JPS63117226A - Infrared ray detector - Google Patents

Abstract

PURPOSE:To dispense with a cold shield and to shorten the time required in cooling, by setting a spherical infrared ray reflecting member having an opening part introducing infrared rays to be measured to that the center of the curvature thereof is positioned in the vicinity of a detection element. CONSTITUTION:A spherical infrared ray reflecting member 8 has a Dewar window 2 for introducing infrared rays 7 to be measured. Since the unnecessary infrared rays 9 incident from the circumferential background of Dewar 1 is blocked by the reflecting member 8, the increase in noise can be suppressed. Since a detection element 3 is positioned in the vicinity of the center of the curvature of the reflecting member 8, the image due to the reflection of the reflecting member 8 is generated on the element 3 and the mount substrate 6 in the vicinity thereof. Therefore, only the unnecessary infrared rays 10 emitted from the element 3 and from the vicinity thereof are incident to the element 3 by the reflection of the reflecting member 8 and unnecessary infrared rays from other part are not incident thereto. Moreover, since the radiation quantity of infrared rays from the element 3 and the substrate 6 is sufficiently little, the increase in noise can be suppressed. By this constitution, since this detector has the same noise reducing action as the case using a cold shield and the cold shield becomes unnecessary, a cooling time can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an infrared detector used, for example, in an infrared imaging device.

[Prior Art] FIG. 3 shows, for example, the environmental research institute in Michigan.
talResaach In5titude of M
Id, L, lN0LFE, G, J, ZISSIS, published in 1978 by
) r Infrared Handbook J (The Infrare
d) is a sectional view of a conventional infrared detector shown in pages 15 to 18 of Handbook. In the figure, (1) is a container made of double walls.

Hereinafter, this will be referred to as Dewar. (2) is a dewar window, (3) is a quantum infrared detection element (hereinafter referred to as the detection element), (4) is a cold shield, (5)
) is a container filled with refrigerant, and (6) is the detection element (3).
) is attached to the board, and (7) is the infrared ray to be measured. Note that the container (5) is cooled by a refrigerant injected into it, thereby increasing the detection sensitivity of the detection element (3). Also, the cold shield (4) is attached to the board (
6) and cooled in the same manner as the detection element (3) described above. The space between the walls of the dewar (1) is evacuated to efficiently cool the detection element (3) and cold shield (4), and the wall surface facing the vacuum is designed to reflect heat rays. has been done.

A conventional infrared detector is constructed as described above, and the infrared rays to be measured (7) are incident on the detection element (3) through the dewar window (2) and the opening of the cold shield (4).
This is detected. Here, the cold shield (4
) prevents unnecessary infrared rays emitted from the ambient background at room temperature from entering the detection element (3).
) to reduce noise. Therefore, the cold shield (4) has a high surface emissivity and is cooled to a low temperature.
The amount of unnecessary infrared radiation emitted from the surface of ) is reduced to a negligible level compared to the infrared radiation to be measured (7).

[Problems to be Solved by the Invention] In the conventional infrared detector as described above, it was necessary to cool not only the detection element but also the cold shield in order to reduce noise. This increases the thermal load on the refrigerant, resulting in a problem that the time required to cool the detection element and the cold shield to a predetermined temperature increases. Infrared detectors used in infrared guided missiles in particular need to be cooled down to a predetermined temperature within a few seconds, and the long time it takes to cool them down is a fatal problem.

This invention was made to solve these problems, and it is possible to omit the cold shield and significantly shorten the time required for cooling while maintaining the same noise reduction effect as when using the cold shield. With the goal.

[Means for Solving the Problems] The infrared detector according to the present invention includes a spherical infrared reflecting member having an opening for introducing infrared rays to be measured so that its center of curvature is located near the detection element. It is set to .

[Function] In this invention, only a small amount of infrared rays reflected by the infrared reflecting member and incident on the detection element is emitted from the detection element and its vicinity, and unnecessary infrared rays from other parts are not incident on the detection element. Therefore, it has the same noise reduction effect as using a cold shield. Furthermore, since a cold shield is not required, the time required for cooling is shortened.

[Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention, and (1
) to (3) and (5) to (7) are substantially the same elements as those of the conventional device shown in FIG. 3 above. (8) is an infrared reflecting member, and (9) and (10) are unnecessary infrared rays. Here, the infrared reflecting member (8) has a spherical shape, and a dewar window (2) for introducing the infrared ray to be measured (7).
). Of course, the infrared reflecting member (8) is mounted on the substrate (6) so that its center of curvature is located near the detecting element (3).

In the infrared detector configured as above, unnecessary infrared rays (9) incident from the background surrounding the dewar (1)
Since the infrared rays are blocked by the infrared reflecting member (8), an increase in noise can be suppressed. Next, the influence of unnecessary infrared rays (10) radiated from inside the dewar (1) will be explained. First, since the detection element (3) is located near the center of curvature of the detection line reflecting member (8), the image of the detection element (3) due to reflection by the infrared reflection member (8) is the same as that of the detection element (3) and Mounting in its vicinity occurs on the substrate (6). This means that the detection element (3)
This means that only unnecessary infrared rays (10) emitted from the vicinity thereof enter the detection element (3) by reflection by the infrared reflecting member (8), and unnecessary reflected infrared rays from other sources do not enter. Moreover, since the amount of infrared radiation from the substrate (6) in these detection elements (3) and their mounting is sufficiently small, an increase in noise can be suppressed.

Here, since the emissivity of the infrared reflecting member (8) is small, the amount of unnecessary infrared radiation from the infrared reflecting member (8) itself is small, and the increase in noise due to this influence can be ignored. In addition, when mounting near the detection element (3), if a high reflectivity part such as an electrode is provided on the substrate (6), the dewar (1)
Dewars unnecessary infrared rays emitted from normal temperature parts inside and outside (
1) Due to multiple reflections within the infrared reflecting member (
8) and may enter the detection element (3).

In this case, the effect can be removed by covering the electrodes and the like in the highly reflective portions with an insulating infrared absorbing layer such as paint.

FIG. 2 is a sectional view showing another embodiment of the present invention. The dewar window (2) has a spherical shape, and the inner surface of the dewar window (2) is covered with an infrared reflecting member (8), leaving an opening for introducing the infrared rays (7) to be measured.

Note that the center of curvature of the infrared reflecting member (8) is located at the detection element (3).
), the same operation as in the first embodiment can be achieved.

Although the above explanation deals with the case where the inner surface of the dewar window (2) is covered with the infrared reflecting member (8), the same effect can be obtained even if the outer surface of the dewar window (2) is covered with the infrared reflecting member (8). perform the following actions. However, in this case, the infrared reflective member (
Since unnecessary infrared rays emitted from the inner surface of the dewar window (2) itself in the portion covered by 8) is added to the noise source, the noise increases accordingly. However, since the emissivity of the dewar window (2) is small, the increase in noise is small and poses no problem in practice.

[Effects of the Invention] As explained above, this invention achieves the same noise reduction as a cold shield through a simple structure of attaching a spherical infrared reflecting member.

A cold shield is not required, which greatly reduces the time required for cooling.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the invention, and FIG. 3 is a sectional view showing a conventional infrared detector. In the figure, (1) is a dewar window, (2) is a dewar window, and (3) is a dewar window.
(5) is a refrigerant container (cooling means), (6) is mounted on a board, (7) is an infrared ray to be measured, (
8) is an infrared reflecting member, and (9) and (10) are unnecessary infrared rays. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In an infrared detector equipped with a dewar having a dewar window whose interior is in a vacuum state, a quantum infrared detection element installed inside the dewar, and cooling means for the quantum infrared detection element, The quantum infrared detector includes a spherical infrared reflecting member having an opening for introducing measurement infrared rays into the quantum infrared detecting element, and the center of curvature of the infrared reflecting member is located near the quantum infrared detecting element. An infrared detector characterized in that the is installed on a substrate. (2) The infrared detector according to claim 1, characterized in that a high reflectance portion in the vicinity of the substrate to which the quantum infrared detecting element is attached is coated with an insulating infrared absorbing layer.