JPH0136049B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A blackbody furnace is a device that obtains blackbody radiation, and is indispensable and important for the calibration of radiation thermometers, optical pyrometers, and the like.

If there were a perfect black body, the radiation emitted from its surface would be black body radiation, so there would be no need for a black body furnace, but a perfect black body does not exist. Also, there is no perfect reflector that completely reflects the radiation reaching its surface. All real objects are neither perfect black bodies nor perfect reflectors, but have the property of emitting and reflecting some amount of all wave radiation.

When an object exists on the inner surface of the cavity wall and inside the cavity, the temperature of the object is uniformly t°C,
If a part of the inner surface of a wall or an object inside a cavity has the property of emitting radiation of all wavelengths to some extent, the radiation inside the cavity can be said to be a blackbody radiator with a temperature of t°C. , known in thermodynamics.

The radiation emitted from a small hole in such a cavity is completely black, with the same shape and size as the small hole, if changes in the radiation inside the cavity due to radiation entering and leaving the small hole are ignored. It is also known that radiation is equivalent to radiation from the body surface. A cavity with small holes from which blackbody radiation can be obtained is a blackbody furnace. Therefore, in order to be a blackbody furnace, a small hole that satisfies the above conditions must be made in a cavity made of an appropriate real object, and the hole must be maintained at a predetermined uniform temperature. .

It is quite difficult, if not impossible, to maintain a precisely uniform temperature across the walls of the cavity. The present invention provides a blackbody furnace whose temperature can be easily controlled.

If there is a perfect reflector, if most of the cavity is made up of perfect reflectors and part of it is made up of objects that emit radiation of all wavelengths (which can be a perfect black body or a real object), then it will be perfect. Since the reflector has nothing to do with absorption or emission of radiation, no matter what the temperature of the part of the perfect reflector is, it becomes a black body furnace with a temperature of t° C. of some parts that are not perfect reflectors.

By analogy, if we assume that a part of the inner surface of the cavity wall or an object within the cavity has as high an emissivity as possible, and that the other parts of the inner surface of the cavity have as low an emissivity as possible, then the black body of the former If the temperature of the area close to is maintained at a predetermined temperature t℃ with precision,
It is thought that by simply keeping the temperature of the latter part with good reflectivity at that temperature, a blackbody furnace of t° C. can be obtained.
The facts are also true.

When we add irregularities to the surface of an object with high emissivity,
Furthermore, since the effective emissivity increases to some extent, it should be made uneven if possible.

Examples of materials with high emissivity include iron oxide, copper oxide, and nickel oxide, and examples of materials with low emissivity include gold plating, aluminum oxide, and porcelain.

The drawing is a sectional view showing an embodiment of a blackbody furnace according to the present invention, in which 1 is a radiator made of a material with high emissivity, 2 is an inner wall made of a material with low emissivity, and 3 is a radiator made of a material with low emissivity. is a small hole through which black body radiation is emitted to the outside; 4 is a thermocouple for detecting the temperature of the radiator 1; 5 is a conductor for heating the radiator 1;
7 is a thermocouple for detecting the temperature of the inner wall 2;
is a conducting wire for heating the inner wall 2 (however, 5 and 7 are shown in cross section), 8 is a relatively low precision first temperature control device, and 9 is the first temperature control device 8.
This is a second temperature control device with higher precision.

In this embodiment, the temperature of the radiator 1 is strictly controlled to a predetermined temperature by a highly accurate second temperature controller 9, and the temperature of the inner wall 2 is controlled by a relatively inexpensive and low accurate first temperature controller. The temperature control device 8 is configured to control the temperature within a substantially predetermined temperature range.

Note that the shape and size of the cavity of the blackbody furnace may be any suitable shape and size.

[Brief explanation of drawings]

The drawing is a sectional view showing an embodiment of a blackbody furnace according to the present invention. 1... Radiator made of a material with high emissivity, 2... Inner wall formed of a material with low emissivity, 3... Small hole, 4, 6... Thermocouple, 5, 7...
Heating conductor, 8...first temperature control device, 9...second temperature control device.

Claims (1)

[Claims] 1 The temperature of the inner wall of the blackbody furnace is controlled by configuring the inner wall of the blackbody furnace with a material with low emissivity, and installing a radiator made of a material with a high surface emissivity in the cavity of the blackbody furnace. A blackbody furnace comprising: a first temperature control device; and a second temperature control device that controls the temperature of the radiator and is more accurate than the first temperature control device.