Film-coated substrate and method for manufacturing the same

Abstract

To provide a substrate with a film capable of effectively increasing infrared transmittance when used for an infrared transmission lens.SOLUTION: There is provided a substrate with a film 1 in which a multilayer film 3 is placed on a substrate 2. The multilayer film 3 comprises: a first layer 4 which is an adhesion layer, placed on a principal plane 2a of the substrate 2; a second layer 5 placed on the first layer 4 and having a low refractive index film 7 with a relatively low refractive index and a high refractive index film 8 with a relatively high refractive index; and a third layer 6 which is the outer most layer, placed on the second layer 5. The low refractive index film 7 is composed of at least one of YF3 and YbF3 and the high refractive index film 8 is composed of Ge.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film-coated substrate having a multilayer film provided on the substrate, and a method for manufacturing the film-coated substrate. [Background technology]

[0002] In recent years, optical devices utilizing infrared light have become widely used. For example, in-vehicle night vision and security systems are equipped with infrared sensors used for detecting living organisms at night. Since infrared sensors detect infrared light with wavelengths of approximately 8 μm to 14 μm emitted from living organisms, optical components such as lenses or filters that transmit infrared light in this wavelength range are provided in front of the sensor.

[0003] As an example of such an optical component, Patent Document 1 discloses an optical component consisting of a substrate and an infrared anti-reflective coating. In Patent Document 1, the substrate is made of ZnSe. The infrared anti-reflective coating is composed of a low refractive index layer mainly made of BaF2, a high refractive index layer made of ZnSe, ZnS, or Ge, and an intermediate layer made of an amorphous or anisotropic material. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2012 / 049888 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, when ZnS is used as the material for the anti-reflective coating, as in Patent Document 1, a sulfurous odor is generated during film formation, requiring specialized equipment such as local exhaust ventilation systems, which leads to a decrease in productivity. Furthermore, when an anti-reflective coating like the one in Patent Document 1 is used in an infrared-transmitting lens, it is difficult to sufficiently increase the infrared transmittance.

[0006] The object of the present invention is to provide a film-coated substrate and a method for manufacturing the film-coated substrate that can effectively increase infrared transmittance when used in an infrared-transmitting lens. [Means for solving the problem]

[0007] The film-coated substrate according to the present invention is a film-coated substrate having a multilayer film provided on the substrate, wherein the multilayer film comprises a first layer provided on the main surface of the substrate and being an adhesion layer; a second layer provided on the first layer and having a low refractive index film with a relatively low refractive index and a high refractive index film with a relatively high refractive index; and a third layer provided on the second layer and being the outermost layer, wherein the low refractive index film is composed of at least one of YF3 and YbF3, and the high refractive index film is composed of Ge.

[0008] In the present invention, it is preferable that the first layer is composed of at least one of Y2O3 and Si.

[0009] In the present invention, it is preferable that the third layer is composed of at least one of Y2O3 and Si.

[0010] In the present invention, it is preferable that the ratio of the total thickness of the low refractive index film to the total thickness of the high refractive index film (low refractive index film / high refractive index film) in the second layer is 2.2 or more and 15 or less.

[0011] In the present invention, it is preferable that the low refractive index film and the high refractive index film are alternately laminated in the second layer.

[0012] In the present invention, it is preferable that the low refractive index film is composed of YF3.

[0013] In the present invention, it is preferable that the substrate is made of chalcogenide glass.

[0014] In the present invention, it is preferable that the multilayer film is an antireflection film.

[0015] In the present invention, it is preferable that the substrate with a film is used for an infrared transmission lens.

[0016] The method for manufacturing a substrate with a film according to the present invention is a method for manufacturing a substrate with a film configured according to the present invention, including a step of forming the first layer on the main surface of the substrate by a vacuum evaporation method or a sputtering method, a step of forming the second layer on the first layer by a vacuum evaporation method or a sputtering method, and a step of forming the third layer on the second layer by a vacuum evaporation method or a sputtering method.

[0017] In the present invention, in the step of forming the first layer, it is preferable to form the first layer so that the substrate side has a relatively sparse film structure and the second layer side has a relatively dense film structure.

[0018] In the present invention, in the step of forming the first layer, it is preferable to form the first layer by a vacuum evaporation method and irradiate ions by an ion assist method during the film formation.

[0019] In the present invention, in the step of forming the second layer, it is preferable to form the low refractive index film by a vacuum evaporation method under the condition that the film formation rate is 0.5 nm / sec or less.

[0020] In the present invention, in the step of forming the third layer, it is preferable to form the third layer so as to have a dense film structure.

[0021] In the present invention, in the step of forming the third layer, it is preferable to form the third layer by a vacuum evaporation method and irradiate ions by an ion assist method during the film formation.

Advantages of the Invention

[0022] According to the present invention, it is possible to provide a film-coated substrate and a method for manufacturing the film-coated substrate that can effectively increase the infrared transmittance when used in an infrared-transmitting lens. [Brief explanation of the drawing]

[0023] [Figure 1] Figure 1 is a schematic cross-sectional view showing a film-coated substrate according to one embodiment of the present invention. [Figure 2] Figure 2 shows the transmission spectrum of the film-coated substrate obtained in Example 1 at wavelengths from 3000 nm to 14000 nm. [Figure 3] Figure 3 shows the transmission spectra of the film-coated substrates obtained in Example 1 and Comparative Example 1 at wavelengths of 7000 nm to 14000 nm. [Figure 4] Figure 4 shows the reflectance spectrum of the film-coated substrate obtained in Example 12 at wavelengths of 6000 nm to 14000 nm. [Figure 5] Figure 5 shows the transmission spectrum of the film-coated substrate obtained in Example 13 at wavelengths of 4000 nm to 14000 nm. [Modes for carrying out the invention]

[0024] Preferred embodiments are described below. However, the following embodiments are merely illustrative, and the present invention is not limited to these embodiments. In addition, in each drawing, components having substantially the same function may be referred to by the same reference numerals.

[0025] [Membrane-coated substrate] (Anti-reflective film) Figure 1 is a schematic cross-sectional view showing a film-coated substrate according to one embodiment of the present invention. As shown in Figure 1, the film-coated substrate 1 comprises a substrate 2 and a multilayer film 3. In this embodiment, the multilayer film 3 is an anti-reflective film.

[0026] The base material 2 can be made of various materials depending on the required properties, but it is particularly preferable to have a high infrared transmittance when used in an infrared-transmitting lens. Specifically, the base material 2 preferably has an average infrared transmittance of 80% or more at wavelengths of 8 μm to 14 μm with a thickness of 2 mm, more preferably 85% or more, and even more preferably 90% or more.

[0027] The base material 2 is preferably composed of an infrared-transmitting glass having high infrared transmittance, Ge, ZnS, etc. Examples of infrared-transmitting glass that constitute the base material 2 include chalcogenide glass. In particular, from the viewpoint of further increasing infrared transmittance, it is preferable that the base material 2 is composed of chalcogenide glass.

[0028] Chalcogenide glass contains Te as an essential component. Te, a chalcogen element, forms the glass skeleton and enhances infrared transmittance. The Te content is preferably 20% to 99%, more preferably 40% to 95%, even more preferably 50% to 85%, particularly preferably 60% to 85%, and most preferably 70% to 80% in mole percent. If the Te content is too low, vitrification becomes difficult, and infrared transmittance tends to decrease. On the other hand, if the Te content is too high, the thermal stability of the glass tends to decrease, and Te-based crystals tend to precipitate. Other chalcogen elements, Se and S, do not improve infrared transmittance as much as Te, and the infrared transmission limit wavelength may be shorter.

[0029] In addition to the components listed above, chalcogenide glass may also contain the following components:

[0030] Ge is a component that expands the vitrification range and enhances the thermal stability of glass without reducing infrared transmittance. The Ge content is preferably 0% to 40%, more preferably 1% to 35%, even more preferably 5% to 30%, particularly preferably 7% to 25%, and most preferably 10% to 20% in mole percent. If the Ge content is too high, Ge-based crystals may easily precipitate, and raw material costs tend to increase.

[0031] Ga is a component that expands the vitrification range and enhances the thermal stability of glass without reducing infrared transmittance. The Ga content is preferably 0% to 30%, more preferably 1% to 30%, even more preferably 3% to 25%, particularly preferably 4% to 20%, and most preferably 5% to 15% in mole percent. If the Ga content is too high, Ga-based crystals may easily precipitate, and raw material costs tend to increase.

[0032] Ag is a component that broadens the vitrification range and improves the thermal stability of glass. The Ag content is preferably 0% to 20% in mole percent, more preferably 1% to 10%. If the Ag content is too high, vitrification may become difficult.

[0033] Al is a component that broadens the vitrification range and improves the thermal stability of the glass. The Al content is preferably 0% to 20%, more preferably 0% to 10%, in molar percent. If the Al content is too high, vitrification may become difficult.

[0034] Sn is a component that broadens the vitrification range and improves the thermal stability of the glass. The Sn content is preferably 0% to 20%, more preferably 0% to 10%, in mole percent. If the Sn content is too high, vitrification may become difficult.

[0035] The shape of the substrate 2 is not particularly limited and may include, for example, a disc shape, a rectangular plate shape, a lens shape, a prism shape, etc.

[0036] The thickness of the substrate 2 is not particularly limited and can be set appropriately according to the infrared transmittance, etc. The thickness of the substrate 2 can be, for example, about 0.5 mm to 3 mm.

[0037] As shown in Figure 1, the substrate 2 has opposing first main surface 2a and second main surface 2b. A multilayer film 3 is provided on the first main surface 2a of the substrate 2. In this embodiment, the multilayer film 3 is provided only on the first main surface 2a on one side of the substrate 2, but the multilayer film 3 may be provided on both the first main surface 2a and the second main surface 2b on both sides of the substrate 2.

[0038] The multilayer film 3 has a first layer 4, a second layer 5, and a third layer 6. More specifically, the first layer 4, which is an adhesion layer, is provided on the first main surface 2a of the substrate 2. The second layer 5 is provided on the first layer 4. The third layer 6, which is the outermost layer, is provided on the second layer 5.

[0039] In this embodiment, the first layer 4 is composed of at least one of Y2O3 and Si, and is a film mainly composed of at least one of Y2O3 and Si. Therefore, the first layer 4 may be composed of Y2O3 only, or of Si only, or of both Y2O3 and Si. When the first layer 4 is composed of such materials, the infrared transmittance of the film-coated substrate 1 can be further increased. Furthermore, the adhesion between the first layer 4 and the substrate 2 such as chalcogenide glass, and the adhesion between the first layer 4 and the second layer 5 can be further increased. If there is no problem with adhesion, the first layer 4 may be a film mainly composed of Ge, YF3, YbF3, etc. These materials for the first layer 4 may be used individually, or multiple types may be used in combination.

[0040] In this specification, the term "main component membrane" refers to a membrane in which the material makes up 50% or more of the membrane. Naturally, a membrane containing 100% of the material is also acceptable. The same applies hereafter.

[0041] The thickness of the first layer 4 is not particularly limited, but is preferably 10 nm or more, more preferably 30 nm or more, more preferably 100 nm or less, and more preferably 60 nm or less.

[0042] The second layer 5 is a multilayer film having a low refractive index film 7 with a relatively low refractive index and a high refractive index film 8 with a relatively high refractive index. In this embodiment, the second layer 5 is constructed by alternately stacking the low refractive index film 7 and the high refractive index film 8 in that order on the first layer 4.

[0043] In this embodiment, the low refractive index film 7 is composed of at least one of YF3 and YbF3, and is a film mainly composed of at least one of YF3 and YbF3. Therefore, the low refractive index film 7 may be composed of YF3 only, or YbF3 only, or both YF3 and YbF3. When the low refractive index film 7 is composed of such materials, the infrared transmittance of the film-coated substrate 1 can be further increased. From the viewpoint of further increasing the infrared transmittance of the film-coated substrate 1, it is preferable that the low refractive index film 7 is composed of YF3.

[0044] The film thickness per layer of the low refractive index film 7 is not particularly limited, but is preferably 50 nm or more, more preferably 100 nm or more, preferably 1600 nm or less, and more preferably 1300 nm or less.

[0045] Furthermore, the high refractive index film 8 is composed of Ge, and is a film with Ge as its main component. When the high refractive index film 8 is composed of such a material, the infrared transmittance of the film-coated substrate 1 can be further increased.

[0046] The film thickness per layer of the high refractive index film 8 is not particularly limited, but is preferably 40 nm or more, more preferably 60 nm or more, preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, particularly preferably 100 nm or less, and most preferably 75 nm or less. By setting the film thickness within this range, absorption loss due to the Ge layer can be suppressed, and the decrease in infrared transmittance can be further suppressed. Furthermore, production costs can be further reduced.

[0047] Furthermore, the total thickness of the high refractive index film 8 is not particularly limited, but is preferably 100 nm or more, more preferably 150 nm or more, preferably 700 nm or less, more preferably 600 nm or less, even more preferably 500 nm or less, and particularly preferably 400 nm or less. By setting the total thickness within this range, absorption loss due to the Ge layer can be suppressed, and the decrease in infrared transmittance can be further suppressed. In addition, production costs can be further reduced.

[0048] The overall thickness of the second layer 5 is not particularly limited, but is preferably 1000 nm or more, more preferably 1700 nm or more, more preferably 3000 nm or less, and more preferably 2400 nm or less.

[0049] Furthermore, the total number of layers in the film constituting the second layer 5 is preferably 3 or more, more preferably 5 or more, preferably 10 or fewer, and more preferably 7 or fewer.

[0050] In this embodiment, the third layer 6 is composed of at least one of Y2O3 and Si, and is a film mainly composed of at least one of Y2O3 and Si. Therefore, the third layer 6 may be composed only of Y2O3, or only of Si, or both of Y2O3 and Si. When the third layer 6 is composed of such materials, the infrared transmittance of the film-coated substrate 1 can be further increased. Furthermore, the weather resistance of the film-coated substrate 1 can be further increased. However, the third layer 6 may also be a film mainly composed of Ge, YF3, YbF3, etc. The materials for the third layer 6 may be used individually or in combination of multiple types.

[0051] The thickness of the third layer 6 is not particularly limited, but is preferably 10 nm or more, more preferably 30 nm or more, more preferably 100 nm or less, and more preferably 60 nm or less.

[0052] Since the film-coated substrate 1 of this embodiment has the above configuration, it can effectively increase the infrared transmittance when used in an infrared-transmitting lens.

[0053] Conventionally, when ZnS was used as a material for anti-reflective coatings, a sulfurous odor was generated during film formation, requiring specialized equipment such as local exhaust ventilation systems, which led to a decrease in productivity. Furthermore, when such anti-reflective coatings were used in infrared-transmitting lenses, it was difficult to sufficiently increase the infrared transmittance.

[0054] In response to this, the present inventors focused on the film structure of the multilayer film 3 in a film-coated substrate 1 on which a multilayer film 3 is provided on a substrate 2, and found that the infrared transmittance can be effectively increased by having a second layer 5 which includes a low refractive index film 7 composed of YF3 and YbF3 and a high refractive index film 8 composed of Ge.

[0055] Thus, the film-coated substrate 1 of this embodiment can effectively increase infrared transmittance without using ZnS, thus eliminating the need for specialized equipment such as local exhaust ventilation systems and increasing productivity. Furthermore, since the film-coated substrate 1 is provided with a multilayer film 3, its weather resistance can also be improved.

[0056] In this embodiment, in the second layer 5, the ratio of the total thickness of the low refractive index film 7 to the total thickness of the high refractive index film 8 (low refractive index film 7 / high refractive index film 8) is preferably 2.2 or more, more preferably 5 or more, even more preferably 7 or more, particularly preferably 9 or more, preferably 15 or less, more preferably 13 or less, even more preferably 10 or less, and particularly preferably 9.5 or less. When the ratio (low refractive index film 7 / high refractive index film 8) is within the above range, the infrared transmittance can be increased even more effectively.

[0057] The film-coated substrate 1 of this embodiment can effectively increase infrared transmittance by using a multilayer film 3, which is an anti-reflective film, and is therefore suitable for use in infrared-transmitting lenses. In particular, it is more suitable for use in night vision camera lenses for human detection.

[0058] (reflective film) In the present invention, the multilayer film 3 may be a reflective film. Such a reflective film can be produced, for example, by adjusting the film thickness and number of layers of the low refractive index film 7 and high refractive index film 8 that constitute the multilayer film 3. Furthermore, when the multilayer film 3 is a reflective film, the film-coated substrate 1 can be suitably used as a reflective mirror or the like. In this case, the substrate 2 may be made of optical glass that absorbs in the infrared region, such as borosilicate glass or quartz glass.

[0059] The film thickness per layer of the low refractive index film 7 is not particularly limited, but is preferably 1000 nm or more, more preferably 1400 nm or more, preferably 2000 nm or less, and more preferably 1600 nm or less.

[0060] The thickness of each layer of the high refractive index film 8 is not particularly limited, but is preferably 300 nm or more, more preferably 450 nm or more, more preferably 700 nm or less, and more preferably 600 nm or less.

[0061] The overall thickness of the second layer 5 is not particularly limited, but is preferably 8000 nm or more, more preferably 9000 nm or more, preferably 13000 nm or less, and more preferably 12000 nm or less.

[0062] Furthermore, the total number of layers in the film constituting the second layer 5 is preferably 7 or more, more preferably 9 or more, more preferably 19 or fewer, and more preferably 15 or fewer.

[0063] (Optical filter film) In the present invention, the multilayer film 3 may be an optical filter film. Such an optical filter film can be manufactured, for example, by adjusting the film thickness and number of layers of the low refractive index film 7 and high refractive index film 8 that constitute the multilayer film 3. Furthermore, when the multilayer film 3 is an optical filter film, the film-coated substrate 1 can be suitably used as an optical filter or the like that can selectively transmit infrared rays with wavelengths of 8 μm to 14 μm. In this case, the substrate 2 may be made of glass or the like that which has optical properties, such as quartz glass or borosilicate glass.

[0064] The film thickness per layer of the low refractive index film 7 is not particularly limited, but is preferably 400 nm or more, more preferably 800 nm or more, preferably 1700 nm or less, and more preferably 1600 nm or less.

[0065] The number of layers of the low refractive index film 7 constituting the second layer 5 is preferably 10 or more, more preferably 14 or more, preferably 20 or fewer, and more preferably 18 or fewer.

[0066] The thickness of each layer of the high refractive index film 8 is not particularly limited, but is preferably 80 nm or more, more preferably 200 nm or more, preferably 350 nm or less, and more preferably 300 nm or less.

[0067] The number of layers of the high refractive index film 8 constituting the second layer 5 is preferably 9 or more, more preferably 13 or more, preferably 19 or fewer, and more preferably 17 or fewer.

[0068] The overall thickness of the second layer 5 is not particularly limited, but is preferably 12,000 nm or more, more preferably 15,000 nm or more, more preferably 24,000 nm or less, and more preferably 20,000 nm or less.

[0069] Furthermore, the total number of layers in the film constituting the second layer 5 is preferably 19 or more, more preferably 27 or more, more preferably 39 or fewer, and more preferably 35 or fewer.

[0070] The following describes an example of a method for manufacturing the film-coated substrate 1.

[0071] [Method for manufacturing a film-coated substrate] First, a substrate 2 is prepared. Next, a multilayer film 3 is formed on the first main surface 2a of the substrate 2. The multilayer film 3 can be formed by stacking a first layer 4, a second layer 5, and a third layer 6 in that order on the first main surface 2a of the substrate 2.

[0072] Specifically, the first layer 4 can be formed, for example, by a vapor deposition method or a sputtering method. Examples of vapor deposition methods include vacuum deposition, ion plating vacuum deposition, or ion-assisted vacuum deposition. Among these, it is preferable to form the first layer 4 by ion-assisted vacuum deposition.

[0073] When forming the first layer 4 by vacuum deposition, for example, the material for the first layer 4 is used as the deposition source, the substrate temperature is set to 100°C to 130°C, and the vacuum level is set to 1 × 10⁻⁶. -2 Pa~2×10 -2 By setting the density to Pa and the deposition rate to 0.3 nm / sec to 0.5 nm / sec, the film can be deposited as an adhesion layer.

[0074] When the first layer 4 is Y2O3, it is preferable to form the first layer 4 such that the film structure on the substrate 2 side is relatively sparse and the film structure on the second layer 5 side is relatively dense. In this case, the film stress caused by the second layer 5 can be further reduced, and peeling of the film from the substrate 2 can be made even less likely.

[0075] Such a film structure of the first layer 4 can be formed, for example, by irradiating the film with ions using ion-assisted vacuum deposition during the deposition of the first layer 4. In this case, it is desirable to form the first layer 4 by first forming a relatively sparse film structure through normal deposition, and then irradiating with ions to form a relatively dense film structure when the deposition has progressed 30% to 50%. Furthermore, by using Y2O3 as the material for the first layer 4, the above film structure can be formed even more easily. In addition, when using Si as the material for the first layer 4, a dense film structure can be formed even without ion assistance during deposition.

[0076] The second layer 5 can be formed by laminating a low refractive index film 7 and a high refractive index film 8 on the first main surface 2a of the substrate 2.

[0077] The low refractive index film 7 and the high refractive index film 8 can be formed, for example, by vapor deposition or sputtering. Examples of vapor deposition methods include vacuum deposition, ion plating vacuum deposition, or ion-assisted vacuum deposition.

[0078] When forming a low refractive index film 7 by vacuum deposition, for example, the material for the low refractive index film 7 is used as the deposition source, the substrate temperature is set to 100°C to 130°C, and the vacuum level is set to 1 × 10⁻⁶. -4 Pa~7×10 -4 By setting the density to Pa and the deposition rate to 0.1 nm / sec to 0.5 nm / sec, it is possible to deposit an anti-reflective film.

[0079] When forming a high refractive index film 8 by vacuum deposition, for example, the material for the high refractive index film 8 is used as the deposition source, the substrate temperature is set to 100°C to 130°C, and the vacuum level is set to 1 × 10⁻⁶.-4 Pa~7×10 -4 By setting the density to Pa and the deposition rate to 10 nm / sec to 30 nm / sec, it is possible to deposit an anti-reflective film.

[0080] In particular, when the low refractive index film 7 is composed of YF3, it is preferable to set the film deposition rate to 0.5 nm / sec or less, and more preferably to 0.3 nm / sec or less. In this case, the separation of yttrium (Y) and fluorine (F) can be further suppressed, and the decrease in infrared transmittance due to fluorine deficiency can be further suppressed, which is particularly effective when deposition is performed using an electron gun. To further suppress the separation of yttrium (Y) and fluorine (F) in YF3, it is preferable to perform film deposition using an indirect heating method with a resistance heating source or a bombard evaporation source. However, in the case of an indirect heating method, the film deposition rate is not limited to this because the decomposition of the deposition material can be suppressed.

[0081] The third layer 6 can be formed, for example, by a vapor deposition method or a sputtering method. Examples of vapor deposition methods include vacuum deposition, ion plating vacuum deposition, or ion-assisted vacuum deposition. Among these, the third layer 6 is preferably formed by ion-assisted vacuum deposition.

[0082] For example, when forming the third layer 6 by vacuum deposition, the material for the third layer 6 is used as the deposition source, the substrate temperature is set to 100°C to 130°C, and the vacuum level is set to 1 × 10⁻⁶. -2 Pa~2×10 -2 By setting the density to Pa and the deposition rate to 0.3 nm / sec to 0.5 nm / sec, a protective layer can be deposited. In addition, in ion-assisted vacuum deposition, oxygen ions are used as the irradiated ions.

[0083] When forming the third layer 6, it is preferable to deposit the third layer 6 so that it forms a dense film structure. In this case, weather resistance and scratch resistance can be further improved.

[0084] When Y2O3 is used for the third layer 6, it is preferable to deposit the third layer 6 such that the film structure on the second layer 5 side is relatively sparse and the film structure on the outermost layer side is relatively dense. In this case, the film stress caused by the third layer 6 can be further reduced, and delamination from the second layer 5 can be made even less likely.

[0085] Such a third layer 6 film structure can be formed, for example, by irradiating the film with ions using ion-assisted vacuum deposition during the deposition of the third layer 6. In this case, it is desirable to form the third layer 6 by first forming a relatively sparse film structure through normal deposition, and then irradiating with oxygen ions to form a relatively dense film structure when the deposition has progressed 30% to 50%. Furthermore, by using Y2O3 as the material for the third layer 6, the above film structure can be formed even more easily. In addition, when using Si as the material for the third layer 6, a dense film structure can be formed even without ion assistance during deposition.

[0086] Furthermore, when forming the first layer 4 to the third layer 6, it is preferable to form the multilayer film 3 so that it has compressive stress. In this case, delamination of the multilayer film 3 from the substrate 2 can be further suppressed. A multilayer film 3 having compressive stress can be formed mainly by adjusting the film formation rate when forming the first layer 4 to the third layer 6.

[0087] The present invention will be described in more detail below based on specific examples. The present invention is not limited in any way to the following examples, and can be implemented with appropriate modifications without changing its essence.

[0088] (Example 1) As a glass composition, raw materials were formulated to have a composition of 20% Ge, 15% Ga, and 65% Te in mol%, and a raw material batch was obtained. Next, a quartz glass ampoule washed with pure water was evacuated while being heated, and then the raw material batch was put in, and the quartz glass ampoule was sealed with an oxygen burner while evacuating. The sealed quartz glass ampoule was heated to 800 °C at a rate of 50 °C / hour in a melting furnace and then held for 9 hours. During the holding time, the quartz glass ampoule was inverted up and down every hour to stir the melt. Then, the quartz glass ampoule was taken out of the melting furnace and quenched to room temperature to obtain a glass base material. The obtained glass base material was cut and polished, processed into a disk shape with a diameter of 15 mm and a thickness of 2 mm, and then both sides were optically polished to obtain a substrate (chalcogenide glass).

[0089] Next, on one main surface of the obtained substrate, a multilayer film, which is an antireflection film, was formed by a vacuum deposition method. Specifically, Y2O3 was used as a deposition source, the vacuum degree was 1.5×10 -2 Pa, the film formation rate was 0.5 nm / sec, and as an adhesion layer, a Y2O3 film as the first layer was formed on one main surface of the substrate. When forming the Y2O3 film, after the film formation progressed 40%, the film was formed while irradiating oxygen ions by an ion assist method.

[0090] Next, YF3 was used as a deposition source, the vacuum degree was 5×10 -4 Pa, the film formation rate was 0.3 nm / sec, and as an antireflection film, a YF3 film as a low refractive index film was formed on the first layer. Subsequently, Ge was used as a deposition source, the vacuum degree was 5×10 -4 Pa, the film formation rate was 20 nm / sec, and as an antireflection film, a Ge film as a high refractive index film was formed on the YF3 film. By repeating this operation, a second layer having a total of 6 layers of films in which YF3 films and Ge films were alternately laminated one by one on the Y2O3 film was formed.

[0091] Next, Y2O3 was used as a deposition source, the vacuum degree was 1.5×10 -2A Y2O3 film was deposited as a third layer on top of the second layer as a protective layer, using a deposition rate of 0.3 nm / sec at Pa. The Y2O3 film was deposited while irradiating with oxygen ions using an ion-assisted method after 40% of the film deposition had progressed.

[0092] As described above, the film-coated substrate of Example 1 was obtained. The substrate temperature was maintained at 120°C during film formation. The film thickness of each layer is as shown in Table 1 below. In Table 1 below, layers 1 to 8 indicate the layer number from the substrate side.

[0093] (Examples 2-10) The film-coated substrates of Examples 2 to 10 were obtained in the same manner as in Example 1, except that the film thickness of each layer was changed to match the film thickness shown in Table 1 below. In Example 3, the second layer was deposited in a total of 4 layers, as shown in Table 1 below. In Example 4, the second layer was deposited in a total of 3 layers, as shown in Table 1 below.

[0094] (Example 11) A multilayer anti-reflective film was deposited on one main surface of the substrate obtained in the same manner as in Example 1 by vacuum deposition. Specifically, Si was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4 With a pressure of Pa and a deposition rate of 0.5 nm / sec, a Si film was deposited as the first layer on one main surface of the substrate to serve as the adhesion layer.

[0095] A second layer was formed on the obtained first layer in the same manner as in Example 1, except that the film thickness of each layer was changed to the film thickness shown in Table 1 below.

[0096] Next, using Si as the deposition source, the vacuum level was set to 5 × 10⁻⁶. -4 With a deposition rate of 0.5 nm / sec and a third Si film as a protective layer, the film was deposited on top of the second layer.

[0097] As described above, the film-coated substrate of Example 11 was obtained. The substrate temperature was maintained at 120°C during film formation. The film thickness of each layer is as shown in Table 1 below.

[0098] (Comparative Example 1) A multilayer film was deposited on one main surface of the substrate obtained in the same manner as in Example 1 by vacuum deposition. Specifically, Ge was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4 Using a vacuum of Pa and a deposition rate of 20 nm / sec, a Ge film, as a high refractive index film, was deposited on one main surface of the substrate as an adhesion layer. Subsequently, a YF3 was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4 A low refractive index YF3 film was deposited on a Ge film as an anti-reflective coating, using a film deposition rate of 0.3 nm / sec at a pressure of Pa. By repeating this operation, a film-coated substrate of Comparative Example 1 was formed, having a total of six layers of film, with one layer of Ge film and one layer of YF3 film alternately laminated on one main surface of the substrate. The substrate temperature was maintained at 120°C during film deposition. The film thickness of each layer is shown in Table 1 below.

[0099] [evaluation] (Infrared transmittance) The transmission spectra of the film-coated substrates obtained in Examples 1 to 11 and Comparative Example 1 were measured using an FT-IR (Fourier Transform Infrared Spectrophotometer).

[0100] Figure 2 shows the transmission spectrum of the film-coated substrate obtained in Example 1 at wavelengths of 3000 nm to 14000 nm. Figure 3 shows the transmission spectrum of the film-coated substrate obtained in Example 1 and Comparative Example 1 at wavelengths of 7000 nm to 14000 nm.

[0101] Figure 3 shows that the film-coated substrate obtained in Example 1 exhibits higher transmittance compared to Comparative Example 1, particularly in the infrared region with wavelengths of 8000 nm (8 μm) to 14000 nm (14 μm).

[0102] Similarly, the transmission spectra of the film-coated substrates obtained in Examples 2 to 11 were measured, and the average infrared transmittance in the wavelength range of 8 μm to 14 μm was determined.

[0103] The results are shown in Table 1 below. Table 1 also shows the film thickness ratio (YF3 / Ge), which is the ratio of the total film thickness of the low-refractive-index film (YF3 film) to the total film thickness of the high-refractive-index film (Ge film).

[0104] [Table 1]

[0105] Table 1 shows that the film-coated substrates obtained in Examples 1 to 11 exhibit higher average infrared transmittance in the 8 μm to 14 μm wavelength range compared to Comparative Example 1. In Comparative Example 1, the outermost layer was made of YF3, which has poor weather resistance, and it is thought that exposure to air after film formation caused a decrease in transmittance. In addition, the thickness of the Ge layer resulted in significant absorption loss, leading to a decrease in transmittance.

[0106] (Example 12) A multilayer reflective film was deposited on one main surface of the substrate obtained in the same manner as in Example 1 by vacuum deposition. Specifically, Ge was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4 With a pressure of Pa and a deposition rate of 20 nm / sec, a Ge film was deposited as the first layer on one main surface of the substrate to serve as the adhesion layer.

[0107] Next, using YF3 as the deposition source, the vacuum level was set to 5 × 10⁻⁶. -4 Using Pa and a deposition rate of 0.3 nm / sec, a YF3 film, a low refractive index film, was deposited on the first layer as a reflective film. Subsequently, Ge was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4 Using Pa and a deposition rate of 20 nm / sec, a Ge film, acting as a high refractive index film, was deposited on a YF3 film as a reflective film. By repeating this operation, a second layer was formed on the Ge film, consisting of a total of nine layers, with YF3 films and Ge films alternately stacked one layer at a time.

[0108] Next, using Ge as the deposition source, the vacuum level was set to 5 × 10⁻⁶. -4 The film deposition rate was set to Pa, and the deposition rate was set to 20 nm / sec. A third layer, a Ge film, was deposited on top of the second layer as the outermost layer of the reflective film.

[0109] As described above, a film-coated substrate of Example 12 was obtained. The substrate temperature was maintained at 120°C during film formation. The film thickness of each layer is as shown in Table 2 below. In Table 2 below, layers 1 to 11 indicate the layer number from the substrate side.

[0110] [Table 2]

[0111] Figure 4 shows the reflectance spectrum of the film-coated substrate obtained in Example 12 at wavelengths of 6000 nm to 14000 nm. As shown in Figure 4, the film-coated substrate obtained in Example 12 exhibits high reflectance, particularly in the infrared region around wavelengths of 8000 nm (8 μm) to 14000 nm (14 μm). The reflectance spectrum was measured using FT-IR (Fourier Transform Infrared Spectrophotometer).

[0112] (Example 13) A multilayer film, which is an optical filter film, was deposited on one main surface of the substrate obtained in the same manner as in Example 1 by vacuum deposition. Specifically, YF3 was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4 With a pressure of Pa and a deposition rate of 0.3 nm / sec, a YF3 film was deposited as the first layer on one main surface of the substrate to serve as the adhesion layer.

[0113] Next, using Ge as the deposition source, the vacuum level was set to 5 × 10⁻⁶. -4 Using a vacuum of Pa and a deposition rate of 20 nm / sec, a Ge film as a high refractive index film was deposited on the first layer as an optical filter film. Subsequently, a YF3 was used as the deposition source, and the vacuum level was set to 5 × 10⁻⁶. -4Using Pa and a deposition rate of 0.3 nm / sec, a YF3 film, which is a low refractive index film, was deposited on a Ge film as an optical filter film. By repeating this operation, a second layer was formed on the YF3 film, consisting of a total of 29 layers, in which Ge films and YF3 films were alternately stacked one layer at a time.

[0114] Next, using YF3 as the deposition source, the vacuum level was set to 5 × 10⁻⁶. -4 A YF3 film was deposited as a third layer on top of the second layer, using a pressure of Pa and a deposition rate of 0.3 nm / sec.

[0115] As described above, the film-coated substrate of Example 13 was obtained. The substrate temperature was maintained at 120°C during film formation. The film thickness of each layer is as shown in Table 3 below. In Table 3 below, layers 1 to 31 indicate the layer number from the substrate side.

[0116] [Table 3]

[0117] Figure 5 shows the transmission spectrum of the film-coated substrate obtained in Example 13 at wavelengths of 4000 nm to 14000 nm. As shown in Figure 5, the film-coated substrate obtained in Example 13 shows selectively increased transmittance, particularly in the infrared region at wavelengths of 8000 nm (8 μm) to 14000 nm (14 μm). The transmission spectrum was measured using FT-IR (Fourier Transform Infrared Spectrophotometer). [Explanation of symbols]

[0118] 1…Membrane-coated substrate 2...Base material 2a...First main surface 2b...Second main surface 3...Multilayer film 4…First layer 5…Second layer 6…The third layer 7... Low refractive index film 8…High refractive index film

Claims

1. A coated substrate having an anti-reflective coating made of multiple layers on the substrate, The anti-reflective coating, A first layer, which is an adhesive layer, is provided on the main surface of the substrate, A second layer is provided on the first layer and has a low refractive index film with a relatively low refractive index and a high refractive index film with a relatively high refractive index. The third layer, which is the outermost layer, is provided on the second layer mentioned above. Equipped with, The aforementioned anti-reflective coating does not contain ZnS in any of its layers. In the second layer, the low refractive index film and the high refractive index film are alternately laminated. In the second layer, the ratio of the total thickness of the low refractive index film to the total thickness of the high refractive index film (low refractive index film / high refractive index film) is 7 or more and 13 or less. The low refractive index film is YF ３ and YbF ３ It consists of at least one of the following: The aforementioned high refractive index film is made of Ge, A film-coated substrate in which the third layer is made of Si.

2. The first layer is Y ２ O ３ A film-coated substrate according to claim 1, comprising at least one of and Si.

3. The low refractive index film is YF ３ A film-coated substrate according to claim 1 or 2, comprising the above.

4. The film-coated substrate according to any one of claims 1 to 3, wherein the substrate is made of chalcogenide glass.

5. A film-coated substrate according to any one of claims 1 to 4, used in infrared-transmitting lenses.

6. A method for producing a film-coated substrate according to any one of claims 1 to 5, The steps include forming the first layer on the main surface of the substrate by vacuum deposition or sputtering, The process involves forming the second layer on the first layer by vacuum deposition or sputtering, The process involves forming the third layer on the second layer by vacuum deposition or sputtering, A method for manufacturing a film-coated substrate, comprising the following:

7. The method for manufacturing a film-coated substrate according to claim 6, wherein, in the step of forming the first layer, the first layer is formed such that the substrate side has a relatively sparse film structure and the second layer side has a relatively dense film structure.

8. A method for manufacturing a film-coated substrate according to claim 6 or 7, wherein in the step of forming the first layer, the first layer is formed by a vacuum deposition method, and from the middle of the film formation, the film is formed while irradiating with ions by an ion-assisted method.

9. A method for manufacturing a film-coated substrate according to any one of claims 6 to 8, wherein in the step of forming the second layer, the low refractive index film is formed by vacuum deposition under conditions that the film deposition rate is 0.5 nm / sec or less.

10. A method for manufacturing a film-coated substrate according to any one of claims 6 to 9, wherein in the step of forming the third layer, the third layer is formed by a vacuum deposition method, and from the middle of the film formation, the film is formed while irradiating with ions by an ion-assisted method.

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