JPH0886599A - Infrared dome - Google Patents

Abstract

PURPOSE: To prevent transmission of electromagnetic waves in an infrared dome used for an infrared homing flight body. CONSTITUTION: A head 1 of a flight body is covered by an infrared dome substrate 2 with an optical coating 3a applied to an outside of the substrate and an optical coating 3b applied to an inside of the substrate. Further, a surface of the optical coating 3b is coated with an electrically conductive coating 4 in a meshy manner. An infrared dome 10 of the above constitution almost transmits infrared rays therethrough but the meshy electrically conductive coating 4 blocks electromagnetic waves. So, an interior of the dome is prevented from being affected by electromagnetic waves, and generation of radar echo due to reflection by metallic parts in the interior of the dome is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared dome used for an infrared guided vehicle.

[0002]

2. Description of the Related Art Conventionally, in an infrared induction device, a dome is provided on the head of a flying body equipped with an electronic device for guiding and detecting infrared rays, and the infrared rays permeate the dome to guide the infrared rays to a detecting section. It is like this. Since the flying body guided by infrared rays is naturally placed in an environment where electromagnetic waves are irradiated, the infrared dome receives electromagnetic waves.

Since such an infrared dome needs to transmit infrared rays and guide the infrared rays, an optical reflection coat is provided on the dome base material for the purpose of improving the infrared transmittance of the dome.
DLC (Diamond Like Carbon) coating was applied to both outer surfaces and for the purpose of improving mechanical properties (surface hardness).

[0004]

Such a conventional infrared dome is used under the environment where various electromagnetic waves are irradiated as described above. The base material used for the infrared dome and the above-mentioned optical reflection coating are used. Does not have a function of shielding electromagnetic waves, and under the circumstances where electromagnetic waves are radiated, the electromagnetic waves reach the inside of the infrared dome and reach. When electromagnetic waves penetrate into the dome, the following problems occur.

(1) An unfavorable influence (electromagnetic interference) occurs on the electronic equipment inside the infrared dome.

(2) When radar radio waves are radiated and pass through the dome, a large radar echo is generated by the metal parts inside the dome. This is the detection rate by the radar as much as possible,
It is disadvantageous when it is used for the intended use.

[0007]

In order to solve such problems, the present invention provides a structure in which an infrared dome is coated with a conductive film in a mesh shape to prevent the transmission of electromagnetic waves into the dome. To do. Furthermore, a structure for providing the conductive film by vapor deposition is also provided.

That is, the present invention provides (1) an infrared dome having a dome base material for covering a head of a flying body and an optical coat applied to an outer surface and an inner surface of the base material. Provided is an infrared dome, characterized in that the surface of an inner optical coat is coated with a mesh-shaped conductive film.

(2) In an infrared dome having a dome base material for covering the head of a flying body and an optical coat applied on the outer and inner surfaces of the base material, the inner optical coat There is also provided an infrared dome characterized in that a mesh-shaped conductive film is deposited on the surface.

[0010]

According to the present invention, according to the above-mentioned means, the infrared rays transmitted through the infrared dome in the invention of (1) are slightly attenuated by the mesh-like conductive film coated on the substrate, but most of them are transmitted and originally Infrared detection is performed.
On the other hand, this mesh-shaped conductive film acts as an electromagnetic shield against an incoming electromagnetic wave and can considerably attenuate the electromagnetic wave reaching the inside of the infrared dome. Therefore, it is possible to prevent electromagnetic interference in the electronic device in the infrared dome due to this electromagnetic wave and radar echo due to reflection of the electromagnetic wave by the metal parts inside the dome.

Further, also in the invention of (2), since the conductive film is applied by vapor deposition, the same action and effect as in (1) can be obtained, and the conductive film can be molded accurately and surely. Is.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of an infrared dome according to a first embodiment of the present invention and a second embodiment to be described later, FIG. 2 is a detailed partial enlarged view thereof, and FIG. 3 is a view of the surface of its conductive coat,
FIG. 4 is a partially enlarged view of FIG.

In FIGS. 1 and 2, 1 is a head of a flying body, and this head 1 is an infrared dome substrate 2 made of ZnS.
Covered with. For the purpose of improving the optical characteristics of the base material 2, the optical coat 3 is formed on the base material 2 like 3a and 3b.
It is given to the outside. Further, a conductive coat 4 containing a conductive metal is applied to the surface of the inner optical coat 3b to form an infrared dome 10. In the first embodiment, as shown in FIGS. 1 to 4, inside the infrared dome 10, a conductive coat is further applied to the surface of the optical coat 3b applied to the substrate 2, as shown in FIG. The coating is applied in a mesh shape such as the space L, or the like.

Next, a second embodiment of the present invention will be described. In the second embodiment, a conductive coat is applied as shown in FIGS. 3 and 4 described above, but gold (Au) is used as the material of the conductive coat and this is vapor-deposited in a mesh shape. is there. In this case, when the mesh interval L is 1 mm and the line width W is 0.14 mm, the electromagnetic shield effect is 26 dB.
(10 GHz), and the infrared transmittance is 73% as compared with the case where Au is not vapor-deposited.

As described above, by coating or vapor-depositing a conductive metal on the inside of the infrared dome 10, the original purpose of the infrared dome is not to prevent the transmission of infrared rays and the effect of shielding electromagnetic waves. It is possible to make them compatible.

FIG. 5 is a characteristic diagram showing the relationship between the conductive coat and the infrared transmittance when the conductive coat is applied in a mesh shape as described above. In the figure, 20 is the calculated value of the mesh spacing and infrared transmittance when the line width of the conductive coat is 0.1 mm, 0.2 mm and 0.3 mm, and 21 is Z
Measured values of a specimen (line width 0.13 mm) 1 and a specimen (line width 0.15 mm) 2 in which Au was vapor-deposited on an nS base material with a mesh interval of 1 mm, 22, 23, and 24 were metallic on the ZnS base material, respectively. It is a measured value when meshes (line width 0.27 mm, 0.16 mm, 0.09 mm) are overlapped.

From the results shown in FIG. 5, it is found that the measured values substantially match the trial calculated values, and the infrared transmissivity is improved by increasing the mesh interval, and the interval is made constant to narrow the line width. Therefore, the transmittance can be improved.
Therefore, if the required value of the infrared transmittance is determined, the mesh interval and the line width of the conductive coat that satisfies the required value can be determined.

FIG. 6 is a diagrammatic characteristic showing the relationship between the electroconductive coating and the radio wave transmittance when the electroconductive coating is applied in a mesh shape. In the figure, 30 is the calculated value of the mesh interval and the radio wave transmittance when the line width of the conductive coat is 0.1 mm, 0.2 mm and 0.3 mm, and 31 is Au deposited on the ZnS base material. The measured values of the same specimens 1 and 2 as in FIG.
32, 33, and 34 are the measured values when the wire net is overlaid on the base material as in FIG.

From the results shown in FIG. 6, the measured values are almost in agreement with the calculated values, and the radio wave transmittance is reduced when the mesh interval is narrowed, and is reduced when the line width is increased. Is something that can be done. Therefore, if the design required value of the radio wave transmittance is determined, the mesh interval and the line width of the conductive coat that satisfies the required value can be determined.

On the other hand, the original purpose of the infrared dome is to transmit infrared rays and shield electromagnetic waves as described above. However, as shown in FIGS. 5 and 6, the infrared transmittance and the electromagnetic shield effect are different from each other. , The relationship between the mesh interval and the line width is inverse to each other, and therefore the infrared detection capability is determined to the extent that the infrared induction function is not hindered,
In this allowable range, the infrared transmittance must be lowered to some extent to reduce the radio wave transmittance.

This condition will be described with a specific example. Now, the infrared transmittance is 10 because the conductive coat is provided in a mesh shape.
If it is reduced from 0% to K%, the detection distance of the infrared guiding device will be shortened by about the following formula.

[0022]

[Equation 1]

Now, assuming that there is no conductive mesh, 15
Assuming that the presence of the mesh reduces the infrared transmittance to 80% even if there is a detection distance of km, K = 80 in the above equation, and the detection distance is from 15km to 13.9km.
It will be reduced to 14.6km, and no other problems will occur. If the detection distance is reduced to this extent, it can be sufficiently covered by increasing the accuracy of the other parts of the system, that is, the INE, the rating device, etc., so that the infrared transmittance can be reduced.

Therefore, as described above, if the infrared transmittance is determined to be 80%, the mesh spacing and line width of the conductive coat that meet the required values are determined from the characteristic data shown in FIG. 5, and According to FIG. 6, the radio wave transmittance under that condition is determined, and the radio wave transmitted through the infrared dome can be reduced accordingly. Also, conversely, this value is determined by emphasizing the decrease in radio wave transmittance, and the mesh interval and line width are determined.
It is also possible to make the infrared transmittance suitable for it.

According to the first and second embodiments, the optical coat 3b on the inner side of the infrared dome 10 is described as described in the above-mentioned specific example.
By applying the conductive coat 4 as shown in FIGS. 3 and 4 on the surface of the metal with a mesh interval and a line width that meet the required value of the infrared transmittance or the radio wave transmittance, the infrared transmission is not hindered and the electromagnetic wave is prevented. It is possible to realize an infrared dome that satisfies both of the requirements of shielding.

[0026]

As described above in detail, according to the present invention, a conductive film is coated or vapor-deposited on the inner side of the infrared dome to form a mesh shape.
Since it is possible to transmit infrared rays inside the infrared dome and prevent the transmission of electromagnetic waves, it is possible to give an electromagnetic shield effect inside the dome, thereby reducing electromagnetic interference of external radio waves to devices inside the infrared dome, and It is possible to reduce the large radar echo caused by the metal parts of.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an infrared dome according to first and second embodiments of the present invention.

FIG. 2 is a detailed partial enlarged view of the cross-sectional view in FIG.

FIG. 3 is a diagram showing a part of the surface of the conductive coat according to the first and second embodiments of the present invention.

FIG. 4 is a detailed partial enlarged view of FIG.

FIG. 5 is a characteristic diagram of infrared transmittance in the conductive coat according to the first and second examples of the present invention.

FIG. 6 is a characteristic diagram of radio wave transmittance in the conductive coat according to the first and second embodiments of the present invention.

[Explanation of symbols]

 1 Flying Head 2 Infrared Dome Base Material 3 Optical Coat 4 Conductive Coat 10 Infrared Dome 20 Calculated Infrared Transmittance 21 Specimen 22 Measured Infrared Transmittance with Wire Mesh 1 23 Infrared Transmittance with Wire Mesh 2 Measurement value 24 Measured value of infrared transmittance in wire net 3 30 Calculated value of radio wave transmittance 31 Specimen 32 Measured value of radio wave transmittance in wire net 1 33 Measured value of radio wave transmittance in wire net 2 34 Wire net 3 Measurement value of radio wave transmittance of

Claims (2)

[Claims] 1. A dome base material for covering the head of a flying object,
An infrared dome having an outer surface and an inner surface coated with an optical coat, wherein the surface of the inner optical coat is coated with a mesh-shaped conductive film. 2. An infrared dome comprising a dome base material for covering the head of a flying object and an optical coat applied to the outer and inner surfaces of the base material, wherein a mesh is formed on the surface of the inner optical coat. An infrared dome characterized by being formed by vapor-depositing a sheet-shaped conductive film.