JPS5837527A - Photodetector - Google Patents

Abstract

PURPOSE:To reduce the wavelength dependence of radiated light and stably attain photodetection without excess loss by using a quartz glass lod and a quartz optical fiber. CONSTITUTION:An image formation lens 2 is stored in a metallic lens case 1 made of stainless steel or the like. A metallic protection case 3 made of stainless steel or the like is screwed with the lens case at its leading end and a quartz glass lod 4 of which both the ends are ground like a mirror is stored in the protection case 3. The refractive index of the center part of the glass lod 4 is larger than that of the peripheral part and an optical guide layer is formed on the center part. The quartz glass lod 4 is coupled with a quartz optical fiber 5 through a connector 8 and the optical fiber 5 is connected to a detection processing part 6 of a radiation thermometer.

Description

[Detailed description of the invention] The present invention relates to a photodetection device suitable for.

Measures the temperature of high-temperature objects such as heating furnaces and hot-rolled steel plates without contact. As a method for determining the temperature, the wavelength dependence of the spectral radiation characteristics of the object is dependent on the temperature of the object, as shown in Figure 1. A needle is used.

If the object to be measured cannot be directly observed through an optical system with a radiation temperature of 10, because the object to be measured is far away, located in a recessed and narrow place, or the ambient temperature is high, use some other means to observe the object to be measured. The emitted light from the object to be measured must be detected and guided to the emitted temperature needle.

Therefore, in conventional radiation temperature needles, the radiation light from the object to be measured is picked up by a bundle fiber made up of a large number of multi-component glass fibers of 100 to 200 f/16, and this radiation light is guided to the detection processing section. Ta. However, although multicomponent glass fiber itself has a melting point of about 700°C, since an organic resin ring is used for the end treatment of the bundle fiber tip, the heat resistance of the bundle fiber tip is 100 to 200°C. ℃, and when measuring the temperature close to a high-temperature object, a cooling mechanism such as water cooling or air cooling ring was required. In addition, multi-component glass fibers have problems such as not being able to provide a sufficient transmission distance due to large losses, and having to compensate for wavelength dependence in the detection processing section because the loss is highly dependent on liquid length. Furthermore, since the geometric measurement range of the object to be measured is determined by the numerical aperture of the nine fibers used, there is the problem that sufficient resolution cannot be obtained. In addition, in order to be able to measure the temperature WL close to a high-temperature object without exposing the tip of the bundle fiber to a high-temperature atmosphere, a glass rod is connected to the tip of the bundle fiber, and the emitted light is picked up by this glass rod. It is also practiced to send the signal to the detection processing unit via the multi-component bundle fiber. However, since the glass rod in this case is just a rod, if the outer periphery gets dirty, light will leak out and the transmission characteristics will become unstable, and if the refractive index of the atmosphere changes, the field of view will change. Yes, constant hat- was causing deterioration.

The present invention was developed in view of one point during light detection related to the above-mentioned nine radiation temperature needles), and is capable of detecting not only the radiation temperature needle but also the radiation of high temperature objects such as position detection and passage detection of hot objects. To provide a photodetection device that has little wavelength dependence on emitted light, has low loss, stably transmits p, and is heat resistant, for a needle-side i device that obtains information about high-temperature objects. - aim.

The photodetection device of the present invention that achieves the above object includes a silica-based glass rod having a light guide layer in the center and receiving light from an object to be measured, and a silica-based glass rod coupled to the quartz-based glass U/O output tube. It is equipped with a Kuishi II & system optical fiber. In order to freely select the field of view, it is preferable to provide a quartz-based imaging lens in front of the quartz-based glass rod.

The present invention will be explained below based on the drawings. FIG. 2 shows an embodiment in which the present invention is applied to a radiation thermometer, with the photodetecting tip being acid-precipitated, and FIG. 3 (Xun.

佽) C is a 11 side view and a front view for explaining a quartz-based glass rod having a light guide layer in the center.

In FIG. 2, a metal lens case made of lFi stainless steel is shown, and the imaging lens 2 is housed in this case. 3
is a protective case made of stainless steel, which can be screwed onto the lens case 1 at its tip, has both end surfaces polished to a mirror finish, and has a quartz-based glass rod 4 housed inside. This silica-based glass red 4 is not just a glass rod, but has a refractive index distribution in which the center m5011 refractive index is higher than that of the periphery.Due to this refractive index distribution, an original guide layer is formed at the center, and the outer periphery Regardless of the refractive index change Kr1l of the dirty atmosphere, light enters with a constant field of view and can be stably transmitted without leaking to the outside. Hereinafter, this quartz sand rod 4 will be referred to as an optical rod, and since it is made of quartz, it has little wavelength dependence and high heat resistance. 5#i A bundle 7 Eyeper is made by bundling a large number of rounded quartz glass 7 Eyepers, such as 21 cores or 49 cores, to increase the amount of transmitted light.The connector 8 installed previously is screwed into the base end of the protective case 3. By doing so, it is coupled to the optical rod 4. In this embodiment, the base of the bundle fiber 5 is coupled to the detection processing section of the ore radiation temperature needle, and sends the radiation to the photoelectric conversion section thereof. Note that 7 in FIG. 2 is a support fitting for the optical rod 4.

With such a configuration, the imaging lens 2 is also made of quartz and all the glass parts are made of quartz, and the lens case l and the protective case 3 are made of stainless steel, and the bonding of the metal part and the glass part and the terminal treatment of the bundle fiber 4 are made. However, the heat resistance of the tip of the photodetector is approximately 10
00℃, which is a significant improvement. In addition, the optical rod 4Fi can receive the synchrotron radiation with a fixed field of view and send it to the quartz-based bundle fiber 5 without leaking to the outside.
The fiber bundle 4 and the bundle fiber 5 are both made of quartz and have little dependence on rounding wavelengths and have little transmission loss.
Even if the optical rod 4 or bundle fiber 5 is lengthened, the refractive index of the atmosphere changes, or the outer periphery of the optical rod 4 becomes dirty, the emitted light from the desired part of the high-temperature object is detected and the wavelength The temperature can be stably and reliably sent to the detection processing unit 6 without Kffi, and the temperature measurement accuracy is extremely improved. Furthermore, if the imaging lens 2 is provided in front of the optical rod 4 as in the embodiment, the resolution can be freely set by selecting the focal length of the imaging lens 2, and the temperature of a very small part of the high-temperature object can be set freely. You can measure the average temperature throughout.

To explain further, the optical rod 4 is shown in FIG. 3(a).
, (b) If the refractive index distribution is fii as shown in K, then if it is a step type in which the refractive index n1 of the center part 4m is the refractive index n1 of the peripheral part 4bO, and the refractive index nl)nl of the peripheral part 4b, this is, for example, MCVD method and VAD method for manufacturing optical fiber
It can be made by heating and stretching a step-type optical 7-eye 7-ohm fabric to a predetermined diameter of about 2mm diameter. As a result, it is possible to finish the tip of the photodetector, including the protective case 3, to a small diameter of about 5 to 6 mm.
The tip can be inserted into tight spaces. optical 7tj)
``The required length of V h = 4 varies depending on the surrounding atmospheric temperature, but in production, a length of several tones can be easily obtained (by using optical fiber large-diameter spinning technology), K to obtain the refractive index distribution of the optical rod 4 is:
There is a method of increasing the refractive index of the center 4MO by adding a dopant such as germanium (Ge) or phosphorus CP) to the center 4m, or a method of lowering the refractive index of the periphery 4b by adding fluorine CF) or boron CB) to the periphery 4b. There is a method, but 0.3 to 0.
The latter method is suitable for IK, which also targets extremely short wavelengths such as 4JIm.

Considering the transmission loss, both the optical rod 4 and the bundle fiber 5 #'i are made of quartz, and the manufacturing technology for the 7-IPA base material for low-loss communication can be applied to the manufacture of the base material. Loss is example tc1. sJImK&iteo, s dB, 4ml[te6] Even at short wavelengths, there is almost no absorption loss due to impurities in the form of metal ions, and the loss is only due to L-ray scattering, which is proportional to -4 on the light side. For example, at 0.6J1111, l OdB/1
-Therefore, when using a quartz base material, optical detection devices can obtain low loss and flat transmission characteristics over a wide wavelength range compared to when using multi-component fibers. Even if the distance between the detection end and the photoelectric conversion processing system is relatively long, in practical use, the amount of waste is not a problem, and the transmittance of the optical rod 4 and bundle 7 eyeper 6 is 0* for the II# color temperature needle. Long dependence! Due to the small value of k, temperature calibration can be performed more easily than when conventional multi-component fibers are used, and there is also the advantage that there is a high degree of freedom in wavelength selection.

By the way, the acceptance angle of optical rod 4! - is given by the following equation (1), which is determined by the refractive index n1 of the rod center portion (core portion) 4m and the refractive index fi dew of the rod peripheral portion (cladding portion) 4b.

2g = 25in-''CFy stone?)...-
・Formula (1) - As an example, if a base material with a refractive index difference of 291 is used, flt" 1,487.111M1.45 f4
If so, the meaning of light reception is 34°. Therefore, when the distance to the object to be measured is 2 m, the diameter of the object to be measured is 1.
Radiant light within a range of 200 nm is incident on the optical rod 4. If the temperature of the object to be measured is within a narrow range, it is necessary to restrict the visibility, but this purpose can be achieved by mounting the imaging lens 2 in front of the optical rod 40 as in the embodiment. In this case, if the diameter of the core s4m of the optical rod 4 is D1 and the focal length of the imaging lens 2 is f, then the new acceptance angle 2φ is 2φ−ji
5in-"(D/!1) -= is given by equation (2). -For example, ゛D-1.5swI, f depth 5
0 steel has a narrow field of view of 2φ-1,'Io and 1
k) Extremely capable of measuring temperatures in a narrow range. Of course, any angle of view can be obtained by replacing the imaging lens 2 and changing the focal length of the lens.

Note that when the imaging lens 2 is used, it is necessary that a real image of the object to be measured be formed on the tip surface of the optical radar 40 via the lens system.

As the imaging lens 2, it is desirable to use a quartz lens in view of improving heat resistance and reliability Q.

The above describes one embodiment of the present invention, taking as an example the case where it can be used in a radiation thermometer. A needle m that uses light emitted from the object to obtain information about the object to be measured.
*It is not a moat to say that it is applied to the place.

After summarizing the effects of the present invention, (1) Since the optical transmission system is made of quartz-based glass material, the distance between the photodetector and the photoelectric conversion processing section can be lengthened.

(2) Since a quartz-based optical rod with a light guide layer in the center is used, the heat resistance of light detection is greatly improved, and the field of view and loss are stabilized.

[Brief explanation of the drawing]

FIG. 1 is a spectral radiation characteristic diagram with respect to temperature for explaining the principle of a radiation thermometer, FIG. 2 is a partially broken configuration diagram of one embodiment of the present invention, and FIG. 3(a). (b)i! FIG. 2 is a plane view and a front view showing an example of an optical rod. In the drawings, 1 is a lens case, 2 is an imaging lens, 3 is a protective case, and 4 is a glass rond with a light guide layer in the center.
A bundle tour 6 is a detection processing section, and 8 is a connector. Patent applicant: Sumito Electric Industry Co., Ltd. Representative: Shibe Mitsuishi, legal advisor (and 1 other person) Figure 1 Figure 2 Figure 3 (0) - (b)

Claims (1)

[Claims] A light detection device comprising: a silica-based glass rod having a light guide layer in the center and receiving light from an object to be measured; and a silica-based optical fiber coupled to the output side of the silica-based glass rod.