JP2003149434A - Optical film for ir region and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film having the antireflection characteristics in both zones of 3 to 5 μm and 8 to 12 μm wavelengths of IR rays, and to provide an optical film for a beam splitter and a beam splitter to separate IR rays into two wavelength zones of 3 to 5 μm and 8 to 12 μm. SOLUTION: The antireflection film for an IR region having the antireflection characteristics in two zones of 3 to 5 μm and 8 to 12 μm wavelengths in the IR region is obtained by forming a multilayered film from materials selected from Si, Ge, ZnS, ZnSe, metal oxides and metal fluorides on a Ge or ZnS substrate. The optical film for a beam splitter and a beam splitter element to separate light into two zones of 3 to 5 μm and 8 to 12 μm wavelengths are obtained by combining alternately deposited layers of Ge and ZnS, a metal oxide layer and a metal fluoride layer on a ZnS substrate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical film and an optical element in the infrared region.

[0002]

2. Description of the Related Art Infrared detectors and infrared cameras provided for defense equipment such as aircraft, missiles, ships, and tanks have become more sophisticated in recent years. For example, widening the band of the detecting device and multi-banding to detect a plurality of bands are one of them, and the infrared wavelength range (hereinafter referred to as an atmospheric window) in which infrared rays easily pass through the atmosphere (absorption of the atmosphere is small) , Band) 3-5 μm and 8-12
By having the detection ability over both wavelengths of .mu.m or the entire wavelength range of 3 to 12 .mu.m, the detection performance and the anti-interference property can be greatly improved. However, in order to realize these, it is important to improve the transmittance of the lens forming the optical system of the device and the characteristics of the filter.
In the present specification, the wavelength range of 3 to 12 μm is called the infrared range.

In the prior art, for an antireflection film for the infrared region, an antireflection film for the antireflection film only in the wavelength range of 3 to 5 μm of the window of the atmosphere, or a slightly expanded one. Alternatively, there were those aimed at the antireflection effect only within the wavelength range of 8 to 12 μm, those slightly enlarged, and the like. Further, as for filters, there have been long-wavelength transmission filters, short-wavelength transmission filters, bandpass filters, and the like for the purpose of blocking intrusion of infrared rays outside the band.

[0004]

In the prior art as described above, an antireflection film for a lens or window of an optical device in which detection of both wavelength ranges of 3 to 5 μm and 8 to 12 μm is performed by one optical system. It is obvious that it cannot be used. Also for a filter, such an optical system is used as an infrared sensor for a wavelength range of 3 to 5 μm and 8 to 1
Although it often has two types for 2 μm, it separates the incident infrared light of the wavelength range of 3 to 5 μm and 8 to 12 μm into two wavelength bands, and a sensor for the wavelength range of 3 to 5 μm and 8 to 12
It cannot be used as an optical element for branching to the μm sensor. In addition, wavelength range 3-5μ
The optical element for the purpose of splitting into m and two wavelength bands of 8 to 12 μm is hereinafter referred to as a beam splitter. It should be noted that a conventional beam splitter is different from splitting light by utilizing 50% reflection and 50% transmission characteristics for a desired wavelength band.

The present invention has been made to solve the above-mentioned problems, and has a wavelength range of 3 to 5 μm and 8 to 8.
Lens system that transmits both bands of 12 μm and wavelength range 3
For an optical device having two sensors of ˜5 μm and 8-12 μm, an anti-reflection film having excellent anti-reflection characteristics in both wavelength ranges of 3-5 μm and 8-12 μm and a wavelength range of 3-5 μm are reflected. Then, an optical multilayer film for a beam splitter that separates these two bands by transmitting 8 to 12 μm, and a wavelength range of 3.5 to 5 μm,
An object of the present invention is to provide an optical multilayer film for a beam splitter that separates these two bands by reflecting 11 μm, and a beam splitter element. In the present specification, such an optical multilayer film refers to a multilayer film having a property of stacking a plurality of thin films to reflect or transmit light of a specific wavelength. In the latter optical multilayer film for a beam splitter, the wavelength range is set to 3.5 to 5 μm instead of 3 to 5 μm, and the wavelength range is set to 8 to 11 μm instead of 8 to 12 μm in consideration of the film configuration. This is because it is optically impossible to simultaneously satisfy both the bands of transmission in the wavelength range of 3 to 5 μm and reflection of 8 to 12 μm. Therefore, the band to be separated becomes narrower than the former, but it is sufficiently effective for the purpose of the present invention.

It should be further emphasized that the filter of the prior art cannot be directly applied to the purpose of the present invention. Among the filters of the prior art, for example, in the long wavelength transmission filter, an important problem is that the desired pass band is It is to cut the short wavelength side as sharply as possible. Therefore, design such that a high reflection band that blocks the transmission of light and a transmission band that transmits the light appear exactly next to each other, or provide a stop band by absorption at a place apart from the transmission band. There is. That is, the long-wavelength transmission filter is designed to have a high transmittance with respect to a desired wavelength, but the reflectance is generally not considered.

[0007]

The infrared optical multilayer film of the present invention is an infrared optical film formed on a substrate made of ZnS, in which 17 or more layers of Ge and ZnS are alternately formed in order from the substrate. layers below stacking an odd number of times, Y ₂ O ₃ as an outermost layer _{thereon, Sc 2 O 3, HfO 2} , TiO 2 or ZrO
By laminating a metal oxide selected from ₂ , infrared rays within a wavelength range of 3 to 5 μm are reflected and a wavelength of 8
It is characterized by transmitting infrared rays in the range of ˜12 μm.

Another infrared optical multilayer film of the present invention is an infrared optical film formed on a substrate made of ZnS, wherein the first layer from the substrate is TiO ₂ or Zr.
O ₂ was laminated, and ZnS and Ge were alternately laminated thereon in an odd number of times of 7 or more and 51 or less, and further thereon, YF ₃ , CeF ₃ , CaF ₂ or cryolite (Na ₃ AlF ₆₎ as the outermost layer. By laminating a metal fluoride selected from (1), infrared rays in the wavelength range of 3.5 to 5 μm are transmitted and infrared rays in the wavelength range of 8 to 11 μm are reflected. .

In the infrared optical multilayer film that reflects infrared rays in the wavelength range of 3 to 5 μm and transmits infrared rays in the wavelength range of 8 to 12 μm, the optical film thickness of the first layer Ge from the substrate (= Refractive index x physical film thickness) is 0.56 μm,
The alternating layers of ZnS and Ge from the second layer are laminated 7 times or more and 35 layers or less an odd number of times, and their optical film thicknesses are all 1.13 μm.
m, the optical thickness of the Ge layer on it is 1.00 μm, and the alternating layers of ZnS and Ge from thereabove are laminated 7 times or more and 35 layers or less an odd number of times, and the optical thickness is 0.88 μm or more. It is preferable that the optical thickness of the Ge layer is 0.44 μm, and the optical thickness of the metal oxide on the Ge layer is 2.69 μm.

In addition, infrared rays in the wavelength range of 3.5-5 μm
Transmits and reflects infrared rays in the wavelength range 8-11 μm
In the infrared optical multilayer film, the first layer T from the substrate
iO ₂Or ZrO₂Optical thickness of 1.00 μm, second layer
The optical film thickness of the ZnS layer of the eye is 1.15 μm, and from the third layer
Alternating layers of Ge and ZnS of 5 to 49 layers
And the optical film thickness is 2.30 μm, Z
The optical thickness of the nS layer is 1.15 μm, and the metal above
The optical thickness of the fluoride layer is preferably 0.59 μm.
Good

Although the optical film thickness is defined as described above, when determining the optical film thickness, it is necessary to determine which wavelength of the refractive index value is used. This is because the optical film thickness is defined by the product of the refractive index of the material and the physical film thickness, and therefore the dispersion of the refractive index of the material (the refractive index depends on the wavelength) must be considered. . Usually, the optical film thickness is determined based on the value of the "center wavelength" which is the center of the wavelength range to be used. Is 7.5 μm
It was decided based on the refractive index value of. However, since the allowable value of the film thickness relating to the present invention is quite large and an error of about ± 8% is recognized, even if the refractive index dispersion of the material is taken into consideration,
In practice, values for any wavelength in the wavelength range 3-12 μm may be used.

Further, the lower limit of the number of times of laminating the odd number of times is determined from the viewpoint of whether a predetermined effect can be obtained with respect to the reflectance or the transmittance in the desired wavelength range, while the upper limit of the number of times of the lamination is It is decided from the viewpoint of whether or not the predetermined effect can be obtained with respect to an increase in manufacturing cost. The reflectance or transmittance of the optical multilayer film obtained by the present invention is shown in FIGS. 33 to 47 showing the reflectance or transmittance measured for each optical multilayer film in Examples 24 to 38.

The infrared optical multilayer film of the present invention comprises Z
Using nS as a substrate, Ge and ZnS are alternately laminated from the substrate 17 times or more and 73 times or less in an odd number of times, and Y ₂ O ₃ , Sc ₂ O ₃ , HfO ₂ , TiO ₂ or ZrO is formed as the outermost layer thereon.
By laminating a metal oxide layer selected from ₂ ,
The optical multilayer film for infrared region has a characteristic of reflecting infrared rays having a wavelength range of 3 to 5 μm and transmitting infrared rays having a wavelength range of 8 to 12 μm.

The infrared optical multilayer film of the present invention is Z
Using nS as a substrate, TiO ₂ or ZrO ₂ is laminated as the first layer from the substrate, and ZnS and Ge are alternately laminated thereon in an odd number of times from 7 layers to 51 layers an odd number of times, and as the outermost layer further thereon. By laminating a metal fluoride selected from YF ₃ , CeF ₃ , CaF ₂ or cryolite (Na ₃ AlF ₆ ), infrared rays having a wavelength range of 3.5 to 5 μm are transmitted and a wavelength range of 8 to 11 μm is transmitted. It becomes an infrared multi-layer film having a characteristic of reflecting infrared rays.

Further, in the infrared multi-layer film for infrared region of the present invention which reflects infrared rays in the wavelength range of 3 to 5 μm and transmits infrared rays in the wavelength range of 8 to 12 μm, the first layer from the substrate is used.
The optical film thickness of Ge of the first layer is 0.56 μm, the alternating layers of ZnS and Ge from the second layer are laminated 7 times or more and 35 layers or less an odd number of times, and the optical film thicknesses thereof are all 1.13 μm. Ge
The optical thickness of the layer is 1.00 μm, ZnS and G
The alternating layers of e are laminated 7 times or more and 35 layers or less an odd number of times, the optical thicknesses of all are 0.88 μm, the optical thickness of the Ge layer thereon is 0.44 μm, and the optical thickness of the metal oxide layer is further thereon. If the film thickness is 2.69 μm, the wavelength range is 3 to 5 μm.
The reflection characteristics and the transmission characteristics in the wavelength range of 8 to 12 μm are excellent.

The wavelength range of the present invention is 3.5 to 5 μm.
In the infrared optical multi-layer film for transmitting infrared rays and reflecting infrared rays in the wavelength range of 8 to 11 μm, the first layer of TiO ₂ or ZrO _{2 from} the substrate has an optical film thickness of 1.00.
μm, the optical thickness of the second ZnS layer is 1.15 μm,
The alternating layers of Ge and ZnS from the third layer are laminated 5 times or more and 49 layers or less an odd number of times, and their optical film thicknesses are all 2.30 μm.
m, the optical film thickness of the ZnS layer thereon is 1.15 μm, and the optical film thickness of the metal fluoride layer thereon is 0.59 μm, the transmission characteristics and the wavelength range of 3.5 to 5 μm are obtained. The reflection property of 8 to 11 μm becomes good.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The optical film and optical element for infrared region of the present invention will be described in detail below with reference to the accompanying drawings.

1 to 4 are cross-sectional explanatory views showing the structure of an embodiment of an infrared antireflection film of the present invention. 5 and 6 are cross-sectional explanatory views showing the structure of an embodiment of the optical film for a beam splitter of the present invention. 7 and 8 show
It is explanatory drawing of the beam splitter of this invention. FIG. 9 is a cross-sectional explanatory view of an example of a vapor deposition apparatus used for manufacturing the infrared optical film of the present invention. 10 to 32 are graphs showing the infrared spectral transmittances of the Ge substrate and the ZnS substrate having the infrared antireflection film obtained in each of Examples 1 to 23 of the present invention. 33 to 47,
It is a figure which shows the infrared spectral transmittance of the ZnS board | substrate which has the optical film for beam splitters obtained in each of Example 24 thru | or 38 of this invention. 48 to 49 are
Incidence angle of 45 ° of the beam splitter using ZnS as a substrate obtained in each of Examples 39 to 40 of the present invention
It is a figure which shows the infrared spectral reflectance and spectral transmittance of.

First, as shown in FIG. 1, the infrared antireflection film of the present invention has a ZnS layer 2, a Si or Ge layer 3 in that order with a Ge lens or window as a substrate 1.
It is characterized in that the ZnS layer 2, the metal oxide layer 4, and the metal fluoride layer 5 are arranged. In addition, the infrared region in the present invention means a range of wavelength 3 to 12 μm, and depending on the case, it is divided into two ranges of wavelength 3 to 5 μm and wavelength 8 to 12 μm which are windows of the atmosphere.

Further, as shown in FIG. 2, another infrared reflection preventing film of the present invention uses a ZnS lens or window as a substrate 6 in order of Si or Ge layer 3 and Zn.
It is characterized in that the S layer 2, the Si or Ge layer 3, the ZnS layer 2, the metal oxide layer 4, and the metal fluoride layer 5 are arranged.

As shown in FIG. 3, another anti-reflection coating for the infrared region of the present invention uses a Si lens 7, a ZnS layer 2, a metal oxide in this order with a Ge lens or window as the substrate 1. It is characterized in that the layer 4 and the metal fluoride layer 5 are arranged.

As shown in FIG. 4, another infrared antireflection film of the present invention has a ZnSe lens 8 and a ZnS or TiO ₂ layer 9 in this order with a ZnS lens or window as the substrate 6. It is characterized in that the Y ₂ O ₃ or Sc ₂ O ₃ layer 10 and the metal fluoride layer 5 are arranged.

The method of arranging these materials is as a result of the inventors' earnestly researching from various combinations by repeating calculation and trial production of an optical multilayer film by a computer so as to meet the purpose of the present invention. It was chosen.

As the metal oxide layer, for example, Al
₂O₃, Sb₂O₃, HfO₂, In₂O ₃, Nd₂O₃, Sc₂
O₃, SiO, Ta₂O₃, TiO₂, Y₂O₃, ZrO₂,
ThO₂Oxides such as
Material that is transparent to light with a wavelength of 3 to 12 μm
Y because it has no refractive index and no toxicity₂O₃, Sc₂O₃,
HfO₂, TiO₂, ZrO₂It is one kind selected from
And are preferred.

Examples of the above metal fluorides include metal fluorides such as MgF ₂ , CeF ₃ , YF ₃ , CaF ₂ , cryolite, AlF ₃ , LiF ₂ , BaF ₂ and ThF _4. , Wavelength of which is 3 ~ 12μm
Is transparent to the light, the refractive index and toxicity of the material, and the durability as the outermost layer of the multilayer film, Y
It is preferably one selected from F ₃ , CeF ₃ , CaF _{2 and} cryolite.

On the other hand, the optical multilayer film for a beam splitter of the present invention, as shown in FIG. 5, has a Ge layer 11 and a ZnS layer 2 alternately formed on a ZnS substrate 6 in the order of 17 from the substrate.
It is characterized in that the metal oxide layer 4 is laminated an odd number of times over the number of layers and less than 73 layers, and the metal oxide layer 4 is further laminated thereon.

The Ge layer and the ZnS layer may be laminated in any structure as long as the thickness and the number of layers are selected so as to reflect infrared rays in the wavelength range of 3 to 5 μm. The film thickness and the number of layers can be determined by repeating the characteristic prediction by the calculation of the film and the trial manufacture.

The metal oxide layer is made of Ge and ZnS.
The alternating layers reduce the ripple in the transmission band outside the reflection band. Examples of such a metal oxide layer include Al ₂ O ₃ , Sb ₂ O ₃ , HfO ₂ , and In.
₂ O ₃ , Nd ₂ O ₃ , Sc ₂ O ₃ , SiO, Ta ₂ O ₃ , TiO
_{2, Y 2 O 3, ZrO} 2, may be mentioned oxides such as ThO _2, and it is transparent in the wavelength range 3 to 12 [mu] m,
Due to the refractive index of the material and the lack of toxicity, Y ₂ O ₃ , Sc ₂
1 selected from O ₃ , HfO ₂ , TiO ₂ , and ZrO ₂
It is preferably a seed.

The infrared optical multilayer film of the present invention has good reflection characteristics in a wavelength range of 3 to 5 μm and a wavelength range of 8 to 1
If you want to give good transmission characteristics at 2 μm,
The optical thickness of Ge of the layer is 0.56 μm, the alternating layers of ZnS and Ge from the second layer are laminated at least 7 layers and 35 layers or less an odd number of times, and the optical thickness of all of them is 1.13 μm. The optical thickness of the Ge layer is 1.00 μm, and alternating layers of ZnS and Ge are laminated at least 7 layers and 35 layers or less an odd number of times, and the optical thickness is 0.88 μm. It is preferable that the optical film thickness is 0.44 μm, and the optical film thickness of the metal oxide layer thereon is 2.69 μm.

It is desirable for these optical film thicknesses to be as close as possible to the above-mentioned numerical values from the viewpoint of characteristics, but sufficient characteristics can be obtained even if an error of about ± 8% occurs during manufacture.

Further, as shown in FIG. 6, another infrared optical multilayer film of the present invention has a TiO ₂ layer or a ZrO ₂ layer 12 as the first layer on the substrate 6 made of ZnS. Is laminated, and a ZnS layer and a Ge layer are alternately laminated thereon in an odd number of times of 7 or more and 51 or less, and a metal fluoride layer is further laminated thereon.

The ZnS layer and the Ge layer may be laminated in any structure as long as the film thickness and the number of layers are selected so as to reflect infrared rays in the wavelength range of 8 to 11 μm. The film thickness and the number of layers can be determined by repeating the prediction of the characteristics by the calculation of the optical multilayer film and the trial manufacture.

However, here, alternating layers of ZnS and Ge are
If infrared rays within a wavelength range of 8 to 12 μm, which is a wider band, are selected to be reflected, a high reflection band having a high light reflectance occurs even within a wavelength range of 3 to 4 μm, and high transmission is achieved in this wavelength band. The rate cannot be expected. Wavelength range 8-11
When limited to the μm band, the high reflection band remains below 3.5 μm, which is not perfect for the purposes of the present invention, but is well matched.

Also, the first layer of TiO₂Or ZrO₂Layers and
The outermost metal fluoride layer is an alternating layer of Ge and ZnS.
It also reduces the ripple in the transmission band outside the high reflection band.
Of. TiO as first layer₂Or ZrO₂Was chosen
Has a preferable refractive index for reducing ripple.
This is because Also, as the outermost metal fluoride layer
For MgF₂, CeF₃, YF₃, CaF₂, Cryola
Ito, AlF₃, LiF ₂, BaF₂Or ThF_FourSuch as
Metal fluorides can be mentioned, but in the wavelength range of 3 to 12 μm
Transparency, refractive index and toxicity of materials,
Considering the durability as the outermost layer, YF₃, CeF₃,
CaF₂Or one selected from cryolite
Is preferred.

The infrared optical multilayer film of the present invention has good transmission characteristics in the wavelength range of 3.5 to 5 μm and a wavelength of 8 μm.
In order to give good reflection characteristics within the range of ˜11 μm, the optical thickness of TiO ₂ or ZrO ₂ of the first layer is 1.00 μm, the ZnS layer of the second layer is 1.15 μm, Alternating layers of Ge and ZnS layers from the third layer are laminated 5 times or more and 49 layers or less an odd number of times, and the optical film thicknesses thereof are all 2.30 μm.
The ZnS layer preferably has an optical film thickness of 1.15 μm, and the metal fluoride layer thereon has an optical film thickness of 0.59 μm.

It is desirable in terms of characteristics that these optical film thicknesses are as close as possible to the above-mentioned numerical values, but sufficient characteristics can be obtained even if an error of about ± 8% occurs during manufacture.

Next, the infrared beam splitter of the present invention will be described.

The infrared beam splitter of the present invention uses ZnS, which is a parallel plate, as a substrate and has a wavelength of 3
Reflects infrared rays in the range of ˜5 μm and has a wavelength of 8 to 12
Coated with a multilayer film that transmits infrared rays within the range of μm, and the other surface has a wavelength within the range of 3 to 5 μm and 8 to 12 μm.
It is characterized by coating a multilayer film having an antireflection property in both bands within the range.

FIG. 7 shows an example of how to use this beam splitter. A multilayer film 14 that reflects infrared rays in the wavelength range of 3 to 5 μm and transmits infrared rays in the wavelength range of 8 to 12 μm on the infrared ray incident surface side of the ZnS substrate 13 and wavelengths of 3 to 5 μm in the emission surface side. Within 5 μm and 8
The multilayer film 15 having the antireflection property is arranged in both bands within the range of ˜12 μm. Therefore, of the incident infrared rays 16, infrared rays 17 in the wavelength range of 3 to 5 μm
Is reflected and infrared rays 18 in the wavelength range of 8 to 12 μm are transmitted, whereby these two wavelength bands are separated. Moreover, since the antireflection film on the emission surface side has antireflection characteristics in both the wavelength range of 3 to 5 μm and the wavelength range of 8 to 12 μm, the infrared ray reflection 19 on the emission surface side is small ( That is, it is possible to obtain good characteristics as a beam splitter in which the reflection between the front and back surfaces of the substrate is small (multiple reflection is small).

Another beam splitter for the infrared region of the present invention uses ZnS, which is a parallel plate, as a substrate and transmits infrared rays in the wavelength range of 3.5 to 5 μm to one surface of the substrate and has a wavelength of 8 to 11 μm. Is coated with a multi-layered film that transmits infrared rays within the range, and the other surface is coated with a multi-layered film having antireflection properties in both the wavelength range of 3 to 5 μm and the wavelength range of 8 to 11 μm. It is what

FIG. 8 shows an example of how to use this beam splitter. Infrared rays in the wavelength range of 3.5 to 5 μm are transmitted to the infrared ray incident surface side of the ZnS substrate 13.
In addition, the multilayer film 20 that reflects infrared rays in the wavelength range of 8 to 11 μm, and the multilayer film having the antireflection property in both the wavelength range of 3 to 5 μm and the wavelength range of 8 to 12 μm on the emitting surface side. 21 is arranged. Therefore, of the incident infrared rays 16, the infrared rays 22 within the wavelength range of 8 to 11 μm are reflected, and the infrared rays 23 within the wavelength range of 3.5 to 5 μm.
Are transmitted, the two wavelength bands are separated. Moreover, since the antireflection film on the emission surface side has antireflection characteristics in both the wavelength bands of 3 to 5 μm and 8 to 12 μm, the reflection 24 of infrared rays on the emission surface side is small (that is, the multiple layers in the substrate). Good characteristics can be obtained as a beam splitter (with small reflection).

It is needless to say that the infrared optical film of the present invention described above can be applied to the optical film having these characteristics coated on the ZnS substrate.

The method for forming the optical film for the infrared region is not particularly limited, and examples thereof include a vacuum vapor deposition method, an ion plating method, a sputtering method and a CVD method. Among them, the vacuum vapor deposition method for forming an optical multilayer film is preferable from the viewpoint of film thickness control and film thickness uniformity. Hereinafter, the method and a vacuum vapor deposition apparatus for carrying out the method will be described.

FIG. 9 is a sectional view showing an example of the vapor deposition apparatus. In FIG. 9, 33 is a vacuum container for obtaining a high vacuum, and 25 is a substrate mounting dome for mounting a substrate 26 to be deposited, which is rotated during the deposition to improve the uniformity of the film. 27 is a crucible for containing the vapor deposition material,
After placing the necessary materials and amounts in the crucible, they are placed on the crucible rotation stage 28. The crucible 27 is moved by the crucible rotating stage 28 to a position where the crucible containing the substance to be deposited hits the electron beam emitted from the electron gun 29. The substance heated and evaporated by the electron beam is deposited on the surface of the substrate 26 to form a film. The thickness of this vapor-deposited film is measured by measuring the film thickness of the monitor glass substrate 31 with a reflective optical film thickness meter 30 mounted above the vacuum container 33, and when the desired thickness is reached. The shutter 32 closes. In the same manner, the infrared optical film of the present invention can be obtained by sequentially forming vapor-deposited films of different layers with a predetermined thickness in the same manner.

The electron beam evaporation method in each of the examples described later was carried out by the above-mentioned method. However, the heating of the evaporation material is not limited to the electron beam method, but resistance heating in which a current is applied to a metal crucible to heat it. The method can also be used. Also, as the optical film thickness meter, not only a reflection type film thickness meter but also a transmission type film thickness meter in which a light source is provided below a vacuum container can be used.

Next, the infrared optical film and optical element of the present invention will be described in more detail with reference to specific examples.

[Examples 1 to 7] Diameter 30 mmφ, thickness 1
The Ge substrate with both sides of mm being polished is attached to the substrate mounting dome of the vapor deposition apparatus, and the degree of vacuum is 1 × 10 ⁻⁴ torr.
In the following, the materials shown in Table 1 and films having an optical film thickness were sequentially laminated from the substrate by an electron beam evaporation method to form an antireflection film for infrared region. As the refractive index value for determining the optical film thickness, a value near the infrared wavelength of 7.5 μm was used.

Ge on the opposite surface of the substrate was vapor-deposited by the same procedure to form an infrared antireflection film on both surfaces.
I got each substrate.

The transmittance of the obtained substrate was measured by a Fourier transform infrared spectrophotometer (JIR-7000 manufactured by JEOL Ltd.). The spectral transmittance curves are shown in FIGS.

[Embodiments 8 to 11] Ge substrates having a diameter of 30 mm and a thickness of 1 mm, both surfaces of which were polished, were formed into Ge substrates.
By the same method as described in (1), the materials shown in Table 2 and films having an optical film thickness were laminated on both sides of the substrate to form an infrared antireflection film. The transmittance of the obtained substrate was measured by the same method as in Examples 1-7. The spectral transmittance curve is shown in FIG.
Shown in 20.

[Examples 12 to 19] A ZnS substrate having a diameter of 30 mm and a thickness of 1 mm and having both sides polished was prepared as in Example 1.
In the same manner as in Nos. 7 to 7, the materials shown in Table 3 and films having optical thicknesses were laminated on both surfaces of the substrate to form an infrared antireflection film. The transmittance of the obtained substrate was measured by the same method as in Examples 1-7. Figure 2 shows the spectral transmittance curve.
1 to 28.

[Examples 20 to 23] A ZnS substrate having a diameter of 30 mm and a thickness of 1 mm and having both sides polished was prepared as in Example 1.
In the same manner as in Nos. 7 to 7, the materials shown in Table 4 and films having optical thicknesses were laminated on both surfaces of the substrate to form an infrared antireflection film. The transmittance of the obtained substrate was measured by the same method as in Examples 1-7. The spectral transmittance curve is shown in FIG.
~ 32.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4]

From the transmittance measurement results shown in FIGS. 10 to 32, it can be seen that in the case of the examples of the present invention, a high transmittance was obtained in the desired transmission band.

[Examples 24 to 30] A ZnS substrate having a diameter of 50 mmφ and a thickness of 1 mm and having both sides polished was attached to a substrate mounting dome of a vapor deposition apparatus, and the degree of vacuum was 1 × 10 ⁻⁴ t.
An optical film for a beam splitter was formed on one surface of the substrate by stacking materials having the optical thicknesses shown in Tables 5 to 7 in order from the substrate by an electron beam evaporation method at or or less.

The spectral transmittance and spectral reflectance of the obtained substrate were measured by Fourier transform infrared spectrophotometer (J
IR-7000) and a reflection measurement holder (IR-RSC100 manufactured by JEOL Ltd.). The spectral transmittance curve and the spectral reflectance curve are shown in FIGS.

[Examples 31 to 37] A ZnS substrate having a diameter of 50 mm and a thickness of 1 mm and having both sides polished was prepared as in Example 2.
In the same manner as in 4 to 30, the materials shown in Tables 8 to 11 and films having optical thicknesses were laminated to form an optical film for a beam splitter. The spectral transmittance and spectral reflectance of the obtained substrate were measured by the same method as in Examples 24-30. The spectral transmittance curve and the spectral reflectance curve are shown in FIG.
~ 47.

[0061]

[Table 5]

[0062]

[Table 6]

[0063]

[Table 7]

[0064]

[Table 8]

[0065]

[Table 9]

[0066]

[Table 10]

[0067]

[Table 11]

From the measurement results of the transmittance and the reflectance shown in FIGS. 33 to 39, in the case of the embodiment of the present invention, the wavelength is 3 to 5 μm.
Has a high reflectance within the range of m and has a wavelength of 8 to 12 μm.
It can be seen that an optical film for a beam splitter having a high transmittance within the range of m is obtained.

From the measurement results of the transmittance and the reflectance shown in FIGS. 40 to 47, in the case of the embodiment of the present invention, the transmittance is high in the wavelength range of 3.5 to 5 μm, and It can be seen that an optical film for a beam splitter having a high reflectance in the wavelength range of 8 to 11 μm is obtained.

[Example 39] Diameter 50 mmφ, thickness 1 m
For a substrate made of ZnS whose both sides of m were polished, an antireflection film according to Example 12 was formed on one side of the substrate, and an optical film according to Example 24 was formed on the other side, and the wavelength was 3 to 5 μm.
A beam splitter for separating two wavelength bands by reflecting infrared rays within the range of 8 and transmitting infrared rays within the range of wavelength 8 to 12 μm was manufactured.

Incident angle of the produced beam splitter is 45 °
Were measured with a Fourier transform infrared spectrophotometer (JIR-7000 manufactured by JEOL Ltd.) and an angle variable reflection measurement holder (IR-RSC110). The incident angle is set to 45 ° because infrared rays are tried to be separated by changing the direction of reflected light by 90 ° with respect to transmitted light. The measurement result is shown in FIG.

[Embodiment 40] Diameter 50 mmφ, thickness 1 m
For a ZnS substrate whose both sides of m were polished, an antireflection film according to Example 13 was formed on one side of the substrate, and an optical film according to Example 31 was formed on the other side of the substrate. 5
Infrared rays in the range of μm are transmitted, and the wavelength is 8 to 11 μm.
A beam splitter that separates two wavelength bands by reflecting infrared rays within the range of m was manufactured.

The transmittance and reflectance of the produced beam splitter at an incident angle of 45 degrees were measured by the same method as in Example 39. The measurement result is shown in FIG.

From the transmittance and reflectance measurement results shown in FIG. 48, in the case of the example of the present invention, the incident infrared ray having an incident angle of 45 ° was reflected in the wavelength range of 3 to 5 μm, and the wavelength was 8 to 12 μm.
It can be seen that a beam splitter that transmits the range of m and the reflected light has a 90 ° direction with respect to the transmitted light is obtained.

Further, from the measurement results of the transmittance and the reflectance shown in FIG. 49, in the case of the embodiment of the present invention, the incident angle is 45 °.
Of the incident infrared ray of 3.5 to 5 μm is transmitted, and the wavelength of 8 to 11 μm is reflected.
It can be seen that the beam splitter is oriented at 0 °.

[0076]

According to the optical multilayer film for infrared region of the present invention,
Using ZnS as a substrate, Ge and ZnS are alternately laminated from the substrate in an odd number of times from 17 layers to 73 layers an odd number of times, and a metal oxide layer is further laminated thereon to provide a wavelength range of 3 to 5
There is an effect that an optical multilayer film for infrared region having a characteristic of reflecting infrared rays of μm and transmitting infrared rays of a wavelength range of 8 to 12 μm can be obtained.

According to another infrared optical multilayer film of the present invention, ZnS is used as the substrate, and T is used as the first layer from the substrate.
io ₂ or ZrO ₂ is laminated, and ZnS and G
e is alternately laminated 7 times or more and 51 layers or less an odd number of times, and by further laminating a metal fluoride as the outermost layer thereon, infrared rays in the wavelength range of 3.5 to 5 μm are transmitted, and the wavelength range of 8 to 11 μm is transmitted. There is an effect that an infrared multi-layer film having a characteristic of reflecting infrared rays can be obtained.

In the infrared optical multilayer film of the present invention which reflects infrared rays in the wavelength range of 3 to 5 μm and transmits infrared rays in the wavelength range of 8 to 12 μm, the metal oxides are Y ₂ O ₃ and Sc. _If selected from one of ₂ O ₃ , HfO ₂ , TiO ₂ or ZrO ₂ , wavelength range 8-12 μm
There is an effect that a good infrared transmission property of can be obtained.

In the infrared optical multilayer film of the present invention which transmits infrared rays in the wavelength range of 3.5 to 5 μm and reflects infrared rays in the wavelength range of 8 to 11 μm, the metal fluoride is YF ₃ or CeF. ₃ , one of CaF ₂ or cryolite, wavelength range 3.5-5
This has the effect of obtaining a good transmission characteristic of infrared rays of μm.

In the infrared optical multilayer film of the present invention which reflects infrared rays in the wavelength range of 3 to 5 μm and transmits infrared rays in the wavelength range of 8 to 12 μm, the first layer of Ge optical from the substrate is used. The film thickness is 0.56 μm, Z from the second layer
The alternating layers of nS and Ge are laminated 7 times or more and 35 layers or less an odd number of times, and the optical film thicknesses thereof are all 1.13 μm, and the Ge layer on top
The optical thickness of the layer is 1.00 μm, ZnS and G
The alternating layers of e are laminated 7 times or more and 35 layers or less an odd number of times, all of the optical films are 0.88 μm, the optical film of the Ge layer is 0.44 μm, and the optical film of the metal oxide layer is further thereon. If the thickness is 2.69 μm, the wavelength range is 3.5 to 5 μm.
There is an effect that good reflection characteristics of m and transmission characteristics of wavelength range 8 to 12 μm can be obtained.

The infrared wavelength range of the present invention is from 3.5 to
Transmits infrared rays of 5 μm and has a wavelength range of 8 to 11 μm
In the infrared optical multilayer film reflecting infrared rays, the optical thickness of the first layer of TiO ₂ or ZrO ₂ from the substrate is 1.00 μm, and the optical thickness of the second ZnS layer is 1.1.
The alternating layers of Ge and ZnS from the third layer of 5 μm are laminated 5 times or more and 49 layers or less an odd number of times, and their optical film thicknesses are all 2.3.
0 μm, the optical thickness of the ZnS layer thereon is 1.15 μm,
Further, the optical film thickness of the metal fluoride layer thereon is 0.59μ.
When m is set, there is an effect that excellent transmission characteristics in the wavelength range of 3.5 to 5 μm and reflection characteristics in the wavelength range of 8 to 11 μm can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing a structure of an embodiment of an infrared antireflection film of the present invention.

FIG. 2 is a cross-sectional explanatory view showing the structure of another embodiment of the infrared antireflection film of the present invention.

FIG. 3 is a cross-sectional explanatory view showing the structure of another embodiment of the infrared antireflection film of the present invention.

FIG. 4 is an explanatory cross-sectional view showing the structure of another embodiment of the infrared antireflection film of the present invention.

FIG. 5 is a cross-sectional explanatory view showing the structure of an example of the optical film for a beam splitter of the present invention.

FIG. 6 is a sectional explanatory view showing the structure of another embodiment of the optical film for a beam splitter of the present invention.

FIG. 7 is a diagram illustrating a beam splitter of the present invention.

FIG. 8 is a diagram illustrating another beam splitter of the present invention.

FIG. 9 is a cross-sectional explanatory view of an example of a vapor deposition apparatus used for manufacturing the infrared optical film of the present invention.

FIG. 10 is a diagram showing infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 1 of the present invention.

FIG. 11 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 2 of the present invention.

FIG. 12 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 3 of the present invention.

FIG. 13 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 4 of the present invention.

FIG. 14 is a diagram showing infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 5 of the present invention.

FIG. 15 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 6 of the present invention.

FIG. 16 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 7 of the present invention.

FIG. 17 is a diagram showing infrared spectral transmittance of a Ge substrate having an antireflection film for infrared region obtained in Example 8 of the present invention.

FIG. 18 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 9 of the present invention.

FIG. 19 is a diagram showing an infrared spectral transmittance of a Ge substrate having an infrared antireflection film obtained in Example 10 of the present invention.

FIG. 20 is a diagram showing infrared spectral transmittance of a Ge substrate having an antireflection film for infrared region obtained in Example 11 of the present invention.

FIG. 21 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 12 of the present invention.

FIG. 22 is a diagram showing infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 13 of the present invention.

FIG. 23 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 14 of the present invention.

FIG. 24 is a diagram showing infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 15 of the present invention.

FIG. 25 is a diagram showing infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 16 of the present invention.

FIG. 26 is a diagram showing infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 17 of the present invention.

FIG. 27 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 18 of the present invention.

FIG. 28 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 19 of the present invention.

FIG. 29 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 20 of the present invention.

FIG. 30 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 21 of the present invention.

FIG. 31 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 22 of the present invention.

FIG. 32 is a diagram showing an infrared spectral transmittance of a ZnS substrate having an infrared antireflection film obtained in Example 23 of the present invention.

FIG. 33 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 24 of the present invention.

FIG. 34 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having an optical film for a beam splitter obtained in Example 25 of the present invention.

FIG. 35 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having the beam splitter optical film obtained in Example 26 of the present invention.

FIG. 36 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having an optical film for a beam splitter obtained in Example 27 of the present invention.

FIG. 37 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 28 of the present invention.

FIG. 38 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having the beam splitter optical film obtained in Example 29 of the present invention.

FIG. 39 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 30 of the present invention.

FIG. 40 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 31 of the present invention.

FIG. 41 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 32 of the present invention.

FIG. 42 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having an optical film for a beam splitter obtained in Example 33 of the present invention.

FIG. 43 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having an optical film for a beam splitter obtained in Example 34 of the present invention.

FIG. 44 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 35 of the present invention.

FIG. 45 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 36 of the present invention.

FIG. 46 is a diagram showing infrared spectral reflectance and spectral transmittance of a ZnS substrate having an optical film for a beam splitter obtained in Example 37 of the present invention.

FIG. 47 is a diagram showing an infrared spectral reflectance and a spectral transmittance of a ZnS substrate having a beam splitter optical film obtained in Example 38 of the present invention.

FIG. 48 is a diagram showing infrared spectral reflectance and spectral transmittance at an incident angle of 45 ° of a beam splitter using ZnS as a substrate obtained in Example 39 of the present invention.

FIG. 49 is a diagram showing infrared spectral reflectance and spectral transmittance at an incident angle of 45 ° of a beam splitter using ZnS as a substrate obtained in Example 40 of the present invention.

[Explanation of symbols]

1 Ge substrate, 2 ZnS layer, 3 Si or Ge layer,
4 metal oxide layer, 5 metal fluoride layer, 6 ZnS substrate, 7 Si layer, 8 ZnSe layer, 9 ZnS or T
iO ₂ layer, 10 Y ₂ O ₃ or Sc ₂ O ₃ layer, 11 Ge
Layer, 12 TiO ₂ or ZrO ₂ layer, 13 ZnS substrate, 14 3-5 μm reflective and 8-12 μm transmissive optical film, 15 3-5 μm and 8-12 μm anti-reflective film, 16 incident infrared light, 17 incident surface of substrate 3 to 5 μm infrared light reflected at 18; 8 to 12 μm infrared light transmitted at 18; 19 infrared light reflected at the exit surface of the substrate;
Optical film having transmission of 5 to 5 μm and reflection of 8 to 11 μm, 21
Antireflection film of 3.5 to 5 μm and 8 to 11 μm, 2
2 Infrared rays of 8 to 11 μm reflected by the incident surface of the substrate, 2
3 Transmitted 3.5 to 5 μm infrared rays, 24 Infrared rays reflected from the exit surface of the substrate, 25 Substrate mounting dome, 26
Substrate, 27 crucible, 28 rotary stage, 29 electron gun, 30 reflective optical film thickness meter, 31 monitor glass substrate, 32 shutter, 33 vacuum container.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H048 FA05 FA12 FA16 FA24 GA04                       GA09 GA12 GA33 GA43                 2K009 AA02 BB01 CC03 CC06 CC14

Claims (4)

[Claims] 1. An infrared optical film formed on a substrate made of ZnS, wherein Ge and ZnS are alternately laminated 17 times or more and 73 times or less in an odd number in order from the substrate, and Y ₂ as an outermost layer is formed thereon. By laminating a metal oxide layer selected from O ₃ , Sc ₂ O ₃ , HfO ₂ , TiO ₂ or ZrO ₂ , infrared rays in the wavelength range of 3 to 5 μm are reflected, and in the wavelength range of 8 to 12 μm. An optical multi-layer film for infrared region, which is characterized by transmitting infrared rays. 2. In an infrared optical film formed on a substrate made of ZnS, TiO is used as a first layer from the substrate.
₂ or ZrO ₂ is laminated, and ZnS and Ge are alternately laminated thereon in an odd number of times of 7 or more and 51 or less, and YF ₃ , CeF ₃ , CaF ₂ or cryolite (Na _{3) is} further laminated thereon as an outermost layer. By laminating a metal fluoride selected from AlF ₆ ), infrared rays in the wavelength range of 3.5 to 5 μm are transmitted and infrared rays in the wavelength range of 8 to 11 μm are reflected. Optical multilayer film for use. 3. The optical thickness of Ge of the first layer from the substrate is 0.56 μm, and the alternating layers of ZnS and Ge from the second layer are laminated 7 times to 35 layers an odd number of times. The film thicknesses are all 1.13 μm, and the optical film thickness of the Ge layer thereon is 1.
Alternating layers of ZnS and Ge from the upper layer of 0.
88 μm, the optical thickness of the Ge layer thereon is 0.44 μm,
Further, the optical film thickness of the metal oxide layer thereon is 2.69 μm.
The optical multilayer film for infrared region according to claim 1. 4. An optical film thickness of TiO ₂ or ZrO ₂ of the first layer from the substrate is 1.00 μm, and Zn of the second layer is Zn.
The optical thickness of the S layer is 1.15 μm, the alternating layers of Ge and ZnS from the third layer are laminated 5 times or more and 49 layers or less an odd number of times, and the optical thicknesses of all are 2.30 μm, and the ZnS layer thereabove. The optical multilayer film for infrared region according to claim 2, wherein the optical film thickness is 1.15 μm, and the optical film thickness of the metal fluoride layer thereon is 0.59 μm.