JP4978106B2 - Imaging element cover and imaging apparatus - Google Patents

Description

  The present invention relates to a solid-state image sensor cover and an imaging apparatus used for a digital still camera, a digital video camera, and the like.

An imaging device is used for a digital still camera, a digital video camera, and the like. These portable digital devices are becoming smaller and cheaper. Accordingly, there is a demand for downsizing, low profile, and low price of the imaging apparatus.
The imaging apparatus includes a plurality of components, and includes a solid-state imaging device, a package for protecting the solid-state imaging device from the external environment, a solid-state imaging device cover for sealing the package, and the like (see Patent Document 1).
In addition, an optical low-pass filter that suppresses a spatial high-frequency component included in a captured image has become necessary due to an improvement in the element density of the solid-state imaging device.
There is known a configuration in which a diffraction grating as an optical low-pass filter is incorporated in an imaging device and the number of parts is reduced as a whole digital device (see Patent Document 2 and Patent Document 3).

JP-A-9-69618 (Page 4, FIG. 3) Japanese Patent No. 2968357 (pages 3 and 4, FIG. 6) Japanese Patent Laid-Open No. 5-273501 (2nd page, FIG. 2)

Glass is used for the solid-state image sensor cover that seals the package. As the glass, borosilicate glass, soda glass or the like is used. In recent years, α-rays are generated from a small amount of heavy metal contained in these glasses, causing a problem of causing damage to the solid-state imaging device.
An object of the present invention is to obtain a solid-state imaging device cover and an imaging apparatus provided with an optical low-pass filter that prevents damage to the solid-state imaging device due to α rays while corresponding to downsizing, low profile, and low price. is there.

An imaging element cover of the present invention is a that IMAGING element cover resign sealed packages IMAGING element is housed, pre-Symbol IMAGING element cover is a Z-cut quartz crystal plate and the Z-cut quartz plate characterized in that it comprises an optical low-pass filter provided on the transmission surface of the light.

According to the present invention, as that abolish sealing IMAGING element cover the package is provided with the Z-cut quartz plate of impurities less single crystal such as heavy metals, into α line generation is least for an imaging element IMAGING element cover which prevents damage is obtained.

In the present invention, the optical low-pass filter is preferably a birefringent plate.
In the present invention, in addition to the above-described effect, the birefringent plate constitutes a two-point separation optical low-pass filter. Therefore, the number of parts is small, the structure is simple, and the manufacture is facilitated. Accordingly, miniaturization of an imaging device cover, it is possible to lower profile, and cost reduction.

In the present invention, the optical low-pass filter includes a horizontal direction separation birefringence plate and a vertical direction separation birefringence plate, and is ¼ between the horizontal direction separation birefringence plate and the vertical direction separation birefringence plate. A wave plate is preferably arranged.
In the present invention, in addition to the effects described above, the two since the optical low-pass filter of the four-point separated by the birefringent plate and a quarter-wave plate is configured, an imaging element cover more spatial high-frequency component is suppressed Is obtained.

In the present invention, the optical low-pass filter includes a first diffraction element in which a first refractive index material and a second refractive index material are periodically and alternately arranged on a light transmission surface of the Z-cut quartz plate. A lattice is desirable .
In the present invention, the optical low-pass filter has a ratio W / P of a width W of the first refractive index material and a period P of the first diffraction grating of 0.5, and the first refraction filter. the height from the surface of the Z-cut quartz plate rate material and d _L, wherein the height from the surface of the Z-cut quartz plate of the second refractive index material and d _H, wherein with respect to the wavelength lambda ₁ of the light The refractive index of the first refractive index material is n _L1 , the refractive index of the second refractive index material with respect to the light with the wavelength λ ₁ is n _H1, and the refractive index of the first refractive index material with respect to the light with the wavelength λ ₂ The refractive index is n _L2 , the refractive index of the second refractive index material with respect to the light with the wavelength λ ₂ is n _H2, and the phase modulation amount Γ ₁ of the first diffraction grating with respect to the light with the wavelength λ ₁ , when the phase modulation amount gamma ₂ of the first diffraction grating with respect to the wavelength lambda ₂ of the light, the following formula ( ) It is desirable to satisfy to (5).
Γ ₁ = {(n _H1 −n _L1 ) × d _H + (1−n _L1 ) × (d _L −d _H )} / λ ₁ (3)
Γ ₂ = {(n _H2 −n _L2 ) × d _H + (1−n _L2 ) × (d _L −d _H )} / λ ₂ (4)
Γ ₁ = Γ ₂ (5)
In this invention, the diffraction efficiency is kept substantially constant for each wavelength in the visible light region. Accordingly, the diffraction grating functions as an optical low-pass filter that can extract a constant diffracted light intensity with respect to the incident light intensity at each wavelength, and a solid-state imaging device cover that can faithfully reproduce the color tone of the subject in the visible light region is obtained.

The present invention is characterized in that an imaging element cover to satisfy the following equation (6).
d _L = 2.87 × d _H (6)
In the present invention, the zero-order diffraction efficiency in the visible light region can be made substantially the same. Also, the diffraction efficiency of the first-order diffracted light can be set substantially the same.

In the present invention, it is preferable that the first refractive index material is silicon dioxide and the second refractive index material is titanium dioxide or tantalum pentoxide.
In the present invention, since a dielectric having excellent durability as a material for forming a diffraction grating, high have an imaging element cover of reliability.

In the present invention, it is preferable that the first refractive index material is an ultraviolet curable resin or a thermosetting resin, and the second refractive index material is titanium dioxide or tantalum pentoxide.
In the present invention, the material forming the diffraction grating because it contains resins, can cope with cost reduction of an imaging element cover.

In the present invention, the on a first main surface of the diffraction grating, are sequentially arranged 1/4 wavelength plate and a second diffraction grating, the second diffraction grating, the first same shape as the diffraction grating It is preferable that the formation direction of the second diffraction grating and the formation direction of the first diffraction grating are orthogonal to each other.
In the present invention, because of the use by the orthogonal direction of diffraction of the two diffraction gratings are configured optical low-pass filter of the four-point separation, more IMAGING device cover with a high-performance optical low-pass filter is obtained.

In the present invention, on the main surface of the first diffraction grating, is arranged in turn a quarter wavelength plate and the birefringent plate, the diffraction direction of said first diffraction grating, birefringent direction of the birefringent plate Are preferably orthogonal.
In the present invention, the diffraction direction birefringent direction is configured optical low-pass filter of the four-point separation that is substantially perpendicular, more IMAGING device cover with a high-performance optical low-pass filter is obtained.

An image pickup apparatus according to the present invention includes an image pickup element, a package in which the image pickup element is housed, and an image pickup element cover according to claim 1 that seals the package. It is characterized by that.

According to the present invention, as that abolish sealing IMAGING element cover the package is provided with the Z-cut quartz plate of impurities less single crystal such as heavy metals, into α line generation is least for an imaging element An imaging device that prevents damage is obtained.

In the present invention, the optical low-pass filter is preferably a birefringent plate.
In the present invention, in addition to the above-described effect, the birefringent plate constitutes a two-point separation optical low-pass filter. Therefore, the number of parts is small, the structure is simple, and the manufacture is facilitated. Therefore, the image pickup apparatus can be reduced in size, reduced in height, and reduced in price.

In the present invention, the optical low-pass filter includes a horizontal direction separation birefringence plate and a vertical direction separation birefringence plate, and is ¼ between the horizontal direction separation birefringence plate and the vertical direction separation birefringence plate. A wave plate is preferably arranged.
According to the present invention, in addition to the above-described effects, an optical low-pass filter that is separated by four points is constituted by two birefringent plates and a quarter-wave plate, so that an imaging device in which spatial high-frequency components are suppressed can be obtained. It is done.

In the present invention, the optical low-pass filter includes a first diffraction element in which a first refractive index material and a second refractive index material are periodically and alternately arranged on a light transmission surface of the Z-cut quartz plate. It is a lattice.
In the present invention, the ratio W / P between the width W of the first refractive index material and the period P of the first diffraction grating is 0.5,
The height of the first refractive index material from the surface of the Z-cut quartz plate is d _L ,
The height from the surface of the Z-cut quartz plate of the second refractive index material is d _H ,
The refractive index of the first refractive index material for light of wavelength λ ₁ is n _L1 ,
The refractive index of the second refractive index material for the light of the wavelength λ ₁ is n _H1 ,
The refractive index of the first refractive index material for light of wavelength λ ₂ is n _L2 ,
The refractive index of the second refractive index material for the light of the wavelength λ ₂ is n _H2 ,
A phase modulation amount Γ ₁ of the first diffraction grating with respect to the light of the wavelength λ ₁ ,
When the phase modulation amount Γ ₂ of the first diffraction grating with respect to the light of the wavelength λ ₂ is used,
It is desirable to satisfy the following formulas (3) to (5).
Γ ₁ = {(n _H1 −n _L1 ) × d _H + (1−n _L1 ) × (d _L −d _H )} / λ ₁ (3)
Γ ₂ = {(n _H2 −n _L2 ) × d _H + (1−n _L2 ) × (d _L −d _H )} / λ ₂ (4)
Γ ₁ = Γ ₂ (5)
In this invention, the diffraction efficiency is kept substantially constant for each wavelength in the visible light region. Therefore, the diffraction grating functions as an optical low-pass filter retrieve certain diffracted light intensity to incident light intensity at each wavelength, faithfully be that an imaging element cover reproducibility is obtained a color tone of the object in the visible light region.

The present invention is characterized in that an imaging element cover to satisfy the following equation (6).
d _L = 2.87 × d _H (6)
In the present invention, the zero-order diffraction efficiency in the visible light region can be made substantially the same. Also, the diffraction efficiency of the first-order diffracted light can be set substantially the same.

In the present invention, it is preferable that the first refractive index material is silicon dioxide and the second refractive index material is titanium dioxide or tantalum pentoxide .
In the present invention, since a dielectric having excellent durability is used as a material for forming the diffraction grating, a highly reliable imaging device can be obtained.

In the present invention, it is preferable that the first refractive index material is an ultraviolet curable resin or a thermosetting resin, and the second refractive index material is titanium dioxide or tantalum pentoxide .
In the present invention, since the material forming the diffraction grating contains a resin, it is possible to cope with the cost reduction of the imaging device.

In the present invention, a quarter wave plate and a second diffraction grating are sequentially arranged on the main surface of the diffraction grating, and the second diffraction grating has the same shape as the first diffraction grating, It is preferable that the formation direction of the second diffraction grating and the formation direction of the first diffraction grating are orthogonal to each other.
In the present invention, since the diffraction directions of the two diffraction gratings are orthogonal to each other, a four-point separation optical low-pass filter is formed, and an image pickup apparatus having a higher-performance optical low-pass filter can be obtained.

In the present invention, on the main surface of the first diffraction grating, is arranged in turn a quarter wavelength plate and the birefringent plate, the diffraction direction of said first diffraction grating, birefringent direction of the birefringent plate Are preferably orthogonal.
According to the present invention, an optical low-pass filter with a four-point separation in which the birefringence direction and the diffraction direction are substantially orthogonal to each other is configured, and an imaging apparatus having a higher-performance optical low-pass filter is obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
Fig.1 (a) is a schematic perspective view of the solid-state image sensor cover 40 and the imaging device 10 of this embodiment, FIG.1 (b) has shown the front sectional view in (a).
In FIG. 1, the imaging apparatus 10 includes a solid-state imaging device 1, a package 2, and a solid-state imaging device cover 40 that seals the package 2. The solid-state image sensor cover 40 includes a Z-cut quartz plate 3 and a birefringent plate 50.
As is well known, the Z-cut quartz plate 3 is a quartz plate that has been cut so that the normal of the principal surface of the quartz plate is 0 ° with respect to the Z-axis, which is the optical axis of the quartz crystal. The refractive index (ns) of the Z-cut quartz plate 3 is 1.53, and birefringence (depending on the ordinary light refractive index and the extraordinary light refractive index) does not occur.
The solid-state image sensor 1 is housed in the bottom of a bowl-shaped package 2. The opening of the package 2 is closed by fixing the solid-state image sensor cover 40 to the opening by the adhesive 4, and the solid-state image sensor 1 is sealed.
A birefringent plate 50 as an optical low-pass filter 200 having a two-point separation function is provided on the light incident surface 30 of the Z-cut quartz plate 3.

For the solid-state imaging device 1, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), a CPD (Charge Priming Device), or the like can be used.
The package 2 may be formed by molding a ceramic, a thermosetting epoxy resin, a polyphenylene sulfide resin that is a thermoplastic polysulfone, or the like.

As the adhesive 4, a resin made of epoxy, vinyl acetate, acrylic, styrene, cellulose, polyamide, phenol, or the like can be used.
An antireflection layer can be provided on the surface of the birefringent plate 50 in order to prevent reflection on the surface. The antireflection layer is preferably a multilayer antireflection layer that suppresses reflection over the visible light region.

According to this embodiment, there are the following effects.
(1) Since the Z-cut quartz plate 3 made of a single crystal with few impurities such as heavy metals is provided as the solid-state image sensor cover 40 that seals the package 2, the solid-state image sensor 1 is less likely to generate α rays and damage to the solid-state image sensor 1. Thus, it is possible to obtain the solid-state image sensor cover 40 and the imaging device 10 that prevent the above-described problem.

  (2) Since the birefringent plate 50 constitutes the two-point separation optical low-pass filter 200, the number of components is small, the structure is simple, and the manufacturing can be facilitated. Therefore, the solid-state image sensor cover 40 and the imaging device 10 can be reduced in size, reduced in height, and reduced in price.

The second to sixth embodiments are different from the first embodiment in the configuration of the optical low-pass filter.
(Second Embodiment)
2A is a schematic perspective view of the solid-state image sensor cover 41 and the imaging device 100 of the present embodiment, and FIG. 2B shows a front sectional view of FIG.
The solid-state image sensor cover 41 includes a Z-cut crystal plate 3 and an optical low-pass filter 210. In the present embodiment, the optical low-pass filter 210 includes a horizontal direction separating birefringent plate 53, a vertical direction separating birefringent plate 90, and a quarter wavelength plate 8.
A quarter-wave plate 8 is disposed between the horizontal separating birefringent plate 53 and the vertical separating birefringent plate 90.

According to this embodiment, there are the following effects.
(3) Since the four-point separation optical low-pass filter 210 is constituted by the two birefringence plates of the horizontal direction separation birefringence plate 53 and the vertical direction separation birefringence plate 90 and the quarter wavelength plate 8, more space is provided. The solid-state image sensor cover 41 and the imaging device 100 in which the typical high-frequency component is suppressed are obtained.

(Third embodiment)
FIG. 3A is a schematic perspective view of the solid-state image sensor cover 42 and the imaging device 20 of the present embodiment, and FIG. 3B shows a front sectional view of FIG.
The solid-state image sensor cover 42 includes a Z-cut quartz plate 3 and an optical low-pass filter 220. In the present embodiment, the diffraction grating 5 is formed on the incident surface 30 of the incident light of the Z-cut quartz plate 3 as the optical low-pass filter 220. The diffraction grating 5 has irregularities with a periodic cross-sectional shape. In FIG. 3, the cross-sectional shape of the unevenness is a rectangular shape, but may be a trapezoidal shape or the like.
The diffraction grating 5 may be formed by etching the Z-cut quartz crystal plate 3 to form recesses, and a dielectric layer such as silicon dioxide is provided on the projections by a film forming means such as vapor deposition or sputtering. May be formed. Moreover, you may form an unevenness | corrugation using ultraviolet curable resin or a thermosetting resin.

The diffraction grating 5 functions as an optical low-pass filter 220 with two-point separation. The preferred grating height of the diffraction grating 5 is 0.1 to 1 μm, and the width and period of the convex part can be set according to the pixel period of the solid-state imaging device 1.
In FIG. 4, the diffraction efficiency I ₁ of the _first- order diffracted light of the diffraction grating 5 of the present embodiment is shown by a solid line. The horizontal axis represents the wavelength λ and the vertical axis represents the diffraction efficiency I.
The diffraction efficiency I ₁ of the _first- order diffracted light shows a mountain-shaped wavelength dependency having a peak at 600 nm in the visible light region.

  An antireflection layer can be provided on the surface of the diffraction grating 5 and the incident surface 30 in order to prevent reflection on the surface. The antireflection layer is preferably a multilayer antireflection layer that suppresses reflection over the visible light region.

According to this embodiment, there are the following effects.
(4) The diffraction grating 5 is integrally formed on the Z-cut quartz plate 3 to constitute one component, and the number of components can be reduced as the entire solid-state imaging device cover 42 and the imaging device 20. Therefore, the solid-state image sensor cover 42 and the imaging device 20 can be reduced in size, reduced in height, and reduced in price.

(Fourth embodiment)
FIG. 5A is a front sectional view of the solid-state imaging device cover 43 and the imaging device 60 of the present embodiment, and FIG. 5B is an enlarged front sectional view of FIG.
The solid-state image sensor cover 43 includes a Z-cut crystal plate 3 and an optical low-pass filter 230. This embodiment differs from the third embodiment in the configuration of the diffraction grating.
In FIG. 5A, the difference from the third embodiment is that the optical low-pass filter 230 provided on the incident surface 30 of the Z-cut quartz crystal plate 3 is a diffraction grating whose cross-sectional shape is periodic unevenness. The diffraction grating is that the convex portion 6 is made of a low refractive index material and the concave portion 7 is made of a high refractive index material.

  Below, with reference to FIG.5 (b), the relationship between the thickness of the convex part 6 and the thickness of the recessed part 7 is demonstrated. These thicknesses are set so that the diffraction efficiency I in the visible light region is substantially constant.

The ratio W / P between the width W of the protrusion 6 and the period P is set to 0.5.
The thickness of the convex portion 6 is d _L , the refractive index is n _L , the thickness of the concave portion 7 is d _H , and the refractive index is n _H.
Here, when the diffraction efficiency of the m-th order diffracted light of the diffraction efficiency is I _m , the diffraction efficiency I _m can be expressed by a function such as the expression (1) by P, W, and Γ.
I _m = f (P, W, Γ) (1)
Γ is a phase modulation amount.
Since the phase modulation amount Γ varies depending on the wavelength, in order to make the diffraction efficiency _{Im the} same value at different wavelengths, it is only necessary to compensate so that the phase modulation amount Γ does not change even if the wavelength changes.

The phase modulation amount Γ can be expressed as shown in Equation (2).
Γ = {(n _H −n _L ) d _H + (1−n _L ) (d _L −d _H )} / λ (2)
Here, the refractive index of the convex portion 6 at the wavelength λ ₁ is n _L1 , the refractive index of the concave portion 7 is n _H1 , the refractive index of the convex portion 6 at the wavelength λ ₂ is n _L2 , and the refractive index of the concave portion 7 is n. When _H2, the phase modulation amount gamma ₂ in the phase modulation amount gamma _1, and the wavelength lambda ₂ at a wavelength lambda ₁ of the formula (3), can be expressed as (4).
Γ ₁ = {(n _H1 −n _L1 ) d _H + (1−n _L1 ) (d _L −d _H )} / λ ₁ (3)
Γ ₂ = {(n _H2 −n _L2 ) d _H + (1−n _L2 ) (d _L −d _H )} / λ ₂ (4)
In order to make the diffraction efficiencies _{Im the} same at the wavelengths λ ₁ and λ ₂ , Γ ₁ = Γ ₂ suffices, so each condition may be set so as to satisfy Expression (5).
{(N _H1 −n _L1 ) d _H + (1−n _L1 ) (d _L −d _H )} / λ ₁ = {(n _H2 −n _L2 ) d _H + (1−n _L2 ) (d _L − d _H )} / λ ₂ (5)

Next, assuming the visible light region, the relationship between d _L and d _H is obtained.
The convex portion 6 is silicon dioxide, the concave portion 7 is tantalum pentoxide, the wavelength λ ₁ is 400 nm, and the wavelength λ ₂ is 700 nm. The refractive indexes of silicon dioxide and tantalum pentoxide at each wavelength λ ₁ and λ ₂ are as follows. When the wavelength λ ₁ = 400 nm, the refractive index of silicon dioxide is 1.495, the refractive index of tantalum pentoxide is 2.312, and when the wavelength λ ₂ = 800 nm, the refractive index of silicon dioxide is 1.467, five The refractive index of tantalum oxide is 2.158.
By substituting these values into equation (5), the result of equation (6) is obtained.
d _L = 2.87 d _H (6)

Therefore, if the thickness d _L of the convex portion 6 and the thickness d _{H of the} concave portion 7 are set so as to satisfy Expression (6), the diffraction efficiency I ₀ of the _0th- order diffracted light in the visible light region can be set to be substantially the same. it can. Also, the diffraction efficiency I _{1 of the first-} order diffracted light can be set substantially the same.
Here, considering the case of separation into two points, the zero-order diffracted light has a diffraction efficiency I ₀ of approximately 0, and the diffraction efficiency I _{1 of the first-} order diffracted light has only to be set to the maximum. = Γ2 = 0.5 is sufficient. Further, d _H and d _L are obtained by substituting Equation (6) into Equation (3), and d _H = 1872 nm and d _L = 5374 nm are obtained. The value obtained here is the optimum value at the wavelength λ ₁ = 400 nm. Therefore, in order to obtain the best efficiency in the visible light range, d _H and d _L were finely adjusted using the formula (2) and optimized within the wavelength range to be used. As a result, d _H = 1700 nm and d _L = 4878 nm were obtained.

FIG. 6 shows the result of simulating the relationship between the wavelength and the diffraction efficiencies I ₀ and I ₁ .
Before the optimization, the results when the thickness d _L = 5374 nm of the convex portion 6 and the thickness d _H = 1872 nm of the concave portion 7 which are the optimum values at the wavelength λ ₁ = 400 nm are shown by thin lines.
After optimization, the results when the thickness d _L = 4878 nm of the convex portion 6 and the thickness d _H = 1700 nm of the concave portion 7 that are further optimized within the wavelength range to be used are shown by bold lines.
From the simulation results shown in FIG. 6, by optimizing the thickness d _L of the convex portion 6 and the thickness d _{H of the} concave portion 7, the diffraction efficiency I ₁ in the visible light region can be set to be substantially the same, and the zero-order light can be set. It was confirmed that the peak of the diffraction efficiency I ₀ disappeared and the zero-order light was hardly diffracted.

In the case where silicon dioxide or tantalum pentoxide dielectric is used for the convex portion 6 and the concave portion 7, for example, the convex portion 6 and the concave portion 7 are formed as follows.
After a silicon dioxide film is formed on the Z-cut quartz plate 3 by film deposition means such as vacuum deposition or sputtering, the silicon dioxide film is etched and patterned by photolithography and etching methods to form convex portions 6, and the silicon dioxide film is formed. Titanium dioxide or tantalum pentoxide is formed in the removed portion by vacuum deposition or sputtering to form the recess 7.

When an ultraviolet curable resin is used for the convex portion 6, for example, a diffraction grating is formed as follows.
Titanium dioxide or tantalum pentoxide is formed on the Z-cut quartz plate 3 by vacuum deposition or sputtering. Next, etching is selectively performed by a photolithography method and an etching method. An ultraviolet curable resin is applied to the place from which titanium dioxide or tantalum pentoxide has been removed, and exposed to ultraviolet rays from the back side through the Z-cut quartz plate 3 to be exposed. In the portion where titanium dioxide or tantalum pentoxide is present, the transmittance of ultraviolet rays is reduced, and the ultraviolet curable resin is not sensitized. Therefore, the uncured ultraviolet curable resin can be removed using the stripping solution.

  In addition to the photolithography method and the etching method, a lattice may be formed using a mold having a nano-order pattern called a nanoimprint technique.

According to this embodiment, in addition to the effects of the third embodiment, there are the following effects.
(5) The diffraction efficiency I ₁ of the _first- order diffracted light can be kept substantially constant for each wavelength in the visible light region, and the diffraction efficiency I ₀ of the _zero- order diffracted light can be reduced. Therefore, the convex portion 6 and the concave portion 7 function as an optical low-pass filter 230 that can extract a constant diffracted light intensity with respect to the incident light intensity at each wavelength, and the solid-state image sensor cover 43 that can faithfully reproduce the color tone of the subject in the visible light region. And the imaging device 60 can be obtained.

  (6) Since a dielectric having excellent durability is used as a material for forming the convex portions 6 and the concave portions 7, the solid-state imaging element cover 43 and the imaging device 60 with high reliability can be obtained.

  (7) When a resin is used as the low refractive index material, it is possible to cope with the cost reduction of the solid-state image sensor cover 43 and the imaging device 60.

(Fifth embodiment)
In this embodiment, the optical low-pass filter 230 obtained in the fourth embodiment is further combined with another diffraction grating to form a four-point separation optical low-pass filter 240.
FIG. 7A shows a schematic perspective view of the solid-state image sensor cover 44 and the imaging device 110 of the present embodiment. (B) is a front sectional view.
A quarter-wave plate 8 is disposed on the diffraction grating composed of the convex portions 6 and the concave portions 7, and a Z-cut quartz plate 31 on which the diffraction grating 51 is formed is further disposed thereon.
The diffraction grating 51 is composed of two types of refractive index materials, a convex portion having a low refractive index material and a concave portion having a high refractive index material, as in the diffraction grating formed of the convex portion 6 and the concave portion 7 formed on the Z-cut quartz crystal plate 3. Even if it consists of the comprised diffraction grating, it may consist of the diffraction grating comprised by one type of refractive index material like FIG. 3 of above-mentioned 3rd Embodiment.
Further, the diffraction grating 51 is arranged so that the diffraction direction thereof is substantially orthogonal to the diffraction direction of the diffraction grating composed of the convex portions 6 and the concave portions 7.

According to this embodiment, there are the following effects.
(8) Since the diffraction direction of the diffraction grating 51 and the diffraction grating composed of the convex part 6 and the concave part 7 are used orthogonally, a four-point separation optical low-pass filter 240 is formed, and a higher-performance optical low-pass filter 240 is formed. Can be obtained.

(Sixth embodiment)
In the present embodiment, the optical low-pass filter 230 obtained in the fourth embodiment is further combined with the birefringent plate 9 to form a four-point separation optical low-pass filter 250.
FIG. 8A shows a schematic perspective view of the solid-state image sensor cover 45 and the imaging device 120 of the present embodiment. (B) is a front sectional view.
A quarter-wave plate 8 is disposed on the diffraction grating composed of the convex portions 6 and the concave portions 7, and a birefringent plate 9 is further disposed thereon.
The birefringent plate 9 is disposed so that the birefringence direction thereof is substantially orthogonal to the diffraction direction of the diffraction grating composed of the convex portions 6 and the concave portions 7.

According to this embodiment, there are the following effects.
(9) The four-point separation optical low-pass filter 250 in which the birefringence direction and the diffraction direction are substantially orthogonal to each other is configured, and the solid-state image sensor cover 45 and the imaging device 120 including the higher-performance optical low-pass filter 250 can be obtained. .

  It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  The best method for carrying out the present invention has been disclosed in the above description, but the present invention is not limited to this. In other words, the present invention has been mainly described with reference to specific embodiments, but the materials, shapes, and other materials used for the above-described embodiments are not deviated from the technical idea and the scope of the present invention. In detail, various modifications can be made by those skilled in the art. Accordingly, the description of the materials, shapes, and the like disclosed above is exemplary for ease of understanding of the present invention, and does not limit the present invention. Descriptions excluding some or all of the limitations are included in the present invention.

(A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 1st Embodiment of this invention, (b) is a front sectional view. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 2nd Embodiment of this invention, (b) is a front sectional view. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 3rd Embodiment of this invention, (b) is a front sectional view. The figure which shows the diffraction efficiency of 3rd Embodiment. (A) is a front sectional view of a solid-state image sensor cover and an imaging device concerning a 4th embodiment of the present invention, and (b) is an enlarged front sectional view. The figure which showed the relationship between a wavelength and diffraction efficiency. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 5th Embodiment of this invention, (b) is a front sectional view. (A) is a schematic perspective view of the solid-state image sensor cover and imaging device concerning 6th Embodiment of this invention, (b) is front sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor, 2 ... Package, 3,31 ... Z cut crystal plate, 5,51 ... Diffraction grating, 6 ... Convex part, 7 ... Concave part, 8 ... 1/4 wavelength plate, 9,50 ... Birefringent plate DESCRIPTION OF SYMBOLS 10,20,60,100,110,120 ... Imaging device, 30 ... Incident surface, 40, 41, 42, 43, 44, 45 ... Solid-state image sensor cover, 53 ... Horizontal direction separation birefringent plate, 90 ... Vertical Direction separating birefringent plates, 200, 210, 220, 230, 240, 250... Optical low-pass filter.

Claims (11)

The package of an imaging device is housed a IMAGING element cover that abolish sealed,
Before SL is IMAGING element cover, it characterized IMAGING element cover that includes an optical low-pass filter provided on the transmitting surface of the optical Z-cut quartz crystal plate and the Z-cut quartz plate. Oite to claim 1,
The optical low-pass filter, it characterized IMAGING element cover to be a birefringent plate. Oite to claim 1,
The optical low-pass filter comprises a horizontal separation birefringence plate and a vertical separation birefringence plate,
The horizontal separation between the birefringent plate and the vertical separating birefringent plate, 1/4 characterized IMAGING element covers the wavelength plate is disposed. In claim 1,
The optical low-pass filter is a first diffraction grating in which a first refractive index material and a second refractive index material are periodically and alternately arranged on a light transmission surface of the Z-cut quartz plate. An image sensor cover characterized by .   In claim 4,
  The ratio W / P of the width W of the first refractive index material to the period P of the first diffraction grating is 0.5;
  The height of the first refractive index material from the surface of the Z-cut quartz plate is d _L age,
  The height of the second refractive index material from the surface of the Z-cut quartz plate is d _H age,
  Wavelength λ ₁ The refractive index of the first refractive index material for n light is n _L1 age,
  The wavelength λ ₁ The refractive index of the second refractive index material for n light is n _H1 age,
  Wavelength λ ₂ The refractive index of the first refractive index material for n light is n _L2 age,
  The wavelength λ ₂ The refractive index of the second refractive index material for n light is n _H2 age,
  The wavelength λ ₁ Phase modulation amount Γ of the first diffraction grating for light of ₁ age,
  The wavelength λ ₂ Phase modulation amount Γ of the first diffraction grating for light of ₂ When
  An imaging element cover characterized by satisfying the following formulas (3) to (5).
Γ ₁ = {(N _H1 -N _L1 ) Xd _H + (1-n _L1 ) X (d _L -D _H )} / Λ ₁ ... (3)
Γ ₂ = {(N _H2 -N _L2 ) Xd _H + (1-n _L2 ) X (d _L -D _H )} / Λ ₂ ... (4)
Γ ₁ = Γ ₂ ... (5)   The imaging element cover according to claim 5, wherein the following expression (6) is satisfied.
d _L = 2.87 x d _H ... (6)   The first refractive index material is silicon dioxide;
  The image sensor cover according to claim 5 or 6, wherein the second refractive index material is titanium dioxide or tantalum pentoxide.   The first refractive index material is an ultraviolet curable resin or a thermosetting resin,
  The image sensor cover according to claim 5 or 6, wherein the second refractive index material is titanium dioxide or tantalum pentoxide.   On the main surface of the first diffraction grating, a quarter-wave plate and a second diffraction grating are sequentially arranged,
  The second diffraction grating has the same shape as the first diffraction grating,
  The imaging element cover according to claim 4, wherein a formation direction of the second diffraction grating and a formation direction of the first diffraction grating are orthogonal to each other.   On the main surface of the first diffraction grating, a quarter-wave plate and a birefringent plate are sequentially arranged,
  The imaging element cover according to claim 4, wherein a diffraction direction of the first diffraction grating and a birefringence direction of the birefringent plate are orthogonal to each other.   An image sensor;
  A package in which the image sensor is housed;
  The image sensor cover according to any one of claims 1 to 10, wherein the package is sealed;
An imaging apparatus comprising:

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