WO2018180269A1 - Optical element and manufacturing method for optical element - Google Patents

Abstract

The present invention provides an optical element in which a deflection element for bending light and an optical filter are integrated and which causes little light loss and is easy to manufacture, and further provides a method for simply and easily manufacturing an optical element in which a deflection element and an optical filter are integrated by an adhesion layer. This optical element is provided with: a deflection element which deflects and emits incident light; an optical filter which is located on the incidence side or emission side of the deflection element, and selectively blocks light in at least part of a region ranging from an ultraviolet region to a near-infrared region; and an adhesion layer which integrates the deflection element and the optical filter therebetween, wherein the relations of expression (1) and expression (2) are satisfied: ΔnGF = |nG-nF| ≤ 0.5 … (1), ΔnPG = |nP-nG| ≤ 0.5 … (2) where nP is the refractive index of the deflection element, nG is the refractive index of the adhesion layer, and nF is the refractive index of a member having a maximum layer thickness among members included in the optical filter.

Description

Optical element and optical element manufacturing method

The present invention relates to an optical element and a method for manufacturing the optical element.

In a digital still camera or the like, an image pickup apparatus equipped with a solid-state image pickup device such as a CCD or a CMOS image sensor has been further reduced in size and functionality. For example, in an image pickup apparatus including a coupled lens system such as a zoom lens and a solid-state image pickup device, the size can be reduced by using a deflection element such as a prism that bends light.

Patent Document 1 includes a prism that bends light transmitted through an imaging lens group, and a cover glass that transmits light bent by the prism, and includes an exit surface of the prism that emits light, and an incident surface of the cover glass. Describes an imaging apparatus using an optical component bonded with an optically transparent adhesive.

JP 2012-68509 A

The present invention provides an optical element that integrates a deflecting element that bends light and an optical filter and that is easy to manufacture with little light loss, and an optical element in which the deflecting element and the optical filter are integrated by an adhesive layer. The object is to provide a manufacturing method.

The optical element of the present invention selectively deflects light that deflects incident light and emits light in at least a part of the region from the ultraviolet region to the near infrared region that is located on the incident side or the emission side of the deflection element. And an adhesive layer that integrates both between the deflection element and the optical filter, the refractive index of the deflection element is n _P , the refractive index of the adhesive layer is n _G , and When the refractive index of the member having the maximum layer thickness among the members included in the optical filter is n _F , the relationship of the following expressions (1) and (2) is satisfied.
Δn _GF = | n _G −n _F | ≦ 0.5 (1)
Δn _PG = | n _P −n _G | ≦ 0.5 (2)

The optical element manufacturing method of the present invention includes a deflection element that deflects and emits incident light, and light in at least a part of the region from the ultraviolet region to the near infrared region that is located on the incident side or the emission side of the deflection element. And an adhesive layer that integrates both between the deflection element and the optical filter, the refractive index of the deflection element is n _P , and the refractive index of the adhesive layer is n _G , and when the out layer thickness of members included in the optical filter has a refractive index of the largest member with _{n F, Δn GF = | n} G -n F | ≦ 0.5 and Δn _PG = _| n P -n _G | ≦ 0.5, a method for producing an optical element, comprising an adhesive layer forming composition layer containing an ultraviolet curable material between the deflection element and the optical filter. A step of producing a precursor, and said optics In the case where the optical element is used as a child precursor, the composition layer for forming the adhesive layer is cured by irradiating light in the ultraviolet region from the side which becomes the incident side when the optical element is used or the side which becomes the outgoing side when the optical element is used. Including a step of forming an adhesive layer.

According to the present invention, it is possible to provide an optical element that integrates a deflecting element that bends light and an optical filter and that is easy to manufacture with little optical loss. Further, according to the present invention, it is possible to provide a method for easily manufacturing an optical element in which a deflection element and an optical filter are integrated by an adhesive layer.

In an image pickup apparatus, if the optical element of the present invention is disposed and used immediately before the light receiving surface of a solid-state image pickup element, it is advantageous for downsizing of the image pickup apparatus.

It is sectional drawing which shows an example of the optical element of embodiment. It is sectional drawing which shows roughly an example of an imaging device provided with the optical element of embodiment. It is sectional drawing which shows typically the relationship between the incident angle of light in the optical element of embodiment, and an output angle. It is a graph showing the refractive index n _P for totally reflecting the incident angle theta _m in a right angle prism. It is sectional drawing which shows an example of the deflection | deviation element used for the optical element of embodiment. It is sectional drawing which shows an example of the optical filter used for the optical element of embodiment. It is sectional drawing which shows another example of the optical filter used for the optical element of embodiment. It is sectional drawing which shows another example of the optical filter used for the optical element of embodiment. It is a graph which shows the relationship between the refractive index sum and reflectance in the optical interface of different refractive index (n1, n2). It is sectional drawing which shows another example of the optical element of embodiment. It is sectional drawing which shows an example of the optical element of embodiment which has a light shielding film. FIG. 9B is a plan view of the optical element shown in FIG. 9A. It is sectional drawing which shows the modification of the optical element of embodiment which has a light shielding film. It is sectional drawing which shows the modification of the optical element of embodiment which has a light shielding film. It is a perspective view which shows the modification of the optical element of embodiment which has a light shielding film. It is sectional drawing which shows the modification of the optical element of embodiment which has a light shielding film. FIG. 13B is a plan view of the optical element shown in FIG. 13A. It is sectional drawing which shows the modification of the optical element of embodiment which has a light shielding film. FIG. 14B is a plan view of the optical element shown in FIG. 14A. It is sectional drawing which shows the optical element of a manufacture example.

Hereinafter, embodiments of the present invention will be described. In this specification, ultraviolet light or ultraviolet light is abbreviated as “UV”, and near infrared light or near infrared light is abbreviated as “NIR” as necessary. In this specification, “refractive index” means a refractive index with respect to light having a wavelength of 589 nm. “Curable material” refers to an uncured material that is cured by heating or light irradiation to become a cured material, and “cured material” is obtained by curing the curable material by heating or light irradiation. This refers to the cured product. In this specification, “to” representing a numerical range includes upper and lower limits.

In this specification, the “incident side” of an optical element refers to a side where light enters the optical element from the light entering direction along the optical axis of the imaging device or the like when used. The “emission side” of the optical element refers to a side on which light incident from the incident side of the optical element is deflected and emitted in a predetermined direction, for example, the direction of the element that receives the emitted light.

[Optical element]
An optical element according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the optical element of the present embodiment. FIG. 2 is a cross-sectional view schematically showing an example of an imaging apparatus including the optical element of the present embodiment shown in FIG.

An optical element 10 shown in FIG. 1 selectively deflects incident light and deflects and emits light in at least a part of the region from the ultraviolet region to the near infrared region located on the exit side of the deflecting element 1. An optical filter 2 to be blocked, and an adhesive layer 3 that is located between the deflection element 1 and the optical filter 2 and that integrates the deflection element 1 and the optical filter 2 are provided. In the optical element 10 shown in FIG. 1, the optical filter 2 is located on the exit side of the deflecting element 1, but in the optical element of the present invention, the optical filter 2 may be located on the incident side of the deflecting element 1. In this case, the optical element 10 is arranged in the order of the optical filter 2, the adhesive layer 3, and the deflection element 1 from the light incident side.

In FIG. 1, for convenience of explanation, a direction in which light is emitted from the deflection element 1 is defined as a Z-axis direction, and two directions perpendicular to the Z-axis direction and perpendicular to each other are defined as an X-axis direction (a direction perpendicular to the paper surface). The Y-axis direction (direction parallel to the paper surface) is defined. In this specification, the Z-axis direction is referred to as the “Z direction”. The same applies to the X-axis direction and the Y-axis direction. In this specification, unless otherwise specified, the X direction, the Y direction, and the Z direction are the same as those shown in FIG. 1 and 2 are YZ sectional views.

In the optical element 10, the refractive index of the deflecting element 1 is n _P , the refractive index of the adhesive layer 3 is n _G , and the member having the largest layer thickness among the members included in the optical filter 2 (hereinafter referred to as “thickest member”). when the refractive index of say) was n _F, satisfy the relation of the following formula (1) and the following formula (2).
Δn _GF = | n _G −n _F | ≦ 0.5 (1)
Δn _PG = | n _P −n _G | ≦ 0.5 (2)

Hereinafter, the refractive index of the deflecting element is also referred to as “refractive index n _P ”, the refractive index of the adhesive layer is also referred to as “refractive index n _G ”, and the refractive index of the thickest member included in the optical filter is also referred to as “refractive index n _F ”.

The deflection element 1 is a right-angle prism, and has an incident surface 1a on which light is incident, a reflecting surface 1b that reflects incident light, and an emitting surface 1c that emits reflected light. The adhesive layer 3 and the optical filter 2 each have two main surfaces parallel to the emission surface 1 c of the deflection element 1. One of the two main surfaces of the adhesive layer 3 is a main surface in contact with the output surface 1c of the deflecting element 1, and is an incident surface 3a on which light emitted from the deflecting element 1 is incident, and the other emits the light. This is the exit surface 3b. One of the two main surfaces of the optical filter 2 is a main surface in contact with the output surface 3b of the adhesive layer 3, and is an incident surface 2a on which light emitted from the adhesive layer 3 enters, and the other emits the light. This is the emission surface 2b.

In the optical element 10, the light is incident on the incident surface 1 a of the deflecting element 1 from the Y direction, deflected by reflection on the reflecting surface 1 b of the deflecting element 1, and then emitted from the emitting surface 1 c of the deflecting element 1 in the Z direction. The light passes through the adhesive layer 3 and the optical filter 2 and is emitted from the emission surface 2 b of the optical filter 2 in the Z direction.

The optical element of the present embodiment combines the functions of the deflection element and the optical filter by integrating the deflection element and the optical filter using the adhesive layer as described above. That is, in the optical element of the present embodiment, the light incident from the incident surface is deflected, and at least a part of the light from the ultraviolet region to the near infrared region is selectively blocked and emitted. Thus, according to the optical element of the present embodiment, it is possible to reduce the size of the imaging apparatus. Furthermore, since the relationship between the refractive indexes of the deflecting element, the adhesive layer, and the optical filter satisfies the expressions (1) and (2), the optical loss of the optical element of the present embodiment is small.

Hereinafter, the downsizing of the imaging apparatus will be described with reference to FIG. FIG. 2 shows a configuration example of an imaging apparatus 100 having an objective lens 5, an object-side prism 6, an imaging lens group 8 (comprising lenses 81, 82, and 83), a lens moving mechanism 7, an optical element 10, and a solid-state imaging element 4. It is.

Incident light from the Z direction taken into the objective lens 5 is deflected in the Y direction by the reflecting surface of the object side prism 6, passes through the imaging lens group 8, and enters the optical element 10. The light emitted from the optical element 10 enters the light receiving surface 41 of the solid-state image sensor 4 and is converted into an electrical signal.

Here, by using the optical element 10 including the object-side prism 6 and the deflecting element 1, the thickness of the imaging device 100 in the Z direction is reduced. In particular, the imaging lens group 8 can be thinned by moving a part of the imaging lens group 8 in the Y direction by using a lens moving mechanism 7 such as a stepping motor, thereby providing a zoom lens function and a focus adjustment function. As described above, when the optical element 10 is arranged and used immediately before the solid-state imaging element 4, the optical element 10 is arranged in the order of the deflecting element 1, the adhesive layer 3, and the optical filter 2 from the incident side as shown in FIG. It is preferable.

In FIG. 2, the optical element 10 is arranged so that incident light from the Y direction is deflected in the Z direction by the deflecting element 1 and emitted. In the imaging apparatus 100, the optical element 10 may be arranged so as to be rotated by 90 ° about the Y direction as a rotation axis, and thereby the incident light from the Y direction is deflected in the X direction and emitted. it can.

In the imaging lens system including the objective lens 5, the object side prism 6 and the imaging lens group 8 of the imaging apparatus 100, the F number changes according to the aperture stop diameter. The F number is related by F = 1 / (2 × NA) using the capture angle θ and the numerical aperture NA = sin θ, and the radiated light from the subject is captured by the solid-state imaging device 4 according to the F number. The brightness changes. The maximum capture angles θ _m for typical F = 1, 1.4, 2, 2.4 of the imaging lens system are 30 °, 21.1 °, 14.5 °, 10.4 °, respectively. . That is, light having an incident angle range of −θ _m to + θ _m is incident on the optical element 10 with respect to the optical axis on the incident surface 1a of the optical element 10.

Next, the deflecting element, the optical filter, and the adhesive layer, which are components in the optical element of the present invention, will be described below.

<Deflection element>
In FIG. 1, a right-angle prism is illustrated as the deflecting element 1. However, as the deflecting element in the optical element of the present invention, incident light is deflected and emitted, and the expression (2) is expressed in relation to the refractive index with the adhesive layer. As long as the element has a refractive index n _P that satisfies the above, it can be used without any particular limitation.

Specific examples of the deflection element include a diffraction element and a prism. Examples of the diffractive element include a blazed reflection diffraction grating and a volume hologram diffractive element having a saw-shaped cross section. Examples of the prism include a triangular prism and a free-form surface prism having a non-planar reflecting surface. The blazed reflective diffraction grating exhibits a function as a deflecting element having high + 1st order diffraction efficiency at a predetermined diffraction angle, for example, by adjusting the grating material and the blazed shape.

As the deflection element, a prism is preferable from the viewpoint of stably processing a high-precision optical reflecting surface, and a triangular prism is more preferable. Further, among the triangular prisms, the angle formed by the incident surface and the output surface is 90 ° in the cross section of the YZ plane, and the angle formed by the incident surface and the reflective surface (for example, indicated by α in FIG. 3). Further, it is more preferable that the angle between the reflecting surface and the exit surface (for example, indicated by β in FIG. 3) is in the range of 40 to 50 °, and the cross section of the YZ plane is an isosceles right triangle. A right angle prism with β = 45 ° is particularly preferred.

For the incident angle and the outgoing angle of light in the optical element will be described based on the relationship between the refractive index n _P of the deflection element. FIG. 3 is a schematic diagram showing the relationship between the incident angle θ ₀ and the outgoing angle θ of light in the optical element 10 shown in FIG. In FIG. 3, the deflection element 1 is a triangular prism having a YZ plane cross section with a right isosceles triangle and extending in the X direction, that is, a right angle prism (hereinafter, the deflection element 1 is also referred to as a right angle prism 1).

The angle between the incident surface 1a and the reflecting surface 1b of the right-angle prism 1 and the angle between the emitting surface 1c and the reflecting surface 1b are both 45 °. In FIG. 3, in order to generalize the triangular prism, the angle formed by the incident surface 1a and the reflecting surface 1b is denoted by α, and the angle formed by the emitting surface 1c and the reflecting surface 1b is denoted by β. . In the following description of the right-angle prism 1, when these angles are described as α and β, the description can be generalized to a triangular prism as it is.

In the YZ plane, the light incident at an incident angle theta ₀ to the incident surface 1a of the light of the rectangular prism 1 having a refractive index n _P is refracted by the internal prism propagates in refraction angle theta 'incident surface 1a, the reflection surface 1b is reached.

In the right-angle prism 1, the angle formed by the incident surface 1a and the reflecting surface 1b is α, and the incident angle to the reflecting surface 1b is (α−θ ′). In addition, the relationship of sin θ ₀ = n _P × sin θ ′ is satisfied by the Snell refraction law. Here, it is necessary to satisfy n _P × sin (α−θ ′) ≧ 1 in order for the incident light on the reflecting surface 1b to be deflected to the emitting surface 1c by total reflection. That is, the refractive index n _P of the right-angle prism 1, it is necessary to satisfy the following relation.

In addition, the setting where the incident angle condition of the total reflection light with the incident light of convergent or divergent light is severe is the condition of the incident angle θ _{0 in} the direction of FIG. 3 (θ ₀ > 0), and from the F number of the imaging lens used, The incident angle range of incident light is defined by sin θ ₀ = 1 / (2F).

In right-angle prism 1 of alpha = 45 °, shows a graph of the minimum value of the refractive index n _P for totally reflecting the light incident angle theta _m is the maximum capture angle in FIG. FIG. 4 shows that total reflection is possible if the region is above the straight line indicating the relationship between the incident angle θ _m and the refractive index n _P. As shown in FIG. 4, when θ _m = 10 ° (NA = 0.17, F = 2.9), n _P ≧ 1.60, θ _m = 15 ° (NA = 0.26, F = 1.9). ), N _P ≧ 1.69, θ _m = 20 ° (NA = 0.34, F = 1.5), n _P ≧ 1.79, θ _m = 25 ° (NA = 0.42, F = 1.2), n _P ≧ 1.89.

The light totally reflected by the reflection surface 1b of the right-angle prism 1 reaches the emission surface 1c. The angle formed by the exit surface 1c and the reflection surface 1b is β, and the incident angle to the exit surface 1c is (β−α + θ ′). Furthermore, the outgoing angle θ of the light that passes through the adhesive layer 3 and the optical filter 2 and is emitted from the outgoing surface 2b of the optical filter 2 to the atmosphere side is sinθ = n _P × sin (β−α + θ ′) according to Snell's refraction law. Become.

In the right angle prism 1 with α = β = 45 °, sin θ = sin θ ₀ , and the exit angle θ is equal to the incident angle θ ₀ .

Here, let us consider a total reflection prism (n _P = 1.50 to 1.98) in which the right-angle prism 1 has an incident angle θ _m = 5 to 30 ° as a maximum incident angle. The light totally reflected by the reflecting surface 1b has a refractive index n _G of the adhesive layer 3 described below in the range of 1.35 to 1.80 and a refractive index n _F of the optical filter 2 of 1.35 to 2.50. Then, there is no total reflection at the interface between the right-angle prism 1 and the adhesive layer 3 and at the interface between the adhesive layer 3 and the optical filter 2. The light is emitted to the air surface on the image sensor side.

In an optical element using a triangular prism, when the range of the incident angle θ ₀ of incident light does not satisfy the relationship of the refractive index n _P that is totally reflected by the reflecting surface of the prism, for example, it is incident at n _P = 1.50. When the angle θ ₀ is larger than 5 °, when n _P = 1.70 and the incident angle θ ₀ is larger than 16 °, or when n _P = 1.90 and the incident angle θ ₀ is larger than 27 °. However, light loss can be suppressed by forming a reflective layer on the reflective surface. Examples of the reflective layer include a metal film such as Ag or Al, a high refractive index dielectric film (hereinafter referred to as “high refractive index film”) and a low refractive index dielectric film (hereinafter referred to as “low refractive index”). A dielectric multilayer film or the like in which films are referred to may be used. In the prism having a reflective layer formed on the reflective surface, there is an advantage that an inexpensive prism material can be used as compared with the case of using a prism capable of total reflection on the reflective surface. On the other hand, the process of forming the reflective layer becomes a load, and the reflectance is less than 100%, which is disadvantageous in terms of productivity and performance. The deflecting element 1 includes a configuration including a prism and a reflective layer.

Deflecting element is made of a material having a refractive index n _P satisfying formula (2) in relation to the refractive index of the adhesive layer. Refractive index _{n P} of the material used for the deflection element, depending on the type of the deflection element, preferably 1.4 to 2.5. When the deflecting element is a prism, the refractive index n _P is preferably 1.70 or more, more preferably 1.75 or more, and 1.80 or more from the viewpoint that the larger the maximum capture angle, the smaller the F-number bright imaging lens. Is more preferable.

When a right-angle prism is used as the deflecting element, as described above, a reflective layer may be provided on the reflective surface when n _P is 1.55 or less and the maximum incident angle θ _m is 8 ° or more. Even when a reflective layer is provided, the refractive index n _P is the refractive index of the prism material. In order to allow total reflection at a maximum incident angle θ _m with a right angle prism, θ _m = 8 ° and n _P is preferably more than 1.55, θ _m = 10 ° and n _P is preferably 1.60 or more, _{n P} is preferably 1.69 or more θ _m = 15 °, _{n P} is preferably 1.79 or more θ _m = 20 °, _{n P} by θ _m = 25 ° is preferably 1.89 or more. The upper limit of n _P is composition, from the viewpoint of the difference between the refractive index _{n G} of the adhesive layer can be 0.5 or less, 2.1 is preferred, 2.0 is more preferable.

As the material for the deflection element, glass having the n _P, resin and the like, glass being preferred. Examples of the glass having 1.70 ≦ n _P <1.80 include J-LASF014 (n _P = 1.7879), J-LASF016 (n _P = 1.7724), J-LAK09 (n _P = 1.7339), J-LAK18 (n _P = 1.7290), J-LAK10 (n _P = 1.7199), manufactured by OHARA, S-LAH66 (n _P = 1.772), S-YGH51 ( n _P = 1.755), include _{S-LAL19 (n P = 1.729} ) and the like.

Examples of the glass having 1.80 ≦ n _P <1.90 include J-LASFH22 (n _P = 1.88483), J-LASF05 (n _P = 1.8346), J-LASF09 (n _P = 1.8158), J-LASF015 (n _P = 1.8038), manufactured by Ohara, S-LAH92 (n _P = 1.892), S-LAH58 (n _P = 1.883), S-LAH89 ( _{n P = 1.851), S-} LAH55VS (n P = 1.835), S-LAH53V (n P = 1.806), S-LAH65VS (n P = 1.804), HOYA Corporation, TAFD30 ( n _P = 1.883), TAFD5F (n _P = 1.835), TAFD5G (n _P = 1.835), TAF3 (n _P = 1.804) and the like.

As glass of 1.90 ≦ n _P , J-LASFH21 (n _P = 1.9535), J-LASFH9 (n _P = 1.9024) manufactured by Hikari Glass Co., Ltd., S-LAH88 (n _P = 1.916), HOYA _{Corporation, TAFD45 (n P = 1.954)} , TAFD35 (n P = 1.911), TAFD25 (n P = 1.904), TAFD37 (n P = 1.900), _{TAFD55 (n P = 2.001),} FDS18-W (n P = 1.946), E-FDS1-W (n P = 1.923) , and the like.

Moreover, the deflection element, in addition to the refractive index n _P, depending on the type of adhesive layer and the optical filter, there are cases where UV permeability is required. For example, when the adhesive layer described below includes an ultraviolet curable material obtained by using an ultraviolet curable material, and the optical filter has a function of blocking UV, the deflecting element has UV transparency. It is good to have. In this specification, the light transmission of the deflection element refers to the light transmission in the relationship between the incident light and the light that is deflected and emitted after the incidence.

The wavelength of UV for which the deflection element is required to transmit is generally in the range of 250 to 400 nm depending on the ultraviolet curable material used for the adhesive layer. For curing the ultraviolet curable material, in particular, a wavelength in the vicinity of i-line (365 nm) where the emission intensity of the HgXe discharge lamp is high is preferably used. Considering this, in the above case, the maximum transmittance at a wavelength of 340 to 390 nm is preferably 10% or more, and more preferably 50% or more. In particular, the transmittance of the deflecting element with respect to 365 nm light is preferably 5% or more, more preferably 20% or more, and further preferably 50% or more. Higher transmittance is more advantageous for shortening the UV irradiation time, preferably 70% or more, and more preferably 80% or more.

Further, the deflection element may transmit visible light. Any of the glass of 1.70 ≦ n _P described above has an internal transmittance of UV wavelength 365 nm of 10% or more and an internal transmittance in the visible region of 420 nm to 700 nm of 92% or more. Can be used as material.

In the optical element of this embodiment, when a triangular prism is used as a deflecting element, for example, in the triangular prism 1 shown in FIGS. 1 and 3, the three corners in the YZ cross section are right angles or acute angles, so that chipping is performed. And easily cause cracks. Therefore, it is preferable to chamfer these corners.

The triangular prism 11 used in the optical element of the present embodiment illustrated in FIG. 5 is obtained by chamfering the three corners in the YZ section of the right-angle prism 1 shown in FIG.

The triangular prism 11 includes a W1 surface having a width w1 at a corner where the incident surface 1a and the reflecting surface 1b intersect, a W2 surface having a width w2 at a corner where the reflecting surface 1b and the emitting surface 1c intersect, and the incident surface 1a. And the exit surface 1c intersect at a corner (vertical angle = 90 °) has a C-plane with a width c. The W1 surface, the W2 surface, and the C surface are chamfered portions. Thus, the occurrence of chipping and cracks can be reduced by having a chamfered portion obtained by chamfering the corner portion.

The chamfering process is performed within a range where the signal light effective width Φin of the incident surface 1a of the triangular prism 11 and the signal light effective width Φout of the output surface 1c can be secured.

In the optical element of this embodiment regardless of the presence or absence of a chamfered portion, the reflected light path deviation angle on the reflecting surface is larger than the refracted optical path deviation angle on the transmission refracting surface having the same inclination angle deviation, and thus is required for the reflecting surface. The surface accuracy is about 2 to 4 times that of the transmission refractive surface. Therefore, the flatness of the reflecting surface 1b of the triangular prism 11 is related to the wavefront aberration that affects the resolution of the imaging device, and the rigidity of the prism material used, the film formation stress on the light incident surface 1a, and the light exit surface 1c, and bonding. Depends on the adhesive layer.

That is, an antireflection layer or a reflection layer may be formed on the incident surface 1a and the exit surface 1c of the triangular prism 11 as described later, and film stress is generated at that time. Further, when the optical filter 2 is integrated with the entrance surface 1a and the exit surface 1c via the adhesive layer 3, the difference in thermal expansion coefficient (when a thermosetting material is used for forming the adhesive layer) or polymerization shrinkage Residual stress is generated due to (when a thermosetting material or a photocurable material is used for forming the adhesive layer). Due to the influence of these stresses, if the chamfer widths w1 and w2 are narrow, the flatness of the end portion of the reflecting surface 1b of the triangular prism 11 may not be ensured. When such an optical element using the triangular prism 11 is used in, for example, an imaging apparatus as shown in FIG. 2, there is a possibility that the aberration of the imaging lens system is deteriorated and the resolution of the imaging apparatus is lowered. .

From the above viewpoint, the chamfering widths w1 and w2 at the chamfered portion are preferably independently 0.1 mm or more, and more preferably 0.2 mm or more. When the chamfer widths w1 and w2 are increased, the triangular prism 11 and the entire optical element using the prism prism 11 are increased in size. Therefore, the chamfer widths w1 and w2 are preferably independently 0.4 mm or less. The chamfer width c is preferably about 0.05 to 0.2 mm.

The W1 surface, W2 surface, and C surface, which are the chamfered portions shown in FIG. 5, are preferably diffusing surfaces that prevent light incident on this surface from becoming stray light, similarly to the side surfaces of the deflecting element described later. Further, it is more preferable that a light absorption / shielding film is provided on these surfaces.

<Adhesive layer>
In the optical element 10, the adhesive layer 3 is provided between the deflection element 1 and the optical filter 2 and has a function of bonding and integrating the two. The adhesive layer 3 is transparent to light having a predetermined wavelength to be transmitted by the optical element 10, for example, light in a wavelength range that the solid-state imaging device receives as signal light, and has an expression in relation to the refractive index with the optical filter 2. Any adhesive layer having a refractive index n _G that satisfies (1) and satisfies the formula (2) in relation to the refractive index with the deflecting element 1 can be used without particular limitation.

The constituent material of the adhesive layer preferably includes a thermosetting material or a photo-curing material. As the photocurable material, an ultraviolet curable material is preferable. For the formation of an adhesive layer containing a thermosetting material or a photo-curing material, a thermosetting material or a photo-curing material that fixes and solidifies by polymerization by heating or irradiation with light such as ultraviolet rays, in other words, is used. Can be used. Compared with the thermosetting material, the photocurable material completes the polymerization and solidification in a short time and has high productivity. Furthermore, the photo-curable material is advantageous when a member having low heat resistance is included because other members constituting the optical element are not easily affected by heat during curing.

As the photocurable material, an ultraviolet curable material is preferable, and when an ultraviolet curable material is used, it is preferable to add a photopolymerization initiator. The light irradiation wavelength and the polymerization sensitivity for the ultraviolet curable material depend on the type of the ultraviolet curable material or the type of the photopolymerization initiator. When an ultraviolet curable material is used, light in the wavelength range of 250 to 400 nm is used as irradiation light, and light in the vicinity of i-line (365 nm) where the emission intensity of the HgXe discharge lamp is high is often used.

As the thermosetting material, for example, EPO-TEK epoxy resin, # 301, # 301-2, # 310M-1, etc. can be used. Examples of the photocurable material include, for example, an ultraviolet curable material, a mercaptoester resin from Norland-Products, an epoxy resin from NOA60 series and NTT-AT, AT3925M, 3727E, an acrylate resin, # 18165, # 6205. Etc. can be used.

The adhesive layer 3 is a layer containing a cured material obtained by curing a curable material that is cured by light and / or heat. If necessary, the adhesive layer 3 is within a range that does not impair the effects of the present invention, and various additives made of non-cured materials in addition to the cured material, for example, UV absorbers, NIR absorbers and other absorbents, polymerization initiators, A polymerization inhibitor may be included.

Refractive index n _G of the adhesive layer 3 satisfies the formula (1) in relation to the refractive index of the optical filter 2, and the refractive index of the relationship between the deflection element 1 satisfying the formula (2) refractive index n _G It is. The refractive index n _G of the adhesive layer 3 depends on the deflecting element 1 and the optical filter 2 to be combined, but specifically, it is preferably 1.35 to 1.80, more preferably 1.45 to 1.65. If n _G is 1.35 or more, it is preferable in that the thickest member included in the optical filter 2 can use inexpensive and abundant kinds of materials with a refractive index n _F , and if it is 1.80 or less, the refractive index n. _{Since the} difference in refractive index between _P and refractive index n _F can be suppressed, it is preferable in that Fresnel reflection at each interface is small.

The adhesive layer 3 is transparent to light of a predetermined wavelength that the optical element 10 should transmit. Although it depends on the optical device in which the optical element is used, it is generally preferable that it exhibits high transparency to at least visible light. The thickness of the adhesive layer 3 is preferably 1 to 20 μm and more preferably 2 to 10 μm from the viewpoint of transparency, adhesive strength, productivity, and the like.

When an ultraviolet curable material is used as the adhesive layer 3 for joining the deflecting element 1 and the optical filter 2, the deflecting element 1 or the optical filter 2 needs to be a material that transmits UV for the following manufacturing reasons. . For example, when manufacturing the optical element 10 of FIG. 1, first, the optical element in which the adhesive layer 3 in the optical element 10 is a layer made of an adhesive layer forming composition containing an ultraviolet curable material for obtaining the adhesive layer 3. A precursor is prepared. Next, the UV curable material in the layer made of the composition for forming the adhesive layer is cured by irradiating UV from the deflecting element 1 side or the optical filter 2 side of the optical element precursor to form the adhesive layer 3.

When UV blocking properties are required for the optical element of the present invention, a UV reflecting layer is formed on the deflecting element 1, a UV absorber containing layer or a UV reflecting layer is formed on the optical filter 2, and the like. In such an optical element, when an adhesive layer is formed using an ultraviolet curable material, the adhesive layer can receive UV incident from the deflecting element side of the optical element or incident from the optical filter side of the optical element. The optical element is configured so as to be able to receive UV.

As long as a sufficient amount of UV reaches the adhesive layer to cure the ultraviolet curable material, there may be a member having UV blocking properties on both the deflection element side and the optical filter side of the adhesive layer. It is preferable that no member having UV blocking properties be present on one side, and a configuration in which a sufficient amount of UV can reach the adhesive layer from the deflecting element side is preferable. The value described for the deflection element can be applied to the UV transmittance of the deflection element or the optical filter.

<Optical filter>
The optical filter in the optical element of the present invention is an optical filter that selectively blocks light in at least a part of the region from the ultraviolet region to the near infrared region, and the refractive index n _{F of the} thickest member included in the optical filter. Can satisfy the expression (1) in relation to the refractive index n _G of the adhesive layer, and can be used without particular limitation.

Examples of the optical filter include an optical filter that selectively blocks both (i) UV and (ii) light in at least a part of the region from the visible region to the near infrared region. When combining the optical filter and the adhesive layer containing an ultraviolet curable material, as described above, the deflecting element preferably has UV transparency. Specifically, the maximum transmittance at a wavelength of 340 to 390 nm is 10% or more. Preferably there is.

Specific examples of such optical filters include (i) UV and (ii-1) blocking NIR and transmitting visible light, and (i) UV and (ii-2) blocking visible light. And an NIR transmission filter that transmits NIR. Further, (i) UV and (ii-3) block light in the first region in the near infrared region, and visible light and light in the second region on the longer wavelength side than the first region in the near infrared region. A band-pass filter that transmits light is also included.

These optical filters have (i) UV blocking properties such as, for example, blocking properties with an average UV transmittance of 300 to 400 nm being preferably 10% or less, and more preferably 2% or less.

(Ii-1) The NIR blocking property of the NIR cut filter is preferably a blocking property such that the average transmittance of NIR having a wavelength of 700 to 1100 nm is 5% or less, and more preferably 2% or less. As the visible light transmittance in the NIR cut filter, for example, the average transmittance of visible light having a wavelength of 440 to 620 nm is preferably 80% or more, and more preferably 90% or more.

(Ii-2) The visible light blocking property of the NIR transmission filter is preferably, for example, a blocking property in which the average transmittance of visible light having a wavelength of 400 to 730 nm is 5% or less, and more preferably 2% or less. . As the NIR transmittance in the NIR transmission filter, for example, it is preferable that the NIR wavelength has a continuous wavelength region of 40 nm or more with a transmittance of 80% or more between NIR wavelengths of 800 to 1000 nm, and preferably has a wavelength region of 80 nm or more.

For example, (ii-3) the blocking property of blocking the light in the first region in the near-infrared region of the band-pass filter has a second wavelength which is longer than the first region at the NIR wavelength of 700 to 1100 nm. The average transmittance of NIR in the first region excluding the continuous transmission wavelength band in the region is preferably 5% or less, and more preferably 2% or less. As the NIR transmittance of the second region on the longer wavelength side of the first region in the band pass filter, for example, continuous 40 nm or more and 80 nm with a transmittance of 80% or more between NIR wavelengths 800 to 1000 nm. It may have the following wavelength range, and preferably has a wavelength range of 40 nm or more and 60 nm or less. The visible light transmittance in the band-pass filter is preferably the same visible light transmittance as (ii-1).

6A to 6C, which are specific structures of the optical filter having selective light blocking properties, are YZ cross-sectional views respectively showing the optical filters 2A, 2B, and 2C used in the optical element of the present embodiment. The optical filters 2A, 2B and 2C can be used in place of the optical filter 2 of the optical element 10 shown in FIG. 1, for example. In the optical filters 2A, 2B and 2C, the left side shows the incident surface 2a in contact with the adhesive layer 3, and the right side shows the outgoing surface 2b in contact with the atmosphere.

The optical filter 2A shown in FIG. The shape of the absorption-type substrate 21 is a parallel plate shape having a pair of main surfaces facing each other, and light is blocked by absorption. In the optical filter 2 </ b> A, the thickest member included in the optical filter is the absorption substrate 21, and the refractive index n _F of the optical filter 2 </ b> A is the refractive index of the absorption substrate 21.

Examples of the absorbing substrate 21 include an absorbing glass substrate or a resin substrate containing a resin and an absorbing dye (hereinafter referred to as “absorbing resin substrate”). The thickness of the absorption substrate 21 is preferably 20 μm or more, although it depends on the configuration. In the case of an absorption type glass substrate, the thickness is preferably 50 to 500 μm, and in the case of an absorption type resin substrate, the thickness is preferably 20 to 200 μm.

The absorption glass substrate is obtained by forming absorption glass into a parallel plate shape. Examples of the absorption type glass include fluorophosphate glass containing CuO, phosphate glass containing CuO, and the like. Hereinafter, the fluorophosphate glass containing CuO and the phosphate glass containing CuO are collectively referred to as “CuO-containing glass”.

CuO-containing glass typically has an ability to absorb NIR having a wavelength of 700 to 1100 nm. In the CuO-containing glass, the absorption ability in the near infrared region can be adjusted by adjusting the CuO content and thickness.

In addition, for example, CuO-containing glass containing one or more of Fe ₂ O ₃ , MoO ₃ , WO ₃ , CeO ₂ , Sb ₂ O ₃ , V ₂ O _5, etc. is a short wavelength side in the ultraviolet region, For example, it has an absorption characteristic at a wavelength of 300 nm or less. The refractive index of the absorption type glass substrate is preferably 1.40 to 1.75, more preferably 1.45 to 1.60, as the refractive index of the CuO-containing glass.

The absorbing resin substrate is a substrate in which the absorbing dye is uniformly dissolved or dispersed in the resin. The resin is a matrix component for forming a parallel plate shape, and a transparent resin is preferable. As the absorbing dye, a dye that selectively absorbs light having a cutoff wavelength required for the optical filter 2 is used. Specific examples include a dye that selectively absorbs light in at least a part of the region from the ultraviolet region to the near infrared region, and a UV absorbing dye that selectively absorbs light in the wavelength region corresponding to the above (i). And any one of the absorbing dyes that selectively absorb light in the wavelength regions corresponding to the above (ii-1), (ii-2), and (ii-3), respectively.

In the absorption type resin substrate, the absorption wavelength band and the light absorption characteristics can be adjusted by selecting the absorption dye and adjusting the concentration and thickness. The refractive index of the absorptive resin substrate depends on the refractive index of the resin that is the matrix component. The refractive index of the absorptive resin substrate is preferably 1.35 to 1.75, more preferably 1.45 to 1.60.

The optical filter 2B shown in FIG. 6B includes a parallel plate-shaped substrate 21B having a pair of opposing main surfaces, and an absorption layer 22 formed on one main surface of the substrate 21B. In the optical filter 2B, the main surface that is not in contact with the absorption layer 22 of the substrate 21B is the incident surface 2a that is in contact with the adhesive layer 3, and the main surface that is not in contact with the substrate 21B of the absorption layer 22 is the emission surface 2b that is in contact with the atmosphere. .

That is, in the optical filter 2B, the absorption layer 22 is formed on the main surface opposite to the adhesive layer 3 side of the substrate 21B. The optical filter 2 used in the optical element 10 may have a configuration having the absorption layer 22 on the adhesive layer 3 side of the substrate 21B. However, the absorbing layer 22 is formed on the main surface opposite to the adhesive layer 3 side of the substrate 21B from the viewpoint that the closer to the light receiving surface of the solid-state imaging device, the reflected light tends to be stray light that affects image quality degradation. The optical filter 2B is preferable.

The substrate 21B may be the same absorption substrate as the absorption substrate 21 in the optical filter 2A, or may be a transparent substrate having no absorption from the ultraviolet region to the near infrared region. Examples of the transparent substrate include transparent glass, crystal such as crystal, lithium niobate, and sapphire, chemically tempered glass obtained by chemically strengthening soda lime glass, crystallized glass, or a substrate made of a transparent resin. These thicknesses can be the same as those of the absorption glass substrate and the absorption resin substrate, respectively. The absorption layer 22 has a thickness of about 1 to 50 μm as described below, and is thinner than the substrate 21B. Therefore, in the optical filter 2B, the thickest member included in the optical filter is the substrate 21B. The refractive index n _F of the optical filter 2B is the refractive index of the substrate 21B.

When the substrate 21B is made of glass, the refractive index of the substrate 21B is preferably 1.40 to 1.75, and preferably 1.45 to 1.60, as in the case where the absorption substrate 21 is an absorption glass substrate. When the substrate 21B is a transparent resin substrate or an absorption resin substrate, it is preferably 1.35 to 1.75, and preferably 1.45 to 1.60, as in the case where the absorption substrate 21 is an absorption resin substrate.

The absorbing layer 22 is a layer in which the absorbing dye is uniformly dissolved or dispersed in the resin. The resin and the absorbing dye can be the same as those of the absorbing resin substrate. Since the absorption layer 22 can be formed on the substrate 21B by a method such as wet coating, for example, the absorption layer 22 can be thinned, whereas the absorption resin substrate maintains its shape by itself and has a corresponding thickness. Is different. The absorption layer 22 is thinner than the substrate 21B, preferably 1 to 50 μm, more preferably 2 to 20 μm.

The resin used for the absorption layer 22 is preferably a transparent resin. Examples of the absorbing dye include a dye that can selectively absorb at least a part of light ranging from the ultraviolet region to the near infrared region when the absorption layer 22 containing the substrate and the substrate 21B are combined to form the optical filter 2B. .

Specifically, a UV-absorbing dye that selectively absorbs light in a wavelength region corresponding to (i) above, and a wavelength region corresponding to each of (ii-1), (ii-2), and (ii-3) above Absorption dyes that selectively absorb the light. As the absorption dye, when the absorption layer 22 and the substrate 21B are combined into the optical filter 2B, the absorption dye that can exhibit the absorption and transmission characteristics of the NIR cut filter, the NIR transmission filter, or the band transmission filter is used alone. Or a combination of two or more. When two or more kinds of absorbing dyes are used, a plurality of absorbing layers containing different absorbing dyes may be sequentially formed on the substrate 21B to form the laminated absorbing layer 22.

An optical filter 2C shown in FIG. 6C is formed on a parallel plate-shaped substrate 21C having a pair of main surfaces facing each other, an absorption layer 22 formed on one main surface of the substrate 21C, and the other main surface. The reflective layer 23 is made of. In the optical filter 2C, the main surface that is not in contact with the substrate 21C of the reflective layer 23 is the incident surface 2a that is in contact with the adhesive layer 3, and the main surface that is not in contact with the substrate 21C of the absorption layer 22 is the emission surface 2b that is in contact with the atmosphere. .

That is, in the optical filter 2C, the reflective layer 23 is formed on the main surface of the substrate 21C on the adhesive layer 3 side, and the absorption layer 22 is formed on the main surface on the opposite side. The optical filter 2 used in the optical element 10 may have a configuration in which the absorption layer 22 is provided on the adhesive layer 3 side of the substrate 21C and the reflection layer 23 is provided on the opposite side. Further, the optical filter 2 may have a configuration in which the absorption layer 22 and the reflective layer 23 are laminated in that order on the main surface of the substrate 21C on the adhesive layer 3 side or on the main surface on the opposite side. However, from the viewpoint that the layer closer to the light-receiving surface of the solid-state imaging device is more likely to have stray light that affects the image quality degradation, the substrate 21C has the reflective layer 23 on the adhesive layer 3 side, and the opposite side is the absorbing layer 22. The optical filter 2C having

The substrate 21C can be the same as the substrate 21B in the optical filter 2B. When the absorption layer 22 is the optical filter 2C, except that the absorption dye to be used is appropriately selected so that the blocking characteristics required for the optical filter 2 can be obtained together with the absorption characteristics of the substrate 21C and the reflection characteristics of the reflection layer 23. The same as the absorption layer 22 in the optical filter 2B. Since the thickness of the reflective layer 23 is about 1 to 10 μm as follows, in the optical filter 2C, the thickest member included in the optical filter is the substrate 21C. The refractive index n _F of the optical filter 2C is the refractive index of the substrate 21C.

The reflection layer 23 is a layer having a reflection wavelength band that selectively reflects light in at least a part of the region from the ultraviolet region to the near infrared region. The reflective layer 23 preferably has a reflection characteristic that exhibits the absorption transmission characteristic of the NIR cut filter, the NIR transmission filter, or the band transmission filter by functioning in a complementary manner with the substrate 21 </ b> C and the absorption layer 22.

The reflective layer 23 preferably has a reflection characteristic that blocks a part of light in the ultraviolet region. In that case, it is preferable to have UV blocking properties such that the average transmittance at a wavelength of 350 to 400 nm is 10% or less, and preferably 2% or less.

The reflective layer 23 is preferably composed of a dielectric multilayer film in which low refractive index films and high refractive index films are alternately laminated. The dielectric multilayer film may be configured to include a metal film as necessary.

The dielectric multilayer film is designed by using a conventionally known method for the specific number of layers and film thickness, and the refractive index of the high refractive index material and low refractive index material to be used according to the required optical characteristics. Can be manufactured. When the reflective layer 23 is a dielectric multilayer film, the total film thickness is preferably 1 to 10 μm, and more preferably 2 to 6 μm.

Various members such as an absorption type glass substrate, an absorption type resin substrate, a transparent substrate, an absorption layer, a reflection layer, and constituent materials included in the configuration of the optical filters 2A, 2B, and 2C and the constituent materials thereof are, for example, Is exemplified.

As described above, the example of the optical filter 2 has been described with reference to FIGS. 6A to 6C. However, the optical filter 2 is not limited to the configuration of the optical filters 2A, 2B, and 2C, and may be configured according to the gist of the present invention. It can be changed as appropriate. For example, the optical filter 2 may be composed of the substrate 21B and the reflective layer 23 formed on one or both of the main surfaces thereof. In the optical filter 2 including the substrate 21B and the absorption layer 22, the absorption layer 22 may be formed on both main surfaces of the substrate 21B.

<Relationship between refractive index n _P , refractive index n _G and refractive index n _F >
The relationship between the refractive index of the deflecting element, the adhesive layer, and the optical filter in the optical element of the present invention, that is, the relationship between the refractive index n _P , the refractive index n _G, and the refractive index n _F will be described. The reflectivity R [%] of the reflected light generated at the optical interfaces having different refractive indexes n1 and n2 can be approximated by the following equation when the incident angle is 30 ° or less from the Fresnel reflection law.

R = | n1-n2 | ² / (n1 + n2) ²
That is, if Δn = | n1-n2 |, R = Δn ² / (n1 + n2) ² , R> 0.09 / (n1 + n2) ² when Δn> 0.3, and R> 0 when Δn> 0.2. 0.04 / (n1 + n2) ² and Δn> 0.1, R> 0.01 / (n1 + n2) ² .

Expression is defined in the optical element of the present invention (1) is a graph showing the relation between the refractive index n _F the refractive index n _G, Equation (2) shows the relationship between refractive index n _G and the refractive index n _P. The refractive index _{n F} the refractive index _{n G} can be replaced by n1 and n2, the refractive index _{n P} and the refractive index _{n G} can be replaced by n1 and n2.

In the optical element of the present invention, n _G + n _F and n _P + n _G are required to be 2.6 or more from the viewpoint of an actual optical material having a transmission wavelength region within a wavelength range of 350 to 1100 nm. FIG. 7 shows the result of calculating the reflectance R [%] by adapting this to n1 + n2. FIG. 7 is a graph showing the relationship between the refractive index sum (n1 + n2) and the reflectance R [%] at optical interfaces having different refractive indexes (n1, n2).

From FIG. 7, when (n1 + n2) ≧ 2.6, R ≦ 3.70% when Δn = 0.5, R ≦ 2.37% when Δn = 0.4, and R ≦ 1. It can be seen that when 33% and Δn = 0.2, R ≦ 0.59%, and when Δn = 0.1, R ≦ 0.15%.

By satisfying Expression (1), that is, Δn _GF = | n _G −n _F | ≦ 0.5, the reflectance of Fresnel reflected light generated at the interface between the adhesive layer and the optical filter can be reduced to 3.70% or less. . Similarly, by satisfying Expression (2), that is, Δn _PG = | n _P −n _G | ≦ 0.5, the reflectance of Fresnel reflected light generated at the interface between the deflecting element and the adhesive layer is reduced to 3.70% or less. it can.

That is, the reflectance of reflected light generated at the interface between an optical material having a refractive index n1 = 1.5 or more and air having a refractive index n2 = 1.0 is 4% or more, but the refractive index n _P of the deflecting element and the optical filter. and to n _F, by using an adhesive layer having a refractive index n _G satisfying the relation of formula (1) and (2), the reflectance of each surface can be below 3.7%.

From the viewpoint of keeping the reflectance of Fresnel reflected light low, Δn _GF and Δn _PG are preferably 0.3 or less, more preferably 0.2 or less, and particularly preferably 0.1 or less. When Δn _GF is 0.2 to 0.5 and the interface reflectance is 1% or more, an antireflection layer may be formed at the interface between the adhesive layer and the optical filter in order to reduce Fresnel reflection. [Delta] n _PG may form an anti-reflection layer at the interface of the adhesive layer and likewise deflecting element in the case of 0.2-0.5. Since it is difficult to form the antireflection layer on the adhesive layer, the antireflection layer is preferably formed on the surface in contact with the adhesive layer of the optical filter or the surface in contact with the adhesive layer of the deflection element.

The relational expression of the reflectance R is for the case of normal incidence, but if the incident angle is 30 ° or less, the difference from the reflectance for normal incidence is slight.

<Antireflection layer>
As described above, the optical element of the present invention has an antireflection layer at the interface between the deflecting element and the adhesive layer and at the interface between the adhesive layer and the optical filter under the refractive index relationship of the expressions (1) and (2). May be. Furthermore, the optical element may have an antireflection layer on a surface in contact with the atmosphere. An antireflection layer may be provided in one place among these, may be provided in two places, and may be provided in all the places. In particular, when the reflectance of the reflected light generated at these interfaces is 1% or more, it is preferable to form an antireflection layer to reduce the reflectance to 0.5% or less.

FIG. 8 is an example of an optical element further including an antireflection layer in the optical element of the present embodiment. An optical element 10A shown in FIG. 8 includes an antireflection layer on the incident surface 1a that is an interface with the air of the deflection element 1, in addition to the deflection element 1, the adhesive layer 3, and the optical filter 2 in the optical element 10 shown in FIG. 12a, the antireflection layer 12b on the exit surface 1c which is the interface in contact with the adhesive layer 3 of the deflecting element 1, the antireflection layer 13a on the entrance surface 2a which is the interface in contact with the adhesive layer 3 of the optical filter 2, and the air of the optical filter 2 The antireflection layer 13b is provided on the emission surface 2b which is the interface with the.

The antireflection layer 12a, taking into account the range of the incident angle of light, is designed in accordance with the refractive index n _P of the deflecting elements 1, a dielectric multilayer film formed by alternately laminating a low refractive index film and the high refractive index film An antireflective layer consisting of can be used.

Antireflection layer 12b is provided in accordance with the value of [Delta] n _PG. For example, when Δn _PG is 0.1 or less, as shown in FIG. 7, since the reflectance R ≦ 0.15%, the antireflection layer 12b may not be provided. Similarly, in the range of Δn _PG = 0.2 to 0.5, R ≧ 0.59% depending on the refractive index value. Therefore, the antireflection layer 12b is preferably provided. The antireflection layer 12b, an anti-reflection layer comprising a single layer dielectric film having a thickness d _c the refractive index n _c, specifically, by using the antireflection layer satisfies the following two formulas, deflection The reflectance R at the interface between the element 1 and the adhesive layer 3 can be reduced.

Here, λ _c corresponds to the center wavelength of the light required for the light emitted from the optical element 10A, for example, the center wavelength of the incident signal light detected by the solid-state image sensor 4 in the imaging apparatus 100 shown in FIG. Using the wavelength λ _S and the longest wavelength λ _L , it is defined as λ _c = 2 × λ _S × λ _L / (λ _S + λ _L ).

That is, the refractive index _{n c} of the anti-reflective layer 12b is adjusted to the range of 1.6-1.9, if it thickness _{d c} = _{λ c} / a (4 × _{n c)} according to the wavelength lambda _c, wavelength the R = 0% at lambda _c. Further, when the incident angle θ ₀ ≦ 30 °, the incident angle dependence of the reflectance R of the antireflection layer 12b is slight. In order to reduce the reflectance with respect to incident light in a wide wavelength range, the antireflection layer 12b may be a dielectric multilayer film in the same manner as the antireflection layer 12a.

The antireflection layer 13a is provided according to the value of Δn _{GF in} the same manner as the antireflection layer 12b is provided according to the value of Δn _PG . For example, when Δn _GF is 0.1 or less, the antireflection layer 13a may not be provided. In the range of Δn _PG = 0.2 to 0.5, R ≧ 1.0% depending on the refractive index value. An antireflection layer 13a may be provided. In that case, the antireflective layer 13a, like the anti-reflection layer 12b, the film thickness d antireflection layer or reflectance made of a single layer dielectric film _c R was designed to reduce the refractive index n _c An antireflection layer made of a dielectric multilayer film is used.

The antireflection layer 13b is formed to reduce reflection at the interface between the optical filter 2 and air. As the antireflection layer 13b, similarly to the antireflection layer 12a, a dielectric multilayer film in which low refractive index films and high refractive index films are alternately laminated may be used. In the optical element 10A shown in FIG. 8, the optical filter 2 may be, for example, the optical filter 2A, 2B, or 2C shown in FIGS. 6A to 6C. If the optical filter 2A, as an anti-reflection layer 13b, an anti-reflection layer including a dielectric multilayer film which is designed in accordance with the refractive index n _F of the absorption-type substrate 21 can be used. In the case of the optical filters 2B and 2C, an antireflection layer made of a dielectric multilayer film designed according to the refractive index of the absorption layer 22 can be used as the antireflection layer 13b.

<Reflective layer>
In the optical element of the present invention, the optical filter has a function of selectively blocking light in at least a part of the region from the ultraviolet region to the near infrared region. As described above, the optical filter selectively selects, for example, (i) UV and (ii-1) NIR, (ii-2) visible light, or (ii-3) light in the first region in the near infrared region. It has a function to shut off. The optical element of the present invention may have a configuration in which a part of the blocking performance is shared by other than the optical filter.

Specifically, a reflective layer that reflects light in a wavelength range selected from the above (i), (ii-1), (ii-2), and (ii-3) is, for example, an optical element 10A shown in FIG. Instead of the antireflection layer 12a or the antireflection layer 12b, the deflection element 1 may be provided on the incident surface 1a or the emission surface 1c. In that case, the optical filter 2 may have a configuration that does not have the light blocking property of the reflective layer provided on the deflection element 1. In this way, the optical element as a whole is designed to have a light transmission and blocking performance in a predetermined region.

<Light shielding film>
For example, when the optical element of the present invention is used in an imaging apparatus, there is a need to reduce stray light due to scattering and reflection from various optical members and holding members of the imaging apparatus. For the purpose of reducing the stray light, etc., the first light shielding film that partially blocks light incident on the optical element from the incident side and / or the second light shielding film that blocks light incident on the optical element from the side surface. May be further provided.

Note that the “light-shielding film” refers to a film that blocks at least visible light of incident light. The light shielding film preferably blocks light of all wavelengths from the ultraviolet region to the near infrared region. Specifically, the light shielding film may have a light transmittance of 10% or less at a wavelength of 350 to 1000 nm, and preferably 2% or less.

For example, in the imaging apparatus 100 shown in FIG. 2, an incident angle range of −θ ₀ to + θ ₀ defined according to the F number of the imaging lens system (objective lens 5, object-side prism 6 and imaging lens group 8). Light enters the optical element 10 and is deflected, and unnecessary light is blocked and emitted from the solid-state image sensor 4 and reaches the light receiving surface 41 of the solid-state image sensor 4 as signal light. Here, if reflected light generated on the surface of each optical member of the imaging lens system or light scattered on the wall surface of a housing (not shown) such as a lens holder becomes stray light and enters the optical element 10, the cause of image quality deterioration It becomes.

In order to block such stray light other than the signal light used in the solid-state imaging device 4 before entering the light-receiving surface 41 of the solid-state imaging device 4, the imaging apparatus 100 has a configuration other than the opening corresponding to the light-receiving surface 41. It is preferable to have a light shielding film in the region. When the light shielding film is formed on the optical element 10 on the side close to the light receiving surface 41 of the solid-state imaging element 4 in the imaging apparatus 100, it is effective in removing stray light.

The optical element 10 may have a first light shielding film that partially blocks light from the incident side of the optical element 10. The optical element 10 preferably has a second light shielding film that blocks light incident on the optical element 10 from the side surface. The optical element 10 may have both the first light shielding film and the second light shielding film.

9A, 9B, FIG. 10, FIG. 11, and FIG. 12 show a cross-sectional view, a plan view, and a perspective view, respectively, of optical elements 10B, 10C, 10D, and 10E having a light shielding film in the optical element of the present invention. Optical elements 10B, 10C, and 10D shown in FIGS. 9A, 9B, 10, and 11 include an optical element having a light shielding film 15 as a first light shielding film that partially blocks light incident from the incident side of the optical element. It is an example. An optical element 10E shown in FIG. 12 is an example of an optical element having a light shielding film 15B as a second light shielding film that blocks light incident from the side surface of the optical element.

9A shows an optical element 10B in which the light shielding film 15 is formed at the interface with the air of the optical filter 2 in the optical element 10 shown in FIG. 1, and FIG. 9B shows the optical element 10B viewed from the light shielding film 15 side. . In the optical element 10B, the deflection element 1, the adhesive layer 3, and the optical filter 2 can be the same as those of the optical element 10.

In the optical element 10B, the shape of the light shielding film 15 has a frame-like shape in which the outer periphery coincides with the outer periphery of the emission surface 2b of the optical filter 2 in the shape of the main surface. By making the light shielding film 15 into such a frame shape, for example, when the optical element 10B is arranged in place of the optical element 10 in the imaging device 100 shown in FIG. The central portion can secure a rectangular signal light emission region so as not to block the signal light, and can block only the incident light at the peripheral portion.

As the light shielding film 15, for example, a structure in which a metal film such as Cr and an antireflection layer such as CrOx that prevents surface reflection of the metal film are laminated, or a resin light shielding film containing a light absorber and a resin that exhibits light shielding properties. Etc. can be exemplified. Examples of the light absorber include inorganic or organic colorants such as carbon black and titanium black. Resin is a matrix component for forming a light shielding film. For example, the resin light-shielding film is formed on the emission surface 2b of the optical filter 2 by a printing method or a photolithography method using a light absorber and a photocurable material (resin).

In addition, the formation method of the light absorber, the photocurable material (resin), and also the light shielding film containing these in a resin light shielding film is illustrated by WO2014 / 021245A, for example.

The thickness of the light shielding film 15 is preferably about 50 to 500 nm in the case of a structure in which an antireflection layer is laminated, and is preferably about 0.1 to 400 μm in the case of a resin light shielding film. The thickness is more preferably 0.2 to 100 μm, and even more preferably 0.5 to 10 μm.

An optical element 10C shown in FIG. 10 is an example in which, in the optical element 10B shown in FIGS. 9A and 9B, the light shielding film 15 is provided on the incident surface 2a of the optical filter 2 instead of on the outgoing surface 2b of the optical filter 2. Further, the optical element 10D shown in FIG. 11 is an example in which the light shielding film 15 is provided on the incident surface 1a of the deflecting element 1 instead of on the outgoing surface 2b of the optical filter 2 in the optical element 10B shown in FIGS. 9A and 9B. is there.

The light shielding film 15 included in the optical element 10C and the optical element 10D can be the same as the light shielding film 15 included in the optical element 10B, except that the arrangement position is different. Each of the optical elements 10B, 10C, and 10D is an example in which the light shielding film 15 is provided on each surface on the emission surface 2b of the optical filter 2, the incident surface 2a of the optical filter 2, and the incident surface 1a of the deflection element 1. However, in order to further improve the light blocking property of stray light, these two surfaces (1a + 2a, 1a + 2b, 2a + 2b) or three surfaces (1a + 2a + 2b) may be formed.

An optical element 10E shown in FIG. 12 is an example having the light shielding film 15B over the entire area of both side surfaces of the deflection element 1 in the side surface of the optical element in the optical element 10 shown in FIG.

The deflection element 1 in the optical element 10 shown in FIG. 1 is a triangular prism, and has large areas on the side surfaces 1d and 1e perpendicular to the light incident / exit surfaces 1a and 1c. Therefore, when stray light entering the prism reaches the side surface, it may be reflected and transmitted through the light exit surface 1c and emitted from the optical element 10. In that case, for example, in the imaging apparatus 100 illustrated in FIG. 2, the ratio of stray light emitted from the optical element 10 to the light receiving surface 41 of the solid-state imaging element 4 is high. In particular, in the case of a triangular prism having a high refractive index, the light incident on the side surface 1d or 1e is totally reflected, and stray light reaching the light receiving surface 41 increases.

Therefore, by forming the light shielding film 15B over the entire area of both side surfaces 1d and 1e of the deflecting element 1 as in the optical element 10E, the reflected light itself from the side surfaces 1d and 1e can be sufficiently reflected, for example, in the regular reflectance ratio. The stray light emitted from the optical element 10 can be suppressed to a low level. The light shielding film 15B can have a configuration other than the shape, for example, a layer configuration, a constituent material, and a formation method, in the same manner as the light shielding film 15 included in the optical element 10B. In forming the light shielding film 15B, it is preferable to form the light shielding film 15B after making the side surfaces 1d and 1e have a non-flat diffusion surface, since substantial stray light is further reduced.

As a method of setting the side surfaces 1d and 1e as the diffusing surface, when the deflecting element 1 is processed into a triangular prism shape, cutting is performed using a cutting blade such that the side surfaces 1d and 1e become rough surfaces, or the side surface 1d after cutting. And 1e are lapped and polished to form a diffusion surface corresponding to a rating of # 1000 or less.

In the optical element 10, stray light emitted from the emission surface of the optical element can be reduced to some extent only by using the side surfaces 1 d and 1 e of the deflection element 1 as diffusion surfaces. That is, by making the side surfaces 1d and 1e of the deflecting element 1 diffusing surfaces, generation of total reflected light generated on the optical flat surface is suppressed (increased transmitted light to the air side), and incident light is diffused at a wide angle. Thus, for example, the amount of stray light that enters the light receiving surface 41 of the solid-state imaging device 4 as a bright spot can be reduced. In the optical element of the present invention, as described above, the side surfaces 1d and 1e of the deflecting element 1 are preferably formed with the light shielding film 15B after forming the diffusion surface.

<Modification of optical element>
In the optical element of the present embodiment described above, the size (outer edge) of the exit surface 1c of the deflection element 1 and the entrance / exit surfaces 2a and 2b of the optical filter 2 are substantially the same. In the optical element of the present invention, for example, the deflecting element may be a prism, and (I) on each surface where the prism and the optical filter face each other, the outer edge of the prism may be inside the outer edge of the optical filter. (II) In each surface where the prism and the optical filter face each other, the configuration may be such that the outer edge of the prism is outside the outer edge of the optical filter.

FIG. 13A shows an optical element 10F similar to the optical element 10B except for the configuration of (I) above in the optical element 10B shown in FIGS. 9A and 9B. FIG. 13B is a diagram of the optical element 10F viewed from the light shielding film 15 side.

In the optical element 10 </ b> F, the outer edge of the exit surface 1 c of the deflecting element 1 is inside the outer edges of the entrance / exit surfaces 2 a and 2 b of the optical filter 2. 13A and 13B, the length in the Y direction of the exit surface 1c of the deflection element 1 is L _p , the length in the X direction is W _p , and the length in the Y direction of the entrance and exit surfaces 2a and 2b of the optical filter 2 is L. _F, the length of X direction is indicated by _{W F,} and _L F> L _P, has been shown to be a _W F> W _P.

In the optical element 10F, the configuration (I) is advantageous in that the light shielding film 15 can be formed so as to surely include the outer periphery of the deflection element 1, and stray light can be reliably reduced.

FIG. 14A shows an optical element 10G similar to the optical element 10B except for the configuration of (II) above in the optical element 10B shown in FIGS. 9A and 9B. FIG. 14B is a diagram of the optical element 10G viewed from the light shielding film 15 side.

In the optical element 10G, the outer edge of the exit surface 1c of the deflecting element 1 is outside the outer edges of the entrance / exit surfaces 2a and 2b of the optical filter 2. 14A and 14B, the length in the Y direction of the exit surface 1c of the deflecting element 1 is L _p , the length in the X direction is W _p , and the length in the Y direction of the entrance and exit surfaces 2a and 2b of the optical filter 2 is L. _F, the length of X direction is indicated by _{W F,} and _L F <L _P, has been shown to be a _W F <W _P.

In the optical element 10G, due to the configuration of (II) above, the dimensional accuracy of the optical element compared to the case where the outer edge on the emission side of the optical element coincides with the outer edge of the deflecting element 1 and coincides with the outer edge of the optical filter 2. This is advantageous in that

The embodiments of the optical element of the present invention have been described above using the optical elements 10, 10A to 10G, but the optical element of the present invention is not limited to the above-described embodiment. These embodiments can be changed or modified without departing from the spirit and scope of the present invention.

[Production method]
Specifically, the production method of the present invention includes the following steps (A) and (B).
(A) A step of producing an optical element precursor having a composition layer for forming an adhesive layer containing an ultraviolet curable material between the deflecting element and the optical filter (here, the optical element precursor is an optical element to be manufactured). (It is the structure which has the composition layer for adhesive layer formation containing an ultraviolet curable material instead of an adhesive layer in the arrangement | positioning position of the adhesive layer of an element.)
(B) Curing the composition layer for forming the adhesive layer by irradiating the optical element precursor with light in the ultraviolet region from the incident side when the optical element is used or from the emission side when the optical element is used Process to make the adhesive layer

Hereinafter, each process of the manufacturing method of the present invention will be described by taking a method of manufacturing the optical element 10 shown in FIG. 1 as an example.

(A) Process (A) The process (A) is located between the deflection element 1 and the optical filter 2 located on the exit side of the deflection element 1 and between the deflection element 1 and the optical filter 2 and is cured by the following process (B). In this step, a precursor of the optical element 10 having the adhesive layer forming composition layer, which becomes the adhesive layer 3 for integrating the deflecting element 1 and the optical filter 2, is prepared.

The composition for forming an adhesive layer constituting the composition layer for forming an adhesive layer contains an ultraviolet curable material. The ultraviolet curable material is as described above. The composition for forming an adhesive layer preferably contains the above-described photopolymerization initiator and, if necessary, contains various additives. Further, in order to prevent the curable material from being polymerized and solidified by light, heat, air or the like during storage, a polymerization inhibitor may be mixed and used. The composition for forming an adhesive layer may further contain a solvent in order to ensure good coatability. The solvent is a component that is removed from the composition layer for forming an adhesive layer by drying or the like during the manufacturing process of the optical element.

In the preparation of the precursor of the optical element 10, an adhesive layer forming composition containing each of the above components is prepared so that the cured film thickness on the exit surface 1 c of the deflection element 1 becomes a desired thickness. The composition for forming an adhesive layer is uniformly applied to obtain the deflection element 1 with the composition layer for forming an adhesive layer. Next, the optical filter 2 is laminated on the composition layer for forming an adhesive layer so that the incident surface 2a of the optical filter 2 is in contact therewith. In addition, when the composition for forming the adhesive layer to be used contains a solvent, the solvent is dried and removed before the optical filter 2 is laminated.

In the above, the surface on which the composition for forming an adhesive layer is applied may be the incident surface 2a of the optical filter 2. In that case, the deflecting element 1 is laminated so that the exit surface 1c of the deflecting element 1 is in contact with the adhesive layer forming composition layer formed on the incident surface 2a of the optical filter 2. Similarly to the above, when the composition for forming an adhesive layer to be used contains a solvent, the solvent is dried and removed before the deflection element 1 is laminated. Thus, the precursor of the optical element 10 which has the composition layer for contact bonding layer formation instead of the contact bonding layer 3 in the optical element 10 is produced.

(B) Step About the precursor of the optical element 10 obtained in the step (A), UV is applied to the composition layer for forming the adhesive layer according to the curing conditions of the ultraviolet curable material contained in the composition for forming the adhesive layer. Irradiate. Thereby, an ultraviolet curable material hardens | cures and the optical element 10 which has the contact bonding layer 3 containing an ultraviolet curable material is obtained.

As a method of irradiating the composition layer for forming an adhesive layer with UV, the precursor of the optical element 10 is irradiated with UV from the incident surface 1a side of the deflecting element 1, or from the output surface 2b side of the optical filter 2. The method of irradiating UV is mentioned. When the reflecting surface 1b of the deflecting element 1 is a total reflecting surface and no reflecting material for blocking the UV incidence to the inside of the deflecting element 1 is formed, UV may be irradiated from the reflecting surface 1b side.

In addition, when the UV reflective layer is formed in the deflection | deviation element 1, or when the optical filter 2 has an absorption layer and reflective layer provided with the function which interrupts | blocks UV, the transmittance | permeability of UV used for photopolymerization hardening is high. It is preferable to perform UV irradiation from the side because productivity is improved. When the optical filter 2 has a function of blocking UV, the deflecting element 1 is configured to have UV transparency, and the composition for forming an adhesive layer is irradiated with UV from the incident surface 1a side or the reflecting surface 1b side of the deflecting element 1. The physical layer is an adhesive layer. Further, when a UV reflecting layer is formed on the deflecting element 1, the optical filter 2 is designed so as not to have UV blocking properties, and UV is irradiated from the emission surface 2b side of the optical filter 2 for forming an adhesive layer. The composition layer is an adhesive layer. In the production method of the present invention, the former is preferred.

According to the manufacturing method of the present invention described above, an optical element in which a deflection element and an optical filter are integrated by an adhesive layer can be easily manufactured by using UV irradiation.

Hereinafter, an example of manufacturing the optical element of the present invention will be described.
<Production example>
The traveling direction of the light incident from the incident surface of the deflecting element is deflected by the deflecting element, and then the light having the specific wavelength range of the incident light blocked by the optical filter integrated on the exit surface of the deflecting element using the adhesive layer An example of manufacturing the optical element of the present invention that emits from the exit surface of the optical filter will be described below with reference to FIGS.

The optical element 10H shown in a sectional view in FIG. 15 is similar to the deflection element 11 shown in FIG. 5, the optical filter 2C shown in FIG. 6C on the emission side of the deflection element 11, and the deflection element 11 and the optical filter 2C. There is an adhesive layer 3 between them. The optical element 10H has an antireflection layer 12a on the incident surface 1a of the deflection element 11, an antireflection layer 12b on the emission surface 1c of the deflection element 11, and an antireflection film 13b on the emission surface 2b of the optical filter 2C. The optical element 10H further includes, on the antireflection film 13b, a light shielding film 15 having a frame shape in which the outer periphery coincides with the outer periphery of the antireflection film 13b in the shape of the main surface. A light shielding film 15B similar to that shown in FIG. 12 is provided over the entire area on the two side surfaces 1d and 1e.

(Production of deflection element 11)
As the deflection element 11, the refractive index _{n P} at a wavelength of 589nm is 1.75 or more, the internal transmittance of a transparent and ultraviolet wavelengths 365nm in wavelength range 400 ~ 1100 nm is cutting a 10 percent or more optical glass triangular prism shape.

Here, the triangular prism prism cross section is an isosceles right triangle with an apex angle of 90 °. The light incident surface incident from the Y direction, the light output surface emitted in the Z direction, and the total reflection surface deflected from the Y direction to the Z direction are all polished into an optical mirror surface. Furthermore, C surface processing and Chamfering of W1 surface and W2 surface are performed, and each chamfering part is obtained. The width of the isosceles surface that is the light incident / exit surface of the triangular prism is processed to a dimension that covers the signal light effective width Φin of the light incident surface and the signal light effective width Φout of the light output surface. For the triangular prism, which is the deflecting element 11, J-LASFH21, an optical glass company having an internal transmittance of 26% with n _P = 1.954 and a wavelength of 365 nm of 10 mm is used.

Next, antireflection layers 12a and 12b are formed so as to cover the effective widths Φin and Φout of the air interface which is the light incident surface 1a of the triangular prism and the adhesive layer interface which is the light emitting surface 1c. The residual reflection in the signal light wavelength region is 0.5% or less.

Next, the triangular prism is cut into the element shape shown in FIG. 12 using a dicing device in parallel with the ZY plane so that the dimension in the X direction covers the light receiving surface of the solid-state imaging device, and the cut surfaces 1d and 1e are optically cut. The diffusion surface. In order to prevent the light incident from the cut surfaces 1d and 1e from becoming stray light, a light shielding film-forming composition containing a light absorber and an ultraviolet curable resin is further applied thereon, and a light shielding film 15B is formed by UV irradiation. Thus, the deflecting element 11 with a light shielding film is obtained.

(Preparation of optical filter 2C)
The optical filter 2C is a NIR cut filter that transmits visible light and blocks UV and NIR. For example, a filter function that blocks UV of 300 to 400 nm and NIR of 700 to 1100 nm and transmits visible light of 420 to 660 nm. Have

As the substrate 21C of the optical filter 2C, an NIR absorption type glass substrate 21C obtained by adding CuO or the like to a fluorophosphate glass is used. The thickest member in the optical filter 2C is the glass substrate 21C, and n _F ≈1.52. A reflective layer 23 made of a dielectric multilayer film having reflection wavelength bands of 350 to 400 nm and 700 to 1100 nm is formed on the interface of the optically polished NIR absorption glass substrate 21C on the adhesive layer 3 side. Further, an absorption layer 22 containing an NIR absorbing dye having an absorption maximum wavelength at 650 to 750 nm is formed at the air interface on the light emitting surface (solid-state imaging device) side of the NIR absorption type glass substrate 21C. The absorbing layer 22 optionally contains a UV absorbing dye.

The NIR absorption type glass substrate 21C has an absorption maximum wavelength in the vicinity of 900 nm. However, when it is attempted to increase the absorption of NIR, the NIR absorption type glass substrate absorbs visible light and causes a decrease in visible light transmittance. Therefore, the glass substrate thickness is adjusted so as to suppress a decrease in visible light transmittance. Similarly, the content of the NIR absorbing dye in the absorption layer 22 is adjusted so as to suppress a decrease in visible light transmittance. When the NIR absorption type glass substrate 21C and the absorption layer 22 are adjusted so as to suppress the decrease in the transmittance of visible light, the wavelength regions where transmitted light is generated are generated at 350 to 400 nm and 700 to 1100 nm. The reflective layer 23 having a wavelength band is designed.

Note that the refractive index n _F of the glass substrate 21C can be realized so that the reflective layer 23 having a small number of layers and a total film thickness can exhibit high transmittance in the visible range of 420 to 660 nm and low transmittance in the reflected wavelength range. A dielectric multilayer film is designed on the premise that the adhesive layer 3 having a refractive index n _G of 0.1 or less is used.

Here, in the reflection layer 23, the reflection wavelength band shifts to a short wavelength region as the incident angle of incident light increases, and the spectral transmittance of the entire optical filter 2C changes. The absorption layer 22 complements the NIR absorptivity of the NIR absorption type glass substrate 21C, and also has a role of reducing the incident angle dependency of such spectral characteristics.

Next, the antireflection layer 13b is formed on the air interface of the absorption layer 22 of the optical filter 2C, and the residual reflection with respect to the signal light wavelength region at the interface is 0.5% or less. Further, a frame-shaped light shielding film 15 is formed in a peripheral region other than the signal light transmission effective region at the air interface of the antireflection layer 13b to obtain an optical filter 2C with a light shielding film.

(Production of optical element by formation of adhesive layer 3)
Since the optical filter 2C with the light shielding film thus produced is bonded and fixed to the deflection element (triangular prism) 11 with the light shielding film produced as described above, the optical filter 2C is cured on the bonding surface of the deflection element (triangular prism) 11 or the optical filter 2C. A liquid adhesive layer-forming composition containing the previous ultraviolet curable material is applied to form an adhesive layer-forming composition layer, and a light-shielding film-attached deflection element 11 or a light-shielding film-attached optical filter 2C is laminated thereon. Thus, a precursor of the optical element is obtained. The thickness of the composition layer for forming the adhesive layer is adjusted so that the finally obtained adhesive layer 3 has a uniform thickness of 2 to 20 μm.

Next, UV is irradiated from the incident surface or / and the total reflection surface of the deflecting element (triangular prism) 11 to polymerize and solidify the ultraviolet curable material in the composition layer for forming the adhesive layer, whereby the adhesive layer 3 is obtained.

When an ultraviolet curable material is used as the adhesive layer 3, for example, in the case of Norland Products NOA61 having a refractive index n _G of 1.56 after curing, Δn _GF = | n _G −n _F | = 0.04, There is no antireflection layer at the interface between the adhesive layer 3 and the optical filter 2C. On the other hand, since Δn _PG = | n _P −n _G | = 0.394, an antireflection layer 12 b is provided at the interface between the deflection element (triangular prism) 11 and the adhesive layer 3.

Incidentally, in the optical element 10H, when the difference in refractive index n _P and the refractive index n _G is small, it provided the optical filter 2B shown in Figure 6B in place of the optical filter 2C the exit side of the deflecting element 11, deflection elements 11 In addition, the adhesive layer 3 may be provided between the optical filter 2B, the reflective layer 23 on the emission surface 1c of the deflection element 11, and the antireflection layer 12b. In that case, the antireflection layer 12a, the antireflection layer 13b, and the light shielding films 15 and 15B can be configured similarly to the optical element 10H.

The optical element of the present invention is an optical element having both a light deflection function and a selective blocking function. In an imaging apparatus such as a digital still camera using a solid-state image sensor, the optical element is disposed immediately before the light-receiving surface of the solid-state image sensor. If used, it is advantageous for downsizing of the imaging device.

10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H ... optical elements,
DESCRIPTION OF SYMBOLS 1,11 ... Deflection element 2, 2A, 2B, 2C ... Optical filter, 3 ... Adhesive layer,
21 ... Absorbing substrate, 21B, 21C ... Substrate, 22 ... Absorbing layer, 23 ... Reflecting layer,
12a, 12b, 13a, 13b ... antireflection layer, 15, 15B ... light shielding film,
DESCRIPTION OF SYMBOLS 4 ... Solid-state image sensor, 5 ... Objective lens, 6 ... Object side prism, 7 ... Lens moving mechanism, 8 ... Imaging lens group, 100 ... Imaging device.

Claims (20)

1. A deflection element that deflects and emits incident light; and
   An optical filter that selectively blocks light in at least a part of the region from the ultraviolet region to the near infrared region, which is located on the incident side or the emission side of the deflection element;
   An adhesive layer that integrates both between the deflection element and the optical filter;
   When the refractive index of the deflecting element is n _P , the refractive index of the adhesive layer is n _G , and the refractive index of the member having the largest layer thickness among the members included in the optical filter is n _F , the formula (1) And an optical element satisfying the relationship of the formula (2).
   Δn _GF = | n _G −n _F | ≦ 0.5 (1)
   Δn _PG = | n _P −n _G | ≦ 0.5 (2)
2. The optical element according to claim 1, wherein the deflection element is a prism.
3. The optical element according to claim 2, wherein the prism is a right angle prism.
4. Refractive index n _P of the prism optical element according to claim 2 or claim 3 1.70 or more.
5. 5. The optical element according to claim 1, wherein the adhesive layer includes an ultraviolet curable material.
6. The adhesive layer can receive ultraviolet light incident from the deflection element side of the optical element, or can receive ultraviolet light incident from the optical filter side of the optical element, The optical element according to claim 5, wherein in the optical element, ultraviolet light incident from the incident side of the deflecting element is not transmitted to the output side of the optical filter.
7. The optical filter blocks light in the ultraviolet region and selectively blocks light in at least a part of the range from the visible region to the near infrared region,
   The optical element according to claim 5 or 6, wherein the deflecting element has a maximum transmittance of light having a wavelength of 340 to 390 nm of 10% or more.
8. The optical element according to claim 7, wherein the optical filter is a near-infrared cut filter that transmits visible light and blocks near-infrared light.
9. The optical element according to any one of claims 1 to 8, wherein the member having the largest layer thickness in the optical filter is a glass substrate.
10. The optical element according to claim 9, wherein the glass substrate is made of a fluorophosphate glass containing CuO or a phosphate glass containing CuO.
11. The optical element according to claim 9 or 10, wherein the optical filter has an absorption layer containing a resin and an absorption pigment on at least one surface of the glass substrate.
12. The optical element according to any one of claims 1 to 8, wherein the member having the largest layer thickness in the optical filter is a resin substrate.
13. The optical element according to claim 12, wherein the resin substrate contains an absorbing dye.
14. The optical element according to claim 12 or 13, wherein the optical filter has an absorption layer containing a resin and an absorption pigment on at least one surface of the resin substrate.
15. The optical element according to any one of claims 9 to 14, wherein the optical filter includes a reflective layer made of a dielectric multilayer film that blocks light in a part of the ultraviolet region.
16. The optical element according to any one of claims 1 to 15, further comprising a first light-shielding film that partially blocks light incident on the optical element from an incident side.
17. The optical element according to any one of claims 1 to 16, further comprising a second light-shielding film that blocks light incident on the optical element from a side surface.
18. The optical element according to any one of claims 2 to 17, wherein an outer edge of the prism is on an inner side of an outer edge of the optical filter in each surface where the prism and the optical filter face each other.
19. The optical element according to any one of claims 2 to 17, wherein an outer edge of the prism is on an outer side than an outer edge of the optical filter on each surface where the prism and the optical filter face each other.
20. A deflection element that deflects and emits incident light; and an optical filter that selectively blocks light in at least a part of the range from the ultraviolet region to the near infrared region, which is located on the incident side or the emission side of the deflection element; An adhesive layer that integrates both between the deflection element and the optical filter;
    When the refractive index of the deflecting element is n _P , the refractive index of the adhesive layer is n _G , and the refractive index of the member having the largest layer thickness among the members included in the optical filter is n _F , Δn _GF = | A method of manufacturing an optical element that satisfies the relationship of n _G −n _F | ≦ 0.5 and Δn _PG = | n _P −n _G | ≦ 0.5,
    A step of producing an optical element precursor having a composition layer for forming an adhesive layer containing an ultraviolet curable material between the deflection element and the optical filter, and incident when the optical element is used as the optical element A method for producing an optical element, comprising: a step of irradiating light in the ultraviolet region from the side to be the side or the side to be the emission side when the optical element is used to cure the composition layer for forming an adhesive layer to form the adhesive layer .

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