JPWO2018180269A1 - Optical element and method for manufacturing optical element - Google Patents

Abstract

An optical element that integrates a deflection element for bending light and an optical filter and has low light loss and is easy to manufacture, and a method for easily manufacturing an optical element in which the deflection element and the optical filter are integrated by an adhesive layer. Offer. A deflecting element that deflects and emits incident light, and an optical filter that is located on the incident side or the outgoing side of the deflecting element and selectively blocks light in at least a part of the region from ultraviolet to near infrared. An adhesive layer between the deflection element and the optical filter, the refractive index of the deflection element being nP, the refractive index of the adhesive layer being nG, and a layer among members included in the optical filter. An optical element that satisfies the relationship of Expressions (1) and (2), where nF is the refractive index of the member having the largest thickness. ΔnGF = | nG−nF | ≦ 0.5 (1) ΔnPG = | nP−nG | ≦ 0.5 (2)

Description

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

  2. Description of the Related Art In a digital still camera or the like, an imaging device equipped with a solid-state imaging device such as a CCD or a CMOS image sensor is becoming smaller and more sophisticated. For example, in an imaging apparatus including a coupling lens system such as a zoom lens and a solid-state imaging device, miniaturization has been achieved by using a deflection element such as a prism that bends light.

  Patent Document 1 has a prism that bends light transmitted through an imaging lens group and a cover glass that transmits the light that has been 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 device 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 has low light loss and is easy to manufacture, and that an optical element in which the deflecting element and the optical filter are integrated by an adhesive layer can be easily manufactured. The purpose is to provide a method for manufacturing.

The optical element of the present invention selectively deflects 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 outgoing side of the deflecting element. And an adhesive layer that integrates the two between the deflecting element and the optical filter. The refractive index of the deflecting element is n _P , the refractive index of the adhesive layer is n _G , and when out layer thickness of members included in the optical filter has a refractive index of the largest member with 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)

The method for manufacturing an optical element according to the present invention includes a deflecting element that deflects incident light and emits the light, and light in at least a part of the region from the ultraviolet region to the near-infrared region located on the incident side or the emission side of the deflecting element. And an adhesive layer that integrates the two between the deflecting element and the optical filter, wherein the refractive index of the deflecting 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 A method for producing an optical element satisfying a relationship of _G | ≦ 0.5, comprising an adhesive layer forming composition layer containing an ultraviolet curable material between the deflection element and the optical filter. Producing a precursor, and the optics Curing the adhesive layer forming composition layer by irradiating ultraviolet light from the side that becomes the incident side when the optical element is used as the optical element or the side that becomes the output side when the optical element is used as the optical element. Including a step of forming an adhesive layer.

  According to the present invention, it is possible to provide an optical element in which a deflection element for bending light and an optical filter are integrated and light loss is small and easy to manufacture. 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 imaging device, if the optical element of the present invention is disposed immediately before the light receiving surface of the solid-state imaging device and used, it is advantageous for downsizing the imaging device.

It is sectional drawing which shows an example of the optical element of embodiment. FIG. 1 is a cross-sectional view schematically illustrating an example of an imaging device including an optical element according to an embodiment. FIG. 3 is a cross-sectional view schematically illustrating a relationship between an incident angle and an outgoing angle of light in the optical element of the embodiment. It is a graph showing the refractive index n _P for totally reflecting the incident angle theta _m in a right angle prism. FIG. 3 is a cross-sectional view illustrating an example of a deflection element used for the optical element according to the embodiment. FIG. 3 is a cross-sectional view illustrating an example of an optical filter used for the optical element according to the embodiment. FIG. 4 is a cross-sectional view illustrating another example of the optical filter used for the optical element of the 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 the reflectance in the optical interface of a different refractive index (n1, n2). It is sectional drawing which shows another example of the optical element of embodiment. FIG. 3 is a cross-sectional view illustrating an example of an optical element according to an embodiment having 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 the present 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 the present specification, the “refractive index” means a refractive index for light having a wavelength of 589 nm. "Curable material" refers to an uncured material before curing, which is cured by heating or light irradiation to form a cured material. "Curable material" is obtained by curing a curable material by heating or light irradiation. Cured product. In this specification, “to” indicating 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 direction of light entry along the optical axis of an imaging device or the like during use. The “outgoing side” of the optical element refers to a side where light incident from the incident side of the optical element is deflected in a predetermined direction, for example, in the direction of an element that receives the outgoing light, and is emitted.

[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 illustrating an example of the optical element according to the present embodiment. FIG. 2 is a cross-sectional view schematically illustrating an example of an imaging apparatus including the optical element of the present embodiment illustrated in FIG.

  The optical element 10 shown in FIG. 1 selectively deflects a deflecting element 1 that deflects incident light and emits the light, and selectively detects 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 device 1. It comprises an optical filter 2 for blocking and an adhesive layer 3 located between the deflecting element 1 and the optical filter 2 and integrating the deflecting element 1 and the optical filter 2. In the optical element 10 shown in FIG. 1, the optical filter 2 is located on the emission side of the deflection element 1, but in the optical element of the present invention, the optical filter 2 may be located on the incidence side of the deflection element 1. In that case, the optical element 10 is arranged in the order of the optical filter 2, the adhesive layer 3, and the deflecting element 1 from the light incident side.

  In FIG. 1, for convenience of description, the direction in which light is emitted from the deflecting element 1 is defined as a Z-axis direction, and two directions that are orthogonal to the Z-axis direction and orthogonal to each other are X-axis directions (directions orthogonal to the paper surface). Defined as the Y-axis direction (direction parallel to the paper). In this specification, the Z-axis direction is referred to as “Z direction”. The same applies to the X-axis direction and the Y-axis direction. In this specification, the X, Y, and Z directions are the same as those shown in FIG. 1 unless otherwise specified. 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 also referred to as “the 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 as “refractive index n _G ”, and the refractive index of the thickest member included in the optical filter as “refractive index n _F ”.

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

  In the optical element 10, light is incident on the incident surface 1 a of the deflecting element 1 from the Y direction, is deflected by reflection on the reflecting surface 1 b of the deflecting element 1, and is 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 2b of the optical filter 2 in the Z direction.

  The optical element of the present embodiment has the functions of the deflection element and the optical filter by integrating the deflection element and the optical filter using the adhesive layer. That is, in the optical element of the present embodiment, the light incident from the incident surface is deflected, and the light in at least a part of the region from the ultraviolet region to the near infrared region is selectively cut off and emitted. Thus, according to the optical element of the present embodiment, the size of the imaging device can be reduced. Further, when the relationship between the refractive index of the deflection element, the adhesive layer, and the optical filter satisfies Expressions (1) and (2), light loss in the optical element of the present embodiment is small.

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

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

  Here, by using the optical element 10 including the object-side prism 6 and the deflection element 1, the thickness of the imaging device 100 in the Z direction is reduced. In particular, 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, it is possible to reduce the thickness of an image pickup apparatus having a zoom lens function and a focus adjustment function. As described above, when the optical element 10 is disposed and used immediately before the solid-state imaging element 4, as shown in FIG. 2, the optical element 10 is disposed in the order of the deflecting element 1, the adhesive layer 3, and the optical filter 2 from the incident side. Preferably.

  In FIG. 2, the optical element 10 is arranged to deflect incident light from the Y direction in the Z direction by the deflecting element 1 and emit the light. In the imaging device 100, the optical element 10 may be arranged so as to be rotated by 90 ° with the Y direction as the rotation axis, whereby the incident light from the Y direction is deflected in the X direction and emitted. it can.

The F number of the imaging lens system of the imaging apparatus 100 including the objective lens 5, the object-side prism 6, and the imaging lens group 8 changes according to the aperture stop diameter. Then, the F number is associated with F = 1 / (2 × NA) using the take-in angle θ and the numerical aperture NA = sin θ, and the radiated light from the subject is taken into 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 °, and 10.4 °, respectively. . That is, light having an incident angle range of −θ _m to + θ _m with respect to the optical axis on the incident surface 1 a of the optical element 10 is incident on the optical element 10.

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

<Deflection element>
FIG. 1 exemplifies a right-angle prism as the deflecting element 1. However, as the deflecting element in the optical element of the present invention, the incident light is deflected and emitted, and in relation to the refractive index with the adhesive layer, the expression (2) is used. if an element having a refractive index n _P that satisfies, can be used without particular limitations.

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

  As the deflecting element, a prism is preferable, and a triangular prism is more preferable, from the viewpoint of stably processing a highly accurate optical reflecting surface. Also, among the triangular prisms, in the cross section of the YZ plane, the angle between the incident surface and the output surface is 90 °, and the angle between the incident surface and the reflective surface (for example, indicated by α in FIG. 3). Further, a triangular prism having an angle between the reflecting surface and the exit surface (for example, represented by β in FIG. 3) in the range of 40 to 50 ° is more preferable, and the cross section of the YZ plane is a right-angled isosceles triangle. = Β = 45 ° right angle prisms are 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. Figure 3 is a schematic diagram showing the relationship between the emission angle theta and the incident angle theta ₀ of the light in the optical element 10 shown in FIG. In FIG. 3, the deflecting element 1 is a triangular prism having a YZ plane cross section that is a right-angled isosceles triangle and extends in the X direction, that is, a right-angle prism (hereinafter, the deflecting element 1 is also referred to as the right-angle prism 1).

  The angle between the entrance surface 1a and the reflection surface 1b of the right-angle prism 1 and the angle between the exit surface 1c and the reflection surface 1b are both 45 °. In FIG. 3, the angle formed by the incident surface 1a and the reflecting surface 1b is represented by α, and the angle formed by the emitting surface 1c and the reflecting surface 1b is represented by β for generalization to the triangular prism. . 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 between the incident surface 1a and the reflecting surface 1b is α, and the incident angle on the reflecting surface 1b is (α−θ ′). Note that the relationship of sin θ ₀ = n _P × sin θ ′ is satisfied by Snell's law of refraction. Here, in order for the incident light on the reflecting surface 1b to be deflected to the outgoing surface 1c by total reflection, it is necessary to satisfy n _P × sin (α−θ ′) ≧ 1. That is, the refractive index n _P of the right-angle prism 1 needs to satisfy the following relationship.

The setting of the incident angle of the convergence or divergence light and the strict condition of the incident angle of the total reflection light is based on the condition of the incident angle θ ₀ (θ ₀ > 0) in the direction of FIG. The incident angle range of the 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 in a region above a 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 and 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 between the exit surface 1c and the reflection surface 1b is β, and the incident angle on the exit surface 1c is (β−α + θ ′). Further, the emission angle θ of the light transmitted through the adhesive layer 3 and the optical filter 2 and emitted from the emission surface 2b of the optical filter 2 to the atmosphere side is sin θ = n _P × sin (β−α + θ ′) according to Snell's law of refraction. Become.

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

Here, we consider a total reflection prism rectangular prism 1 has a maximum incident angle of the incident angle _{θ m = 5~30 ° (n P} = 1.50~1.98). Light totally reflected by the reflecting surface 1b has a range refractive index _{n F} of the refractive index _{n G} is 1.35 to 1.80 and the optical filter 2 of the adhesive layer 3 is 1.35 to 2.50 as described below Then, there is no total reflection at the interface between the right-angle prism 1 and the adhesive layer 3 and 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 the incident light does not satisfy the relationship of the refractive index n _P that is totally reflected on the reflecting surface of the prism, for example, the incident light is incident at n _P = 1.50. When the angle θ ₀ is larger than 5 °, when the incident angle θ ₀ is larger than 16 ° when n _P = 1.70, or when the incident angle θ ₀ is larger than 27 ° when n _P = 1.90. Also, the light loss can be suppressed by forming the reflection layer on the reflection surface. As the reflection layer, for example, 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, “low refractive index”) Film) may be used. A prism having a reflection layer formed on a reflection surface has an advantage that an inexpensive prism material can be used as compared with a case where a prism capable of total reflection on the reflection surface is used. On the other hand, the process of forming the reflective layer becomes a burden, 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.

The deflection element is made of a material having a refractive index n _P that satisfies the expression (2) in relation to the refractive index with 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 take-in angle, the brighter the imaging lens with a smaller F-number. Is more preferred.

When using a right-angle prism as a deflecting element, as described above, n _P is to be provided with a reflective layer on the reflective surface at the maximum incident angle theta _m is 8 ° or more 1.55 or less. Note that, even when a reflective layer is provided, the refractive index n _P is the refractive index of the prism material. In order to enable the total reflection at the maximum incident angle theta _m in rectangular prism, _{n P} is preferably 1.55 than at θ _m = 8 °, _{n P} is preferably 1.60 or more θ _m = 10 °, When θ _m = 15 °, n _P is preferably 1.69 or more, when θ _m = 20 °, n _P is preferably 1.79 or more, and when _{P m} = 25 °, n _P 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. As the glass satisfying 1.70 ≦ n _P <1.80, 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 _{INC, S-LAH66 (n P =} 1.772), S-YGH51 ( n _P = 1.755), include _{S-LAL19 (n P = 1.729} ) and the like.

As the glass satisfying 1.80 ≦ n _P <1.90, J-LASFH22 (n _P = 1.8483), J-LASF05 (n _P = 1.8346), J-LASF09 (n _{P = 1.8158), J-LASF015 (} n P = 1.8038), manufactured by OHARA _{INC, 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), and the like TAF3 (n P = 1.804) and the like.

1.90 The glass of ≦ _{n P,} optical glass _{manufactured, J-LASFH21 (n P =} 1.9535), J-LASFH9 (n P = 1.9024), manufactured by OHARA INC, 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 contains an ultraviolet curable material obtained by using an ultraviolet curable material, and the optical filter has a function of blocking UV, the deflection element has a UV transmittance. Good to have. Note that in this specification, the light transmittance of the deflecting element refers to the light transmittance in the relationship between incident light and light that is deflected and emitted after incidence.

  The UV wavelength at which the deflecting element is required to be transparent is generally in the range of 250 to 400 nm, depending on the UV-curable material used for the adhesive layer. In particular, a wavelength near the i-line (365 nm) where the emission intensity of the HgXe discharge lamp is high is preferably used for curing the ultraviolet curable material. 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 even more preferably 50% or more. Higher transmittance is more advantageous for shortening the UV irradiation time, preferably 70% or more, more preferably 80% or more.

Further, the deflection element may transmit visible light. Any glass aforementioned 1.70 ≦ _{n P,} as well as internal transmittance of the UV wavelength 365nm is 10% or more, in internal transmittance in the visible region of 420nm~700nm 92% or more, glass for deflecting element Can be used as material.

  In the optical element of the present embodiment, when a triangular prism is used as the deflecting element, for example, in the triangular prism 1 shown in FIGS. 1 and 3, three corners in the YZ section are right angles or acute angles, so that chipping occurs. And 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 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 entrance surface 1a and the reflection surface 1b intersect, a W2 surface having a width w2 at a intersection between the reflection surface 1b and the exit surface 1c, and the entrance surface 1a. A corner portion (vertex angle = 90 °) where the light exit surface 1c intersects the C surface having a width c. The W1, W2, and C planes are chamfers. As described above, by having a chamfered portion obtained by chamfering a corner, occurrence of chipping and cracks can be reduced.

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

  Regardless of the presence or absence of the chamfered portion, in the optical element of the present embodiment, since the reflected light path deflection angle on the reflection surface is larger than the refraction light path deflection angle on the transmission refraction surface having the same inclination angle deviation, it is required for the reflection surface. Surface precision is about 2 to 4 times as severe as that of the transmission refraction 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 image pickup device, and the rigidity of the prism material used, the film forming stress on the light incident surface 1a, and the light emitting surface 1c, and the bonding. Depends on the adhesive layer.

  That is, an anti-reflection layer or a reflection layer may be formed on the entrance surface 1a or the exit surface 1c of the triangular prism 11 as described later, and a film stress is generated at that time. In addition, when the optical filter 2 is integrated with the incident surface 1a and the output surface 1c via the adhesive layer 3, a difference in the coefficient of thermal expansion (when a thermosetting material is used for forming the adhesive layer) or polymerization shrinkage is caused. (When a thermosetting material or a photocurable material is used for forming the adhesive layer), residual stress is generated. Under the influence of these stresses, if the chamfer widths w1 and w2 are narrow, the flatness of the end of the reflection surface 1b of the triangular prism 11 may not be ensured in some cases. When such an optical element using the triangular prism 11 is used in, for example, an image pickup apparatus as shown in FIG. 2, there is a possibility that the aberration of the image pickup lens system is deteriorated and the resolution of the image pickup apparatus is reduced. .

  In view of the above, the chamfer widths w1 and w2 of the chamfered portion are each independently preferably 0.1 mm or more, more preferably 0.2 mm or more. If the chamfer widths w1 and w2 are increased, the size of the triangular prism 11 and the entire optical element using the same increases, so that the chamfer widths w1 and w2 are preferably independently 0.4 mm or less. Further, the chamfer width c is preferably about 0.05 to 0.2 mm.

  The chamfered portions W1, W2, and C shown in FIG. 5 are preferably diffusing surfaces so that light incident on this surface does not become stray light, similarly to the side surface of the deflection element described later. Further, it is more preferable that these surfaces are provided with a light-absorbing light-shielding film.

<Adhesive layer>
In the optical element 10, the adhesive layer 3 is provided between the deflecting element 1 and the optical filter 2, and has a function of bonding and integrating them. 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. (1) satisfies the, and as long as the adhesive layer having a refractive index n _G that satisfies the equation (2) in relation to the refractive index of the deflection element 1, can be used without particular limitations.

  The constituent material of the adhesive layer preferably includes a thermosetting material or a photocurable material. As the photocurable material, an ultraviolet curable material is preferable. For the formation of the adhesive layer containing a thermosetting material or a photocurable material, a thermosetting material or a photocurable material that is polymerized and solidified by heating or irradiation with light such as ultraviolet rays, in other words, is cured to fix the adhesive layer. Can be used. Compared with the thermosetting material, the photocuring material completes polymerization and solidification in a short time, and has high productivity. Further, the photocurable material is advantageous when a member having low heat resistance is included because other members constituting the optical element are hardly affected by heat during curing.

  As the photocurable material, an ultraviolet curable material is preferable. 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 near the i-line (365 nm) where the emission intensity of the HgXe discharge lamp is high is often used.

  As the thermosetting material, for example, an epoxy resin # 301, # 301-2, # 310M-1 or the like from EPO-TEK can be used. As the photocurable material, for example, as an ultraviolet curable material, mercaptoester resin from Norland-Products, NOA60 series or epoxy resin from NTT-AT, AT3925M, 3727E, 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. The adhesive layer 3 may be, if necessary, various additives made of a non-curable material other than the curable material, such as a UV absorber, an absorber such as a NIR absorber, a polymerization initiator, It may contain a polymerization inhibitor.

The refractive index n _G of the adhesive layer 3 satisfies Expression (1) in relation to the optical filter 2 and the refractive index n _G satisfies Expression (2) in relation to the deflection element 1. It is. Refractive index _{n G} of the adhesive layer 3, depending on the deflection element 1 and the optical filter 2 combined, specifically, preferably from 1.35 to 1.80, 1.45 to 1.65 is more preferable. If n _G is less than 1.35, preferably in that it can use the inexpensive type of rich refractive index n _F of the material in the thickest member included in the optical filter 2, the refractive index n if 1.80 or less since it is possible to suppress the difference in refractive index between the _P and the refractive index n _F preferred because Fresnel reflection on each interface is small.

  The adhesive layer 3 is transparent to light having a predetermined wavelength to be transmitted by the optical element 10. Although it depends on the optical device in which the optical element is used, it is generally preferable to exhibit high transparency at least to visible light. The thickness of the adhesive layer 3 is preferably from 1 to 20 μm, more preferably from 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 that joins 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 in FIG. 1, first, the adhesive layer 3 in the optical element 10 is a layer made of an adhesive layer forming composition including an ultraviolet curable material for obtaining the adhesive layer 3. Make a precursor. Next, UV is irradiated from the deflection element 1 side or the optical filter 2 side of the optical element precursor to cure the ultraviolet curable material in the layer made of the adhesive layer forming composition to form the adhesive layer 3.

  When the optical element of the present invention is required to have UV blocking properties, a UV reflecting layer is formed on the deflecting element 1 and a layer containing a UV absorber or a UV reflecting layer is formed on the optical filter 2. 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 deflection element side of the optical element, or can enter UV from the optical filter side of the optical element. The optical element is configured to be able to receive the UV light.

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

<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 has a refractive index n _{F of the} thickest member included in the optical filter. There is satisfied formula (1) in relation to the refractive index n _G of the adhesive layer, it can be used without particular limitations.

  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 the optical filter is combined with an adhesive layer containing an ultraviolet curable material, as described above, the deflecting element preferably has UV transmittance. Specifically, when the maximum transmittance at a wavelength of 340 to 390 nm is 10% or more, Preferably it is.

  As such an optical filter, specifically, (i) NIR cut filter which blocks UV and (ii-1) NIR and transmits visible light, and (i) blocks UV and (ii-2) visible light However, an NIR transmission filter that transmits NIR may be used. Further, (i) UV and (ii-3) light in the first region in the near infrared region is blocked, and visible light and light in the second region on the longer wavelength side than the first region in the near infrared region are also blocked. Band-pass filter that transmits light.

  As the (i) UV blocking property of these optical filters, for example, a blocking property of setting the average transmittance of UV at a wavelength of 300 to 400 nm to 10% or less is preferable, and 2% or less is more preferable.

  As the (ii-1) NIR cutoff property of the NIR cut filter, for example, a cutoff property in which the average transmittance of NIR at a wavelength of 700 to 1100 nm is 5% or less is preferable, and 2% or less is more preferable. As the visible light transmittance of 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.

  As the (ii-2) visible light blocking property of the NIR transmission filter, 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 is preferable, and 2% or less is more preferable. . As the NIR transmittance of the NIR transmission filter, for example, it is preferable to have a continuous wavelength range of 40 nm or more where the transmittance becomes 80% or more between NIR wavelengths of 800 to 1000 nm, and it is preferable to have a wavelength range of 80 nm or more.

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

  FIGS. 6A to 6C, which are specific configurations of the optical filter having the selective light blocking property, are YZ cross-sectional views 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, for example, instead of the optical filter 2 of the optical element 10 shown in FIG. In each of the optical filters 2A, 2B, and 2C, the left side indicates the incident surface 2a in contact with the adhesive layer 3, and the right side indicates the exit surface 2b in contact with the atmosphere.

The optical filter 2A shown in FIG. 6A includes only the absorption type substrate 21. The shape of the absorption type substrate 21 is a parallel plate shape having a pair of main surfaces facing each other, and the light is blocked by absorption. In the optical filter 2A is thickest member included in the optical filter is an absorption-type substrate 21, the refractive index n _F of the optical filter 2A is a refractive index of the absorption-type substrate 21.

  Examples of the absorption type substrate 21 include an absorption type glass substrate or a resin substrate containing a resin and an absorption dye (hereinafter, referred to as “absorption type resin substrate”). The thickness of the absorption type substrate 21 depends on the configuration, but is preferably 20 μm or more. 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-type glass substrate is obtained by molding the absorption-type glass into a parallel plate shape. Examples of the absorption type glass include a fluorophosphate glass containing CuO, a phosphate glass containing CuO, and the like. Hereinafter, the fluorophosphate-based glass containing CuO and the phosphate-based glass containing CuO are collectively referred to as “CuO-containing glass”.

  CuO-containing glasses typically have the ability to absorb NIR at wavelengths of 700-1100 nm. In the CuO-containing glass, the absorption capacity in the near infrared region can be adjusted by adjusting the CuO content and the thickness.

Further, for example, a 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, and the} like, has a short wavelength side in the ultraviolet region, For example, it has absorption characteristics at a wavelength of 300 nm or less. The refractive index of the absorption-type glass substrate is preferably 1.40 to 1.75, and more preferably 1.45 to 1.60, as the refractive index of the CuO-containing glass.

  The absorption type resin substrate is a substrate in which an absorption dye is uniformly dissolved or dispersed in a resin. The resin is a matrix component for forming a parallel plate shape, and is preferably a transparent resin. As the absorbing dye, a dye that selectively absorbs light having a cutoff wavelength required for the optical filter 2 is used. Specifically, 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 (i) above. And any of the absorbing dyes that selectively absorb light in the wavelength ranges respectively corresponding to (ii-1), (ii-2), and (ii-3).

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

  The optical filter 2B shown in FIG. 6B includes a parallel plate-shaped substrate 21B having a pair of main surfaces facing each other, and an absorption layer 22 formed on one main surface of the substrate 21B. In the optical filter 2B, the main surface of the substrate 21B that is not in contact with the absorption layer 22 is the incident surface 2a that is in contact with the adhesive layer 3, and the main surface of the absorption layer 22 that is not in contact with the substrate 21B 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 of the substrate 21B on the side opposite to the adhesive layer 3 side. The optical filter 2 used in the optical element 10 may have a configuration having the absorption layer 22 on the side of the adhesive layer 3 of the substrate 21B. However, the absorption layer 22 is formed on the main surface of the substrate 21B on the side opposite to the adhesive layer 3 side, from the viewpoint that the reflected light is more likely to be stray light affecting the image quality deterioration as the layer is closer to the light receiving surface of the solid-state imaging device. Optical filter 2B is preferred.

The substrate 21B may be the same absorption type substrate as the absorption type 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, lithium niobate, a crystal such as sapphire, a chemically strengthened glass obtained by chemically strengthening soda lime glass, etc., a crystallized glass, a substrate made of a transparent resin, and the like. These thicknesses can be made the same as those of the above-mentioned absorption type glass substrate and absorption type resin substrate. The thickness of the absorption layer 22 is 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. Refractive index _{n F} of the optical filter 2B is the refractive index of the substrate 21B.

  When the substrate 21B is glass, the refractive index of the substrate 21B is preferably 1.40 to 1.75, and more 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 more 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. The absorption layer 22 can be formed on the substrate 21B by, for example, a method such as wet coating, so that the absorption layer 22 can be made thinner. Are different. The thickness of the absorbing 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 light in at least a part of the region from the ultraviolet region to the near-infrared region when the absorbing layer 22 and the substrate 21B are combined to form the optical filter 2B. .

  Specifically, a UV-absorbing dye that selectively absorbs light in the wavelength range corresponding to the above (i), the wavelength ranges respectively corresponding to the above (ii-1), (ii-2), and (ii-3) Absorbing dyes that selectively absorb the light of the above. As the absorbing dye, when the absorbing layer 22 and the substrate 21B are combined to form the optical filter 2B, the absorbing dye capable of exhibiting 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 a laminated absorbing layer 22.

  The optical filter 2C shown in FIG. 6C is formed of 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. Made of the reflective layer 23. In the optical filter 2C, the main surface of the reflection layer 23 that is not in contact with the substrate 21C is the incident surface 2a that is in contact with the adhesive layer 3, and the main surface of the absorption layer 22 that is not in contact with the substrate 21C is the emission surface 2b that is in contact with the atmosphere. .

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

The substrate 21C can be made similar to the substrate 21B in the optical filter 2B. When the absorption layer 22 is used as the optical filter 2C, except that the absorption dye to be used is appropriately selected so that the cutoff characteristics required for the optical filter 2 can be obtained in combination with the absorption characteristics of the substrate 21C and the reflection characteristics of the reflection layer 23. And the absorption layer 22 in the optical filter 2B. In addition, since the thickness of the reflective layer 23 is about 1 to 10 μm as described below, in the optical filter 2C, the thickest member included in the optical filter is the substrate 21C. Refractive index _{n F} of the optical filter 2C is a 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. It is preferable that the reflection layer 23 has a reflection characteristic indicating the absorption and transmission characteristics of the NIR cut filter, the NIR transmission filter, or the band transmission filter by functioning complementarily to the substrate 21C and the absorption layer 22.

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

  The reflection layer 23 is preferably formed of a dielectric multilayer film in which low-refractive-index films and high-refractive-index films are alternately stacked. The dielectric multilayer film may have a configuration including a metal film as necessary.

  According to the required optical characteristics, the dielectric multilayer film is designed with a specific number of layers and film thickness, and a refractive index of a high refractive index material and a low refractive index material to be used by using a conventionally known method. , Can be manufactured. When the reflective layer 23 is a dielectric multilayer film, the total thickness is preferably 1 to 10 μm, 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 the like, which are included in the configuration of the optical filters 2A, 2B, and 2C, and their constituent materials are described in, for example, WO2016 / 114362A. Is exemplified.

  Although the example of the optical filter 2 has been described with reference to FIGS. 6A to 6C, the optical filter 2 is not limited to the configuration of the optical filters 2 </ b> A, 2 </ b> B, and 2 </ b> C. 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. In the optical filter 2 including the substrate 21B and the absorption layer 22, the optical filter 2 may have the absorption layer 22 formed on both main surfaces of the substrate 21B.

<Refractive index _{n P,} the relationship of the refractive index _{n G} and the refractive index _{n F>}
The relationship between the refractive index of the deflection 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 reflectance R [%] of the reflected light generated at the optical interface having different refractive indices n1 and n2 can be approximated by the following equation when the incident angle is 30 ° or less according to the Fresnel reflection law.

R = | n1-n2 | ² / (n1 + n2) ²
That, Δn = | n1-n2 | and ^{when, R = Δn 2 / (n1} + n2) 2 becomes, [Delta] n> 0.3 in R> 0.09 / (n1 + n2 ) 2, Δn> in 0.2, R> 0 .04 / (n1 + n2) ² , and when 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.

_N G + _{n F} and _n P + _{n G} in the optical element of the present invention is 2.6 or more determined in view of real optical material having a transmission wavelength band in the range of the wavelength 350～1100Nm. 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 the optical interfaces having different refractive indexes (n1, n2).

  From FIG. 7, when (n1 + n2) ≧ 2.6, when Δn = 0.5, R ≦ 3.70%, when Δn = 0.4, R ≦ 2.37%, and when Δn = 0.3, R ≦ 1. 33%, R ≦ 0.59% when Δn = 0.2, and R ≦ 0.15% when Δn = 0.1.

By satisfying the 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 the reflected light generated at the interface between the optical material having the refractive index n1 = 1.5 or more and the air having the 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 reducing the reflectance of Fresnel reflected light, Δn _GF and Δn _PG are preferably equal to or less than 0.3, more preferably equal to or less than 0.2, and particularly preferably equal to or less than 0.1. When Δn _GF is 0.2 to 0.5 and the reflectance at the interface 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. When Δn _PG is 0.2 to 0.5, an antireflection layer may be similarly formed on the interface between the deflection element and the adhesive layer. Since it is difficult to form the antireflection layer on the adhesive layer, it is preferable to form the antireflection layer on the surface of the optical filter that contacts the adhesive layer or the surface of the deflection element that contacts the adhesive layer.

  The above 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.

<Anti-reflective layer>
As described above, the optical element of the present invention has the 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 relationships of Expressions (1) and (2). You may. Further, the optical element may have an anti-reflection layer on a surface in contact with the atmosphere. The anti-reflection layer may be provided at one place, two places, or all places. In particular, when the reflectance of 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 shows an example of the optical element of the present embodiment, which further has an antireflection layer. The optical element 10A shown in FIG. 8 is different from the optical element 10 shown in FIG. 1 in that, in addition to the deflecting element 1, the adhesive layer 3, and the optical filter 2, an antireflection layer 12a, an anti-reflection layer 12b on an emission surface 1c which is an interface in contact with the adhesive layer 3 of the deflection element 1, an anti-reflection layer 13a on an incidence surface 2a which is an interface in contact with the adhesive layer 3 of the optical filter 2, and air in the optical filter 2. The structure has an antireflection layer 13b on the exit surface 2b which is an interface with.

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 Can be used.

The antireflection layer 12b is provided according to the value of Δn _PG . For example, when Δn _PG is 0.1 or less, as shown in FIG. 7, the reflectance R ≦ 0.15%, so that 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 may be provided. As the anti-reflection layer 12b, an anti-reflection layer made of a single-layer dielectric film having a refractive index of n _c and a thickness of d _c , specifically, an anti-reflection layer that satisfies the following two equations is used. The reflectance R at the interface between the element 1 and the adhesive layer 3 can be reduced.

ここで、λ_ｃは、光学素子１０Ａからの出射光に求められる光の中心波長、例えば、図２に示す撮像装置１００において固体撮像素子４で検出する入射信号光の中心波長に相当し、最短波長λ_Ｓと最長波長λ_Ｌを用いて、λ_ｃ＝２×λ_Ｓ×λ_Ｌ／（λ_Ｓ＋λ_Ｌ）と規定される。

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 imaging device 4 in the imaging device 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 to 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. 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 like the antireflection layer 12a.

Antireflective layer 13a is antireflection layer 12b is similar to that provided in accordance with the value of [Delta] n _PG, is provided in accordance with the value of [Delta] n _GF. 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 anti-reflection 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 stacked may be used. In the optical element 10A shown in FIG. 8, the optical filter 2 may be, for example, the optical filters 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 the function of shutting off. The optical element of the present invention may have a configuration in which a part of these blocking performances is shared by components 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 formed by, for example, an optical element 10A shown in FIG. May be provided instead of the anti-reflection layer 12a or the anti-reflection layer 12b on the entrance surface 1a or the exit surface 1c of the deflecting element 1 in the above. In this case, the optical filter 2 may be configured to have no light blocking property of the reflection layer provided on the deflection element 1. In this way, the optical element as a whole is designed to have the performance of transmitting and blocking light in a predetermined area.

<Light shielding film>
For example, when the optical element of the present invention is used in an imaging device, it becomes necessary to reduce stray light due to scattering or reflection from various optical members included in the imaging device and its holding member. For the purpose of reducing the stray light or the like, a first light-shielding film that partially blocks light that enters the optical element from the incident side and / or a second light-shielding film that blocks light that enters the optical element from the side. It is better to further comprise.

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

For example, in the imaging apparatus 100 shown in FIG. 2, the incident angle range of −θ ₀ to + θ ₀ defined according to the F number of the imaging lens system (the objective lens 5, the object-side prism 6, and the imaging lens group 8). The light enters the optical element 10 and is deflected, while unnecessary light is blocked and emitted to the solid-state imaging device 4 and reaches the light receiving surface 41 of the solid-state imaging device 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 enters the optical element 10 as stray light, it causes image quality deterioration. 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 device 100 needs It is preferable to have a light-shielding film in the region. When the light-shielding film is formed on the optical element 10 close to the light receiving surface 41 of the solid-state imaging device 4 in the imaging device 100, it is effective in removing stray light.

  The optical element 10 preferably has a first light-shielding film that partially blocks light from the incident side of the optical element 10. Further, it is preferable that the optical element 10 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, 10, 11, and 12 show cross-sectional views, plan views, or perspective views of optical elements 10B, 10C, 10D, and 10E having a light-shielding film in the optical element of the present invention, respectively. Each of the optical elements 10B, 10C, and 10D shown in FIGS. 9A, 9B, 10, and 11 includes 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. This 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 a side surface of the optical element.

  9A shows an optical element 10B in which a light-shielding film 15 is formed at the interface of the optical filter 2 with the air 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 deflecting element 1, the adhesive layer 3, and the optical filter 2 can be the same as the optical element 10.

  In the optical element 10 </ b> B, the shape of the light-shielding film 15 has a frame shape whose outer periphery coincides with the outer periphery of the emission surface 2 b of the optical filter 2 in the shape of the main surface. By forming the light-shielding film 15 in such a frame shape, for example, when the optical element 10 </ b> B is disposed in the imaging device 100 shown in FIG. 2 instead of the optical element 10, the light enters the light receiving surface 41 of the solid-state imaging element 4. The central portion secures a rectangular signal light emission area 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 configuration in which a metal film of Cr or the like and an antireflection layer of CrOx or the like for preventing surface reflection of the metal film are laminated, or a resin light-shielding film containing a light-absorbing agent and resin exhibiting light-shielding properties And the like. 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. The resin light-shielding film is formed, for example, by using a light absorbing agent and a photocurable material (resin) on the emission surface 2b of the optical filter 2 by a printing method or a photolithography method so as to have the above-described shape.

  Note that a method for forming a light absorbing agent, a photocurable material (resin), and a light-shielding film containing these in a resin light-shielding film is exemplified in WO2014 / 021245A, for example.

  The thickness of the light-shielding film 15 is preferably about 50 to 500 nm in the case of a configuration 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 from 0.2 to 100 μm, and even more preferably from 0.5 to 10 μm.

  The optical element 10C shown in FIG. 10 is an example in which the light-shielding film 15 is provided not on the emission surface 2b of the optical filter 2 but on the incident surface 2a of the optical filter 2 in the optical element 10B shown in FIGS. 9A and 9B. The optical element 10D shown in FIG. 11 is an example in which the light shielding film 15 is provided not on the emission surface 2b of the optical filter 2 but on the incident surface 1a of the deflection element 1 in the optical element 10B shown in FIGS. 9A and 9B. is there.

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

  The optical element 10E shown in FIG. 12 is an example in which the optical element 10 shown in FIG. 1 has a light-shielding film 15B over the entire side surfaces of the deflection element 1 among the side surfaces of the optical element.

  The deflecting element 1 in the optical element 10 shown in FIG. 1 is a triangular prism, and the side surfaces 1d and 1e orthogonal to the light entrance / exit surfaces 1a and 1c have large areas. Therefore, when the stray light entering the prism reaches the side surface, it may be reflected and transmitted through the light exit surface 1c and exit from the optical element 10. In that case, for example, in the imaging device 100 illustrated in FIG. 2, the ratio of the stray light emitted from the optical element 10 reaching the light receiving surface 41 of the solid-state imaging device 4 is high. In particular, in the case of a triangular prism having a high refractive index, 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 like the optical element 10E, the reflected light itself from the side surfaces 1d and 1e can be sufficiently reflected by, for example, regular reflectance. To 5% or less, and stray light emitted from the optical element 10 can be suppressed to a low level. The configuration of the light-shielding film 15B other than the shape, for example, a layer configuration, a constituent material, and a forming method can be the same 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 the side surfaces 1d and 1e are formed as diffusion surfaces whose surfaces are not flat because the substantial stray light is further reduced.

  As a method of making the side surfaces 1d and 1e diffusion surfaces, when the deflecting element 1 is processed into a triangular prism shape, the side surfaces 1d and 1e are cut with a roughened surface, or the side surface 1d is cut after cutting. And 1e are lapped and polished to form a diffusion surface corresponding to a number 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 making the side surfaces 1d and 1e of the deflection element 1 diffusion surfaces. That is, by using the side surfaces 1d and 1e of the deflecting element 1 as diffusion surfaces, generation of total reflection light generated on the optical flat surface is suppressed (light transmitted to the air side is increased) and incident light is diffused at a wide angle. Thus, for example, the amount of stray light incident as a bright spot on the light receiving surface 41 of the solid-state imaging device 4 can be reduced. In the optical element of the present invention, as described above, the light-shielding film 15B is preferably formed on the side surfaces 1d and 1e of the deflecting element 1 after forming the diffusion surface.

<Modification of optical element>
In each of the above-described optical elements of the present embodiment, the size (outer edge) of the exit surface 1c of the deflection element 1 and the entrance / exit surfaces 2a, 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) a configuration in which the outer edge of the prism is inside the outer edge of the optical filter on each surface of the optical filter opposite to the prism; (II) In each surface where the prism and the optical filter face each other, the outer edge of the prism may be located outside the outer edge of the optical filter.

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

In the optical element 10F, the outer edge of the emission surface 1c of the deflection element 1 is located inside the outer edges of the input / output surfaces 2a and 2b 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 / 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 reliably include the outer periphery of the deflecting element 1 and stray light can be reliably reduced.

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

In the optical element 10 </ b> G, the outer edge of the output surface 1 c of the deflection element 1 is located outside the outer edges of the input / output surfaces 2 a and 2 b of the optical filter 2. 14A and 14B, the length in the Y direction of the emission 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 input / output 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), the dimensional accuracy of the optical element is smaller than that in the case where the outer edge on the emission side of the optical element matches the outer edge of the deflection element 1 and the outer edge of the optical filter 2. This is advantageous in that

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

[Production method]
The production method of the present invention specifically includes the following steps (A) and (B).
(A) A step of producing an optical element precursor having an adhesive layer forming composition layer containing an ultraviolet curable material between a deflection element and an optical filter (here, the optical element precursor is an optical element to be produced) (This is a configuration in which a bonding layer forming composition layer containing an ultraviolet curable material is provided instead of the bonding layer at the position where the bonding layer of the element is provided.)
(B) curing the adhesive layer forming composition layer by irradiating the precursor of the optical element with light in the ultraviolet region from the side that is the incident side when the optical element is formed or the side that is the emission side when the optical element is formed; Process to form an adhesive layer

  Hereinafter, each step 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.

Step (A) In the step (A), the deflecting element 1 and the optical filter 2 located on the emission side of the deflecting element 1 are located between the deflecting element 1 and the optical filter 2 and cured by the following (B) step. This is a step of producing a precursor of the optical element 10 having the adhesive layer forming composition layer, which becomes the adhesive layer 3 for integrating the deflection element 1 and the optical filter 2.

  The composition for forming an adhesive layer constituting the composition layer for forming an adhesive layer contains an ultraviolet curable material. The UV curable material is as described above. The composition for forming an adhesive layer preferably contains the above-mentioned photopolymerization initiator and, if necessary, contains various additives. 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 production process of the optical element.

  In the preparation of the precursor of the optical element 10, a composition for forming an adhesive layer containing the above-described components is prepared, and the cured film is formed on the emission surface 1 c of the deflection element 1 so as to have a desired thickness. Then, 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 adhesive layer forming composition layer such that the incident surface 2a of the optical filter 2 is in contact with the composition layer. When the adhesive layer forming composition 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 2 a of the optical filter 2. In that case, the deflecting element 1 is laminated so that the emission 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 adhesive layer forming composition to be used contains a solvent, the solvent is dried and removed before the deflection element 1 is laminated. Thus, a precursor of the optical element 10 having the adhesive layer forming composition layer instead of the adhesive layer 3 in the optical element 10 is produced.

(B) Step Regarding the precursor of the optical element 10 obtained in the step (A), UV is applied to the adhesive layer forming composition layer according to the curing conditions of the ultraviolet curable material contained in the adhesive layer forming composition. Irradiate. Thereby, the ultraviolet curable material is cured, and the optical element 10 having the adhesive layer 3 containing the ultraviolet curable material is obtained.

  As a method of irradiating the adhesive layer forming composition layer with UV, the precursor of the optical element 10 is irradiated with UV from the entrance surface 1a side of the deflection element 1 or from the exit surface 2b side of the optical filter 2. There is a method of irradiating UV. If the reflecting surface 1b of the deflecting element 1 is a total reflecting surface and no reflective material is formed to block UV light from entering the deflecting element 1, UV may be irradiated from the reflecting surface 1b side.

  In the case where the deflecting element 1 is provided with a UV reflection layer, or in the case where the optical filter 2 has an absorption layer or a reflection layer having a function of blocking UV, the transmittance of UV used for photopolymerization and curing is high. It is preferable to irradiate UV 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 is irradiated with UV from the incident surface 1a side or the reflecting surface 1b side of the deflecting element 1 to form a composition for forming an adhesive layer. The material layer is used as an adhesive layer. When the deflecting element 1 is provided with a UV reflection layer, the optical filter 2 is designed so as not to have a UV blocking property, and is irradiated with UV from the exit surface 2b side of the optical filter 2 to form an adhesive layer. The composition layer is used as 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, a production example of 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 whose specific wavelength range of the incident light is blocked by an optical filter integrated on the exit surface of the deflecting element using an adhesive layer. An example of manufacturing an optical element of the present invention that emits light from the emission surface of the optical filter will be described below with reference to FIG.

  An optical element 10H whose sectional view is shown in FIG. 15 includes a deflecting element 11 similar to that shown in FIG. 5, an optical filter 2C shown in FIG. 6C on the emission side of the deflecting element 11, and a deflecting element 11 and an optical filter 2C. There is an adhesive layer 3 between them. The optical element 10H has an anti-reflection layer 12a on the entrance surface 1a of the deflection element 11, an anti-reflection layer 12b on the exit surface 1c of the deflection element 11, and an anti-reflection film 13b on the exit surface 2b of the optical filter 2C. The optical element 10H further has, on the antireflection film 13b, a light-shielding film 15 having a frame shape whose outer periphery matches 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 region 400~1100nm to cutting of 10% or more of the optical glass triangular prism shape.

Here, the cross section of the triangular prism is an isosceles right triangle having a vertex angle of 90 °. The light incident surface that enters from the Y direction, the light exit surface that exits in the Z direction, and the total reflection surface that deflects from the Y direction to the Z direction are all polished to optical mirror surfaces. Further, the C surface processing and the W1 surface and the W2 surface are performed to obtain each chamfered portion. The width of the isosceles surface, which is the light entrance / exit surface of the triangular prism, is processed so as to cover the signal light effective width Φin of the light incident surface and the signal light effective width Φout of the light exit surface. For the triangular prism, which is the deflection element 11, J-LASFH21 manufactured by Kogaku Glass Co., Ltd., having n _P = 1.954 and having an internal transmittance of 26% at a wavelength of 365 nm and a thickness of 10 mm, is 26%.

  Next, antireflection layers 12a and 12b are formed so as to cover the effective width Φin and Φout of the air interface as the light incident surface 1a of the triangular prism and the adhesive layer interface as the light emitting surface 1c. Is set to 0.5% or less for the signal light wavelength range.

  Next, the triangular prism is cut into an 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. Diffuse surface. To prevent the light incident from the cut surfaces 1d and 1e from becoming stray light, a composition for forming a light-shielding film containing a light absorbing agent and an ultraviolet curable resin is further applied thereon, and the light-shielding film 15B is formed by UV irradiation. To form a deflection element 11 with a light-shielding film.

(Production 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. Having.

As the substrate 21C of the optical filter 2C, a 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, where n _F ≒ 1.52. A reflection 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 on the adhesive layer 3 side of the optically polished NIR absorption type glass substrate 21C. Further, an absorption layer 22 containing an NIR absorption dye having an absorption maximum wavelength at 650 to 750 nm is formed on the air interface on the light emission 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 near 900 nm. However, if the absorption of NIR is to be increased, absorption occurs in visible light, and the transmittance of visible light is reduced. Therefore, the thickness of the glass substrate is adjusted so as to suppress a decrease in the transmittance of visible light. Similarly, the content of the NIR absorbing dye in the absorbing layer 22 is adjusted so as to suppress a decrease in the transmittance of visible light. When the NIR absorption type glass substrate 21C and the absorption layer 22 are adjusted so as to suppress a decrease in the transmittance of visible light, wavelength ranges in which transmitted light occurs at 350 to 400 nm and 700 to 1100 nm are generated. The reflection layer 23 for the wavelength band is designed.

Incidentally, shows a small number of layers and the total thickness of the high transmittance in the visible range of wavelengths 420~660nm at the reflection layer 23 of, so that it can realize a low transmittance in the reflection wavelength band, the refractive index n _F of the glass substrate 21C differences on the premise of using the adhesive layer 3 of 0.1 or less of the refractive index n _G, to design a dielectric multilayer film.

  Here, in the reflection layer 23, the reflection wavelength band shifts to a short wavelength region as the incident angle of the incident light increases, and the spectral transmittance of the entire optical filter 2C changes, which leads to deterioration of image quality. The absorption layer 22 complements the NIR absorption of the NIR absorption type glass substrate 21C, and also has a role of reducing the incident angle dependence 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 at the interface with respect to the signal light wavelength region is set to 0.5% or less. Further, a frame-shaped light-shielding film 15 is formed in a peripheral area other than the signal light transmission effective area of the air interface of the anti-reflection layer 13b, to obtain an optical filter 2C with a light-shielding film.

(Production of Optical Element by Forming Adhesive Layer 3)
The optical filter 2C with the light-shielding film manufactured in this manner is adhered and fixed to the deflection element (triangular prism) 11 with the light-shielding film manufactured as described above, so that the adhesive surface of the deflection element (triangular prism) 11 or the optical filter 2C is cured. The liquid adhesive layer forming composition containing the ultraviolet curable material described above is applied to form an adhesive layer forming composition layer, and the light-shielding film-equipped deflecting element 11 or the light-shielding film-equipped optical filter 2C is laminated thereon. To obtain a precursor of the optical element. The thickness of the adhesive layer forming composition 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 and / or the total reflection surface of the deflecting element (triangular prism) 11 to polymerize and solidify the ultraviolet curable material in the adhesive layer forming composition layer to obtain the adhesive layer 3.

As the adhesive layer 3, the case of using a UV-curable material, for example, when the refractive index _{n G} after curing of NorlandProducts Inc. NOA61 of 1.56, [Delta] n _GF = _| for = 0.04, | n _G -n F 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, the interface between the deflecting element (triangular prism) 11 and the adhesive layer 3 has an antireflection layer 12b.

Incidentally, in the optical element 10H, when the difference in refractive index n _P and the refractive index n _G is small, 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 A configuration may be adopted in which the adhesive layer 3 is provided between the optical filter 2B and the reflection layer 23 on the emission surface 1c of the deflection element 11, and the antireflection layer 12b is not provided. In this case, the anti-reflection layer 12a, the anti-reflection 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 deflecting function and a selective blocking function.In an imaging device such as a digital still camera using a solid-state imaging device, the optical device is disposed immediately before the light receiving surface of the solid-state imaging device. If used, it is advantageous for miniaturization of the imaging device.

10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H ... optical elements,
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: anti-reflection layer, 15, 15B: light shielding film,
4 solid-state imaging device, 5 objective lens, 6 object-side prism, 7 lens moving mechanism, 8 imaging lens group, 100 imaging device.

Claims (20)

A deflecting element that deflects incident light and emits it;
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 outgoing side of the deflection element,
An adhesive layer that integrates both between the deflection element and the optical filter,
When the refractive index n _P of the deflecting _element, the refractive index n _G of the adhesive _layer, and among layer thickness of members included in the optical filter is the refractive index of the largest member to the n _F, the formula (1) And an optical element that satisfies the relationship of Expression (2).
Δn _GF = | n _G −n _F | ≦ 0.5 (1)
Δn _PG = | n _P −n _G | ≦ 0.5 (2)   The optical element according to claim 1, wherein the deflection element is a prism.   The optical element according to claim 2, wherein the prism is a right-angle prism. The optical element according to claim 2, wherein a refractive index n _{P of the} prism is 1.70 or more.   The optical element according to claim 1, wherein the adhesive layer includes an ultraviolet curable material.   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, light in an ultraviolet region incident from an incident side of the deflection element does not pass through an exit side of the optical filter. The optical filter, while blocking light in the ultraviolet region, selectively blocks light in at least a part of the region from the visible region to the near infrared region,
The optical element according to claim 5, wherein the deflection element has a maximum transmittance of light having a wavelength of 340 to 390 nm of 10% or more.   The optical element according to claim 7, wherein the optical filter is a near-infrared cut filter that transmits light in a visible region and blocks light in a near-infrared region.   The optical element according to claim 1, wherein the member having the largest layer thickness in the optical filter is a glass substrate.   The optical element according to claim 9, wherein the glass substrate is made of a fluorophosphate-based glass containing CuO or a phosphate-based glass containing CuO.   The optical element according to claim 9, wherein the optical filter has an absorbing layer containing a resin and an absorbing dye on at least one surface of the glass substrate.   The optical element according to claim 1, 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, wherein the optical filter has an absorbing layer containing a resin and an absorbing dye on at least one surface of the resin substrate.   The optical element according to any one of claims 9 to 14, wherein the optical filter includes a reflective layer formed of a dielectric multilayer film that blocks light in a part of an ultraviolet region.   The optical element according to claim 1, further comprising a first light shielding film that partially blocks light incident on the optical element from an incident side.   The optical element according to claim 1, further comprising a second light-shielding film that blocks light incident on the optical element from a side surface.   The optical element according to any one of claims 2 to 17, wherein an outer edge of the prism is located inside an outer edge of the optical filter on each surface of the optical filter opposite to the prism.   The optical element according to any one of claims 2 to 17, wherein an outer edge of the prism is located outside an outer edge of the optical filter on each surface of the optical filter opposite to the prism. A deflecting element that deflects and emits incident light, and an optical filter that is located on the incident side or the outgoing side of the deflecting element and selectively blocks light in at least a part of the region from ultraviolet to near infrared. An adhesive layer that integrates the two between the deflection element and the optical filter,
The refractive index n _P of the deflecting _element, and the refractive index n _G of the adhesive _layer, and the out layer thickness of members included in the optical filter of the refractive index of the largest member to the n _F, Δn _{GF =} | A method for producing an optical element, which satisfies a relationship of n _G −n _F | ≦ 0.5 and Δn _PG = | n _P −n _G | ≦ 0.5,
Producing an optical element precursor having an adhesive layer forming composition layer containing an ultraviolet curable material between the deflecting element and the optical filter; and entering the optical element precursor when the optical element is used as the optical element. A step of irradiating ultraviolet light from the side to be the side or the side to be the emission side when the optical element is used to cure the adhesive layer forming composition layer to form the adhesive layer. .

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