JPH0735611A - Infrared camera - Google Patents

Abstract

PURPOSE:To achieve an increase in the number of pixels in a photodetecting area with the facilitating of the production, cooling and shielding of an infrared detector by a method wherein an incident end of an infrared waveguide is arranged in linearly and an emission end thereof in an area to perform a photoelectric conversion of an emission light from the area-shaped emission end with an area infrared detector. CONSTITUTION:In an infrared imaging optical system 1, radiation infrared rays from an object are focused to form an image on a linear incident end face 2a of an infrared fiber bundle 2. Incident infrared rays are transmitted through fibers of the infrared fiber bundle 2 with the number thereof corresponding to the number of pixels to be emitted at an area-shaped emission end face 2b. The light emitted forms an image on an infrared detector 4 through an infrared relay optical system 3. The detector 4 is an area sensor in which pixels are arranged in an area and comprises an infrared detector, having a transfer CCD element. Thus, the area of the detector 4 will not grow so much even when the number of pixels of the linear incident end face 2a increases. This facilitates the cooling with a smaller Dewer 5 and the use of a cold shield 6 thereby enabling corresponding to the increase in the number of pixels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared imaging device,
In particular, the present invention relates to an infrared imaging device having a linear light receiving area.

[0002]

2. Description of the Related Art Infrared imaging devices are used in various fields. For example, it is also used in an observation system mounted on a satellite to capture an image showing the temperature distribution on the surface of the earth, transmitting the image signal to an earth station and displaying it on a display.

As an infrared detector of this infrared image pickup device, quantum infrared detector elements arranged in an area are used. The quantum infrared detecting element is, for example, InSb.
(3 to 5 μm light) and HgCdTe (8 to 12 μm light) manufactured using a special compound semiconductor, transfer CCD
Some are formed in combination with.

The infrared detector is 77K (absolute temperature)
Since it is necessary to use it at a very low temperature, it is usually cooled by using a refrigerant such as liquid nitrogen.

Further, it is also necessary to provide a shield immediately before the infrared detector in order to take in only infrared rays from the subject and eliminate extraneous background light (JP-A-60-87).
19 publication).

[0006]

However, when a photoelectric conversion part having a large-scale linear array structure in which 1000 or more infrared detecting elements are linearly arranged is provided, the following difficulties are encountered in manufacturing or actually using the photoelectric conversion part. Occurs.

As described above, the infrared detecting element has an Hg
Since a special compound semiconductor such as CdTe is used as a material, it is difficult to form a large-diameter, uniform crystal, and if a crystal having no defect is to be obtained, the yield will be extremely reduced.

In order to solve this problem, a multi-chip structure in which a plurality of small-scale linear array photoelectric conversion chips are provided and arranged linearly can be considered. However, it is technically very difficult to arrange a plurality of small chips flatly and without gaps, which leads to a reduction in yield and an increase in cost.

A further problem in actually operating the photoelectric conversion unit having a large-scale linear array structure is a cooling measure. For example, as a large-scale linear array structure, 400
When 0 to 10000 infrared detecting elements are arranged on a straight line, the size of the device in the longitudinal direction is about 100 to 5
It becomes 00 mm.

In order to cool the photoelectric conversion part of such a size, a large cooling dewar is required, which causes a decrease in cooling efficiency and an increase in cost. Also, it is difficult to realize an effective cooling shield.

Therefore, an object of the present invention is to provide an infrared image pickup device which can be easily put into practical use even if the number of pixels in the linear light receiving region increases.

[0012]

An infrared imaging device according to the present invention comprises a first imaging optical system for imaging infrared rays from a subject and a plurality of infrared waveguides having an incident end face and an outgoing end face. Infrared waveguide means in which the incident end faces are linearly arranged, the exit end faces are arranged in an area, and the linear incident end face is arranged on the image forming surface of the first image forming optical system; A second image forming optical system for forming an image of infrared rays emitted from the end face; and an infrared detector arranged on the image forming surface of the second image forming optical system and having a plurality of photoelectric conversion elements arranged in an area pattern, It is characterized by consisting of.

[0013]

[Function] The ends of the plurality of infrared waveguides on the incident side are arranged linearly (one-dimensional), and the ends on the emission side are area-shaped (two-dimensional).
To array. Light emitted from the area-shaped emission end face is photoelectrically converted by an area infrared detector.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a general block diagram showing an embodiment of an infrared imaging device according to the present invention.

In the figure, an infrared image forming optical system 1 is composed of an infrared lens and the like, collects infrared rays emitted from various parts of a subject, and makes an incident end face 2a of an infrared fiber bundle 2.
Image on top.

The infrared fiber bundle 2 is composed of infrared fibers of a number (for example, 4000 to 10000) according to the number of pixels. At the incident end surface 2a of the infrared fiber bundle 2,
The end faces of each infrared fiber are linearly arranged to form a linear light receiving surface. The incident end face 2a is arranged at the image forming position (focus position) of the infrared image forming optical system 1. Infrared rays incident from the linear incident end surface 2a pass through each fiber of the infrared fiber bundle 2 to form the area-shaped outgoing end surface 2
Emit from b. The arrangement of the entrance end face 2a and the exit end face 2b will be described later.

The infrared relay optical system 3 is also an imaging optical system, and the infrared rays emitted from the emission end face 2b of the infrared fiber bundle 2 are made incident to form an image on the infrared detector 4.

The infrared detector 4 is an area sensor in which pixels are arranged in an area shape (for example, 100 × 100).
Each pixel is composed of an infrared detection element using HgCdTe or the like as a material for the photoelectric conversion unit, and further a transfer CCD element (described later)
have. The infrared light emitted from the infrared relay optical system 3 forms an image on the infrared detector 4 and is converted into an electric signal according to the amount of light.

Further, the infrared detector 4 is installed in a cylindrical cooling dewar 5 to perform a predetermined cooling. Furthermore,
A cold shield 6 is provided on the infrared detector 4 in order to prevent the incidence of background light other than infrared light incident from the infrared relay optical system 3. In addition, cooling dewar 5
Is cooled with liquid nitrogen.

Next, FIG. 2 shows an arrangement example of the incident end face 2a and the emitting end face 2b of the infrared fiber bundle 2.

FIG. 2A illustrates the incident end surface 2a of the infrared fiber bundle 2. Here, the end faces of 10,000 infrared fibers are linearly arranged. In the drawings, reference numerals 2a-1 to 2a-10000 are numbers corresponding to the infrared fibers.

Infrared fiber bundle 2 constructed in this way
The infrared rays that have entered the incident end surface 2a of (1) pass through each infrared fiber and are emitted from the emitting end surface 2b of the infrared fiber bundle 2.

FIG. 2B illustrates the emission end face 2b of the infrared fiber bundle 2. In line with the above example, 10000
The emission end faces of the two infrared fibers are arranged in a square shape. That is, 2a-1 to 2a at the incident end face 2a.
The infrared fiber indicated by -100 is arranged as the first row (reference numerals 2b-1 to 2b-100) of the emitting end face 2b, and the infrared fiber indicated by 2a-101 to 2a-200 is the second row (2b-101). 2b-200). The same applies hereinafter. Thus, 10 in total
It has a square array of 0 × 100. Of course, it is not limited to such a square array, and it may be appropriately determined according to the number of fibers and the pixel array of the infrared detector.

FIG. 3 is a structural example of the infrared detector 4.

In the figure, the infrared detector 4 is composed of 10000 infrared detector elements and 100 infrared detector elements according to the above example.
It consists of individual transfer CCD elements. The array of the infrared detecting elements is the same as the array of the infrared fibers on the emission end face 2b of the infrared fiber bundle 2, and here, 100 × 100.
It is composed of. That is, the infrared detecting elements 4-1 to 4-
100 are arranged in the first row, and likewise, one row is formed every 100 pieces, and 4-9901 to 4-10000 are the first rows.
It is arranged in the 00th column.

Thus, the emitting end face 2b of the infrared fiber is
The infrared rays emitted from the respective fibers are relayed through the infrared relay optical system 3, and the corresponding infrared detecting elements 4-1 to 4-
Each is incident on 10000 and converted into an electric signal.

A transfer CCD element is provided for each row of infrared detection elements. That is, the infrared detecting elements 4-1 to 4
One transfer CCD 4-1a is provided for -100, and similarly, the infrared detecting elements 4-9901 to 4-1000 are provided below.
0 is provided with a transfer CCD 4-100a.

The CCD 4-1a is an infrared detecting element 4-1.
4 to 100 read in parallel the respective electric signals photoelectrically converted and output in series at a predetermined timing. in this way,
If the CCD 4-1a to CCD 4-100a read the photoelectric conversion signals of the respective columns and sequentially output the photoelectric conversion signals at a predetermined timing, the incident end surface 2a-1 of the infrared fiber bundle 2 will be described.
It is possible to sequentially output the infrared rays incident on the incident end faces 2a-2 to 2a-10000, starting from the electric signal corresponding to the infrared rays incident on. That is, in this example, 100
The same image signal as the signal photoelectrically converted by the 00 pixel line sensor can be obtained.

As described above, as the infrared detector 4, a device in which infrared detecting elements are two-dimensionally arranged can be used. Two
The dimensional infrared detector has been commercialized on a considerably large scale and has been downsized. For example, the array of infrared detection elements is 128 x 128 (about 16000 elements).
The device size of the infrared detector, which is ˜256 × 256 (about 65,000 elements), is realized in a substantially square shape of 10 to 20 mm.

Therefore, even if the number of pixels in the linear array increases, a small cooling dewar 5 for cooling the infrared detector 4 can be used. Cooling dewar 5
The smaller the size, the better the cooling efficiency, which can greatly contribute to cost reduction. Further, since effective cold shielding can be performed on a small area, noise caused by fluctuation of background light is reduced, and the sensitivity of the infrared detector 4 is improved.

The number of fibers forming the infrared fiber bundle is not limited to this embodiment. Further, the arrangement of the infrared fiber bundle on the emitting end face is not limited to the square shape, but may be arranged in an approximate rectangular shape, for example.

Further, it is not necessary to make the number of fibers forming the infrared fiber bundle equal to the number of infrared detecting elements on the infrared detector. That is, the number of infrared detecting elements may be larger than the number of fibers. With such a configuration, when the infrared detector includes a defect detection element, the infrared detection can be performed only by the normal infrared detection element by changing the arrangement on the emitting end face of the infrared fiber bundle. it can.

The emitting end face of the infrared fiber bundle may be divided into a plurality of groups each consisting of an arbitrary number of infrared fibers, and each of them may be detected by a plurality of infrared detectors.

Further, in the present invention, it is possible to perform a time delay operation (TDI) in order to increase the sensitivity of infrared detection.

[0036]

As described above, in the infrared imaging device according to the present invention, the incident side ends of a plurality of infrared waveguides are arranged linearly and the emitting side ends are arranged in an area shape, respectively. The light emitted from is photoelectrically converted by an area infrared detector.

Thus, a linear light receiving area can be realized by using an area infrared detector which is easy to manufacture. Even if the number of pixels in the linear light-receiving area increases, the size of the area infrared detector does not change significantly, so that the device configuration and its change become easy. Further, the area infrared detector can be easily cooled, which is advantageous in cost. Further, since the infrared detector has an area shape, a cold shield that reduces noise caused by fluctuations in background light works effectively, and infrared detection sensitivity is improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an infrared imaging device according to the present invention.

FIG. 2 is a schematic diagram illustrating a fiber arrangement of an incident end face (a) and an emitting end face (b) of an infrared fiber bundle in the present embodiment.

FIG. 3 is a configuration diagram showing a pixel array of an infrared detector of the infrared imaging device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infrared imaging optical system 2 Infrared fiber bundle 2a Incident end face of infrared fiber bundle 2b Outgoing end face of infrared fiber bundle 3 Infrared relay optical system 4 Infrared detector

Claims (3)

[Claims] 1. A first imaging optical system for forming an image of infrared rays from a subject, and a plurality of infrared waveguides having an incident end face and an outgoing end face, wherein the incident end faces are linearly arranged, and the outgoing end face is arranged. Are arranged in an area, and the linear incident end face is arranged on the image forming surface of the first image forming optical system, and an infrared wave guide means for forming an image of infrared rays emitted from the emitting end face. An infrared imaging device comprising: an image forming optical system; and an infrared detector arranged on the image forming surface of the second image forming optical system and having a plurality of photoelectric conversion elements arranged in an area. 2. The infrared imaging device according to claim 1, wherein the infrared wave guide means is a bundle of a plurality of infrared fibers. 3. The infrared imaging apparatus according to claim 1, wherein the emitting end face of each infrared waveguide of the infrared waveguide corresponds to each photoelectric conversion element of the infrared detector.