JP3221834B2 - Fluorescent glass dosimeter reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluorescent glass dosimeter reader for reading the exposure dose of a fluorescent glass dosimeter element which has been exposed to radiation.

[0002]

2. Description of the Related Art In radiation protection, when installing facilities such as a nuclear reactor, an accelerator, an X-ray generator, and a radioisotope, it is necessary to pay close attention to radiation control.
Then, it is necessary to keep the radiation exposure dose and environmental radiation dose to the facility operation staff and facility users within a predetermined allowable range. For this reason, it is very important to measure the dose individually and quickly by dosimeters carried by facility workers and users, and dosimeters placed at multiple locations in the facility, and to appropriately manage these dose data. It has become.

In a conventional fluorescent glass dosimeter reader, such an exposure dose is read by exciting ultraviolet rays from a UV light source such as a nitrogen gas laser to a fluorescent glass dosimeter element exposed to radiation. This is performed by detecting fluorescence generated from another surface of the fluorescent glass dosimeter element orthogonal to the ultraviolet incident surface.

The output of an ultraviolet excitation light source such as a nitrogen gas laser fluctuates due to factors such as power supply fluctuations and aging. If the excitation ultraviolet light fluctuates accordingly, the intensity of the fluorescence generated from the fluorescent glass dosimeter element also fluctuates. . Therefore, from the viewpoint of compensating for such fluctuations in the intensity of the fluorescence, a part of the excitation ultraviolet rays incident on the radiation-exposed fluorescent glass dosimeter element is incident on the standard fluorescent glass to generate fluorescence also from the standard fluorescent glass, Based on the intensity of the fluorescence, the intensity of the fluorescence generated from the fluorescent glass dosimeter element exposed to the radiation is corrected, and the exposure dose is read.

FIG. 3 is a schematic diagram showing an example of a conventional fluorescent glass dosimeter reader using such a standard fluorescent glass dosimeter element, particularly showing an example of an optical path portion.

In this reader, a nitrogen gas laser 3 emits light to one surface of a radiation-exposed fluorescent glass dosimeter element (hereinafter referred to as a glass element) 1 and one surface of a standard fluorescent glass (hereinafter referred to as a reference glass) 2. Ultraviolet rays 4 are respectively incident on the glass element 1 and the reference glass 2 to generate fluorescent light 5 from another surface orthogonal to the ultraviolet light incident surface, and the fluorescent light 5 is measured.

That is, the ultraviolet light 4 emitted from the nitrogen gas laser 3 bends its optical path by the reflecting mirror 6, passes through the transmission filter 7, and enters the semi-transparent mirror 8 made of quartz glass, where the reflected light and Separate into straight light. this house,
The straight traveling light enters the first diaphragm 9, and only a certain area portion of the light passes through the first diaphragm 9 and enters a certain area on one surface of the glass element 1, and as a result, is orthogonal to the ultraviolet incident surface of the glass element 1. Fluorescence 5 is generated from the other surface. The fluorescent light 5 generated in the glass element 1 as described above is incident on the second diaphragm 10 and only a certain area of the fluorescent light 5 passes through the second diaphragm 10.
Further, the light is received by the photomultiplier tube 14 through the ultraviolet cut filter 11, the red transmission filter 12, and the interference filter 13 in order. Using the output of the photomultiplier tube 14, the arithmetic circuit 15 obtains a measurement output of the exposure dose .

On the other hand, the reflected light separated by the semi-transparent mirror 8 is incident on the third diaphragm 16 and only a certain area of the reflected light passes through the third diaphragm 16, and is incident on a certain area on one surface of the reference glass 2. As a result, the fluorescent light 5 is generated from another surface of the reference glass 2 orthogonal to the ultraviolet incident surface. The fluorescence 5 generated in the reference glass 2 in this manner is
, And only a certain area of the light passes through the diaphragm 17, and further passes through the ultraviolet cut filter 18 and the red transmission filter 19, and is received by the photodiode 20. Using the output of the photodiode 20, the arithmetic circuit 21 obtains an output for correcting the sensitivity in the measurement output. Then, by correcting the above-described measurement output with the sensitivity correction output, the fluctuation of the measurement output due to the fluctuation of the output of the nitrogen gas laser 3 is compensated, and the influence of the fluctuation of the output of the nitrogen gas laser 3 is removed. An accurate measurement output is obtained.

Incidentally, the nitrogen gas laser 3 and the reflecting mirror 6 in the optical path portion of such a fluorescent glass dosimeter reader.
The other parts after the transmission filter 7 are provided in the dark room 22 and constitute a measurement unit. Here, the transmission filter 7 cuts the light other than the ultraviolet light 4 from the nitrogen gas laser 3 so that disturbance light that reaches the dark room 22 and affects the measurement does not enter the dark room 22.
It plays a role of adjusting the intensity of the ultraviolet light 4 incident on the glass element 1 so as to be maintained within a certain allowable range (about 50 to 15 μJ).

For example, when the ultraviolet light 4 is too strong, the center of the fluorescent light 5 in the glass element 1 disappears, and the measured value becomes lower than the actual value. On the other hand, if the ultraviolet light 4 is too weak, the measured values vary due to the influence of noise.

Further, lasers such as the nitrogen gas laser 3
While the number of laser pulse generations has a lifetime, the output tends to decrease over time, regardless of the usage conditions. Therefore, although there is a difference for each laser, when the intensity of the ultraviolet light 4 incident on the glass element 1 falls below a certain set value due to a decrease in the laser output,
Parts inside the laser (laser tube) need to be replaced.

[0012]

However, the conventional apparatus of FIG. 3 having the above configuration has the following problems. That is, in FIG. 3, the transmission filter 7 for allowing the ultraviolet rays 4 to enter the measuring section is in a state where the laser output is relatively strong, that is, the transmittance is such that ultraviolet rays of appropriate intensity can be obtained even in the initial stage of using the laser. , The intensity of the ultraviolet light incident on the glass element 1 in an early period (about one year in the past) falls below a set value.

For example, as a specific example of the conventional device shown in FIG.
Assuming that an initial laser output is 120 μJ when a transmission filter 7 having a transmittance of 45% and a reflecting mirror 6 having a reflectance of 80% are used, the intensity of the ultraviolet light 4 incident on the glass element 1 The nitrogen gas laser 3 is used under the condition that the range of the above is within the range of about 40 to 15 μJ. Under this condition, for example, the intensity of the ultraviolet light 4 incident on the glass element 1 is set to the above-mentioned allowable range (5
Since the laser output in the case of 15 μJ, which is the lower limit of about 0 to 15 μJ), is about 40 μJ, this value is the lower limit of the allowable range of the laser output. That is, the allowable range of the laser output in this case is about 120 to 40 μJ.

The laser output has a lower limit of 40 μm.
When the value falls below J, the laser tube is replaced each time. However, such a replacement of the laser tube requires a special operation such as an optical axis adjustment, so that there is a problem that considerable time and labor are required. In addition, since the laser tube is expensive, such replacement is economically burdensome.

On the other hand, the initial laser output is set to 150
When the intensity is increased to about μJ, the intensity of the ultraviolet light 4 incident on the glass element 1 becomes 50 μJ or more, which is too inconvenient. In such a case, the intensity of the ultraviolet light 4 incident on the glass element 1 is reduced to 4 which is the upper limit of the allowable range, by taking measures such as deliberately shifting the optical axis of the laser from the optimum position.
It is necessary to reduce it to about 0 μJ. However, in this case, in addition to the work of shifting the optical axis of the laser, it is necessary to adjust the optical axis of the laser to the optimal position when the laser output is reduced. Requires a considerable amount of time and labor for the special work of the present invention, which is inconvenient.

As described above, in the conventional fluorescent glass dosimeter reader, an ultraviolet ray having an appropriate intensity can be obtained even in an initial stage where the laser output is relatively strong, as a transmission filter for allowing the ultraviolet ray to enter the measuring section. Since a filter having such a transmittance is used, it is necessary to replace the laser tube at an early stage, and this replacement operation is a heavy burden in terms of time, labor, and economy.

The present invention has been proposed to solve the above-mentioned problems of the prior art.
In particular, by improving the configuration of the transmission filter that allows the ultraviolet light to enter the measurement unit including the glass element, the laser output can be extended without the need to perform special operations such as optical axis adjustment, and the laser tube replacement period can be extended. It is an object of the present invention to provide a fluorescent glass dosimeter reader capable of reading the exposure dose of the fluorescent glass dosimeter element with high accuracy.

[0018]

In order to achieve the above object, a fluorescent glass dosimeter reader according to the present invention comprises a light source for generating ultraviolet light, and a fluorescent glass for measurement which generates fluorescent light by incidence of ultraviolet light. A dosimeter element, and transmission filter means disposed between the light source and the fluorescent glass dosimeter element and transmitting only light of a specific wavelength and entering the fluorescent glass dosimeter element, wherein the fluorescent glass dosimeter element In the fluorescent glass dosimeter reader configured to read the exposure dose of the fluorescent glass dosimeter element by detecting the fluorescence from the device, the transmission filter means has the following configuration.

According to the first aspect of the present invention, the transmission filter means has a plurality of transmission filters having transmittances different from each other, and the plurality of transmission filters are provided by the light source.
Increases the transmittance of ultraviolet rays when the output of external radiation decreases
So that they can be switched to each other.

According to the first aspect of the present invention having the above-described structure, the plurality of transmission filters can reduce the transmittance of ultraviolet rays.
By switching to raise , the transmittance of the transmission filter means can be easily changed without the necessity of performing special work such as optical axis adjustment, and the laser with respect to the permissible range of the intensity of ultraviolet light incident on the fluorescent glass dosimeter element. The allowable range of output can be expanded. That is, in the initial stage where the laser output is relatively strong, the intensity of the ultraviolet light incident on the fluorescent glass dosimeter element can be suppressed to the upper limit or less of the allowable range by using a transmission filter having a relatively low transmittance. . Further, when the laser output is reduced, the intensity of the ultraviolet light incident on the fluorescent glass dosimeter element can be maintained at or above the lower limit of the allowable range by using a transmission filter having a relatively high transmittance.

According to the second aspect of the present invention, the transmission filter means has a filter holder holding a plurality of transmission filters having different transmittances from each other. The filter holder has a plurality of operation positions for adjusting each of the plurality of transmission filters on the optical path of the ultraviolet light from the light source, and is configured to be switchable between the plurality of operation positions.

According to the second aspect of the present invention having the above configuration, in addition to the operation and effect of the first aspect, the transmission filter can be easily manufactured by switching the operation position of the filter holder. Can be switched to When such a filter holder is used, the operability is excellent and the configuration is simple.

According to the third aspect of the present invention, the transmission filter means has a plurality of filter holders each holding one or more transmission filters. Each of the plurality of filter holders takes a plurality of operation positions including an operation position for aligning the transmission filter of the filter holder on the optical path of the ultraviolet light from the light source, and is switchable between the plurality of operation positions. Be composed.

According to a fourth aspect of the present invention, in the third aspect, at least one of the plurality of filter holders holds a plurality of transmission filters having transmittances different from each other.

The invention according to claim 5 is the invention according to claim 3 or 4.
In the described invention, one or more of the plurality of filter holders includes an operating position for aligning a portion without the transmission filter on an optical path of ultraviolet light from the light source.

According to the third to fifth aspects of the present invention having the above configuration, in addition to the functions and effects of the first aspect, the present invention further provides a combination of a plurality of operating positions of a plurality of filter holders. In addition, it is possible to widen the range of selection of the transmittance of the transmission filter means as a whole, and it is possible to select a more appropriate transmittance according to the stage of the decrease in the laser output. For example, even when two filter holders each have two operation positions, four transmittances can be selected. In this case, the transmittance of the transmission filter means as a whole can be gradually increased in four stages according to the degree of reduction in the laser output.

[0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
One embodiment of a fluorescent glass dosimeter reader to which the described invention is applied will be described with reference to FIGS. Here, FIG. 1 is a configuration diagram schematically showing an optical path portion of the fluorescent glass dosimeter reader, FIG. 2 is a diagram showing the transmission filter system, (A) is a perspective view, and (B) is a sectional view. is there. [1. Configuration] [1-1. Configuration of Optical Path Portion] As shown in FIG. 1, in the present embodiment, the transmission filter 7 of the conventional device shown in FIG. 3 is replaced with a transmission filter system (transmission filter means) 30, and the reflection mirror 6 is omitted. The configuration is such that the ultraviolet light 4 from the nitrogen gas laser 3 is directly incident on the transmission filter system 30, and the other parts are shown in FIG.
The configuration is the same as that of the conventional device.

That is, on the optical path of the ultraviolet light 4 from the nitrogen gas laser 3, the transmission filter system 30 and the semi-transmission mirror 8 are sequentially arranged. The first diaphragm 9 and the glass element 1 are sequentially arranged on the optical path of the straight light of the semi-transparent mirror 8. The glass element 1 generates the fluorescent light 5 from the other surface orthogonal to the ultraviolet light incident surface by the incident ultraviolet light 4, and the second diaphragm 10, the ultraviolet light cut filter 11, the red light A transmission filter 12, an interference filter 13, and a photomultiplier 14 are sequentially arranged. The photomultiplier tube 14 is connected to an arithmetic circuit 15 for obtaining a measurement output of the exposure dose .

A third diaphragm 16 and a reference glass 2 are sequentially arranged on the optical path of the reflected light from the semi-transparent mirror 8. The reference glass 2 generates fluorescent light 5 from another surface orthogonal to the ultraviolet light incident surface due to the incident ultraviolet light 4, and on the optical path of the fluorescent light 5,
A fourth diaphragm 17, an ultraviolet cut filter 18,
A red transmission filter 19 and a photodiode 20 are sequentially arranged. And this photodiode 2
To 0, an arithmetic circuit 21 for obtaining an output for sensitivity correction in the measurement output is connected.

Further, in the optical path portion of such a fluorescent glass dosimeter reader, portions other than the nitrogen gas laser 3 after the transmission filter system 30 are provided in the dark room 22 to constitute a measuring section. Here, similarly to the conventional transmission filter 7, the transmission filter system 30 cuts the disturbance light so as not to enter the dark room 22, and reduces the intensity of the ultraviolet light 4 incident on the glass element 1 within a certain range. (Approximately 50 to 15 μJ). Hereinafter, the configuration of the transmission filter system 30 will be described. [1-2. Configuration of Transmission Filter System] As shown in FIGS. 2A and 2B, the transmission filter system 30 of the present embodiment includes a pair of covers 31 and 32 provided on the side wall 23 of the dark room 22 and A pair of covers 31 and 3
It has two filter holders 33 and 34 inserted between the two. Here, circular openings 31a and 32a of the same size for passing the ultraviolet light 4 are provided on the optical path of the ultraviolet light 4 from the nitrogen gas laser 3 of the pair of covers 31 and 32.
Is provided. Two filter holders 33, 34
Are vertically elongated flat plates having the same dimensions, and a pair of covers 3
It is possible to set the mirrors 1 and 32 by inverting in the longitudinal direction. That is, each filter holder 3
3 and 34 are each configured to take two operating positions. Then, the first filter holder 33 is
At two locations in the longitudinal direction, that is, at each of the two operating positions, they overlap on the optical path of the ultraviolet light 4 from the nitrogen gas laser 3 (therefore, a pair of covers 31, 32).
(Which respectively overlap the pair of openings 31a and 32a) have circular filters 35 and 36 having the same dimensions and low transmittance and high transmittance. Second filter holder 34
Similarly, each has circular filters 37 and 38 having the same dimensions of low transmittance and high transmittance. These filter portions 35 to 38 are larger in diameter than the openings 31a and 32a of the pair of covers 31 and 32 described above.

More specifically, the first filter holder 33
The low transmittance filter section 35 is constituted by a transmission filter having a transmittance of about 45%, and the high transmittance filter section 36 is constituted by an opening having a transmittance of 100% without a transmission filter. Therefore, the first filter holder 33 has a low transmittance position where the low transmittance filter portion 35 having a transmittance of about 45% overlaps the openings 31 a and 32 a of the covers 31 and 32 on the optical path of the ultraviolet light 4, The 100% high transmittance filter section 36 is configured to take two operation positions, that is, a high transmittance position overlapping the openings 31a and 32a of the covers 31 and 32 on the optical path of the ultraviolet light 4.

The low transmittance filter portion 37 of the second filter holder 34 is formed of a transmittance filter having a transmittance of about 45%, and the high transmittance filter portion 38 is provided with a transmittance of 80%.
It is composed of a degree of transmission filter. Therefore, the second filter holder 34 has a low transmittance filter section 37 having a transmittance of about 45, and the cover 31 and the cover 31 on the optical path of the ultraviolet light 4.
A low transmittance position overlapping the 32 openings 31a and 32a;
The high transmittance filter 38 having a transmittance of about 80% is
Are configured to take two operation positions, that is, a high transmittance position overlapping the openings 31a and 32a of the covers 31 and 32 on the optical path of. [2. Operation] Next, the operation of the fluorescent glass dosimeter reader according to the present embodiment having the above-described configuration will be described. [2-1. Operation of Optical Path] First, the ultraviolet light 4 emitted from the nitrogen gas laser 3 passes through the transmission filter system 30 and enters the semi-transparent mirror 8 made of quartz glass, where it is separated into reflected light and straight-ahead light. . Among them, the straight light enters the glass element 1 via the first diaphragm 9, and as a result, the fluorescent light 5 is generated from another surface of the glass element 1 orthogonal to the ultraviolet 4 incident surface. The fluorescent light 5 passes through the second diaphragm 10, the ultraviolet 4 cut filter 11, the red transmission filter 12, and the interference filter 13, and is received by the photomultiplier 14. Using the output of the photomultiplier tube 14, the arithmetic circuit 15 obtains a measurement output of the exposure dose of the glass element 1.

On the other hand, the reflected light separated by the semi-transparent mirror 8 is incident on the reference glass 2 via the third diaphragm 16, and as a result, the fluorescent light is reflected from another surface of the reference glass 2 orthogonal to the ultraviolet 4 incident surface. 5 occurs. The fluorescent light 5 is received by the photodiode 20 through the fourth diaphragm 17, the ultraviolet 4 cut filter 18, and the red transmission filter 19 in order. Using the output of the photodiode 20, the arithmetic circuit 21 obtains an output for correcting the sensitivity in the measurement output. Then, by correcting the above-described measurement output with the sensitivity correction output, the fluctuation of the measurement output due to the fluctuation of the output of the nitrogen gas laser 3 is compensated, and the influence of the fluctuation of the output of the nitrogen gas laser 3 is removed. An accurate measurement output is obtained. [2-2. Operation of Transmission Filter System] In the transmission filter system 30 of the present embodiment, by inserting two filter holders 33, 34 between a pair of covers 31, 32, these filter holders 33, 34 are inserted.
Can be easily set at the low transmittance position or the high transmittance position. In this case, each filter holder 33, 34
The switching of the operating position of the filter holders 33, 34
Can be easily performed simply by reversing

In this case, the transmission filter system 30
Depending on the combination of the operation positions of the two filter holders 33 and 34, the mechanism as a whole has four types of transmittance, that is, a transmittance of about 20%, a transmittance of about 36%,
It has a transmittance of about 45% and a transmittance of about 80%.

In this case, the transmittance of about 20% corresponds to both filter holders 33,
34 are set at the low transmittance position, and the low transmittance filter portions 35 and 37 of about 45% are superposed (45).
% X 45%). For the transmittance of about 36%, the first filter holder 33 is set at the low transmittance position, and the second filter holder 34 is set at the high transmittance position. It is obtained by overlapping the high transmittance filter sections 38 of about 80% (45% × 80%). For the transmittance of about 45%, the first filter holder 33 is set at the high transmittance position and the second filter holder 34 is set at the low transmittance position, and the 100% high transmittance filter units 36 and 45 are set. % By overlapping (100% × 45%). The transmittance of about 80% is obtained by using both filter holders 33,
34 are set at the high transmittance positions, and the 100% high transmittance filter portion 36 and the 80% high transmittance filter portion 38 are overlapped (100% × 80%).

According to the transmission filter system 30 having the four transmittances as described above, by selecting an appropriate transmittance according to the level of the laser output, the ultraviolet light incident on the glass element 1 can be selected. The allowable range of the laser output with respect to the allowable range of the intensity of No. 4 (about 50 to 15 μJ) can be expanded.

For example, first, the transmission filter system 30
Is set to about 20%, assuming that the initial laser output is 120 μJ, the intensity of the ultraviolet light 4 incident on the glass element 1 must be within the range of about 25 to 15 μJ. The gas laser 3 will be used. Under this condition, for example, the intensity of the ultraviolet light 4 incident on the glass element 1 is within the above-mentioned tolerance (50).
The laser output in the case of 15 μJ, which is the lower limit of about 15 μJ, is about 75 μJ. Therefore, the transmission filter system 30 can be used with the transmittance of about 20% until the laser output becomes about 75 μJ.

Next, when the laser output drops to about 75 μJ, the transmittance of the transmission filter
When it is changed to about 6%, the intensity of the ultraviolet light 4 incident on the glass element 1 becomes about 27 μJ, and the output of the laser apparently increases. Under this condition, when the intensity of the ultraviolet light 4 incident on the glass element 1 is reduced to about 15 μJ, the laser output is about 45 μJ. Therefore, the transmission filter system 30 can be used with the transmittance of about 36% until the laser output becomes about 45 μJ.

Subsequently, when the transmittance of the transmission filter system 30 is changed to about 45% when the laser output is reduced to about 45 μJ, the intensity of the ultraviolet light 4 incident on the glass element 1 becomes about 20 μJ. . Under these conditions, the intensity of the ultraviolet light 4 incident on the glass element 1 is 15 μm.
When the laser output is reduced to about J, the laser output is about 35 μJ. Therefore, the transmission filter system 30 can be used with the transmittance of about 45% until the laser output becomes about 35 μJ.

Further, when the transmittance of the transmission filter system 30 is changed to about 80% at the stage when the laser output is reduced to about 35 μJ, the intensity of the ultraviolet light 4 incident on the glass element 1 becomes about 25 μJ. Under these conditions, the intensity of the ultraviolet light 4 incident on the glass element 1 is 15 μm.
When the laser output is reduced to about J, the laser output is about 20 μJ. Therefore, the transmission filter system 30 can be used with the transmittance of about 80% until the laser output becomes about 20 μJ.

As described above, in the present embodiment,
According to the level of the laser output, the transmission filter system 3
By switching the transmittance of 0, the laser output becomes 20
Until reduced to about μJ, the nitrogen gas laser 3 can be used as it is. That is, the allowable range of the laser output of the conventional device shown in FIG. 3 is about 120 to 40 μJ, but the allowable range of the laser output in the present embodiment is as wide as about 120 to 20 μJ. It can be used up to about half the low output area of the past.

Therefore, in the present embodiment, even if the laser output is reduced to about 40 μJ, the intensity of the ultraviolet rays 4 incident on the glass element 1 does not become insufficient, and the laser tube must be replaced at this time as in the conventional apparatus. No need to do.
That is, it is not necessary to replace the laser tube until the laser output drops to about 20 μJ, and the nitrogen gas laser 3 can be used continuously. [3. Effect] As described above, according to the present embodiment, 2
By simply switching the operation positions of the two filter holders 33 and 34, the transmittance of the entire transmission filter system 30 can be easily changed. In this case, special work including mechanical and electrical adjustment such as optical axis adjustment is not required, and workability is excellent.

By changing the transmittance as described above, the allowable range of the laser output can be broadened as described above. In particular, the laser output of the nitrogen gas laser 3 is reduced to the lower limit of the conventional allowable range. Nitrogen gas laser 3 until it drops to about 20 μJ, which is half of a certain 40 μJ
Can be used continuously. As a result, the replacement period of the laser tube can be made longer than before, so that the number of special operations such as optical axis adjustment required at the time of replacement can be reduced, and the number of expensive laser tubes used is reduced. Therefore, the economic burden is reduced. [4. Other Embodiments] The present invention is not limited to the above embodiments, and a specific configuration of the transmission filter system can be appropriately selected. For example, three or more filter holders are used to configure more combinations, or two filter holders are used to configure three or more transmission filter units. It is also possible. In the case of such a configuration, it is possible to change the transmittance more finely.

Conversely, only one filter holder having two transmission filter sections having different transmittances is used, and only the filter holder is inverted, or only two transmission filters having different transmittances are used. A configuration in which the transmission filter is used and only this transmission filter is switched is similarly possible. Even in the case of such a configuration, the transmittance can be changed, so that the allowable range of the laser output can be expanded as compared with the related art, and the transmission filter means can be further simplified.

When two or more transmission filter portions are formed in one filter holder, including the above-described embodiment and the above-described modified example, the filter holder is formed in a circular shape and its circumferential direction is changed. It is also possible to provide a transmission filter section at equal intervals and to switch the operation position by rotating the filter holder. With such a configuration, workability can be further improved.

On the other hand, a light source other than a nitrogen gas laser can be used as a light source for generating ultraviolet light. Further, specific configurations of other optical parts, detection means, arithmetic circuits, and the like can be freely selected. For example, similarly to the conventional apparatus of FIG. 3, a configuration using a reflecting mirror between the laser and the transmission filter means is also possible. In addition, the present invention can be implemented with various modifications without departing from the scope of the invention.

[0047]

As described above, in the present invention, a plurality of transmission filters having different transmittances from each other are used as transmission filter means for allowing the ultraviolet rays from the light source to enter the measuring section including the glass element . UV irradiation output
The laser tube can be switched to each other so as to increase the transmittance of the ultraviolet light when the laser beam is lowered, thereby expanding the allowable range of the laser output without performing any special operation such as optical axis adjustment. It is possible to provide a high-precision fluorescent glass dosimeter reader capable of lengthening the replacement period of the glass element and reading the exposure dose of the glass element with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a fluorescent glass dosimeter reader according to the present invention.

FIG. 2 is a perspective view (A) and a cross-sectional view (B) showing the transmission filter system of FIG.

FIG. 3 is a configuration diagram showing an example of a conventional fluorescent glass dosimeter reader.

[Explanation of symbols]

 1: Glass element (radiation-exposed fluorescent glass dosimeter element) 2: Reference glass (standard fluorescent glass) 3: Nitrogen gas laser 4: Ultraviolet light 5: Fluorescence 6: Reflective mirror 7: Transmission filter 8: Semi-transparent mirror 9, 10, 16, 17: Diaphragm 11, 18: UV cut filter 12, 19: Red transmission filter 13: Interference filter 14: Photomultiplier tube 15, 21: Operation circuit 20: Photodiode 22: Dark chamber 23: Side wall 30: Transmission filter system 31, 32: Cover 31a, 32a: Opening 33, 34: Filter holder 35, 37: Low transmittance filter 36, 38: High transmittance filter

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01T 1/06

Claims (5)

(57) [Claims] 1. A light source for generating ultraviolet light, a fluorescent glass dosimeter element to be measured for generating fluorescence upon incidence of ultraviolet light, and a light of a specific wavelength disposed between the light source and the fluorescent glass dosimeter element. A fluorescent filter configured to transmit only the light to the fluorescent glass dosimeter element and to detect the fluorescent light from the fluorescent glass dosimeter element to read the exposure dose of the fluorescent glass dosimeter element. In the glass dosimeter reader, the transmission filter means has a plurality of transmission filters having transmittances different from each other, and the plurality of transmission filters are provided with ultraviolet light of the light source.
Increase the transmittance of ultraviolet rays when the output power decreases
A fluorescent glass dosimeter reader which is configured to be switchable with each other. 2. The transmission filter means has a filter holder holding a plurality of transmission filters having different transmittances from each other, and the filter holder transmits each of the plurality of transmission filters to ultraviolet light from the light source. 2. A system according to claim 1 , wherein a plurality of operation positions are set to be adjusted on a road, and switching is possible between the plurality of operation positions.
Fluorescent glass dosimeter reader. 3. The transmission filter means includes:
A plurality of filter holders each holding one or more transmission filters, each of the plurality of filter holders including a plurality of operation positions including an operation position for adjusting the transmission filter of the plurality of filter holders on an optical path of ultraviolet light from the light source. 2. The fluorescent glass dosimeter reader according to claim 1, wherein the fluorescent glass dosimeter is configured to be switchable between the plurality of operating positions . 4. The fluorescent glass dosimeter reader according to claim 3, wherein one or more of said plurality of filter holders hold a plurality of transmission filters having different transmittances from each other. 5. The apparatus according to claim 3, wherein one or more of the plurality of filter holders includes an operating position for aligning a portion without the transmission filter on an optical path of ultraviolet light from the light source. Fluorescent glass dosimeter reader.