Patent Application
20150085369
This application claims the benefit of Japanese Priority Patent Application JP 2013-200327 filed Sep. 26, 2013, the entire contents of which are incorporated herein by reference.
The present technology relates to a laminated body having an anti-reflection function, an imaging element package, an imaging apparatus, and an electronic apparatus.
For a glass or a film used in a display, a camera lens, and the like, various anti-reflection technologies are used so as to suppress surface reflection. As the anti-reflection technology, a technology of forming a thin film with a lower refractive index than that of a substrate on a surface, and a technology of alternately laminating a high refractive index material and a low refractive index material are generally used.
However, the anti-reflection technology forms a thin film by using a vacuum process such as a sputtering, a vacuum deposition method, or the like, such that film-forming time increases and production efficiency is lowered. Furthermore, in the anti-reflection technology, since an interference phenomenon of light is used, reflectance depends on light wavelength or incident angle, and it is difficult to obtain a desired anti-reflection effect.
Recently, in order to solve these problems, a technology for achieving the anti-reflection performance by forming fine unevenness of which the size is equal to or less than a wavelength of light on the substrate surface has been developed, and is generally referred to as a moth-eye. The moth-eye has an advantage of obtaining the anti-reflection effect for a wider wavelength bandwidth compared to the above mentioned anti-reflection technology which uses an interference phenomenon of light and has less wavelength dependence.
Moth-eye is generally manufactured using a nano-imprint method (for example, refer to Japanese Unexamined Patent Application Publication No. 2010-156844). As the nano-imprint method, there are a thermal imprint method which plastically deforms the substrate by preparing a mold having a pattern opposite to a desired unevenness shape and heat-pressing the mold on the substrate, a thermal curable imprint method which applies a thermal curable resin (imprinting resin) to the substrate to press a mold on the substrate to be heat-cured, and a UV curable imprint method which applies a ultraviolet ray curable resin (imprinting resin) to a substrate, and irradiates the substrate with UV rays to be cured while pressing a mold on the substrate. When forming the moth-eye on an inorganic substrate such as a glass and the like, the thermal curable imprint method, and the UV curable imprint method are mainly used.
However, in the imprint method, interference fringes may occur on a surface which is imprint molded, thereby lowering visibility.
It is desirable to provide a laminated body, an imaging element package, an imaging apparatus and an electronic apparatus in which occurrence of the interference fringes is suppressed.
A laminated body according to an embodiment of the present technology includes a substrate and a structure layer which is provided on the substrate and has an anti-reflection function, in which the structure layer includes a plurality of structure bodies, and an intermediate layer which is provided between the plurality of structure bodies and the substrate, and in which the intermediate layer satisfies a following relational expression (1).
(2π/λ)·n(λ)−|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, d0 represents a thickness of the intermediate layer at a center point, and d represents a thickness of the intermediate layer at any point)
An electronic apparatus according to another embodiment of the present technology includes a substrate and a structure layer which is provided on the substrate and has an anti-reflection function, in which the structure layer includes a plurality of structure bodies, and an intermediate layer which is provided between the plurality of structure bodies and the substrate, and in which the intermediate layer satisfies a following relational expression (2) in any section.
(2π/λ)·n(λ)·|D−D0|<π (2)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, D0 represents a thickness of the intermediate layer at a center point of the section, and D represents a thickness of the intermediate layer at any point of the section)
An imaging element package according to still another embodiment of the present technology includes an imaging element, and a package which includes a light transmitting unit and accommodates the imaging element, in which the light transmitting unit includes a substrate, and a structure layer which is provided on the substrate and has an anti-reflection function, in which the structure layer includes a plurality of structure bodies, and an intermediate layer which is provided between the plurality of structure bodies and the substrate, and in which the intermediate layer satisfies a following relational expression (1).
(2π/λ)·n(λ)−|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, d0 represents a thickness of the intermediate layer at a center point, and d represents a thickness of the intermediate layer at any point (a thickness of the intermediate layer at any point in a predetermined range centered on the center point))
The laminated body or the structure layer in the laminated body is suitably applied to an optical element, an optical system, an imaging apparatus, an imaging element package, an imaging module, an optical apparatus, an electronic apparatus, and the like. As the optical element, for example, a lens, a filter, a semi-transmissive mirror, a light control element, prism, a polarizing element, a display front plate, and the like are exemplified; however, the optical element is not limited thereto. As the imaging apparatus, for example, a digital camera, a digital video camera, and the like are exemplified; however, the imaging apparatus is not limited thereto. As the optical apparatus, for example, a telescope, a microscope, an exposure apparatus, a measuring apparatus, an inspection apparatus, an analyzing apparatus, and the like are exemplified; however, the optical apparatus is not limited thereto. As the electronic apparatus, a personal computer, a mobile phone, a tablet computer, a display apparatus, and the like are exemplified; however, the electronic apparatus is not limited thereto.
As described above, it is possible to suppress occurrence of interference fringes in a transparent laminated body according to the present technology.
The present inventors have performed a keen examination so as to elucidate a reason for the occurrence of the above-mentioned interference fringes. As a result, the inventors have elucidated a reason for the occurrence of the interference fringes. That is, in a method of applying a resin to a substrate such as a glass, a film, or the like and performing imprinting, an intermediate layer made of an imprinting resin is formed between a plurality of structure bodies and the substrate. Moreover, in the above-mentioned imprint method, materials of the substrate and the imprinting resin are generally different from each other, thereby causing a difference between refractive indexes of both materials. Thus, Fresnel reflection occurs at an interface between the substrate and the intermediate layer. When such a Fresnel reflection occurs and a thickness of the intermediate layer varies, the interference fringes may occur on a molded surface.
Therefore, the present inventors have repeatedly performed a keen examination on a technology of suppressing occurrence of the interference fringes. As a result, the inventors have found out a method of making the intermediate layer which satisfies a following relational expression (1).
(2π/λ)·n(λ)−|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, d0 represents a thickness of the intermediate layer at a center point, and d represents a thickness of the intermediate layer at any point)
Embodiments of the present technology will be described in a following order.
1. First embodiment (an example of a transparent laminated body including a plurality of convex structure bodies)
2. Second embodiment (an example in which the transparent laminated body is applied to an imaging element package)
3. Third embodiment (an example in which the transparent laminated body or a structure layer is applied to a camera module)
4. Fourth embodiment (an example in which the transparent laminated body or the structure layer is applied to a digital camera)
5. Fifth embodiment (an example in which the transparent laminated body or the structure layer is applied to a digital video camera)
6. Sixth embodiment (an example in which the transparent laminated body or the structure layer is applied to an electronic apparatus)
Hereinafter, an example of a configuration of a transparent laminated body 11 will be described referring to
A size of the transparent laminated body 11 is substantially the same size as a surface (applied surface) of an application object. As the application object, for example, window materials such as an image sensor cover glass and the like, filters such as a camera ND filter and the like, lenses such as a camera lens and the like, optical elements such as a semi-transmissive mirror, a light control element, a prism, a polarizing element, a display front plate, and the like are exemplified; however, the application object is not limited thereto.
Hereinafter, the substrate 12 and the structure layer 13 which are included in the transparent laminated body 11 will be sequentially described.
The substrate 12 has transparency. A material of the substrate 12 may be a material having transparency, and may be any one of an organic material and an inorganic material. As a material of an inorganic substrate, for example, quartz, sapphire, glass, and the like are exemplified. As an organic material, it is possible to use, for example, a common high polymer material. As a common high polymer material, specifically, for example, triacetylcellullose (TAC), polyester (TPEE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polyamide (PA), aramid, polyethylene (PE), polyacrylate, polyether sulfone, polysulfone, polypropylene (PP), diacetyl cellulose, polyvinyl chloride, acrylic resin (PMMA), polycarbonate (PC), epoxy resin, urea resin, urethane resin, melamine resin, cyclo-olefin polymer (COP), cyclo-olefin copolymer, and the like are exemplified.
When using the organic material as a material of the substrate 12, an undercoat layer may be provided as surface processing so as to improve a surface energy, coating properties, slip properties, flatness, and the like of a surface of the substrate 12. As a material of the undercoat layer, for example, organoalkoxymetal compound, polyester, acrylic-modified polyester, polyurethane, and the like are exemplified. In addition, in order to obtain the same effect as providing the undercoat layer, surface processing such as corona discharge, UV irradiation processing, and the like may be performed on the surface of the substrate 12.
As a shape of the substrate 12, for example, a film shape, a plate shape, and a block shape can be exemplified; however, the shape of the substrate 12 is not limited to these shapes. Here, the film shape is defined to include a sheet shape. A thickness of the substrate 12 is, for example, about 25 μm to 500 μm. When the substrate 12 is a plastic film, the substrate 12 can be obtained by a method of, stretching the above-mentioned resin, a method of, after diluting the resin with a solvent, depositing the resin in a film shape, and drying the resin and the like. The substrate 12 may be a configuration element of a member, an apparatus, and the like which is an application object of the transparent laminated body 11.
The surface of the substrate 12 is not limited to have a flat surface, but may have an unevenness surface, a polygonal surface, a curved surface, or a combination of these shapes. As a curved surface, for example, a partial spherical surface, a partial ellipsoid surface, a partial paraboloid surface, a free curved surface, and the like are exemplified. Here, the partial spherical surface, the partial ellipsoid surface, and the partial paraboloid surface mean a portion of a spherical surface, an ellipsoid surface, and a paraboloid surface, respectively.
The structure layer 13 is an anti-reflection layer having an anti-reflection function. The structure layer 13 includes a plurality of structure bodies 14, and an intermediate layer (optical layer) 15 provided between a lower portion of the plurality of structure bodies 14 and the surface of the substrate 12.
The structure body 14 is a so-called sub-wavelength structure body. The structure body 14 has a convex shape with respect to a surface of the substrate 12. The plurality of structure bodies 14 are disposed at a pitch P of a wavelength bandwidth or less of light for a purpose of reduction of reflection. Here, the wavelength bandwidth of light for a purpose of reduction in reflection is, for example, a wavelength bandwidth of ultraviolet light, a wavelength bandwidth of visible light, or a wavelength bandwidth of infrared light. The wavelength bandwidth of ultraviolet light refers to a wavelength bandwidth of 10 nm or more and less than 350 nm, the wavelength bandwidth of visible light refers to a wavelength bandwidth of 350 nm to 850 nm, and the wavelength bandwidth of infrared light refers to a wavelength bandwidth of more than 850 nm to 1 mm.
For example, the plurality of structure bodies 14 are arranged so as to form a plurality of rows on a surface of the substrate 12. The rows may be either in a straight line shape or in a curve shape. A plurality of rows in some regions on a surface of the substrate 12 may be in a straight line shape, and a plurality of rows in the other regions may be in a curve shape. As a curve, a curve periodically or non-periodically meandering is exemplified. As such a curve, waveforms such as sine wave, triangular wave, and the like can be exemplified; however, the curve is not limited thereto.
A disposition of a plurality of structure bodies 14 on a surface of the substrate 12 may be any one of a regular disposition and an irregular disposition. As the regular disposition, a lattice-shaped disposition such as a tetragonal lattice, a quasi-tetragonal lattice, a hexagonal lattice, a quasi-hexagonal lattice, and the like are preferred.
As a specific shape of the structure body 14, for example, a cone shape, a pillar shape, a needle shape, a semi-sphere shape, a semi-ellipse shape, a polygonal shape, and the like are exemplified. However, the specific shape of the structure body is not limited to these shapes, but other shapes may be adopted. As the cone shape, for example, a cone shape whose top is pointed, a cone shape whose top is flat, and a cone shape with a convex-shaped curved surface or a concave-shaped curved surface at a top thereof are exemplified; however, the cone shape is not limited these shapes. As a cone shape with a convex-shaped curved surface at a top, a secondary curved surface shape such as a parabolic surface shape, and the like are exemplified. In addition, a conical surface of the cone shape may be curved in a concave shape or a convex shape.
The plurality of structure bodies 14 provided on the surface of the substrate 12 may all have the same size, shape, and height, and the plurality of structure bodies 14 may include those having different sizes, shapes, or heights. Furthermore, the plurality of structure bodies 14 may include structure bodies connecting lower portions with each other to be overlapped.
An intermediate layer 15 is a layer which is integrally molded with a structure body 14 at a lower portion side of the structure body 14, and configured of the same material as the structure body 14. A thickness d of the intermediate layer 15, as shown in
The intermediate layer 15 satisfies a following relational expression (1), and thereby it is possible to prevent interference fringes from occurring on the surface 11s of the transparent laminated body 11. That is, it is possible to prevent light and shade from being repeatedly changed in the surface direction of the surface of the substrate 12.
(2π/λ)·n(λ)−|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer 15 when the wavelength is λ, d0 represents a thickness of the intermediate layer 15 at a center point p0, and d represents a thickness of the intermediate layer 15 at any point p)
It is preferable that the intermediate layer 15 satisfy a following relational expression (2). This is because it is possible to further suppress occurrence of light and shade in the surface of the substrate 12.
(2π/λ)·n(λ)·|d−d0|<π/2 (2)
A thickness of the intermediate layer 15 is in a scope of preferably 10 nm to 50 μm, more preferably 30 nm to 25 μm, far more preferably 50 nm to 10 μm. If the thickness exceeds 50 μm, when forming the intermediate layer 15 by curing a resin, there is a possibility that poor adhesion occurs at an interface between the intermediate layer 15 and the substrate 12 by a curing shrinkage of the resin. Moreover, there is also a concern of a decrease in transmittance. On the other hand, if the thickness is less than 10 nm, when stress is applied to the structure body 14, the stress may not escape to the intermediate layer 15 below the structure body 14, and there is a concern of a decrease in mechanical properties of the transparent laminated body 11 due to as a broken structure body 14 and the like.
It is preferable that a maximum reflectance of the structure layer 13 itself with respect to light for a purpose of reduction in reflection be 0.21% or less. Accordingly, it is possible to suppress ripple in a spectral reflection spectrum, and to realize the transparent laminated body 11 which has an excellent anti-reflection effect. It is preferable that a maximum reflectance of the transparent laminated body 11 with respect to the light for a purpose of reduction in reflection be 1.00% or less. Here, a maximum reflectance of any one of the structure layer 13 itself and the transparent laminated body 11 also means a maximum reflectance at the surface 11s side having an anti-reflection function.
A refractive index difference Δn(=|n1−n0|) between a refractive index n0 of the substrate 12 and a refractive index n1 of the structure layer 13 is in a scope of preferably 0.3 or less, more preferably 0.2 or less, far more preferably 0.1 or less. When the refractive index difference Δn is 0.3 or less, a good anti-reflection property is obtained.
Next, an example of a method of manufacturing the transparent laminated body 11 according to a first embodiment of the present technology will be described referring to
First, as shown in
Next, as shown in
Next, the resist layer 23 is developed by, for example, dropping a developing solution on the resist layer 23 while rotating the master 21. Thus, as shown in
Next, with a pattern (resist pattern) of the resist layer 23 formed on the master 21 as a mask, a surface of the master 21 is etched. Accordingly, as shown in
Thus, the master 21 which is targeted is obtained.
As the master 21, it is possible to use a mold (hard mold) configured of, for example, a glass, silicon, nickel, or the like. By thermal imprint, UV imprint, or the like, using such a hard mold, a replica is made by transferring a shape to a type of a resin material, a film, or the like, and the replica may be used as a mold (soft mold).
Flatness, thickness accuracy, and the like of these molds are preferably adjusted so that the intermediate layer 15 satisfying the above-mentioned relational expression (1) may be formed.
Next, shape transfer to a resin material is performed by a nano-imprint method. As a press device used in imprint, for example, a press device which includes a metal plate as a lower plate and includes a metal plate (in the case of thermal curing imprint method), or a quartz glass plate (in the case of UV curing imprint method) as an upper plate is used. In the press device having such a configuration, in-plane accuracy, parallelism, and in-plane pressure distribution of a plate is preferably adjusted so that the intermediate layer 15 satisfies the above-mentioned relational expression (1).
Specifically, as shown in
Alternatively, after bringing the master 21 and the transfer material 24 applied onto the substrate 12 in close contact with each other, the transfer material 24 is cured by heating the transfer material 24 using a heat source such as a heater and the like, and the substrate 12 which is integrated with the cured transfer material 24 is peeled off. Accordingly, as shown in
The energy ray source 25 may be a source which is capable of emitting energy rays such as electronic rays, ultraviolet rays, infrared rays, laser rays, visible rays, ionizing radiation (X-rays, α-rays, β-rays, γ-rays, and the like), a microwave, high-frequency rays or the like; however, the energy ray source is not particularly limited thereto.
As the transfer material 24, it is preferable to use an energy ray curable resin composition or a thermosetting resin, and these may be combined to be used. As an energy ray curable resin composition, it is preferable to use a ultraviolet ray curable resin composition, and for example, it is possible to use an acrylic resin material, an epoxy-based resin material, and the like. As the thermosetting resin, it is possible to use inorganic materials such as glass and the like. The transfer material 24 may include a filler, a functional additives, or the like when necessary.
A ultraviolet ray curable resin composition includes, for example, acrylate and an initiator. The ultraviolet ray curable resin composition includes a mono-functional monomer, a bi-functional monomer, a poly-functional monomer, and the like. Specifically, the ultraviolet ray curable resin composition is made by a single material alone or a mixture of two or more materials shown below.
As the mono-functional monomer, for example, carboxylic acids (acrylic acid), hydroxy acids (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxy butyl acrylate), alkyl, alicyclic acids (isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate), other functional monomers (2-methoxyethyl acrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethylcarbitol acrylate, phenoxy ethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl acrylamide, N,N-dimethylacrylamide, acryloylmorpholine, N-isopropyl acrylamide, N,N-diethyl acrylamide, N-vinyl pyrrolidone, 2-(perfluorooctyl)ethyl acrylate, 3-perfluoro-hexyl-2-hydroxypropyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-(perfluorodecyl)ethyl acrylate, 2-(perfluoro-3-methylbutyl)ethyl acrylate), 2,4,6-tribromophenol acrylate, 2,4,6-tribromophenol methacrylate, 2-(2,4,6-tribromo-phenoxy)ethyl acrylate), 2-ethylhexyl acrylate, and the like can be exemplified.
As the bi-functional monomer, for example, tri(propylene glycol)diacrylate, trimethylolpropane diallyl ether, urethane acrylate, and the like can be exemplified.
As the poly-functional monomer, for example, trimethylol propane triacrylate, dipentaerythritol penta and hexacrylate, ditrimethylolpropane tetraacrylate, and the like can be exemplified.
As the initiator, for example, 2,2-dimethoxy-1,2-diphenyl-ethane-1-on, 1-hydroxycyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-phenylpropane-1-on, and the like can be exemplified.
As the filler, for example, it is possible to use any one of inorganic fine particles and organic fine particles. As the inorganic fine particles, for example, metal oxide fine particles such as SiO2, TiO2, ZrO2, SnO2, Al2O3, and the like can be exemplified.
As the functional additives, for example, a leveling agent, a surface conditioning agent, anti-form, and the like can be exemplified. A method of molding the substrate 12 is not particularly limited, and the substrate 12 may be injection molded body, an extrusion-molded body, and a cast molded body. Surface processing such as corona processing and the like may be performed on the substrate surface when necessary.
As described above, the transparent laminated body 11 of interest may be obtained.
In the transparent laminated body 11 according to a first embodiment, the intermediate layer 15 satisfies the above-mentioned relational expression (1), such that it is possible to suppress occurrence of interference fringes. Thus, when applying the transparent laminated body 11 to a display device or a camera, it is possible to realize a display with excellent visibility, or a camera without unexpected reflection caused by stray light.
When a maximum reflectance of the structure layer 13 itself with respect to the light for a purpose of reduction in reflection is 0.2% or less, ripples in a spectral reflection spectrum are suppressed. Therefore, the occurrence of interference fringes is suppressed, and it is possible to realize the transparent laminated body 11 with an excellent anti-reflection effect.
As shown in
When the structure body 14 has a pointed top or a planar top, it is preferable that a diameter Dbottom of a bottom of the structure body 14 and a pitch P of the structure body 14 satisfy a relationship of 1.2>Dbottom/P>1, and a diameter Dtop of a top of the structure body 14 and the diameter Dbottom of the bottom of the structure body 14 satisfy a relationship of 0≦Dtop/Dbottom≦1/10. As a pointed top shape, for example, a convex curved surface, a needle shape, and the like are exemplified; however, the pointed top shape is not limited thereto.
As shown in
In the first embodiment, a case where the structure body 14 has a convex shape with respect to the surface of the substrate 12 is described as an example (refer to
In the first embodiment, a case where a size of the transparent laminated body 11 is substantially the same as a size of a surface (applied surface) of the application object is described as an example; however, the transparent laminated body 11 may be larger than the surface of the application object. For example, the transparent laminated body 11 may be a raw film. In this case, the transparent laminated body 11 is cut into a surface size of an application object such as an image sensor cover glass, an ND filter, or the like to be used.
In
As described above, when cutting a portion of the section 11R to be used, the intermediate layer 15 satisfies a following relational expression (2). By satisfying the relational expression (2), when applying a cut section 11R to the surface of the application object, it is possible to prevent interference fringes from occurring on an applied surface of the application object.
(2π/λ)·n(λ)·|D−D0|<π (2)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer 15 when the wavelength is λ, D0 represents a thickness of the intermediate layer 15 at a center point P0 of the section 11R, and D represents a thickness of the intermediate layer 15 at any point P of the section 11R)
As shown in
A transparent laminated body 11a includes a cover glass (cover body) 12a which is a substrate, and a structure layer 13a provided on a surface of the cover glass 12a. The structure layer 13a is the same as the structure layer 13 in the first embodiment or the modification examples of the first embodiment. The cover glass 12a has a front surface (first surface) 12s1 on which light from a subject is incident, and a rear surface (second surface) 12s2 from which light incident from the front surface is emitted. The structure layer 13a is provided at one side of the front surface 12S1 and the rear surface 12s2, and it is preferable to provide the structure layer on both sides of these in terms of improving an anti-reflection property and a transmitting property. In
As the imaging element 122, for example, a Charge Coupled Device (CCD) image sensor element, a Complementary Metal Oxide Semiconductor (COMS) image sensor element, or the like is used.
In the element package 114 according to the second embodiment, the structure layer 13a is provided on the surface of the cover glass 12a, such that it is possible to give an anti-reflection property on the surface of the cover glass 12a without causing occurrence of the interference fringes.
As shown in
As shown in
At a predetermined position on a surface of the circuit substrate 136, the imaging element 134 is mounted. In order to accommodate the imaging element 134, a housing 135 is fixed to a surface of the circuit substrate 136. In the housing 135, the lens 132 and the IR cut lens 133 are accommodated. The lens 132 and the IR cut lens 133 are provided at predetermined intervals in this order toward the imaging element 134 from a subject. Light from the subject is collected by the lens 132, and is image-formed on an imaging surface of the imaging element 134 through the IR cut lens 133. The transparent laminated body 11 or the structure layer 13 according to the first embodiment or modification examples of the first embodiment are included on a surface of the lens 132 and the IR cut lens 133.
Here, a surface means at least one of the front surface on which light from a subject is incident and the rear surface from which the light incident from the front surface is emitted.
In a fourth embodiment, an example that the transparent laminated body 11 according to the above-mentioned first embodiment or the structure layer 13 of the transparent laminated body is applied to an imaging apparatus will be described.
The imaging optical system 103 includes a lens 111, a light amount adjusting device 112, a semi-transmissive mirror 113, an element package 114a, a auto-focus sensor 115. The lens 111, the light amount adjusting device 112, and the semi-transmissive mirror 113 are provided in this order toward the element package 114a from a tip of the lens barrel 102. At least one type selected from a group made of the lens 111, the light amount adjusting device 112, the semi-transmissive mirror 113, and the element package 114a is given an anti-reflection function. The auto-focus sensor 115 is provided at a position at which light L reflected by the semi-transmissive mirror 113 can be received. The imaging apparatus 100 may further include a filter 116 when necessary. When the imaging apparatus 100 includes the filter 116, the anti-reflection function may be given to the filter 116. Hereinafter, each configuration element and the anti-reflection function will be sequentially described.
The lens 111 collects light L from a subject toward the element package 114a.
The light amount adjusting device 112 is a diaphragm device which adjusts a size of an opening for a diaphragm about an optical axis of the imaging optical system 103. The light amount adjusting device 112 includes, for example, a pair of diaphragm blades, and an ND filter to reduce an amount of transmitted light. As a driving method of the light amount adjusting device 112, it is possible to use, for example, a method of driving the pair of diaphragm blades and the ND filter by one actuator, and a method of driving the pair of diaphragm blades and the ND filter by respective independent two actuators; however, the driving method is not particularly limited to these methods. As the ND filter, it is possible to use a filter with a single transmittance or concentration, or a filter in which transmittance or concentration changes in a gradient shape. Moreover, the number of the ND filters is not limited to one, and a plurality of ND filters may be laminated to be used.
The semi-transmissive mirror 113 is a mirror which allows a portion of incident light to transmit through, and reflects the rest. Specifically, while reflecting a portion of the light L collected by the lens 111 toward the auto-focus sensor 115, the semi-transmissive mirror 113 allows the rest of the light L to be transmitted through toward the element package 114a. As a shape of the semi-transmissive mirror 113, for example, a sheet shape and a plate shape can be exemplified; however, the shape of the semi-transmissive mirror 113 is not particularly limited to these shapes. Here, a film is defined to be included in a sheet.
An element package 114a receives light transmitted through the semi-transmissive mirror 113, converts the received light into an electrical signal, and outputs the signal to a signal processing circuit (not illustrated).
The auto-focus sensor 115 receives light reflected by the semi-transmissive mirror 113, converts the received light into an electrical signal, and outputs the signal to a control circuit (not illustrated).
The filter 116 is provided at the tip of the lens barrel 102, or in the imaging optical system 103. In
As the filter 116, a filter generally provided at the tip of the lens barrel 102 or in the imaging optical system 103 is used; however, the filter is not particularly limited thereto. For example, a polarization (PL) filter, a sharp cut (SC) filter, a filter for color emphasis and effects, a dimming (ND) filter, a color temperature conversion (LB) filter, a color correction (CC) filter, a white balance acquisition filter, a lens protection filter, and the like are exemplified.
In the imaging apparatus 100, light from a subject transmits through a plurality of optical elements (that is, the lens 111, the light amount adjusting device 112, the semi-transmissive mirror 113, and a cover glass of the element package 114a) until reaching an imaging element in the element package 114a from the tip of the lens barrel 102. In the following, the optical element through which the light L transmits from a subject transmits from being included in an imaging apparatus 100 until reaching an imaging element is referred to as “transmission type optical element”. When the imaging apparatus 100 further includes the filter 116, the filter 116 is also regarded as a type of the transmission type optical element.
On a surface of at least one transmission type optical element among the plurality of these transmission type optical elements, the transparent laminated body 11 according to the above-mentioned first embodiment or the structure layer 13 of the transparent laminated body is provided. Alternatively, the transparent laminated body 11 according to modification examples of the above-mentioned first embodiment or the structure layer 13 of the transparent laminated body may be provided. Here, the surface of the transmission type optical element means an incident surface on which light L from a subject is incident or an emitting surface from which incident light from the incident surface is emitted. Specifically, for example, as the element package 114a, it is possible to use the element package 114 according to the above-mentioned second embodiment or modification examples of the second embodiment.
In the above-mentioned fourth embodiment, a case of applying the present technology to a digital camera (digital still camera) as an imaging apparatus is described as an example; however, application examples of the present technology are not limited thereto. In a fifth embodiment of the present technology, an example that the present technology is applied to a digital video camera will be described.
The first lens group L1 and the third lens group L3 are for a fixed lens. The second lens group L2 is for a zoom lens. The fourth lens group is for a focusing lens.
The element package 202 converts incident light into an electrical signal, and supplies the signal to a signal processing unit which is not illustrated.
The low pass filter 203 is provided on, for example, a front surface of the element package 202, that is, a light incident surface of the cover glass. The low pass filter 203 is intended to suppress a false signal (moire) occurring when photographing a striped image and the like which is close to a pixel pitch, and is configured from an artificial crystal.
For example, the filter 204 is intended to cut an infrared range of light incident onto the element package 202, and to suppress a spectral floating in a near-infrared range (630 nm to 700 nm), and to make a light intensity in a visible range band (400 nm to 700 nm) uniform. The filter 204 is configured to have, for example, the infrared light cut filter (hereinafter, IR cut filter) 204a, and a IR cut coating layer 204b which is formed by laminating IR cut coating on the IR cut filter 204a. Here, for example, the IR cut coating layer 204b is formed on at least one of a surface of a subject side of the IR cut filter 204a and a surface of the element package 202 side of the IR cut filter 204a. In
The motor 205 moves the fourth lens group L4 based on a control signal supplied from a control unit which is not illustrated. The iris blade 206 is intended to adjust an amount of light incident onto the element package 202, and is driven by a motor which is not illustrated.
The electric light control element 207 is intended to adjust an amount of light incident onto the element package 202. The electric light control element 207 is an electric light control element which is made of a liquid crystal including at least dye-based pigment, and an electric light control element which is made of a dichroic GH liquid crystal.
In the imaging apparatus 201, light from a subject transmits through a plurality of optical elements (the first lens group L1, the second lens group L2, the electric light control element 207, the third lens group L3, the fourth lens group L4, the filter 204, and the cover glass with the low pass filter 203) until reaching an imaging element in the element package 202. Hereinafter, an optical element through which the light from a subject transmits until reaching an imaging element is referred to as “transmission type optical element”. The transparent laminated body 11 or the structure layer 13 of the transparent laminated body according to the above-mentioned first embodiment is provided on a surface of at least one transmission type optical element among the plurality of these transmission type optical elements. Alternatively, the transparent laminated body 11 or the structure layer 13 of the transparent laminated body according to modification examples of the above-mentioned first embodiment may be provided. Specifically, for example, as the element package 202, the element package 114 according to the above-mentioned second embodiment or modification example of the second embodiment can be used.
An electronic apparatus according to a sixth embodiment includes a camera module 131 according to the third embodiment. Hereinafter, an example of an electronic apparatus according to a seventh embodiment of the technology will be described.
Referring to
The display 303 includes a housing 321, and a display element 322 and a camera module 131 which are accommodated in the housing 321. The transparent laminated body 11 or the structure layer 13 of the transparent laminated body according to the first embodiment may be included in a display surface of the display element 322. Alternatively, the transparent laminated body 11 or the structure layer 13 of the transparent laminated body according to modification examples of the above-mentioned first embodiment may be included.
When a front surface plate is provided on a front surface of the display 303, the transparent laminated body 11 or the structure layer 13 of the transparent laminated body according to the first embodiment may be provided on a surface of the front surface plate. Alternatively, the transparent laminated body 11 or the structure layer 13 of the transparent laminated body according to modification examples of the first embodiment may be included. Here, the surface means at least one of a front surface on which external light is incident and a rear surface from which external light incident from the front surface is emitted.
Referring to
Referring to
Hereinafter, the present technology will be described in detail by examples; however, the present technology is not limited to only these examples.
Diameter Dbottom of a bottom, diameter Dtop of a top, height H, and pitch P
In the present example, a diameter Dbottom of a bottom of a structure body, a diameter Dtop of a top, height H, and pitch P are measured as follows. First, a transparent laminated body is cut so as to include a top of a structure body, and a cross-section of the transparent laminated body is photographed using a transmission type electronic microscope (TEM). Next, from a photographed TEM picture, a diameter Dbottom of a bottom of a structure body, a diameter Dtop of a top, height H, and pitch P are determined.
A Thickness d0 of an Intermediate Layer at a Center Point
In the present example, a thickness d0 of an intermediate layer at a center point on a surface of the transparent laminated body is measured in a following manner. First, a transparent laminated body is cut so as to include a center point on the surface and a top of the structure body, and the cross-section is photographed using the TEM. Next, from the photographed TEM picture, a thickness d0 of an intermediate layer at a substantially center point on the surface of the transparent laminated body is determined. Here, a distance from the surface of a glass substrate to a deepest position of a valley portion between adjacent structure bodies is defined as a thickness of the intermediate layer.
Maximum Displacement Thickness dΔmax of an Intermediate Layer
In the present example, on a basis of the thickness d0 of an intermediate layer at a center point on the surface of the transparent laminated body, a thickness d (that is, a maximum displacement thickness dΔmax of an intermediate layer) of an intermediate layer at a position where an amount of change in the thickness d becomes maximum is determined. First, the transparent laminated body is cut so as to include a center point on the surface and a top of the structure body, and a cross-section of the transparent laminated body is photographed using the TEM. Next, a thickness d of an intermediate layer is determined from the photographed TEM picture. Here, a distance from the surface of a glass substrate to a deepest position of a valley portion between adjacent structure bodies is defined as a thickness of the intermediate layer. Next, the transparent laminated body is cut so as to include a center point on the surface and a top of the structure body in a direction orthogonal to the cutting direction, and a thickness d of the intermediate layer is determined in the same manner as described above. Next, from the thicknesses d of the intermediate layer in two directions determined as described above, a thickness d of an intermediate layer at a position where an amount of change in the thickness d becomes maximum is determined on a basis of a thickness d0 at a center point, and the thickness d becomes a maximum displacement thickness dΔmax of the intermediate layer.
Refractive Index n0
In the example, a refractive index n0 of a glass substrate is measured using an Abbe refractive index meter. A measurement wavelength is 589 nm.
Refractive Index n1
A refractive index of a UV curing resin (that is, a refractive index of an intermediate layer) n1 is measured as follows. First, a UV curing resin used in a UV nano-imprint transfer is irradiated with 2000 mj/cm2 of UV light of Hg lamp to be cured, and thereby manufacturing a sample for measurement. Next, by measuring a refractive index of the manufactured sample using the Abbe refractive index meter, the refractive index is set to be a refractive index n1 of the UV curing resin. A measurement wavelength is 589 nm.
First, an 8 inch silicon wafer is spin-coated with photo resist. Next, in a stepper (reduction projection type exposure apparatus), an exposure pattern of a hexagonal lattice shape is formed. Next, after developing a photo-resist layer and forming a plurality of photo resist patterns on a silicon wafer, a plurality of anti-reflection structure bodies are formed by performing an etching process using the photo-resist pattern in a mask. Thereafter, the photo-resist pattern is removed to make a mold which has a plurality of anti-reflection structure bodies (sub-wavelength structure body) on a surface. Exposure conditions and etching conditions are adjusted so that a plurality of structure bodies having a diameter Dbottom of a bottom: 255 nm, a diameter Dtop of a top: 10 nm, a height H: 300 nm, and a pitch P: 250 nm are molded in a UV nano-imprint transfer to be described below.
Next, after performing fluorine processing on a surface of the mold obtained in the above-mentioned manner, a transparent laminated body is made in a following manner by the UV nano-imprint transfer using the mold. First, after preparing a glass substrate having a refractive index n0: 1.64, and spin-coating the glass substrate with an acrylic UV curing resin having a refractive index n1: 1.48, and a molded surface of a mold is pressed against a coated UV curing resin. Then, after irradiating the resin with 2000 mJ/cm2 of UV light of Hg lamp to be cured, the mold is peeled off from the glass substrate. Accordingly, a transparent laminated body which has an intermediate layer (refractive index: 1.48) between the plurality of structure bodies arranged in a hexagonal lattice shape and the glass substrate is obtained. A thickness d0 of the intermediate layer at a center point is set to be 520 nm and a maximum displacement thickness dΔmax is set to be 553 nm by a pressing condition adjustment of a mold.
By an adjustment of the exposure conditions and the etching conditions, diameters Dbottom of bottoms of a plurality of structure bodies obtained by the UV nano-imprint transfer is set to be 200 nm. Moreover, by a pressing condition adjustment of a mold, a thickness d0 of the intermediate layer at a center point is 510 nm, a maximum displacement thickness dΔmax is 490 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
By an adjustment of the exposure conditions and the etching conditions, diameters Dtop of tops of a plurality of structure bodies obtained by the UV nano-imprint transfer are 25 nm. In addition, by the pressing condition adjustment of a mold, a thickness d0 of the intermediate layer at a center point is 505 nm, and the maximum displacement thickness dΔmax is 490 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
By an adjustment of the exposure conditions and the etching conditions, diameters Dtop of tops of a plurality of structure bodies obtained by the UV nano-imprint transfer are 30 nm. In addition, by a pressing condition adjustment of a mold, a thickness d0 of an intermediate layer at a center point is 500 nm, and a maximum displacement thickness dΔmax is 528 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
Instead of a glass substrate having refractive index n0: 1.64, a glass substrate having refractive index n0: 1.76 is used. In addition, by a pressing condition adjustment of a mold, a thickness d0 of the intermediate layer at a center point is 530 nm, and a maximum displacement thickness dΔmax is 506 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
Instead of the glass substrate having refractive index n0: 1.64, a glass substrate having refractive index n0: 1.80 is used. In addition, by a pressing condition adjustment of a mold, the thickness d0 of the intermediate layer at a center point is 540 nm, and the maximum displacement thickness dΔmax is 520 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
Instead of an acrylic UV curing resin having refractive index n0:1.48, an acrylic UV curing resin having refractive index n0:1.60 is used. In addition, by a pressing condition adjustment of a mold, the thickness d0 of the intermediate layer at a center point is 550 nm, and the maximum displacement thickness dΔmax is 520 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 5.
By a pressing condition adjustment of a mold, the thickness d0 of an intermediate layer at a center point is 490 nm, and the maximum displacement thickness dΔmax is 120 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
By a pressing condition adjustment of a mold, the thickness d0 of an intermediate layer at a center point is 510 nm, and the maximum displacement thickness dΔmax is 1200 nm. Except for this, a transparent laminated body is obtained in the same manner as Example 1.
The following evaluation is made for the transparent laminated body obtained as described above.
First, black tape is bonded on a back surface of the transparent laminated body. Next, light is incident from a surface which is a side opposite to a side to which black tape is bonded, and reflection spectrum (wavelength bandwidth 350 nm to 850 nm) of an optical film is measured by using an evaluation device (V-550) of Nippon Bunko Co. Next, from this reflection spectrum, a maximum reflectance having a wavelength bandwidth of 350 nm to 850 nm is determined.
As described below, by manufacturing a sample of a structure layer itself, a maximum reflectance of the structure layer itself of the transparent laminated body is evaluated in a pseudo manner. First, acrylic UV curing resins having refractive indexes n: 1.48 and 1.73 used in each example and comparative example are prepared. Next, after dropping these resins on a molded surface of a mold used in each example and comparative example, pressing and curing these resins, a mold is peeled off from the cured resin. As a result, a sample of the structure layer itself is obtained. Next, in the same manner as in the evaluation of “the above-mentioned maximum reflectance of the transparent laminated body”, the reflectance spectrum is measured and maximum reflectance having a wavelength bandwidth of 350 nm to 850 nm is obtained from the reflectance spectrum.
A numerical value is obtained by substituting a thickness d0 of the intermediate layer in each example and comparative example, and a maximum displacement thickness dΔmax in the following relational expression. A value of a wavelength λ is set to be a minimum wavelength 350 nm in the wavelength bandwidth 350 nm to 850 nm. In addition, a refractive index n is set to a refractive index of the intermediate layer at a wavelength 589 nm or a refractive index n1.
(2π/λ)·n·|dΔmax−d0|
First, a black acrylic plate is bonded to a back surface of the transparent laminated body. Next, using 3-wavelength fluorescent lamp in a dark room, light is allowed to be incident at an incident angle of 30 degrees from a surface which is a side opposite to the side to which the black acrylic plate is bonded, and thereby regular reflection interference fringes are visually observed and are evaluated by a following reference.
O: Interference fringes are observed.
X: Interference fringes are not observed.
First, in the same manner as the evaluation of the above-mentioned “maximum reflectance of the transparent laminated body”, the reflectance spectrum is measured. Next, from the reflectance spectrum, ripples are measured by the following reference.
O: Maximum reflectance ≦1%
X: Maximum reflectance >1%
Tables 1 and 2 show a configuration and evaluation result of the transparent laminated body of the Examples 1 to 7, and the Comparative Examples 1 and 2.
The following can be seen from the tables 1 and 2.
In the Examples 1 to 7, the intermediate layer satisfies a relation of (2π/λ)·n·|dΔmax−d0|<π, and thereby occurrence of the interference fringes is suppressed. On the other hand, in the Comparative Examples 1 and 2, the intermediate layer does not satisfy a relationship of (2π/λ)·n·|dΔmax−d0|<π, and thereby the interference fringes occur.
In the Examples 1, 3, 5, and 7, a maximum reflectance Rb of a shape single layer is 0.21% or less, a refractive index difference Δn between a refractive n0 of the glass substrate and a refractive index n1 of the structure layer is 0.3 or less, such that ripples are suppressed and a maximum reflectance Ra of the transparent laminated body can be 1.0% or less. On the other hand, in the Examples 2 and 4, the refractive index difference Δn is 0.3 or less. However, since the maximum reflectance Rb of the structure layer itself exceeds 0.2%, ripples are large and the maximum reflectance Ra of the transparent laminated body exceeds 1.0. Moreover, the maximum reflectance Rb of the transparent laminated body in Example 6 is 0.2% or less. However, since the refractive index difference Δn exceeds 0.3, ripples are large, and the maximum reflectance Ra of the transparent laminated body exceeds 1.0.
In the Examples 1, 3, 5, and 7, since a diameter Dbottom of a bottom of the structure body and a pitch P of the structure body satisfy a relationship of Dbottom/P>1 (that is, adjacent structure bodies overlap with each other), and a diameter Dtop of a top of the structure body and a diameter Dbottom of a bottom of the structure body satisfy a relationship of Dtop/Dbottom≦1/10, a maximum reflectance Rb of the structure layer itself can be 0.2% or less. On the other hand, in Example 2, since a pitch P of the structure body and a diameter Dbottom of a bottom of the structure body fail to satisfy a relationship of 1.2>Dbottom/P>1, a maximum reflectance Rb of the structure layer itself exceeds 0.2%. In addition, in Example 4, since a diameter Dtop of a top of the structure body fails to satisfy a relationship of 1/10 or less of the diameter Dbottom of a bottom of the structure body, the maximum reflectance Rb of the structure layer itself exceeds 0.2%.
Accordingly, the intermediate layer satisfies a relational expression (1) below, and thereby it is possible to suppress occurrence of the interference fringes.
(2π/λ)·n(λ)·|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, d0 represents a thickness of the intermediate layer at a center point, d represents a thickness of the intermediate layer at any point)
In addition, in order to suppress ripples, it is preferable that a maximum reflectance Rb of the shape single layer be 0.21% or less, and the refractive index difference Δn between a refractive index n0 of the glass substrate and a refractive index n1 of the structure layer be 0.3 or less.
In addition, in order to set a maximum reflectance Rb of the shape single layer to be 0.21% or less, it is preferable that a diameter Dbottom of a bottom of the structure body and a pitch P of the structure body satisfy a relationship of 1.2>Dbottom/P>1, and a diameter Dtop of a top of the structure body and the diameter Dbottom of a bottom of the structure body satisfy a relationship of Dtop/Dbottom≦10.
A spectrum of the transparent laminated body of the following configuration is determined by simulation. The results are shown in
Refractive index n0 of the substrate: 1.64
Refractive index n1 of the structure layer: 1.49
Reflectance of the structure layer itself: 0.5%
Fresnel reflectance between the structure layer and the substrate: 0.23%
A spectrum of the transparent laminated body of the following configuration is determined by simulation. The results are shown in
Refractive index n0 of the substrate: 1.64
Refractive index n1 of the structure layer: 1.49
Reflectance of the structure layer itself: 0.1%
Fresnel reflectance between the structure layer and the substrate: 0.23%
The following can be seen from
In Reference Example 1, since a reflectance of the structure layer itself exceeds 0.2%, ripples are large, and a maximum reflectance of the transparent laminated body exceeds 1.0.
On the other hand, in Reference Example 2, since a reflectance of the structure layer itself is 0.2% or less, ripples are suppressed and a maximum reflectance of the transparent laminated body is 1.0 or less.
As described above, embodiments of the present technology are described in detail. However, the present technology is not limited to the above-mentioned embodiment and various modifications based on the technical concepts of the present technology can be made.
For example, a configuration, a method, a process, a shape, a material, and a number, and the like exemplified in the above-mentioned embodiments are no more than exemplifications, and a different configuration, method, process, shape, material, number, and the like may be used when necessary.
Moreover, a configuration, a method, a process, a shape, a material, a number, and the like of the above-mentioned embodiments can be combined with each other without departing from the spirit of the present technology.
In addition, the present technology can adopt a following configuration.
(1) A laminated body includes: a substrate; and a structure layer which is provided on the substrate and has an anti-reflection function, in which the structure layer includes a plurality of structure bodies, and an intermediate layer which is provided between the plurality of structure bodies and the substrate, and in which the intermediate layer satisfies a following relational expression (1).
(2π/λ)·n(λ)·|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer describe above when the wavelength is λ, d0 represents a thickness of the intermediate layer at a center point, and d represents a thickness of the intermediate layer at any point)
(2) The laminated body according to (1), in which a maximum value of reflectance of the structure layer itself with respect to light for a purpose of reduction of reflection is 0.21% or less, a maximum value of reflectance of the laminated body of the substrate and the structure layer with respect to the light for a purpose of reduction of reflection is 1.00% or less.
(3) The laminated body according to (1) or (2), in which a diameter Dbottom of a bottom surface of the structure body and a pitch P of the structure body satisfy a relationship of 1.2>Dbottom/P>1, and a diameter Dtop of a top portion of the structure body and the diameter Dbottom of a bottom surface of the structure body satisfy a relationship of Dtop/Dbottom≦1/10.
(4) The laminated body according to any one of (1) to (3), in which a wavelength range of the light is 350 nm to 850 nm.
(5) The laminated body according to any one of (1) to (4), in which a thickness of the intermediate layer changes in a surface direction of the substrate surface.
(6) The laminated body according to any one of (1) to (5), in which a refractive index difference Δn(=|n1−n0|) between a refractive index n0 of the substrate and a refractive index n1 of the structure layer is 0.3 or less.
(7) The laminated body according to any one of (1) to (6), in which the plurality of structure bodies and the intermediate layer are configured of the same material.
(8) The laminated body according to any one of (1) to (7), in which the structure body has a concave or convex shape with respect to a surface of the intermediate layer.
(9) An imaging apparatus including the laminated body according to any one of (1) to (8).
(10) An electronic apparatus including the laminated body according to any one of (1) to (8).
(11) A laminated body includes: a substrate; and a structure layer which is provided on the substrate and has an anti-reflection function, in which the structure layer includes a plurality of structure bodies, and an intermediate layer which is provided between the plurality of structure bodies and the substrate, and in which the intermediate layer satisfies a following relational expression (1) in any section.
(2π/λ)·n(λ)·|D−D0|<π (2)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, D0 represents a thickness of the intermediate layer at a center point of the section, and D represents a thickness of the intermediate layer at any point of the section)
(12) An imaging element package includes: an imaging element; and a package which includes a light transmitting unit and accommodates the imaging element, in which the light transmitting unit includes a substrate, and a structure layer which is provided on the substrate and has an anti-reflection function, in which the structure layer includes a plurality of structure bodies, and an intermediate layer which is provided between the plurality of structure bodies and the substrate, and in which the intermediate layer satisfies a following relational expression (1).
(2π/λ)·n(λ)−|d−d0|<π (1)
(where, λ represents a wavelength of light for a purpose of reduction of reflection, n(λ) represents a refractive index of the intermediate layer when the wavelength is λ, d0 represents a thickness of the intermediate layer at a center point, and d represents a thickness of the intermediate layer at any point (a thickness of the intermediate layer at any point in a predetermined range centered on the center point))
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-200327 | Sep 2013 | JP | national |
