JPH02245621A - Correction of output voltage of infrared detector - Google Patents

Abstract

PURPOSE:To obtain a better infrared image by correcting infrared rays from outside a lens varying with an environmental temperature for each of infrared detecting elements of a two-dimensional infrared detector. CONSTITUTION:A black body plate 36 is set in the perimeter of a lens 34. A cold shield 30 having an opening 30a made by a black body treatment of copal is provided on the top of an inner cylinder 16 of a cooling container. An angle of field of view of infrared rays from outside the lens 34 to be incident into infrared detecting elements is determined by a positional relationship of the lens 34, shield 30 and an infrared detecting element 24. Therefore, when the black body plate 36 is set in the perimeter of the lens 34, an angle of field of view of the black body plate 36 allowed for the elements 24 is also determined. As an environmental temperature varies, a quantity of infrared rays from the black body plate 36 changes. But, the quantity of the infrared rays from the black body plate 36 allowed for the elements 24 can be corrected by learning a quantity of infrared rays per unit angle of field of view allowed for a second infrared detector 38. This enables correction of variations in output of the detector 24 associated with a change in the environmental temperature thereby enabling the obtaining of a better infrared image.

Description

[Detailed Description of the Invention] Summary Regarding a method for correcting the output voltage of an infrared detector, the objective is to effectively correct the influence of infrared rays incident from outside the lens, which changes depending on the environmental temperature, and to obtain a good infrared image. and a method for correcting the output voltage of an infrared detection device, in which the infrared rays from the vicinity of 1/2 infrared rays are restricted by a cold shield, and the infrared rays are made incident on a two-dimensional infrared detector configured by arranging a plurality of infrared detection elements two-dimensionally. A second infrared detector consisting of a single infrared detecting element having the same characteristics as the infrared detecting element constituting the two-dimensional infrared detector is installed on the right side of the lens, and a black body plate is installed around the lens. installed in the same plane as the infrared detector and in a position where the entire field of view seen through the opening of the cold shield is a black body board,
The viewing angle at which each infrared sensing element constituting the two-dimensional infrared detector views the black body plate is determined in advance, and the viewing angle at which each infrared sensing element of the two-dimensional infrared detector views the black body plate, and the second The output voltage of the second infrared detector is multiplied by the ratio of the viewing angle at which the infrared detector looks into the black body, and the value is 2.
It is configured to be subtracted from the output voltage of each infrared sensing element constituting the dimensional infrared detector.

FIELD OF THE INVENTION The present invention relates to a method for correcting the output voltage of an infrared detector (infrared sensor).

Infrared sensors include calorimetric sensors that use pyroelectric elements, thermopiles, etc., and photoelectric effect (quantum) sensors that use semiconductors. Calorie sensors generally have no wavelength dependence in sensitivity, but their low sensitivity and slow response speed make them unsuitable as real-time infrared sensors. On the other hand, photoelectric effect sensors have high sensitivity and fast response speed, but require cooling of the device to liquid nitrogen temperature. Photoelectric effect type infrared sensors are classified into photoconductive type, photovoltaic type, and MIS type. Among these, the photoconductive sensor utilizes a change in resistance upon irradiation with light, and includes cadmium mercury telluride (HgCdTe) and the like.

Such infrared sensors (infrared detectors) are used for weather observation using artificial satellites, crime prevention, disaster prevention, geological and resource surveys, and medical purposes using infrared thermography. Consisting of two-dimensional array of infrared sensing elements (light receiving elements) 2
In a dimensional infrared detector, the amount of background infrared radiation from outside the lens changes as the environmental temperature changes. the result,
There is a problem in that the output voltage of the infrared detector changes and the brightness of the image fluctuates. Therefore, there is a need for an infrared detector that suppresses fluctuations in image brightness.

Conventional technology FIG. 2 is an overall configuration diagram of a typical infrared detection device.

10 is a vacuum cooling container, which is mounted on a helium circulation cooler 12. The vacuum cooling container 10 includes an outer tube 14 made of Kovar and an inner tube 16 made of Kovar glass. Both the outer tube 14 and the inner tube 16 are mounted on a mounting member 18 made of Kovar. A mounting member 18 is secured on a support member 20 attached to the helium circulating cooler 12. Reference numeral 22 denotes an annular ceramic substrate for taking out lead wires from the vacuum cooling container 10 to the outside, and is attached to the outer tube 14 in a sandwich manner.

A two-dimensional infrared detector 2 composed of a plurality of infrared detection elements such as HgCdTe is mounted on the upper end surface (cooling surface) of the inner cylinder 16.
4 is glued. The upper end surface (cooling surface) of the inner cylinder 16 is mounted on the circulation cooler 120 rod 26 via a thermally conductive spring 28, and the tip of the rod 26 made of SUS is heated by adiabatically expanding helium. When unloaded, it is cooled to about 50°C. A gold pattern is formed on the outer circumferential surface of the inner cylinder 16 and the surface of the annular ceramic substrate 22, and the bonding pad portion of the infrared detector 24 and the gold pattern of the inner cylinder 16 are bonded and connected with a bonding wire 25. The gold pattern No. 16 and the gold pattern on the annular ceramic substrate are bonded and connected by a bonding wire 27.

30 is a cold shield having an opening 30a;
It is formed by processing fish body on Kobar. Further, the outer cylinder 14 is provided with a germanium window 14a that transmits infrared rays. A lens 34 is made of germanium and is attached to the housing 32 of the infrared detection device.

By driving the helium circulating cooler 12, the infrared detector 24 mounted on the inner tube 16 made of Kovar glass is cooled to about the temperature of liquid nitrogen, and the infrared rays entering through the lens 34 and the germanium window 14a are cooled. Images can be detected.

In order to cool the infrared detector 824 to an extremely low temperature, in addition to the above-mentioned helium circulation cooler, a method of cooling with liquid nitrogen is also generally employed.

Problems to be Solved by the Invention As mentioned above, in a two-dimensional infrared detector constructed by arranging a plurality of infrared detecting elements in a two-dimensional manner, the amount of background infrared radiation from the field outside the lens changes as the environmental temperature changes. . As a result, there is a problem in that the output voltage of the infrared detector changes and the brightness of the infrared image fluctuates. This is the third
This will be explained with reference to the figures. As shown in FIG. 3, the field of view of the two-dimensional infrared detector 24 is limited by a cold shield 30. This prevents infrared rays that do not pass through the lens 34 from entering the two-dimensional infrared detector 24. However, the center (A) and end (B) of the infrared detector 24
Then, the field of view determined by cold shield 3° is different, and the edge! B (B) Infrared rays from outside the lens are incident. Since the infrared detecting element located at point A in FIG. 3 is provided on the lens axis, infrared rays from outside the lens do not enter.

However, the infrared rays outside the lens shown by the hatched area in FIG. 3 are incident on the infrared sensing element at point B, which constitutes the end of the two-dimensional infrared detector 24. That is, infrared rays outside the lens with a viewing angle α1 are incident.

This poses a problem in that the edges of the infrared image displayed on the monitor appear whitish compared to the center, and the degree of whitishness changes depending on the environmental temperature.

The present invention has been made in view of these points, and its purpose is to effectively correct the influence of infrared rays incident from outside the lens, which changes depending on the environmental temperature, and to realize good infrared images. An object of the present invention is to provide a method for correcting the output voltage of an infrared detector.

Means for Solving the Problems An infrared detection device in which infrared rays from the lens and the periphery of the lens are restricted by a cold shield, and the infrared rays are made to enter a two-dimensional infrared detector configured by arranging a plurality of infrared detection elements two-dimensionally. A black body plate is installed around the lens, and a second infrared detector consisting of a single infrared detecting element having the same characteristics as the infrared detecting element constituting the two-dimensional infrared detector is connected to the two-dimensional infrared detector. and at a position where the field of view seen through the opening of the cold shield is entirely the black body plate.

Then, the viewing angle at which each infrared detecting element constituting the two-dimensional infrared detector looks into the black body plate is determined in advance, and then
The output voltage of the second infrared detector is multiplied by the ratio of the viewing angle at which each infrared sensing element of the dimensional infrared detector views the black body plate and the viewing angle at which the second infrared detector views the black body plate. Finally, the output voltage of the two-dimensional infrared detector is corrected by subtracting the value of this output voltage from the output voltage of each infrared sensing element constituting the two-dimensional infrared detector.

Function The viewing angle of the infrared light outside the lens that enters each infrared sensing element is determined by the positional relationship of the lens, cold shield, and infrared sensing element. Therefore, when a black body plate is installed around the lens as described above, the viewing angle of the black body plate seen by each infrared detection element is also determined. When the environmental temperature changes, the amount of infrared light from the black body plate changes, but by knowing the amount of infrared light per unit viewing angle that the second infrared detector sees, it is possible to adjust the amount of infrared light from the black body board that each infrared sensing element sees. The amount of light can be corrected. As a result, 2
It is possible to correct output fluctuations of the dimensional infrared detector and obtain good infrared images.

EXAMPLES The present invention will be explained in detail below based on examples shown in the drawings. In the description of this embodiment, components that are substantially the same as those of the prior art shown in FIGS. 2 and 3 will be described with the same reference numerals.

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention. In this embodiment, for convenience of explanation, the outer cylinder, circulation cooler, casing of the infrared detection device, etc. shown in FIG. 2 are omitted. lens 3
Black body boards 3 and 6 are installed around 40. The installation of this black body board is actually the 21st! This is achieved by blackbody processing the casing shown in I. A cold shield 30 having an opening 30a obtained by blackbody-treated Kovar is provided at the upper part of the inner cylinder 16 of the cooling container made of Kovar glass. A two-dimensional infrared detector 24 is provided approximately in the center of the cooling surface 16a of the inner cylinder 16, and is configured by arranging a plurality of infrared detecting elements two-dimensionally. moreover,
On this cooling surface 16a, a second infrared detector 38 consisting of a single infrared detecting element having the same characteristics as the infrared detecting element constituting the two-dimensional infrared detector 24 is inserted through the opening 30a of the cold shield 30. It is installed at a position where the entire visible field of view is the black body plate 36. The present invention corrects the output voltage of each infrared detection element constituting the two-dimensional infrared detector 24 based on the output voltage of the second infrared detector 38.

That is, in the present invention, the output voltage of each infrared sensing element is corrected as shown in the following equation.

α2 Here, vl: Output voltage of each infrared sensing element of the two-dimensional infrared detector, ■2=Output voltage of the second infrared detector, α1: Outside the lens of each infrared sensing element constituting the two-dimensional infrared detector Viewing angle, α2: Viewing angle of the second infrared detector.

In this way, by correcting the output voltage of the infrared sensing element constituting the two-dimensional infrared detector based on the output voltage of the second infrared detector, it is possible to suppress the influence of the infrared region beyond the lens. , good infrared images can be obtained.

Effects of the Invention Since the present invention is configured as detailed above, it is possible to correct infrared rays from outside the lens, which vary depending on the environmental temperature, for each infrared sensing element of a two-dimensional infrared detector. This has the effect of realizing images.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, FIG. 2 is an overall configuration diagram of a typical infrared detection device, and FIG. 3 is a diagram illustrating problems with the conventional device. 0... Vacuum cooling container, 2... Helium circulation cooler, 4a... Germanium window, 6... Inner cylinder, 4... Two-dimensional infrared detector, 0... Cold shield, 4. ...Lens, 6...Black body plate, 8...Second infrared detector. 16q: 24: 30: 34: Saizu P Zhao 2) gu〒-Ato outside *N test Hiro 6; : 82 ＞/jttP! 1412: Weihuan Retrospective I
ll dairy 14, Tato deriri 28: Sei Houjin pillar r1゛ki father Fu! Red Shield 34, Resis 1 Mikuto Takane; Utaminu de Yumai 1 Is it a side cane? Figure 3 of the light map

Claims (1)

[Claims] A two-dimensional infrared detector (24) configured by arranging a plurality of infrared detecting elements two-dimensionally, limiting infrared rays from the lens (34) and the periphery of the lens with a cold shield (30).
), in which a black body plate (36) is installed around the lens, and an infrared detecting element having the same characteristics as the infrared detecting element constituting the two-dimensional infrared detector (24) is installed. A second infrared detector (38) composed of one infrared detection element is installed on the same plane as the two-dimensional infrared detector (24) and on the same plane as the cold shield (30).
) is installed at a position where the entire field of view seen through the opening (30a) is the black body plate (36), and each infrared detecting element constituting the two-dimensional infrared detector (24) is placed in the black body plate (36).
6) is determined in advance, and the viewing angle at which each infrared sensing element of the two-dimensional infrared detector (24) looks at the black body plate (36), and the viewing angle at which the second infrared detector (38) looks at the black body plate are determined in advance. Multiply the output voltage of the second infrared detector (38) by the ratio of the viewing angle looking into the plate (36), and subtract that value from the output voltage of each infrared detection element that makes up the two-dimensional infrared detector (24). A method for correcting the output voltage of an infrared detector, characterized in that: