JPH0629698Y2 - Infrared detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention uses, for example, an infrared detection element mounted in an infrared imaging device and used by cooling at a cryogenic temperature of, for example, about 80 K such as HgCdTe or InSb. Regarding infrared detectors.

[Conventional technology]

FIG. 2 is a diagram showing a conventional infrared detector, which is generally divided into a dewar (2) having an infrared detecting element (1) built-in and the infrared detecting element (1) at an extremely low temperature, for example, 8
It is composed of a refrigerator (3) for cooling around 0K.
As the refrigerator (3), a Stirling cycle, a Gifode McMahon cycle, or a refrigerator utilizing the Joule-Thomson effect is often used, and FIG. 2 shows a refrigerator utilizing the Stirling cycle as an example. The refrigerator (3) is composed of the compressor of (4), the low temperature generating part of (5) and the connecting pipe of (6), and the low temperature generating part (6) is called a cold finger (7). An elongated cylindrical protrusion is provided, and the structure is such that freezing is generated at the tip of the cold finger (7).

The dewar (2) is for accommodating the infrared detecting element (1) while keeping it insulated at a cryogenic temperature, and includes an outer shell (8),
Infrared transparent window (9) attached to the outer shell (8)
An inner shell cylinder (10) whose one end is attached to the outer shell (8) and is surrounded by the outer shell (8), and the inner shell cylinder (10) is provided at another end of the inner shell cylinder (10) and The infrared detecting element (1) is composed of an inner shell bottom plate (11) holding the infrared detecting element (1).
The inside has a vacuum shell structure so that heat cannot enter from the outside, and the inner shell cylinder (10) is made of a material having a small thermal conductivity such as glass. Also, the inner shell bottom plate
A cold shield (11) is provided to cover the side of the infrared detecting element (1) to prevent infrared rays other than those passing through the window (9) from entering the infrared detecting element (1). 1
2) is installed.

(13) is a thermal interface, and the thermal interface (13) is attached to the tip of the cold finger (7) and is made of the cold finger (7) which is generally made of metal and glass. The inner shell cylinder that is (10)
It is for absorbing the difference in heat expansion between the inner and outer shells. For example, a material with elasticity and large thermal conductivity, such as laminated copper foil, is used, and its tip is always in close contact with the inner shell bottom plate (11). It is about to do.

Next, the operation of the conventional device shown in FIG. 2 will be described. When the refrigerator (3) starts to operate and starts to generate refrigeration at the cold finger (7) tip of the low temperature generator (6), the infrared detection element (1) passes through the thermal interface (13). When the cold finger (7) absorbs heat, the temperature drops, and when the temperature drops to around 80K, infrared rays transmitted through the window (9) are detected and converted into electric signals. The deuwa (2) prevents heat from entering from the outside by vacuum-insulating the infrared detection element (1) cooled to a cryogenic temperature, and reduces the load on the refrigerator (3). The cold shield (12) attached to the inner shell bottom plate (11) blocks infrared rays other than those that pass through the window (9), for example, infrared rays radiated from the inner surface of the outer shell (8) to detect infrared rays ( The noise of the infrared detection element (1) is reduced by preventing it from entering the 1). Cold shield
Since (12) is attached to the inner shell bottom plate (11), it is cooled to an extremely low temperature together with the infrared sensing element (1), so infrared rays that cause noise in the infrared sensing element (1) are cold shielded. It is not emitted from (12).

[Problems to be solved by the device]

The conventional device as described above has the following problems.

That is, when the infrared detecting element (1) is cooled to a cryogenic temperature by the refrigerator (3), the refrigerator (3) is affected by electrical heat generation of the infrared detecting element (1) itself and radiation or heat conduction from the outside. It must absorb the incoming heat. Refrigerator like this
The larger the heat load on (3), the larger the refrigerator needed and the more power it consumes.
However, the cold shield (1
Since 2) is attached to the bottom plate of the inner shell, the cold shield (12) will also be cooled to an extremely low temperature.
The amount of heat entering the cold shield (12) from the inside of (8) by radiation is large. Therefore, in the conventional device,
Since the heat load on the refrigerator is large, a larger refrigerator is needed, and the power consumption of the refrigerator also increases.

The present invention has been made to solve this problem, and its purpose is to reduce the amount of heat that enters from the inner surface of the outer shell into the cold shield by radiation to reduce the power consumption of the refrigerator. .

[Means for Solving the Problems]

The infrared detector according to this invention has a cold shield attached near the center of the inner shell cylinder.

[Action]

In the infrared detector of this invention, when the refrigerator cools the infrared detecting element to the cryogenic temperature through the inner shell bottom plate, the inner shell cylinder has a polar region from the joint with the inner shell bottom plate to the joint with the outer shell. Since there is a temperature gradient from low temperature to normal temperature, the cold shield is attached near the center where the temperature of the inner shell cylinder is between the extremely low temperature and normal temperature, so the cold shield temperature is lowered as in the conventional device. Absent. Therefore, the amount of heat entering the cold shield from the inner surface of the outer shell by radiation is smaller than that of the conventional device, and the heat load on the refrigerator is smaller than that of the conventional device, so that it is possible to cool with a smaller refrigerator. The power consumption of the refrigerator can be small.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, the infrared detector in (1) and the refrigerator in (3) are the same as the conventional device. The dewa of (2) is different from the conventional device in that the cold shield (12) is attached near the center of the inner shell cylinder (10), and the other parts have the same structure.

In the infrared detector configured as described above, the refrigerator
(3) started operation, and the cold finger of the low temperature generation part (6)
(7) When freezing begins to occur at the tip, infrared detection element (1)
Loses heat to the cold finger (7) through the thermal interface (13) and drops in temperature. When the temperature drops to around 80K, infrared rays transmitted through the window (9) are detected and an electrical signal is detected. It is similar to the conventional device in that it is converted to
When the refrigerator (3) cools the infrared detection element (1) to a cryogenic temperature through the inner shell plate (11), the inner shell bottom plate (11) is attached to the inner shell cylinder (10).
There is a temperature gradient from the cryogenic temperature to room temperature from the joint with the shell to the joint with the outer shell (8).
Since the temperature of the inner shell cylinder (10) is attached near the center where the temperature of the inner shell cylinder (10) is between the extremely low temperature and room temperature, the temperature of the cold shield (12) does not drop as much as the conventional device. Here, the cold shield (12) blocks infrared rays other than those that pass through the window (9), for example, infrared rays emitted from the inner surface of the outer shell (8) so as not to enter the infrared detection element (1). It is that role. Also, the cold shield (12) itself must not radiate infrared rays that cause noise in the infrared detection element (1), so it must be cooled so that the infrared radiation amount becomes small. It is not necessary to cool to extremely low temperature as in 1), for example 200K
If the temperature is cooled down to approximately (-73 ° C), the infrared radiation will be sufficiently small, so the cold shield (12) should be replaced by the inner cylinder (1
The function of (0) can be sufficiently exerted by mounting it near the center where the temperature is between the extremely low temperature and room temperature and cooling it to around 200K.

However, since the temperature of the cold shield (12) is not as low as that of the conventional device, the amount of heat entering from the inner surface of the outer shell (8) into the cold shield (12) by radiation is smaller than that of the conventional device, Since the heat load on the refrigerator (3) is smaller than that of the conventional device, it can be cooled by a smaller refrigerator, and the power consumption of the refrigerator can be reduced.

[Effect of device]

As described above, the present invention has a simple structure in which the cold shield is attached near the center of the inner shell cylinder, so that the amount of heat entering from the inner surface of the outer shell into the cold shield by radiation is smaller than that of the conventional device. Since the heat load applied to the refrigerator is smaller than that of the conventional device, cooling can be performed with a smaller refrigerator, and the power consumption of the refrigerator can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional infrared detector. In the figure, (1) is an infrared detector, (2) is a dewar, (3)
Is a refrigerator, (6) is a low temperature generation part, (8) is an outer shell, (9) is a window, (1
(0) is the inner shell cylinder, (11) is the inner shell bottom plate, and (12) is the cold shield. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] 1. An infrared detecting element which is used after being cooled to an extremely low temperature, an outer shell, an infrared ray-transmitting window attached to the outer shell, and an outer shell having one end attached to the outer shell. A dewar having an inner shell structure having a vacuum shell structure, the inner shell cylinder being covered with the inner shell cylinder, and an inner shell bottom plate that is provided at another end of the inner shell cylinder and holds the infrared detection element; A cold shield that covers the side of the infrared detection element to prevent infrared rays other than those that pass through the window from entering the infrared detection element, and a low temperature generated inside the inner shell tube Infrared detector comprising a refrigerator having a section, wherein the cold shield is attached near the center of the inner shell where the temperature is between an extremely low temperature and a room temperature. vessel.