JPH0282122A - Infrared image pickup device - Google Patents

Abstract

PURPOSE:To improve temperature stability by entering light from a cold head which is reflected by a mirror and light from a cold aperture into an image pickup element in addition to infrared light from an object to be picked up which is transmitted through a condenser lens. CONSTITUTION:A vacuum is produced in an image pickup element container 6 and liquefied nitrogen is injected into a container inner cylinder 15 to cool the image pickup element 1 connected to the cold head 2 and the cold aperture to about -200 deg.C. Then, when the image pickup element 1 faces the mirror surface 10 of the inner wall of a lens barrel without fail unless the element faces a 2nd lens 3-2, and the emissivity of the mirror surface 10 and a container internal wall mirror surface 11 is about zero (namely, the reflection factor is about one), so only light 12 from the head 2 and aperture 5 is reflected and made incident on the element 1. Here, the head 2 and aperture 5 are cooled to constant temperature, so even if outside air temperature varies, an image pickup signal does not vary. Therefore, the influence of ambient temperature is removed without decreasing the size of the aperture 5 nor increasing the diameter of the lens.

Description

[Detailed Description of the Invention] [Required] Regarding an infrared + FJI imager equipped with a cold aperture that is a cooled aperture to limit the field of view of an image sensor, output imaging at ambient temperature can be achieved without reducing the cold aperture. In order to eliminate the influence on the signal, it consists of an image sensor that is cooled by a cold head, photoelectrically converts infrared light from the object to be imaged and outputs an image signal, and a lens closest to the image sensor. A total of two or more light condensing lenses mounted at the position of the window on the front surface of the image pickup device container or sufficiently close to the window, and between the two or more light condensing lenses and the image pickup device. provided, the RI
& a cold aperture to limit the field of view of the element,
an inner wall of an illumination tube that fixedly supports the one lens or an inner wall of a portion of the window that does not transmit infrared light to the image sensor, and a mirror surface formed on an inner wall of the image sensor container, respectively; The imaging device is configured to view only the infrared light transmitted through the lens and the cold aperture or cold head reflected by the mirror surface.

[Industrial application field]

The present invention relates to an infrared imaging device, and more particularly to an infrared imaging device equipped with a cold aperture, which is a cooled aperture to limit the field of view of an m@ element.

As shown in FIG. 4, the infrared imaging device includes an infrared R8I element 1 mounted on a cold head 2, and an aFII
Infrared rays are incident on the element 1 through a lens 3 for condensing light, a window 4 made of, for example, germanium (Ge) that transmits infrared rays, and a cold aperture 5.

Image sensor 1, cold head 2, cold aperture 5
is housed in an imaging device container 6 made of glass, for example, and a part of the imaging device container 6 is provided with the window 4 . The interior of the image sensor container 6 is kept in a vacuum. The lens 3 is attached to a lens barrel 7.

The cold aperture 5 is provided between the image sensor 1 and the lens 3, and mainly limits infrared light from the lens 3 (in other words, by limiting the field of view 8 of the image sensor 1, it prevents infrared light from entering the image sensor 1. limit background light from the imaged subject)
This purpose also serves to prevent the image sensor 1 from looking into objects other than the lens surface, such as the lens barrel 7.

In this way, in an infrared imaging device equipped with the cold aperture 5, which is a cooled opening, it is important that the cold aperture 5 has a structure that can sufficiently achieve the above purpose.

[Conventional technology]

When the image sensor 1 looks into a part of the device other than the lens surface, if the temperature of the device changes due to a change in the ambient temperature,
Since the infrared light incident on the image sensor 1 also changes, the output imaging signal of the image sensor 1 changes even though the object to be imaged does not change, causing a problem. For this reason, by matching the size and positional relationship between the cold aperture 5 and the lens 3, the image sensor 1 is configured to view only the lens surface.

For example, in the case of a one-dimensional linear array type carrier (II cable 1a) as shown in FIG. So,
The cold aperture 5a has a rectangular opening according to the shape of the image sensor 1a.

Figure 6 shows the conventional infrared rays using this linear array type image sensor! A configuration diagram of an example of IiS image installation is shown, and the same figure (A)
4 is a configuration diagram of the image sensor 1a viewed from the Y direction, and FIG. 4B is a configuration diagram viewed from the X direction. Omitted.

As shown in FIG. 6 (A>), the cold aperture 5a allows the imaging device 1a to see only the lens surface of the lens 3.

FIG. 7 shows a configuration diagram of another example of a conventional infrared imaging device. In the same figure, the same components as in FIG. 4 are given the same reference numerals.
The explanation will be omitted. This conventional example uses two condensing lenses.
The first and second lenses 3-1 and 3-2 are arranged in front of the infrared light incident surface of the window 4. The first and second lenses 3-1 and 3-2 are held by first and second lens barrels 7-1 and 7-2.

According to this conventional example, two condensing lenses 31 and 3 are used.
-2, the lens diameter can be made considerably smaller than that of the conventional example shown in FIG.

[Problem to be solved by the invention]

However, in the conventional device shown in FIG. 6, in the X direction of the linear array type image sensor 1a, the image sensor 1a can be configured to look into only the lens surface as shown in FIG. As for the direction, as shown in FIG. 2B, since the cold aperture 5a is wide in order to secure the field of view of the light receiving element 1a-1 at the end, the imaging element 1a looks into the inner wall of the lens barrel 7 other than the lens.

This point can be solved by reducing the opening area of the cold aperture 5a and increasing the lens diameter of the lens 3 to a certain extent, but reducing the opening area of the cold aperture 5a will lead to a decrease in sensitivity. , and if the diameter of the lens 3 is increased, the cost will increase.
The shape will also become larger.

In particular, when the number of light-receiving elements of the image sensor 1a increases and the size becomes larger, the ms element 1 as shown in FIG.
It is very difficult to realize the positional relationship between the a1 cold aperture 5a and the lens 3.

Also, in the conventional device shown in FIG. 7, in the y direction of the linear array type image sensor 1a, as shown in FIG. The inner wall of the lens barrel 7-2 of No. 2 is 11i.
Since the image element 1a is visible, either the frontage area of the cold aperture 5a should be made smaller or the lens 3-1.3-2
It was necessary to increase the diameter of the sensor, which resulted in a decrease in sensitivity, an increase in cost, and an increase in size.

The present invention has been made in view of the above points, and an object of the present invention is to provide an infrared imaging device that can eliminate the influence of ambient temperature on an output imaging signal without reducing the cold aperture.

(Means for Solving the Problem) FIG. 1 shows a diagram of the principle of the present invention. In the figure, the same components as those in FIG. 4 are designated by the same reference numerals, and their explanations will be omitted.

The number of condensing lenses is n (n is an integer of 2 or more), and each of the lenses 3-1 to 3-n is connected to a lens barrel 7-1 to 7-n.
The lens 3-n, which is the closest to the V&image element 1, is attached to the front surface of the tension element container 6 at the position where the window should be.

A mirror surface 10 is formed on the inner wall of the lens barrel 7-n, and a mirror surface 11 is formed on the inner wall of the imaging device container 6, respectively.

In addition, the above-mentioned lens 3-n may be provided not at the window position but at a position close to the window. In that case, the mirror surface is such that the infrared light is directed to the inner wall of the image sensor container 6 and the image sensor 1 of the window. They are formed on the inner walls of the portions that do not pass through.

As a result, in addition to the infrared light transmitted through the lenses 3-1 to 3-n, the image sensor 1 reflects the infrared light on the mirror surfaces 10.11, etc.
Cooled cold aperture 5 or cold head 2
You will only see

(Function) When the image sensor 1 looks at a lens other than the lens 3-n, the incident light 12
As shown, the light from the cold head 2 and the cold aperture 5 will be seen.

However, cold head 2 and cold aperture 5
Each surface is treated with a black body, so no reflection occurs.

Further, the cold head 2 and the cold aperture 5 are each cooled and maintained at a constant temperature regardless of changes in ambient temperature.

Therefore, the infrared light incident on the image sensor 1 comes from the II image object, and from the cold head 2 and the cold aperture 5, but the temperatures of the two are quite different, and the temperature of the latter (cooling temperature) is The temperature changes and the lens barrel 7-n
Since the temperature of the 1Fll image element 6 remains constant even if the temperature changes, it can be distinguished from the infrared light of the object to be imaged.

〔Example〕

FIG. 2 shows a configuration diagram of a first embodiment of the present invention.

In the figure, the same components as in FIG. 1 are denoted by the same reference numerals, and their explanations will be omitted. This example has two lenses (n=
2>, the first lens 3-1 is a focus adjuster M413.
The second lens 3-2 is fixed to the imaging device container 6 by a lens barrel 7-2. Reference numeral 14 denotes a housing of the camera head section, which is screwed together with t[7-1 of the first lens.

The interior of the imaging device container 6 is a vacuum, and the imaging device 1 connected to the cold head 2 and the cold aperture 5 can be connected to each other by injecting liquid nitrogen into the container inner cylinder 15 or inserting a J-T cooler. is cooled to, for example, about -200°C. Further, a signal wiring 16 for driving and signal output is drawn out from the image sensor 1 to the outside of the container 6.

Inner wall of #A cylinder 7-2 of second lens and imaging cord container 6
For example, aluminum (Ag) is deposited on the inner walls of the mirror surfaces 10 and 11 to form mirror surfaces 10 and 11, respectively. Also,
The surfaces of the cold head 2 and the cold aperture 5 are each subjected to blackbody treatment.

With the above configuration, the imaging probe 1 is connected to the second lens 3.
If you look at anything other than -2, you will always look at the mirror surface 10 on the inner wall of the lens barrel, and the mirror surface 10 on the inner wall of the lens barrel and the mirror surface 11 on the inner wall of the container have an emissivity of 0 (that is, a reflectance of 1), so it is cold. Light 12 from the head 2 and the cold aperture 5 is reflected and incident on the image sensor 1.

Since the cold head 2 and the cold aperture 5 are each cooled to a constant temperature, even if the outside air temperature changes and the temperature of the apparatus changes, the imaging signal will not change unless the temperature of the object to be imaged changes. Therefore, according to this embodiment, even if the size of the cold aperture 5 is not made small or the lens diameter is not made large, when the image sensor 1 has a shape such as the above-mentioned or near array type image sensor 1a, However, the influence of ambient humidity can be eliminated.

Furthermore, in this embodiment, the positional relationship between the image sensor 1, the cold aperture 5, and the lens barrel 7-2 of the second lens does not have to be strict, and the size of the image sensor 1, the cold aperture 5, and the
Even if the size of the second lens 3-2 and the II cylinder 7-2 are changed, there is no need to replace the second lens 3-2 and the II cylinder 7-2, which can reduce costs.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 shows the main parts of a second embodiment of the present invention, and the same components as those in FIG.

In this embodiment, there is a window 4, and a second
This embodiment is similar to the conventional device shown in FIG. 7 in that the lens 3-2 is brought sufficiently close to the lens 3-2, but unlike this conventional device, this example Mirror surfaces 11 and 17 are formed in each portion by Ae vapor deposition.

Here, the window 4 is an infrared light transmitting portion 4a that exists in the optical path of infrared light from the second lens 3-2 to the image sensor 1.
and an infrared light J[transmissive part, of which the above-mentioned mirror surface 17 is formed only in the infrared light non-transmissive part.

In this embodiment, compared to the first embodiment, each radius of the lens 3-1.32 may be increased by (j+, dz.d+,
Since dz is not a very large value, the lens diameter of this embodiment is only slightly larger than that of the first embodiment, and the same effect as that of the first embodiment can be achieved without reducing the opening area of the cold aperture 5. is obtained.

〔Effect of the invention〕

As described above, according to the present invention, in addition to the infrared light from the object to be imaged that passes through the condensing lens, the incident light of the LFI image element includes light from the cold head and cold aperture reflected by the mirror surface. Since the II image element is a linear array type [one element, even if it is difficult to match the size and positional relationship of the cold aperture and the condensing lens due to its shape, It is possible to obtain imaging signals using infrared light from the object to be imaged without being affected by the ambient temperature without reducing the aperture area of the cold aperture or increasing the lens diameter. , thus improving temperature stability without reducing sensitivity, increasing cost, or increasing size.
It has features such as being able to improve performance.

[Brief explanation of the drawing]

Figure 1 is a principle diagram of the present invention, Figures 2 and 243 are the components of each embodiment of the present invention, Figure 4 is a schematic configuration diagram of an infrared imaging device, and Figure 5 is a linear array type carrier @ element. Figures 6 and 7, which show the positional relationship with the cold aperture, are respective configuration diagrams of the conventional apparatus. In the figure, 1 is a Sho image element, 2 is a cold head, 3-1 to 3-n are lenses, 4 is a window, 5 is a cold aperture, 6 is a pupil image container, and 7-1 to 7-n are mirrors. 10 is a mirror surface of the inner wall of the lens barrel; 11 is a mirror surface of the inner wall of the container; 12 is incident light from a source other than the lens; 17 is a mirror surface of the window. Field of view 8 Output signal Fig. 2 A diagram of the principle of the invention Fig. 1 A diagram of the arrangement of the second embodiment of the invention Fig. 3 Output signal - Diagram showing the positional relationship with Cha

Claims (1)

[Claims] An imaging device (1) that is cooled by a cold head (2), photoelectrically converts infrared light from an imaging target, and outputs an imaging signal.
), and one lens (3-n) closest to the image sensor (1) is installed at the position of the window (4) on the front surface of the image sensor container (6) or sufficiently close to the window (4). 2 in total
at least one light condensing lens (3-1 to 3-n); and between the two or more light condensing lenses (3-1 to 3-n) and the image sensor (1). a cold aperture (5) for limiting the field of view of the image sensor (1); and a lens barrel (7-n) for fixedly supporting the one lens (3-n).
n) or the image sensor (1) of the window (4).
mirror surfaces (10, 1) formed on the inner wall of the infrared light non-transmissive portion (4a) to
1, 17), and the image sensor (1) is equipped with a lens (3
-1 to 3-n) and the infrared light passing through the mirror surface (
10, 11, 17). An infrared imaging device characterized in that only the cold aperture (5) or the cold head (2) reflected by the object (10, 11, 17) is viewed.