RU2204812C1 - Infrared radiation detector - Google Patents

Abstract

FIELD: photosensitive equipment designed to detect thermal radiation, cooled semiconductor infrared radiation detectors, in particular. SUBSTANCE: infrared radiation detector includes cryostat in the form of vacuumed Dewar flask anchored in frame and provided with outer and inner inlet windows and gas cryogenic machine which refrigerating finger is located in hole of flange linked to frame and is mounted inside cryostat in space filled with dehumidified gas. Crystal with photosensitive elements is located in gas-filled space and is mounted in close proximity to cold finger. In specific cases of implementation of detector space around cold finger can be additionally filled with heat-insulation material and crystal with photosensitive elements can be anchored on inner inlet window of Dewar flask or on heat-insulation material. Diaphragm put on inner inlet window can be positioned between outer and inner inlet windows of vacuumed Dewar flask. EFFECT: improved photoelectric parameters of detector thanks to reduced vibration and suppression of electromagnetic induction. 5 cl, 2 dwg

Description

 The present invention relates to photosensitive devices designed to detect thermal radiation, in particular to cooled semiconductor infrared (IR) radiation detectors.

 A known infrared radiation receiver containing a vacuum cryostat (Dewar vessel) and a gas cryogenic machine (GCM), the inner cylinder of the cryostat is used as a crystal holder with photosensitive elements (PSE) and at the same time serves as a cold finger GKM (the so-called integrated docking of the cryostat and GKM) (see З. EP 0339836 A2, IPC 4 F 25 B 9/00, 1989). This ensures good thermal insulation between the cooled inner cylinder and the outer wall of the cryostat due to the presence of a vacuum cavity between them, however, since the cryostat is made of metal, the vacuum deteriorates over time due to degassing and leakage, which leads to failure of the entire device. In addition, this design is subject to the influence of vibration and electromagnetic interference, which are transmitted through the cold finger during the operation of the gas compressor and can significantly degrade the output parameters of the receiver.

 A known infrared radiation receiver containing a vacuum-mounted Dewar vessel fixed in a frame is provided with entrance windows, opposite which there is a crystal with photosensitive elements and a diaphragm on the cooled holder, and the sealed cavity formed by the holder, Dewar vessel and the frame is filled with dried gas (see certificate on utility model of the Russian Federation 14666, MKI 7 G 01 J 5/02). This design provides higher reliability of the device, but does not eliminate vibration and electromagnetic interference. In addition, when cooling the GKM device, part of the power is unproductively spent on cooling the holder.

 The technical result of the invention is to improve the photoelectric parameters of the receiver by reducing vibration and eliminating electromagnetic interference.

 The specified technical result is achieved by the fact that in the infrared radiation receiver containing a cryostat, made in the form of a vacuum mounted Dewar vessel fixed in a frame and provided with external and internal input windows, and a gas cryogenic machine, the cold finger of which is placed in the hole of the flange attached to the frame, and mounted inside a cryostat in a cavity filled with dried gas, the crystal with photosensitive elements located in a gas-filled cavity and installed in the immediate vicinity of the cold th finger. In particular cases of execution, the cavity around the cold finger can be additionally filled with heat-insulating material, and a crystal with photosensitive elements is mounted on the internal input window of the Dewar vessel or on heat-insulating material. Between the outer and inner entrance windows of a dewar vessel, a diaphragm may be located mounted on the inner entrance window.

 A crystal with an PSE is located in a gas-filled cavity, installed in the immediate vicinity of a cold finger, and is neither mechanically nor electrically connected to it either when it is fixed on the internal entrance window of a Dewar vessel or when it is mounted on a heat-insulating material, which due to the presence of a massive flange, it almost completely eliminates the vibration and electromagnetic effects during the operation of the gas condensate field.

 Filling the cavity around the holder with insulating material, such as porous glass ceramics, suppresses convective heat transfer, which helps to reduce heat gain to the cooled structural elements and reduce the time it takes to enter the cryostat mode.

 The location of the diaphragm between the entrance windows of the Dewar vessel in the evacuated volume makes it possible to place the internal entrance window in the immediate vicinity of the crystal with PSE, which allows to reduce the gas-filled volume and the length of the inner wall of the Dewar vessel, cooled to the cryostat temperature. This reduces the cooled mass, the load on the cooling system and, ultimately, the time to reach the specified cooling mode.

 The essence of the invention is illustrated by drawings, in FIG. 1 is a diagram of the claimed device, in which a crystal with PSE is mounted on the inner input window of a Dewar vessel, and FIG. 2 is mounted on a thermal insulation material.

 The IR radiation receiver consists of a Dewar vessel 2 fixed in a frame 1 and provided with an external and an internal input window 3 and 4, respectively. A flange 5 is attached to the frame 1, in the opening of which there is a cold finger 6 of the gas cryogenic machine 7, the cavity around which inside the cryostat is filled with dried gas. In special cases, the cavity can be additionally filled with heat-insulating material 8. A crystal with PSE 9 is located in a gas-filled cavity, is installed in the immediate vicinity of a cold finger and is mounted on the inner entrance window 4 of the Dewar vessel (see Fig. 1) or on a heat-insulating material ( see Fig. 2). In addition, between the outer and inner entrance windows of a dewar vessel, a diaphragm 10 may be located mounted on the inner entrance window 4.

 During operation of the device, the crystal is cooled to cryogenic temperatures by a gas cryogenic machine. In this case, due to the movement of the displacing piston in the thin-walled cold finger and the operation of the compressor electric drive in known devices, vibrations and electromagnetic pickups are transmitted through the finger to the crystal through the finger, which degrade the photoelectric parameters of the device. In the proposed design, the crystal with the PSE is not connected either mechanically or electrically with a cold finger due to the presence of a massive flange, which eliminates the unwanted effect from the operation of the gas condensate field and thereby improves the output characteristics of the receiver.

 When used in the construction of a heat-insulating material, there will be a decrease in heat inflow to the cooled elements, since in this case it will be determined not by convective heat transfer, but by the thermal conductivity of the drained gas - heat-insulating material system, which is determined mainly by the thermal conductivity of the dried gas. Therefore, a gain will be obtained in the time required to reach the required temperature regime.

The proposed design was developed for infrared detectors with PSE matrices made of platinum silicide. A glass Dewar vessel with sapphire windows is hermetically welded to a metal frame, which is also hermetically attached to the flange. GKM cold finger ⌀ 6 mm and a wall thickness of ~ 0.1 mm is installed in the hole of the flange with a thickness of ~ 2 mm, and this connection can be made through an elastic element, such as a bellows. A crystal with a PSE matrix is glued to the inner window of a Dewar vessel. The Dewar vessel is evacuated to 10 ^-6 mm RT. Art., and the distance between the crystal and the cold finger is ~ 1 mm, which is mainly due to technological capabilities. The tight cavity around the cold finger is filled with dried nitrogen and porous (~ 95%) glass ceramics, for example, TZMK brand. Placement of the crystal on the heat-insulating material can be carried out either directly by gluing to it, or through washers or other fasteners convenient for assembly or adjustment of the device.

Claims (5)

 1. The IR radiation receiver containing a cryostat, made in the form of a vacuum mounted Dewar vessel fixed in a frame and equipped with external and internal entrance windows, and a gas cryogenic machine, the cold finger of which is placed in the hole of the flange attached to the frame, and is installed inside the cryostat in the cavity, filled with dried gas, and a crystal with photosensitive elements is located in a gas-filled cavity and is installed in the immediate vicinity of a cold finger.  2. The infrared radiation receiver according to claim 1, wherein the crystal with photosensitive elements is mounted on the inner input window of the Dewar vessel.  3. The IR radiation receiver according to claim 1 or 2, in which the cavity is additionally filled with insulating material.  4. The IR radiation receiver according to claim 1, wherein the cavity is additionally filled with heat-insulating material, on which a crystal with photosensitive elements is fixed.  5. The IR radiation receiver according to claim 1, or 2, or 3, or 4, in which a diaphragm is mounted between the external and internal input windows of the dewar vessel of the Dewar installed on the internal input window.

Images