JPH04369439A - Black body - Google Patents

Abstract

PURPOSE:To obtain a calibration black body with emissivity improved by providing a groove whose depth size is several times its widthwise size between adjacent pyramids. CONSTITUTION:A calibration black body 30 has grooves 31 at positions between adjacent pyramids 21, that is at portions of recesses 23, while the grooves 31 are, when viewed from above, formed in a grid in X-and Y-directions. The groove 31 is 0.1 to 0.2mm in width and 0.5 to 1.0mm in depth which is approximately five times the width. Infrared rays 22-1 incident to a slope of the pyramid 21 are reflected three times while infrared rays 22-2 incident between the adjacent pyramids 21 enter the groove 31. Since the groove 31 is narrow and deep, the infrared rays 22-2 are reflected on one of sides 31b before reaching the bottom 31a then reflected on the bottom 31a, further reflected on the other side 31c, and then returned out of the groove 31. Therefore the calibration black body 30 has improved in emissivity as regards portions between the adjacent pyramids 21 thereby providing high emissivity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black body for calibrating an infrared detection device.

FIG. 19 shows an infrared detection device 1 to which the calibration black body of the present invention is applied.

Reference numeral 2 denotes an infrared detector, which detects infrared rays 4 emitted from a subject 3.

[0004] The output from the infrared detector 2 is calculated in a calculation section 5 and is made into a signal indicating the temperature of the subject 3, and an image indicating the temperature of the subject 3 is displayed on the display section 6.

Reference numeral 10 denotes a calibration blackbody for calibrating the infrared detector 2, which is incorporated into the infrared detector 1.

A heater 11 heats the calibration black body 10 to a predetermined temperature during calibration.

[0007] Calibration is carried out periodically by heating the calibration blackbody 10 to a predetermined temperature using the heater 11, and at this time, infrared rays 12 emitted from the calibration blackbody 10 are made to enter the infrared detector 2. This is done by re-memorizing the output of the infrared detector 2 in place of what was previously stored.

First, it is desirable that the calibration black body 10 ideally have an emissivity of "1" in order to accurately display the temperature of the subject 3.

Secondly, since the infrared detection device 1 is mounted on an aircraft or an artificial satellite, it is desirable that the calibration black body 10 be lightweight.

The emissivity of the black body 10 described above will now be explained.

The smaller the ratio of the infrared rays to the incident infrared rays relative to the black body 10, the greater the absorption rate.

According to Kirchhoff's law, there is a relationship that the higher the absorption rate, the higher the emissivity.

Therefore, from now on, for convenience of explanation, the absorption rate will be explained.

The effective emissivity ε of the black body 10 is

[0015]

[Math 1]

It is represented by:

Here, ε0 is the intrinsic reflectance of the surface of the black body 10.

Rn is the rate at which infrared rays are reflected n times from the time they are incident until they return;

[0019]

[Math 2]

When ε0 is approximately 1, even after several reflections,
The effective reflectance becomes very large.

[0021]

2. Description of the Related Art FIG. 20 shows a conventional black body 20 for calibration. This calibration blackbody 20 is made by cutting an aluminum disc as a base material using a cutting tool, and has a large number of square pyramids 21 adjacent to each other and aligned in the X and Y axis directions on the surface. are doing.

[0022] In addition, it has been subjected to black oxidation treatment, and the surface is
It is black.

Of the infrared rays incident on the black body 20, code 2
As shown by 2, infrared rays that are perpendicularly incident on the black body 20 are generally considered to have a small number of reflections.

Therefore, from now on, we will consider the infrared rays 22 that are incident perpendicularly to the black body 20.

As shown in FIG. 21, the infrared rays 22-1 incident on the slope 21a of the quadrangular pyramid 21 return from the black body 20, having been reflected at least three times (■-■). The numbers enclosed in circles indicate the number of reflections.

Furthermore, the portion of the black body 20 between the adjacent quadrangular pyramids 21, that is, the bottom portion of the X-shape, is not a perfect acute angle because it is cut using a cutting tool. As shown in an enlarged view in FIG. 21, it has a rounded and smooth concave surface 23.

[0027]

[Problem to be Solved by the Invention] Therefore, the infrared rays directly incident on the concave surface 23 as shown by the reference numeral 22 are reflected only once by the concave surface 23, and the infrared rays are reflected from the calibration black body as shown by the reference numeral 26. It goes back from 20.

As described above, the conventional black body 20 has a low absorption rate in the area between the adjacent square pyramid parts 21 on the entire surface.
The emissivity of the calibration black body 20 is correspondingly lower.

An object of the present invention is to provide a black body for calibration with improved emissivity.

[0030]

[Means for Solving the Problems] The invention of claim 1 provides a black body whose surface has a shape in which a large number of pyramidal parts are arranged adjacent to each other. This is a calibration with a groove that is several times the size.

[0031] According to a second aspect of the invention, the surface has a lattice portion forming a large number of polygonal holes, and the bottom of each hole is formed as a pyramid portion.

According to the third aspect of the invention, the surface has a grid portion forming a large number of polygonal holes, and the bottom of each hole is formed as a rough surface.

[0033] The invention according to claim 4 has a lattice portion forming a large number of polygonal holes on the surface, and the bottom of each hole is
It is configured as a pyramidal recess.

[0034] The invention according to claim 5 has a lattice portion forming a large number of polygonal holes on the surface, and the bottom of each hole is
The recess is formed into a pyramidal recess, and a hole whose depth is several times the diameter in the radial direction is provided in the center of the recess.

According to a sixth aspect of the present invention, in the fifth aspect, the bottom of the hole is made rough.

[0036] According to a seventh aspect of the invention, the lattice portion according to any one of claims 2 to 5 has a roof-shaped portion on an end face.

[0037] According to an eighth aspect of the present invention, the lattice portions according to any of claims 2 to 5 are formed by walls having the same thickness throughout.

[0038]

The groove of the first aspect functions to increase the number of reflections of infrared rays incident between adjacent pyramid parts.

[0039] The holes in the lattice portion according to claims 2 to 5 function so that the inner wall surface thereof increases the number of reflections of infrared rays.

The pyramidal portion of the second aspect works in cooperation with the inner wall surface of the hole to increase the number of reflections of infrared rays. The rough surface of the third aspect functions to diffusely reflect infrared rays that reach the bottom of the hole. The pyramidal concave portion of the present invention functions to reflect infrared rays toward the inner wall surface of the hole.

The hole according to the fifth aspect functions to increase the number of reflections of infrared rays incident on the center of the hole. The rough surface of the present invention acts to diffusely reflect infrared rays that reach the bottom of the hole. The roof-shaped portion of the seventh aspect functions to reflect infrared rays incident on the end face of the lattice portion toward the inside of the hole.

[0042] The wall body having the same thickness throughout serves to reduce the weight of the black body.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a black body 30 according to a first embodiment of the present invention. Components corresponding to those shown in FIGS. 20 and 21 are given the same reference numerals.

This black body 30 has a structure in which a groove 31 is provided at a position between adjacent quadrangular pyramids 21, that is, at a portion of the concave surface 23 in the conventional example. The grooves 31 are formed in a grid pattern in the X and Y directions when viewed from the top surface of the black body 30. Further, the groove 31 has a width dimension a of 0, as shown in an enlarged view in FIG.
．． 1 to 0.2 mm, and the depth dimension b is 0.5 to 1.0
mm, which is about 5 times the width dimension a.

[0045] Not only the surface of the quadrangular pyramid portion 21 but also the inner surface of the groove 31 is subjected to blackening treatment.

Next, the state of reflection of infrared rays incident perpendicularly to the calibration black body 30 will be explained.

The infrared rays 22-1 incident on the slope 21a of the quadrangular pyramid 21 are reflected three times as in the conventional case, as shown in FIG.

The infrared rays 22-2 that have entered between the adjacent quadrangular pyramids 21 enter into the grooves 31, as shown in FIG.

Here, since the groove 31 is narrow and deep, the infrared rays 22-2 are reflected from one side surface 31b and then reflected from the bottom surface 31a before reaching the bottom surface 31a of the groove 31. , further reflected by another side surface 31c, and then the groove 31
Get out of the black body 30 and go back.

That is, the infrared ray 22-2 is reflected three times, and the number of reflections is two more than in the conventional case.

Therefore, the above-mentioned calibration black body 30 has improved emissivity in the portion between the adjacent quadrangular pyramids 21, and has a higher emissivity than the conventional one.

The blackbody may have a structure in which triangular pyramids are arranged adjacent to each other and a groove is formed between the adjacent triangular pyramids.

FIGS. 4 to 6 show a black body 40 according to a second embodiment of the present invention.

41 is a rectangular lattice portion, and the wall body 42
extends in the X and Y directions, and is formed on the surface of the black body 40.

The thickness t of the wall body 42 is approximately 0.3 mm,
Equal throughout.

[0056] The dimension c between adjacent wall bodies 42 is 5 mm. The height dimension d of the wall body 42 is 25 to 30 mm,
This is approximately five times the dimension c above.

This lattice portion 41 has a square cross section with a side length of 5 mm, and a depth equal to 5 mm of the side length.
It has a configuration in which a large number of prismatic holes 43, which are 6 times as deep, are arranged adjacent to each other.

Each hole 43 has a square pyramid portion 44 at its bottom.

Further, the upper surface of the lattice portion 42, that is, the upper end of the wall body 42 is a roof-shaped portion 44 having a triangular cross section.
It does not have a plane parallel to the Y plane.

Furthermore, the entire black body 40 has been subjected to a blackening process.

The black body 40 is manufactured by electrical discharge machining of an aluminum base material.

Next, the emissivity of the black body 40 having the above structure will be explained.

In FIG. 7, infrared rays 2 obliquely incident on the black body 40
2-3 enters the hole 43, repeats multiple reflections on the inner wall surface 43a of the hole 43, and heads toward the bottom. The light is repeatedly reflected between the holes 43, and then moves upward, and after being reflected multiple times on the inner wall surface 43a of the hole 43, it escapes upward.

Infrared rays 22-4 incident perpendicularly on the black body 40
As shown in FIG. 7, the light reaches the bottom of the hole 43 without being reflected by the inner wall surface 43a of the hole 43, is reflected by the slope 44 of the quadrangular pyramid 44, and is directed toward the inner wall surface 43a near the bottom of the hole 43. . The light is reflected multiple times between the inner wall surface 43a and the slope 44a and heads toward the bottom. Thereafter, the light heads upward, is reflected on the inner wall surface 43a, and escapes upward.

Infrared rays 22 incident on the upper end surface of the grating section 41
-5 is reflected by the slope 45a of the roof-shaped portion 45 and enters the hole 43, as also shown in FIG. After that, hole 43
After being reflected multiple times on the inner wall surface 43a of the square pyramid section 44 and the slope 44a of the square pyramid section 44, it escapes upward.

As can be seen from the above, the number of reflections of infrared rays is large, and the black body 40 has a higher emissivity than the black body 40 of the first embodiment.

Next, the weight of the black body 40 having the above structure will be explained.

The thickness t of the wall 42 of the lattice portion 41 is the same in the thickness direction.

Therefore, the calibration black body 40 is lighter than a structure in which the wall body 42 is thicker on the base side.

FIGS. 8 and 9 show a black body 50 according to a third embodiment of the present invention. In each figure, parts corresponding to those shown in FIGS. 4 and 6 are given the same reference numerals. 51 is the flat bottom of the hole 43, and its surface is a rough surface 52.

Infrared rays 22-6 perpendicularly incident on the black body 40
As shown in FIG. 9, the light reaches the bottom 51 of the hole 43, where it is diffusely reflected, reflected multiple times on the inner wall surface 43a, and exits upward.

FIGS. 10 to 12 show a black body 60 according to a fourth embodiment of the present invention.

In each figure, parts corresponding to those shown in FIGS. 4 to 6 are given the same reference numerals.

Reference numeral 61 is a quadrangular pyramid-shaped recess, which constitutes the bottom of the hole 43.

Infrared rays 2 incident perpendicularly on the calibration black body 60
2-7 reaches the bottom of the hole 43, as shown in FIG.
It has a quadrangular pyramid shape and is reflected multiple times on the slope 61a of the recess 61, then reflected multiple times on the inner wall surface 43a, and exits upward.

FIGS. 13 and 14 show a calibration black body 70 according to a fifth embodiment of the present invention.

In each figure, parts corresponding to those shown in FIGS. 10 to 12 are given the same reference numerals.

71 is a small hole with a diameter e of approximately 0.3 m.
m and depth f of approximately 1.0 mm, and is formed at the center of the quadrangular pyramidal recess 61.

The infrared rays 22-8 that are perpendicular to the black body 70 and incident on the center of the hole 43 are transmitted through the small hole 71 as shown in FIG.
It is reflected multiple times on the peripheral wall surface 71a and bottom surface 71b of the small hole 7.
1, is reflected multiple times on the inner wall surface 43a of the hole 43, and then escapes from the hole 43. 15 and 16 show a black body 80 according to a sixth embodiment of the present invention.

In each figure, parts corresponding to those shown in FIGS. 13 and 14 are given the same reference numerals.

The bottom portion 71c of the small hole 71 has a rough surface 71d.

The infrared rays 22-9 incident perpendicularly to the black body 80 and at the center of the hole 43 are reflected by the peripheral wall surface 71a of the small hole 71 and reflected by the rough surface 71d of the bottom portion 71c, as shown in FIG.
The light is diffusely reflected by the peripheral wall surface 71a and exits from the small hole 71, and is reflected multiple times by the inner wall surface 43a of the hole 43 and exits from the hole 43.

FIG. 17 shows a blackbody 90 according to a seventh embodiment of the present invention.

The lattice portion 91 has a structure in which triangular prism-shaped holes 92 are formed.

[0085] At the bottom of each hole 92, a triangular pyramid part or a triangular pyramid-shaped concave part is formed.

FIG. 18 shows a black body 100 according to the eighth embodiment of the present invention.
shows.

[0087] The lattice portion 101 has a structure in which holes 102 are formed in the shape of a hexagonal column.

A hexagonal pyramid or a hexagonal pyramid-shaped recess is formed at the bottom of each hole 102.

[0089]

As explained above, according to the invention of claim 1, it is possible to improve the emissivity compared to the conventional one.

According to the second aspect of the invention, it is possible to improve the emissivity compared to the first aspect of the invention.

According to the third aspect of the invention, it is possible to improve the emissivity compared to the first aspect of the invention.

According to the fourth aspect of the invention, it is possible to improve the emissivity compared to the first aspect of the invention.

According to the invention of claim 5, the emissivity can be improved compared to the invention of claim 4.

According to the invention of claim 6, it is possible to improve the emissivity compared to the invention of claim 5.

According to the seventh aspect of the invention, it is possible to improve the emissivity of the end face of the grating portion as well.

According to the invention of claim 8, weight reduction can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a black body according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II in FIG. 1.

FIG. 3 is a diagram showing the state of reflection of infrared rays within the groove in FIGS. 1 and 2;

FIG. 4 is a perspective view of a blackbody according to a second embodiment of the present invention.

FIG. 5 is a plan view of a portion of the black body of FIG. 4;

6 is an enlarged sectional view taken along the line VI-VI in FIG. 4. FIG.

FIG. 7 is a diagram showing the state of reflection of infrared rays.

FIG. 8 is a perspective view of a blackbody according to a third embodiment of the present invention.

9 is a sectional view taken along line IX-IX in FIG. 8. FIG.

FIG. 10 is a perspective view of a blackbody according to a fourth embodiment of the present invention.

FIG. 11 is a partial plan view of the blackbody in FIG. 10;

12 is a sectional view taken along line XII-XII in FIG. 10. FIG.

FIG. 13 is a plan view of a part of a calibration blackbody according to a fifth embodiment of the present invention.

14 is an enlarged sectional view taken along line XII-XII in FIG. 13. FIG.

FIG. 15 is a plan view of a part of a blackbody according to a sixth embodiment of the present invention.

16 is an enlarged sectional view taken along line XVI-XVI in FIG. 15. FIG.

FIG. 17 is a perspective view of a blackbody according to a seventh embodiment of the present invention.

FIG. 18 is a perspective view of a blackbody according to an eighth embodiment of the present invention.

FIG. 19 is a block diagram of an infrared detection device equipped with a calibration black body.

FIG. 20 is a perspective view of an example of a conventional black body.

21 is an enlarged sectional view taken along line XXI-XXI in FIG. 20. FIG.

[Explanation of symbols]

21 Square pyramid part 22-1 to 22-8 Infrared rays 30, 40, 50, 60, 70, 80, 90, 100
Black bodies 41, 91, 101 Lattice section 42 Wall body 43 Prismatic hole 43a Inner wall surface 44 Square pyramid section 44a Slope 45 Roof section 51 Bottom section 52 Rough surface 61 Square pyramid recess 61a Slope 71 Small hole 71a Peripheral wall surface 71b Bottom surface 71c Bottom 71d Rough surface 92 Triangular prism-shaped hole 102 Hexagonal prism-shaped hole

Claims (8)

[Claims] 1. In a black body whose surface has a shape in which a large number of pyramidal parts (21) are arranged adjacent to each other, a groove (21) whose depth dimension is several times the width dimension is formed between the adjacent pyramidal parts. 31)
A black body characterized by having a configuration in which . 2. The surface has a lattice part (41) forming a large number of polygonal holes (43), and the bottom of each hole is
A black body characterized by having a configuration as a pyramidal part (44). 3. A lattice part (41) forming a large number of polygonal holes (43) on the surface, and a bottom part (5) of each hole.
A black body characterized in that 1) is configured as a rough surface (52). Claim 4: A large number of polygonal holes (43) on the surface.
A blackbody characterized in that it has a lattice part (41) forming a lattice part, and the bottom of each hole is formed as a pyramidal recess part (61). [Claim 5] A large number of polygonal holes (43) on the surface.
, and the bottom of each hole is a pyramidal recess (61).
1), a hole (71
). 6. The blackbody according to claim 5, wherein the bottom (71c) of the hole (71) is a rough surface (71d). 7. The lattice portion (41) according to claims 2 to 5 includes:
A black body characterized by having a roof-shaped portion (45) on an end surface. 8. A calibration black body according to claim 2, wherein the grid portion is formed by a wall body (42) having an equal thickness throughout.