JPH0449786B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a cooling type photoelectric conversion device, and in particular to a phenomenon of shedding of the amount of light incident on an array of infrared light receiving elements arranged two-dimensionally on a cooling head in the device. It concerns the structure of the cold shield, which can be significantly reduced.

(b) Background of the Technology Photoelectric conversion elements for infrared detection, which are generally made of semiconductors, produce an output that corresponds to the amount of incident light, and they have the property of not operating well unless they are cooled to a temperature much lower than room temperature. Therefore, for example, the photoelectric conversion element can be stored in the vacuum using a vacuum insulated container with a dewar structure consisting of an outer cylinder partially provided with an infrared transmitting window and an inner cylinder provided with a cooling head opposite the infrared transmitting window. It is installed on a cooling head on the vacuum side inside a heat insulating container, and is operated by cooling it to a predetermined low temperature (for example, 77°K) using liquid nitrogen or the like via the cooling head.

On the other hand, the viewing angle for the photoelectric conversion element depends on the shape of the field-of-view determining opening in the cold shield provided on the front of the element, which defines the range of incident light, and the distance between the opening and the element's light-receiving surface. It is determined that

This cold shield is further cooled to the extremely low temperature together with the photoelectric conversion element to prevent background radiation from entering outside the detection field of view.

(c) Prior Art and Problems By the way, as a cold shield for a conventional multi-element infrared sensing element, for example, an infrared receiving element array having a two-dimensional arrangement, for example, the arrangement pitch of each light receiving element of the infrared receiving element array is Since the field of view is usually extremely small, ranging from several μm to several tens of μm, it is necessary to provide a separate field-of-view determining aperture corresponding to each light-receiving element (see Figure 2 of JP-A-57-142526). ) is difficult in terms of manufacturing and structure, so as shown in the schematic perspective view of FIG.
A cold shield 3 having, for example, a square field-of-view determining opening 4, facing the entire light-receiving surface of the
The openings 4 are arranged in parallel and spaced apart by a predetermined distance.

However, cold shield 3 as mentioned above
Regarding the shape of the field-of-view determining opening 4, the effective viewing angles of the light-receiving elements 2a at the center and the light-receiving elements 2b at the peripheral ends of the light-receiving element array 1 are different.

That is, so-called shading occurs in which the amount of light incident on the light-receiving element array 1 decreases from the center toward the peripheral edge of the array.
This caused an inconvenience. As a result, the signal output of each of the light receiving elements 2 becomes non-uniform, resulting in a configuration similar to that of arranging light receiving elements 2 whose sensitivity decreases from the center toward the peripheral edge. This caused an undesirable phenomenon.

Therefore, by increasing the distance between the light-receiving surface of the light-receiving element array 1 and the field-of-view determining opening 4 of the cold shield 3, the shedding phenomenon can be reduced. The drawback was that the structure became larger and the device became larger.

(d) Object of the Invention In view of the above-mentioned conventional drawbacks, the present invention improves the shape of the field-of-view determining opening of the cold shield with respect to the entire light-receiving element surface of an infrared light-receiving element array having a two-dimensional arrangement. An object of the present invention is to provide a novel cooled photoelectric conversion device that equalizes the effective viewing angle on each light-receiving element surface of an infrared light-receiving element array, thereby eliminating the shudder phenomenon that occurs on all light-receiving element surfaces. It is.

(e) Structure of the Invention According to the present invention, this object includes a cold shield provided with an opening for determining the field of view that defines the range of incident light in front of the infrared receiving element array arranged in two dimensions. A light-shielding partition plate having a predetermined width and having a surface perpendicular to the light-receiving surface of the light-receiving element array is disposed in the opening of the cold shield in the form of a mesh, and the size of the mesh formed by the partition plate and This is achieved by providing a cooled photoelectric conversion device characterized in that the viewing angle of each light-receiving element is made constant by the width of the light-shielding partition plate and the installation height of the light-receiving element from the light-receiving surface. Ru.

(f) Invention and Examples Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic perspective view showing one embodiment of the structure of the opening of the cold shield in the cooled photoelectric conversion device according to the present invention.

As shown in FIG. 2, in the present invention, a cold shield is arranged two-dimensionally on a cooling head (not shown) and faces the entire light receiving element surface of the infrared receiving element array 1 at a predetermined height. The shape of the field-of-view determining opening 4 in No. 3 is, for example, such that a light-shielding partition plate 22 having a surface perpendicular to the light-receiving surface 2c of the light-receiving element array 1 is provided in the opening 4, and has a lattice shape as shown in the figure. The structure is such that they are arranged in a mesh pattern.

However, in this case, each mesh portion 23 formed by the light-shielding partition plate 22 does not need to correspond to the opposing light-receiving element array 1 and each light-receiving element 2 surface, and the light-receiving portions of the light-receiving element array 1 Element 2
A configuration is adopted in which an arbitrary number of mesh portions 23 smaller than the number of mesh portions 23 are opposed to each other.

The mesh light-shielding partition plate 21 arranged in the field-of-view determining opening 4 of the cold shield 3 as described above.
, the width L of each light-shielding partition plate 22, and the width L of each light-shielding partition plate 22.
By appropriately selecting the distance D between the meshes and the height H of the mesh light shielding partition plate 21 with respect to the two surfaces of the light receiving elements, the effective viewing angle at each light receiving surface 2c of the light receiving element array 1 can be adjusted to The light-shielding partition plates 21 arranged in a shape make it possible to define extremely evenly.

Therefore, the shedding phenomenon in which the amount of light incident on the light receiving element array 1 decreases from the central light receiving element 2a toward the peripheral end light receiving element 2b can be significantly reduced.

Note that in the above embodiment, an example was explained in which a lattice-type mesh light-shielding partition plate 21 was disposed in the opening 4 of the cold shield, but the present invention is not limited to this, and for example, As shown in FIG. 3, there is a mesh light-shielding partition plate 31 in which the mesh portion 23 is shaped like a diamond, or as shown in FIG. As shown in the figure, the mesh portion 23
It goes without saying that various modifications can be made as necessary, such as the mesh light shielding partition plate 51 having a hexagonal shape.

(g) Effects of the Invention As is clear from the above description, according to the cooled photoelectric conversion device of the present invention, the cold shields arranged opposite to all the light receiving element surfaces of the infrared light receiving element array having a two-dimensional arrangement are Since the field-of-view determining opening has a structure in which light-shielding partition plates having surfaces perpendicular to the light-receiving surface of the light-receiving element array are arranged in a mesh pattern, each light-receiving element surface of the light-receiving element array This has the advantage that the effective viewing angle can be uniformly defined, and the conventional shading phenomenon is significantly reduced.

Therefore, uniform output signals can be obtained across each light receiving element, and the performance of the cooled photoelectric conversion device can be greatly improved. It also has excellent advantages, such as the ability to make the cold shield compact.

[Brief explanation of the drawing]

Figure 1 shows a conventional cooling type photoelectric conversion device.
FIG. 2 is a schematic perspective view illustrating the structure of the opening of the cold shield; FIG. Figure, 4th
5 are conceptual diagrams showing other embodiments of the mesh-like light-shielding partition plate disposed in the opening of the cold shield in the cooling type photoelectric conversion device according to the present invention. In the drawings, 1 is an infrared receiving element array; 2 is an infrared receiving element array;
is a light receiving element, 2a is a central light receiving element, 2b is a peripheral edge light receiving element, 2c is a light receiving surface, 3 cold.
shield, 4 is an opening for determining visual field, 21, 31;
Reference numerals 41 and 51 indicate mesh-like light-shielding partition plates, 22 indicates a light-shielding partition plate, and 23 indicates a mesh portion.

Claims (1)

[Claims] 1. A cold shield 3 is provided in front of the infrared receiving element array 1 arranged two-dimensionally, and has an opening 4 for determining the field of view that defines the range of incident light. The light-shielding partition plates 22 having a predetermined width and having a surface perpendicular to the light-receiving surface 2c of the light-receiving element array 1 are arranged in a mesh pattern, and the size of the mesh formed by the partition plates 22 and the width of the light-shielding partition plate 22 are and the light receiving surface 2c of the light receiving element 2
1. A cooling type photoelectric conversion device characterized in that the viewing angle of each light receiving element 2 is made constant depending on the installation height from above.