JPH0452660Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a radiation thermometer using an optical fiber.

<Prior Art> FIG. 3 shows an example of a conventional optical fiber radiation thermometer. In the figure, 30 is a gradient index lens, 12 is an optical fiber, 13 is an optical connector, 4 is a lens, 31 is an optical filter, 5 is a photodetector, 6 is an arithmetic circuit, and the lens 30, the optical fiber 12 and the optical The connector 13 constitutes a sensor probe. In an optical fiber radiation thermometer with a sensor probe configured like this,
The synchrotron radiation emitted from the object to be measured is introduced into the optical fiber 12 by the gradient index lens 30, and then passed through the optical connector 13, the lens 4, and the optical filter 3.
1 and is converted into an electrical signal by a photodetector 5.
This electric signal is applied to an arithmetic circuit 6, subjected to a predetermined arithmetic operation, converted into a temperature, and output. The optical filter 31 is for passing only light of a specific wavelength, and for example, a narrow band interference filter has been used.

<Problems to be solved by the invention> However, in order to improve the performance of the radiation thermometer with the configuration shown in Fig. 3, it is necessary to use a high-performance optical filter 31; Since a high-performance optical filter is very expensive, there is a drawback that the entire radiation thermometer becomes expensive accordingly.

<Means for Solving the Problems> In order to solve the above problems, the present invention uses a rod lens as a sensor probe for an optical fiber radiation thermometer, by drawing a Fresnel pattern on the end face of the rod lens to serve as a radiation receiving surface. The end of an optical fiber is connected to one end face, and an optical connector is attached to the other end of the optical fiber.

The present invention will be described below with reference to Examples.

<Example> FIG. 1 is a configuration diagram of an example of the optical fiber radiation thermometer according to the present invention. In the figure, 10 is a sensor probe, 4 is a lens, 5 is a photodetector, and 6
is an arithmetic circuit. The emitted light from the object to be measured is
Rod lens 11 forming sensor probe 10
The temperature is introduced into the optical fiber 12 via the optical connector 13 and the lens 4, and is detected by the photodetector 5. The temperature is converted by the arithmetic circuit 6 and output.

FIG. 2 is a specific configuration diagram of the sensor probe 10 used in the optical fiber radiation thermometer shown in FIG. In Fig. 2, 11 is a rod lens;
2 is an optical fiber, and 13 is an optical connector. As shown in the figure, a Fresnel pattern A is drawn in a ring shape on the end face of the rod lens 11. Due to this Fresnel pattern A, light of a specific wavelength out of the light emitted from the object to be measured is converged as shown in convergent light B in FIG. 2, and concentrated at a convergent point C. This convergence point C
is located at the center of the other end surface of the rod lens 11, and at this point, the rod lens 11
and an optical fiber 12 are connected. Light of other wavelengths of the synchrotron radiation is C on the central axis of the rod lens 11.
Since the light is converged at a position other than the point, the light of the wavelength converged at the point C, which is the connection point with the optical fiber, enters the optical fiber 12, but the light of other wavelengths is blocked.

The optical fiber radiation thermometer according to the present invention having such a configuration differs from the conventional example shown in Fig. 3 in that a Fresnel pattern is drawn on the light receiving part at the tip of the sensor probe instead of a gradient index lens. The rod lens 11 is used and the optical filter is not used. As mentioned earlier, this is because the sensor probe itself has the function of a narrowband optical filter.In other words, by attaching a Fresnel pattern to the rod lens, only light of a specific wavelength of the emitted light is transmitted. By making the light incident on the fiber, it can be used as a substitute for the optical filter 31 shown in FIG. 3. Fresnel lenses generally have excellent features such as small spherical aberration, light focusing characteristics close to the diffraction limit, and ease of reproduction due to their relief structure. Therefore, inexpensive rod lenses with Fresnel patterns drawn thereon can be mass-produced, and sensor probes constructed using these rod lenses can have a high-performance filter function.

In addition, in FIG. 1, in order to focus the light that has passed through the optical fiber 12 onto the light receiving surface of the photodetector 5,
Even if the optical connector 13 to which the fiber 12 is connected is removed, a gradient index lens is connected in its place, and the lens 4 is removed, the light is focused by the gradient index lens. good. In this case, the sensor probe has a configuration in which a rod lens on which a Fresnel pattern is drawn for receiving radiation light is connected to one end of an optical fiber, and a gradient index lens is connected to the other end of the optical fiber. Furthermore, the sensor probe may have a configuration in which the optical connector 13 is removed from the optical fiber 12 in FIG. In this case, a condensing lens 4 is necessary.

<Effects of the invention> As explained above, in the invention, the sensor probe of the radiation thermometer is constructed using a rod lens on which a Fresnel pattern is drawn.
This sensor probe itself has a high-performance narrowband filter function, so it can
Eliminates the need to use expensive optical filters.
Furthermore, since the rod lens with the Fresnel pattern drawn thereon can be mass-produced at low cost, the present invention makes it possible to realize a sensor probe that can be mass-produced at low cost.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of the optical fiber radiation thermometer, Fig. 2 is a specific block diagram of a sensor probe used in the optical fiber radiation thermometer shown in Fig. 1, and Fig. 3 is a block diagram showing a conventional optical fiber radiation thermometer. FIG. 2 is a configuration diagram of a fiber radiation thermometer. 10... Sensor probe, 11... Rod lens, 12... Optical fiber, 13... Optical connector.

Claims (1)

[Scope of utility model registration request] By connecting an optical fiber to a rod lens with a Fresnel pattern drawn on the end face, a sensor probe is used that allows only light of a specific wavelength to enter the optical fiber out of the light emitted from the object to be measured. Fiber optic thermometer.