JP3025353B2 - Black body emissivity standard - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a blackbody emissivity standard. A black body is generally an object that completely absorbs all incident radiation, regardless of its wavelength, direction of incidence, or state of polarization, and which also has a given temperature for any wavelength. Is the ideal temperature radiator with the highest spectral radiance, and is also referred to as a perfect radiator.

[0002] Since blackbody radiation is uniquely determined by determining the temperature of the blackbody, the blackbody is extremely useful as a temperature reference (reference light source) in the construction of infrared application equipment and the like. The ideal emissivity of a black body is equal to 1, but it is not practically possible to achieve this, and if a black body is used as a temperature reference, its emissivity must be accurately measured. There is.

[0003]

2. Description of the Related Art Conventionally, in order to measure the emissivity of a black body under test, the radiation power from a black body (black body emissivity standard), which is a reference whose emissivity is known, and the black body under test are measured. Was measured indirectly by measuring the radiated power from a radiometer and comparing the measured values.

[0004]

In the conventional black body emissivity standard, since the emissivity is constant, the emissivity of the black body to be tested is indirectly obtained by performing the comparative measurement as described above. I could only ask for it. Assuming that a black body emissivity standard that can directly read the emissivity of the test black body is realized,
It is extremely useful for measuring the emissivity of the black body under test.

The present invention has been made in view of such circumstances, and has as its object to provide a black body emissivity standard which enables direct measurement of the emissivity of a black body to be tested.

[0006]

According to the present invention, there is provided a blackbody emissivity reference device comprising: a base portion; and a plurality of parallel parallel projecting members projecting obliquely from the base portion and capable of adjusting an angle between the base portion and the base portion. A black body comprising a fin, a means for detecting an angle formed by the fin and the base, and a means for displaying a predetermined black body emissivity according to the detected angle. Be composed.

[0007]

According to the present invention, since a black body including a base and a plurality of fins which are obliquely projecting from the base and are parallel to each other is used, the light is reflected on the surfaces of the base and the fin. Is likely to occur many times, and a high emissivity (emissivity close to 1) can be accurately measured.

In addition, in this black body, an angle between the base and the fin can be adjusted, and a means for displaying a predetermined black body emissivity according to the angle is provided. The emissivity of the black body under test can be directly read with the display emissivity when the radiation power from the black body of the black body emissivity standard becomes equal to the radiation power from the black body under test.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a blackbody emissivity standard showing an embodiment of the present invention. A black body 2, which is a component of the reference device, includes a base 4 and an obliquely projecting base 4 protruding from the base 4.
Parallel to each other (in the figure, 3
(Only one is shown).

The fin portion 6 is rotatably supported by a fin holding portion 8 provided in parallel with the base portion 4. One end of the fin portion 6 has a recess formed on the base portion 4. 4a is loosely fitted. At the other end of the fin 6, a connecting bar 10 parallel to the base 4 is pivotally supported.
Of the fin 6 by moving the
The angle between each of the fins 6 and the base 4 parallel to each other can be adjusted within a range in which one end of the fin 6 is within the recess 4a.

The amount of movement of the connecting portion 10 is detected by a movement amount detector 14 constituted by using an electromagnetic scale or the like, and this movement amount is determined by a predetermined conversion function.
At 6, the angle is converted to the angle between the fin 6 and the base 4. The angle is converted into an emissivity in the emissivity converter 22 based on a predetermined conversion function, and the emissivity is displayed by the emissivity display 24.

A voltage signal corresponding to the angle from the angle converter 16 is input to a minus input port of the operational amplifier 20, and a voltage signal from the variable power supply 18 is input to a plus input port of the operational amplifier 20. . Then, the output port of the operational amplifier 20 is input to the drive unit 12 of the coupling unit 10, whereby the coupling unit 10 is driven such that the output signal from the operational amplifier 20 becomes zero or constant.

According to this configuration, the angle between the fin portion 6 and the base portion 4 can be arbitrarily set by changing the variable power supply 18. In this example, the angle between the fin 6 and the base 4 is obtained based on the amount of movement of the connecting portion 10. However, by providing an appropriate angle sensor for the fin 6,
The angle between the fin and the base may be directly measured.

In measuring the emissivity of the black body under test using the black body emissivity standard, the radiation power of the black body under test and the radiation power of the black body 2 of this standard are measured. , Adjust the variable power supply 18 so that these measurements match,
The display content of the emissivity display 24 at that time is read. Thereby, the emissivity of the test black body can be directly measured.

FIG. 2 is a perspective view of a black body showing an embodiment in which the base is formed in a disk shape, and FIG. 3 is a partial side view of the black body. In this embodiment, a columnar base 6a is integrally formed at one end of a plate-like fin 6, and the base 6a is formed in a groove formed on the base 4 corresponding to the shape of the base 6a. Are fitted from the side. The tip 6b of the fin 6 is formed in a tapered shape.
0 is provided. By forming the tip of the fin portion in a tapered shape, a high emissivity can be obtained.

In this example, the fin 6 is assembled from the side of the base 4 so as to fit into the groove thereof, so that the disk-shaped base 4 can be employed. A black body having a disk-shaped base is convenient for optical measurement.

FIG. 4 shows the angle between the fin 6 and the base 4 with respect to the fin 6 when the black body emissivity standard of this embodiment is used for measuring the emissivity of the black body to be tested. FIG. 5 is a ray tracing diagram when light is incident on the larger side, and FIG. 5 is a ray tracing when infrared rays are incident on the smaller angle between the fin 6 and the base 4 with respect to the fin 6. FIG.

In both the case where the light is incident in a direction perpendicular to the base 6 and the case where it is inclined by ± 5 ° with respect to this direction, the incident infrared light is reflected many times on the surface of the fin 6 or the surface of the base 4. You can see how it is. As described above, according to the present embodiment, since the incident infrared light is reflected many times, this black body 2 is reflected.
Is suitable for measuring a blackbody emissivity close to 1.

The setting of each shape parameter when varying the emissivity of the black body emissivity standard in this embodiment will be described below. Generally, the apparent emissivity (effective emissivity) ε of an opaque body having irregularities on its surface is given by the following equation.

[0020]

(Equation 1)

Here, R _n is a rate at which the reflection is repeated n (natural number) times from when the infrared ray enters the black body until the infrared ray exits, and ε ₀ is the intrinsic emissivity of the object surface. Note that R _n satisfies the following expression.

[0022]

(Equation 2)

In the equation (1), when ε ₀ is large, the term where n> 1 is small on the right side, and under the condition of R ₁ ≠ 0, ε mainly depends on R ₁ and ε ₀ . Therefore,
Equation (1) can be approximated as follows.

[0024]

(Equation 3)

FIG. 6 is a graph showing the relationship between the effective emissivity ε and the single reflection ratio R ₁ based on the equation (3). In order to make the effective emissivity variable, the ratio R _{1 of} single reflection may be made variable.

In order to increase the effective emissivity ε, the specific emissivity ε ₀ may be increased or the ratio R ₁ of one-time reflection may be reduced. In order to increase the specific emissivity ε ₀ , black oxidation treatment or black coating is effective. Consider the relationship between the shape parameters that is desirable for reducing the _single reflection ratio R ₁ .

When the diameter D of the black body is less than 10 cm, the calibration accuracy of the black body deteriorates. When the diameter D is more than 40 cm, the total weight of the black body emissivity standard becomes too large.
It is desirable to be in the range of 40 cm. In this embodiment, D
= 30 cm.

A desirable range of the inclination angle θ of the fin will be described. Note that for convenience of explanation, it is assumed that H / L = x. Here, H is the height of the fin, and L is the interval between the fins. FIG.
FIG. 4 is an explanatory diagram of a single reflection when 0 ° <θ <45 °.
In this case, assuming that a range in which the light can be reflected once on the surface of the fin portion 6 (the length on the base portion 4) is w, the ratio R1 of the _single reflection is given by the following equation.

[0029]

(Equation 4)

FIG. 8 is an explanatory diagram of one-time reflection when 45 ° ≦ θ <90 °. In this case, assuming that a range in which the light is reflected once on the surface of the base portion 4 is w, the ratio R _{1 of the} single reflection is given by the following equation.

[0031]

(Equation 5)

FIG. 9 is a graph based on equations (4) and (5).
9 is a graph showing a relationship between the ratio R _{1 of the} round reflection and the inclination angle θ of the fin 6. In order to obtain a variable effective emissivity, the range in which the inclination angle θ of the fin 6 should satisfy is as follows.

When x = 1, 0 ° <θ <45 °
Or 45 ° <θ <90 °. When x = 2, 0 ° <θ <45 ° or 63 ° <
θ <90 °. When x = 3, 0 ° <θ <45 ° or 72 ° <
θ <90 °.

When x = 4, 0 ° <θ <45 °
Or 46 ° <θ <90 °. When x = 5, 0 ° <θ <45 ° or 79 ° <
θ <90 °.

[0035]

As described above, according to the present invention,
This has the effect of providing a blackbody emissivity standard that allows direct measurement of the blackbody emissivity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a blackbody emissivity standard according to an embodiment of the present invention.

FIG. 2 is a perspective view showing another configuration example of the black body in the black body emissivity standard device.

FIG. 3 is a partial side view of the black body of FIG. 2;

FIG. 4 is a ray tracing diagram (part 1) in the embodiment of the present invention.
It is.

FIG. 5 is a ray tracing diagram (part 2) according to the embodiment of the present invention.
It is.

FIG. 6 is a graph showing the relationship between the effective emissivity and the ratio of single reflection.

FIG. 7 is an explanatory diagram of single reflection when 0 ° <θ <45 °;

FIG. 8 is an explanatory diagram of one-time reflection when 45 ° ≦ θ <90 °.

FIG. 9 is a graph showing the relationship between the ratio of single reflection and the inclination angle.

[Explanation of symbols]

 2 Black body 4 Base 6 Fin

Continuation of the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01J 5/00-5/62 JICST file (JOIS)

Claims (1)

(57) [Claims] A black body comprising: a base portion (4); and a plurality of parallel fins (6) projecting obliquely from the base portion and adjusting an angle between the base portion and the base portion. A black body emissivity, comprising: means for detecting an angle formed by the fin and the base; and means for displaying a predetermined black body emissivity according to the detected angle. Reference device.