JPH05264341A - Infrared detector with cold shield - Google Patents

Abstract

PURPOSE:To obtain an infrared detector with a cold shield which is so constructed as to prevent breakdown of the cold shield and a glass inner tube. CONSTITUTION:In an infrared detector with a cold shield wherein a sapphire substrate 12' having multi-element type infrared-ray detecting elements 10 on the surface is bonded on a glass inner tube 6 and the cold shield 14 having an opening 14a formed opposite to each element 10 is so provided on the sapphire substrate 12' as to be separated at a prescribed gap therefrom, the sapphire substrate 12' is formed to be longer than the cold shield 14. The cold shield 14 is fixed on the sapphire substrate 12' by a bonding agent 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared detector with a cold shield. Since the infrared detector can know the existence, shape, temperature, composition, etc. of an object without touching the target object, it can be used for weather observation with satellites, crime prevention, disaster prevention, geological / resource surveys, medical use with infrared thermography, etc. It is used in many fields.

Among such infrared detectors, a photoelectric effect type infrared detector utilizing a binary or ternary compound semiconductor is
Although the sensitivity is high and the response speed is fast, it is usually necessary to cool the device at approximately the liquid nitrogen temperature.

In order to increase the detection sensitivity of the infrared detector, it is necessary to narrow the viewing angle of infrared rays incident on the light receiving portion from the object to be detected as much as possible and eliminate extra radiation coming from the background other than the object to be detected. desirable. For this reason, a shielding member that limits the viewing angle is arranged on the infrared ray incident side of the light receiving unit to eliminate the radiation from the background.

In this case, when the temperature of the shielding member is high, the radiation from the shielding member deteriorates the detection sensitivity. Therefore, the shielding member is used by being cooled to a low temperature like the detection element, and the shielding member is a cold shield. Is called.

[0005]

2. Description of the Related Art An outline of a conventional infrared detector will be described with reference to FIG. In FIG. 3, the vacuum heat insulating container 2 is a container having a dual structure which is composed of an outer cylinder 4 and an inner cylinder 6, and a high vacuum is drawn between the inner and outer cylinders.

A bandpass filter 8 is attached to the upper portion of the outer cylinder 4 to define an infrared transmission window and also serve as a filter for limiting the detection wavelength band. The inner cylinder 6 is made of glass, and the sapphire substrate 12 of the infrared detection element 10 is fixed to the upper surface of the inner cylinder 6 with an adhesive.

As best shown in the enlarged view of FIG.
A multi-element type infrared sensing element 10 is bonded to the upper surface of the sapphire substrate 12, and a cold shield 14 with an individual aperture that defines an opening (aperture) 14 a facing each sensing element 10 is formed by an In bump 18 using a sapphire substrate. It is installed on the sapphire substrate at a predetermined distance from 12.

The cold shield 14 determines the viewing angle of each detecting element 10 and also prevents stray light incident from other than the viewing angle. The cold shield 14 is attached to a reinforcing metal aperture 16 having a large opening 16a.

The cold shield 14 placed on the sapphire substrate 12 at a predetermined distance by the In bump 18 is fixed to the top of the inner cylinder 6 by the adhesive 20 together with the metal aperture 16.

[0010]

However, in the conventional example in which the cold shield 14 is fixed to the inner cylinder 6 with the adhesive 20, the cold shield 14, the glass inner cylinder 6 and the adhesive 20 are used.
Thermal expansion coefficient of 6.9 × 10 ^{−6 /} K, 4.5 ×
Since it is 10 ⁻⁶ / K and 3.0 × 10 ⁻⁵ / K, the adhesive agent 20 will be applied when the infrared detection element mounting portion is cooled to approximately liquid nitrogen temperature due to the difference in the thermal expansion coefficient of the three. There is a problem that a crack is generated in the glass cylinder 6 portion to which the above is applied, or a crack is generated in the cold shield 14.

The present invention has been made in view of the above points, and an object of the present invention is to provide an infrared detector with a cold shield which prevents damage to the cold shield and the inner glass tube. Is.

[0012]

In order to solve the above-mentioned problems, the present invention provides a sapphire substrate having a multi-element infrared detecting element on its surface, which is adhered onto a glass inner cylinder, and an opening facing each element. In an infrared detector with a cold shield, which is installed on the sapphire substrate with a cold shield defining a predetermined distance, the sapphire substrate is formed longer by the cold shield, and the cold shield is bonded onto the sapphire substrate with an adhesive. An infrared detector with a cold shield is provided, which is characterized by being fixed by.

Instead of the above-mentioned structure, a fixed block made of a material having a coefficient of thermal expansion close to that of the cold shield is attached on the glass inner cylinders adjacent to both ends of the sapphire substrate, and the cold shield is It may be fixed on the fixing block with an adhesive.

[0014]

[Function] Since the cold shield is fixed on the sapphire substrate whose coefficient of thermal expansion is close to that of the cold shield with an adhesive, the glass inner cylinder and the cold shield are cracked even when the infrared detector mounting part is cooled to approximately liquid nitrogen temperature. Are prevented from entering. This makes it possible to provide a highly reliable infrared detector.

Similar effects can be obtained when the cold shield is fixed on the fixing block with an adhesive.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the description of this embodiment, the same reference numerals will be given to substantially the same components as those of the conventional example shown in FIGS. 3 and 4.

Referring to FIG. 1, there is shown a cross-sectional view of an embodiment of the present invention. Reference numeral 12 'is a sapphire substrate to which the multi-element type infrared detection element 10 formed of a compound semiconductor crystal such as HgCdTe is attached, which is formed longer than the cold shield 14 and is attached to the glass inner cylinder 6 with an adhesive. Has been done.

The cold shield 14 is made of ZnS and has a plurality of openings (apertures) 14a facing the infrared detecting element 10. The cold shield 14 is attached to the metal aperture 16 that defines the opening 16a, and the In bump 18 forms the sapphire substrate 1.
It is mounted on a sapphire substrate 12 'with a predetermined distance from 2'.

The cold shield 14 is fixed on the sapphire substrate 12 'by an adhesive 20. As described above, when the cold shield 14 is directly fixed on the sapphire substrate 12 'with an adhesive, the cold shield formed of ZnS (coefficient of thermal expansion 6.9 × 10 ^-6 / K) and the sapphire substrate 12' (coefficient of thermal expansion) are used. The difference in the coefficient of thermal expansion between 5.3 × 10 ⁻⁶ / K) and the adhesive 20 (coefficient of thermal expansion 3.0 × 10 ⁻⁵ / K) is the cold shield according to the conventional fixing method shown in FIG. Since it is smaller than the difference in the coefficient of thermal expansion among 14, the glass inner cylinder 6, and the adhesive 20, the cold shield 14 hardly cracks when the element mounting portion is cooled to approximately the liquid nitrogen temperature.

Since the adhesive 20 does not directly contact the inner glass tube 6, it is possible to prevent the inner glass tube 6 from cracking as in the conventional case. FIG. 2 shows a cross section of another embodiment of the present invention. According to this embodiment, the fixing blocks 22 made of sapphire are fixed on the inner glass tube 6 adjacent to both ends of the sapphire substrate 12 with an adhesive.

Then, the cold shield 14 'and the metal aperture 16' made of ZnS are formed to be a little long to overhang the sapphire substrate 12, and the In shield 24 supports the cold shield 14 'on the fixed block 22. Then, the cold shield 14 ′ and the metal aperture 16 ′ are fixed to the fixing block 22 with the adhesive 20 with the adhesive 20.

As described above, instead of forming the sapphire substrate as long as in the embodiment of FIG. 1, a pair of fixed blocks 22 are independently provided at both ends of the sapphire substrate 12, and the cold shield 14 is attached to these fixed blocks 22. Even if ′ is fixed, the cold shield 14 ′ is prevented from cracking as in the embodiment shown in FIG.

In the embodiment shown in FIG. 2, the fixed block 22
However, the material of the fixed block 22 is not limited to sapphire, and another material having a thermal expansion coefficient close to that of the cold shield 14 'can be used.

[0024]

Since the present invention is configured as described above in detail, when the element mounting portion is cooled to a low temperature, the cold shield and the inner cylinder are prevented from cracking, and a highly reliable cold shield is provided. It is possible to provide an infrared detector.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a schematic sectional view of a conventional infrared detector.

4 is an enlarged cross-sectional view of the conventional example shown in FIG.

[Explanation of symbols]

 6 Glass Inner Cylinder 10 Infrared Detector 12 Sapphire Substrate 14, 14 'Cold Shield 16, 16' Metal Aperture 20 Adhesive 22 Fixed Block

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomofumi Ueda 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited

Claims (3)

[Claims] 1. A sapphire substrate (12, 12 ') having a multi-element type infrared detecting element (10) on its surface is adhered onto a glass inner cylinder (6), and an opening (14a facing each element (10) is provided. In the infrared detector with a cold shield, the cold shield (14, 14 ') defining the above (4) is installed on the sapphire substrate (12, 12') at a predetermined interval. Shield (1
4), the cold shield (1) is formed on the sapphire substrate (12 ′).
An infrared detector with a cold shield, characterized in that 4) is fixed with an adhesive (20). 2. A sapphire substrate (12, 12 ') having a multi-element infrared detecting element (10) on its surface is adhered onto a glass inner cylinder (6), and an opening (14a facing each element (10a) is formed. In the infrared detector with a cold shield, which is installed on the sapphire substrate (12, 12 ') with a predetermined distance between the cold shields (14, 14') defining the A fixed block (22) made of a material having a thermal expansion coefficient close to that of the cold shield (14 ') on the glass inner cylinder (6)
An infrared detector with a cold shield, characterized in that the cold shield (14 ′) is fixed to the fixing block (22) with an adhesive (20). 3. The infrared detector with a cold shield according to claim 2, wherein the fixed block (22) is made of sapphire.