JP2006220690A - Optical element, liquid crystal device and liquid crystal projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device capable of more effectively using incident light and to provide a liquid crystal device including the optical element, and a liquid crystal projector incorporating the liquid crystal device. <P>SOLUTION: The optical element includes an optical component having a substrate, a joint face directly joined to the substrate, and an optical face different from the joint face, wherein the optical face is provided with an anti-reflection film. The optical element including the substrate and the optical component having the optical face further includes the antireflection film provided on the optical component, and the antireflection film has the joint face directly joined to the substrate. In the optical element including the optical component having a first refracting face, the optical component further includes a second refracting face corresponding to the first refracting face. The first refracting face has refracting power with a sign that is opposite to the sign of the refracting power of the second refracting face corresponding to the first refracting face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element, a liquid crystal device, and a liquid crystal projector.

  In general, a liquid crystal projector is a light source, a liquid crystal device that forms an image projected on a screen using liquid crystal, a relay optical system that irradiates the liquid crystal device with light emitted from the light source, a liquid crystal device that is transmitted through or reflected from the liquid crystal device. In addition, a projection optical system that projects light having image information formed on the liquid crystal device onto a screen is provided. The liquid crystal device has a liquid crystal phase including liquid crystal molecules formed on the substrate and the substrate, and forms a desired image in the liquid crystal phase by controlling the alignment of the liquid crystal molecules included in the liquid crystal phase.

  Here, in order to improve the brightness and contrast of the image projected on the screen by the liquid crystal projector, it is desired to efficiently irradiate the liquid crystal phase of the liquid crystal device with the light emitted from the light source. For this reason, the liquid crystal device is provided with, for example, an optical element for condensing light from the light source into the liquid crystal phase.

  FIG. 10 is a side view showing an example of a conventional liquid crystal device including an optical element for condensing light from a light source into a liquid crystal phase.

  As shown in FIG. 10, the conventional liquid crystal device is provided on a liquid crystal substrate 202, a liquid crystal phase 204 provided on the liquid crystal substrate, an optical element substrate 104 provided on the liquid crystal phase 204, and an optical element substrate 104. It has a microlens array 102 as an optical element. As shown in FIG. 10, when the conventional liquid crystal device is a transmissive liquid crystal device that transmits light from a light source, a liquid crystal substrate 202, a liquid crystal phase 204, an optical element substrate 104, and a microlens. All of the array 102 can transmit light from the light source. The microlens array 102 includes a plurality of identical microlenses that are equally arranged in two dimensions. The microlens of the microlens array 102 has a spherical surface on the light incident side from the light source and a flat surface on the optical element substrate 104 side. That is, the microlens of the microlens array 102 is a plano-convex lens. On the other hand, the liquid crystal phase 204 includes a plurality of liquid crystal molecules 206. The liquid crystal phase 204 is provided with a liquid crystal driving circuit 208 for applying a voltage to the liquid crystal molecules 206 to control the alignment of the liquid crystal molecules 206. The liquid crystal driving circuit 208 includes a thin film transistor (TFT) and a wiring connected to the TFT. Further, the liquid crystal driving circuit 208 is located between the plurality of lenses in the microlens array 102.

  The light from the light source is substantially parallel light as indicated by the solid arrow in FIG. 10 and is incident on the microlens array 102 substantially perpendicularly. The microlens of the microlens array 102 is designed to focus the parallel light emitted from the light source into the liquid crystal phase so that the light incident on the liquid crystal device does not hit the liquid crystal driving circuit 208 provided in the liquid crystal phase 204. Is done. Therefore, the light incident as parallel light is converged by the plano-convex lens of the microlens array 102, condensed in the liquid crystal phase, and emitted from the liquid crystal phase as divergent light. At this time, the liquid crystal driving circuit 208 is controlled by a signal from an external controller, and the orientation of the liquid crystal molecules 206 is controlled. Since the liquid crystal molecules 206 transmit light in a specific orientation and absorb light in another orientation, desired image information is given to light emitted from the liquid crystal device by controlling the orientation of the liquid crystal molecules 206. be able to. The light with the image information emitted from the liquid crystal device is collimated again by a collimator lens (not shown) and enters the projection lens as parallel light. And the light to which image information was given is projected on a screen by a projection lens.

  However, in the conventional liquid crystal device, since the light from the light source is focused on a specific part of the liquid crystal phase by the lens of the micro lens array 102 as an optical element, the numerical aperture of the micro lens of the micro lens array 102 is increased. The energy concentrated on a specific part of the liquid crystal phase increases. As a result, when the durability of the liquid crystal phase is not sufficient, the liquid crystal molecules contained in a specific portion of the liquid crystal phase are deteriorated by the light focused by the microlens of the microlens array 102, and the life of the liquid crystal phase is shortened. There is. Accordingly, in order to maintain the life of the liquid crystal phase, it is necessary to reduce the numerical aperture of the microlens of the microlens array 102 to reduce the energy concentrated in the liquid crystal phase below the optimum value, and enter the optical element. Cannot be used effectively enough.

  Further, the light emitted from the lamp as the light source is not completely parallel light even if it passes through a homogenizer for collimating the light from the lamp, and as shown by the broken line arrows in FIG. There is also light that is incident on the microlens array 102 in the device at an angle (eg, at an incident angle of 6-7 ° or less). When such obliquely incident light is incident on the microlens array 102, the path of the obliquely incident light is deflected by the microlens of the microlens array 102 and mixed with the light passing through adjacent pixels. There is also. As described above, when light is incident obliquely on the microlens array 102 and light is mixed in adjacent pixels, color mixture of projected images, unevenness of luminance, and reduction in contrast are caused. An image may not be obtained. In particular, when increasing the numerical aperture of the microlens in the microlens 102 as an optical element and concentrating more light emitted from the light source onto the liquid crystal phase, the microlens of the microlens array 102 is obliquely inclined. Incident light increases and light that mixes with light transmitted through adjacent lenses increases. Therefore, in order to reduce the light mixed with the light transmitted through the adjacent lens, the numerical aperture of the microlens of the microlens array 102 is reduced, and the light obliquely incident on the microlens of the microlens array 102 is reduced. Therefore, the light incident on the optical element cannot be used sufficiently effectively.

  Furthermore, since the light incident obliquely on the microlens is emitted obliquely from the liquid crystal device, the light emitted obliquely may not be sufficiently collimated by the collimator lens. As a result, light mixing through adjacent pixels may occur on the screen, resulting in color mixing of the projected image, non-uniform brightness, and reduced contrast, resulting in failure to obtain the desired image. . That is, also in this case, the optical element used in the conventional liquid crystal device has a problem that the light incident on the optical element cannot be used sufficiently effectively. Further, even if the light emitted obliquely from the liquid crystal device can be sufficiently collimated by the collimator lens, the design of the collimator lens becomes complicated.

  Next, another example of an optical element for condensing light from a light source in a liquid crystal device into a liquid crystal phase is, for example, an optical element for a liquid crystal device disclosed in Patent Document 1. FIG. 11 shows an example of a conventional optical element for a liquid crystal device disclosed in Patent Document 1.

As shown in FIG. 11, the conventional optical element for a liquid crystal device disclosed in Patent Document 1 includes a microlens array 302 and a cover glass 304. Here, the microlens array 302 and the cover glass 304 are made of the same transparent glass material (for example, quartz glass), and the upper surface of the microlens of the microlens array 302 and the surface of the cover glass are flat. . The microlens array 302 and the cover glass 304 are bonded by directly bonding the upper part of the microlens array 302 and the surface of the cover glass 304 to each other. In such an optical element for a liquid crystal device disclosed in Patent Document 1, it is not necessary to use a resin adhesive having lower heat resistance than glass for bonding the microlens array 302 and the cover glass 304. An optical element for a liquid crystal device having high heat resistance can be obtained. However, Patent Document 1 does not disclose a specific method of direct bonding in which the upper part of the microlens array 302 and the surface of the cover glass 304 are bonded. The light emitted from the light source passes through the optical element and is applied to the liquid crystal device. However, the light passing through the upper plane of the microlens of the microlens array 302 is not refracted, and the upper part of the microlens. The light passing through the curved surface outside the plane is refracted and collected toward the liquid crystal device. However, even when the conventional optical element for a liquid crystal device disclosed in Patent Document 1 is used, utilization of light incident on the optical element is still insufficient.
International Publication No. 2004/036296 Pamphlet

  An object of the present invention is to provide an optical element capable of more effectively using incident light, a liquid crystal device including the optical element, and a liquid crystal projector including the liquid crystal device.

  The invention according to claim 1 is an optical element including a substrate, a bonding surface directly bonded to the substrate, and an optical component having an optical surface different from the bonding surface, and the optical surface is provided with an antireflection film. It is characterized by.

  According to a second aspect of the present invention, in the optical element according to the first aspect, the substrate and the optical component are independently formed of silicon oxide, silicate, silicate glass, and borosilicate glass. The material is selected from the group consisting of: and the direct bonding is a glass direct bonding.

  According to a third aspect of the present invention, in the optical element according to the first or second aspect, the bonding surface is a substantially flat surface.

  Invention of Claim 4 is an optical element as described in any one of Claims 1 thru | or 3. The said optical component further includes the surface joined to the said board | substrate different from the said joining surface, It is characterized by the above-mentioned. To do.

  According to a fifth aspect of the present invention, in the optical element according to any one of the first to fourth aspects, the space between the substrate and the antireflection film is a vacuum or made of air. Features.

  According to a sixth aspect of the present invention, in the optical element according to any one of the first to fifth aspects, the optical component includes a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens. Including more selected optical components.

  The optical element including an optical component having a substrate and an optical surface further includes an antireflection film provided on the optical component, and the antireflection film is directly bonded to the substrate. It has the joining surface to do.

  The invention according to claim 8 is the optical element according to claim 7, wherein the substrate and the antireflection film are independently silicon oxide, silicate, silicate glass, and borosilicate glass. The material is selected from the group consisting of: and the direct bonding is a glass direct bonding.

  According to a ninth aspect of the present invention, in the optical element according to the seventh or eighth aspect, the bonding surface is substantially flat.

  According to a tenth aspect of the present invention, in the optical element according to any one of the seventh to tenth aspects, the antireflection film further includes a surface that is bonded to the substrate different from the bonded surface. To do.

  According to an eleventh aspect of the present invention, in the optical element according to any one of the seventh to eleventh aspects, a space between the substrate and the antireflection film is a vacuum or made of air. Features.

  A twelfth aspect of the present invention is the optical element according to any one of the seventh to eleventh aspects, wherein the optical component includes a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens. Including more selected optical components.

  The invention according to claim 13 is an optical element including an optical component having a first refractive surface, wherein the optical component further includes a second refractive surface corresponding to the first refractive surface, The first refracting surface has a refracting power having a sign opposite to that of the second refracting surface corresponding to the first refracting surface.

  According to a fourteenth aspect of the present invention, in the optical element according to the thirteenth aspect, the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface. It is characterized by being equal.

  A fifteenth aspect of the present invention is the optical element according to the thirteenth or fourteenth aspect, further comprising a substrate, wherein the optical component has a bonding surface that directly bonds to the substrate.

  According to a sixteenth aspect of the present invention, in the optical element according to the fifteenth aspect, the substrate and the optical component are independently formed of silicon oxide, silicate, silicate glass, and borosilicate glass. The material is selected from the group consisting of: and the direct bonding is a glass direct bonding.

  According to a seventeenth aspect of the present invention, in the optical element according to any one of the thirteenth to sixteenth aspects, the space between the substrate and the optical component is a vacuum or made of air. Features.

  According to an eighteenth aspect of the present invention, in the optical element according to any one of the thirteenth to seventeenth aspects, the optical component is bonded to the substrate via an adhesive.

  According to a nineteenth aspect of the present invention, in the optical element according to any one of the thirteenth to eighteenth aspects, the optical component is a third diffractive surface different from the first refracting surface and the second refracting surface. A fourth surface corresponding to the surface and the third surface is further included, and the third surface and the fourth surface are substantially flat.

  The invention according to claim 20 is the optical element according to any one of claims 13 to 19, wherein the optical component comprises a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens. It is characterized by including the component selected more.

  A twenty-first aspect of the present invention is a liquid crystal device including the optical element according to any one of the first to twenty-first aspects and a liquid crystal.

  According to a twenty-second aspect of the present invention, in the liquid crystal projector, the liquid crystal device according to the twenty-first aspect is included.

  ADVANTAGE OF THE INVENTION According to this invention, the optical element which can utilize incident light more effectively, the liquid crystal device containing this optical element, and the liquid crystal projector containing this liquid crystal device can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings.

  According to a first aspect of the present invention, there is provided an optical element including a substrate, a bonding surface directly bonded to the substrate, and an optical component having an optical surface different from the bonding surface, and an optical surface provided with an antireflection film. It is an element.

  In the optical element according to the first aspect of the present invention, since the antireflection film is provided on the optical surface, reflection of light by the optical surface is reduced, and light incident on the optical element is used more effectively. can do. In particular, the reflection of light onto the substrate by the optical surface can be reduced, and the proportion of light transmitted through the optical component can be improved. Here, the antireflection film includes not only a film that completely prevents reflection of light on the optical surface, but also a film that partially prevents (reduces) reflection of light on the optical surface. Thus, according to the first aspect of the present invention, it is possible to provide an optical element that can more effectively use incident light.

  In the optical element according to the first aspect of the present invention, since the optical component has a joint surface that is directly bonded to the substrate, the substrate and the optical component are directly connected to each other without using an adhesive such as a resin. Can be joined. In this way, since the substrate and the optical component are directly joined without using a resin adhesive having a relatively large thermal expansion coefficient, the durability or heat resistance of the optical element against temperature change is improved, and the temperature change Deformation of the optical element can be suppressed. In addition, since the resin adhesive is not used, the optical element according to the first aspect of the present invention does not deteriorate over time even when used for a long period of time. No yellowing). That is, an optical element that is stable over time can be provided. Furthermore, by directly bonding the substrate and the optical component without using an adhesive, the optical component can be positioned, bonded, and fixed to the substrate with high accuracy.

  The antireflection film may be a single layer film or a multilayer film including two or more layers.

  In the first aspect of the present invention, preferably, the substrate and the optical component are each independently made of a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass. Including and direct bonding is glass direct bonding.

  Here, examples of the silicon oxide include optical glasses such as quartz, Pyrex (registered trademark) glass, Tempax (trade name) glass, and low expansion glass such as Neoceram (trade name). If the substrate and the optical component each independently comprise a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass, ie, the substrate and optical component When both are made of a material including Si—O bonds, the substrate and the optical component can be directly bonded to each other through the bonding surface of the optical component.

  As a method of direct glass bonding, 1% hydrofluoric acid is applied to the bonding surface of the optical component by the tampo method, the substrate and the optical component are brought into contact with each other through the bonding surface, and the bonding surface of the substrate and the optical component And a method of heating at about 60 ° C. for 1 hour while applying a pressure of about 1.0 MPa.

  In addition, since the substrate and optical components are directly bonded to glass without using a resin adhesive having a large thermal expansion coefficient compared to glass, the durability or heat resistance of the optical element against temperature changes is improved. The deformation of the optical element due to temperature change can be suppressed. Furthermore, since the optical element which is the first aspect of the present invention is composed of a chemically stable inorganic material as compared with the resin, it is possible to provide an optical element that is stable over time.

  The optical surface may be a convex or concave spherical surface, a convex or concave aspheric surface, or a convex or concave anamorphic surface.

  In the first aspect of the present invention, preferably, the joining surface is substantially flat.

  The bonding surface of the optical component and the surface of the substrate corresponding to the bonding surface of the optical component have substantially the same shape in order to bond directly to each other. Therefore, the joint surface of the optical component and the surface of the substrate corresponding to the joint surface of the optical component may be substantially the same curved surface (spherical surface, aspherical surface, etc.), for example. However, when the joint surface of the optical component and the surface of the substrate corresponding to the joint surface of the optical component are substantially flat, the configuration of the substrate and the like can be simplified. Here, “substantially” means the degree to which direct bonding can be achieved. Further, when the bonding surface is substantially flat, parallel light that enters the optical element and reaches the bonding surface can be emitted as parallel light from the bonding surface. On the other hand, parallel light that enters the optical element and reaches the optical surface can be emitted from the joint surface as convergent light or divergent light.

  In the first aspect of the present invention, preferably, the optical component further includes a surface to be bonded to the substrate, which is different from the above-described bonding surface.

  When the optical component further includes a surface that is different from the above-described bonding surface and is bonded to the substrate, the bonding strength between the substrate and the optical component can be further increased. Moreover, the surface of the optical component to be bonded to the substrate, which is different from the bonding surface described above, may be bonded to the corresponding surface of the substrate using an adhesive, or may be directly bonded like glass direct bonding. . Further, the surface of the optical component to be bonded to the substrate, which is different from the bonding surface described above, may be a curved surface, like the bonding surface, but is preferably substantially flat.

  In the first aspect of the present invention, the space between the substrate and the antireflection film is preferably a vacuum or made of air.

  If the space between the substrate and the antireflective coating provided on the optical surface of the optical component is vacuum or air, that is, filled with a medium having a refractive index of 1, the optical configuration Since the difference between the component material and the refractive index of vacuum or air is large, the design of the optical surface of the optical component can be facilitated. For example, when the optical component is a lens (array), the curvature of the lens surface as the optical surface can be reduced. In addition, when the space between the antireflection film provided on the optical surface of the substrate and the optical component is air, the outside air can pass through the space between the substrate and the antireflection film, so that the optical element Is used together with a device that generates heat, the heat applied to the optical element can be easily released, and the cooling efficiency of the optical element can be increased. On the other hand, when the space between the antireflection film provided on the optical surface of the substrate and the optical component is a vacuum, an optical element having high heat insulation can be provided.

  In order to make the space between the substrate and the antireflection film vacuum (or air), the substrate and the optical component are directly bonded in vacuum (or air).

  In the first aspect of the present invention, preferably, the optical component includes an optical component selected from the group consisting of a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens.

  The lens (array) forms a layer of photosensitive material (photoresist) on a plane-parallel plate of optical glass material, and performs a density distribution mask designed for the desired lens (array) and exposure, development, and curing processes. Using a photolithographic process including, forming a three-dimensional initial structure of the photosensitive material with the desired lens shape, and transferring the three-dimensional initial structure of the photosensitive material to the optical glass material by etching It is produced by doing. The density distribution mask can be obtained by, for example, a method disclosed in JP-A-7-230159.

  Here, an optical component as a lens (array) having a practically cemented surface is produced as follows. When the form of the three-dimensional initial structure of the photosensitive material is transferred to the optical glass material by etching, the portion corresponding to the substantially planar joining surface in the three-dimensional initial structure of the photosensitive material is the optical glass material. The etching is stopped before being transferred. That is, only the portion corresponding to the optical surface in the three-dimensional initial structure of the photosensitive material is transferred to the optical glass material, and the portion corresponding to the substantially planar joining surface in the three-dimensional initial structure of the photosensitive material is Instead of being transferred to the optical glass material, it remains in the optical glass material, and the plane shape of the plane parallel plate is maintained. Then, the portion of the three-dimensional initial structure of the photosensitive material remaining without being transferred to the optical glass is removed from the optical glass material. In this way, it is possible to obtain an optical component as a lens (array) having a substantially cemented surface.

  Here, the antireflection film provided on the optical surface of the optical component, not provided on the bonding surface of the optical component, is produced as follows. Before removing the portion of the three-dimensional initial structure of the photosensitive material, which remains without being transferred to the optical glass, corresponding to the substantially planar joining surface from the optical glass material, the optical glass material is subjected to a thin film formation process. An antireflection film is formed on the entire surface of the film. In other words, the optical surface of the optical glass material formed by transferring the form of the three-dimensional initial structure of the photosensitive material, and the three-dimensional initial structure of the photosensitive material that remains without being transferred to the optical glass. An antireflection film is formed on the portion corresponding to the flat joint surface. Next, in the three-dimensional initial structure of the photosensitive material, the optical glass material on which the antireflection film is formed is treated with a solvent capable of dissolving the photosensitive material and remains without being transferred to the optical glass. A portion corresponding to the substantially planar bonding surface and a portion corresponding to the bonding surface in the antireflection film are removed. Note that the thin film formation step includes a vacuum deposition method, a CVD method, a sputtering method, and a method of forming a film by spin-coating a solution containing the material of the antireflection film and heating the solution. In this way, it is possible to obtain an antireflection film provided on the optical surface of the optical component without being provided on the joint surface of the optical component.

  Regarding the size of the lens, the lens (array) may be a micro lens (array) (lens diameter = several μm to several hundred μm). Regarding the shape of the lens, the lens may be a spherical lens, an aspherical lens, or an anamorphic lens.

  The diffractive optical element is a Fresnel optical element having a plurality of annular zones, the central annular zone has the maximum pitch and maximum height, and the outer annular zone has the minimum pitch and minimum height. Have. The pitch and height of the annular zone decrease from the center toward the outer periphery. The diffractive optical element is obtained by applying a uniform thickness of electron beam photosensitive material (resist) to optical glass such as low expansion glass such as neo-serum, and pre-baking the uniformly coated electron beam photosensitive material, The electron beam drawing device is used to draw the three-dimensional shape of the diffractive optical element, the electron beam photosensitive material on which the three-dimensional shape of the diffractive optical element is drawn is dry-etched, and the third order of the diffractive optical element on the optical glass It is obtained by transferring the original shape. Note that the optical component as a diffractive optical element having a substantially planar joining surface and the antireflection film provided on the optical surface but not on the joining surface are produced in the same manner as described above.

  Furthermore, the wave front lens is designed by Wavefront Cording System proposed by US CDM Optics, and is obtained by optimizing an optical lens, an image sensor (CCD), and image processing software. It is. Note that the image formed on the image sensor by the wave front lens does not need to be an image that can be recognized by a human. In the Wavefront Cording System, it is only necessary that the final image processed by the image processing software can be recognized by humans. Therefore, this image processing software performs image processing on an image dedicated to the image sensor. By using this Wavefront Cording System, it is possible to achieve both good brightness (F number) and good depth of field limit. In addition, various aberrations can be greatly reduced with a simple lens configuration, and a high-resolution image can be obtained. Note that the optical component as a wavefront lens having a substantially flat cemented surface and the antireflection film provided on the optical surface but not on the cemented surface are produced in the same manner as described above.

  Note that the substrate has a flat surface that is bonded to the bonding surface of the optical component, and may be, for example, a parallel flat plate cover glass having a flat surface that is bonded to the bonding surface of the optical component.

  According to a second aspect of the present invention, in an optical element including an optical component having a substrate and an optical surface, the optical element further includes an antireflection film provided on the optical component, wherein the antireflection film is directly bonded to the substrate. Is an optical element.

  In the optical element according to the second aspect of the present invention, an optical component having an optical surface is provided with an antireflection film, so that reflection of light by the optical surface is reduced and light incident on the optical element is reduced. It can be used more effectively. In particular, the reflection of light onto the substrate by the optical surface can be reduced, and the proportion of light transmitted through the optical component can be improved. Here, the antireflection film includes not only a film that completely prevents reflection of light on the optical surface, but also a film that partially prevents (reduces) reflection of light on the optical surface. Thus, according to the 2nd aspect of this invention, the optical element which can utilize incident light more effectively can be provided.

  Further, in the optical element according to the second aspect of the present invention, since the antireflection film has a joint surface that directly joins to the substrate, the substrate and the antireflection film can be directly connected without using an adhesive such as a resin. Can be joined. In this way, since the substrate and the antireflection film are directly bonded without using a resin adhesive having a relatively large thermal expansion coefficient, the durability or heat resistance of the optical element against temperature changes is improved, and the temperature changes Deformation of the optical element can be suppressed. In addition, since the optical element according to the second aspect of the present invention is used for a long period of time because no resin adhesive is used, the resin does not deteriorate over time. No yellowing). That is, an optical element that is stable over time can be provided. Further, by directly bonding the substrate and the antireflection film without using an adhesive, the optical component provided with the antireflection film can be positioned, bonded, and fixed to the substrate with high accuracy.

  Furthermore, in the second aspect of the present invention, since the substrate and the antireflection film are directly bonded and the substrate and the optical component are not directly bonded, the material of the antireflection film can be directly bonded to the substrate. In this case, the material of the optical component is not limited to a material that can be directly bonded to the substrate, and can be selected from materials suitable for the application.

  In the second aspect of the present invention, preferably, the substrate and the antireflection film are each independently made of a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass. Including and direct bonding is glass direct bonding.

  Here, examples of the silicon oxide include optical glasses such as quartz, Pyrex (registered trademark) glass, Tempax (trade name) glass, and low expansion glass such as Neoceram (trade name). When the substrate and the antireflection film each independently include a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass, that is, the substrate and the antireflection film When both are made of a material containing Si—O bonds, the substrate and the antireflection film can be directly bonded to each other through the bonding surface of the antireflection film. The antireflection film may be a single layer film or a multilayer film including two or more layers. When the antireflection film is a multilayer film of two or more layers, the film closest to the substrate of the antireflection film is made of silicon oxide, silicate, silicate glass, and borosilicate glass. It is preferable that the bonding surface of the film that includes the material selected from the group and is closest to the substrate of the antireflection film is directly bonded to the surface of the substrate corresponding to the bonding surface.

  As a method of direct glass bonding, 1% hydrofluoric acid is applied to the bonding surface of the antireflection film by a tampo method or a spinner method, and the optical component provided with the substrate and the antireflection film is bonded to the bonding surface of the antireflection film. And a method of applying a pressure of about 1.0 MPa to the bonding surface of the antireflection film of the substrate and the optical component and heating at about 60 ° C. for 1 hour.

  Moreover, since the substrate and the antireflection film are directly bonded to the glass without using a resin adhesive having a large thermal expansion coefficient compared to glass, the durability or heat resistance of the optical element against temperature change is improved. The deformation of the optical element due to temperature change can be suppressed. Furthermore, since the optical element according to the second aspect of the present invention is composed of a chemically stable inorganic material as compared with the resin, it is possible to provide an optical element that is stable over time.

  The optical surface may be a convex or concave spherical surface, a convex or concave aspheric surface, or a convex or concave anamorphic surface.

  In the second aspect of the present invention, preferably, the joining surface is substantially flat.

  The bonding surface of the antireflection film and the surface of the substrate corresponding to the bonding surface of the antireflection film have substantially the same shape in order to directly bond each other. Therefore, the bonding surface of the antireflection film and the surface of the substrate corresponding to the bonding surface of the antireflection film may be substantially the same curved surface (spherical surface, aspherical surface, etc.), for example. However, when the bonding surface of the antireflection film and the surface of the substrate corresponding to the bonding surface of the antireflection film are substantially flat, the configuration of the substrate and the like can be simplified. Here, “substantially” means the degree to which direct bonding can be achieved. Further, when the bonding surface is substantially flat, parallel light that enters the optical element and reaches the bonding surface can be emitted as parallel light from the bonding surface. On the other hand, parallel light that enters the optical element and reaches the optical surface can be emitted from the joint surface as convergent light or divergent light.

  In the second aspect of the present invention, preferably, the antireflection film further includes a surface to be bonded to the substrate, which is different from the bonding surface.

  When the antireflection film further includes a surface that is different from the above-described bonding surface and is bonded to the substrate, the bonding strength of the optical component having the substrate and the antireflection film can be further increased. Further, the surface of the antireflection film to be bonded to the substrate, which is different from the bonding surface described above, may be bonded to the corresponding surface of the substrate by using an adhesive, or may be directly bonded like glass direct bonding. . Further, the surface of the antireflection film to be bonded to the substrate, which is different from the bonding surface, may be a curved surface, like the bonding surface, but is preferably substantially flat.

  In the second aspect of the present invention, the space between the substrate and the antireflection film is preferably a vacuum or made of air.

  If the space between the substrate and the antireflective coating provided on the optical surface of the optical component is vacuum or air, that is, filled with a medium having a refractive index of 1, the optical configuration Since the difference between the component material and the refractive index of vacuum or air is large, the design of the optical surface of the optical component can be facilitated. For example, when the optical component is a lens (array), the curvature of the lens surface as the optical surface can be reduced. In addition, when the space between the antireflection film provided on the optical surface of the substrate and the optical component is air, the outside air can pass through the space between the substrate and the antireflection film, so that the optical element Is used together with a device that generates heat, the heat applied to the optical element can be easily released, and the cooling efficiency of the optical element can be increased. On the other hand, when the space between the antireflection film provided on the optical surface of the substrate and the optical component is a vacuum, an optical element having high heat insulation can be provided.

  In order to make the space between the substrate and the antireflection film vacuum (or air), the antireflection film provided on the substrate and the optical component is directly bonded in vacuum (or air).

  In the second aspect of the present invention, preferably, the optical component includes an optical component selected from the group consisting of a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens.

  The lens (array) forms a layer of photosensitive material (photoresist) on a plane-parallel plate of optical glass material, and performs a density distribution mask designed for the desired lens (array) and exposure, development, and curing processes. Using a photolithographic process including, forming a three-dimensional initial structure of the photosensitive material with the desired lens shape, and transferring the three-dimensional initial structure of the photosensitive material to the optical glass material by etching It is produced by doing. The density distribution mask can be obtained by, for example, a method disclosed in JP-A-7-230159.

  Here, an optical component as a lens (array) provided with an antireflection film having a substantially flat joint surface is manufactured as follows. When the form of the three-dimensional initial structure of the photosensitive material is transferred to the optical glass material by etching, the portion corresponding to the substantially planar joining surface in the three-dimensional initial structure of the photosensitive material is the optical glass material. The etching is stopped before being transferred. That is, only the portion corresponding to the optical surface in the three-dimensional initial structure of the photosensitive material is transferred to the optical glass material, and the portion corresponding to the substantially planar joining surface in the three-dimensional initial structure of the photosensitive material is Instead of being transferred to the optical glass material, it remains in the optical glass material, and the plane shape of the plane parallel plate is maintained. Then, the portion of the three-dimensional initial structure of the photosensitive material remaining without being transferred to the optical glass is removed from the optical glass material. Thereby, an optical component as a lens (array) having a substantially flat joint surface is produced. Then, the antireflection film is formed on the entire surface on which the antireflection film is formed in the obtained optical component as a lens (array) having a substantially planar bonding surface by a thin film forming step. Note that the thin film formation step includes a vacuum deposition method, a CVD method, a sputtering method, and a method of forming a film by spin-coating a solution containing the material of the antireflection film and heating the solution. In this manner, an optical component as a lens (array) provided with an antireflection film having a substantially flat joining surface can be obtained.

  Regarding the size of the lens, the lens (array) may be a micro lens (array) (lens diameter = several μm to several hundred μm). Regarding the shape of the lens, the lens may be a spherical lens, an aspherical lens, or an anamorphic lens.

  The diffractive optical element is a Fresnel optical element having a plurality of annular zones, the central annular zone has the maximum pitch and maximum height, and the outer annular zone has the minimum pitch and minimum height. Have. The pitch and height of the annular zone decrease from the center toward the outer periphery. The diffractive optical element is obtained by applying a uniform thickness of electron beam photosensitive material (resist) to optical glass such as low expansion glass such as neo-serum, and pre-baking the uniformly coated electron beam photosensitive material, The electron beam drawing device is used to draw the three-dimensional shape of the diffractive optical element, the electron beam photosensitive material on which the three-dimensional shape of the diffractive optical element is drawn is dry-etched, and the third order of the diffractive optical element on the optical glass It is obtained by transferring the original shape. The optical component as a diffractive optical element having a substantially flat joint surface and the antireflection film provided on the optical component are produced in the same manner as described above.

  Furthermore, the wave front lens is designed by Wavefront Cording System proposed by US CDM Optics, and is obtained by optimizing an optical lens, an image sensor (CCD), and image processing software. It is. Note that the image formed on the image sensor by the wave front lens does not need to be an image that can be recognized by a human. In the Wavefront Cording System, it is only necessary that the final image processed by the image processing software can be recognized by humans. Therefore, this image processing software performs image processing on an image dedicated to the image sensor. By using this Wavefront Cording System, it is possible to achieve both good brightness (F number) and good depth of field limit. In addition, various aberrations can be greatly reduced with a simple lens configuration, and a high-resolution image can be obtained. The optical component as a wavefront lens having a substantially flat joint surface and the antireflection film provided on the optical component are produced in the same manner as described above.

  In addition, the substrate has a flat surface that is bonded to the bonding surface of the antireflection film, and may be, for example, a cover plate of a parallel flat plate having a flat surface that is bonded to the bonding surface of the antireflection film.

  According to a third aspect of the present invention, in the optical element including the optical component having the first refractive surface, the optical component further includes a second refractive surface corresponding to the first refractive surface, The refractive surface has a refractive power with a sign opposite to the sign of the refractive power of the second refractive surface corresponding to the first refractive surface.

  In the third aspect of the present invention, the optical component further includes a second refractive surface corresponding to the first refractive surface, and the first refractive surface corresponds to the second refractive surface. Since the refractive power has a sign opposite to that of the refractive power of the refracting surface, the degree of convergence or divergence of the light converged or diverged by the first refracting surface can be reduced by the second refracting surface. For example, the light incident on the optical element according to the third aspect of the present invention is converged by the refractive power of the first refractive surface of the optical element, and the light emitted from the optical element is not concentrated too much. The degree of convergence of light emitted from the optical element can be reduced by diverging by the refractive power of the second refractive surface of the optical element. Thus, according to the third aspect of the present invention, it is possible to provide an optical element that can more effectively use incident light.

  The optical component according to the third aspect of the present invention is, for example, a meniscus lens (array) in which the center of curvature of the first refractive surface and the center of curvature of the second refractive surface are on the same side.

  In particular, when the optical element according to the third aspect of the present invention is used in combination with a liquid crystal device, the refractive power of the first refracting surface of the optical element is prevented so that light does not strike the liquid crystal driving circuit of the liquid crystal device. To converge the light incident on the optical element, so that the light does not concentrate too much on a specific part of the liquid crystal phase of the liquid crystal device, and so that the emission angle of the light emitted from the liquid crystal device does not become too large. The degree of convergence of light emitted from the optical element can be reduced by the refractive power of the second refractive surface of the optical element. In other words, it is possible to avoid excessive concentration of light on a specific part of the liquid crystal phase of the liquid crystal device, thereby reducing the deterioration of the liquid crystal phase in the liquid crystal device and extending the lifetime of the liquid crystal device compared to conventional liquid crystal devices. Can do. Further, if the optical element is a microlens array, it is possible to avoid an excessively large emission angle of light emitted from the liquid crystal device, so that it transmits the adjacent microlens and the liquid crystal phase. Therefore, it is possible to reduce the mixing of light with each other, and to reduce the color mixture of light having image information emitted from the liquid crystal device, the unevenness of luminance, and the decrease in contrast. Furthermore, it becomes possible to easily design a collimating lens for collimating light emitted from the liquid crystal device.

  In the optical element according to the third aspect of the present invention, a plurality of optical components may be provided as necessary. By providing a plurality of optical components, the design of each optical component can be facilitated, and the performance of the entire optical element can be improved.

  In the third aspect of the present invention, preferably, the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface.

  Here, the refractive power of the first refractive surface is the refractive power of the first refractive surface at the height of the incident light beam, and the refractive power of the second refractive surface is the first refractive power at the height of the emitted light beam. This is the refractive power of the second refractive surface. In other words, in the third aspect of the present invention, the optical element in which the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface is a so-called afocal optical system. is there. Note that “substantially equal” means the degree of convergence or divergence of light incident on the optical element and light emitted from the optical element due to the difference between the refractive power of the first refractive surface and the refractive power of the second refractive surface. Means to some extent within an acceptable range. In addition, the first refractive surface and the second refractive surface are ideally not decentered.

  When the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface, the degree of convergence or divergence of the light incident on the optical element is determined from the optical element. An optical element that is substantially equal to the degree of convergence or divergence of the emitted light can be provided. Here, the degree of convergence or divergence of light incident on the optical element and the degree of convergence or divergence of light emitted from the optical element indicate that the light incident on the optical element and the light emitted from the optical element are parallel lights. Contains zero meaning. That is, if the light incident on the optical element is convergent light, the light that converges to the same extent as the light incident on the optical element is emitted from the optical element, and the light incident on the optical element is divergent light. If there is, light that diverges to the same extent as the light incident on the optical element is emitted from the optical element, and if the light incident on the optical element is substantially parallel light, light that is substantially parallel light is emitted. The light is emitted from the optical element.

  For example, if the optical element is a spherical or aspherical lens (array), the radius of curvature r1 of the first surface of the lens, the radius of curvature r2 of the second surface, the thickness d of the center of the lens, and the lens The lens may be designed so that the refractive index n of the material satisfies the relational expression n (r1-r2) = (n-1) d. In addition, about the code | symbol of r1 and r2, a lens is a meniscus lens normally and it is r1 * r2> 0. If the first refractive surface is a convex surface, r1> r2> 0 (concave meniscus lens), and the absolute value of the radius of curvature of the first refractive surface is the absolute value of the radius of curvature of the second refractive surface. Greater than the value. In this case, the parallel light incident on the first refracting surface is converged on the first refracting surface, the diameter of the light beam is reduced, and the parallel light is emitted from the second refracting surface. If the first refractive surface is concave, r2 <r1 <0 (concave meniscus lens), and the absolute value of the radius of curvature of the first refractive surface is the absolute value of the radius of curvature of the second refractive surface. Smaller than the value (| r1 | <| r2 |). In this case, the parallel light incident on the first refracting surface is diverged by the first refracting surface, the diameter of the light beam is enlarged, and the parallel light is emitted from the second refracting surface.

  In particular, in the third aspect of the present invention, an optical element in which the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface is used in combination with a liquid crystal device. In the case where substantially parallel light emitted from the light source is incident on the optical element, the light is incident on the optical element by the refractive power of the first refractive surface of the optical element so that the light does not hit the liquid crystal driving circuit of the liquid crystal device. The second refraction of the optical element so that the substantially parallel light is converged, the light is not concentrated on a specific part of the liquid crystal phase of the liquid crystal device, and the emission angle of the light emitted from the liquid crystal device is reduced. Due to the refractive power of the surface, substantially parallel light can be emitted from the optical element toward the liquid crystal phase of the liquid crystal device. That is, since light does not concentrate on a specific part of the liquid crystal phase of the liquid crystal device, the deterioration of the liquid crystal phase in the liquid crystal device can be greatly reduced, and the lifetime of the liquid crystal device can be significantly increased as compared with the conventional liquid crystal device. Also, if the optical element is a microlens array, the light emitted from the liquid crystal device is substantially parallel light, and the light emission angle is small, so that it passes through the adjacent microlens and passes through the liquid crystal phase. Thus, the mixing of light with each other can be greatly reduced, and the color mixing of light with image information emitted from the liquid crystal device, the unevenness of luminance, and the decrease in contrast can be greatly reduced. Furthermore, the design of the collimating lens for further collimating the substantially parallel light emitted from the liquid crystal device can be greatly facilitated.

  Here, the substantially parallel light emitted from the liquid crystal device is preferably a light beam having an emission angle within 0.1 ° with respect to ideal parallel light. When the substantially parallel light is a light beam having an emission angle within 0.1 ° with respect to the ideal parallel light, it can be regarded as substantially parallel light with respect to the collimating lens. On the other hand, in order to sufficiently correct the light emitted from the liquid crystal device with the collimator lens, the light emitted from the liquid crystal device is a light beam having an emission angle within ± 4 ° with respect to ideal parallel light. It is preferable to become.

  The first refracting surface and the second refracting surface may be a convex or concave spherical surface, a convex or concave aspheric surface, or a convex or concave anamorphic surface, respectively.

  In the third aspect of the present invention, it preferably further includes a substrate, and the optical component has a bonding surface that directly bonds to the substrate.

  In this case, since the optical component has a bonding surface directly bonded to the substrate, the substrate and the optical component can be directly bonded without using an adhesive such as a resin. In this way, since the substrate and the optical component are directly bonded without using a resin adhesive having a relatively large thermal expansion coefficient, the durability or heat resistance of the optical element against temperature change is improved, and the temperature change Deformation of the optical element can be suppressed. In addition, since the resin adhesive is not used, the optical element according to the third aspect of the present invention does not deteriorate over time even when used for a long period of time. No yellowing). That is, an optical element that is stable over time can be provided. Furthermore, by directly bonding the substrate and the optical component without using an adhesive, the optical component can be positioned, bonded, and fixed to the substrate with high accuracy.

  Further, the bonding surface of the optical component that is directly bonded to the substrate may be a surface that has been subjected to a process of absorbing or scattering light. For example, if the optical component is a component including a lens array, a joint surface that absorbs light is provided at a portion between the lens arrays in the optical component, and mixing of light passing between adjacent lens arrays is performed. Can be reduced.

  In the third aspect of the present invention, preferably, the substrate and the optical component are each independently a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass. Including and direct bonding is glass direct bonding.

  Here, examples of the silicon oxide include optical glasses such as quartz, Pyrex (registered trademark) glass, Tempax (trade name) glass, and low expansion glass such as Neoceram (trade name). If the substrate and the optical component each independently comprise a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass, ie, the substrate and optical component When both are made of a material containing Si—O bonds, the substrate and the optical component can be directly bonded to each other through the bonding surface of the optical component.

  As a method of direct glass bonding, 1% hydrofluoric acid is applied to the bonding surface of the optical component by the tampo method, the substrate and the optical component are brought into contact with each other through the bonding surface, and the bonding surface of the substrate and the optical component And a method of heating at about 60 ° C. for 1 hour while applying a pressure of about 1.0 MPa.

  In addition, since the substrate and the optical components are directly bonded to the glass without using a resin adhesive having a large thermal expansion coefficient compared to glass, the durability or heat resistance of the optical element against temperature changes is improved. The deformation of the optical element due to temperature change can be suppressed. Furthermore, since the optical element which is the third aspect of the present invention is composed of a chemically stable inorganic material as compared with the resin, an optical element that is stable over time can be provided.

  The substrate and the optical component may be bonded with an adhesive such as a resin depending on the usage environment of the optical element.

  In the third aspect of the invention, preferably the space between the substrate and the optical component is a vacuum or consists of air.

  If the space between the substrate and the optical component is vacuum or air, i.e. filled with a medium having a refractive index of 1, the optical component material and the refractive index of the vacuum or air Therefore, the design of the first refractive surface and the second refractive surface of the optical component can be facilitated. For example, when the optical component is a lens (array), the curvatures of the lens surfaces as the first refracting surface and the second refracting surface can be reduced. Also, if the space between the substrate and the optical component is air, the outside air can be passed through the space between the substrate and the optical component, so that the optical element is used with a device that generates heat. In this case, the heat given to the optical element can be easily released, and the cooling efficiency of the optical element can be increased. On the other hand, when the space between the substrate and the optical component is a vacuum, an optical element having high heat insulation can be provided.

  In addition, in order to make the space between the substrate and the optical component a vacuum (or air), the substrate and the optical component are directly bonded in a vacuum (or air).

  In the third aspect of the present invention, preferably, the optical component is bonded to the substrate via an adhesive. That is, the space between the substrate and the optical component may be filled with an adhesive such as a resin according to the use environment of the optical element. Thus, when the optical component is bonded to the substrate via the adhesive, the optical component can be easily bonded to the substrate.

  In the third aspect of the present invention, preferably, the optical component further includes a fourth surface corresponding to a third surface and a third surface different from the first refractive surface and the second refractive surface, The third surface and the fourth surface are substantially flat.

  In the third aspect of the present invention, when the optical component further includes a third surface and a fourth surface, which are substantially planar, different from the first refractive surface and the second refractive surface, Light passing through the third surface and the fourth surface is not converged or diverged, and the degree of convergence or divergence of the light passing through the third surface and the fourth surface is maintained. For example, the third surface may be provided at the center of the first refracting surface, and the fourth surface may be provided at the center of the second refracting surface. When the parallelism of the light passing through the central portion of the first refractive surface and the second refractive surface is high, the light does not converge or diverge at the central portion of the first refractive surface and the second refractive surface. The third surface provided at the center of the first refracting surface and the fourth surface provided at the center of the second refracting surface may be passed. Note that “substantially” means that parallel light can be transmitted so that the degree of convergence or divergence of light passing through the third surface and the fourth surface is within an allowable range.

  In the third aspect of the present invention, preferably, the optical component includes a component selected from the group consisting of a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens.

  A lens (array) as an optical component forms a layer of a photosensitive material (photoresist) on a plane-parallel plate of optical glass material, a density distribution mask designed for the desired lens (array), and exposure and development. And a photolithographic process including a curing process to form a three-dimensional initial structure of the photosensitive material with a desired lens shape, and to form the three-dimensional initial structure of the photosensitive material by etching. It is produced by transferring to an optical glass material. The density distribution mask can be obtained by, for example, a method disclosed in JP-A-7-230159. Therefore, when the first refracting surface and / or the second refracting surface is a surface of a lens (array), a layer of a photosensitive material (photoresist) is formed on one side of a plane parallel plate of optical glass material. A three-dimensional initial structure of a photosensitive material with a first refractive surface configuration using a density distribution mask designed with respect to the first refractive surface and a photolithographic process including exposure, development, and curing processes. Forming a body and transferring the form of the three-dimensional initial structure of the photosensitive material to one side of a plane parallel plate of optical glass material by etching. Next, a layer of photosensitive material (photoresist) is formed on the other side of the plane-parallel plate of optical glass material, including a density distribution mask designed for the second refractive surface and exposure, development, and curing processes. A photolithographic process is used to form a photosensitive material three-dimensional initial structure with a second refractive surface configuration, and the photosensitive material three-dimensional initial structure configuration is etched to form an optical glass material. Transfer to the other surface of the plane parallel plate.

  In addition, when the third surface (fourth surface), which is practically a flat surface, is formed on the first refracting surface (second refracting surface), the third surface in the three-dimensional initial structure of the photosensitive material is used. A portion corresponding to the third surface (fourth surface) in the three-dimensional initial structure of the photosensitive material when the form of one refractive surface (second refractive surface) is transferred to the optical glass material by etching. However, etching is stopped before it is transferred to the optical glass material. That is, only the portion corresponding to the first refractive surface (second refractive surface) in the three-dimensional initial structure of the photosensitive material is transferred to the optical glass material, and the third in the three-dimensional initial structure of the photosensitive material. The portion corresponding to this surface (fourth surface) is not transferred to the optical glass material, but remains in the optical glass material, and the plane shape of the parallel plane plate is maintained. Then, the portion corresponding to the third surface (fourth surface) in the three-dimensional initial structure of the photosensitive material remaining without being transferred to the optical glass is removed from the optical glass material. In this way, an optical component as a lens (array) having a first refracting surface (second refracting surface) having a third surface (fourth surface) that is practically flat is obtained. Can do.

  Regarding the size of the lens, the lens (array) may be a micro lens (array) (lens diameter = several μm to several hundred μm). Regarding the shape of the lens, the lens may be a spherical lens, an aspherical lens, or an anamorphic lens.

  The diffractive optical element as an optical component is a Fresnel optical element having a plurality of annular zones on the first refractive surface and / or the second refractive surface, and the central annular zone has a maximum pitch and a maximum height. The outer ring has a minimum pitch and a minimum height. The pitch and height of the annular zone decrease from the center toward the outer periphery. The diffractive optical element is a uniform electron beam photosensitive material (resist) coated on one or both sides of an optical glass such as neo-serum or other low-expansion glass. The three-dimensional shape of the diffractive optical element is drawn according to the first refractive surface and / or the second refractive surface using the electron beam drawing device, and the three-dimensional shape of the diffractive optical element is drawn. It can be obtained by dry etching the photosensitive material for electron beam and transferring the three-dimensional shape of the diffractive optical element to the optical glass. An optical component as a diffractive optical element having a substantially flat third surface (fourth surface) is manufactured in the same manner as described above.

  Furthermore, the wave front lens is designed by Wavefront Cording System proposed by US CDM Optics, and is obtained by optimizing an optical lens, an image sensor (CCD), and image processing software. It is. Note that the image formed on the image sensor by the wave front lens does not need to be an image that can be recognized by a human. In the Wavefront Cording System, it is only necessary that the final image processed by the image processing software can be recognized by humans. Therefore, this image processing software performs image processing on an image dedicated to the image sensor. By using this Wavefront Cording System, it is possible to achieve both good brightness (F number) and good depth of field limit. In addition, various aberrations can be greatly reduced with a simple lens configuration, and a high-resolution image can be obtained. The optical component as a wave front lens having a substantially flat surface is manufactured in the same manner as described above.

  Note that the substrate has a flat surface that is bonded to the bonding surface of the optical component, and may be, for example, a cover plate of a parallel flat plate having a flat surface that is bonded to the bonding surface of the optical component.

  In order to increase the bonding strength between the optical component and the substrate, a surface to be bonded to the substrate may be further provided on the outer periphery of the optical component. Further, the optical component is provided with an antireflection film as necessary (for example, on the first refracting surface, the second refracting surface, the third surface, the fourth surface, etc.). The reflection of light inside may be reduced.

  In addition, when a convex portion is provided on the outer periphery of the optical component of the optical element of the first or second aspect of the present invention or the optical component of the optical element of the third aspect, and a concave portion is formed at the center of the convex portion, The recess serves as a mark indicating the outer periphery of the optical component or the optical component. Further, a convex portion is provided on one of the outer periphery of the optical component or the optical component and the substrate, and a concave portion that fits the convex portion is provided on the other of them, and the outer periphery of the optical component or the optical component and the relative position of the substrate are provided. Positioning is easy.

  A fourth aspect of the present invention is a liquid crystal device including the optical element of the first, second, or third aspect of the present invention and a liquid crystal. A liquid crystal device according to a fourth aspect of the present invention includes a liquid crystal phase including a liquid crystal composed of liquid crystal molecules, a liquid crystal substrate supporting the liquid crystal phase, and a liquid crystal driving circuit for controlling the alignment of the liquid crystal molecules by applying a voltage to the liquid crystal. A collimator lens (for example, including a thin film transistor and a wiring) for correcting the parallelism of light emitted from the optical element may be included.

  A fifth aspect of the present invention is a liquid crystal projector including the liquid crystal device according to the fourth aspect of the present invention. The liquid crystal projector according to the fifth aspect of the present invention is obtained by replacing the liquid crystal device in a conventional arbitrary liquid crystal projector with the liquid crystal device according to the fourth aspect of the present invention.

  The optical element according to the first, second, or third aspect of the present invention is not limited to use in a liquid crystal device, and can also be used in a writing optical system of a digital camera or a copying machine.

  FIG. 1 is a diagram illustrating an example of a liquid crystal device including an optical element according to the first aspect of the present invention. As shown in FIG. 1, the liquid crystal device including the optical element according to the first aspect of the present invention includes a microlens array 12 as an optical component, an antireflection film 14 provided on the optical surface of the microlens array 12, And an optical element composed of a cover glass 16 as a substrate of the optical element, further including a liquid crystal substrate 22 and a liquid crystal phase 24 provided on the liquid crystal substrate 22, wherein the liquid crystal phase 24 includes a plurality of liquid crystal molecules 26, A liquid crystal driving circuit 28 including a transistor and wiring is provided. Although not shown, another substrate different from the cover glass 16 may be provided between the microlens array 12 and the liquid crystal phase 24.

  The microlens array 12 has a substantially flat joining surface that joins the cover glass 16, and has a spherical optical surface around the joining surface. The antireflection film 14 is provided on the optical surface and not on the bonding surface. Since the antireflection film is provided on the optical surface of the microlens array 12, reflection of light by the optical surface can be reduced and light incident on the optical element can be used more effectively. Here, the microlens array 12 and the cover glass 16 are made of, for example, low expansion glass such as quartz or neoceram, and correspond to the bonding surface of the microlens array 12 and the bonding surface of the cover glass 16. The surfaces are bonded to each other by direct glass bonding. Since the microlens array 12 and the cover glass 16 are directly bonded to the glass without using a resin adhesive having a larger thermal expansion coefficient than that of the glass, durability or heat resistance of the optical element with respect to temperature changes. And an optical element that is stable over time can be provided. Further, the microlens array 12 has a convex portion 18 having a surface that is different from the above-described bonding surface and bonded to the cover glass 16. The bonding strength between the microlens array 12 and the cover glass 16 can be increased by directly bonding the convex portion 18 of the microlens array 12 to the cover glass 16. The space between the antireflection film 14 and the cover glass 16 is vacuum or air. Since the space between the antireflection film 14 and the cover glass 16 is vacuum or air, the radius of curvature of the optical surface of the microlens in the microlens array 12 can be made relatively large, and the design of the microlens array 12 is facilitated. be able to.

  The substantially parallel light emitted from a light source such as a lamp enters the microlens array 12 through the cover glass 16. The light that enters the microlens array 12 and passes through the joint surface provided at the central portion of the microlens of the microlens array 12 enters the liquid crystal phase 24 as substantially parallel light. On the other hand, light that enters the microlens array 12 and passes through a spherical optical surface provided in the peripheral portion of the microlens of the microlens array 12 is refracted by the optical surface and enters the liquid crystal phase 24 as convergent light. . Here, with respect to the light incident on the optical surface of the microlens array 12, reflection by the optical surface is reduced by the antireflection film provided on the optical surface, and the light incident on the optical surface can be made with higher efficiency. The liquid crystal phase 24 can be emitted. Therefore, the light incident on the optical element can be used more effectively.

  The light incident on the liquid crystal phase 24 irradiates the liquid crystal molecules 26, and the alignment of the liquid crystal molecules 26 is controlled by the liquid crystal driving circuit 28. Then, by controlling the voltage applied to the liquid crystal driving circuit in accordance with the desired image information, the liquid crystal molecules 26 can be properly aligned, and the desired image information can be imparted to the light passing through the liquid crystal phase 24. The light to which the image information emitted from the liquid crystal substrate 22 side through the liquid crystal phase 24 is added is collimated by a collimator lens (not shown) and enters a projection lens (not shown) as parallel light. And the light to which image information was given is projected on a screen by a projection lens.

  2A to 2F are views for explaining a method for producing an optical element according to the first embodiment of the present invention. Specifically, a method for manufacturing the optical element shown in FIG. 1 will be described.

  First, as shown in FIG. 2 (a), a photosensitive material (photoresist) 34 for semiconductor is applied to an optical glass material 32 of low expansion glass such as quartz or neoceram having a plane-parallel plate configuration, and optical A layer of photosensitive material 34 is formed on a plane parallel plate of glass material 32. Next, a density distribution mask 36 designed in advance corresponding to the shape of the microlens array 12 shown in FIG. 1 is positioned with respect to the layer of the photosensitive material 34. The density distribution mask has an exposure area divided into unit cells having an appropriate shape and size corresponding to the shape of the microlens array 12 without a gap. Further, for the light shielding pattern in the unit cell of the density distribution mask, the transmitted light amount or the light shielding amount of the unit cell is set to a value that can realize a desired pattern of the photosensitive material. Next, light with which the photosensitive material 34 reacts is irradiated onto the layer of the photosensitive material 34 on the plane parallel plate of the optical glass material 32 through the density distribution mask 36, and the photosensitive material is subjected to a normal photolithography process. 34 layers are developed and cured.

  As a result, as shown in FIG. 2B, a layer of the photosensitive material 34 having a shape corresponding to the shape of the microlens array 12 is formed on the plane parallel plate of the optical glass material 32. Here, the shape of the microlens array 12 is a shape having a flat joint surface and a spherical optical surface on the outer periphery of the joint surface.

  Next, as shown in FIG. 2C, the plane parallel plate of the optical glass material 32 is etched according to the shape corresponding to the shape of the microlens array 12 in the layer of the photosensitive material 34. Here, the etching is performed on the parallel flat plate of the optical glass material 32 provided with the layer of the photosensitive material 34, using a semiconductor dry etching apparatus, and on the surface of the parallel flat plate of the optical glass material 32. Both the layer of photosensitive material 34 and the plane parallel plate of optical glass material 32 are etched by impinging the etching species in the vertical direction. Thus, from the plane-parallel plate portion of the optical glass material 32 corresponding to the thin portion of the photosensitive material 34 layer to the plane-parallel plate portion of the optical glass material 32 corresponding to the thick portion of the photosensitive material 34 layer. Etching is performed sequentially. Here, as shown in FIG. 2C, the portion of the plane parallel plate of the optical glass material 32 corresponding to the optical surface of the microlens array 12 is etched, and the optical glass material corresponding to the bonding surface of the microlens array 12 is etched. The etching is finished in a state where the portions of the 32 plane parallel plates are not etched. Then, the portion of the plane parallel plate of the optical glass material 32 corresponding to the optical surface of the microlens array 12 has a spherical shape by etching, and the plane of the plane parallel plate of the optical glass material 32 corresponding to the bonding surface of the microlens array 12 is obtained. The portion is not etched and remains in a planar shape that is the shape of the surface of the plane parallel plate. In this way, a microlens array of the optical glass material 32 as an optical component having a shape having a planar optical surface and a spherical optical surface on the outer periphery of the optical interface is formed. In (dry) etching, if the etching selectivity is changed, the etching can be achieved with a shape (different height, spherical surface, aspherical surface, etc.) different from the shape of the photosensitive material. Further, when the time point at which dry etching is finished is changed, that is, when the etching time is changed, the height of the photosensitive material to be etched changes, and at the same time, the shape or area of the unetched plane portion of the parallel plane plate of the optical glass material 32 Changes. For example, when the shape of the planar portion that is not etched is a circle, the diameter of the circle changes. In addition, when the shape of the planar portion that is not etched is a rectangle, the length of the four sides of the rectangle changes.

As a specific method of etching, the plane parallel plate of the optical glass material 32 provided with the layer of the photosensitive material 34 is cooled to 5 ° C., and etching is performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. . Here, for example, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 10 sccm, the flow rate of Ar gas is 5 sccm, the pressure of the mixed gas is 25 mTorr, and the bias is 450 W, the upper power is 2.0 kW, the etching rate is 5 μm / min, and the processing time is 4.5 seconds. When C ₄ F ₈ gas is used, the flow rate of C ₄ F ₈ gas is 100 sccm, the pressure of the gas is 20 mTorr, the bias is 5 W, and the upper power is 1.8 kW. Yes, the processing time is 3-4 minutes.

  Next, as shown in FIG. 2D, the layer of the photosensitive material 34 remains on the bonding surface of the microlens array 12 of the optical glass material 32 having a spherical optical surface and a flat bonding surface. Then, an antireflection film 38 is formed on the optical surface of the microlens array 12 of the optical glass material 32 and the layer of the photosensitive material 34 remaining on the bonding surface of the microlens array 12 in a thin film forming step. Here, in the thin film formation step, a solution containing a material for the vacuum deposition method, the CVD method, the sputtering method, and the antireflection film 38 is applied by spin coating, and the applied solution is heated to form the antireflection film 38. Either method may be used. Here, an antireflection film 38 that prevents reflection of light having a wavelength of visible light is formed.

  Next, as shown in FIG. 4E, the layer of the photosensitive material 34 remaining on the bonding surface remains by the lift-off method, and the antireflection film 38 is formed on the optical surface and the layer of the photosensitive material 34. The microlens array 12 of the optical glass material 32 is treated with a solvent capable of dissolving the photosensitive material 34 (heating, ultrasonic vibration, etc., if necessary), and The layer of the photosensitive material 34 remaining on the bonding surface of the microlens array 12 is removed. Thereby, the layer of the photosensitive material 34 remaining on the bonding surface of the microlens array 12 of the optical glass material 32 and the antireflection film 38 provided on the layer of the photosensitive material 34 are removed. Therefore, an antireflection film 38 is provided on the optical surface of the microlens array 12, and an optical element in which the bonding surface of the microlens array 12 is a flat surface of the optical glass material 32 can be obtained.

  Finally, as shown in FIG. 8F, the bonding surface of the microlens array 12 of the optical glass 23 and the cover glass 16 of the same optical glass 32 are bonded by direct glass bonding. First, 1% hydrofluoric acid is thinly applied to the joint surface of the optical glass 23 of the microlens array 12 by a tampo method, and the cover glass 16 of the optical glass 32 is brought into contact with the air. Next, a pressure of about 1.0 MPa is applied to the bonding surface of the microlens array 12 of the optical glass 23 and the corresponding surface of the cover glass 16 of the optical glass 32 which are brought into contact with each other, and heated at 60 ° C. for 1 hour. Thereafter, the microlens array 12 and the cover glass 16 are washed with an organic solvent and dried in a vacuum. In this way, as shown in FIG. 1, the cover lens 16 and the microlens array 12 having a flat bonding surface directly bonded to the cover glass 16 and the spherical optical surface provided with the antireflection film 38 are included. An optical element can be obtained.

  In addition, you may provide the convex part 18 which is a partition outside the area | region of the micro lens array 12 in an optical element, and it is preferable that the convex part 18 has a plane joined to a cover glass.

  FIG. 3 is a diagram illustrating an example of a liquid crystal device including an optical element according to the second aspect of the present invention. As shown in FIG. 3, a liquid crystal device including an optical element according to the second aspect of the present invention includes a microlens array 12 as an optical component, an antireflection film 14 provided on the microlens array 12, and an optical element. Including a liquid crystal substrate 22 and a liquid crystal phase 24 provided on the liquid crystal substrate 22. The liquid crystal phase 24 includes a plurality of liquid crystal molecules 26, and includes a thin film, a transistor, and a wiring. A liquid crystal driving circuit 28 is provided. Although not shown, another substrate different from the cover glass 16 may be provided between the microlens array 12 and the liquid crystal phase 24.

  The microlens array 12 has a flat portion corresponding to the bonding surface of the antireflection film 14 that is substantially flat and bonded to the cover glass 16, and has a spherical optical surface around the flat portion. The antireflection film 14 is provided on the cover glass side surface of the microlens array 12. Since the antireflection film 14 is provided on the microlens array 12, reflection of light by the surface of the microlens array 12 on which the antireflection film 14 is provided is reduced, and light incident on the optical element is used more effectively. be able to. Here, the antireflection film 14 and the cover glass 16 are each made of, for example, low expansion glass such as quartz or neoceram, and correspond to the bonding surface of the antireflection film 14 and the bonding surface of the cover glass 16. The surfaces are bonded to each other by direct glass bonding. Since the antireflection film 14 and the cover glass 16 are directly bonded to the glass without using a resin adhesive having a larger thermal expansion coefficient than that of the glass, the durability or heat resistance of the optical element against temperature change And an optical element that is stable over time can be provided. Further, the microlens array 12 has a convex portion 18 provided with an antireflection film 14 having a surface that is different from the above-described bonding surface and bonded to the cover glass 16. By bonding the antireflection film 14 provided on the convex portion 18 of the microlens array 12 directly to the cover glass 16, the bonding strength between the antireflection film 14 and the cover glass 16 can be increased. The space between the antireflection film 14 and the cover glass 16 is vacuum or air. Since the space between the antireflection film 14 and the cover glass 16 is vacuum or air, the radius of curvature of the optical surface of the microlens in the microlens array 12 can be made relatively large, and the design of the microlens array 12 is facilitated. be able to.

  The substantially parallel light emitted from a light source such as a lamp enters the microlens array 12 through the cover glass 16. The light that enters the microlens array 12 and passes through the joint surface provided at the central portion of the microlens of the microlens array 12 enters the liquid crystal phase 24 as substantially parallel light. On the other hand, light that enters the microlens array 12 and passes through a spherical optical surface provided in the peripheral portion of the microlens of the microlens array 12 is refracted by the optical surface and enters the liquid crystal phase 24 as convergent light. . Here, the light incident on the microlens array 12 is reduced in reflection by the surface of the microlens array 12 by the antireflection film provided on the microlens array 12, and is incident on the surface of the microlens array 12. The liquid crystal phase 24 can be emitted with higher efficiency. Therefore, the light incident on the optical element can be used more effectively.

  The light incident on the liquid crystal phase 24 irradiates the liquid crystal molecules 26, and the alignment of the liquid crystal molecules 26 is controlled by the liquid crystal driving circuit 28. Then, by controlling the voltage applied to the liquid crystal driving circuit in accordance with the desired image information, the liquid crystal molecules 26 can be properly aligned, and the desired image information can be imparted to the light passing through the liquid crystal phase 24. The light to which the image information emitted from the liquid crystal substrate 22 side through the liquid crystal phase 24 is added is collimated by a collimator lens (not shown) and enters a projection lens (not shown) as parallel light. And the light to which image information was given is projected on a screen by a projection lens.

  4A to 4F are views for explaining a method for producing an optical element according to the second embodiment of the present invention. Specifically, a method for manufacturing the optical element shown in FIG. 3 will be described.

  First, as shown in FIG. 4 (a), a photosensitive material (photoresist) 34 for semiconductor is applied to an optical glass material 32 of low expansion glass such as quartz or neoceram having a parallel flat plate shape, and optical A layer of photosensitive material 34 is formed on a plane parallel plate of glass material 32. Next, a density distribution mask 36 designed in advance corresponding to the shape of the microlens array 12 shown in FIG. 3 is positioned with respect to the layer of the photosensitive material 34. The density distribution mask has an exposure area divided into unit cells having an appropriate shape and size corresponding to the shape of the microlens array 12 without a gap. Further, for the light shielding pattern in the unit cell of the density distribution mask, the transmitted light amount or the light shielding amount of the unit cell is set to a value that can realize a desired pattern of the photosensitive material. Next, light with which the photosensitive material 34 reacts is irradiated onto the layer of the photosensitive material 34 on the plane parallel plate of the optical glass material 32 through the density distribution mask 36, and the photosensitive material is subjected to a normal photolithography process. 34 layers are developed and cured.

  As a result, as shown in FIG. 4B, a layer of the photosensitive material 34 having a shape corresponding to the shape of the microlens array 12 is formed on the plane parallel plate of the optical glass material 32. Here, the shape of the microlens array 12 is a shape having a flat joint surface and a spherical optical surface on the outer periphery of the joint surface.

  Next, as shown in FIG. 4C, the plane parallel plate of the optical glass material 32 is etched according to the shape corresponding to the shape of the microlens array 12 in the layer of the photosensitive material 34. Here, the etching is performed on the parallel flat plate of the optical glass material 32 provided with the layer of the photosensitive material 34, using a semiconductor dry etching apparatus, and on the surface of the parallel flat plate of the optical glass material 32. Both the layer of photosensitive material 34 and the plane parallel plate of optical glass material 32 are etched by impinging the etching species in the vertical direction. Thus, from the plane-parallel plate portion of the optical glass material 32 corresponding to the thin portion of the photosensitive material 34 layer to the plane-parallel plate portion of the optical glass material 32 corresponding to the thick portion of the photosensitive material 34 layer. Etching is performed sequentially. Here, as shown in FIG. 4 (c), the portion of the plane parallel plate of the optical glass material 32 corresponding to the optical surface of the microlens array 12 is etched, and the antireflection film 38 provided on the microlens array 12 is bonded. Etching is completed in a state where the plane-parallel plate portion of the optical glass material 32 corresponding to the surface is not etched. Then, the portion of the plane parallel plate of the optical glass material 32 corresponding to the optical surface of the microlens array 12 has a spherical shape by etching, and the optical glass corresponding to the bonding surface of the antireflection film 38 provided on the microlens array 12. The portion of the plane parallel plate of the material 32 is not etched and remains in the plane shape which is the shape of the surface of the plane parallel plate. In this way, a microlens array of the optical glass material 32 is formed as an optical component having a shape corresponding to the flat joint surface of the antireflection film 38 and a spherical optical surface on the outer periphery of the flat surface. . In (dry) etching, if the etching selectivity is changed, the etching can be achieved with a shape (different height, spherical surface, aspherical surface, etc.) different from the shape of the photosensitive material. Further, when the time point at which dry etching is finished is changed, that is, when the etching time is changed, the height of the photosensitive material to be etched changes, and at the same time, the shape or area of the unetched plane portion of the parallel plane plate of the optical glass material 32 Changes. For example, when the shape of the planar portion that is not etched is a circle, the diameter of the circle changes. In addition, when the shape of the planar portion that is not etched is a rectangle, the length of the four sides of the rectangle changes.

As a specific method of etching, the plane parallel plate of the optical glass material 32 provided with the layer of the photosensitive material 34 is cooled to 5 ° C., and etching is performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. . Here, for example, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 10 sccm, the flow rate of Ar gas is 5 sccm, the pressure of the mixed gas is 25 mTorr, and the bias is 450 W, the upper power is 2.0 kW, the etching rate is 5 μm / min, and the processing time is 4.5 seconds. When C ₄ F ₈ gas is used, the flow rate of C ₄ F ₈ gas is 100 sccm, the pressure of the gas is 20 mTorr, the bias is 5 W, and the upper power is 1.8 kW. Yes, the processing time is 3-4 minutes.

  Next, as shown in FIG. 4D, the layer of the photosensitive material 34 remaining on the microlens array 12 of the optical glass material 32 is removed by a removal process such as a cleaning process or dry ashing. As a result, it is possible to obtain the microlens array 12 of the optical glass material 32 having a plane portion corresponding to the bonding surface of the antireflection film 38 and a spherical optical surface formed on the outer periphery of the plane portion.

Next, as shown in FIG. 4E, a microlens of an optical glass material 32 having a flat surface corresponding to the bonding surface of the antireflection film 38 and a spherical optical surface formed on the outer periphery of the flat surface. An antireflection film 38 is formed on the array 12 in the thin film forming step. Here, in the thin film formation step, a solution containing a material for the vacuum deposition method, the CVD method, the sputtering method, and the antireflection film 38 is applied by spin coating, and the applied solution is heated to form the antireflection film 38. Either method may be used. Here, an antireflection film 38 that prevents reflection of light having a wavelength of visible light is formed. Note that the film in contact with the cover glass 16 in the antireflection film 38 includes silicon dioxide SiO ₂ similar to the optical glass material 32 in order to directly bond the antireflection film 38 and the overbar glass 16 to the glass. Therefore, an optical element in which the antireflection film 38 is provided on the microlens array 12 and the joint surface of the antireflection film is a plane of the optical glass material 32 can be obtained.

  Finally, as shown in FIG. 8F, the bonding surface of the antireflection film 38 of the optical glass 23 provided on the microlens array 12 and the cover glass 16 of the same optical glass 32 are bonded by direct glass bonding. First, 1% hydrofluoric acid is thinly applied to the bonding surface of the antireflection film 38 provided on the microlens array 12 by a tampo method or a spinner method, and the cover glass 16 of the optical glass 32 is brought into contact with the air. Next, a pressure of about 1.0 MPa is applied to the bonding surface of the antireflection film 38 of the optical glass 23 and the corresponding surface of the cover glass 16 of the optical glass 32 provided on the microlens array 12 in contact with each other, Heat at 60 ° C. for 1 hour. Thereafter, the microlens array 12 and the cover glass 16 are washed with an organic solvent and dried in a vacuum. In this way, the cover glass 16, the microlens array 12 having a spherical optical surface, and the antireflection film 38 provided on the microlens array 12, as shown in FIG. An optical element having a flat joining surface that directly joins the glass 16 and the glass can be obtained.

  In addition, the convex part 18 which is a partition may be provided outside the area | region of the microlens array 12 in an optical element, and the antireflection film 38 provided in the convex part 18 has a plane joined to the cover glass 16. preferable.

  FIG. 5 is a view for explaining one example of a liquid crystal device including an optical element according to the third embodiment of the present invention. As shown in FIG. 5, the liquid crystal device including the optical element according to the third aspect of the present invention is an optical element (microlens array) including an optical element substrate 42 and a plurality of microlenses 44 as a plurality of optical components. The liquid crystal phase 24 further includes a liquid crystal substrate 22 and a liquid crystal phase 24 provided on the liquid crystal substrate 22, and the liquid crystal phase 24 includes a plurality of liquid crystal molecules 26, and a liquid crystal driving circuit 28 including a thin film, a transistor, and wiring is provided. Yes. Although not shown, a cover glass that protects the plurality of microlenses 44 may be provided.

  In an optical element (microlens array) including a microlens 44 as a plurality of optical components having a plurality of first refracting surfaces, the microlens 44 further includes a second refracting surface corresponding to the first refracting surface. The first refractive surface includes a refractive power having a sign opposite to that of the second refractive surface corresponding to the first refractive surface. Further, the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface. More specifically, the microlens 44 is a concave meniscus lens having a convex surface facing the light source and a concave surface facing the liquid crystal phase. That is, the first refractive surface of the microlens 44 is a convex surface, the second refractive surface is a concave surface, and the refractive power of the convex surface and the absolute value of the refractive power of the concave surface are substantially the same. The signs of the refractive power and the concave power are opposite. That is, the microlens 44 is an afocal optical system. Note that the radius of curvature of the convex surface of the microlens 44 is larger than the radius of curvature of the concave surface of the microlens 44. The absolute values of the refractive power of the convex surface and the concave surface of the microlens 44 are substantially the same, and the signs of the refractive power of the convex surface and the refractive power of the concave surface are opposite. The light is emitted from the microlens 44 as parallel light.

  In FIG. 5, solid arrows indicate parallel light incident parallel to the optical axis of the microlens 44, and broken arrows indicate parallel light incident obliquely with respect to the optical axis of the microlens 44. As shown in FIG. 5, in the case where substantially parallel light emitted from a light source such as a lamp is incident on the microlens 44, an optical component is used so that the light does not strike the liquid crystal driving circuit of the liquid crystal device. The positive refractive power of the first refractive surface (convex surface) in the microlens 44 causes the substantially parallel light incident on the microlens 44 to converge, so that the light does not concentrate on a specific part of the liquid crystal phase of the liquid crystal device, and The parallel light from the microlens 44 is converted into the liquid crystal phase of the liquid crystal device by the negative refractive power of the second refracting surface (concave surface) in the microlens 44 so that the emission angle of the light emitted from the liquid crystal device is reduced. Can be launched. That is, since light does not concentrate on a specific part of the liquid crystal phase of the liquid crystal device, the deterioration of the liquid crystal phase in the liquid crystal device can be greatly reduced, and the lifetime of the liquid crystal device can be significantly increased as compared with the conventional liquid crystal device. The light emitted from the liquid crystal device with respect to both parallel light incident parallel to the optical axis of the microlens 44 and parallel light incident obliquely to the optical axis of the microlens 44 is substantially parallel light, The light emission angle is small. Therefore, the light transmitted through the adjacent microlenses and passing through the liquid crystal phase can be greatly reduced from mixing with each other. It is possible to greatly reduce the deterioration of the characteristics and contrast. Therefore, the light incident on the optical element can be used more effectively. Furthermore, the design of the collimating lens for further collimating the substantially parallel light emitted from the liquid crystal device can be greatly facilitated.

  The optical element substrate 42 and the microlens 44 as an optical component are each made of, for example, low expansion glass such as quartz or neoceram. The microlens 44 is directly bonded to the optical element substrate 42 and glass. Having a joining surface. Since the optical element substrate 42 and the microlens 44 are directly bonded to the glass without using a resin adhesive having a larger thermal expansion coefficient than that of glass, the durability or heat resistance of the optical element against temperature change is achieved. Thus, it is possible to provide an optical element that is stable and stable over time. Note that an antireflection film may be provided on the microlens 44 as an optical component. A space 46 between the optical element substrate 42 and the microlens 44 as an optical component is vacuum or air. Since the space 46 between the optical element substrate 42 and the microlens 44 as an optical component is vacuum or air, the radii of curvature of the first and second refracting surfaces (convex surface and concave surface) of the microlens 44 are compared. The design of the microlens array 44 can be facilitated.

  The light incident on the liquid crystal phase 24 irradiates the liquid crystal molecules 26, and the alignment of the liquid crystal molecules 26 is controlled by the liquid crystal driving circuit 28. Then, by controlling the voltage applied to the liquid crystal driving circuit in accordance with the desired image information, the liquid crystal molecules 26 can be properly aligned, and the desired image information can be imparted to the light passing through the liquid crystal phase 24. The light to which the image information emitted from the liquid crystal substrate 22 side through the liquid crystal phase 24 is added is collimated by a collimator lens (not shown) and enters a projection lens (not shown) as parallel light. And the light to which image information was given is projected on a screen by a projection lens.

  FIG. 6 is a diagram for explaining another example of a liquid crystal device including an optical element according to the third aspect of the present invention. Regarding the optical element of the liquid crystal device shown in FIG. 6, the first refractive surface (convex surface) and the second refractive surface (concave surface) of the microlens as the optical component in the optical element of the liquid crystal device shown in FIG. , Respectively, including a substantial plane as a third plane and a substantial plane as a fourth plane. That is, the flat surface is provided on both the convex central portion and the concave central portion of the microlens 44. Therefore, as shown in FIG. 6, the parallel light passing through the convex spherical surface portion of the microlens 44 represented by the solid arrow is converged by the positive refractive power in the convex spherical surface portion of the microlens 44, and the microlens. The light diverges by the negative refractive power in the concave spherical surface 44 and is emitted toward the liquid crystal phase 24 as parallel light. Further, the parallel light that passes through the convex and concave plane portions of the microlens 44 represented by the broken arrow is not refracted by the surface of the microlens 44 and passes through the microlens 44 as it is.

  7A to 7F are views for explaining an example of a method for producing an optical element according to the third aspect of the present invention. More specifically, FIGS. 7A to 7F describe a method for manufacturing the optical element according to the third embodiment of the present invention shown in FIG.

  First, as shown in FIG. 7A, a photosensitive material (photoresist) 34 for semiconductor is applied to an optical glass material 32 of low expansion glass such as quartz or neoceram having a parallel plane plate form, and optical A layer of photosensitive material 34 is formed on a plane parallel plate of glass material 32. Next, a density distribution mask 36 designed in advance corresponding to the shape of the first refractive surface (convex surface) in the plurality of microlenses 44 shown in FIG. 5 is positioned with respect to the layer of the photosensitive material 34. The density distribution mask has an exposure region that is divided into unit cells having an appropriate shape and size corresponding to the shape of the first refractive surface (convex surface) of the plurality of microlenses 44 without a gap. Further, for the light shielding pattern in the unit cell of the density distribution mask, the transmitted light amount or the light shielding amount of the unit cell is set to a value that can realize a desired pattern of the photosensitive material. Next, light with which the photosensitive material 34 reacts is irradiated onto the layer of the photosensitive material 34 on the plane parallel plate of the optical glass material 32 through the density distribution mask 36, and the photosensitive material is subjected to a normal photolithography process. 34 layers are developed and cured.

  As a result, as shown in FIG. 7B, the photosensitive material 34 having a shape corresponding to the shape of the first refractive surface (convex surface) of the plurality of microlenses 44 is formed on the plane parallel plate of the optical glass material 32. A layer is formed.

  Next, as shown in FIG. 7 (c), a plane parallel plate of the optical glass material 32 according to the shape corresponding to the shape of the first refractive surface (convex surface) of the plurality of microlenses 44 in the layer of the photosensitive material 34. Etch. Here, the etching is performed on the parallel flat plate of the optical glass material 32 provided with the layer of the photosensitive material 34, using a semiconductor dry etching apparatus, and on the surface of the parallel flat plate of the optical glass material 32. Both the layer of photosensitive material 34 and the plane parallel plate of optical glass material 32 are etched by impinging the etching species in the vertical direction. Thus, from the plane-parallel plate portion of the optical glass material 32 corresponding to the thin portion of the photosensitive material 34 layer to the plane-parallel plate portion of the optical glass material 32 corresponding to the thick portion of the photosensitive material 34 layer. Etching is performed sequentially. In this way, a microlens array of the optical glass material 32 as an optical component having the shape of the first refractive surface (convex surface) of the plurality of microlenses 44 is formed.

  In (dry) etching, if the etching selectivity is changed, the etching can be achieved with a shape (different height, spherical surface, aspherical surface, etc.) different from the shape of the photosensitive material. Further, when the time point at which dry etching is finished is changed, that is, when the etching time is changed, the height of the photosensitive material to be etched changes.

As a specific method of etching, the plane parallel plate of the optical glass material 32 provided with the layer of the photosensitive material 34 is cooled to 5 ° C., and etching is performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. . Here, for example, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 10 sccm, the flow rate of Ar gas is 5 sccm, the pressure of the mixed gas is 25 mTorr, and the bias is 450 W, the upper power is 2.0 kW, the etching rate is 5 μm / min, and the processing time is 4.5 seconds. When C ₄ F ₈ gas is used, the flow rate of C ₄ F ₈ gas is 100 sccm, the pressure of the gas is 20 mTorr, the bias is 5 W, and the upper power is 1.8 kW. Yes, the processing time is 3-4 minutes.

  Next, as shown in FIG. 7 (d), the surface on which the first refractive surface (convex surface) of the optical glass material 32 on which the first refractive surfaces (convex surfaces) of the plurality of microlenses 44 are formed is formed. A semiconductor photosensitive material (photoresist) 34 is applied to the opposite surface, and a layer of the photosensitive material 34 is formed on a plane parallel plate of the optical glass material 32. Next, the density distribution mask 36 designed in advance corresponding to the shape of the second refractive surface (concave surface) in the plurality of microlenses 44 shown in FIG. 5 is positioned with respect to the layer of the photosensitive material 34. The density distribution mask has an exposure region that is divided into unit cells having an appropriate shape and size corresponding to the shape of the second refractive surface (concave surface) of the plurality of microlenses 44 without any gap. Further, for the light shielding pattern in the unit cell of the density distribution mask, the transmitted light amount or the light shielding amount of the unit cell is set to a value that can realize a desired pattern of the photosensitive material. Next, light with which the photosensitive material 34 reacts is irradiated onto the layer of the photosensitive material 34 on the plane parallel plate of the optical glass material 32 through the density distribution mask 36, and the photosensitive material is subjected to a normal photolithography process. 34 layers are developed and cured.

  As a result, as shown in FIG. 7E, the photosensitive material 34 having a shape corresponding to the shape of the second refracting surfaces (concave surfaces) of the plurality of microlenses 44 is formed on the plane parallel plate of the optical glass material 32. A layer is formed.

  Next, as shown in FIG. 7 (f), the plane parallel plate of the optical glass material 32 according to the shape corresponding to the shape of the second refractive surface (concave surface) of the plurality of microlenses 44 in the layer of the photosensitive material 34. Etch. Here, the etching is performed on the parallel flat plate of the optical glass material 32 provided with the layer of the photosensitive material 34, using a semiconductor dry etching apparatus, and on the surface of the parallel flat plate of the optical glass material 32. Both the layer of photosensitive material 34 and the plane parallel plate of optical glass material 32 are etched by impinging the etching species in the vertical direction. Thus, from the plane-parallel plate portion of the optical glass material 32 corresponding to the thin portion of the photosensitive material 34 layer to the plane-parallel plate portion of the optical glass material 32 corresponding to the thick portion of the photosensitive material 34 layer. Etching is performed sequentially. In this manner, a microlens array of the optical glass material 32 as an optical component having the shape of the second refractive surface (concave surface) in the plurality of microlenses 44 is formed.

  In this way, an optical element including a plurality of microlenses 44 as optical components having a first refractive surface (convex surface) and a second refractive surface (concave surface) as shown in FIG. 5 can be formed. .

  Note that the first refracting surface (convex surface) and / or the second refracting surface (concave surface) of the plurality of microlenses 44 may be applied to the second refracting surface (concave surface) in a thin film forming step as necessary (reflected with respect to light having a wavelength of visible light). An antireflection film may be provided. Here, in the thin film formation step, a solution containing a material for the vacuum deposition method, the CVD method, the sputtering method, and the antireflection film 38 is applied by spin coating, and the applied solution is heated to form the antireflection film 38. Either method may be used.

  Further, a microlens array including a plurality of microlenses 44 having a first refracting surface (convex surface) and a second refracting surface (concave surface) is bonded to the optical element substrate 42 of the optical glass 23 by direct glass bonding. Also good. In direct glass bonding, 1% hydrofluoric acid is applied to a bonding surface of a microlens array including a plurality of microlenses 44 having a first refractive surface (convex surface) and a second refractive surface (concave surface) by a tampo method or a spinner method. Is applied thinly, and the optical element substrate 42 of the optical glass 32 is brought into contact in the air. Next, a pressure of about 1.0 MPa is applied to the bonding surface of the microlens array brought into contact with each other and the corresponding surface of the optical element substrate 42 of the optical glass 32 and heated at 60 ° C. for 1 hour. Thereafter, the microlens array and the optical element substrate 42 are washed with an organic solvent and dried in a vacuum. In this way, an optical element including a plurality of microlenses 44 as an optical component having a first refracting surface (convex surface) and a second refracting surface (concave surface) as shown in FIG. 5 can be obtained. it can.

  In addition, about the method of manufacturing the optical element which is the 3rd aspect of this invention shown in FIG. 6, while using the method of manufacturing the optical element which is the 3rd aspect of this invention shown in FIG. Using the method of forming the joint surface of the microlens array in the method of manufacturing the optical element according to the first embodiment of the present invention described with reference to FIG. 4, a flat surface is formed at the central portion of the convex surface and the concave surface of the microlens 44. Can be formed.

  A microlens array comprising microlenses having a substantially flat joining surface and a curved surface (aspherical) optical surface, wherein the antireflection film is provided on the optical surface, and the antireflection film is provided on the joining surface. I made a microlens array that I can't.

  First, OFPR-800 (manufactured by Tokyo Ohka), which is a photosensitive material (photoresist), is applied to a quartz parallel plane plate having a refractive index of 1.42 with respect to a wavelength of 550 nm. A layer of photosensitive material was formed. Next, the photosensitive material layer is irradiated with ultraviolet light through a density distribution mask designed in accordance with the shape of the microlens array, and the photosensitive material layer is developed and cured by a normal photolithography process. Treated. As a result, a layer of photosensitive material having the shape of a microlens array was formed on a parallel plane plate made of quartz.

  Next, according to the shape of the microlens array in the photosensitive material layer, the photosensitive material layer and the parallel plane plate of quartz were dry etched using a semiconductor dry etching apparatus. Here, the portion of the quartz plane parallel plate corresponding to the optical surface of the microlens array is etched, and the portion of the plane parallel quartz plate corresponding to the bonding surface of the microlens array is not etched. Stopped. In this way, a quartz microlens array having a substantially flat joining surface and a curved (aspheric) optical surface was formed.

As a specific method of etching, a quartz parallel flat plate provided with a photosensitive material layer was cooled to −20 ° C., and etching was performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. Here, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 10 sccm, the flow rate of Ar gas is 5 sccm, the pressure of the mixed gas is 45 mTorr, and the bias is 450 W. The upper power was 2.0 kW, the etching rate was 0.6 μm / min, and the processing time was 11 minutes.

For the quartz microlens array obtained, the optical surface of the microlens is z (h) = (h ² / R) / (1+ (1− (1 + κ) (h / R) ² ) ^1/2. ) + A ₄ h ⁴ + A ₆ h ⁶ +... + A _k h ^k , where a is a rotationally symmetric aspherical surface, where h is the height from the optical axis of the lens, and z (h) is the height h Is a distance from a plane that includes a virtual intersection of the optical axis of the lens and the optical surface of the lens and is perpendicular to the optical axis of the lens, R is a radius of curvature of the optical surface of the lens, and κ is , The conic coefficient of the optical surface of the lens, A _k is the k-order aspherical coefficient of the optical surface of the lens, and k is an even number of 4 or more.) In this embodiment, the optical surface The curvature radius R of the optical surface is 7.25 × 10 ⁻³ mm, and the conic coefficient κ of the optical surface is −7.76 × 10 ⁻¹ . Yes, the fourth-order aspheric coefficient A ₄ of the optical surface is −2.01 × 10 ⁵ mm ⁻³ , and the sixth-order aspheric coefficient A ₆ of the optical surface is 1.26 × 10 ⁹ mm ^−5. The 8th-order or higher aspherical coefficient of the optical surface is zero. The diameter of the optical surface of the microlens was 15.5 μm, the diameter of the bonding surface of the microlens was 4.2 μm, and the height of the microlens was 6.5 μm. The pitch of the microlenses in the microlens array was 15.5 μm.

  Next, the quartz microlens array with the photosensitive material layer remaining on the joining surface of the quartz microlens array having a substantially flat joining surface and a curved (aspheric) optical surface. An antireflection film for preventing reflection of light having a wavelength of visible light was formed on the layer of the photosensitive material remaining on the optical surface and the bonding surface of the microlens array using a vacuum deposition method. .

The formed antireflection film consists of four layers. Assuming λ = 550 nm, from the microlens side, the first layer is a layer of SiO ₂ having a refractive index of 1.450 and a thickness of λ / 4, and the second layer is 1.630. A layer of alumina (Al ₂ O ₃ ) having a refractive index and a thickness of λ / 4, the third layer is titanium oxide (TiO ₂ ) having a refractive index of 2.300 and a thickness of λ / 2 And the fourth layer was a layer of SiO ₂ having a refractive index of 1.450 and a thickness of λ / 4. FIG. 8 is a diagram for explaining the reflection characteristics of the antireflection film formed in this example. FIG. 8A is a diagram showing the reflectance / transmittance with respect to wavelengths from 350 nm to 850 nm, and FIG. These are the detailed figures of the reflectance with respect to the wavelength from 350 nm to 850 nm. In FIG. 8, a curve R indicates the reflectance, and a curve T indicates the transmittance. As shown in FIGS. 8A and 8B, the antireflection film formed in this example exhibits a reflectance of 0.5% or less with respect to light having a wavelength from 400 nm to 680 nm. The transmittance is 5% or more. The incident angle of light with respect to the antireflection film is 0 °.

  Next, a quartz microlens array in which an antireflection film is formed on the optical surface and the photosensitive material layer is formed by using a lift-off method. The layer of the photosensitive material remaining on the bonded surface of the quartz microlens array was removed by treatment with a stripping solution 105 (manufactured by Tokyo Ohka Kogyo Co., Ltd.).

  Thus, a microlens array comprising microlenses having a substantially flat joining surface and a curved (aspheric) optical surface, the antireflection film being provided on the optical surface, A microlens array without an antireflection film was obtained. The substrate thickness of the obtained microlens array was 300 μm.

  Finally, the joining surface of the quartz microlens array and the quartz cover glass having a thickness of 1000 μm were joined by glass direct joining. That is, 1% hydrofluoric acid is thinly applied to the joint surface of the quartz microlens array by the tampo method, the quartz cover glass is brought into contact with the air, and then the quartz microlens arrays are brought into contact with each other. A pressure of about 1.0 MPa was applied to the face and the corresponding face of the quartz cover glass and heated at 60 ° C. for 1 hour. Thereafter, the microlens array and the cover glass were washed with acetone and dried in a vacuum.

  In this way, an optical element including a microlens array having a cover glass, a flat joint surface directly joining the cover glass and the glass, and an aspheric optical surface provided with an antireflection film could be obtained.

  The optical characteristics of a liquid crystal device in which the optical element obtained in this example was attached to a 0.8 inch liquid crystal projector panel were simulated. Here, the 0.8-inch liquid crystal projector panel is a liquid crystal driving circuit and has a black matrix having a square opening. The size of the opening of the black matrix was 15.0 × 15.0 μm. The intensity distribution of the light incident on the optical element obtained in this example with respect to the incident angle (with respect to the cover glass) has a maximum intensity at an incident angle of about ± 7 ° and an incident angle of about ± 20 °. An M-type distribution having zero intensity.

  All the light transmitted through the optical element obtained in this example passed through the aperture of the black matrix.

The transmission efficiency of the liquid crystal device including the optical element obtained in this example was compared with the transmission efficiency of the liquid crystal device including the optical element of the comparative example. The optical element of the comparative example includes a micro lens array (thickness of substrate: 50 μm) of Neoceram (manufactured by Nippon Electric Glass Co., Ltd.) and a cover glass (thickness: 1050 μm) of Neoceram. Bonded with a layer of agent (refractive index 1.45: thickness 2.5 μm). The microlens of the microlens array is a rotationally symmetric aspherical surface represented by the above formula, the aspherical curvature radius R is 6.5 μm, and the aspherical cone coefficient κ is −5.26. The fourth-order aspheric coefficient A ₄ of the optical surface is 6.30 × 10 ⁵ mm ⁻³ , and the sixth-order aspheric coefficient A ₆ of the optical surface is −3.99 × 10 ⁹ mm ⁻⁵ . Yes, the aspherical coefficient of the 8th order or higher of the optical surface is zero. The height of the microlens was 7.0 μm, and the diameter and pitch of the microlens were 14.0 μm. The optical element of the comparative example was attached to a 0.7-inch liquid crystal projector panel. The size of the black matrix opening of the 0.7-inch liquid crystal projector panel was 13.5 × 13.5 μm.

  As a result, when the transmission efficiency of the liquid crystal device including the optical element of the comparative example is 100%, the transmission efficiency of the liquid crystal device including the optical element obtained in this example is 102%. The transmission efficiency of the obtained liquid crystal device including the optical element was higher than the transmission efficiency of the liquid crystal device including the optical element of the comparative example. In the optical element of the comparative example, the transmission efficiency of the liquid crystal device including the optical element in which the microlens array and the cover glass are bonded by direct glass bonding was 98%.

  A microlens array comprising a microlens having an optical surface that is a substantially flat surface and a curved surface (aspheric surface) provided on the outer periphery thereof, and an antireflection film is provided on the entire substantially flat surface and the optical surface. A microlens array was fabricated.

  First, OFPR-800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), a photosensitive material (photoresist), is applied to a parallel flat plate of Neoceram (manufactured by Nippon Electric Glass Co., Ltd.) having a refractive index of 1.5417 for a wavelength of 550 nm. A layer of photosensitive material was formed on a parallel plane plate of neoceram. Next, the photosensitive material layer is irradiated with ultraviolet light through a density distribution mask designed in accordance with the shape of the microlens array, and the photosensitive material layer is developed and cured by a normal photolithography process. Treated. As a result, a layer of photosensitive material having the shape of a microlens array was formed on a parallel plane plate of Neoceram.

  Next, according to the shape of the microlens array in the photosensitive material layer, the photosensitive material layer and the neo-serum parallel plane plate were dry etched using a semiconductor dry etching apparatus. Here, the portion of the quartz plane parallel plate corresponding to the optical surface of the microlens array is etched, and the portion of the plane parallel quartz plate corresponding to the bonding surface of the microlens array is not etched. Stopped. In this manner, a neo-ceram microlens array having an optical surface that is a substantially flat surface and a curved surface (aspheric surface) provided on the outer periphery thereof was formed.

As a specific method of etching, a neoceram parallel plane plate provided with a layer of a photosensitive material was cooled to −20 ° C., and etching was performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. Here, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 10 sccm, the flow rate of Ar gas is 5 sccm, the pressure of the mixed gas is 45 mTorr, and the bias is 450 W. The upper power was 2.0 kW, the etching rate was 0.6 μm / min, and the processing time was 11 minutes.

Regarding the obtained neo-ceram microlens array, the optical surface of the microlens is z (h) = (h ² / R) / (1+ (1− (1 + κ) (h / R) ² ) ^1/2 ) + A ₄ h ⁴ + A ₆ h ⁶ +... + A _k h ^k , where a is a rotationally symmetric aspherical surface, where h is the height from the optical axis of the lens, and z (h) is the height h Is a distance from a plane that includes a virtual intersection of the optical axis of the lens and the optical surface of the lens and is perpendicular to the optical axis of the lens, R is a radius of curvature of the optical surface of the lens, and κ is , The conic coefficient of the optical surface of the lens, A _k is the k-order aspherical coefficient of the optical surface of the lens, and k is an even number of 4 or more.) In this embodiment, the optical surface The curvature radius R of the optical surface is 5.9 × 10 ⁻³ mm, and the conic coefficient κ of the optical surface is −2.92. The fourth-order aspheric coefficient A ₄ of the optical surface is 8.66 × 10 ⁵ mm ⁻³ , and the sixth-order aspheric coefficient A ₆ of the optical surface is −5.93 × 10 ⁹ mm ⁻⁵ . The aspherical coefficient of the 8th order or higher of the optical surface is zero. The diameter of the optical surface of the microlens was 14.0 μm, the diameter of the bonding surface of the microlens was 3.8 μm, and the height of the microlens was 6.8 μm. Further, the pitch of the microlenses in the microlens array was 14.0 μm.

  Next, the layer of the photosensitive material remaining on the neoceram microlens array having an optical surface which is a substantially flat surface and a curved surface (aspheric surface) provided on the outer periphery thereof is treated with a stripping solution 105 (manufactured by Tokyo Ohka Kogyo Co., Ltd.). Removed.

  Next, a vacuum is applied over the entire optical surface that is a substantially flat surface and a curved surface (aspheric surface) of a neoceram microlens array having an optical surface that is a substantially flat surface and a curved surface (aspheric surface) provided on the outer periphery thereof. Using a vapor deposition method, an antireflection film for preventing reflection of light having a wavelength of visible light was formed.

The formed antireflection film consists of four layers. Assuming λ = 550 nm, from the microlens side, the first layer is a layer of SiO ₂ having a refractive index of 1.450 and a thickness of λ / 4, and the second layer is 1.630. A layer of alumina (Al ₂ O ₃ ) having a refractive index and a thickness of λ / 4, the third layer is titanium oxide (TiO ₂ ) having a refractive index of 2.300 and a thickness of λ / 2 And the fourth layer was a layer of SiO ₂ having a refractive index of 1.450 and a thickness of λ / 4. FIG. 9 is a diagram for explaining the reflection characteristics of the antireflection film formed in this example. FIG. 9A is a diagram showing the reflectance / transmittance for wavelengths from 350 nm to 850 nm, and FIG. These are the detailed figures of the reflectance with respect to the wavelength from 350 nm to 850 nm. In FIG. 9, a curve R indicates the reflectance, and a curve T indicates the transmittance. As shown in FIGS. 9A and 9B, the antireflection film formed in this example exhibits a reflectance of 0.5% or less with respect to light having a wavelength from 400 nm to 680 nm, and is 99. The transmittance is 5% or more. The incident angle of light with respect to the antireflection film is 0 °. The microlens array obtained in this example is slightly different from the microlens array obtained in Example 1 with respect to the reflectance with respect to light having a wavelength of 500 nm.

  Thus, a microlens array comprising microlenses having an optical surface that is a substantially flat surface and a curved surface (aspherical surface) provided on the outer periphery thereof, and the antireflection is applied to the entire substantially flat surface and the optical surface. A microlens array provided with a film was obtained. The substrate thickness of the obtained microlens array was 300 μm. Here, the antireflection film provided on the substantially flat surface of the microlens array is a joint surface that is substantially flat.

  Next, the same antireflection film as the antireflection film provided on the microlens array was formed on the neoceram cover glass.

Finally, the anti-reflection coating joint surface provided on the neo-serum microlens array and the neo-serum cover glass having a thickness of 1000 μm were joined by glass direct joining. That is, 1% hydrofluoric acid was thinly applied to the joint surface of the anti-reflection film provided on the neo-ceram microlens array by the tampo method, the neo-serum cover glass was brought into contact with the air, and then brought into contact with each other. A pressure of about 1.0 MPa was applied to the joint surface of the antireflection film provided on the neo-ceram microlens array and the corresponding surface of the neo-delam cover glass and heated at 60 ° C. for 1 hour. Thereafter, the microlens array and the cover glass were washed with acetone and dried in a vacuum. Since the film having the antireflection film bonding surface provided on the microlens array and the film having the antireflection film bonding surface provided on the cover glass are made of SiO ₂ , the reflection provided on the microlens array is provided. The anti-reflection film can be directly bonded to the anti-reflection film provided on the cover glass.

  Thus, an optical element including a cover glass, a microlens array having an optical surface, and an antireflection film provided on the microlens array and having a bonding surface directly bonded to the cover glass and the glass could be obtained.

  The optical characteristics of a liquid crystal device in which the optical element obtained in this example was attached to a 0.7-inch liquid crystal projector panel were simulated. Here, the 0.8-inch liquid crystal projector panel is a liquid crystal driving circuit and has a black matrix having a square opening. The size of the black matrix opening was 13.5 × 13.5 μm. The intensity distribution of the light incident on the optical element obtained in this example with respect to the incident angle (with respect to the cover glass) has a maximum intensity at an incident angle of about ± 7 ° and an incident angle of about ± 20 °. An M-type distribution having zero intensity.

  All the light transmitted through the optical element obtained in this example passed through the aperture of the black matrix.

The transmission efficiency of the liquid crystal device including the optical element obtained in this example was compared with the transmission efficiency of the liquid crystal device including the optical element of the comparative example. The optical element of the comparative example includes a micro lens array (thickness of substrate: 50 μm) of Neoceram (manufactured by Nippon Electric Glass Co., Ltd.) and a cover glass (thickness: 1050 μm) of Neoceram. Bonded with a layer of agent (refractive index 1.45: thickness 2.5 μm). The microlens of the microlens array is a rotationally symmetric aspherical surface represented by the above formula, the aspherical curvature radius R is 6.5 μm, and the aspherical cone coefficient κ is −5.26. The fourth-order aspheric coefficient A ₄ of the optical surface is 6.30 × 10 ⁵ mm ⁻³ , and the sixth-order aspheric coefficient A ₆ of the optical surface is −3.99 × 10 ⁹ mm ⁻⁵ . Yes, the aspherical coefficient of the 8th order or higher of the optical surface is zero. The height of the microlens was 7.0 μm, and the diameter and pitch of the microlens were 14.0 μm. The optical element of the comparative example was attached to a 0.7-inch liquid crystal projector panel. The size of the black matrix opening of the 0.7-inch liquid crystal projector panel was 13.5 × 13.5 μm.

  As a result, when the transmission efficiency of the liquid crystal device including the optical element of the comparative example is 100%, the transmission efficiency of the liquid crystal device including the optical element obtained in this example is 102%. The transmission efficiency of the obtained liquid crystal device including the optical element was higher than the transmission efficiency of the liquid crystal device including the optical element of the comparative example. In the optical element of the comparative example, the transmission efficiency of the liquid crystal device including the optical element in which the microlens array and the cover glass are bonded by direct glass bonding was 98%.

  In a microlens array including a plurality of microlenses having a first refractive surface (spherical convex surface) and a second refractive surface (spherical concave surface), the refractive power of the first refractive surface and the refraction of the second refractive surface The forces produced microlens arrays having opposite signs and substantially equal absolute values.

  First, OFPR-800 (Tokyo), a photosensitive material (photoresist), is applied to a parallel flat plate (thickness: 500 μm) of Neoceram (manufactured by Nippon Electric Glass Co., Ltd.) having a refractive index of 1.5417 for a wavelength of 550 nm. Oka) was applied to form a layer of photosensitive material on a neoceram parallel flat plate. Next, the layer of the photosensitive material is irradiated with ultraviolet light through a concentration distribution mask designed corresponding to the shape of the first refractive surface (spherical convex surface) in the microlens included in the microlens array, The photosensitive material layer was developed and cured by a normal photolithography process. As a result, a layer of a photosensitive material having the shape of the first refracting surface (spherical convex surface) of the microlens included in the microlens array was formed on a parallel plane plate of neoceram.

  Next, according to the shape of the first refracting surface (spherical convex surface) of the microlens included in the microlens array in the photosensitive material layer, a semiconductor dry etching apparatus is used to parallel the photosensitive material layer and neoserum. The flat plate was dry etched. In this way, a neoceram microlens array having a first refractive surface (spherical convex surface) was formed.

As a specific method of etching, a neoceram parallel plane plate provided with a layer of a photosensitive material was cooled to −20 ° C., and etching was performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. Here, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 5 sccm, the flow rate of Ar gas is 15 sccm, the pressure of the mixed gas is 25 mTorr, and the bias is 450 W. The upper power was 2.0 kW, the etching rate was 0.2 μm / min, and the processing time was 5 minutes.

  In the obtained neoceram microlens array, the radius of curvature of the first refractive surface (spherical convex surface) of the microlens is 700 μm, and the diameter of the first refractive surface of the microlens is 12.0 μm. Met. The pitch of the microlenses in the microlens array was 12.0 μm.

  Next, OFPR-800 is a photosensitive material (photoresist) on the surface opposite to the first refracting surface in the neo-ceram optical element in which the microlens array having the first refracting surface (spherical convex surface) is formed. (Manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied, and a layer of photosensitive material was formed on the surface opposite to the first refracting surface in the optical element of Neoserum. Next, the layer of the photosensitive material is irradiated with ultraviolet light through a concentration distribution mask designed corresponding to the shape of the second refractive surface (spherical concave surface) in the microlens included in the microlens array, The photosensitive material layer was developed and cured by a normal photolithography process. As a result, a layer of photosensitive material having the shape of the second refracting surface (spherical concave surface) of the microlens included in the microlens array is formed on the surface opposite to the first refracting surface of the neo-ceram optical element. It was done.

  Next, according to the shape of the second refracting surface (spherical concave surface) in the microlens included in the microlens array in the photosensitive material layer, using the semiconductor dry etching apparatus, the photosensitive material layer and neoserum optics The surface opposite to the first refracting surface of the device was dry etched. In this manner, a neoceram microlens array including a plurality of microlenses having a first refracting surface (spherical convex surface) and a second refracting surface (spherical concave surface) was formed.

As a specific method of etching, a neoceram parallel plane plate provided with a layer of a photosensitive material was cooled to −20 ° C., and etching was performed with a mixed gas of CF ₄ , CHF ₃ , and Ar. Here, the flow rate of CF ₄ gas is 50 sccm, the flow rate of CHF ₃ gas is 5 sccm, the flow rate of Ar gas is 15 sccm, the pressure of the mixed gas is 25 mTorr, and the bias is 450 W. The upper power was 2.0 kW, the etching rate was 0.2 μm / min, and the processing time was 5 minutes.

  In the obtained neoceram microlens array, the radius of curvature of the second refractive surface (spherical concave surface) of the microlens is 500 μm, and the diameter of the second refractive surface of the microlens is 11.0 μm. The thickness of the center of the microlens was 500 μm. Further, the pitch of the microlenses in the microlens array was 700 μm. Furthermore, a bonding surface for bonding to the cover glass was provided on the outer periphery of the second refractive surface of the microlens.

  Next, the joining surface provided on the neo-ceram microlens array and the neo-serum cover glass (thickness: 1 mm) were joined by direct glass joining in a vacuum. That is, 1% hydrofluoric acid is thinly applied to the joint surface provided in the neoceram microlens array by a tampo method, the neoceram cover glass is brought into contact in a vacuum, and then the neoceram microlenses are brought into contact with each other. A pressure of about 1.0 MPa was applied to the joint surface provided in the array and the corresponding surface of the neo-deram cover glass and heated at 60 ° C. for 1 hour. Thereafter, the microlens array and the cover glass were washed with acetone and dried in a vacuum. Finally, the cover glass was polished until the cover glass had a thickness of 25 μm.

  In this manner, a neoceram microlens array including a plurality of microlenses having a first refracting surface (spherical convex surface) and a second refracting surface (spherical concave surface), and an optical element including a cover glass can be obtained. did it.

  In addition, in the optical element described above, combinations of the first refractive surface (spherical convex surface) and the second refractive surface (spherical concave surface) of the microlens are 600 μm and 400 μm, respectively, as shown in Table 1. Optical elements changed to 800 μm and 600 μm, 900 μm and 700 μm, and 1000 μm and 800 μm were manufactured.

  Table 1 Curvature radii of the microlenses fabricated in this example and their optical characteristics

本実施例で得られた光学素子を、それぞれ、０．７インチ液晶プロジェクタ用パネルに取り付けた液晶デバイスの光学特性を測定した。ここで、０．７インチ液晶プロジェクタ用パネルは、液晶駆動回路であると共に正方形の開口を有するブラックマトリックスを有する。ブラックマトリックスの開口の寸法は、１１．５×１１．５μｍ（開口率：５６．２％（数字の確認をお願いします））とした。また、本実施例で得られた光学素子に入射する光の（カバーガラスに対する）入射角は、約±４°の範囲にあった。

The optical characteristics of a liquid crystal device in which the optical elements obtained in this example were respectively attached to a 0.7-inch liquid crystal projector panel were measured. Here, the 0.7-inch liquid crystal projector panel is a liquid crystal driving circuit and has a black matrix having a square opening. The size of the opening of the black matrix was 11.5 × 11.5 μm (opening ratio: 56.2% (please confirm the numbers)). Further, the incident angle (relative to the cover glass) of the light incident on the optical element obtained in this example was in the range of about ± 4 °.

  All the light transmitted through the optical element obtained in this example passed through the aperture of the black matrix.

  The transmission efficiency of the liquid crystal device including the optical element obtained in this example was compared with the transmission efficiency of the liquid crystal device including the optical element of the comparative example. The optical element of the comparative example was only a cover glass having a thickness of 25 μm.

  As shown in Table 1, assuming that the transmission efficiency of the liquid crystal device including the optical element of the comparative example is 1, the transmission efficiency of the liquid crystal device including the optical element obtained in this example exceeds 1.4. In addition, the transmission efficiency of the liquid crystal device including the optical element obtained in this example was significantly higher than the transmission efficiency of the liquid crystal device including the optical element of the comparative example. In addition, as shown in Table 1, when light was incident on the optical element obtained in this example at an incident angle (with respect to the cover glass) in the range of about ± 4 °, the optical obtained in this example The average value of the emission angles of light emitted from the element was sufficiently smaller than 0.1 °, which is an emission angle that can be regarded as substantially parallel light. For this reason, the optical element which improves the transmission efficiency of an optical element and reduces the mixing of the light which permeate | transmits an adjacent microlens was able to be obtained. That is, when a liquid crystal projector using a liquid crystal device including the optical element of this embodiment is used, deterioration of the liquid crystal molecules is reduced, the durability of the liquid crystal device with respect to light is improved, and the image projected on the screen No contrast reduction or color mixing was observed. In addition, since the microlens manufactured in this example was directly bonded to the cover glass in a vacuum, the optical element of this example showed sufficient heat resistance.

  Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to these embodiments and examples, and the embodiments and examples of the present invention are not limited thereto. Can be changed or modified without departing from the spirit and scope of the present invention.

It is a figure explaining the example of the liquid crystal device containing the optical element which is the 1st aspect of this invention. (A)-(f) is a figure explaining the method to manufacture the optical element which is the 1st aspect of this invention. It is a figure explaining the example of the liquid crystal device containing the optical element which is the 2nd aspect of this invention. (A)-(f) is a figure explaining the method to manufacture the optical element which is the 2nd aspect of this invention. It is a figure explaining one example of the liquid crystal device containing the optical element which is the 3rd aspect of this invention. It is a figure explaining another example of the liquid crystal device containing the optical element which is the 3rd aspect of this invention. It is a figure explaining an example of the method of manufacturing the optical element which is the 3rd aspect of this invention. (A) And (b) is a figure explaining the reflective characteristic of the anti-reflective film formed into a film in Example 1. FIG. (A) And (b) is a figure explaining the reflective characteristic of the anti-reflective film formed into a film in Example 2. FIG. It is a side view which shows the example of the conventional liquid crystal device containing the optical element for condensing the light from a light source to a liquid crystal phase. The example of the optical element for the conventional liquid crystal device disclosed by patent document 1 is shown.

Explanation of symbols

12, 102, 302 Microlens array 14 Antireflection film 16, 304 Cover glass 18 Convex part 22, 202 Liquid crystal substrate 24, 204 Liquid crystal phase 26, 206 Liquid crystal molecule 28, 208 Liquid crystal drive circuit 32 Optical glass 34 Photosensitive material 36 Concentration Distribution mask 38 Antireflection film 42, 104 Optical element substrate 44 Micro lens 46 Space

Claims (22)

In an optical element including a substrate and an optical component having a bonding surface directly bonded to the substrate and an optical surface different from the bonding surface,
An optical element, wherein an antireflection film is provided on the optical surface. The substrate and the optical component each independently comprise a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass;
The optical element according to claim 1, wherein the direct bonding is a glass direct bonding.   The optical element according to claim 1, wherein the bonding surface is a substantially flat surface.   4. The optical element according to claim 1, wherein the optical component further includes a surface that is bonded to the substrate different from the bonding surface. 5.   The optical element according to any one of claims 1 to 4, wherein a space between the substrate and the antireflection film is a vacuum or is made of air.   6. The optical component according to claim 1, wherein the optical component includes an optical component selected from the group consisting of a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens. Optical elements. In an optical element comprising an optical component having a substrate and an optical surface,
Further comprising an antireflection film provided on the optical component;
The optical element, wherein the antireflection film has a joint surface that directly joins the substrate. The substrate and the antireflection film each independently include a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass;
The optical element according to claim 7, wherein the direct bonding is a glass direct bonding.   The optical element according to claim 7, wherein the bonding surface is a substantially flat surface.   The optical element according to claim 7, wherein the antireflection film further includes a surface that is bonded to the substrate different from the bonding surface.   The optical element according to claim 7, wherein a space between the substrate and the antireflection film is a vacuum or is made of air.   12. The optical component includes an optical component selected from the group consisting of a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens. Optical elements. In an optical element comprising an optical component having a first refractive surface,
The optical component further includes a second refractive surface corresponding to the first refractive surface;
The optical element according to claim 1, wherein the first refractive surface has a refractive power with a sign opposite to a sign of a refractive power of the second refractive surface corresponding to the first refractive surface.   14. The optical element according to claim 13, wherein the absolute value of the refractive power of the first refractive surface is substantially equal to the absolute value of the refractive power of the second refractive surface. Further comprising a substrate,
The optical element according to claim 13, wherein the optical component has a bonding surface that is directly bonded to the substrate. The substrate and the optical component each independently comprise a material selected from the group consisting of silicon oxide, silicate, silicate glass, and borosilicate glass;
The optical element according to claim 15, wherein the direct bonding is a glass direct bonding.   The optical element according to any one of claims 13 to 16, wherein a space between the substrate and the optical component is a vacuum or is made of air.   The optical element according to claim 13, wherein the optical component is bonded to the substrate through an adhesive. The optical component further includes a third surface different from the first refractive surface and the second refractive surface, and a fourth surface corresponding to the third surface,
The optical element according to claim 13, wherein the third surface and the fourth surface are substantially flat.   20. The optical component according to claim 13, wherein the optical component includes a component selected from the group consisting of a lens, a lens array, a prism, a diffractive optical element, and a wavefront lens. Optical element.   A liquid crystal device comprising the optical element according to any one of claims 1 to 21 and a liquid crystal.   A liquid crystal projector comprising the liquid crystal device according to claim 21.

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