JPH0618257Y2 - Infrared detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention uses, for example, an infrared detector mounted on an infrared imaging device and used by cooling to an extremely low temperature such as HgCdTe or InSb, for example, around 80K. Infrared detector element.

[Conventional technology]

FIG. 2 is a view showing a conventional infrared detecting device. The infrared detecting device is generally divided into an infrared detecting element (1) and a dewar (2) for vacuum heat insulating the infrared detecting element (1).
And a refrigerator (3) for cooling the infrared detection element (1) to a cryogenic temperature, for example, around 80K. The refrigerator
As (3), refrigerators that use the Stirling cycle or Gifode McMahon cycle are often used, and Fig. 2 shows a refrigerator that uses the Stirling cycle as an example. The refrigerator (3) is composed of the compressor of (4), the low temperature generation part of (5) and the connecting pipe of (6), and the low temperature generation part (5)
Has a long and thin cylindrical projection called cold finger (7), and has a structure in which freezing is generated at the tip of the cold finger (7). The infrared detecting element (1) is attached to the tip of the cold finger (7) and cooled to an extremely low temperature of, for example, about 80K.

The dewar (2) is for insulating the infrared detecting element (1) and the cold finger (7), and has an outer shell of (8),
It is composed of a window (9) attached to the outer shell (8) for transmitting infrared rays, and one end of the outer shell (8) is attached to the flange (10) of the low temperature generating part (5) of the refrigerator (3). The inside of the outer shell (8) is evacuated so as to prevent heat from entering the infrared detecting element (1) and the cold finger (7) from the outside. In addition, at the tip of the cold finger (7), in order to prevent infrared rays other than those passing through the window (9) from entering the infrared detecting element (1), the infrared detecting element (1) A cold shield (12) covering the sides is installed.

Next, the operation of the conventional device shown in FIG. 2 will be described. When the refrigerator (3) starts to operate and freezing occurs at the tip of the cold finger (7) of the low temperature generation part (5), the infrared detection element (1) heats the cold finger (7). Deprived of temperature drop,
When the temperature drops to around 80K, infrared rays transmitted through the window (9) are detected and converted into electric signals. Dewar (2) is an infrared detector (1) and a cold finger that are cooled to a very low temperature.
Vacuum heat insulation of (7) prevents heat from entering from the outside and reduces the load on the refrigerator (3). The cold shield (12) attached to the tip of the cold finger (7) detects infrared rays by blocking 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). Infrared detector element (1) so that it does not enter the element (1)
The noise of is reduced. Since the cold shield (12) is also attached to the tip of the cold finger (7), the cold shield (12) is cooled with the infrared detection element (1) and becomes extremely low temperature, which causes noise of the infrared detection element (1). Infrared rays are not emitted from the cold shield (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 is cooled to a cryogenic temperature by the refrigerator, the refrigerator must absorb the electric heat generated by the infrared detecting element itself and the heat entering from the outside by radiation or heat conduction. The larger the heat load applied to such a refrigerator, the larger the refrigerator required, and the greater the power consumption of the refrigerator. However, since the cold shield is attached to the tip of the cold finger in the conventional infrared detector, the cold shield is also cooled to an extremely low temperature, so that the cold shield enters from the inner surface of the outer shell by radiation. The amount of heat is large. Therefore, the conventional device has a problem that the heat load applied to the refrigerator is large, so that a larger refrigerator is required and the power consumption of the refrigerator also increases.

The present invention has been made to solve such a problem, and an object thereof is to obtain an infrared detector capable of reducing the power consumption of a refrigerator as compared with a conventional device.

[Means for Solving the Problems]

The infrared detector according to the present invention has a cold shield attached near the center between the tip and the root of the cold finger.

[Action]

In the infrared detector of the present invention, when the refrigerator cools the infrared detector element to an extremely low temperature, the cold finger has a temperature gradient from the extremely low temperature to the normal temperature from the tip to the root, and the cold shield has the cold finger. The temperature of the cold shield does not drop as much as the conventional device because it is installed near the center where its temperature is between the extremely low temperature and room temperature. Therefore, the amount of heat that radiates from the inner surface of the outer shell to the cold shield 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. Therefore, it is possible to cool with a smaller refrigerator and consume the refrigerator. It requires less power.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, (1) is the infrared detector and (2) the dewar is the same as the conventional device. The refrigerator of (3) differs from the conventional device in that a cold shield (12) is attached near the center between the tip of the cold finger (7) and the root, and the other configurations are exactly the same.

In the infrared detection device configured as described above, when the refrigerator (3) starts to operate and starts to generate refrigeration at the tip of the cold finger (7) of the low temperature generation part (5), the infrared detection element
In (1), the heat is taken by the cold finger (7) and the temperature drops to 80%.
When the temperature drops to around K, infrared rays that pass through the window (9) are detected and converted into electrical signals, similar to the conventional device, but the refrigerator (3) uses the infrared detection element (1) as a pole. When cooled to a low temperature, the cold finger (7) has a temperature gradient from the tip to the root of the cold finger to the normal temperature, and the cold shield (12) has a temperature of the cold finger (7) at the low temperature and the normal temperature. The temperature of the cold shield (12) does not drop as much as the conventional device because it is installed near the center, which has an intermediate temperature. 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), and the infrared detecting element (1).
Its role is to prevent it from being incident on the cold shield (12) itself, and since the cold shield (12) itself must not radiate infrared rays that cause noise in the infrared detection element (1), the amount of infrared radiation is reduced. Although it must be cooled, it is not necessary to cool it to an extremely low temperature like the infrared detection element (1). For example, if it is cooled to about 200K (about -73 ° C), the amount of infrared radiation will be sufficiently small. Cold shield (1
By attaching 2) near the center of the cold finger (7), which has an intermediate temperature between extremely low temperature and normal temperature, and cooling it to around 200K, the function can be sufficiently achieved. However, since the temperature of the cold shield (12) does not drop as much as that of the conventional device, the amount of heat that penetrates into the cold shield (12) from the inner surface of the outer shell (8) by radiation is smaller than that of the conventional device, and it is more frozen than the conventional device. Since the heat load on the machine (3) is small, it can be cooled by a smaller refrigerator, and the power consumption of the refrigerator can be small.

[Effect of device]

As described above, this device has a simple structure in which the cold shield is attached near the center between the tip and the root of the cold finger, and the amount of heat radiated 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 on the refrigerator is smaller than that of the conventional device, cooling can be performed by 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 detecting device. In the figure, (1) is an infrared detector, (3) is a refrigerator, (7) is a cold finger,
(8) is an outer shell, (9) is a window, and (12) is a cold shield. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A refrigerator having a tubular cold finger for generating an extremely low temperature at its tip, an infrared detection element attached to the tip of said cold finger for use at an extremely low temperature and used, said cold finger and said infrared ray. An outer shell that covers the periphery of the detection element and vacuum-insulates the cold finger and the infrared detection element, a window attached to the outer shell for transmitting infrared rays, and an infrared ray other than the window that transmits the infrared rays is detected as the infrared ray. In an infrared detection device with a cold shield that covers the side of the infrared detection element so as not to enter the element, the cold shield,
An infrared detector characterized in that the cold finger is mounted near the center between the tip and the root of the cold finger, which has an intermediate temperature between extremely low temperature and room temperature.