JP2019191203A - Optical component - Google Patents

Abstract

To provide an optical component that can suppress foreign matter from adhering to the surface, while being relatively inexpensive.SOLUTION: An optical component 1 has a translucent base material 2, one or more intermediate layer(s) 3 laminated on at least one of an incoming face and an outgoing face of the base material 2, and a surface layer 4 laminated on the outermost layer of the one or more intermediate layer(s) 3 and having diamond-like carbon as the main component, the surface layer 4 containing fluorine.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical component.

  An infrared camera that includes an infrared lens unit having an infrared lens and an infrared imaging device and captures an infrared image to generate image data is used in various applications. As an example, a night vision system that is mounted on a vehicle, images the surroundings of the vehicle with an infrared camera at night, detects a pedestrian with a possibility of collision, and issues a warning to the driver has been put into practical use.

  When an infrared camera is mounted on a vehicle, the infrared camera is usually mounted on the front of the vehicle, so foreign objects such as mud and dust adhere to the surface of the protective window and lens, and a clear image cannot be obtained. Problems can arise.

  Therefore, a technique for providing a wiper device (see JP 2013-81097 A), a technique for providing a blower device (see JP 2012-168457 A), and a cleaning device are provided to remove foreign matter adhering to the infrared camera. Techniques (see JP 2012-35654 A) and the like have been proposed.

  When the incidental equipment is provided in the infrared camera as described above, there is a disadvantage that the cost of the apparatus increases and the space occupied by the apparatus increases.

  In addition, in an optical device such as an infrared camera, optical parts such as a protective window and a lens may be fixed using screws, and may be in pressure contact with the surface of the optical part by rotating and rubbing another member. is there.

  In such a configuration, if the slidability of the surface of the optical component is small, the friction with the member to be rubbed increases, and the optical component may not be firmly fixed, and a gap is formed to reduce the airtightness. There is a fear.

JP2013-81097A JP 2012-168457 A JP 2012-35654 A

  The present invention has been made based on the above-described circumstances, and it is an object of the present invention to provide an optical component that can suppress the adhesion of foreign matters to the surface while being relatively inexpensive and has excellent slidability. And

  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. A layer 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 surface layer contains fluorine.

  The optical component according to one embodiment of the present invention can suppress adhesion of foreign matters to the surface while being relatively inexpensive, and is excellent in slidability.

FIG. 1 is a schematic cross-sectional view showing the configuration of an optical component according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a lens unit including the optical component of FIG.

[Description of Embodiment of the Present Invention]
An optical component according to one embodiment of the present invention includes a light-transmitting base material, 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 members. And a surface layer mainly composed of diamond-like carbon, and the surface layer contains fluorine.

  Since the main component of the surface layer is diamond-like carbon, the optical component is excellent in scratch resistance, and therefore can be disposed exposed on the front surface of the vehicle. Furthermore, the optical component contains fluorine, so that the surface free energy is small, adhesion of foreign matters can be suppressed, and the slidability is excellent.

  In the optical component, it is preferable that the fluorine content of the surface layer is larger on the outer surface side than on the inner surface side. As described above, the fluorine content of the surface layer is larger on the outer surface side than on the inner surface side, so that the deterioration of translucency is suppressed and the adhesion of foreign matters to the surface is effectively suppressed. Can be improved.

  In the optical component, the base material is preferably formed from a sintered body mainly composed of zinc sulfide. As described above, when the base material is formed of a sintered body containing zinc sulfide as a main component, even if the shape of the optical component is a complicated shape such as an aspheric lens, the optical component is relatively inexpensive. Can be manufactured.

  Here, the “main component” means a component having the largest mass content.

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

  FIG. 1 shows a configuration of an optical component 1 according to an embodiment of the present invention. The optical component 1 is a member intended to transmit light, specifically infrared light, and is used as, for example, a lens, a window material of an optical device (cover for a light incident port or light emission port), or the like. It is done. That is, it is contemplated that the optical component 1 is used in a portion exposed to the outside of the optical apparatus.

  The optical component 1 includes a base material 2 having translucency, and an incident surface or an output surface of the base material 2 (usually, an output surface in a light projecting unit and an input surface in a light receiving unit of the apparatus using the optical component 1). 1) or a plurality of intermediate layers 3 (FIG. 1 shows an example of a single layer), and a surface that is laminated on the outermost layer of this intermediate layer 3 and that contains diamond-like carbon as a main component and contains fluorine. Layer 4.

<Base material>
The substrate 2 is a member that substantially determines the optical function of the optical component 1 and is also a mechanical structure. Therefore, the shape of the base material 2 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 2 may be any material having translucency, specifically, a material 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 2, zinc sulfide having a relatively large infrared transmittance is preferable.

  In the case where the base material 2 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 2 is preferably a sintered body made of a material mainly composed of zinc sulfide. In other words, as the main component of the substrate 2, a sintered body of zinc sulfide is preferable.

  The base material 2 mainly composed of 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 1 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 2) 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 2 as it is, but as the base material 2 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 3 is a functional layer formed between the base material 2 and a surface layer 4 to be described later. For example, improvement in adhesion of the surface layer 4, antireflection in the used wavelength band, protection of the base material 2, etc. It is a layer formed for the purpose. In addition, the intermediate layer 3 has a light-transmitting property so as not to inhibit the infrared light incident / exit of the base material 2.

Examples of the main component of the intermediate layer 3 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) ) And the like.

  In particular, as the main component of the intermediate layer 3 adjacent to the surface layer 4, silicon having relatively excellent adhesion and weather resistance is preferable.

  The lower limit of the average thickness of each intermediate layer 3 is preferably 5 nm, and more preferably 50 nm. On the other hand, the upper limit of the average thickness of each intermediate layer 3 is preferably 200 μm and more preferably 5 μm. When the average thickness of each intermediate layer 3 is less than the above lower limit, the manufacturing error may increase. Conversely, when the average thickness of each intermediate layer 3 exceeds the upper limit, the infrared transmittance of the optical component 1 may be unnecessarily lowered.

  The optical component 1 preferably includes a plurality of intermediate layers 3. In this case, it is preferable that at least one intermediate layer 3 among the plurality of intermediate layers 3 is mainly composed of diamond-like carbon. The intermediate layer 3 containing diamond-like carbon as a main component can fulfill the function of protecting the substrate 2 in place of the surface layer 4 in the event that the surface layer 4 is damaged. The intermediate layer 3 mainly composed of diamond-like carbon is preferably laminated on another layer via the intermediate layer 3 mainly composed of silicon or germanium having excellent adhesion.

  As described above, the diamond-like carbon that can be the main component of the intermediate layer 3 is carbon having an amorphous structure that has both sp3 bonds that are diamond structures and sp2 bonds that are graphite structures. is there.

  The intermediate layer 3 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 3 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 4 is a protective layer for improving the scratch resistance of the optical component 1, that is, for preventing the base material 2 from being damaged. Further, the surface layer 4 has translucency so as not to hinder the incoming and outgoing infrared light of the base material 2.

  The surface layer 4 has a small surface free energy by containing fluorine. For this reason, the surface layer 4 is excellent in slidability and hardly adheres to foreign matters.

  The diamond-like carbon that is the main component of the surface layer 4 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 4 may be the same as or different from the diamond-like carbon that is the main component of the intermediate layer 3.

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 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 .

  The surface layer 4 may contain fluorine evenly throughout, but preferably contains fluorine so as to be unevenly distributed on the surface side. That is, the fluorine content of the surface layer 4 is preferably larger on the outer surface side than on the inner surface side (region close to the intermediate layer 3). In this way, by increasing the fluorine content of the surface layer 4 on the outer surface side, the surface layer 4 can be slidable on the surface of the optical component 1 while suppressing a decrease in light transmission and scratch resistance (hardness). And the adhesion of foreign matter to the surface of the optical component 1 can be effectively suppressed.

  The change in the fluorine content may be such that the fluorine content gradually increases toward the outer surface side according to the position of the surface layer 4 in the thickness direction. It may change. As an example, the surface layer 4 has a multilayer structure having a layer formed from diamond-like carbon containing no fluorine and a layer formed on the outer surface of the layer containing no fluorine and formed from diamond-like carbon containing fluorine. It may be said.

  The lower limit of the fluorine content on the outermost surface of the surface layer 4 is preferably 5 atomic%, and more preferably 10 atomic%. On the other hand, the upper limit of the fluorine content on the outermost surface of the surface layer 4 is preferably 50 atomic%, and more preferably 40 atomic%. When the fluorine content on the outermost surface of the surface layer 4 is less than the lower limit, there is a possibility that the adhesion of foreign matters to the outer surface of the surface layer 4 may not be sufficiently suppressed or the slidability of the surface layer 4 may be insufficient. is there. On the other hand, when the fluorine content on the outermost surface of the surface layer 4 exceeds the upper limit, the translucency of the surface layer 4 may be insufficient or the scratch resistance of the surface layer 4 may be insufficient.

  As a minimum of average thickness of surface layer 4, 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 4 is preferably 200 μm, and more preferably 10 μm. When the average thickness of the surface layer 4 is less than the above lower limit, the strength of the surface layer 4 may be insufficient. Conversely, when the average thickness of the surface layer 4 exceeds the above upper limit, the infrared transmittance of the optical component 1 may be unnecessarily lowered.

  When increasing the fluorine content on the outer surface side of the surface layer 4, the lower limit of the average thickness of the surface layer 4 containing 1 atomic% or more of fluorine is preferably 3% of the average thickness of the surface layer 4 5% is more preferable. On the other hand, 50% of the average thickness of the surface layer 4 is preferable and 40% is more preferable as the upper limit of the average thickness of the region containing 1 atomic% or more of the surface layer 4. In the surface layer 4, when the average thickness of a region containing 1 atomic% or more of fluorine is less than the lower limit, fluorine cannot be uniformly contained, and the slidability of the surface of the surface layer 4 cannot be sufficiently improved. There is a fear that the adhesion of foreign matters cannot be sufficiently suppressed. On the contrary, when the average thickness of the region containing 1 atomic% or more of fluorine in the surface layer 4 exceeds the above upper limit, the scratch resistance and translucency of the surface layer 4 may be lowered.

  The surface layer 4 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.

  By using a raw material containing fluorine as a carbon source (a raw material containing carbon) for generating diamond-like carbon by these methods, the surface layer 4 can contain fluorine.

  Specifically, as a raw material gas, for example, a well-known hydrocarbon gas used to form diamond-like carbon such as methane, benzene, toluene, etc., for example, fluoride such as perfluoromethane, hexafluoroethane, hexafluorobenzene, etc. By using a mixture of carbon gas, for example, a fluorinated hydrocarbon gas such as trifluorobenzene, the diamond-like carbon can contain fluorine.

  When the surface layer 4 is formed, the fluorine content of the raw material gas is gradually increased (the ratio of the fluorine-containing gas is increased) to gradually increase the fluorine content of the surface layer 4 toward the outer surface side. Can do.

  When the surface layer 4 has a multilayer structure, a step of forming a layer that does not contain fluorine using a source gas that does not contain fluorine, and a step of forming a layer that contains fluorine on the outer surface side of the layer that does not contain fluorine And may be performed after a time interval.

  Since the main component of the surface layer 4 is diamond-like carbon, the optical component 1 is excellent in scratch resistance, and thus can be arranged exposed on the front surface of the vehicle. Furthermore, the optical component 1 has a small surface free energy and excellent slidability due to the surface layer 4 containing fluorine, and can suppress adhesion of foreign matters. Moreover, since the surface layer 4 is excellent in slidability, the optical component 1 can easily remove foreign matters with a wiper or the like.

[Lens unit]
FIG. 2 shows an example of a lens unit including the optical component 1 of FIG. This lens unit includes an optical component 1 and a lens barrel 5 that holds the optical component 1.

  The lens barrel 5 includes a tube portion 6 and a cap portion 7 that is attached to the tip of the tube portion 6 and presses the outer edge portion of the surface layer 4 of the optical component 1 to fix it to the tube portion 6.

  The cylindrical portion 6 has a stepped portion 8 that locks the optical component 1 inside the distal end portion, and an external screw 9 is provided outside the distal end portion.

  The cap portion 7 includes an O-ring 10 that seals between the optical component 1 and an inner screw 11 that is screwed into the outer screw 9 of the cylindrical portion 6.

  The lens unit rotates the cap portion 7 around the optical axis to engage the inner screw 11 with the outer screw 9 of the cylindrical portion 6, and presses the O-ring 10 against the outer peripheral portion of the optical component 1. Is accurately fixed and the space between the lens barrel 5 and the optical component 1 is hermetically sealed.

  When the cap part 7 is tightened, the surface layer 4 of the optical component 1 contains fluorine and is excellent in slidability. Therefore, the friction between the O-ring 10 and the optical component 1 is small, and the O-ring 10 is deformed. Or being evenly compressed in the optical axis direction without being damaged, and the airtightness between the lens barrel 5 and the optical component 1 is improved.

[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 scope and meaning equivalent to the scope of the claims. The

  The method for manufacturing an optical component described in the above embodiment is an exemplification, and does not limit the method for manufacturing an optical component of the present invention.

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

DESCRIPTION OF SYMBOLS 1 Optical component 2 Base material 3 Intermediate | middle layer 4 Surface layer 5 Lens barrel 6 Cylinder part 7 Cap part 8 Step part 9 Outer screw 10 O-ring 11 Inner screw

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;
The outermost layer of the one or more intermediate layers, and a surface layer mainly composed of diamond-like carbon,
An optical component in which the surface layer contains fluorine.   The optical component according to claim 1, wherein the fluorine content of the surface layer is larger on the outer surface side than on the inner surface side.   The optical component according to claim 1, wherein the base material is formed of a sintered body containing zinc sulfide as a main component.

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