JP4978105B2 - 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)

When the diffraction grating is used as an optical low-pass filter, there is a problem that a certain diffraction efficiency cannot be obtained over each wavelength in the visible light region, and an intensity difference occurs depending on the wavelength, so that the color tone of the subject cannot be faithfully reproduced.
An object of the present invention is to obtain a solid-state image sensor cover and an imaging apparatus that can faithfully reproduce the color tone of a subject in the visible light region while corresponding to downsizing, low profile, and low price.

An imaging element cover of the present invention is a that IMAGING element cover resign sealed packages IMAGING element is housed, prior Symbol IMAGING element cover, and the light-transmitting substrate, the transparent substrate wherein between the first diffraction grating first refractive index material and a second refractive index material are alternately on arranged on the main surface, and the width W of the first refractive index material No. The ratio W / P with the period P of one diffraction grating is 0.5, the height of the first refractive index material from the surface of the translucent substrate is d _L, and the second refractive index The height of the material from the surface of the translucent substrate is d _H , the refractive index of the first refractive index material with respect to the light with the wavelength λ ₁ is n _L1, and the second with respect to the light with the wavelength λ ₁ the refractive index of the refractive index material and n _H1, the refractive index of the first refractive index material for the wavelength lambda ₂ of the light and n _L2, with respect to the wavelength lambda ₂ of light Serial refractive index of the second refractive index material and n _H2, the wavelength lambda ₁ and the phase modulation amount gamma ₁ of the first diffraction grating to light, of the first diffraction grating with respect to the wavelength lambda ₂ of light When the phase modulation amount is Γ ₂ ,
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)
It is characterized by satisfying .

  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.

  In the present invention, it is preferable that the following formula (6) is satisfied.
  d _L = 2.87 x d _H   ... (6)
  It is possible to set the diffraction efficiency of the zero next-order diffraction light in the visible light region to be approximately the same. Further, 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 any one of titanium dioxide and 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 any one of an ultraviolet curable resin and a thermosetting resin, and the second refractive index material is any one of titanium dioxide and tantalum pentoxide.
In this invention, the first refractive index materials because it contains resins, it can cope with cost reduction of an imaging element cover.

In the present invention, on the main surface of the first diffraction grating, they are sequentially arranged 1/4 wavelength plate and a second diffraction grating, before Symbol second diffraction grating, said first diffraction grating It is preferable that the second diffraction grating is formed in the same shape and the first diffraction grating is formed in an orthogonal relationship with the formation direction of the first diffraction grating.
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, the on a first main surface of the diffraction grating is arranged in turn a quarter wavelength plate and the birefringent plate, the diffraction direction of said first diffraction grating, the birefringence of the birefringent plate The direction is preferably orthogonal to the direction.
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.

Imaging apparatus of the present invention is a that IMAGING element cover resign sealed packages IMAGING element is housed, prior Symbol IMAGING element cover, and the light-transmitting substrate, the main of the light-transmitting substrate includes a first diffraction grating first refractive index material and a second refractive index material are mutually arranged exchange on the surface, and the width W of the first refractive index material of the first The ratio W / P with respect to the period P of the diffraction grating is 0.5, the height of the first refractive index material from the surface of the translucent substrate is d _L, and the second refractive index material The height from the surface of the translucent substrate is d _H , the refractive index of the first refractive index material for light of wavelength λ ₁ is n _L1, and the second refractive index for light of wavelength λ _1. the refractive index of the material and n _H1, the refractive index of the first refractive index material for the wavelength lambda ₂ of the light and n _L2, the with respect to the wavelength lambda ₂ of the light first Of the refractive index of the refractive index material and n _H2, the wavelength lambda ₁ and the phase modulation amount gamma ₁ of the first diffraction grating to light, the phase modulation amount of the first diffraction grating with respect to the wavelength lambda ₂ of light When Γ ₂
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)
It is characterized by satisfying .

  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 that can extract a constant diffracted light intensity with respect to the incident light intensity at each wavelength, and an imaging apparatus that can faithfully reproduce the color tone of the subject in the visible light region can be obtained.

  In the present invention, it is preferable that the following formula (6) is satisfied.
  d _L = 2.87 x d _H   ... (6)
  It is possible to set the diffraction efficiency of the zero next-order diffraction light in the visible light region to be approximately the same. Further, the diffraction efficiency of the first-order diffracted light can be set substantially the same.

In the present invention, the first refractive index material silicon dioxide, preferably the second refractive index material and one of titanium dioxide and 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, the first refractive index material as either of the ultraviolet curable resin and a thermosetting resin, preferably the second refractive index material is either titanium dioxide and tantalum pentoxide.
In the present invention, since the first refractive index material contains a resin, it is possible to cope with the cost reduction of the imaging device.

In the present invention, the on a first main surface of the diffraction grating, and in turn the quarter-wave plate and a second diffraction grating arranged, the second diffraction grating is equal to 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, the on a first main surface of the diffraction grating is arranged in turn a quarter wavelength plate and the birefringent plate, the diffraction direction of said first diffraction grating, the birefringence of the birefringent plate The direction is preferably orthogonal to the direction.
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 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.

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, or a polyphenylene sulfide resin that is a thermoplastic polysulfone.

  The solid-state image sensor cover 40 includes a glass cover 3 and a diffraction grating 5. The diffraction grating 5 is formed on the light incident surface 30 of the glass cover 3.

For the glass cover 3, glass that transmits light in the visible light region can be used. As glass, quartz glass, borosilicate glass, soda glass, or the like can be used.
Incident light from the outside passes through the solid-state image sensor cover 40 and reaches the solid-state image sensor 1 in the package 2.
The diffraction grating 5 has irregularities with a periodic cross-sectional shape. In FIG. 1, the convex and concave portions 52 and the concave portions 53 are rectangular in cross section, but may be trapezoidal or the like.
As a method for forming the diffraction grating 5, a method may be used in which the concave portion 53 is formed by etching the incident surface 30 of the glass cover 3 to form the concave and convex portions. Moreover, you may form the convex part 52 in the incident surface 30 of the glass cover 3 by film-forming means, such as vapor deposition and a sputtering, etc., dielectric layers, such as a silicon dioxide. Furthermore, you may form the convex part 52 using an ultraviolet curable resin or a thermosetting resin.

The diffraction grating 5 functions as an optical low-pass filter 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 portion 52 can be set according to the pixel period of the solid-state imaging device 1.
In FIG. 2, the diffraction efficiency I ₁ of the _first- order diffracted light of the diffraction grating 5 of this 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.

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 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.
(1) The diffraction grating 5 is integrally formed on the glass cover 3 to constitute one component, and the number of components can be reduced as the solid-state image sensor cover 40 and the entire imaging apparatus 10. 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.

  (2) Since the concave portion 53 is directly formed on the incident surface 30 of the glass cover 3, the number of parts can be further reduced.

  (3) Since a dielectric having excellent durability is used as the material for forming the diffraction grating 5, the solid-state image sensor cover 40 and the imaging device 10 having high reliability can be obtained.

  (4) Since the convex part 52 contains resin, it can respond to the cost reduction of the solid-state image sensor cover 40 and the imaging device 10. FIG.

(Second Embodiment)
3A is a front sectional view of the solid-state image sensor cover 41 and the imaging device 20 of the present embodiment, and FIG. 3B is an enlarged front sectional view of FIG.
In FIG. 3A, the difference from the first embodiment is that a diffraction grating 51 having a convex portion 6 and a concave portion 7 is formed on the incident surface 30 of the glass cover 3.
The convex portions 6 and the concave portions 7 are alternately arranged, and the cross-sectional shape is a periodic unevenness.
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.3 (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 diffraction efficiency I ₀ of the 0th-order diffracted light may be set to approximately 0, and the diffraction efficiency I _{1 of the 1st-} order diffracted light may 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 _L = 5374 nm and d _H = 1873 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. 4 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. 4, 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 glass cover 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 removed. Titanium dioxide or tantalum pentoxide is formed at the location 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 glass cover 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 is exposed to ultraviolet rays from the back side through the glass cover 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 first 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. Accordingly, the convex portion 6 and the concave portion 7 function 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 the solid-state image sensor cover 41 that can faithfully reproduce the color tone of the subject in the visible light region. The imaging device 20 can be obtained.

(Third embodiment)
In the present embodiment, the solid-state image sensor cover 41 obtained in the second embodiment is further combined with another diffraction grating to provide the function of a four-point separation optical low-pass filter.
FIG. 5A shows a schematic perspective view of the solid-state image sensor cover 42 and the imaging apparatus 100 of the present embodiment. FIG. 2B is a front sectional view in FIG.
On the convex part 6 and the concave part 7, the quarter wavelength plate 8 is arrange | positioned, Furthermore, the glass cover 31 in which the diffraction grating 54 was formed is arrange | positioned on it.
The diffraction grating 54 may be composed of two diffraction gratings as in the case of the convex portions 6 and the concave portions 7 formed on the glass cover 3 or may be composed of one diffraction grating.
The diffraction grating 54 is arranged so that the diffraction direction thereof is substantially orthogonal to the diffraction directions of the convex portions 6 and the concave portions 7.

According to this embodiment, there are the following effects.
(6) Since the diffractive directions of the convex portion 6 and the concave portion 7 and the diffraction grating 54 are orthogonal to each other, a four-point separation optical low-pass filter is configured, and a solid-state imaging device having a higher-performance optical low-pass filter The cover 42 and the imaging device 100 can be obtained.

(Fourth embodiment)
In this embodiment, the solid-state imaging device cover 41 obtained in the second embodiment is further combined with a birefringent plate 9 to provide a function of an optical low-pass filter with four-point separation.
FIG. 6A shows a schematic perspective view of the solid-state imaging device cover 43 and the imaging device 110 of the present embodiment. FIG. 2B is a front sectional view in FIG.
A quarter-wave plate 8 is disposed on the convex portions 6 and the concave portions 7, and a birefringent plate 9 is disposed thereon.
The birefringent plate 9 is arranged so that the birefringence direction thereof is substantially orthogonal to the diffraction directions of the convex portions 6 and the concave portions 7.

According to this embodiment, there are the following effects.
(7) A four-point separation optical low-pass filter in which the birefringence direction and the diffraction direction are substantially orthogonal to each other is configured, and the solid-state image sensor cover 43 and the imaging device 110 having a higher-performance optical low-pass filter 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. The figure which shows the diffraction efficiency of 1st Embodiment. (A) is a front sectional view of a solid-state image sensor cover and an imaging device concerning a 2nd 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 3rd 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 4th Embodiment of this invention, (b) is a front sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor, 2 ... Package, 3, 31 ... Glass cover, 5, 51, 54 ... Diffraction grating, 6, 52 ... Convex part, 7, 53 ... Concave part, 8 ... 1/4 wavelength plate, 9 ... Multiple Refractive plate, 10, 20, 100, 110... Imaging device, 30... Entrance surface, 40, 41, 42, 43.

Claims (7)

The package of an imaging device is housed a IMAGING element cover that abolish sealed,
Before Symbol An imaging element cover,
A translucent substrate ;
A first diffraction grating first refractive index material and a second refractive index material are alternately on disposed on the main surface of the transparent substrate,
Including
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 translucent substrate is d _L ,
The height of the second refractive index material from the surface of the translucent substrate 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,
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)
It characterized IMAGING element cover that satisfies the. In claim 1,
d _L = 2.87 × d _H (6)
An imaging device cover according to, characterized in that it satisfies the. In claim 1 or 2,
The first refractive index material is silicon dioxide;
Wherein either as it characterized by being IMAGING element cover of the second refractive index titanium dioxide material and tantalum pentoxide. In claim 1 or 2,
Said first refractive index material as either of the ultraviolet curable resin and a thermosetting resin,
Wherein either as it characterized by being IMAGING element cover of the second refractive index titanium dioxide material and tantalum pentoxide. In any one of Claims 1 thru | or 4,
On the main surface of the first diffraction grating, and in turn the quarter-wave plate and the second diffraction grating is arranged,
The second diffraction grating is the first same shape as the diffraction grating,
Wherein the forming direction of the second diffraction grating, to that an imaging device cover, characterized in that an orthogonal relationship to the forming direction of the first diffraction grating. In any one of Claims 1 thru | or 4,
On the main surface of the first diffraction grating, a quarter-wave plate and a birefringent plate are arranged in order,
It said first diffraction direction of the diffraction grating, you characterized IMAGING element cover that are orthogonal to the birefringence direction of the birefringent plate. And an imaging element,
And packages before Symbol an imaging element is housed,
Taking a picture element cover according to any one of the package according to claim 1 to 6 that are sealed,
Imaging device according to claim Tei Rukoto equipped with.

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