JPH09145940A - Fiber optical plate and radiation image detector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber optical plate which is capable of sufficiently prohibiting the transmission of radiation and can be easily and stably produced even if a high numerical aperture(NA) is attained by making the refractive index difference between core and clad relatively large. SOLUTION: This fiber optical plate has the plural cores 100 consisting of a core glass material for propagating incident light and the clad 101 consisting of a clad glass material for covering the outer peripheral parts of the respective cores 100 and packing the spacings among the adjacent cores. The core glass material and clad glass material contain lead oxide and the content of lead oxide in the core glass material is higher than the content of lead oxide in the clad glass material. In addition, the clad glass material contains 0.3 to 3.0wt.% lithium oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber optical plate having a plurality of cores and a clad covering the outer peripheral portion of each core and filling a space between adjacent cores, and a radiation image detecting apparatus using the fiber optical plate.

[0002]

2. Description of the Related Art Conventionally, as a fiber optic plate used in a radiation image detecting device, one using a glass for blocking radiation is known as a core, and such a fiber optic plate is disclosed in, for example, JP-A-63-311193. It is described in Japanese Patent Application Laid-Open No. 1-227583.
In the fiber optic plate described in the above publication, the light transmission axis C of the fiber optic plate is curved (FIG. 9) or the fiber to prevent radiation from entering the image sensor through the cladding. The optical transmission axis C of the optical plate was designed to intersect the radiation incident direction D at a predetermined angle (FIG. 10). 9 and 10, 1 is a fiber optical plate, 2 is a fluorescent film, and 3 is an image sensor.

[0003]

However, even when the above-mentioned conventional fiber optic plate is used, the prevention of the incidence of radiation on the image pickup element is not always sufficient. Also, when the light transmission axis is curved or inclined like these fiber optical plates, the end face of each fiber is not perpendicular to its longitudinal axis, so the light receiving and emitting angles become small, and the light (“radiation There is a limit to the improvement of the transmittance of "long wavelength light": the same applies hereinafter. Furthermore, in order to manufacture the above-mentioned conventional fiber optic plate, a relatively difficult additional step such as bending the light transmission axis is required, sufficient prevention of optical defect occurrence, and improvement in yield,
There was a limit to the reduction of manufacturing cost.

Therefore, an object of the present invention is to achieve a high numerical aperture (NA) by being able to sufficiently block the transmission of radiation, and further by making the refractive index difference between the core and the clad relatively large. Even in this case, it is to provide a fiber optic plate that can be manufactured easily and stably without inconvenience such as occurrence of optical defects.

Another object of the present invention is to sufficiently prevent the transmission of radiation to the image pickup device while maintaining the transmission efficiency of the light emitted from the scintillator to the image pickup device at a high level. Another object of the present invention is to provide a radiation image detecting device which has a high resolution and a high S / N ratio, has a long life, and is easy to manufacture.

[0006]

A fiber optic plate according to the present invention includes a plurality of cores made of a core glass material for propagating incident light and a core which covers an outer peripheral portion of each core and is adjacent to each other. A fiber optic plate having a clad made of a clad glass material, wherein the core glass material and the clad glass material contain lead oxide, and the lead oxide content in the core glass material is A fiber optic plate having a lead oxide content higher than that of the clad glass material, and the clad glass material containing 0.3 to 3.0% by weight of lithium oxide.

The fiber optical plate of the present invention (hereinafter,
In (FOP), since lead oxide is present in both the core and the clad, not only the radiation incident on the core but also the radiation incident on the cladding is sufficiently absorbed in the FOP. Furthermore, since the lead oxide content in the core glass material is higher than the lead oxide content in the clad glass material, the refractive index of the core glass material becomes larger than that of the clad glass material, and the incident light enters the core. The generated light efficiently propagates in the core. In the FOP of the present invention, the content of lead oxide that lowers the yield point is set higher in the core glass material than in the clad glass material, but the clad glass material contains the above predetermined amount of lithium oxide. Since the material is added, the difference between the sag points of both materials becomes small, and it is possible to sufficiently prevent the core glass material from becoming droplets when drawing (drawing) and connecting the adjacent core parts during hot pressing. Thus, the FOP of the present invention can be easily and stably manufactured.

Further, the radiation image detecting apparatus of the present invention comprises (i) a plurality of cores made of a core glass material for propagating incident light, and a core which covers an outer peripheral portion of each core and is adjacent to each other. A fiber optic plate having a clad made of a clad glass material filled with
The core glass material and the clad glass material contain lead oxide, the lead oxide content in the core glass material is higher than the lead oxide content in the clad glass material, and the clad glass material is lithium. 0.3 ~ oxide
A fiber optic plate containing 3.0% by weight; (ii) a scintillator optically connected to one end of the fiber optic plate; (iii) imaging optically connected to the other end of the fiber optic plate And a radiation image detecting device including;

Since the radiation image detecting apparatus of the present invention uses the above-described FOP of the present invention, the transmission efficiency of light (radiation image) from the scintillator to the image pickup element is maintained at a high level and the image pickup element is sent to the image pickup element. Of the radiation X is sufficiently blocked, and damage to the image sensor due to the transmitted radiation is prevented.
Further, since the transmission efficiency is maintained at a high level and the noise caused by the transmitted radiation is reduced, the resolution and the S / N ratio are improved. Furthermore, since the FOP of the present invention can be manufactured easily and stably as described above, the manufacture of the radiation image detecting device of the present invention becomes easy.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. The same or corresponding parts will be denoted by the same reference numerals.

First, the fiber optical plate of the present invention will be described. FIG. 1 shows a perspective view of an example of the fiber optical plate (hereinafter referred to as FOP) of the present invention. This FOP1 is a multi-multi fiber (MMF) described later.
As shown in FIG. 2, the multi-multi fiber 10 comprises a core 100 and a clad 101 that covers the outer periphery of the core 100 as shown in FIG.
Single fiber consisting of and (optical fiber: SF)
A plurality of multi-fibers (MF) 120 obtained by aligning and fusing a plurality of 110 are further aligned and fused. Therefore, as shown in a partial cross section of FIG. 2, the FOP 1 includes a large number of cores 100 arranged in parallel with each other, and a clad 101 that covers the outer peripheral portion of each core 100 and fills the space between adjacent cores 100. It consists of and.

In the FOP of the present invention, both the core glass material forming the core 100 and the clad glass material forming the clad 101 contain lead oxide, and the lead oxide in the core glass material is contained. The content must be higher than the content of lead oxide in the clad glass material.

As described above, the core 100 and the clad 101 are
By including lead oxide in both
As shown in FIG. 3, not only the radiation X ′ that has entered the core 100 but also the radiation X ″ that has entered the clad 101 is sufficiently absorbed in the FOP 1. Therefore, in the FOP of the present invention, the transmission of the radiation X (X ′ and X ″: the same applies hereinafter) is sufficiently blocked without bending the light transmission axis B. And
When the FOP of the present invention is used in the radiation image detecting apparatus described later, the FOP1
There is no possibility that the image pickup device connected to is damaged or generates noise.

When the content of lead oxide in the glass material is increased, the refractive index (nd) is improved as shown in FIG. Therefore, by making the lead oxide content in the core glass material higher than the lead oxide content in the cladding glass material, the refractive index of the core glass material becomes larger than that of the cladding glass material. Therefore, in the FOP of the present invention, the core 100 constitutes an optical waveguide and the incident light F
Propagate in the core 100. The composition other than lead oxide of the glass material shown in FIG. 4 and FIGS. 5 and 6 described later is as shown below.

Glass composition (% by weight) SiO ₂ 18.9 to 57.6 Al ₂ O _{3 0 to} 0.8 K ₂ O 0.3 to 9 PbO 27 to 80 Core glass material and clad glass material according to the present invention The content of lead oxide in each is 54 to 85% by weight and 27, respectively.
Is preferably 75 to 75% by weight, and 75 to 8%, respectively.
Especially preferred are 5% by weight and 27-55% by weight. As shown in FIG. 5, when the lead oxide content in the glass material is high, the radiation absorption rate is improved. Therefore, if the lead oxide content is in the above range, the radiation transmission tends to be blocked more reliably. Because there is. Particularly, when the content of lead oxide in the clad glass material is 27% by weight or more, the radiation transmittance of not only the core 100 but also the clad 101 is 10% or less in the FOP having a thickness of 3 mm (see FIG. 5). preferable.

The difference between the lead oxide content in the core glass material and the lead oxide content in the clad glass material is 10
It is preferably at least wt%, particularly preferably at least 27 wt%. This is because the numerical aperture (NA) increases and the light transmission efficiency tends to increase by increasing the difference in the lead oxide content between the core and the clad to increase the difference in the refractive index. In particular, when the FOP of the present invention is used in a radiation image detecting device described later, it is preferable that the numerical aperture is large. That is, since the scintillator 2 connected to the FOP 1 emits light in all directions, a large numerical aperture, that is, a large light receiving angle is required to propagate the light efficiently. The numerical aperture (NA) is the refractive index (N
_It is determined by the difference between ₁ ) and the refractive index (N ₂ ) of the clad glass material, and is defined by the following equation (1).

NA = {(N ₁ ) ² − (N ₂ ) ² } ^1/2 (1) Then, when the numerical aperture is 1.0 or more, the incident angle is about 90 ° with respect to the light transmission axis B of the FOP 1. In theory, even such light can propagate, and a very high level of transmission efficiency can be achieved. Therefore, in the FOP of the present invention, the numerical aperture is 1.0
The difference is preferably 0.28 or more between the core glass material and the clad glass material.

In the FOP of the present invention, the cladding 10
It is necessary that the clad glass material constituting No. 1 further contains lithium oxide in an amount of 0.3 to 3.0% by weight, preferably 0.3 to 1.5% by weight, in addition to the lead oxide. In the present invention, the addition of a predetermined amount of lithium oxide to the clad glass material is essential for the stable production of the FOP of the present invention easily and without inconvenience such as occurrence of optical defects. It is possible to manufacture even an FOP in which a large amount of lead oxide is added to each of them and the refractive index difference between the core and the clad is relatively large to achieve a high numerical aperture (NA). Hereinafter, the reason will be described in more detail.

As the content of lead oxide in the glass material increases, the yield point (softening temperature: At) and transition point (Tg) decrease as shown in FIG. Therefore, if the lead oxide content in the core glass material is higher than the lead oxide content in the clad glass material as described above, the difference between the sag points of both materials becomes large. That is, for example, the refractive index of the core glass material is 1.92, and the refractive index of the clad glass material is 1.5.
Considering the case of 6, the difference in lead oxide content is about 53.
% By weight (see FIG. 4) and the difference in yield point is about 85 ° C. (see FIG. 6). In this way, a pipe made of a combination of a core glass material and a clad glass material having a large difference in deformation point is used.
When the wire drawing is carried out by the rod method or the like, at that time, only the core glass material is remarkably softened, and it becomes easy to drop into droplets, so that the wire drawing becomes very difficult. Further, if the difference in yield point is large, the clad portion is cut off when the plurality of drawn fibers are fused and integrated by hot pressing or the like,
Since the core portion flows out and becomes easy to communicate with the adjacent core portion, an optical defect will occur.

On the other hand, when lithium oxide is added to the clad glass material, as shown in Table 1 and FIG.
The yield point and transition point of the glass material containing lead oxide are significantly reduced.

[0021]

[Table 1]

Therefore, even when the lead oxide content in the core glass material is higher than the lead oxide content in the clad glass material, the above-mentioned predetermined amount of lithium oxide should be added to the clad glass material. This makes it possible to reduce the difference between the sag points of both materials, preferably within 50 ° C., particularly preferably within 30 ° C., and to make the core glass material into droplets at the time of drawing a wire and adjoining at the time of hot pressing. Communication of the core portion is sufficiently prevented. Therefore, particularly, both the core and the clad contain a large amount of lead oxide, and the difference in the lead oxide content between the core glass material and the clad glass material is 27% by weight or more to achieve a high numerical aperture (NA). Even the above FOP can be easily and stably manufactured by adding a predetermined amount of lithium oxide to the clad glass material.

That is, for example, the following characteristics are obtained when the refractive index of the core glass material is 1.9 or more: Radiation transmittance in the clad: FOP having a thickness of 3 mm
In order to achieve a numerical aperture (NA) of 1 or more, it is necessary that the content of lead oxide in the clad glass material is 27% by weight or more and the refractive index is 1.615 or less. Therefore, if the prescribed amount of lithium oxide is not added to the clad glass material, the yield point difference is 5
If the temperature exceeds 0 ° C., line drawing becomes extremely difficult and optical defects occur. On the other hand, in the present invention, when the above-mentioned predetermined amount of lithium oxide is added to the clad glass material, it becomes possible to reduce the difference between the sag points of both materials to within 30 ° C., whereby the above-mentioned various characteristics are simultaneously achieved. Even the achieved FOP can be manufactured easily and stably.

Although the lithium oxide lowers the yield point of the glass material as described above, since the molecular weight is small and the influence on the refractive index is very small, addition of the lithium oxide to the cladding causes a difference in the refractive index. No reduction in numerical aperture is brought about. However, the content of lithium oxide is 0.3
If it is less than wt%, the yield point is not sufficiently lowered, while if it exceeds 3.0 wt%, the coefficient of thermal expansion becomes large.
The tensile stress is applied to the clad, which reduces the mechanical strength of the fiber.

By the way, the base glass is changed to SiO ₂ -Pb.
It was confirmed that when O—R ₂ O (R = Na, K) and which component was replaced with 1% by weight of Li ₂ O, the yield point of the glass was further lowered, SiO ₂ >PbO> K ₂
The yield point was greatly lowered in the order of O> Na ₂ O. Therefore, in the glass materials (b, c) shown in Table 1, SiO
₂ is replaced with Li ₂ O.

As shown in FIG. 2, the FOP of the present invention has the optical absorber 1 in addition to the core 100 and the clad 101 described above.
It is preferable to further include 02. The light absorber 102 is
As shown in FIG. 3, it is for absorbing the light F ′ leaked from the core 100 and the light F ″ incident on the clad 101, and includes manganese oxide, chromium oxide, iron oxide, cobalt oxide. It is made of a light absorbing glass material containing at least one selected from the above, preferably 5 to 30% by weight. When the light absorber 102 is provided, the light F ′ leaked from the core 100 and the light F ″ incident on the clad 101 are absorbed, so that the S / N ratio of the transmitted image tends to be improved.
When the light absorber 102 is arranged in parallel with the core 100 as shown in FIG. 3, the radiation X ′ ″ incident on the light absorber 102 is also absorbed in the light absorber 102 and sufficiently blocked. Therefore, the light absorber 102 is also made of lead oxide 27.
It is preferable that the content is up to 85% by weight.

Next, the radiation image detecting apparatus of the present invention will be described.

The radiation image detecting apparatus of the present invention is provided with the FOP 1 of the present invention as shown in FIG. 8 as an example, and the scintillator 2 optically connected to one end of the FOP 1 and the FOP 1 are provided. The solid-state image sensor 3 optically connected to the other end is further provided. The scintillator 2 emits light in response to irradiation of the radiation X such as X-rays emitted from the radiation source 4, and it is possible to use a fluorescent film such as zinc sulfide as the scintillator 2. In addition, the image sensor 3
Is a device that converts the spatial distribution of the emitted light into an electric signal or the like (for example, a video signal) in a form that can be displayed as an image, and various image pickup elements can be adopted.

In the radiation image detecting device shown in FIG.
Light is emitted from the scintillator 2 in accordance with the radiation X emitted from the radiation source 4, transmitted through the sample 5, and applied to the scintillator 2, and the light is incident on the FOP 1 as a radiation image and propagated to the image sensor 3. . Then, the spatial distribution of the light is converted into an electric signal in the image pickup device 3, amplified by the amplifier 6, and then input to the computer 7, recorded in a recording medium (floppy disk or the like) and subjected to various image processing. Then, the information (radiation image) of the sample 5 is displayed as an image on the display 8.

At this time, in the radiation image detecting apparatus of the present invention, the transmission efficiency of light (radiation image) from the scintillator 2 to the image pickup device 3 is maintained at a high level by the FOP 1 of the present invention as described above. The transmission of the radiation X to the image sensor 3 is sufficiently blocked. Therefore, in the radiation image detecting apparatus of the present invention, the imaging element 3 is not damaged by the radiation that has passed through the FOP 1, so that a long life is achieved. Further, since the transmission efficiency is maintained at a high level and no noise is generated due to the radiation transmitted through the FOP 1, the resolution and S / N ratio of the radiation image detecting apparatus of the present invention are reduced.
The ratio is improved over the past. Further, the FOP1 of the present invention is
As described above, even when lead oxide is contained in both the core and the clad and a high numerical aperture (NA) is achieved, stable production can be performed easily and without inconvenience such as occurrence of optical defects. Therefore, the radiation image detecting device of the present invention can be easily manufactured.

[0031]

EXAMPLES Examples of the present invention will be described in more detail below.

Example 1 Using the core glass material, clad glass material and light absorbing glass material shown in Table 2, the FOP of the present invention was prepared by the following method.
1 was produced.

[0033]

[Table 2]

First, in a tube of clad glass material having the composition shown in Table 2 (outer diameter 36.7 mm, wall thickness 2.45 mm, length 800 mm), a rod of core glass material having the composition shown in Table 2 (outer diameter 30.0 mm) was used. , Length of 550 mm), and in that state both materials are softened in an electric furnace (furnace temperature: 600 ° C.) and drawn by vacuum evacuation to obtain a single fiber (SF) with a diameter of 4-5 mm. It was Further, a light absorber fiber (length: 1100 mm) having a diameter of 4 to 5 mm was obtained in the same manner except that the light absorbing glass material having the composition shown in Table 2 was used instead of the core glass material.

Next, 58 single fibers (S
F) and three light absorber fibers are aligned in a hexagonal shape with five fibers on one side as shown in FIG. 2, and again drawn under the same conditions as described above to obtain the multi-fiber shown in FIG. Fiber (MF) 120 was obtained. The three light absorber fibers were finally arranged so as to be even.

Further, multi-fiber (MF) 120
Was aligned in a hexagon having 12 multifibers on one side, and again drawn under the same conditions as above to obtain a multimultifiber (MMF) 10. The distance between opposite sides of the multi-multi fiber (MMF) 10 thus obtained was 0.9 mm, and the diameter of each single fiber (SF) constituting the same was about 6 μm.

After that, multi-multi fiber (MM
F) 10 was cut into a certain length, aligned in a mold, and hot pressed under the same conditions as above to obtain a fiber block. After cooling the fiber block, sliced perpendicular to the longitudinal direction of the fiber, polished,
FOP1 (thickness 3 mm) shown in FIG. 1 was obtained.

The yield points and transition points of the core glass material and the clad glass material used in this example are shown in Table 2, and the core glass material did not turn into droplets during drawing, and hot pressing At that time, the adjacent core portions did not communicate with each other. Further, the thermal expansion coefficients of both materials were as shown in Table 2, but they did not adversely affect the obtained FOP such as reduction of mechanical strength. Therefore, in this example, an FOP having the following characteristics could be easily and stably produced, and the obtained FOP had very few optical defects and was of very good quality.

The X-ray transmittance and the refractive index of the core glass material and the clad glass material used in this example are shown in Table 2, and the obtained FOP had the following characteristics.

(Characteristics of FOP) ・ NA: 1.12 (calculated value) ・ Fiber size: 6 μm or less (distance between fiber centers) ・ X-ray transmittance: 0.25% ・ Resolution (ln / p): 90 .6 (according to USAF1951 test target) The X-ray transmittance in Table 2 and above is 70 KVp,
It is the X-ray transmittance in the case of an FOP having a thickness (t) of 3 mm under the condition of 1.5 mA.

As described above, the FOP obtained in this example has an extremely low X-ray transmittance and a high numerical aperture, so that it has a very high light transmission efficiency and a high level of resolution. Moreover, it was possible to manufacture easily and stably.

Next, the radiation image detecting apparatus of the present invention shown in FIG. 8 was prepared by using the above FOP1. The scintillator 2 is P-43, and the solid-state image sensor 3 is CCD.
It was used.

In the obtained radiation image detecting device, F
The imaging element 3 was not damaged by the radiation transmitted through OP1, and had a long life. In addition, the obtained radiation image detecting device had a high light transmission efficiency in the FOP 1, was free from noise caused by the radiation transmitted through the FOP 1, and had a high level of resolution and S / N ratio.

Example 2 FOP1 of the present invention was produced in the same manner as in Example 1 except that the PbO content in the core glass material and the clad glass material was changed as follows.

(PbO content) -Core glass material: 75% by weight-Clad glass material: 27% by weight The difference between the yield points of the core glass material and the clad glass material used in this example was 8 ° C. Similar to item 1, the FOP of this example had very few optical defects and was of very high quality, and could be easily and stably manufactured.

The core glass material and the clad glass material used in this example have a refractive index of 1.
85 and 1.56, the obtained FOP had an extremely low X-ray transmittance as in Example 1, and had a high numerical aperture (NA = 1).
Therefore, the optical transmission efficiency is very high, the resolution is high, and the manufacturing is easy and stable.

Example 3 FOP1 of the present invention was produced in the same manner as in Example 1 except that the PbO content in the core glass material and the clad glass material was changed as follows.

(PbO content) -Core glass material: 82% by weight-Clad glass material: 55% by weight The difference between the yield points of the core glass material and the clad glass material used in this example was 5 ° C. Similar to item 1, the FOP of this example had very few optical defects and was of very high quality, and could be easily and stably manufactured.

The core glass material and the clad glass material used in this example have a refractive index of 1.
95 and 1.674, and the FOP obtained is from Example 1.
The X-ray transmittance is extremely low, and the high numerical aperture (NA =
Since it has 1), it has a very high light transmission efficiency, has a high level of resolution, and can be manufactured easily and stably.

[0050]

As described above, according to the fiber optic plate of the present invention, it is possible to sufficiently prevent the transmission of radiation, and also to make the refractive index difference between the core and the clad relatively large and to increase the refractive index. Even when the numerical aperture (NA) is achieved, it is possible to easily and stably manufacture without inconvenience such as occurrence of optical defects.

Further, according to the radiation image detecting apparatus of the present invention using the fiber optical plate of the present invention, the transmission efficiency of light from the scintillator to the image pickup element is maintained at a high level while the transmission of radiation to the image pickup element is maintained. It is possible to prevent the radiation image sufficiently, the resolution and the S / N ratio are improved, the life is extended, and the radiation image detecting device is easily manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a fiber optical plate of the present invention.

FIG. 2 is a cross-sectional view of a part (multifiber) of an example of the fiber optical plate of the present invention.

FIG. 3 is a vertical cross-sectional view of a part (cross section AA) of the fiber optical plate of the present invention shown in FIG.

FIG. 4 is a graph showing an example of the relationship between the PbO content and the refractive index.

FIG. 5 is a graph showing an example of the relationship between PbO content and radiation transmittance.

FIG. 6 is a graph showing an example of the relationship between the PbO content and the yield point and transition point.

FIG. 7 is a graph showing an example of the relationship between the Li ₂ O content and the SiO ₂ content and the yield point and the transition point.

FIG. 8 is a schematic view showing an example of a radiation image detecting device of the present invention.

FIG. 9 is a vertical sectional view schematically showing an example of a conventional fiber optical plate.

FIG. 10 is a vertical sectional view schematically showing another example of a conventional fiber optical plate.

[Explanation of symbols]

1 ... Fiber optic plate, 2 ... Scintillator, 3 ...
Image sensor, 4 ... Radiation source, 5 ... Sample, 6 ... Amplifier, 7 ...
Computer, 8 displays, 100 ... Core, 101
... cladding, 102 ... light absorber, X, X ', X'',
X '''... Radiation, F, F', F '' ... Incident light, B ... Light transmission axis.

Claims (10)

[Claims] 1. A plurality of cores made of a core glass material for propagating incident light, and a clad made of a clad glass material for covering the outer periphery of each core and filling a space between adjacent cores. A fiber optic plate having, wherein the core glass material and the clad glass material contain lead oxide, and the lead oxide content in the core glass material is higher than the lead oxide content in the clad glass material. And, the clad glass material contains 0.3 to 0.3% of lithium oxide.
Fiber optic plate containing 3.0% by weight. 2. The lead oxide content in the core glass material is 54 to 85% by weight, and the lead oxide content in the clad glass material is 27 to 75% by weight. The described fiber optic plate. 3. The fiber optic plate according to claim 1, wherein the difference between the lead oxide content in the core glass material and the lead oxide content in the clad glass material is 10% by weight or more. . 4. The fiber optic plate according to claim 1, wherein a difference between a sag point of the core glass material and a sag point of the clad glass material is within 30 ° C. 5. The light absorber according to claim 1, further comprising a light absorber made of a light absorbing glass material for absorbing light leaked from the core and light incident on the clad. A fiber optic plate according to item. 6. A plurality of cores made of a core glass material for propagating incident light, and a clad made of a clad glass material for covering the outer peripheral portion of each core and filling a space between adjacent cores. A fiber optic plate having, wherein the core glass material and the clad glass material contain lead oxide, and the lead oxide content in the core glass material is higher than the lead oxide content in the clad glass material. And, the clad glass material contains 0.3 to 0.3% of lithium oxide.
Radiation comprising: a fiber optic plate containing 3.0% by weight; a scintillator optically connected to one end of the fiber optic plate; and an imaging element optically connected to the other end of the fiber optic plate. Image detection device. 7. The lead oxide content in the core glass material is 54 to 85% by weight, and the lead oxide content in the clad glass material is 27 to 75% by weight. The radiation image detecting device described. 8. The radiation image detection according to claim 6, wherein the difference between the lead oxide content in the core glass material and the lead oxide content in the clad glass material is 10% by weight or more. apparatus. 9. The radiation image detecting device according to claim 6, wherein a difference between a sag point of the core glass material and a sag point of the clad glass material is within 30 ° C. 10. The fiber optical plate according to claim 6, wherein the fiber optical plate further comprises a light absorber made of a light absorbing glass material for absorbing light leaked from the core and light incident on the clad. The radiation image detecting device according to any one of the above.