JP2017129643A - Optical component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical component having a relatively large infrared ray transmittance while being capable of preventing scratches.SOLUTION: An optical component according to one embodiment of the present invention includes: a light-transmitting substrate; one or a plurality of intermediate layers deposited on at least one of an incident surface and an exit surface of the substrate; and a surface layer deposited on the outermost layer of the one or the plurality of intermediate layers and essentially comprising diamond-like carbon. The surface layer shows an indentation hardness of 5 GPa or more and 18 GPa or less. It is preferable that the component has the plurality of intermediate layers and that at least one of the plurality of intermediate layers essentially comprises diamond-like carbon. The substrate preferably essentially comprises a sintered body of zinc sulfide.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical component.

  Optical parts such as lenses formed of a material that transmits infrared rays are used in devices that use infrared rays, such as infrared sensors. As efficiency and performance of equipment using infrared rays increase, materials with higher infrared transmittance are required.

  Examples of the infrared transmitting material include zinc sulfide, zinc selenide, magnesium fluoride, sodium chloride, potassium chloride, lithium fluoride, silicon oxide, calcium fluoride, barium fluoride, and other dielectric materials such as silicon and germanium. A semiconductor can be mentioned. Among these materials, zinc sulfide is attracting attention as an infrared transmitting material because it can transmit a relatively large range of infrared bulk material in addition to transmitting a relatively wide infrared range of 0.4 μm to 14.4 μm. ing.

  However, since zinc sulfide has a relatively small hardness, for example, when used for a component that can come into contact with an external member such as an objective lens, there is a drawback that the surface is easily damaged. For this reason, there has been proposed an optical component that is less likely to be damaged by laminating a layer having a high hardness on the surface of a base material formed of zinc sulfide (see Japanese Patent Laid-Open No. 2015-224177).

  The optical component described in the above publication is scratched by forming a surface layer formed of diamond-like carbon on the outermost surface (incident surface or outgoing surface) of a base material mainly composed of a zinc sulfide sintered body. Suppressed. Furthermore, the optical component described in the above publication has a base material for suppressing a decrease in infrared transmittance due to oxidation of zinc sulfide due to the influence of ultraviolet rays and moisture during outdoor use, that is, to improve weather resistance. Disclosure of a plurality of intermediate layers between the layer and the surface layer is disclosed.

Japanese Patent Laying-Open No. 2015-224177

In the optical component disclosed in the above publication, a surface layer is formed of diamond-like carbon having a Knoop hardness of 2000 kg / mm ² (19.6 GPa) or more and 10,000 kg / mm ² (98 GPa) or less. Such diamond-like carbon has a low infrared transmittance as compared with a sintered body of zinc sulfide, and further improvement of the infrared transmittance is desired.

  This invention is made | formed based on the above situations, and makes it a subject to provide the optical component with a comparatively large infrared rays transmittance | permeability, while being able to prevent a damage | wound.

  An optical component according to an aspect of the present invention, which has been made to solve the above problems, includes a base material having translucency and one or more intermediate layers stacked on at least one of an incident surface and an output surface of the base material. And a surface layer mainly composed of diamond-like carbon, which is laminated on the outermost layer of the one or more intermediate layers, and the indentation hardness of the surface layer is 5 GPa or more and 18 GPa or less.

  The optical component according to one embodiment of the present invention has relatively high infrared transmittance while being able to prevent damage.

FIG. 1 is a schematic cross-sectional view showing the configuration of an optical component according to an embodiment of the present invention.

[Description of Embodiment of the Present Invention]
An optical component according to one embodiment of the present invention includes a base material having translucency, one or more intermediate layers stacked on at least one of an incident surface and an output surface of the base material, and the one or more intermediate layers. And a surface layer mainly composed of diamond-like carbon. The indentation hardness of the surface layer is 5 GPa or more and 18 GPa or less.

  Since the indentation hardness of the surface layer is within the above range, the optical component has a higher infrared transmittance than a conventional surface layer mainly composed of diamond-like carbon having a higher indentation hardness. Further, since the indentation hardness of the surface layer is within the above range, a sufficient damage prevention effect can be obtained in general use.

  A plurality of the intermediate layers are provided, and at least one of the plurality of intermediate layers is preferably composed mainly of diamond-like carbon. As described above, when a plurality of the intermediate layers are provided, and at least one intermediate layer of the plurality of intermediate layers has diamond-like carbon as a main component, the surface layer should be damaged or peeled by any chance. This diamond-like carbon-based intermediate layer can protect the substrate, effectively reducing the decrease in infrared transmittance even when used in harsh environments or for long periods of time. it can.

  The base material is preferably composed mainly of a zinc sulfide sintered body. Thus, when the base material contains a sintered body of zinc sulfide as a main component, the infrared transmittance is relatively large, and the production becomes relatively easy.

  Here, “translucent” means that the infrared transmittance is 60% or more, preferably 70% or more. The “infrared transmittance” is an average transmittance of infrared light having a wavelength of 8 μm or more and 12 μm or less, and is a value measured by a method according to JIS-B7107 (1997). The “indentation hardness” is a value measured based on JIS-Z2255 (2003), with the test force (pressing force of the indenter) being 200 mgf, and the holding time of this test force being 2 s. The “main component” means a component having the largest mass content, preferably a component containing 95% by mass or more.

[Details of the embodiment of the present invention]
Hereinafter, embodiments of an optical component according to the present invention will be described in detail with reference to the drawings.

  The optical component according to one embodiment of the present invention shown in FIG. 1 is a member intended to transmit light, specifically infrared light, and is, for example, a lens, a window material of an optical device (light incident port). Or it is used as a cover of the exit port).

  The optical component is laminated on a base material 1 having translucency and an incident surface or an emission surface of the substrate (usually, an emission surface in a light projecting unit and an incident surface in a light receiving unit of an apparatus using the optical component). 1 or a plurality of intermediate layers 2 (one case is illustrated in FIG. 1), and a surface layer 3 which is laminated on the outermost layer of the intermediate layer 2 and has diamond-like carbon as a main component.

  In the optical component, the lower limit of the indentation hardness of the surface layer 3 is 5 GPa, preferably 8 GPa, and more preferably 10 GPa. On the other hand, the upper limit of the indentation hardness of the surface layer 3 is 18 GPa, preferably 17 GPa, and more preferably 16 GPa. When the indentation hardness of the surface layer 3 is less than the lower limit, the outer surface may be easily damaged. Conversely, when the indentation hardness of the surface layer 3 exceeds the above upper limit, the infrared transmittance may be insufficient.

<Base material>
The substrate 1 is a member that substantially defines the optical function of the optical component, and is also a mechanical structure. Therefore, the shape of the base material 1 is arbitrarily selected according to demands such as an optical function, mechanical strength, and an attachment structure to an optical device.

The main component of the substrate 1 may be any material that has translucency, specifically, that transmits infrared rays. For example, zinc sulfide (ZnS), zinc selenide (ZnSe), magnesium fluoride (MgF) ₂ ), dielectrics such as sodium chloride (NaCl), potassium chloride (KCl), lithium fluoride (LiF), silicon oxide (SiO ₂ ), calcium fluoride (CaF ₂ ), barium fluoride (BaF ₂ ), For example, a semiconductor such as silicon or germanium can be used. Especially, as a main component of the base material 1, zinc sulfide with comparatively large infrared transmittance is preferable.

  When the base material 1 is mainly composed of zinc sulfide, it may be formed by chemical vapor deposition (CVD), but by forming it by sintering relatively inexpensive zinc sulfide powder, the manufacturing cost is reduced. Can be suppressed. That is, the base material 1 is preferably a sintered body made of a material mainly composed of zinc sulfide. In other words, as the main component of the substrate 1, a sintered body of zinc sulfide is preferable.

  The base material 1 whose main component is a sintered body of zinc sulfide includes a step of forming a zinc sulfide powder, a step of pre-sintering the formed body, and a step of pressure-sintering the pre-sintered body. It can form by the method of providing.

  As the zinc sulfide powder forming the sintered body of zinc sulfide, it is preferable to use one having an average particle size of 1 μm to 3 μm and a purity of 95% by mass or more. Such zinc sulfide powder can be obtained by a known powder synthesis method such as a coprecipitation method. The “average particle size” is a particle size at which the volume integrated value is 50% in the particle size distribution measured by the laser diffraction method.

  In the molding step, a molded body having a schematic shape according to the optical component to be finally obtained is formed by press molding using a mold. The mold is formed of a hard material such as cemented carbide or tool steel. Moreover, this shaping | molding process can be performed using a uniaxial press machine etc., for example.

  In the preliminary sintering step, the molded body produced in the molding step is heated, for example, in a vacuum atmosphere of 30 Pa or less or in an inert atmosphere such as nitrogen gas at atmospheric pressure. The presintering temperature can be 500 ° C. or more and 1000 ° C. or less, and the presintering time (presintering temperature holding time) can be 0.5 hours or more and 15 hours or less. The pre-sintered body obtained in this pre-sintering step has a relative density of 55% or more and 80% or less.

  In the pressure sintering step, the presintered body is heated while being pressed with a press die to obtain a sintered body (base material 1) having a desired shape. Specifically, as the press mold, for example, a pair of molds (upper mold and lower mold) having a constrained surface (cavity) formed of glassy carbon and mirror-polished can be used. The pressure sintering temperature is preferably 550 ° C. or higher and 1200 ° C. or lower. The sintering pressure is preferably 10 MPa or more and 300 MPa or less. Moreover, as sintering time, 1 minute or more and 60 minutes or less are preferable.

  The sintered body obtained in this pressure sintering step may be used as the base material 1 as it is, but as the base material 1 by performing a finishing process such as polishing of the incident surface and the outgoing surface as necessary. May be used.

<Intermediate layer>
The intermediate layer 2 is a functional layer formed between the base material 1 and a surface layer 3 to be described later. For example, improvement in adhesion of the surface layer 3, antireflection in the used wavelength band, protection of the base material 1, etc. It is a layer formed for the purpose. In addition, the intermediate layer 2 has a light-transmitting property so as not to inhibit the infrared light incident / exit of the substrate 1.

Examples of the main component of the intermediate layer 2 include silicon (Si), germanium (Ge), diamond-like carbon, gallium phosphide (GaP), boron phosphide (BP), yttrium oxide (Y ₂ O ₃ ), aluminum oxide ( Al ₂ O ₃ ), titanium oxide (TiO ₂ ), yttrium fluoride (YF ₃ ), lanthanum fluoride (LaF ₃ ), cerium fluoride (CeF ₃ ), magnesium fluoride (MgF ₂ ), zinc selenide (ZnSe) ), Diamond-like carbon and the like.

  In particular, as the main component of the intermediate layer 2 adjacent to the surface layer 3, silicon having relatively excellent adhesion and weather resistance is preferable.

  The lower limit of the average thickness of each intermediate layer 2 is preferably 5 nm, more preferably 50 nm. On the other hand, the upper limit of the average thickness of each intermediate layer 2 is preferably 200 μm and more preferably 5 μm. If the average thickness of each intermediate layer 2 is less than the lower limit, the manufacturing error may increase. On the contrary, when the average thickness of each intermediate layer 2 exceeds the upper limit, the infrared transmittance of the optical component may be unnecessarily lowered.

  The optical component preferably includes a plurality of intermediate layers 2. In this case, it is preferable that at least one intermediate layer 2 of the plurality of intermediate layers 2 has diamond-like carbon as a main component. The intermediate layer 2 containing diamond-like carbon as a main component can fulfill the function of protecting the substrate 1 in place of the surface layer 3 in the event that the surface layer 3 is damaged. The intermediate layer 2 mainly composed of diamond-like carbon is preferably laminated on another layer via the intermediate layer 2 mainly composed of silicon or germanium having excellent adhesion.

  The diamond-like carbon that can be the main component of the intermediate layer 2 is carbon having an amorphous structure having both sp3 bonds that are diamond structures and sp2 bonds that are graphite structures.

  The intermediate layer 2 formed of a material other than diamond-like carbon can be formed by a known method such as a sputtering method, a vacuum evaporation method, an ion plating method, a CVD method, or a plasma CVD method. The intermediate layer 2 formed of diamond-like carbon can be formed by a known method such as a plasma CVD method, a hot filament method, an ion plating method, a sputtering method, or an ion beam method.

<Surface layer>
The surface layer 3 is a protective layer for improving the scratch resistance of the optical component, that is, preventing damage to the substrate 1. Further, the surface layer 3 has translucency so as not to inhibit the infrared light incident / exit of the substrate 1.

  The diamond-like carbon that is the main component of the surface layer 3 is an amorphous (amorphous) carbon having both sp3 bonds that are diamond structures and sp2 bonds that are graphite structures.

  Diamond-like carbon is a material having various physical properties depending on the ratio of sp3 bonds and sp2 bonds contained therein, the ratio of hydrogen atoms in the structure, the presence or absence of other elements in the structure, and the like. Generally, the physical properties of diamond-like carbon are closer to diamond as the sp3 bond ratio is higher, and closer to graphite as the sp2 bond ratio is higher. Further, the physical properties of diamond-like carbon show characteristics close to that of a polymer when the ratio of the hydrogen atoms contained is increased.

  Such diamond-like carbon generally has ta-C (tetrahedral amorphous carbon), a-C (amorphous carbon), ta-C: H (based on sp3 bond, sp2 bond and hydrogen content. Hydrogenated tetrahedral amorphous carbon) and aC: H (hydrogenated amorphous carbon). The diamond-like carbon that is the main component of the surface layer 3 may be the same as or different from the diamond-like carbon that is the main component of the intermediate layer 2.

The ratio of sp3 bond to sp2 bond in diamond-like carbon is determined by the peak value near the wave number of 1330 cm ⁻¹ generated by sp3 bond in the spectrum measured by the laser Raman measurement method based on JIS-K0137 (2010) and the sp2 bond. It can be measured as a ratio (hereinafter referred to as ID / IG ratio) with the peak value in the vicinity of the generated wave number of 1550 cm ⁻¹ .

  In the optical component, the surface layer 3 has an indentation hardness in the range described above. For this reason, as an upper limit of ID / IG ratio of the surface layer 3, 1.2 is preferable and 1.0 is more preferable. That is, when the ID / IG ratio of the surface layer 3 exceeds the above upper limit, the indentation hardness may exceed the above range and the infrared transmittance may decrease.

  As a minimum of average thickness of surface layer 3, 20 nm is preferred and 100 nm is still more preferred. On the other hand, the upper limit of the average thickness of the surface layer 3 is preferably 200 μm, and more preferably 10 μm. If the average thickness of the surface layer 3 is less than the lower limit, the strength of the surface layer 3 may be insufficient. Conversely, when the average thickness of the surface layer 3 exceeds the upper limit, the infrared transmittance of the optical component may be unnecessarily lowered.

  The surface layer 3 can be formed by a known method such as a sputtering method, a vacuum deposition method, an ion plating method, a CVD method, or a plasma CVD method.

  The indentation hardness of the surface layer 3 varies depending on various conditions such as the method of forming the surface layer 3 and the raw material. For example, the pressure in the apparatus during film formation in the plasma CVD method or the deposition of excited ions is applied. It can adjust with the bias voltage made to collide with material (base material 1 and intermediate | middle layer 2).

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  In the optical component, an intermediate layer and a surface layer may be laminated on both the entrance surface and the exit surface. The optical component may further include a configuration other than the above, for example, a light diffusion layer, a reflective layer, a filter layer, a polarizing layer, and the like.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

  Production examples 1 to 20 of the optical component will be described. Production Examples 1 to 20 of the optical component include a base material having a material and design thickness shown in Table 1, a plurality of intermediate layers, and a surface layer.

<Production Example 1>
In Production Example 1, a base material made of a disk-shaped zinc sulfide sintered body, first to fourth intermediate layers sequentially stacked on the surface of the base material, and further stacked on the surface of the fourth intermediate layer A surface layer.

(Base material)
The base material was produced in the following procedure. First, a zinc sulfide powder having an average particle diameter of 2 μm and a purity of 98% by mass was molded by a uniaxial mold press (cold press) to produce a disk-shaped molded body having a diameter of 20 mm and an average thickness of 5 mm. . Next, the obtained molded body was heated to 800 ° C. in a nitrogen atmosphere and held for 5 hours to obtain a pre-sintered body having a relative density of about 60%. The pre-sintered body is placed between a pair of molds (upper mold and lower mold) made of glassy carbon and having a mirror-polished constraining surface, and heated to 1000 ° C. while being pressurized at a pressure of 50 MPa. For 300 seconds, a substrate having a diameter of 20 mm and an average thickness of 3 mm was obtained.

(First intermediate layer)
As the first intermediate layer, silicon was laminated by setting conditions such that the average thickness was 289 nm by a vacuum deposition method using an electron beam.

(Second intermediate layer)
As the second intermediate layer, methane gas was used as a raw material, and diamond-like carbon was laminated by setting conditions such that the average thickness was 150 nm by a high frequency plasma CVD method of 13.56 MHz.

(3rd intermediate layer)
As the third intermediate layer, silicon was laminated by setting the conditions such that the average thickness was 70 nm by a vacuum deposition method using an electron beam.

(4th intermediate layer)
As the fourth intermediate layer, germanium was laminated under a condition that the average thickness was 837 nm by a vacuum deposition method using an electron beam.

(Surface layer)
As a surface layer, diamond-like carbon was laminated by setting conditions such that the average thickness was 1100 nm by a high frequency plasma CVD method of 13.56 MHz using methane gas as a raw material and an internal pressure of 20 Pa.

<Production Example 2>
Production Example 2 was prototyped under the same conditions as in Production Example 1 except that the internal pressure of the apparatus at the time of stacking the surface layers was 10 Pa.

<Production Example 3>
Production Example 3 was prototyped under the same conditions as in Production Example 1 except that the internal pressure of the apparatus when the surface layer was laminated was 5 Pa.

<Production Example 4>
Production Example 4 was prototyped under the same conditions as in Production Example 1 except that the internal pressure of the apparatus during lamination of the surface layer was 0.1 Pa.

<Production Example 5>
Production Example 5 includes the same base material as in Production Example 1, the first to fourth intermediate layers sequentially laminated on the surface of the base material, and the surface layer laminated on the surface of the fourth intermediate layer. Is.

(First intermediate layer)
As the first intermediate layer, silicon was laminated by setting conditions such that the average thickness was 200 nm by a vacuum deposition method using an electron beam.

(Second intermediate layer)
As the second intermediate layer, methane gas was used as a raw material, and diamond-like carbon was laminated by setting conditions such that the average thickness was 258 nm by a high frequency plasma CVD method of 13.56 MHz.

(3rd intermediate layer)
As the third intermediate layer, germanium was laminated under a condition that the average thickness was 866 nm by a vacuum deposition method using an electron beam.

(4th intermediate layer)
As the fourth intermediate layer, silicon was laminated by setting conditions such that the average thickness was 200 nm by a vacuum deposition method using an electron beam.

(Surface layer)
As a surface layer, diamond-like carbon was laminated by setting conditions such that the average thickness was 978 nm by a high frequency plasma CVD method of 13.56 MHz using methane gas as a raw material and an internal pressure of 20 Pa.

<Production Example 6>
Production Example 6 was prototyped under the same conditions as in Production Example 5 except that the internal pressure of the apparatus during lamination of the surface layer was 10 Pa.

<Production Example 7>
Production Example 7 was prototyped under the same conditions as in Production Example 5 except that the internal pressure of the apparatus at the time of stacking the surface layers was 5 Pa.

<Production Example 8>
Production Example 8 was prototyped under the same conditions as in Production Example 5 except that the internal pressure of the apparatus during lamination of the surface layer was 0.1 Pa.

<Production Example 9>
Production Example 9 includes the same base material as in Production Example 1, the first to fourth intermediate layers sequentially laminated on the surface of the base material, and the surface layer laminated on the surface of the fourth intermediate layer. .

(First intermediate layer)
As the first intermediate layer, silicon was laminated by setting conditions such that the average thickness was 103 nm by a vacuum deposition method using an electron beam.

(Second intermediate layer)
As the second intermediate layer, germanium was laminated by setting the conditions such that the average thickness was 70 nm by a vacuum deposition method using an electron beam.

(3rd intermediate layer)
As the third intermediate layer, methane gas was used as a raw material, and diamond-like carbon was laminated by setting conditions such that the average thickness was 150 nm by a high frequency plasma CVD method of 13.56 MHz.

(4th intermediate layer)
As the fourth intermediate layer, silicon was stacked under conditions set to an average thickness of 70 nm by vacuum deposition using an electron beam.

(Surface layer)
As a surface layer, diamond-like carbon was laminated by setting conditions such that the average thickness would be 1324 nm by high frequency plasma CVD at 13.56 MHz with methane gas as a raw material and an internal pressure of 20 Pa.

<Production Example 10>
Production Example 10 was prototyped under the same conditions as in Production Example 9 except that the internal pressure of the apparatus during lamination of the surface layer was 10 Pa.

<Production Example 11>
Production Example 11 was prototyped under the same conditions as in Production Example 9 except that the internal pressure of the apparatus during lamination of the surface layer was 5 Pa.

<Production Example 12>
Production Example 12 was prototyped under the same conditions as in Production Example 9 except that the internal pressure of the apparatus when the surface layer was laminated was 0.1 Pa.

<Production Example 13>
Production Example 13 includes the same base material as in Production Example 1, the first to third intermediate layers sequentially laminated on the surface of the base material, and the surface layer laminated on the surface of the third intermediate layer. .

(First intermediate layer)
As the first intermediate layer, silicon was laminated by setting conditions such that the average thickness was 267 nm by a vacuum deposition method using an electron beam.

(Second intermediate layer)
As the second intermediate layer, methane gas was used as a raw material, and diamond-like carbon was laminated by setting conditions such that the average thickness was 225 nm by a high frequency plasma CVD method of 13.56 MHz.

(3rd intermediate layer)
As the third intermediate layer, silicon was laminated by setting conditions such that the average thickness was 863 nm by vacuum deposition using an electron beam.

(Surface layer)
As a surface layer, diamond-like carbon was laminated by setting conditions such that the average thickness would be 1125 nm by high-frequency plasma CVD at 13.56 MHz using methane gas as a raw material and an internal pressure of 20 Pa.

<Production Example 14>
Production Example 14 was prototyped under the same conditions as in Production Example 13 except that the internal pressure of the apparatus during lamination of the surface layer was 10 Pa.

<Production Example 15>
Production Example 15 was prototyped under the same conditions as in Production Example 13 except that the internal pressure of the apparatus during lamination of the surface layer was 5 Pa.

<Production Example 16>
Production Example 16 was prototyped under the same conditions as in Production Example 13 except that the internal pressure of the apparatus during lamination of the surface layer was 0.1 Pa.

<Production Example 17>
Production Example 17 includes the same base material as in Production Example 1, the first to third intermediate layers sequentially laminated on the surface of the base material, and the surface layer laminated on the surface of the third intermediate layer. .

(First intermediate layer)
As the first intermediate layer, silicon was laminated by setting conditions such that the average thickness was 644 nm by a vacuum deposition method using an electron beam.

(Second intermediate layer)
As the second intermediate layer, germanium was laminated by setting conditions such that the average thickness was 535 nm by a vacuum vapor deposition method using an electron beam.

(3rd intermediate layer)
As the third intermediate layer, silicon was laminated by setting the conditions such that the average thickness was 94 nm by a vacuum deposition method using an electron beam.

(Surface layer)
As a surface layer, diamond-like carbon was laminated by setting conditions such that the average thickness was 1100 nm by a high frequency plasma CVD method of 13.56 MHz using methane gas as a raw material and an internal pressure of 20 Pa.

<Production Example 18>
Production Example 18 was prototyped under the same conditions as in Production Example 17 except that the internal pressure of the apparatus when the surface layer was laminated was 10 Pa.

<Production Example 19>
Production Example 19 was prototyped under the same conditions as in Production Example 17 except that the internal pressure of the apparatus at the time of stacking the surface layers was 5 Pa.

<Production Example 20>
Production Example 20 was prototyped under the same conditions as in Production Example 17 except that the internal pressure of the apparatus at the time of stacking the surface layers was 0.1 Pa.

<Evaluation>
For the optical component production examples 1 to 20, the surface layer is subjected to indentation hardness measurement, constant temperature and humidity test, and weather resistance test. In addition, the infrared transmittance after the weather resistance test was measured, the surface appearance after the constant temperature and humidity test was visually evaluated, and the surface appearance after the weather resistance test was visually evaluated.

(Indentation hardness measurement)
The indentation hardness was measured according to JIS-Z2255 (2003), with the test force (pressing force of the indenter) set to 200 mgf, and the holding time of this test force set to 2 s.

(Constant temperature and humidity test)
The constant temperature and humidity test was held for 240 hours at a temperature of 85 ° C. and a relative humidity of 95% in accordance with JIS-C60068-2-3 (1987).

(Weather resistance test)
In the weather resistance test, a sunshine carbon arc lamp (255 W / m ² ) was irradiated for 1000 hours in an environment of a temperature of 63 ± 3 ° C. and a humidity of 50 ± 5% in accordance with JIS-D0205 (1987).

(Infrared transmittance)
The infrared transmittance was measured as an average transmittance of infrared light having a wavelength of 8 μm or more and 12 μm or less by a method according to JIS-B7107 (1997).

(Appearance visual evaluation)
As for visual evaluation of the appearance, “A” indicates that there is no particular change compared with the initial state by visual inspection, “B” indicates that speckled peeling of the surface layer is confirmed, and relatively severe peeling. The thing was set to "C".

  The evaluation results are summarized in Table 2 below.

  As shown in the table, it can be confirmed that the infrared transmittance is improved by setting the indentation hardness of the surface layer to 18 GPa or less. Further, it can be confirmed that the weather resistance is improved by including a layer made of diamond-like carbon in the intermediate layer.

  The optical component according to the embodiment of the present invention can be suitably used as an objective lens for an infrared camera, for example.

1 base material 2 intermediate layer 3 surface layer

Claims (3)

A substrate having translucency,
One or more intermediate layers laminated on at least one of the incident surface and the exit surface of the substrate;
Laminated on the outermost layer of the one or more intermediate layers, and a surface layer mainly composed of diamond-like carbon,
An optical component having an indentation hardness of 5 GPa or more and 18 GPa or less of the surface layer.   The optical component according to claim 1, further comprising a plurality of the intermediate layers, wherein at least one of the plurality of intermediate layers includes diamond-like carbon as a main component. The optical component according to claim 1, wherein the base material contains a sintered body of zinc sulfide as a main component.

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