JP2012108204A - Optical element, method for manufacturing optical element and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element improved in dust resistance and having good optical characteristics, a method for manufacturing the optical element and an electronic device.SOLUTION: An optical element comprises a substrate 1 and an optical function film that is provided on the substrate 1 and includes a plurality of low-refractive index layers 2A and high-refractive index layers 2B alternately stacked. An uppermost layer 2S farthest from the substrate 1 in the optical function film is a first low-refractive index layer 2A, and a first high-refractive index layer 2B adjacent to the first low-refractive index layer 2A includes a plurality of layers of a conductive layer 22 and a non-conductive layer 23 successively provided in this order from a side of the uppermost layer 2S. When the optical function film is an ultraviolet-infrared cut filter film, the conductive layer 22 has a physical film thickness of 60 nm or less.

Description

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

An optical element having a UV-IR cut filter film or an antireflection film is incorporated in an electronic apparatus such as a video apparatus such as a projector, an imaging apparatus such as a digital camera, or a recording / reproducing apparatus such as an optical pickup.
Such an optical element is required to be dustproof because it adversely affects optical characteristics when dust adheres.
The dust-proof optical element has a structure in which an antireflection film or a UV-IR cut filter film is alternately laminated with a low refractive index layer and a high refractive index layer, and is adjacent to the outermost low refractive index layer. The high refractive index layer to be formed is made of ITO (Indium Tin Oxide). Thus, by forming the ITO conductive layer adjacent to the outermost layer, the chargeability of the outermost layer is lowered and the dustproof property is improved (from Patent Document 1 to Patent Document 3).
In the conventional example of Patent Document 3, as an antireflection film, a cerium oxide layer having a physical film thickness of 71 nm, a silicon oxide layer having a physical film thickness of 118 nm, and a physical film thickness of 8.1 nm are sequentially arranged from the substrate side. A conductive layer of ITO and a silicon oxide layer as the outermost layer having a physical film thickness of 10 nm are formed.

Japanese Patent No. 4207083 Japanese Patent No. 4462197 International Publication No. 2008/018340

However, in an optical element such as Patent Document 1 to Patent Document 3, when a conductive material that absorbs light, such as ITO, is used, the light transmittance is low, and an imaging device that requires high definition is required. There is a problem that the optical properties are insufficient for application to the above.
Here, in order to reduce the amount of light absorbed by ITO, it is conceivable to make the ITO conductive layer thin. However, when the physical film thickness of the conductive layer is small, the optical film thickness necessary for the high refractive index layer cannot be secured. As a result, reflection of light cannot be satisfactorily prevented, resulting in a problem that light transmittance is reduced.
Furthermore, in the optical element as described in Patent Document 3, since the outermost layer and the conductive layer are thin, there is a problem in that the optical element is likely to be peeled off and the optical characteristics may be deteriorated. In addition, in the optical element as disclosed in Patent Document 3, since only the outermost layer and the conductive layer function as an antireflection film, there is a problem that a band where light reflection can be prevented is very narrow. From this point of view, the optical element as disclosed in Patent Document 3 has a problem that the optical characteristics are insufficient and it is difficult to apply to an imaging apparatus or the like that requires high definition.

  An object of the present invention is to provide an optical element, a method for manufacturing an optical element, and an electronic apparatus that can improve dustproofness and have excellent optical characteristics.

[Application Example 1]
An optical element according to this application example is an optical element that includes a substrate and an optical functional film that is disposed on the substrate and in which a plurality of low refractive index layers and high refractive index layers are alternately stacked. The outermost surface layer of the optical functional film that is farthest from the substrate is a first low refractive index layer, and the first high refractive index layer adjacent to the first low refractive index layer is composed of a plurality of layers, The plurality of layers are configured by sequentially arranging a conductive layer and a non-conductive layer from the outermost layer side, and when the optical functional film is a UV-IR cut filter film, the physical thickness of the conductive layer is less than 60 nm. It is characterized by.

In this application example having this configuration, since the conductive layer is formed on the first low refractive index layer side of the outermost layer, the charge of the first low refractive index layer can be moved to the conductive layer to reduce the chargeability. . Therefore, the dustproof property of the optical element can be easily improved.
In addition, since the first high refractive index layer is composed of a conductive layer and a nonconductive layer made of another high refractive index material, the light transmittance is reduced by reducing the physical film thickness of the conductive layer. In addition, the non-conductive layer can secure the necessary optical film thickness as the first high refractive index layer. Thereby, the light transmittance can be improved.
Further, when the optical functional film is an antireflection film, the antireflection film is composed of a plurality of low refractive index layers and a plurality of high refractive index layers, so that reflection can be prevented well over a wide band. And the 1st high refractive index layer can be made hard to peel by enlarging the physical film thickness of the nonelectroconductive layer which comprises a 1st high refractive index layer.
Therefore, in this application example, the dust resistance can be improved, and an optical element having excellent optical characteristics can be provided.

[Application Example 2]
In the optical element according to this application example, the conductive layer has a smaller physical film thickness than the non-conductive layer.
In this application example having this configuration, by reducing the physical film thickness of the conductive layer compared to the non-conductive layer, light absorption can be suppressed and light transmittance can be improved.

[Application Example 3]
In the optical element according to this application example, the first low refractive index layer has the lowest density among the plurality of low refractive index layers.
In this application example having this configuration, by reducing the density of the outermost layer, voids are formed in the layer, so that the efficiency of charge transfer to the conductive layer increases and the dustproof performance can be improved.

[Application Example 4]
In the optical element according to this application example, the surface resistance value of the optical functional film is 1 × 10 ⁶ Ω / cm ² or less.
In this application example having this configuration, since the surface resistance value is 1 × 10 ⁶ Ω / cm ² or less, the dust resistance can be improved.

[Application Example 5]
In the optical element according to this application example, the optical functional film functions in a wavelength band from 400 nm to 800 nm which is a visible light region.
In this application example having this configuration, the optical functional film can function as, for example, an antireflection film or a UV-IR cut filter film in the visible light region.

[Application Example 6]
In the optical element according to this application example, the optical functional film is an antireflection film.
In this application example having this configuration, since the conductive layer and the non-conductive layer described above are included, the optical function film can function well as an antireflection film.

[Application Example 7]
In the optical element according to this application example, the physical film thickness of the conductive layer is larger than 5 nm and smaller than 40 nm.
In this application example having this configuration, by making the physical film thickness of the conductive layer of the antireflection film larger than 5 nm and smaller than 40 nm, light absorption can be further suppressed and light transmittance can be improved.

[Application Example 8]
A method of manufacturing an optical element according to this application example includes: a substrate; and an optical functional film disposed on the substrate and configured by alternately laminating a plurality of low refractive index layers and high refractive index layers. An optical element manufacturing method for manufacturing an optical element comprising: an outermost surface layer of the optical functional film farthest from the substrate as a first low refractive index layer; and a layer adjacent to the first low refractive index layer as a first layer. A first step of laminating the first high refractive index layer on the surface of the low refractive index layer, and laminating the first low refractive index layer on the first high refractive index layer. The second step is performed, and the first high refractive index layer laminated in the first step forms a conductive layer and a non-conductive layer, and the conductive layer is formed on the outermost layer side, When the optical functional film is a UV-IR cut filter film, the physical film thickness of the conductive layer is less than 60 nm. Characterized in that it is urchin formed.
In this application example having this configuration, as described above, dustproofness can be improved, and a method for manufacturing an optical element having excellent optical characteristics can be provided.

[Application Example 9]
An electronic apparatus according to this application example includes a light source, a dichroic prism, and an optical element disposed in an optical path between the light source and the dichroic prism, and the optical element is described in Application Example 6 or 7. It is characterized by being an optical element.
In this application example having this configuration, since the above-described optical element is provided, dust resistance can be improved, and an electronic apparatus having excellent optical characteristics can be provided.

[Application Example 10]
An electronic apparatus according to this application example includes an imaging element and an optical element disposed to face the imaging element, the optical element is the optical element described above, and the optical functional film is a UV-IR cut. It is a filter membrane.
In this application example having this configuration, since the above-described optical element is provided, dust resistance can be improved, and an electronic apparatus having excellent optical characteristics can be provided.

[Application Example 11]
An electronic apparatus according to this application example includes a light source, an objective lens, and an optical element disposed in an optical path between the light source and the objective lens, and the optical element is described in Application Example 6 or 7. It is characterized by being an optical element.
In this application example having this configuration, since the above-described optical element is provided, dust resistance can be improved, and an electronic apparatus having excellent optical characteristics can be provided.

Schematic which shows the electronic device which concerns on 1st embodiment of this invention. Sectional drawing of the optical element of 1st embodiment. The figure which shows the transmittance | permeability of the optical element of 1st embodiment, and the optical element of patent document 3. FIG. Schematic of an apparatus for forming a film on a substrate. Schematic which shows the electronic device which concerns on 2nd embodiment. Sectional drawing of the optical element of 2nd embodiment. Schematic which shows the electronic device which concerns on 3rd embodiment. The figure which shows the reflectance in the Example corresponding to the optical element of 1st embodiment, a reference example, and a comparative example. The figure which shows the transmittance | permeability in the Example corresponding to the optical element of 1st embodiment, a reference example, and a comparative example. The figure which shows the transmittance | permeability in the Example corresponding to the optical element of 2nd embodiment, a reference example, and a comparative example. The elements on larger scale of FIG.

Embodiments of the present invention will be described below with reference to the drawings. Here, in each embodiment, the same component is denoted by the same reference numeral, and description thereof is omitted or simplified.
[First embodiment]
First, a first embodiment will be described with reference to FIGS.
The first embodiment is an example in which an electronic device is a projection device such as a projector, and an optical element incorporated in the projection device is dust-proof glass.
FIG. 1 is a schematic configuration diagram of a projector.
In FIG. 1, the projector 100 includes an integrator illumination optical system 110, a color separation optical system 120, a relay optical system 130, an electro-optical device 140, and a projection lens 150.
The integrator illumination optical system 110 includes a light source 111, a first lens array 112, a second lens array 113, a polarization conversion element 114, and a superimposing lens 115. The integrator illumination optical system 110 substantially includes image forming areas of three transmissive liquid crystal panels 141 (respectively, liquid crystal panels 141R, 141G, and 141B for red, green, and blue color lights) constituting the electro-optical device 140, respectively. Illuminate uniformly.

The color separation optical system 120 includes two dichroic mirrors 121 and 122 and a reflection mirror 123. The color separation optical system 120 separates a plurality of partial light beams emitted from the integrator illumination optical system 110 by the dichroic mirrors 121 and 122 into three color lights of red (R), green (G), and blue (B). .
The dichroic mirror 121 and the reflection mirror 123 guide blue light to the transmissive liquid crystal panel 141B.
The dichroic mirror 122 guides green light out of red light and green light transmitted through the dichroic mirror 121 to the transmissive liquid crystal panel 141G through the field lens 151.
The relay optical system 130 guides the red light transmitted through the dichroic mirror 122 to the transmissive liquid crystal panel 141R through the incident side lens 131, the relay lens 133, and the reflection mirrors 132 and 134.

The electro-optical device 140 modulates an incident light beam according to image information to form a color image. The electro-optical device 140 includes transmissive liquid crystal panels 141R, 141G, and 141B, a dustproof glass 10 provided on a light incident surface of each of the transmissive liquid crystal panels 141R, 141G, and 141B, and a cross dichroic prism 142.
The dust-proof glass 10 is disposed in the optical path between the light source 111 and the cross dichroic prism 142, and the cross dichroic prism 142 synthesizes the optical image modulated for each color light to form a color image.
The projection lens 150 enlarges and projects the color image formed by the cross dichroic prism 142.

FIG. 2 is a schematic configuration diagram of the dust-proof glass 10.
In FIG. 2, a dustproof glass 10 includes a substrate 1 and an antireflection film 2 formed on the substrate 1, and is housed in a case (not shown). The substrate 1 is made of, for example, quartz, crystal, non-alkali glass or the like.
This antireflection film 2 functions in a wavelength band from 400 nm to 800 nm which is a visible light region, and a low refractive index layer 2A and a high refractive index layer 2B are alternately laminated sequentially. The outermost layer 2S farthest from the substrate 1 is the first low refractive index layer 2A. The layer adjacent to the first low refractive index layer 2A is a first high refractive index layer 2B composed of a plurality of layers.

The first high refractive index layer 2B has a conductive layer 22 as a second layer and a nonconductive layer 23 as a third layer in order from the outermost layer 2S side.
The fourth layer 24 adjacent to the first high refractive index layer 2B is the second low refractive index layer 2A, and the fifth layer 25 adjacent to the second low refractive index layer 2A is the second high refractive index layer 2B. The sixth layer 26 adjacent to the second high refractive index layer 2 </ b> B is the third low refractive index layer 2 </ b> A adjacent to the substrate 1. Since the first high refractive index layer 2B is composed of two layers, the antireflection film 2 is composed of six layers as a whole. The first high refractive index layer 2B may be composed of three or more layers.
The first low refractive index layer 2A preferably has the lowest density among the first low refractive index layer 2A, the second low refractive index layer 2A, and the third low refractive index layer 2A.

The conductive layer 22 preferably has a smaller physical film thickness than the non-conductive layer 23. That is, when the physical film thickness of the conductive layer 22 is ti and the physical film thickness of the non-conductive layer 23 is th, it is preferable that ti <th. The thickness of ti is preferably 5 nm <ti <40 nm.
Examples of the low refractive index material for forming the low refractive index layer 2A include silicon dioxide (SiO ₂ ) and magnesium fluoride (MgF ₂ ). Examples of the high refractive index material for forming the high refractive index layer 2B include titanium oxide (TiO ₂ ), ITO, IWO, SnO ₂ , zinc oxide (ZnO), cerium oxide, zirconium oxide, ditantalum pentoxide, niobium pentoxide. , Hafnium oxide (HfO ₂ ), lanthanum titanate (mixture), and the like. Among these materials, examples of the conductive material that forms the conductive layer 22 include ITO, IWO, SnO ₂ , and zinc oxide (ZnO). Examples of the nonconductive material forming the nonconductive layer 23 include TiO _2, cerium oxide, zirconium oxide, ditantalum pentoxide, niobium pentoxide, hafnium oxide (HfO ₂ ), lanthanum titanate (mixture), and the like.
The antireflection film 2 may have a dustproof layer 3 on the surface of the first low refractive index layer 2A opposite to the substrate 1.
When the antireflection film 2 has the dustproof layer 3, the surface resistance value of the antireflection film 2 is preferably 1 × 10 ⁶ Ω / cm ² or less.
Examples of the dustproof material for forming the dustproof layer 3 include fluorine-containing organosilicon compounds and magnesium fluoride.

Here, the result of comparing the light transmittance in the visible light region for the dust-proof glass 10 of the first embodiment and the optical element described in Patent Document 3 is shown in FIG.
In the optical element of Patent Document 3, as described above, since there are only two layers that function as an antireflection film, that is, one low refractive index layer and one high refractive index layer, a narrow wavelength in the visible light region. Reflection can only be prevented in the area.
On the other hand, in the dust-proof glass 10 of the first embodiment, the layer that functions as an antireflection film is composed of the three low-refractive index layers 2A and the two high-refractive index layers 2B. Reflection can be prevented.

Next, a method for manufacturing the dustproof glass 10 will be described.
FIG. 4 is a schematic view of an apparatus for forming the antireflection film 2 on the substrate 1.
In FIG. 4, the film forming apparatus includes a grounded chamber 50 and a dome 51 that is rotatably supported on a ceiling portion of the chamber 50.
The dome 51 is rotated by a motor 52 via a rotation shaft 51A provided at the center thereof. A plurality of substrates 1 to be deposited are attached to the dome 51, and a first vapor deposition source 53, a second vapor deposition source 541, and a third vapor deposition source 542 are disposed below the chamber 50 so as to face these substrates 1. Is provided. The first vapor deposition source 53 contains a low refractive index material such as SiO ₂ , the second vapor deposition source 541 contains a high refractive index material such as TiO ₂ , and the third vapor deposition source 542 contains ITO or the like. Conductive material is stored.
An ion source 55 and an electron gun 56 are disposed between the first vapor deposition source 53 and the second vapor deposition source 541. The ion source 55 assists by emitting ions. The electron gun 56 irradiates an electron beam. A monitoring device 57 is provided at the center of the dome 51. The monitoring device 57 includes an optical monitor for managing the film thickness formed on the substrate 1 and a crystal monitor for rate management.

Next, a method for forming the antireflection film 2 composed of six layers on the substrate 1 using this film forming apparatus will be described. First, after the substrate 1 is set on the dome 51, the electron beam 56 is irradiated with the electron beam 56 while the dome 51 rotates, and the SiO ₂ stored in the first evaporation source 53 and the second evaporation source 541 are stored. TiO ₂ is deposited on the substrate 1.
At this time, the ionized oxygen from the ion source 55 is accelerated and irradiated, so that the SiO ₂ third low refractive index layer 2A, the TiO ₂ second high refractive index layer 2B, and the SiO ₂ The second low refractive index layers 2A and the non-conductive layers 23 of TiO ₂ are alternately stacked.
Then, after the nonconductive layer 23 is formed, ITO accommodated in the third vapor deposition source 542 is laminated on the nonconductive layer 23 to form the conductive layer 22. Thereby, the first high refractive index layer 2B is formed (first step). Then, the outermost layer 2S of SiO ₂ is formed on the conductive layer 22 (second step).
Here, the outermost layer 2S and the conductive layer 22 are preferably formed with non-assist power (EB deposition) or low assist power (IAD) with an acceleration voltage of 300 V or more and 500 V or less (an acceleration current of 450 mA or more and 600 mA or less). .
On the other hand, the third low-refractive index layer 2A, the second high-refractive index layer 2B, the second low-refractive index layer 2A, and the non-conductive layer 23 other than the outermost layer 2S and the conductive layer 22 are 700V to 1000V. It is preferably formed with high assist power (IAD) at an acceleration voltage (acceleration current of 800 mA to 1200 mA).

After the antireflection film 2 is formed on the substrate 1, a dustproof layer 3 is formed on the antireflection film 2 as necessary.
When the dustproof layer 3 is formed, the substrate 1 on which the antireflection film 2 is formed and the vapor deposition source in which the dustproof material is stored are set inside the vacuum apparatus, and vacuum exhaust is performed. Then, the evaporation source is heated to about 600 ° C. with the temperature of the substrate 1 being 60 ° C., the dust-proof material is evaporated, and the dust-proof layer 3 is formed on the antireflection film 2.

[Effect of the first embodiment]
According to this embodiment, the following effects can be achieved.
(1) Since the conductive layer 22 is formed on the outermost layer 2S side, the charge of the outermost layer 2S can be reduced, and the dustproof property of the dustproof glass 10 can be easily improved. Further, since the outermost layer 2S is composed of the conductive layer 22 and the non-conductive layer 23, the physical film thickness of the conductive layer 22 is reduced to suppress a decrease in light transmittance and the non-conductive layer 23. As a result, the optical film thickness necessary for the first high refractive index layer 2 </ b> B can be ensured and reflection of light can be prevented.

(2) Since the antireflection film 2 is composed of a plurality of low refractive index layers 2A and a plurality of high refractive index layers 2B, the reflection of light is widely prevented in a wavelength band from 400 nm to 800 nm which is a visible light region. it can.
(3) By increasing the physical film thickness of the non-conductive layer 23, the first high refractive index layer 2B can be made difficult to peel off.
(4) By making the physical film thickness of the conductive layer 22 smaller than that of the non-conductive layer 23, the light absorption can be further suppressed and the light transmittance can be improved.
(5) By making the physical film thickness of the conductive layer 22 larger than 5 nm and smaller than 40 nm, it is possible to further suppress light absorption and improve the light transmittance.
(6) The dustproof performance can be improved by setting the outermost layer 2S to the lowest density among the three low refractive index layers 2A.
(7) By setting the surface resistance value of the antireflection film 2 to 1 × 10 ⁶ Ω / cm ² or less, the dust resistance can be further improved.

(8) Since the manufacturing method of this embodiment forms the conductive layer 22 and the nonconductive layer 23 in order from the outermost layer 2S side as the first high refractive index layer 2B, the dustproof property can be improved. The manufacturing method of the dustproof glass 10 excellent in the characteristic can be provided.
(9) Since the projector 100 includes the dust-proof glass 10, the dust-proof property can be improved and the optical characteristics are excellent.

[Second Embodiment]
Next, 2nd embodiment is described based on FIG.5 and FIG.6.
The second embodiment is an example in which an electronic device is an imaging device of a digital still camera, and an optical element incorporated in the imaging device is an optical multilayer filter.
FIG. 5 is a schematic configuration diagram of the imaging apparatus.
In FIG. 5, the imaging apparatus 200 includes an imaging module 210, a lens 220 disposed on the light incident side, and a main body 230 that performs recording / reproduction of an imaging signal output from the imaging module 210. ing. The main body unit 230 includes a signal processing unit that corrects an imaging signal, a recording unit that records the imaging signal on a recording medium such as a magnetic tape, a reproducing unit that reproduces the imaging signal, and a reproduced video. Constituent elements such as a display unit to be displayed are included.
The imaging module 210 includes an optical multilayer filter 20, an optical low-pass filter 211, an imaging device CCD (charge coupled device) 212 that electrically converts an optical image, and a drive unit 213 that drives the imaging device 212. It is configured to include.

The optical multilayer filter 20 is integrally formed with the CCD 212 on the front surface of the CCD 212 by a fixing jig 214 as a case. This optical multilayer filter 20 has not only a function of cutting IR and UV, but also a dustproof glass function of the CCD 212.
The fixing jig 214 is made of metal and is electrically connected to the optical multilayer filter 20. The fixing jig 214 is grounded (grounded) by the ground cable 215.

FIG. 6 is a schematic configuration of the optical multilayer filter 20.
In FIG. 6, the optical multilayer filter 20 includes a substrate 1 and a UV-IR cut filter film 4 formed on the substrate 1.
The UV-IR cut filter film 4 functions in a wavelength band from 400 nm to 800 nm which is a visible light region, and a plurality of low refractive index layers 2A and high refractive index layers 2B are alternately stacked. The UV-IR cut filter film 4 includes a first high refractive index layer 2B that constitutes a first low refractive index layer 2A that is the outermost layer 2S, a second conductive layer 22, and a third nonconductive layer 23. A second low refractive index layer 2A as the fourth layer 24, a second high refractive index layer 2B as the fifth layer 25, and the like. The 39th layer 239 is the 19th high refractive index layer 2B, and the 40th layer 240 is the 20th low refractive index layer 2A adjacent to the substrate 1.
Here, the second conductive layer 22 has a physical film thickness of less than 60 nm. When the physical film thickness is 60 nm or more, the light transmittance is low.
The UV-IR cut filter film 4 of the optical multilayer filter 20 may have a dustproof layer 3 on the surface opposite to the substrate 1.

Next, a method for manufacturing the optical multilayer filter 20 will be described.
This optical multilayer filter 20 is manufactured using the apparatus shown in FIG. 4 in the same manner as the dust-proof glass of the first embodiment.
First, the substrate 1 is set on the dome 51, and then the electron beam 56 is irradiated with the electron gun 56 while the dome 51 rotates, so that SiO ₂ of the first vapor deposition source 53 and TiO _{2 of} the second vapor deposition source 541 are formed. Alternatingly stacked.
Then, after the second low refractive index layer 2A of the fourth layer is laminated, TiO ₂ of the second vapor deposition source 541 is vapor deposited on the second low refractive index layer 2A, and the non-conductive layer 23 of the third layer is formed. The
Subsequently, ITO of the third vapor deposition source 542 is deposited on the third non-conductive layer 23 to form the conductive layer 22 (first step). Here, the conductive layer 22 is formed so that its physical film thickness is less than 60 nm. Thereby, the first high refractive index layer 2B is formed. Then, the outermost layer 2S of SiO ₂ is formed on the conductive layer 22 (second step).
As in the first embodiment, the outermost layer 2S and the conductive layer 22 are preferably formed with non-assist power or low assist power, and the layers 23, 2A, 2B other than the outermost layer 2S and the conductive layer 22 are It is preferably formed with high assist power.

Also in the second embodiment, the dust-proof layer 3 may be provided on the UV-IR cut filter film 4 formed on the substrate 1 as necessary. In that case, the dust-proof layer 3 is implemented in the same manner as in the first embodiment. Is done.
According to the second embodiment, there are the same effects as in the first embodiment.

[Third embodiment]
Next, a third embodiment will be described based on FIG.
The third embodiment is an example in which an electronic apparatus is an optical pickup device, and an optical element incorporated in the optical pickup device is a beam splitter.
FIG. 7 is a schematic configuration diagram of the recording / reproducing apparatus.
In FIG. 7, an optical pickup 300 irradiates three types of laser beams having different wavelengths onto an optical disc (CD301, DVD302, BD303), which is three types of optical recording media having different focal positions, and outputs predetermined signals respectively. Configured to detect.
Specifically, the optical pickup 300 includes a laser diode 310 as a laser light source that generates laser light, a collimating lens 311, a polarization beam splitter 30, a lens 313, a dichroic prism 314, and a quarter wavelength plate as an optical system related to the CD 301. 315, an aperture filter 316, an objective lens 317, and a signal detection system 318 that receives a reflected laser beam reflected from the data pit of the CD 301 and detects a signal written in the data pit by converting it into an electrical signal. Consists of.

The optical pickup 300, as an optical system related to the DVD 302, receives an LD 321 as a laser light source that generates a laser beam, a lens 322, a polarization beam splitter 30, and reflected laser light reflected from the data pit of the DVD 302 by the laser beam, The signal detection system 323 is configured to detect the signal written in the data pit by converting the signal into a signal.
The optical pickup 300 includes an LD 331 as a laser light source that generates a laser beam, a lens 332, a polarization beam splitter 30, a lens 333, a dichroic prism 334, and a reflected laser reflected from the data pit of the BD 303 as an optical system related to the BD 303. It is configured to include a signal detection system 335 for detecting a signal written in the data pit by receiving light and converting it into an electrical signal.
The schematic configuration of the polarizing beam splitter 30 is the same as that of the dust-proof glass 10 shown in FIG. 2 except for the shape of the substrate 1. That is, the polarization beam splitter 30 has a structure in which the antireflection film 2 is provided on the incident / exit surface of the prism, and the dustproof layer 3 is provided on the surface of the antireflection film 2 as necessary. Further, the method of forming the antireflection film 2 on the prism and forming the dustproof layer 3 on the antireflection film 2 is the same as in the first embodiment.
When the optical disk (CD301, DVD302, BD303) is exchanged on the surfaces of the objective lens 317, the quarter-wave plate 315, and the aperture filter 316 disposed near the portion where the optical disk is mounted, dust from outside It is also effective to dispose the dust-proof layer on the surface of the antireflection film formed on the surface because dust such as dust enters from the part and the dust easily adheres.
According to the third embodiment, there are the same effects as in the first embodiment.

Note that the present invention is not limited to the above-described embodiment, and includes the following modifications as long as the object of the present invention can be achieved.
For example, in the present invention, the optical element is not limited to the above-described configuration. For example, in the first embodiment, the optical element that is the subject of the present invention may be, for example, a polarization conversion element. Furthermore, in the second embodiment, the optical element that is the subject of the present invention may be, for example, an optical low-pass filter. In short, in the present invention, any optical element can be applied as long as an optical functional film including an antireflection film and a UV-IR cut filter film is formed on the substrate.
In the first embodiment, an antireflection film has been described as the optical function film. In the second embodiment, a UV-IR cut filter film has been described as the optical function film, but the present invention is not limited thereto. For example, the optical functional film may be a UV cut filter film, an IR cut filter film, a polarization separation film, or the like.

Examples of the present embodiment will be described.
[Optical element having antireflection film]
Reference Example 1 and Comparative Example 1 will be described from Example 1 to Example 5 corresponding to the optical element of the first embodiment of the present invention. In the vapor deposition experiment, a Shincron vapor deposition machine (trade name SID-1350) was used. Moreover, in each experiment, the conditions according to each Example, a reference example, and a comparative example on the surface of a sample of a predetermined shape, for example, a white plate glass (refractive index n = 1.51) having a diameter of 30 mm and a thickness of 0.3 mm. An antireflective film was prepared.

Example 1
In Example 1, an antireflection film as shown in Table 1 was formed on the substrate 1.
The outermost layer 2S (first layer) and the conductive layer (second layer) of the antireflection film were formed with non-assisted power (EB vapor deposition). The third to sixth layers were formed by electron beam evaporation (IAD) using ion assist with high assist power. In this case, the assist power has an acceleration voltage of 1000 V and an acceleration current of 1200 mA. Here, the physical film thickness of the conductive layer (second layer) was set to 5 nm. The design wavelength was set to 510 nm and the incident angle was set to 0 °.

(Example 2 to Example 5)
In Example 2 to Example 5, as shown in Tables 2 to 5, respectively, the optical element was the same as Example 1 except that the physical film thickness of the conductive layer was 10 nm, 20 nm, 40 nm, and 60 nm. Was made.
(Reference Example 1)
An optical element of Reference Example 1 was produced as shown in Table 6 in the same manner as in Example 1 except that the first high refractive index layer was formed only with TiO ₂ .
(Comparative Example 1)
An optical element of Comparative Example 1 was produced as shown in Table 7 in the same manner as Example 1 except that the first high refractive index layer was formed only from ITO.

(Evaluation methods)
About the optical element of an Example, a reference example, and a comparative example, the reflectance and transmittance | permeability of the light in visible region were measured. The results are shown in FIGS.

Example 1

(Example 2)

(Example 3)

Example 4

(Example 5)

(Reference Example 1)

(Comparative Example 1)

(Experimental result)
(1-1) Reflectance As shown in FIG. 8, in Examples 1 to 5, the non-conductive layer that reduces the physical film thickness of the ITO conductive layer and constitutes the first high-refractive index layer. It has been found that the reflectance is small because of the provision of.
In Comparative Example 1 in which the first high refractive index layer was formed using only ITO, the reflectivity was relatively low because the physical film thickness of the ITO conductive layer was large.
On the other hand, it was found that in Reference Example 1 in which the first high refractive index layer was formed using only TiO ₂ , the reflectance was slightly increased in the low wavelength band, and the optical characteristics were lowered.
(1-2) Transmittance As shown in FIG. 9, in Reference Example 1, since ITO was not used, the transmittance was excellent in all visible light regions. Similarly, in Example 1 to Example 5, since the ITO conductive layer was made small, it was found that the transmittance exceeded 90% and became good.
On the other hand, in Comparative Example 1, it was found that the transmittance is lowered particularly in the low wavelength band, and the optical characteristics are deteriorated.

[Optical element having UV-IR cut filter film]
Reference Example 2 and Comparative Examples 2 and 3 will be described from Example 6 to Example 9 corresponding to the optical element of the second embodiment of the present invention. In addition, regarding the vapor deposition method of each layer, it is the same as that of the above-mentioned Example 1.

(Example 6)
In Example 6, a UV-IR cut filter film as shown in Table 8 was formed on the substrate 1.
The outermost layer 2S (first layer) and the conductive layer (second layer) of the UV-IR cut filter film were formed with non-assisted power (EB vapor deposition). The layers from the third layer to the 40th layer were formed by electron beam evaporation using ion assist with high assist power. In this case, the assist power has an acceleration voltage of 1000 V and an acceleration current of 1200 mA. Here, the physical film thickness of the conductive layer (second layer) was set to 5 nm. The incident angle was set to 0 °.

(Example 7 to Example 9)
In Example 7 to Example 9, as shown in Table 9 to Table 11 respectively, optical elements were produced in the same manner as Example 6 except that the physical film thickness of the conductive layer was 10 nm, 20 nm, and 40 nm. did.
(Reference Example 2)
An optical element of Reference Example 2 was produced in the same manner as in Example 6 as shown in Table 12 except that the first high refractive index layer was formed only with TiO ₂ .
(Comparative Example 2)
An optical element of Comparative Example 2 was produced in the same manner as in Example 6 as shown in Table 13 except that the first high refractive index layer was formed only from ITO.
(Comparative Example 3)
An optical element of Comparative Example 3 was produced in the same manner as in Example 6 as shown in Table 14 except that the physical film thickness of the conductive layer was changed to 60 nm.
(Evaluation methods)
About the optical element of an Example and a comparative example, the transmittance | permeability of the light in an ultraviolet region, a visible light region, and an infrared region was measured. The results are shown in FIGS.

(Example 6)

(Example 7)

(Example 8)

Example 9

(Reference Example 2)

(Comparative Example 2)

(Comparative Example 3)

(Experimental result)
(2) Transmittance As shown in FIGS. 10 and 11, in Reference Example 2 in which the first high refractive index layer was formed using only TiO ₂ , the transmittance was high in the visible light region because ITO was not used. .
In Example 6 to Example 9, an ITO conductive layer was formed on the first high refractive index layer, and the physical film thickness of the ITO conductive layer was less than 60 nm. Therefore, as in Reference Example 1, the transmittance was high. I found out that
On the other hand, in Comparative Example 2 in which the first high refractive index layer is formed using only ITO and Comparative Example 3 in which the physical film thickness of the ITO conductive layer is 60 nm, the transmittance is low and the optical characteristics are deteriorated. I understood.

[Optical element with dustproof layer]
(Example 10)
In Example 10, a UV-IR cut filter film as in Example 6 was provided on a substrate, and a fluorine-containing organosilicon compound film was further formed on the UV-IR cut filter film.
The fluorine-containing organosilicon compound film is obtained by, for example, diluting a fluorine-containing organosilicon compound (product name KY-130) manufactured by Shin-Etsu Chemical Co., Ltd. with a fluorine-based solvent (manufactured by Sumitomo 3M: Novec HFE-7200). A solution having a concentration of 3% was prepared and impregnated with 1 g of porous ceramic pellets and dried.
The outermost layer was formed with non-assist power as shown in Table 15. The layers other than the outermost layer were formed under the conditions shown in Table 16.

(Examples 11 and 12 and Comparative Examples 4 and 5)
As shown in Table 15, the outermost layer was formed with low assist power in Examples 11 and 12, and dust-proofing was performed in the same manner as in Example 10 except that Comparative Examples 4 and 5 were formed with high assist power. An optical element having a layer was produced.

[Experimental result]
About each Example, the reference example, and the comparative example, the dustproof performance test was implemented by the (3-1) polyethylene powder method, the (3-2) Kanto loam method, and the (3-3) cotton linter method.
(3-1) Polyethylene powder method In the polyethylene powder method, a sample is dropped from above 1 cm onto polyethylene powder (manufactured by Seishin: SK-PE-20L) spread on a tray, and then slowly pulled up, the powder adhered to the sample. The amount of dust and the remaining amount are measured. As for the amount of dust, the sample with powder attached is simply paid, the surface of the sample is imaged, and the dust area is calculated by image analysis. The remaining amount is to remove the dust on the surface of the sample with powder by air blow (the distance from the sample is 3 cm, the pressure is about 50 KPa, 3 times), then image the surface of the sample and calculate the dust area by image analysis .
(3-2) Kanto Loam Method The Kanto Loam method uses powders (1, 7 kinds of JIS test powders) standardized by JIS, assuming dust on the road and in the field, and spreads on a tray. The sample is dropped on the powder, excess dust is dropped, and the amount of dust attached to the sample and the remaining amount are measured. The method for obtaining the dusting amount and the residual amount is the same as that in the polyethylene powder method.
(3-3) Cotton linter method The cotton linter method uses fiber dust called cotton linter spread on a tray for the test. The sample was dropped on the powder spread on the tray, and excess dust was dropped. Thereafter, the amount of dust adhering to the sample and the remaining amount are measured. The method for obtaining the dusting amount and the residual amount is the same as that in the polyethylene powder method.

Table 17 shows the results of the dustproof performance test carried out by these methods.
In Table 17, the results of (4-1) polyethylene powder method, (4-2) Kanto loam method and (4-3) cotton linter method are shown.
As shown in Table 17, in all of the polyethylene powder method, the Kanto loam method, and the cotton linter method, in the optical elements from Example 10 to Example 12, the dust amount and the optical elements in Comparative Examples 4 and 5 It was found that the remaining amount was small.
That is, in Example 10 to Example 12, since the SiO ₂ density of the first low refractive index layer is reduced and the conductive layer is formed as a layer adjacent to the first low refractive index layer, the dust resistance is excellent. I understood.

  The present invention can be used for optical elements incorporated in projectors, digital still camera imaging devices, optical pickups, and other electronic devices.

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Antireflection film, 2A ... Low refractive index layer, 2B ... High refractive index layer, 2S ... Outermost layer, 4 ... UV-IR cut filter film, 10 ... Dust-proof glass (optical element), 20 ... Optical Multilayer filter (optical element), 30: polarizing beam splitter (optical element), 100: projector (electronic device), 200: imaging device (electronic device), 300: optical pickup (electronic device)

Claims (11)

A substrate,
An optical functional film disposed on the substrate, wherein a plurality of low refractive index layers and high refractive index layers are alternately stacked in order,
An optical element comprising:
The outermost surface layer farthest from the substrate of the optical function film is a first low refractive index layer,
The first high refractive index layer adjacent to the first low refractive index layer is composed of a plurality of layers,
The plurality of layers are configured by arranging a conductive layer and a non-conductive layer in order from the outermost layer side,
When the optical functional film is a UV-IR cut filter film, the physical film thickness of the conductive layer is less than 60 nm. The optical element according to claim 1,
The optical element, wherein the conductive layer has a smaller physical film thickness than the non-conductive layer. The optical element according to claim 1 or 2,
The first low refractive index layer has the lowest density among the plurality of low refractive index layers. The optical element according to any one of claims 1 to 3,
An optical element having a surface resistance value of the optical functional film of 1 × 10 ⁶ Ω / cm ² or less. The optical element according to any one of claims 1 to 4,
An optical element, wherein the optical functional film functions in a wavelength band from 400 nm to 800 nm which is a visible light region. The optical element according to any one of claims 1 to 5,
An optical element, wherein the optical functional film is an antireflection film. The optical element according to claim 6,
An optical element, wherein the physical film thickness of the conductive layer is larger than 5 nm and smaller than 40 nm. A substrate,
An optical functional film disposed on the substrate and configured by alternately laminating a plurality of low refractive index layers and high refractive index layers, respectively;
An optical element manufacturing method for manufacturing an optical element comprising:
The outermost surface layer of the optical functional film farthest from the substrate is a first low refractive index layer,
A layer adjacent to the first low refractive index layer is a first high refractive index layer,
A first step of laminating the first high refractive index layer on the surface of the low refractive index layer;
A second step of laminating the first low refractive index layer on the first high refractive index layer;
Carried out
The first high refractive index layer laminated in the first step is formed by forming a conductive layer and a non-conductive layer,
The conductive layer is formed on the outermost layer side,
When the optical functional film is a UV-IR cut filter film, the optical film is formed so that a physical film thickness of the conductive layer is less than 60 nm. A light source;
A dichroic prism,
An optical element disposed in an optical path between the light source and the dichroic prism;
With
8. The electronic apparatus according to claim 6, wherein the optical element is the optical element according to claim 6. An image sensor;
An optical element disposed opposite to the imaging element;
With
The optical element is an optical element according to any one of claims 1 to 5,
The electronic functional film is a UV-IR cut filter film. A light source;
An objective lens;
An optical element disposed in an optical path between the light source and the objective lens;
With
8. The electronic apparatus according to claim 6, wherein the optical element is the optical element according to claim 6.

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