JP5486942B2 - Optical device - Google Patents

Description

  The present invention relates to an optical device that functions by combining a plurality of optical elements.

An optical device that functions by combining a plurality of optical elements is, for example, a wave plate that uses the birefringence of an optical element to convert incident light into two components, an ordinary ray and an extraordinary ray, and generate a phase difference. is there.
Here, the wavelength plate will be described by taking, as an example, a wide-band half-wave plate that converts incident light into two components of an ordinary ray and an extraordinary ray to generate a phase difference of 180 °.

A wide-band half-wave plate that is an example of an optical device is mainly composed of, for example, three optical elements including a first component, a second component, and a third component. Further, the wide band half-wave plate is arranged in a state where the principal surfaces of the optical elements are parallel.
The three optical elements are, for example, crystal plates provided in a flat plate shape having a predetermined size.
In the wideband half-wave plate, the first part and the third part are arranged at the outermost position, and the second part is arranged between the first part and the third part. Yes.
In addition, the wide-band half-wave plate receives light from the first component side, transmits light through the first component, the second component, and the third component, and from the third component side. Light is emitted.

Here, one main surface of the wideband half-wave plate is the exposed main surface of the first component, in other words, the main surface of the first component facing the main surface facing the second component side. is there. That is, one main surface of the wideband half-wave plate is a surface on which light is first incident on the optical device.
The other main surface of the wideband half-wave plate is the main surface of the first component facing the exposed main surface of the third component, in other words, the main surface facing the second component side. . That is, the other main surface of the wide band half-wave plate is a surface from which light is finally emitted from the optical device.

  A wide-band half-wave plate, which is an example of an optical device, converts incident light into two components of an ordinary ray and an extraordinary ray by transmitting light from one principal surface to the other principal surface. A phase difference of ° is generated (for example, see Patent Document 1).

In such an optical device, for example, three optical elements are bonded by an organic adhesive. Therefore, in such an optical device, an adhesive layer made of an organic adhesive is provided between the first component and the second component, the first component and the second component are joined, and the second component and An adhesive layer made of an organic adhesive is provided between the third component and the second component and the third component are joined.
That is, in such an optical device, an adhesive layer made of an organic adhesive is provided between adjacent optical elements, and the adjacent optical elements are joined.
Further, the optical device is provided with antireflection films on both main surfaces.
The antireflection film is provided to suppress the amount of light reflected at the interface between the optical element and the air when light travels from the air layer to the optical element or when light travels from the optical element to the air layer. It has been.
The adhesive layer made of an organic adhesive has a refractive index close to that of the first component, the second component, and the third component, that is, the optical element. For this reason, light does not reflect at the interface between the adhesive layer made of an organic adhesive and the optical element (see, for example, Patent Document 2).

Further, the optical device may be fixed by a holder so that the principal surfaces of the three optical elements are in a parallel state, for example.
In such an optical device, an air space is formed between adjacent optical elements. Therefore, in order to suppress the amount of light reflected at the interface between the air space and the optical element, It is necessary to provide an antireflection film at the interface.

Japanese Patent Laid-Open No. 2010-8808 Japanese Patent Laid-Open No. 2008-51998

However, in the conventional optical device, an adhesive layer made of an organic adhesive is provided between adjacent optical elements, and the adjacent optical elements are joined. That is, the conventional optical device has a structure in which incident light is transmitted through an adhesive layer made of a plurality of optical elements and an organic adhesive.
For this reason, when transmitting light in the ultraviolet or infrared region, conventional optical devices absorb the light in the ultraviolet or infrared region inside the adhesive layer made of organic adhesive and transmit the light in the ultraviolet or infrared region. There is a fear that it cannot be made.
In addition, when provided in a high temperature atmosphere, or in a high humidity atmosphere, or when irradiated with a laser, the conventional optical device has an adhesive layer made of an organic adhesive that changes in quality. Light may be absorbed inside the layer and light may not be transmitted.
In other words, the conventional optical device has an adhesive layer made of an organic adhesive between adjacent optical elements and joins the adjacent optical elements, so there is a possibility that light cannot be transmitted. There is a possibility that it cannot be used as a device.

Further, in the conventional optical device, a plurality of optical elements are provided in each holder so that their main surfaces are parallel to each other. For this reason, in the conventional optical device, since an air space is formed between adjacent optical elements, an antireflection film is provided on the main surface of the optical element in contact with the air space.
That is, when the number of optical elements is large, the conventional optical device is reflected by each antireflection film even though the conventional optical device can suppress the amount of light reflected by each antireflection film. Accumulating light reduces the light transmitted through the optical device and may reduce the transmittance.

  Therefore, the present invention has an object to provide an optical device that can bond an optical element without using an adhesive layer made of an organic adhesive, and does not require an antireflection film and a holder twice as many as the optical element. To do.

In order to solve the above-described problem, a plurality of optical elements provided at positions where main surfaces thereof are parallel to each other and the adjacent optical elements provided at positions where light is not transmitted are adjacent to each other. And an adhesive layer made of a metal or semiconductor material that forms an air space between the optical elements, and the total thickness of the adhesive layer is 10 nm or less .

Such an optical device includes a plurality of optical elements provided at positions where their main surfaces are parallel to each other, and an adhesive layer that joins adjacent optical elements made of a metal or a semiconductor material. Further, such an optical device is provided between adjacent optical elements at a position where the adhesive layer is not transmitted when the adhesive layer is used as an optical device, and an air space is provided between the adjacent optical elements. Is formed.
Accordingly, when used as an optical device, such an optical device transmits light through a plurality of optical elements and air spaces without transmitting through an adhesive layer made of an organic adhesive.
For this reason, when used as an optical device that transmits light in the ultraviolet region or infrared region, such an optical device is not provided with an adhesive layer made of an organic adhesive. Does not penetrate through the adhesive layer. Therefore, such an optical device can transmit light in the ultraviolet region and infrared region.
In addition, when provided in a high temperature atmosphere, when provided in a high humidity atmosphere, or when irradiated with a laser, such an optical device is provided with an adhesive layer made of an organic adhesive. Since no optical element is bonded, light can be transmitted.
That is, such an optical device can be used as an optical device because it can join optical elements and transmit light without providing an adhesive layer made of an organic adhesive.

Further, in such an optical device, an adhesive layer is provided between adjacent optical elements at a position where light is not transmitted, and an air space is formed between the adjacent optical elements. In such an optical device, the total thickness of the adhesive layer is 10 nm or less.
In such an optical device, adjacent optical elements are joined by an adhesive layer, and therefore the thickness of the adhesive layer can be regarded as the interval between adjacent optical elements, that is, the thickness of the air space. it can.
In such an optical device, since the total thickness of the adhesive layer is 10 nm or less, the total thickness of the air space inside the optical device is 10 nm or less. For this reason, since such an optical device can suppress the amount of light reflected at the interface between the air space and the optical element, it is not necessary to provide an antireflection film at the interface between the air space and the optical element.
Accordingly, such an optical device eliminates the need to provide an antireflection film on the optical element in contact with the air space unlike the conventional optical device, and therefore suppresses a decrease in transmittance as compared with the conventional optical device. Can do.

It is sectional drawing which shows an example of the optical device which concerns on embodiment of this invention. It is the transmittance | permeability characteristic view of the ultraviolet region which shows the relationship between the wavelength of the optical device which concerns on embodiment of this invention, and the transmittance | permeability.

  Next, the best mode for carrying out the present invention will be described. In each drawing, the state of each component is exaggerated for easy understanding.

An optical device according to an embodiment of the present invention will be described.
The optical device 100 has a structure that transmits light from one main surface to the other main surface.
Further, as shown in FIG. 1, the optical device 100 mainly includes a plurality of optical elements, for example, three optical elements 110, 120, and 130.
Further, in the optical device 100, as shown in FIG. 1, connection films having predetermined thicknesses t12 and t23 are provided between adjacent optical elements 110, 120, and 130 to form air spaces K12 and K23. .
Further, the optical device 100 is provided with antireflection films H on both main surfaces.
Further, the optical device 100 is provided with a predetermined other optical element 120 between two predetermined optical elements 110 and 130, and is disposed at a position where the main surfaces of the respective optical elements 110, 120, and 130 are parallel to each other. ing.
Further, the optical device 100 is provided between the optical elements 110 and 120 where the adhesive layer S12 is adjacent, and is provided between the optical elements 120 and 130 where the adhesive layer S23 is adjacent.

Here, one main surface of the optical device 100 is the main surface of the optical element 110 facing the main surface facing the optical element 120 side, in other words, the exposed main surface of the optical element 110 arranged on the outermost side. is there. That is, one main surface of the optical device 100 is a surface on which light is first incident on the optical device 100.
The other main surface of the optical device 100 is the main surface of the optical element 130 facing the main surface facing the optical element 120 side, in other words, the exposed main surface of the optical element 130 arranged on the outermost side. . That is, the other main surface of the optical device 100 is a surface from which light is finally emitted from the optical device 100.

  The optical elements 110, 120, and 130 are made of, for example, quartz and have a predetermined thickness.

For the adhesive layer S12, a metal or a semiconductor material is used.
Here, for example, titanium is used for the adhesive layer S12.
Further, the adhesive layer S12 is provided at a position where light is not transmitted when used as the optical device 100, for example, by anodic bonding.
The adhesive layer S12 is provided between the adjacent optical elements 110 and 120, and forms an air space K12 between the adjacent optical elements 110 and 120.
Here, the adhesive layer S12 is provided in an annular shape, for example, along the edge of the main surface of the optical element 120 facing the optical element 110 side.
Further, the adhesive layer S12 has a thickness t12 of 5 nm, for example.

The adhesive layer S23 is made of a metal or a semiconductor material.
Here, for example, titanium is used for the adhesive layer S23.
In addition, the adhesive layer S <b> 23 is provided, for example, by anodic bonding at a position where light is not transmitted when used as the optical device 100.
The adhesive layer S23 is provided between the adjacent optical elements 120 and 130, and forms an air space K23 between the adjacent optical elements 120 and 130.
Here, the adhesive layer S23 is provided in a ring shape along the edge of the main surface of the optical element 120 facing the optical element 130 side, for example.
The adhesive layer S23 has a thickness t12 of 5 nm, for example.

Here, the sum of the thickness t12 of the adhesive layer S12 and the thickness t23 of the adhesive layer S23, that is, the total thickness of the adhesive layers S12 and S23 is 10 nm or less.
When the sum of the thickness t12 of the adhesive layer S12 and the thickness t23 of the adhesive layer S23, that is, the total thickness of the adhesive layers S12 and S23 is 10 nm, the optical device 100 has an ultraviolet region, that is, a wavelength of 300, as shown in FIG. It can transmit 98% or more of light of ˜400 nm.
When the total thickness of the adhesive layers S12 and S23 is larger than 10 nm, for example, when the total thickness of the adhesive layers S12 and S23 is 30 nm, the optical device 100 has an ultraviolet region, that is, a wavelength of 300 to 300, as shown in FIG. The light of 400 nm cannot be transmitted 98% or more.
Further, as shown in FIG. 2, the conventional optical device provided with the adhesive layer made of an organic adhesive cannot transmit 98% or more of light in the ultraviolet region, that is, the wavelength of 300 to 400 nm.
Therefore, the optical device 100 according to the embodiment of the present invention can be considered that the air spaces K12, K23 are not formed by setting the total thickness of the adhesive layers S12, S23 to 10 nm or less. The influence of the difference in refractive index between K23 and the optical elements 110, 120, and 130 can be suppressed. For this reason, in such an optical device, since the total thickness of the adhesive layers S12 and S23 is 10 nm or less, it is possible to transmit 98% or more of light in the ultraviolet region, that is, light having a wavelength of 300 to 400 nm. .

  The antireflection film H is provided to suppress the amount of light reflected at the interface between the optical element 110 and the air on the one principal surface side of the optical device 100. The antireflection film H is provided to suppress the amount of light reflected at the interface between the optical element 130 and the air on the other main surface side of the optical device 100.

Such an optical device 100 includes a plurality of optical elements 110, 120, and 130 having principal surfaces provided in parallel positions, and adhesive layers S12 and S23 made of a metal or a semiconductor material. Further, such an optical device 100 is provided between the adjacent optical elements 110 and 120 at a position where the adhesive layer S12 does not transmit light when used as the optical device 100, and an air space K12 is formed. In addition, when the adhesive layer S23 is used as the optical device 100, the air space K23 is formed by being provided between the adjacent optical elements 120 and 130 at a position that does not transmit light.
Therefore, when used as the optical device 100, such an optical device 100 transmits light through the plurality of optical elements 110, 120, and 130 and the air spaces K12 and K23 without passing through an adhesive layer made of an organic adhesive. .
For this reason, when used as an optical device 100 that transmits light in the ultraviolet region or infrared region, such an optical device 100 is not provided with an adhesive layer made of an organic adhesive, and therefore, an organic adhesive as in a conventional optical device is provided. It does not permeate the inside of the adhesive layer made of an agent. Accordingly, such an optical device 100 can transmit light in the ultraviolet region and infrared region.
In addition, when provided in a high temperature atmosphere, when provided in a high humidity atmosphere, or when irradiated with a laser, such an optical device 100 is provided with an adhesive layer made of an organic adhesive. Since the optical elements 110, 120, and 130 are not joined, light can be transmitted.
That is, such an optical device 100 can be used as the optical device 100 because the optical elements 110, 120, and 130 can be bonded and light can be transmitted without providing an adhesive layer made of an organic adhesive.

In the optical device 100 according to the embodiment of the present invention, the adhesive layer S12 is provided between the adjacent optical elements 110 and 120 at a position where light is not transmitted, and the air is interposed between the adjacent optical elements 110 and 120. A space K12 is formed. In the optical device 100 according to the embodiment of the present invention, the adhesive layer S23 is provided between the adjacent optical elements 120 and 130 at a position where light is not transmitted, and the air is interposed between the adjacent optical elements 120 and 130. A space K23 is formed. In such an optical device 100, the total thickness of the adhesive layers S12 and S23 is 10 nm or less.
In the optical device 100 according to the embodiment of the present invention, the adjacent optical elements 110 and 120 are bonded by the adhesive layer S12, and the adjacent optical elements 120 and 130 are bonded by the adhesive layer S23. ing. That is, in such an optical device 100, the thickness of the adhesive layer S12 can be regarded as the distance between the adjacent optical elements 110 and 120, that is, the thickness of the air space K12, and the thickness of the adhesive layer S23 is adjacent to the optical device 100. It can be regarded as the distance between the elements 120 and 130, that is, the thickness of the air space K23.
In such an optical device 100, since the total thickness of the adhesive layers S12, S23 is 10 nm or less, the total thickness of the air spaces K12, K23 inside the optical device 100 is 10 nm or less. For this reason, since such an optical device can suppress the amount of light reflected at the interface between the air spaces K12, K23 and the optical elements 110, 120, 130, the air spaces K12, K23 and the optical elements 110, 120. , 130 is not required to be provided with an antireflection film H.
Accordingly, the optical device 100 does not need to be provided with the antireflection film H on the optical elements 110, 120, and 130 that are in contact with the air spaces K12 and K23 as in the conventional optical device. In comparison, a decrease in transmittance can be suppressed.

Further, in such an optical device 100, an adhesive layer made of a metal or a semiconductor material is provided between adjacent optical elements 110, 120, and 130, and air spaces K12 and K23 are formed.
That is, since the optical device 100 is provided with the optical elements 110, 120, and 130 without using a holder as in the conventional optical device, the size can be reduced by the amount of the holder. For this reason, such an optical device 100 can be easily reduced in size compared with the conventional optical device.

  In addition, although the case where an optical element consists of quartz is demonstrated, if it has the function as an optical element, glass may be sufficient, for example.

  In addition, although the case where three optical elements are provided is described, if there are a plurality of optical elements, for example, four optical elements may be provided. Two may be sufficient.

  Although the case where the adhesive layer is made of titanium has been described, it may be made of a metal or a semiconductor material such as tantalum, chromium, aluminum, or silicon as long as adjacent optical elements can be bonded. . Moreover, as long as it can join, the alloy which consists of a some material may be sufficient.

  The adhesive layer is provided by anodic bonding. However, for example, a plating method may be used as long as adjacent optical elements can be bonded.

  In addition, although the case where two adhesive layers are provided is described, if the total thickness of the adhesive layers is 10 nm or less, for example, three adhesive layers may be provided. Moreover, if the thickness of the adhesive layer is 10 nm or less, for example, one adhesive layer may be provided.

  In addition, although the case where the optical device is a wide-band half-wave plate has been described, an optical device combining a plurality of optical elements may be, for example, a quarter-wave plate or a low-pass filter.

100 Optical device 110, 120, 130 Optical element H Antireflection film S12, S23 Adhesive layer K12, K23 Air space t12, t23 Thickness of adhesive layer

Claims (1)

A plurality of optical elements provided at positions where the respective principal surfaces are parallel;
An adhesive layer made of a metal or a semiconductor material that is provided between the adjacent optical elements at a position where light is not transmitted and forms an air space between the adjacent optical elements;
Equipped with a,
An optical device, wherein the total thickness of the adhesive layer is 10 nm or less .

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