core 1 made of quartz and a clad layer 2 made of a polymer. About 1,000ppm fluorescent material is incorporated into the layer 2. The top ene and intermediate part are looped plural times and the other end face is connected to a photodetector 11. If the looped part is placed to face a flame F, the light of the flame F is made incident on the inside of the fiber 10 from one end face or the peripheral surface in the intermediate part of the fiber 10 and since part thereof passes the inside of the layer 2, the UV rays included therein are absorbed into the fluorescent material 4 and fluorescence is emitted from the material 4. The fluorescence enters not only the clad layer 2 but also the inside of the core 1, propagates in the core and is captured by a photodetector 11, by which the energy thereof is detected and the flame is thus detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention mainly relates to an optical fiber used for detecting ultraviolet light.

[Prior art]

Conventionally, ultraviolet rays have been detected using spectroscopic analyzers, etc., but this has the disadvantage of high equipment costs for use in flame detection, etc.

〔the purpose〕

The present invention has been made in view of the above circumstances, and its purpose is to make at least one layer of the core, cladding layer, or buffer layer surrounding them of an optical fiber emit fluorescence in response to ultraviolet light. An object of the present invention is to provide an optical fiber in which the amount of ultraviolet rays in propagated light can be accurately converted and detected as the amount of fluorescence by containing a fluorescent substance.

〔composition〕

The optical fiber according to the present invention is characterized in that at least one layer of the multilayer structure contains a fluorescent material that emits fluorescence in response to light in a predetermined wavelength range.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention and its embodiments will be explained in detail below based on the drawings. 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 quartz-based core, 2 is a polymer cladding layer, and 3 is a material that transmits ultraviolet rays. This shows the covering part made up of the following. Note that the covering portion 3 may be omitted.

In the cladding layer 2, there is a fluorescent substance 4 of 10 to 50 + 00 that emits fluorescence in response to ultraviolet light (100 to 400 nm).
Approximately 0 ppm, preferably ioo to 30,000 ppm
It is recommended to contain it to some extent. If it is less than 10 ppm, sufficient fluorescence cannot be obtained, and even if it exceeds 50,000 ppm, the amount of fluorescence hardly changes, which increases the cost of the optical fiber.

As the fluorescent substance 4, M g W O4, ([3a Ca
Mg)(PO4)3:ELl,(SrMg
) 3 (PO4):Su, Y202S:Eu
SY (P, V)0<: Eu, Zn S: Cu
, Al, Zn S-: Cu, Au, A6°Nd20i
There are many organic substances such as rhodamines (for example, Excitonnese trade name Rhodamine 590) and oxazines. These fluorescent substances can be used alone or in combination.

All of these fluorescent substances 4 absorb ultraviolet rays and emit visible light of 500 to 800 nm or infrared light of 800 to 2 nm.
,000 nm, and by the way, (
Regarding Sr Mg )3 (PO4)2 :Su, its emission spectrum is as shown in FIG.

FIG. 2 shows the wavelength (r+m) on the horizontal axis and the emission energy on the vertical axis, and as is clear from this graph, the emission energy is especially high in the visible range of 550 to 700 nm.

Regarding the method of mixing the fluorescent substance into the cladding layer 2 as described above, for example, the fluorescent substance is added to a polymer that is liquid at room temperature, stirred by an appropriate means, and the fluorescent substance is temporarily dispersed. The cladding is formed by coating and baking.

In addition, although the above-mentioned embodiment explained the configuration in which the fluorescent substance 4 is mixed in the polymer cladding layer, the fluorescent substance 4 may be mixed in the quartz core and/or the polymer cladding layer. The core and cladding layers themselves may be made of any conventionally known materials such as quartz, pomer, etc.

FIG. 3 is a schematic diagram showing a detection device for ultraviolet rays emitted from a gas combustion flame, which is constructed using the above-mentioned optical fiber of the present invention, and in the figure, numeral 10 indicates the optical fiber of the present invention;
11 indicates a photodetector.

The optical fiber 10 has a core made of quartz and a cladding layer made of polymer, and the cladding layer contains about 11,000 pp of fluorescent material.The tip and middle portions are looped multiple times, and the other end surface is made of light for detection. It is connected to the device 11. Note that the one end surface may be arranged to face the flame F.

The light from the flame F enters the optical fiber 10 from the end surface or the circumferential surface of the intermediate portion of the optical fiber 10, and a part of it passes through the cladding layer 2, so that the ultraviolet light contained in the light from the flame F is absorbed by the fluorescent substance 4, and the fluorescent substance 4 emits fluorescence. The fluorescence not only enters the cladding layer 2 but also partially enters the core 1 and propagates through the core, is captured by the photodetector J2, and its optical energy is detected. As a result, the presence or absence of ultraviolet rays, in other words, the presence or absence of the flame itself can be detected, and the length, size, etc. of the flame can be measured.

Furthermore, in the optical fiber in which a so-called buffer layer is provided between the cladding N2 and the covering portion 3 shown in FIG. 1, it goes without saying that a fluorescent material may be mixed into this buffer layer.

〔effect〕

As described above, in the present invention, since the fluorescent material is mixed into at least one layer of the multilayer structure, when ultraviolet light is present in the light incident on the optical fiber, the fluorescent material in the optical fiber emits fluorescence, This fluorescence is propagated inside the core, and by detecting the energy level of this fluorescence, the energy level of the ultraviolet rays in the incident light can be easily and accurately detected, making it possible to detect ultraviolet rays accurately with simple equipment. The present invention has excellent effects such as being able to perform the following.

[Brief Description of the Drawings] Figure 1 is a schematic cross-sectional view of the product of the present invention, Figure 2 is a graph showing the spectral distribution of the emitted light from the fluorescent substance, and Figure 3 is a graph showing the spectral distribution of the emitted light from the fluorescent substance.
The figure is a schematic diagram showing an embodiment of an ultraviolet detection device constructed using the product of the present invention. 1... Core 2... Clad layer 4... Fluorescent material 10... Optical fiber 11... Photodetector F...
At the time of the flame Applicant Dainichi Nippon Electric Cable Co., Ltd. Agent Patent attorney Noboru Kono Liquid roast (nm) Grass 2 Button calculation 3 Draft procedure amendment (voluntary) May 31, 1980 Commissioner of the Japan Patent Office Tono case and Relationship between Patent Applicant G8 Agent J, 1. Detailed Description of the Invention in the Specification Subject to Amendment and Drawing G, Contents of Amendment 6-1 5. On the 11th line of the page, the phrase ``Also, as shown in Figure 1'' in IC is corrected to ``Also, as in Figure 1, like the silica-based optical fiber.'' Gloss IP 2 figure

Claims (1)

[Claims] 1. An optical fiber characterized in that at least one layer of a multilayer structure contains a fluorescent substance that emits fluorescence in response to light in a predetermined wavelength range.