JP2004061417A - UV sensor - Google Patents

Abstract

An object of the present invention is to detect ultraviolet rays according to a desired wavelength range.
An ultraviolet sensor (10) of the present invention is a sensor for detecting ultraviolet light in a desired wavelength region, and is formed by controlling the amount of nitrogen contained in a diamond crystal. And a first diamond photodiode 11 that outputs a detection value according to the amount of nitrogen, which is created by controlling the amount of nitrogen contained in the diamond crystal, absorbs ultraviolet light having a wavelength of λ2 (λ2> λ1) or less, and responds to the amount of ultraviolet light. A second diamond photodiode 12 that outputs a detection value, and a detection value of the first diamond photodiode 11 is subtracted from a detection value of the second diamond photodiode 12, and the subtraction value is used as an ultraviolet light amount of wavelengths λ1 to λ2. And ultraviolet detecting means 13 and 14 for outputting as detection values according to the above.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultraviolet sensor for detecting ultraviolet light in a desired wavelength range.
[0002]
[Prior art]
In recent years, the ozone layer depletion in the stratosphere due to environmental pollution has progressed, and the amount of ultraviolet (UV-A, UV-B) that is harmful to the human body among solar ultraviolet rays has increased, reaching the ground surface. The possibility of ultraviolet rays (UV-C) having strong physiological effects reaching the ground surface has emerged. UV-A is ultraviolet light in the wavelength region of 320 nm to 400 nm, and its actions include promoting plant growth and affecting skin surface cells (melanin pigment blackening action, sunburn) and the like. UV-B is ultraviolet light in the wavelength range of 280 nm to 320 nm, which inhibits the growth of plants and plankton, inhibits photosynthesis (e.g., reduces harvesting), increases the probability of occurrence of skin cancer (such as melanoma), and impairs vision (keratitis, cataract, etc. ), And immunity (increase in infectious diseases in the tropics). Considering the biological effects and the increase in the amount reaching the surface, ultraviolet rays are particularly dangerous. UV-C is ultraviolet light in the wavelength range of 200 nm to 280 nm and hardly reaches the surface of the earth, but has the greatest biological effect, and care must be taken when using an artificial light source for exposure. Its effects include a bactericidal effect, destruction of plant DNA proteins, and an increase in the probability of mutation (sometimes used to create mutant strains).
[0003]
As described above, the UV-A, B, and C ultraviolet rays have different functions, and therefore, it is necessary to select and detect a specific wavelength region according to the situation. At present, a UV sensor having a GaAsP composition manufactured by Hamamatsu Photonics is used as a typical example for UV light detection. As shown in FIG. 5, two types of UV sensors, G5842 and G5842-01, are used. Since G5842 has sensitivity in a wavelength region of 400 nm to 260 nm, UV-A and B can be detected. In addition, since G5842-01 has sensitivity at 300 nm to 270 nm, a part of UV-B can be detected.
[0004]
On the other hand, the amount of UV-A reaching the ground surface is more than 1000 times that of UV-B, and conversely, the biological effect of UV-B is more than 1000 times that of UV-A. Therefore, it is important to accurately grasp the amount of ultraviolet light in a certain wavelength range in order to examine the influence of the ultraviolet light.
[0005]
[Problems to be solved by the invention]
However, with the above-mentioned conventional Hamamatsu Photonics UV sensor, UV-A, UV-B, and UV-C cannot be separately detected, and whether the influence of ultraviolet light is caused by UV-A ultraviolet light, It cannot be determined whether it is caused by UV-B ultraviolet light. For this reason, the necessity and demand for detecting ultraviolet rays separately according to the wavelength ranges of UV-A, UV-B, and UV-C have increased.
[0006]
The present invention has been proposed in view of the above, and an object of the present invention is to provide an ultraviolet sensor capable of detecting ultraviolet light according to a desired wavelength region.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an ultraviolet sensor for detecting ultraviolet light in a desired wavelength region, which is produced by controlling the amount of nitrogen contained in a diamond crystal and emits ultraviolet light having a wavelength of λ1 or less. A first diamond photodiode that absorbs and outputs a detection value according to the amount of ultraviolet light, and a laser diode that is created by controlling the amount of nitrogen contained in the diamond crystal and absorbs ultraviolet light having a wavelength of λ2 (λ2> λ1) or less and absorbs the ultraviolet light. A second diamond photodiode that outputs a detection value corresponding to the amount, and a detection value of the first diamond photodiode subtracted from a detection value of the second diamond photodiode. And an ultraviolet detecting means for outputting as a detection value corresponding to the amount.
[0008]
According to a second aspect of the present invention, there is provided an ultraviolet sensor for detecting ultraviolet rays in a desired wavelength region, wherein the first diamond is formed by controlling the amount of nitrogen contained in the diamond crystal and transmits ultraviolet rays having a wavelength of λ1 or more. A filter, a third photodiode that detects light having a wavelength of λ1 or more transmitted through the first diamond filter, and outputs a detection value according to the amount of light, and a control of the amount of nitrogen contained in the diamond crystal. A second diamond filter that transmits ultraviolet light having a wavelength of λ2 (λ2> λ1) or more, and a fourth photo that detects light having a wavelength of λ2 or more that has passed through the second diamond filter and outputs a detection value corresponding to the amount of light. The detection value of the fourth photodiode is subtracted from the detection value of the third photodiode and the detection value of the third photodiode. And an ultraviolet detecting means for outputting and displaying a detection value corresponding to the amount of ultraviolet light.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a first embodiment will be described with reference to FIGS.
[0010]
FIG. 1 is a diagram showing the classification of diamonds used in the ultraviolet sensor of the present invention, and FIG. 2 is a diagram showing light wavelength-transmittance characteristics for each classification. In FIG. 1, diamond is classified into Ia type, Ib type, IIa type, and IIb type depending on the nitrogen content and the form of its existence. As shown in FIG. Also change. That is, the type IIa has an absorption edge at about 220 nm, and absorbs light having a wavelength shorter than 220 nm and transmits light having a longer wavelength (FIG. 2A). The Ia type has an absorption edge at about 320 nm, and absorbs light having a wavelength shorter than 320 nm and transmits light having a longer wavelength (FIG. 2B). The Ib type has an absorption edge at about 430 nm, and absorbs light having a wavelength shorter than 430 nm and transmits light having a longer wavelength (FIG. 2B). The ultraviolet sensor of the present invention is configured using diamond whose absorption edge changes according to the nitrogen content and the form of its existence.
[0011]
FIGS. 3A and 3B are diagrams schematically showing the configuration of the ultraviolet sensor of the present invention, wherein FIG. 3A shows the wavelength-transmittance characteristic of a diamond photodiode, and FIG. 3B shows the configuration of the ultraviolet sensor. The ultraviolet sensor 10 according to the present invention is a sensor that detects ultraviolet light in a desired wavelength region. As shown in FIG. 3B, two diamond photodiodes 11 and 12, a subtractor 13, a display unit 14, It is composed of
[0012]
The diamond photodiodes 11 and 12 are formed by controlling the amount of nitrogen contained in the diamond crystal. As shown in FIG. 3A, the diamond photodiode 11 absorbs ultraviolet light having a wavelength of λ1 or less and reduces the amount of ultraviolet light. The corresponding detection value is output as an electric quantity, and one of the diamond photodiodes 12 absorbs ultraviolet light having a wavelength of λ2 (λ2> λ1) or less, and outputs a detection value corresponding to the ultraviolet light quantity as an electric quantity. The diamond photodiode includes a pin type and a pn type, a Schottky type, an avalanche type, and the like.
[0013]
The subtractor 13 subtracts the detection value of the diamond photodiode 11 from the detection value of the diamond photodiode 12. This subtraction value corresponds to the amount of ultraviolet light of wavelengths λ1 to λ2. The subtractor 13 outputs the subtraction value, and the display unit 14 displays the output value. Note that the subtractor 13 and the display unit 14 constitute ultraviolet detecting means for detecting desired wavelengths λ1 to λ2.
[0014]
Here, the wavelengths λ1 and λ2 (λ2> λ1) can be set to arbitrary values. However, if λ1 is 220 nm and λ2 is 280 nm, the ultraviolet sensor 10 becomes a sensor for detecting UV-C ultraviolet light, and If λ1 is 280 nm and λ2 is 320 nm, the ultraviolet sensor 10 will be a sensor for detecting UV-B ultraviolet light, and if λ1 is 320 nm and λ2 is 400 nm, the ultraviolet sensor 10 will detect UV-A ultraviolet light. It becomes a sensor.
[0015]
4A and 4B are diagrams schematically illustrating a configuration of an ultraviolet sensor according to the second embodiment, in which FIG. 4A illustrates a wavelength-transmittance characteristic of a diamond filter, and FIG. 4B illustrates a configuration of the ultraviolet sensor. In the above-described first embodiment, diamond is used as a photodiode by utilizing the ultraviolet absorption properties of diamond. In the second embodiment, diamond is used as a filter by utilizing the ultraviolet transmission properties of diamond. Used.
[0016]
The ultraviolet sensor 20 according to the present invention includes two diamond filters 21 and 22, photodiodes (photosensors) 23 and 24 made of, for example, gallium phosphide (GaP), a subtracter 25, and a display unit 26. I have. The diamond filters 21 and 22 are formed by controlling the amount of nitrogen contained in the diamond crystal. As shown in FIG. 4A, the diamond filter 21 transmits ultraviolet light having a wavelength of λ1 or more, Transmits ultraviolet light having a wavelength of λ2 (λ2> λ1) or more.
[0017]
The photodiode 23 detects light having a wavelength of λ1 or more transmitted through the diamond filter 21 and outputs a detection value corresponding to the light amount as an electric quantity. One photodiode 24 has a wavelength of λ2 or more transmitted through the diamond filter 22. The light is detected, and a detection value corresponding to the light amount is output as an electric quantity.
[0018]
The subtracter 25 subtracts the detection value of the photodiode 24 from the detection value of the photodiode 23. This subtraction value corresponds to the amount of ultraviolet light of wavelengths λ1 to λ2. The subtractor 25 outputs the subtraction value, and the display unit 26 displays the output value. Note that the subtractor 25 and the display unit 26 constitute ultraviolet detecting means for detecting desired wavelengths λ1 to λ2.
[0019]
Here, as in the case of the first embodiment, the wavelengths λ1 and λ2 (λ2> λ1) can be set to arbitrary values. However, if λ1 is 220 nm and λ2 is 280 nm, the ultraviolet sensor 10 Is a sensor for detecting UV-C ultraviolet rays. If λ1 is 280 nm and λ2 is 320 nm, the ultraviolet sensor 10 is a sensor for detecting UV-B ultraviolet rays. If λ1 is 320 nm and λ2 is 400 nm, The ultraviolet sensor 10 is a sensor that detects UV-A ultraviolet light.
[0020]
As described above, in the ultraviolet sensor according to the present invention, ultraviolet rays can be detected in accordance with a desired wavelength range. Therefore, ultraviolet rays having different effects on a human body or the like in accordance with wavelengths are referred to as UV-A, UV-B, It can be detected separately for each UV-C. For this reason, it is possible to specify which ultraviolet ray is affected by the ultraviolet ray, so that the cause can be clarified and the countermeasure can be taken effectively.
[0021]
【The invention's effect】
As described above, in the ultraviolet sensor of the present invention, ultraviolet rays can be detected in accordance with a desired wavelength range. B and UV-C can be separately detected. For this reason, it is possible to specify which ultraviolet ray is affected by the ultraviolet ray, so that the cause can be clarified and the countermeasure can be taken effectively.
[Brief description of the drawings]
FIG. 1 is a diagram showing a classification of diamond used for an ultraviolet sensor according to the present invention.
FIG. 2 is a diagram showing light wavelength-transmittance characteristics for each type of diamond used in the ultraviolet sensor of the present invention.
3A and 3B are diagrams schematically illustrating a configuration of an ultraviolet sensor according to the present invention, wherein FIG. 3A illustrates a wavelength-transmittance characteristic of a diamond photodiode, and FIG. 3B illustrates a configuration of the ultraviolet sensor.
4A and 4B are diagrams schematically illustrating a configuration of an ultraviolet sensor according to a second embodiment, in which FIG. 4A illustrates a wavelength-transmittance characteristic of a diamond filter, and FIG. 4B illustrates a configuration of the ultraviolet sensor. is there.
FIG. 5 is a diagram showing sensitivity characteristics of a conventional ultraviolet sensor.
[Explanation of symbols]
Reference Signs List 10 UV sensor 11 Diamond photodiode 12 Diamond photodiode 13 Subtractor 14 Display unit 20 UV sensor 21 Diamond filter 22 Diamond filter 23 Photodiode 24 Photodiode 25 Subtractor 26 Display unit

Claims (2)

In an ultraviolet sensor that detects ultraviolet light in a desired wavelength region,
A first diamond photodiode that is created by controlling the amount of nitrogen contained in the diamond crystal, absorbs ultraviolet light having a wavelength of λ1 or less, and outputs a detection value according to the amount of ultraviolet light;
A second diamond photodiode that is created by controlling the amount of nitrogen contained in the diamond crystal, absorbs ultraviolet light having a wavelength of λ2 (λ2> λ1) or less, and outputs a detection value according to the amount of ultraviolet light;
Ultraviolet ray detecting means for subtracting the detected value of the first diamond photodiode from the detected value of the second diamond photodiode, outputting the subtracted value as a detected value corresponding to the amount of ultraviolet rays of wavelengths λ1 to λ2, and displaying the detected value;
An ultraviolet sensor comprising: In an ultraviolet sensor that detects ultraviolet light in a desired wavelength region,
A first diamond filter created by controlling the amount of nitrogen contained in the diamond crystal and transmitting ultraviolet light having a wavelength of λ1 or more;
A third photodiode that detects light having a wavelength of λ1 or more transmitted through the first diamond filter and outputs a detection value according to the amount of light;
A second diamond filter formed by controlling the amount of nitrogen contained in the diamond crystal and transmitting ultraviolet light having a wavelength of λ2 (λ2> λ1) or more;
A fourth photodiode that detects light having a wavelength of λ2 or more transmitted through the second diamond filter and outputs a detection value according to the amount of light;
Ultraviolet detection means for subtracting the detection value of the fourth photodiode from the detection value of the third photodiode, outputting the subtracted value as a detection value corresponding to the amount of ultraviolet light of wavelengths λ1 to λ2, and displaying the detected value;
An ultraviolet sensor comprising:

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