JPS58117477A - Radiation detector - Google Patents

Abstract

PURPOSE:To achieve an automatic measurement at a remote point with a high reliability by connecting a luminous material integral to the tip of an optical fiber. CONSTITUTION:A luminous material 22 is provided integral at the tip of an optical fiber 22. The tip of the optical fiber 21 is covered with a reflecting film coating 24 such as aluminumdeposited film or the like so that light from the luminous material 22 can be coupled to the optical fiber 21 so effectively as to achieve a higher efficiency of detecting radiation. When the luminous material 22 is sealed into the tip of the optical fiber 21 by removing not only core but also cladding, the sensitive area can be increased with respect to radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) This invention uses a radiation system aK@ that combines a light-emitting substance and an optical fiber.

(Prior art and its problems and requirements) FIG. 1 shows the prior art that is closely related to this invention.

In the figure, l is luminescent material (radiation thermal fluorescent material (LiF:Mg
etc.) or phosphate glass [lambda = 365 nm ultraviolet excitation causes orange color (λ2 = 500-700 fi
Emits @ fluorescent light. ), ), 2 is a photodetector, 3 is an amplifier, 4 is a power source, 5 is a heat source or light source, and 6 is a dose indicator. The operating principle is based on the fact that a luminescent area is obtained that is proportional to the amount of radiation irradiated to the luminescent material.
The luminescent material can be used either by putting it into a measurement system as shown in the figure, or by irradiating it with radiation alone and then putting it into the measurement system.

However, KlIJ51# [The following points can be raised.

When a +11 luminescent substance is irradiated alone, it is difficult to take it in and out of the measurement system, making it unsuitable for automatic measurement of one remote point.

(2) Even when using the measurement system while it is still inside, there is a possibility that the heat source, light source, or photodetector may be exposed to radiation.
There are problems with reliability.

(Object of the Invention) An object of the present invention is to provide a highly reliable radiation detector that is capable of automatically measuring the radiation dose at a remote point.

(Summary of the Invention) By integrally bonding a luminescent substance to the tip of an optical fiber, automatic measurement at a remote point can be performed with high compensation.

(Example of the invention) In Figure 2, which shows an example of the invention, 7 is a luminescent substance (
8 is an optical fiber (81: core part, 82: cladding part, 83: coating part), 9 is a light source (cO2 for thermal fluorescer)
laser or YAG laser, while for phosphate glass, the emission spectrum includes λ1 = 3651 m), 10 is a photodetector, 11#i amplification S%, 12 is a half mirror, and 113 is a dose indicator, respectively. show. As is clear from this figure, K.

Optical fibers serve two purposes: heating or photoexciting luminescent substances and transmitting light by emitting light.

(Effect of the invention) According to the present invention, the following effects can be obtained.

(1) Automatic measurement of radiation dose at remote points becomes possible.

(2) Reliability is improved because the light source and heat 11% photodetector are not irradiated with radiation.

(3) Since the signal transmission medium is an optical fiber, it has excellent features such as resistance to brazing and magnetic induction.

(Example of Pond of Invention) This invention is not limited to the above embodiments.

Another embodiment is shown in FIGS. 3 to 8. In FIG. 3, the tip of the optical fiber 21 is covered with a reflective film coating 24 such as akinium evaporated@, and thereby the luminescent material 22
By coupling the light from the source to the optical fiber 21 in a smooth manner, radiation detection efficiency can be increased. In FIG. 4, not only the core but also the cladding of the tip of the optical fiber 21 is removed and a luminescent material 22 is encapsulated, thereby increasing the area sensitive to radiation. FIG. 5 is a modification of FIG. 3, in which a tip reflector 25 such as a metal cap is attached to the tip, and as in FIG. 3, the radiation detection efficiency is increased. In FIG. 6, not only the core but also the cladding is removed from the tip of the optical fiber 21, and a luminescent material 22 coated with a coating 26 of 11 degrees equal to the cladding thickness is buried here. Core 211. The refractive index of the cladding 212 is nl and n2, respectively, and the refractive index of the luminescent material 22 and coating 26 is "@e", respectively.
By adding t to /#I to K, the light from the light-emitting substance 22 can be efficiently coupled to the optical fiber 21.

FIG. 7 shows a method in which a manching material 27 such as silicone oil, polyurethane resin, or polystyrene is inserted between the luminescent substance 22 and the core 21 to further strengthen the light supply. FIG. 8 shows a configuration using a converging type deformed optical fiber 21 with a diameter of 9. If this structure is used, it becomes easy to embed the luminescent substance 22 in the tip. These Figure 3~
The embodiment shown in FIG. 8 can be combined and applied as appropriate.

In the above embodiments, all step-index optical fibers are used, but the present invention can be similarly practiced using graded-index optical fibers.

As described above, according to the present invention, the luminescent material and the original fiber are directly and integrally coupled.

It is possible to provide a radiation detector that is small in size, has high detection efficiency, and is useful when applied to a one-dimensional or two-dimensional radiation @amount distribution measuring device as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional example, FIG. t42 is a diagram showing an embodiment of the present invention, and FIGS. 3 to 9 are diagrams showing other embodiments and application examples of the present invention. 7... Luminescent substance, 8... Optical fiber, 9... Light source, 10... Photodetector, 11... Amplifier, 12...
Half mirror 113...dose indicator. Figure 1 Figure 3 Figure 21 Figure 5 21 ??

Claims (2)

[Claims] (1) A substance that emits light by heating or irradiating it with light after being irradiated with radiation is attached to the tip of the optical fiber.
A radiation detector characterized by comprising: (2) The radiation detector according to claim 1, wherein the light-emitting substance is embedded in nine locations by partially removing the IC from a component at the tip of the optical fiber.