JPH06322520A - Separating plate of radio wave and infrared ray and production thereof - Google Patents

Abstract

PURPOSE:To provide a separating plate of radio wave and infrared ray having the function of separating the radio wave and the infrared ray by allowing to transmit the radio wave and reflect the infrared ray and to provide the production method thereof. CONSTITUTION:For example, the infrared ray reflecting film 4 is formed by laminating alternately a germanium layer 2 and a rare earth metal fluoride layer 3 in this order on the one surface of the dielectric substrate 1 consisting of e.g. quartz glass. And, the separating plate 21 of radio wave and infrared ray is produced by laminating the germanium layer 2 and the rare earth metal fluoride layer 3 by electron beam deposition while heating the substrate 1 at 130-250 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separating plate for radio waves and infrared rays. More specifically, the present invention relates to a separation plate for separating radio waves and infrared rays by transmitting radio waves and reflecting infrared rays, and a method for manufacturing the same.

Radio waves have a lower frequency than infrared rays,
It refers to electromagnetic waves used in telecommunications, especially microwave and millimeter wave electromagnetic waves.

[0003]

2. Description of the Related Art Recently, radars and infrared detectors provided in defense equipments such as aircrafts, missiles, ships, and tanks have been improved in performance, and various components are included in them. The ability to cross is required. For example, the compounding of the detection device is one of them. By integrating the detection system by radio waves and the detection system by infrared rays, it is possible to significantly improve the detection performance and the anti-interference property. It is necessary to separate the reflected radio wave, which is the signal from the target object, and the radiated infrared light and detect them by their respective detectors.

Separation of radio waves and infrared rays for realizing the above-mentioned composite detection system is carried out, for example, by transmitting radio waves and reflecting infrared rays. Conventionally, radio waves are transmitted by transmitting such radio waves and reflecting infrared rays. As a technology for separating infrared rays from infrared rays, by applying infrared filter technology, a dielectric material that does not absorb radio waves is used as a substrate, and a dielectric material or a semiconductor material is used to perform coating that highly reflects infrared rays. They are separated by being transmitted without being reflected and reflecting infrared rays. This coating for highly reflecting infrared rays is described, for example, on pages 191 to 217 of "Optical Thin Film" (published by Nikkan Kogyo Shimbun, 1989) by HAMacleod (translated by Ogura, Nakajima, Yabe, Yoshida). As described above, the high refractive index substance and the low refractive index substance are realized by alternately laminating the optical film thickness of λ / 4, where λ is the wavelength of infrared rays to be reflected. Here, the optical film thickness refers to the actual film thickness × refractive index of a substance with respect to electromagnetic waves of wavelength λ. Assuming that the refractive index of the high refractive index material is n _H , the refractive index of the low refractive index material is n _L , the refractive index of the substrate is n _S , and the number of layers is 2p + 1 (p is a natural number), the infrared reflectance R is

[0005]

[Equation 1] Is expressed as

The optical film thickness of each layer of the infrared reflecting film is λ.
In the case of / 4, the wavelength band λ ± Δλ with high reflectance is

[0007]

[Equation 2] Is expressed as That is, the larger the number of stacked layers and the larger the refractive index ratio between the high refractive index substance and the low refractive index substance, the higher the reflectance,
Further, the larger the refractive index ratio, the wider the wavelength band having high reflectance.

[0008]

However, when the wavelength is
As a coating material for infrared rays in the vicinity of 10 μm, a high refractive index substance generally has a refractive index of 4
Is often selected, and zinc sulfide (ZnS) having a refractive index of 2.2 is often selected as the low refractive index material.
Zinc sulfide has a problem that its refractive index is not so small.

In order to solve the above problems, calcium fluoride (CaF ₂ ) and cryolite (Na ₃ AlF ₆ ) having a small refractive index of 1.4 are sometimes used, but they have hygroscopicity. , There is a problem in moisture resistance.

Further, as a substrate for an infrared filter having a wavelength of about 10 μm, germanium, zinc sulfide, zinc selenide (ZnSe), calcium fluoride (JP-A-63-151)
No. 904 and Japanese Patent Laid-Open No. 64-80906) are used, but these materials are not only generally expensive, but also processed into a desired thickness or processed into a desired shape. In addition, there is a problem that the workability is poor and a lot of man-hours are required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a separating plate for radio waves and infrared rays, which is excellent in infrared reflectivity and substrate workability, and a manufacturing method thereof. To do.

[0012]

According to the separator for radio waves and infrared rays of the present invention, an infrared reflecting film for transmitting radio waves and reflecting infrared rays is provided on one surface of a dielectric substrate, and the infrared reflecting film is made of germanium. The rare earth fluoride and the rare earth fluoride are alternately laminated in this order.

The rare earth fluoride is preferably cerium fluoride or a mixture of rare earth fluorides containing 50% by weight or more of cerium fluoride.

Further, it is preferable that the infrared reflective film is formed by alternately stacking germanium and rare earth fluoride in this order in an odd number of times of 5 or more and 21 or less.

Further, the respective optical film thicknesses of the germanium layer and the rare earth fluoride layer of the infrared reflection film are set to λ / 4 where λ is the wavelength of infrared light to be reflected, and at least two kinds of reflection films having infrared wavelengths are formed. It is preferably laminated.

The dielectric substrate is preferably made of quartz glass or glass containing 20% by weight or more of quartz glass.

Further, with respect to the thickness of the dielectric substrate, the relative permittivity of the dielectric substrate is ε, and the wavelength of the radio wave to be transmitted is Λ,
It is preferably set to be an integral multiple of Λ / (2ε ^1/2 ).

Further, the method for producing a separating plate for radio waves and infrared rays according to the present invention is an infrared reflecting film in which a germanium layer and a rare earth fluoride layer are alternately laminated in this order on one surface of a dielectric substrate by electron beam evaporation. A method for producing a separating plate for radio waves and infrared rays, which comprises: forming the germanium layer and the rare earth fluoride layer while heating the dielectric substrate to 130 to 250 ° C.

[0019]

In the separation plate for radio waves and infrared rays according to the present invention, since the surface of the dielectric substrate is coated with the germanium layer and the rare earth fluoride layer alternately in this order, the difference in the refractive index between the two layers is prevented. It can be increased, a reflectance higher than that of the formula (1) can be obtained, and radio wave transmission is excellent, so that radio waves and infrared rays can be efficiently separated. Moreover, the rare earth fluoride has excellent moisture resistance, and a highly reliable separator can be obtained.

If a rare earth fluoride or a mixture of rare earth fluorides containing 50% by weight or more of cerium fluoride is used as the rare earth fluoride, it can be obtained at low cost and is easy to handle.
It is possible to easily obtain the separating plate having the above characteristics.

Further, when germanium and rare earth fluoride are alternately laminated in an amount of 5 to 21 in an odd number of times as the infrared reflecting film, it is possible to prevent the occurrence of cracks in the laminated film and reduce reliability. In addition, the reflectance of infrared rays is further improved.

The optical film thicknesses of the germanium layer and the rare earth fluoride layer of the infrared reflecting film are set to λ / 4, where λ is the wavelength of the infrared ray to be reflected, and at least two types of infrared wavelengths are reflected. When the films are laminated, the reflectance is large in a wide range of infrared wavelength band.

Further, when the dielectric substrate is made of quartz glass or glass containing 20% by weight or more of quartz glass, the cost of the substrate can be reduced, the workability is excellent, and the substrate has a precise and predetermined thickness. Radio wave transmission characteristics are improved.

Further, with respect to the thickness of the dielectric substrate, the relative permittivity of the dielectric substrate is ε, and the wavelength of the radio wave to be transmitted is Λ,
By setting it to be an integral multiple of Λ / (2ε ^1/2 ), the phase of the radio wave directly emitted from the dielectric substrate matches the phase of the radio wave emitted by multiple reflection, and the non-reflection condition of the radio wave is satisfied. , With excellent radio wave transparency.

Further, since the method for producing the separating plate for radio waves and infrared rays according to the present invention is carried out while heating the substrate at 130 to 250 ° C. when laminating the infrared reflecting film by electron beam vapor deposition, even a rare earth fluoride layer is used. It can be laminated without causing peeling or cracks, resulting in a multilayer film having excellent adhesion and moisture resistance.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a radio wave and infrared ray separating plate of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing the structure of a radio wave / infrared ray separating plate according to an embodiment of the present invention, and FIG. 2 is a vacuum vapor deposition apparatus used for manufacturing the radio wave / infrared ray separating plate of the present invention. FIG. 3 is a configuration diagram for investigating the radio wave transmission characteristics of the separation plate for radio waves and infrared rays.

As shown in FIG. 1, the separation plate 21 for radio waves and infrared rays according to the present invention is provided with an infrared reflection film 4 on a dielectric substrate 1 which transmits radio waves, and the infrared reflection film 4 is a germanium layer. 2 and a rare earth fluoride layer 3 are laminated.

Any material can be used as the dielectric substrate 1 as long as it can transmit radio waves without loss and can hold the infrared reflection film 4, and a glass substrate, a ceramic substrate or the like can be used. (1) Surface The adhesion of the rare earth fluoride layer 3 of the infrared reflective film 4 coated on the substrate is good. (2) From the above formula (1), in order to increase the reflectance, the refractive index n _s of the dielectric substrate 1 is The glass substrate is preferably used from the viewpoints that the larger the size, the better, (3) the glass has good workability, high dimensional accuracy can be obtained, and a highly reliable product can be easily obtained. Among the glass, silicon dioxide has a relative permittivity of 3.2 to 3.4, which is smaller than that of other components, and has good radio wave transmission, and also has a geometrical thickness with respect to the preferable optical thickness of the substrate described below. Quartz glass containing silicon dioxide as a main component or a glass substrate having a silicon dioxide content of at least 20% by weight or more is particularly preferable because it can be thickened and is easily processed.

The thickness of the dielectric substrate 1 is preferably set to a thickness that allows radio waves to pass through as easily as possible. That is, the radio wave incident from the infrared reflecting film 4 side is hardly absorbed by the infrared reflecting film 4 and the dielectric substrate 1, and the dielectric substrate 1
Although it is emitted from the side, when it is emitted from the dielectric substrate 1 into the air, it is partially reflected and returned, and is reflected again at the interface with the infrared reflection film 4 and emitted from the dielectric substrate 1. If the phase of this radio wave is not canceled by combining it with the phase of the radio wave that is directly emitted, the transmittance can be improved, so when the wavelength of the radio wave is Λ and the relative permittivity of the dielectric substrate is ε, the dielectric The thickness of the substrate is preferably Λ / (2ε ^1/2 ) or an integral multiple thereof.

The infrared reflection film 4 is formed by alternately stacking a germanium layer 2 and a rare earth fluoride layer 3 with an optical film thickness of λ / 4 (λ is the wavelength of infrared rays reflected), and the number of layers is odd. It is a layer, and both ends are formed of a germanium layer. From the above formula (1), the larger the number of laminated layers, the higher the reflectance, which is preferable. However, if the number of laminated layers is too large, cracks are likely to occur in the film, and therefore, the number of layers is about 21 in terms of manufacturing.
Regarding the lower limit, as shown in each of the specific examples described later, by forming the layer with five layers, it is possible to obtain a sufficient reflectance of infrared rays for separating the radio waves and the infrared rays. That is, the number of laminated infrared reflective films is preferably 5 to 21.

In the infrared reflecting film 4 of the present invention, a rare earth fluoride layer 3 is used as a low refractive index layer. Since the rare earth fluoride layer 3 has a small refractive index of about 1.4 and is excellent in moisture resistance, it is a stable film and has a high reflectance. On the other hand, when the rare earth fluoride layer 3 is coated to form an alternate multilayer film with germanium, there is a manufacturing problem that peeling or cracking easily occurs. This problem was solved by heating the dielectric substrate to 130 to 250 ℃.

As the rare earth fluoride, cerium fluoride or a mixture of rare earth fluorides containing 50% by weight or more of cerium fluoride is preferable because it is inexpensive and easily available, but other lanthanum fluoride, praseodymium fluoride, neodymium fluoride are preferable. , Rare earth fluorides such as samarium fluoride, europium fluoride, gadolinium fluoride, terbium fluoride, dysprosium fluoride, holmium fluoride, erbium fluoride, ytterbium fluoride or mixtures thereof with a refractive index of about 1.45 to 1.6. , Can be used as well.

Next, a method for forming a laminated body of the infrared reflecting film 4 will be described.

FIG. 2 is an explanatory view showing a vapor deposition apparatus for manufacturing the separating plate for the radio wave and the infrared ray. In FIG. 2, 4 is a vacuum container for obtaining a high vacuum, and 5 is a substrate mounting dome on which the dielectric substrate 1 is mounted, which is rotated during vapor deposition to improve the uniformity of the film. The dielectric substrate 1 attached to the substrate mounting dome 5 is heated by the heater 7. Reference numeral 8 is a crucible for containing a vapor deposition material, and a crucible 8 containing a substance to be vapor deposited by the crucible rotating stage 9.
Are moved to a position where the electron beam emitted from the electron gun 10 hits. The substance heated and evaporated by the electron beam is deposited on the surface of the dielectric substrate 1 to form a film. The thickness of this vapor-deposited film was measured by measuring the film thickness of the glass substrate 12 for monitoring with a reflection type optical film thickness meter 11 mounted above the vacuum container 4, and became the required thickness. When closing shutter 13. Thereafter, similarly, vapor deposition films of different layers are sequentially formed to have a predetermined thickness.

When forming the above-mentioned multilayer film of germanium and rare earth fluoride, by heating the dielectric substrate 1 to 130 to 250 ° C., more preferably 160 to 180 ° C., peeling or cracking occurs. It is possible to obtain a multi-layered film that is excellent in adhesiveness and moisture resistance. This is because the internal stress generated in the film is minimized by heating.
If the temperature is lower than 0 ° C, the film peels off and the film cannot be formed.

Next, a method of inspecting the separation characteristics of the radio wave and infrared ray separation plates will be described. The separation characteristics are determined by measuring the amount of transmission of radio waves that pass through the separation plate and the reflectance of infrared rays reflected by the separation plate, and the greater the amount of transmission of radio waves and the greater the reflectance of infrared rays, the better the separation characteristics. Is based on. Due to the balance with other optical elements in the infrared optical system, this reflectance is at least 90% or more for wavelengths of 8 to 12 μm, 3 to 5 μm and 8 to 12 μm.
For a wide range of wavelengths of m, it is desirable that it is 80% or more.

FIG. 3 is a view showing the arrangement of an apparatus for examining the radio wave transmissivity of the separation plate for radio waves and infrared rays. The separation plate 21 for radio waves and infrared rays is provided between the transmitting antenna horn 14 and the receiving antenna horn 15. Put. With transmitter 17 and receiver 18,
For the radio wave of constant output, when the separation plate 21 is not inserted, by measuring the change in the received power by the receiver 18 when the separation plate 21 is inserted, the attenuation rate due to the insertion of the separation plate can be determined. It was measured. The transmission frequency of the transmitter was 94 GHz. The transmittance of this electromagnetic wave is preferably −0.5 dB or more from the gain characteristics of the antenna.

The infrared reflectance was measured with a Fourier transform infrared spectrophotometer (trade name, manufactured by Horiba Ltd.) using an aluminum mirror as a reference (infrared reflectance of 98%).

The moisture resistance of the separating plate for radio waves and infrared rays is 50 ° C. when the separating plate is placed in a high temperature and high humidity tank.
After 48 hours of exposure to a humidity of 95% or higher, the coated surface was visually observed to check for stains, cloudiness, peeling, and the like.

Next, more detailed description will be given with reference to specific examples.

[Example 1] The thickness of the dielectric substrate 1 was 1.73.
Using a glass substrate made of quartz glass of mm, the infrared reflection film 4 has a temperature of the substrate 1 of about 180 ° C., and a germanium layer 2 and a rare earth fluoride layer 3 made of cerium fluoride are optically formed by an electron beam evaporation method. Film thickness is 2.5 μm
5 layers were alternately laminated in this order. The thickness of the quartz glass on the substrate 1 is 1.73
mm is set so that the product of the 1/2 power of the relative permittivity 3.4 of the substrate 1 and the thickness of the frequency of the radio wave (94 GHz) is twice the half of the wavelength 3.2 mm of the radio wave under the non-reflective condition. This is because it is adapted to.

As shown in FIG. 5A, the spectral reflectance of infrared rays by the separating plate 1 shows a high reflectance of 90% or more at the infrared wavelength of 8 to 12 μm, and also allows transmission of 94 GHz radio waves. The rate was -0.3 dB or more. As for the moisture resistance, as a result of examining by the above-mentioned measuring method, stains, cloudiness,
No peeling occurred.

[Embodiment 2] The separator 21 for radio waves and infrared rays has a thickness of 1.47 mm, a quartz content of 64% by weight, an aluminum oxide (Al ₂ O ₃ ) content of 25% by weight, and the rest. is other _{oxides, SiO 2 -Al 2 O 3 -MgO} -Na 2 O
Using a glass substrate 1 made of aluminosilicate glass having the composition of, the temperature of the glass substrate 1 is set to 180 ° C. on the surface thereof as in Example 1, and the electron beam evaporation method described above is used. Content of germanium and cerium fluoride 70% by weight, other rare earth fluorides such as lanthanum fluoride (LaF ₃ ), neodymium fluoride (Nd)
An alternating multilayer film with a mixture having a F ₃ ) content of 30% by weight was formed by stacking 5 layers in this order so that the optical film thickness was 2.5 μm.

The thickness of the glass substrate 1 is 1.47 mm because the relative permittivity of the glass substrate 1 with respect to the frequency of radio waves.
The product of the 1/2 power of 4.7 and the thickness is 1 / 3.2 mm of the wavelength of the radio wave.
This is because it is set to twice the value of 2 so as to meet the non-reflection condition.

Further, even with the same glass composition, the dielectric constant becomes smaller as the content ratio of silicon dioxide becomes higher. Therefore, as described above, the content ratio of silicon dioxide is preferably 20% by weight or more.

The spectral reflectance of infrared rays by this separating plate is the same as in Example 1, and as shown in FIG. 5A, the reflectance of infrared rays at a wavelength of 8 to 12 μm is 90% or more, and the reflectance is high. , 94 GHz radio wave transmittance was -0.4 dB or more. Regarding the moisture resistance, as a result of the above-mentioned measurement method,
No stain, cloudiness or peeling occurred.

[Embodiment 3] As a separating plate 21 for radio waves and infrared rays, as shown in FIG. 4, a dielectric substrate 1 having a thickness of 1.73 is used.
On the substrate 1 made of quartz glass of mm, the temperature of the substrate 1 is set to 180 ° C., and the alternating multilayer film of the germanium layer 2 and the rare earth fluoride layer 3 made of cerium fluoride is formed in this order by the electron beam evaporation. By alternately laminating 7 layers, a separation plate for radio waves and infrared rays was obtained. Of the seven layers, the lower three layers 2a, 3a, 2b have an optical film thickness of 2.5 μm, the fourth cerium fluoride layer 3b has an optical film thickness of 0.8 μm, and the upper three layers 2c, 3c, 2d have optical films. The thickness was 1 μm. The lower three layers 2a, 3a and 2b have a function of having a high reflectance for infrared rays having a wavelength of 8 to 12 μm, and the upper three layers 2c and 3b.
c and 2d have a function of providing a high reflectance for infrared rays having a wavelength of 3 to 5 μm, and the cerium fluoride layer 3b in the middle is an adjustment layer for preventing the effects of both of them from canceling each other out.

As shown in FIG. 6, the reflectance of infrared rays by this separating plate is 90% or more for the infrared rays having a wavelength of 3 to 5 μm, and the infrared rays having a wavelength of 8 to 12 μm. The average reflectance was high at least 80%. In the present embodiment, the reflectance is inferior to the infrared rays having a wavelength of 8 to 12 μm as compared with the first and second embodiments, probably because the number of layers is three layers for the wavelength of 8 to 12 μm. To be By forming a laminated film having an optical film thickness corresponding to the wavelength of infrared rays according to the purpose as in the present embodiment, it is possible to form an infrared reflective film in a wide range. Further, the transmittance of radio waves was -0.4 dB or more, which was the same as that in Example 2. Further, the moisture resistance was examined by the above-mentioned measuring method, and as a result, no stain, cloudiness, peeling or the like occurred.

[Embodiment 4] Separating plate 21 for separating radio waves and infrared rays
As shown in FIG. 1, except that the thickness of the substrate 1 made of quartz glass as the dielectric substrate 1 is 7.8 mm,
It was formed with the same configuration as in Example 1. The thickness of the quartz glass of the substrate 1 is set to 7.8 mm because the product of the relative permittivity of the substrate, 3.74, and the thickness of the substrate is 1/30 of the wavelength of 30 mm of the radio wave with respect to the frequency of the radio wave. This is because it is doubled to meet the non-reflection condition.

The reflectance of infrared rays by this separating plate is the same as that of Example 1, and as shown in FIG.
It shows a high reflectance of 90% or more at 12 μm. In this embodiment, the thickness of the substrate 1 is adjusted so that the transmittance does not decrease when the frequency of the radio wave is 10 GHz, and the oscillation frequency of the transmitter 17 is 10 GHz with the configuration shown in FIG.
As a result of examining the radio wave transmittance, it was -0.25 dB or more, and it was possible to obtain a better transmittance than in the case of 94 GHz. The moisture resistance was examined by the above-mentioned measuring method, and as a result, as in the case of Example 1, no stain, fogging or peeling occurred.

[Comparative Example 1] In order to compare with each of the above Examples, a laminated film of germanium and zinc sulfide was used as the infrared reflecting film 4, and a separating plate for radio waves and infrared rays had a thickness of 1.73 mm.
The optical film thickness is 2.5 μm on the surface of the quartz glass substrate.
In the same manner as in Example 1, germanium and zinc sulfide of Example 1 were alternately laminated in this order to form five layers.

The reflectance of infrared rays by this separating plate is shown in FIG.
As shown in B of Figure 6, the reflectance is 8 μm or 12 μm.
It can be seen that the average wavelength is reduced to about 80% and the average wavelength is also reduced to about 88% from Examples 1, 2 and 4. Further, as a result of examining the moisture resistance by the above-mentioned measuring method, it was confirmed that stains were generated.

[Comparative Example 2] Further, in order to compare with each of the above-mentioned Examples, a laminated film of germanium and calcium fluoride was used as the infrared reflecting film 4, and a separation plate for radio waves and infrared rays was made of quartz with a thickness of 1.73 mm. On the surface of the substrate 1 made of glass, germanium and calcium fluoride each having an optical film thickness of 2.5 μm were alternately laminated in this order in the same manner as in Example 1 to form five layers. As a result, as a result of examining the moisture resistance by the above-mentioned measuring method, it was confirmed that fogging occurred.

[Comparative Example 3] As a method for producing a separation plate for radio waves and infrared rays, when a germanium and cerium fluoride were electron beam evaporated on the surface of a substrate 1 made of quartz glass having a thickness of 1.73 mm, this substrate was used. The temperature of 1 is (A) 70 ℃,
(B) An alternating multilayer film of germanium and cerium fluoride having an optical film thickness of 2.5 μm while being heated at two types at 270 ° C.
5 layers were laminated in this order to form a separating plate for radio waves and infrared rays.

When the substrate temperature of the separation plate for radio waves and infrared rays thus formed is 70 ° C. (A), the cerium fluoride layer peels off during coating,
It was not possible to form an alternating multi-layer film with high reflection of infrared rays. Further, when the substrate temperature was 270 ° C. as in (B), numerous cracks were generated on the coating surface after vapor deposition.

The radio wave transmittances of Examples 1 to 4 described above are summarized in a table as shown in Table 1. The frequency of the radio wave at this time, that is, the transmission frequency from the transmitter 17 is 94 GHz in the first to third embodiments and 10 GHz in the fourth embodiment.
The transmittance was expressed in decibel (dB).

[0057]

[Table 1] As can be seen from Table 1, the radio wave / infrared ray separating plate of the present invention has a radio wave transmittance of −0.5 dB or more even in a frequency range used in a radar of 5 to 110 GHz, and has a high radio wave transparency. You can see that Therefore, it becomes possible to separate the radio wave and the infrared ray by transmitting the radio wave and reflecting the infrared ray by the separating plate for the radio wave and the infrared ray according to the present invention, and a great effect can be obtained in practical use.

[Embodiment 5] In each of the above-mentioned embodiments, cerium fluoride or one containing cerium fluoride as a main component was used as the rare earth fluoride, but instead of these, La was used.
F ₃ (lanthanum fluoride), PrF ₃ (praseodymium fluoride), NdF ₃ (neodymium fluoride), SmF ₃ (samarium fluoride), EuF ₃ (europium fluoride), GdF ₃
(Gadolinium fluoride), TbF ₃ (terbium fluoride), DyF ₃ (dysprosium fluoride), HoF ₃ (holmium fluoride), ErF ₃ (erbium fluoride), Y
Similar effects were obtained using other rare earth fluorides such as bF ₃ (ytterbium fluoride).

[0059]

According to the separating plate for radio waves and infrared rays of the present invention, the germanium layer and the rare earth fluoride layer each have an optical film thickness of λ /
Since the infrared reflective film has a large infrared reflectance and a high moisture resistance because it is alternately laminated so as to have a thickness of 4, the separator plate has a large radio wave transmittance, a low cost, and good separation characteristics. Can be obtained.

Further, by stacking the germanium layer and the fluoride layer by electron beam evaporation while heating the dielectric substrate, an infrared reflection film excellent in adhesion and moisture resistance without peeling or cracking can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a structure of an embodiment of a separation plate for radio waves and infrared rays according to the present invention.

FIG. 2 is an explanatory diagram of a vacuum vapor deposition apparatus used to manufacture the radio wave and infrared ray separation plate of the present invention.

FIG. 3 is a configuration diagram of an apparatus for examining the radio wave transparency of a separation plate for radio waves and infrared rays.

FIG. 4 is an explanatory sectional view showing the structure of another embodiment of the separation plate for radio waves and infrared rays according to the present invention.

FIG. 5 is a diagram showing infrared spectral reflectances of Examples 1, 2, 4 and Comparative Example 1 of the present invention.

FIG. 6 is a diagram showing infrared spectral reflectance in Example 3 of the present invention.

[Explanation of symbols]

 1 Dielectric Substrate 2 Germanium Layer 3 Rare Earth Fluoride Layer 4 Infrared Reflective Film 7 Heater 21 Separating Plate for Radio Wave and Infrared Ray

Claims (7)

[Claims] 1. A dielectric substrate is provided with an infrared reflection film for transmitting radio waves and reflecting infrared rays on a surface thereof, and the infrared reflection film is formed by alternately laminating germanium and rare earth fluoride in this order. With a separation plate. 2. The radio wave / infrared ray separating plate according to claim 1, wherein the rare earth fluoride is cerium fluoride or a mixture of rare earth fluorides containing 50% by weight or more of cerium fluoride. 3. The electromagnetic wave and infrared ray separating plate according to claim 1, wherein the infrared reflecting film is formed by alternately stacking germanium and rare earth fluoride in this order in an odd number of times from 5 to 21 layers. 4. The optical film thickness of each of the germanium layer and the rare earth fluoride layer of the infrared reflecting film is set to λ / 4 where λ is the wavelength of infrared light to be reflected, and at least two types of reflecting films of infrared wavelengths are provided. The separation plate for radio waves and infrared rays according to claim 1, which is laminated. 5. The radio wave / infrared ray separating plate according to claim 1, wherein the dielectric substrate is made of quartz glass or glass containing 20% by weight or more of quartz glass. 6. The thickness of the dielectric substrate is Λ, where ε is the relative permittivity of the dielectric substrate and Λ is the wavelength of the radio wave to be transmitted.
The radio wave / infrared ray separating plate according to claim 1, which is set to be an integral multiple of / (2ε ^1/2 ). 7. A method for producing a separation plate for radio waves and infrared rays, wherein a germanium layer and a rare earth fluoride layer are alternately laminated in this order on the surface of a dielectric substrate by electron beam evaporation to form an infrared reflection film. , The dielectric substrate 130 ~ 250 ℃
A method for producing a separating plate for radio waves and infrared rays, characterized in that the germanium layer and the rare earth fluoride layer are laminated while being heated.