Optical elements and optical devices

Abstract

To provide an optical device and an optical element, which can realize a suitable optical functional surface.SOLUTION: Provided is an optical element including a glass body characterized by having a colored layer positioned in the inside of the glass body and on an optical functional surface of the optical element. The optical functional surface includes a plurality of translucent surfaces and a plurality of light-shielding surfaces, with each translucent surface and each light-shielding surface alternately arranged, the colored layer having a plurality of colored layers constituting the plurality of light-shielding surfaces. The optical element includes a parallax barrier, and the plurality of colored layers constitute a plurality of light-shielding surfaces of the parallax barrier. The optical element includes a zone plate, and the plurality of colored layers constitute the plurality of light-shielding surfaces of the zone plate. The optical element includes a glass scale of an optical encoder, and the plurality of colored surfaces constitute the plurality of light-shielding surfaces of the glass scale.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to an optical element and an optical device, and more particularly to an optical element having functionality added by colored glass, an optical element partially having a colored layer, and an optical device using the optical element. [Background technology]

[0002] 2. Description of the Related Art Conventionally, optical elements have been known in which a light-shielding pattern is formed on a transparent glass substrate or the like, and which function as a transmission slit or a diffraction element.

[0003] Patent Document 1 discloses a glass substrate unit used in a stereoscopic image display device. This glass substrate unit has a glass substrate, a parallax barrier, a concave-convex portion, and a color filter. The glass substrate has a first surface facing the image display unit of the stereoscopic image display device and a second surface opposite the first surface. The parallax barrier is formed on the second surface of the glass substrate and has a light-shielding portion and a light-transmitting portion. The concave-convex portion is formed on the second surface of the glass substrate at a position facing the light-shielding portion and has light-scattering properties. The color filter is formed on the first surface.

[0004] Patent Document 2 discloses an imaging device having an image sensor, a modulator, an image storage unit, and a signal processing unit. The image sensor converts an optical image captured by a plurality of pixels arranged in an array on an imaging surface into an image signal and outputs the image signal. The modulator is provided on the light-receiving surface of the image sensor and modulates the intensity of light. The modulator also has a first grid pattern consisting of a plurality of concentric circles. The image storage unit temporarily stores the image signal output from the image sensor. The signal processing unit performs image processing on the image signal output from the image storage unit. The signal processing unit also generates a moiré fringe image by modulating the image signal output from the image storage unit with a virtual second grid pattern consisting of a plurality of concentric circles, and changes the size of the concentric circles of the second grid pattern depending on the focus position.

[0005] Patent Document 3 discloses a photoelectric encoder having a light source device that irradiates light, a scale with graduations arranged along the measurement direction, and a light receiving means that receives the light that is irradiated from the light source device and transmitted through the scale. This photoelectric encoder has an anti-reflection member that prevents stray light generated by reflection on the scale from entering the light receiving means. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-168375 [Patent Document 2] International Publication No. 2017 / 149687 Brochure [Patent Document 3] Japanese Patent Application Laid-Open No. 2018-197743 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the optical elements of Patent Documents 1 to 3 have room for improvement in that the configurations and effects of their respective optical functional aspects (for example, the light-shielding portion of the parallax barrier of Patent Document 1, the grating pattern of Patent Document 2, and the scale of Patent Document 3) have not been fully optimized.

[0008] The present invention was completed based on the above-mentioned awareness of the problems, and has an object to provide an optical element and an optical device that can realize suitable optical functions. [Means for solving the problem]

[0009] The optical element of this embodiment is an optical element having a glass body, and a colored layer located inside the glass body and on an optically functional surface of the optical element, the color of the colored layer being a reduced color caused by glass components, and the colored layer having an optical density OD of 2.0 or more at a wavelength of 750 nm. the colored layer is located from the surface to the interior of the glass body and does not reach the rear surface of the glass body, and the thickness of the colored layer from the surface to the interior of the glass body is 1 to 300 μm. It is characterized by the following.

[0010] In the present embodiment, the term "inside the glass body" is used to refer not only to the interior of the glass body as literally stated, but also to the surface of the glass body. That is, the colored layer may be located from the surface to the interior of the glass body, or may be located inside the glass body without being located on the surface of the glass body. As described above, the colored layer may be positioned from the surface to the interior of the glass body, and may not reach the rear surface of the glass body.

[0013] The optically functional surface may have a plurality of light-transmitting surfaces and a plurality of light-shielding surfaces, each of which is arranged adjacent to and alternately with the other, and the colored layer may have a plurality of colored layers that constitute the plurality of light-shielding surfaces.

[0014] In other words, the multiple light-blocking surfaces formed by the multiple colored layers do not exhibit optical functions by themselves, but rather exhibit a predetermined optical function by cooperating with the multiple light-transmitting surfaces that are alternately arranged adjacently. Specific application examples include parallax barriers, zone plates, and glass scales for optical encoders.

[0015] The optical element may have a parallax barrier, and the plurality of colored layers may constitute a plurality of light-blocking surfaces of the parallax barrier.

[0016] The optical element may have a zone plate, and the plurality of colored layers may constitute a plurality of light-blocking surfaces of the zone plate.

[0017] The optical element may have a glass scale (code pattern) of an optical encoder, and the plurality of colored layers may constitute a plurality of light-shielding surfaces of the glass scale.

[0018] The optical element may include at least one of a lens, a parallel plate, a cover glass, an optical filter, a beam splitter, and a prism, and the colored layer may be located on an optically functional surface of at least one of the lens, the parallel plate, the cover glass, the optical filter, the beam splitter, and the prism.

[0019] The optical device of this embodiment includes any one of the optical elements described above. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide an optical element and an optical device that can realize a suitable optical function surface. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing an example of an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an example of an embodiment of the present invention. [Figure 3-1] 1 is a schematic diagram showing an example of an embodiment of the present invention. [Figure 3-2] FIG. 3 is a schematic diagram for explaining the embodiment of FIG. 3-1. [Figure 4] 1 is a schematic diagram showing an example of an embodiment of the present invention. [Figure 5] 1A to 1C are diagrams showing an example of a process for forming a colored pattern on an optical element by using a barrier film. [Figure 6-1] 1 is an image showing a sample in Example 1-1 and a ruler for reference. [Figure 6-2] 1 is an image showing a sample in Example 1-2 and a ruler for reference. [Figure 7-1] 1 is a graph showing the transmittance of a portion of a sample in Example 1-1 that has a colored layer. [Figure 7-2] 10 is a graph showing the transmittance of a portion of a sample having a colored layer in Example 1-2. [Figure 7-3] 10 is a graph showing the transmittance of a portion of a sample having a colored layer in Example 1-3. [Figure 8-1] 10 is a graph showing the transmittance of a portion of the sample in Example 2-1 having a colored layer for each thickness of the metal film. [Figure 8-2] 10 is a graph showing the transmittance of a portion of the sample having a colored layer in Example 2-2 for each thickness of the metal film. [Figure 9]10 is a graph showing the relationship between the thickness of the metal film and the OD for each heat treatment time for the samples in Examples 2-1 and 2-2. [Figure 10] 10 is an image showing a sample in Example 5 and a ruler for reference. [Figure 11] 1A and 1B are diagrams for explaining technical problems of a parallax barrier according to the related art; [Figure 12] 10A and 10B are diagrams for explaining the advantages of the parallax barrier of the present embodiment. [Figure 13] FIG. 1 is a diagram for explaining technical problems of a conventional zone plate. [Figure 14] FIG. 1 is a diagram for explaining the advantages of the zone plate of this embodiment. [Figure 15] 1A and 1B are diagrams for explaining technical problems with glass scales of optical encoders according to conventional technology. [Figure 16] 10A and 10B are diagrams for explaining the advantages of the glass scale of the optical encoder of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] <Definition of Terms> In this specification, the terms "optically functional surface," "light-transmitting surface," and "light-shielding surface" can be read as "optically functional portion," "light-transmitting portion," and "light-shielding portion." Furthermore, the term "colored layer" can be read as "colored portion." Furthermore, the "light-transmitting surface and light-transmitting portion" do not necessarily transmit all of the incident light, but may transmit a portion of the incident light and reflect the other portion.

[0023] <Explanation of the principle> The optical element of this embodiment is an optical element having a glass body, and has a colored layer located inside the glass body and on an optically functional surface of the optical element.

[0024] In this embodiment, the term "inside the glass body" is used to refer not only to the literal interior of the glass body but also to the surface of the glass body. That is, the colored layer may be located from the surface to the interior of the glass body, or may be located inside the glass body without being located on the surface of the glass body. In either case, the colored layer is present in a layered form inside the glass body, absorbing light passing through the glass body to perform a light-blocking function, and absorbing light reflected inside the glass body, thereby making it possible to obtain a good optical element that suppresses the generation of stray light. Furthermore, the colored layer functioning as a light-blocking layer can exert a predetermined optical function in cooperation with layers other than the colored layer (e.g., an adjacent light-transmitting layer).

[0025] First, with reference to Figs. 1 to 10, the principles of how a colored layer is formed inside a glass body, as well as the structure, effects, etc. of the colored layer will be explained.

[0026] In this embodiment, the glass according to this embodiment will be described based on the content ratio of each component expressed in cation %. Therefore, hereinafter, unless otherwise specified, "%" for each content means "cation %."

[0027] The cationic % expression refers to the molar percentage when the total content of all cationic components is 100%. The total content refers to the total content of multiple cationic components (including when the content is 0%). The cationic ratio refers to the ratio (ratio) of the content of each cationic component (including the total content of multiple cationic components) in the cationic % expression.

[0028] The content of glass components can be quantified by known methods, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectroscopy (ICP-MS), etc. In this specification and the present embodiment, a content of 0% of a component means that the component is substantially not contained, and it is acceptable for the component to be contained at an unavoidable impurity level.

[0029] In this specification, unless otherwise specified, the refractive index refers to the refractive index nd at the d line (wavelength 587.56 nm).

[0030] The glass (glass body) according to this embodiment has a colored layer. The colored layer is a colored portion of the glass, and preferably exists in a layer form from the surface of the glass toward the inside. Note that the colored layer may not exist on the surface of the glass, but may exist in a layer form only inside the glass.

[0031] The colored layer is a portion that has a low transmittance for light incident on the glass. Therefore, in the glass according to this embodiment, part or all of the light incident on the glass that enters the colored layer is absorbed, and the intensity of the transmitted light is attenuated compared to light that does not enter the colored layer. In other words, the glass according to this embodiment can have portions with low transmittance and portions with high transmittance.

[0032] In the glass according to this embodiment, the colored layer can be removed by grinding or polishing. In the glass according to this embodiment, the transmittance of the glass after the colored layer is removed is greater than the transmittance before the colored layer is removed.

[0033] In this embodiment, for example, in the case of glass having two opposing surfaces, the colored layer 2 may be provided on only one surface of the glass body 1 as shown in Fig. 1, or may be provided on both surfaces as shown in Fig. 2. In the example of Fig. 1, two colored layers 2 spaced apart in the left-right direction are provided on the upper surface of the glass body 1. In the example of Fig. 2, two colored layers 2 each spaced apart in the left-right direction are provided on the upper and lower surfaces of the glass body 1 (four in total).

[0034] Furthermore, as shown in Figure 3-1, by selectively forming a colored layer on the glass surface, it is possible to block light in the areas where the colored layer is present and transmit light in the areas where the colored layer is not present. For example, by forming the colored layer in a specific pattern, it is possible to impart functions such as slits, apertures, and pinholes to the glass. The specific pattern may be periodic or aperiodic, and may be linear or curved. The glass surface on which the colored layer is formed may be flat or curved.

[0035] In Figure 3-1, light path A does not include the colored layer 2, so it passes from one surface to the other. Path B includes the colored layer 2, so the light is absorbed by the colored layer 2. Furthermore, because the colored layer 2 has the same composition as the uncolored portion, there is no difference in refractive index within the glass, and light is not reflected at the boundary between the colored layer 2 and the uncolored portion. In this case, the same effect as when the colored layer 2 is provided across the entire thickness of the glass, as shown in Figure 3-2, is achieved in terms of light transmission. As is well known, the relationship between the angle of incidence and the angle of refraction at the surface of glass is determined by the refractive index of the glass and the medium (e.g., air) in contact with the glass. This relationship can be taken into account when determining the area where the colored layer is to be formed on the glass surface, the width of the slit, the diameter of the aperture, and other factors.

[0036] As will be described later, the glass according to this embodiment can be used in optical elements. From the viewpoint of use in optical elements, the glass according to this embodiment is preferably an optical glass.

[0037] In the glass according to this embodiment, the colored layer and the non-colored portion have the same glass component composition, although the valence of the glass component (cation) may differ between the colored layer and the non-colored portion.

[0038] In the glass (optical element) according to this embodiment, the refractive index of the colored layer is the same as that of the glass body, so that light incident on the colored layer from outside the glass body, like light incident on the non-colored portion from outside the glass body, exhibits reflection characteristics (Fresnel reflection) that depend on the angle of incidence at the glass surface due to the refractive index of the glass and the refractive index of the medium (e.g., air) in contact with the glass. For this reason, if necessary, an anti-reflection film may be coated on the surface of the optical element, including the colored portion, to reduce reflection on the glass surface.

[0039] The color of the colored layer is preferably a reduction color caused by a glass component, more preferably a reduction color caused by a transition metal. Examples of transition metals include Ti, Nb, W, and Bi. Therefore, the glass according to this embodiment preferably contains, as a glass component, at least one ion selected from the group consisting of Ti ions, Nb ions, W ions, and Bi ions, more preferably Bi ions.

[0040] (Thickness of colored layer) The thickness of the colored layer (for example, the thickness from the surface to the inside of the glass body) is not particularly limited, but is preferably 1 to 300 μm, more preferably 20 to 200 μm, and even more preferably 30 to 150 μm.

[0041] (OD) In the glass according to this embodiment, the spectral transmittance of the colored layer in the wavelength range from the visible range (400 nm to 760 nm) to the infrared range tends to increase as the wavelength increases. On the other hand, the OD of the colored layer tends to decrease as the wavelength increases. OD stands for optical density, and is expressed as a negative value of the common logarithm of the ratio of incident light intensity I0 to transmitted light intensity I, as shown in the following formula: OD=-log 10 (I / I o )

[0042] When the glass according to this embodiment is composed of a colored layer and an uncolored portion with high transmittance in the visible range, the OD of the colored layer is large while the OD of the uncolored portion is small. In measuring OD, when the measurement light passes through both the colored layer and the uncolored portion, the OD of the uncolored portion is sufficiently small so that the OD of the colored layer becomes dominant.

[0043] In addition, when incident light passes through colored layers on both sides of a glass panel that has two opposing surfaces, the OD is approximately twice that of when the same colored layer is provided on only one surface.

[0044] (refractive index) In the glass according to this embodiment, the refractive index nd is preferably 1.70 or more, and more preferably 1.73 or more, 1.75 or more, 1.76 or more, 1.77 or more, 1.78 or more, 1.79 or more, and 1.80 or more in that order. The upper limit of the refractive index nd is not particularly limited, but is usually 2.5, and preferably 2.3.

[0045] Figure 4 shows a glass having two opposing surfaces, with multiple colored layers provided at a specified interval on each opposing surface of the glass, so that the areas without the colored layers function as slits. In this case, if the refractive index of the glass is low, when the angle of incidence of the light beam entering the slit portion is large (the light beam is incident at a shallow angle), the light beam may pass through the adjacent slit, as shown in path C, and the same effect as the element shown in Figure 3-2 may not be obtained. If the refractive index of the glass is high within the above range, the light beam is absorbed by the colored layer formed on the back surface of the glass, as shown in path B, and the light beam does not pass through the adjacent slit, allowing the slit spacing to be narrowed.

[0046] When the glass according to this embodiment is used in an optical element as described below (an example of an optical element applied to other uses), for example, when used in a lens, a higher refractive index of the glass allows for a larger (less pronounced) radius of curvature to be obtained for a lens with the same power (focal length), thereby suppressing the occurrence of various aberrations and reducing the lens thickness. Furthermore, when used in a prism, for example, a higher refractive index of the glass reduces the critical angle, thereby widening the angular range over which normal light (effective light) incident on the reflecting surface is totally reflected, thereby eliminating the need for a total reflection coating.

[0047] (average linear expansion coefficient) In the glass according to this embodiment, the average linear expansion coefficient is preferably 50×10 -7 K -1 That's it, and even more, 60 x 10 -7 K -1 That's it, 70 x 10 -7 K -1 That's it, 75 x 10 -7 K -1 That's it, 80 x 10 -7 K -1 That's it, 85 x 10 -7 K -1 That's it, 90 x 10 -7 K -1 The upper limit of the average linear expansion coefficient is not particularly limited, but is usually 200×10 -7 K -1 and preferably 150×10 -7 K -1 By setting the average linear expansion coefficient within the above range, the strength of the glass can be increased when chemically strengthened.

[0048] The average linear expansion coefficient is measured in accordance with the Japan Optical Glass Industry Association standard JOGIS 08-2003 "Method for measuring thermal expansion of optical glass," except that the diameter of the rod-shaped sample is 5 mm.

[0049] (Acid resistance weight loss rate Da) In the glass according to this embodiment, the grade of the acid resistance weight loss rate Da is preferably 1 to 2, and more preferably 1.

[0050] The acid resistance weight loss rate Da is measured in accordance with the Japan Optical Glass Industry Association standard JOGIS06-2009. Specifically, powdered glass (particle size 425-600 μm) with a weight equivalent to the specific gravity is placed in a platinum cage, immersed in a quartz glass round-bottom flask containing a 0.01 mol / L aqueous solution of nitric acid, and treated in a boiling water bath for 60 minutes. The weight loss rate (%) before and after treatment is measured. Table A shows the grades based on the acid resistance weight loss rate Da.

[0051] [Table A]

[0052] (Glass composition) Non-limiting examples of the composition of the glass according to this embodiment are shown below.

[0053] The glass according to this embodiment is preferably a phosphate glass. Phosphate glass is a glass containing mainly P as a network forming component. 5+ This refers to glass containing P as a network forming component of glass. 5+ , B 3+ , Si 4+ , Al 3+ Here, the term "containing mainly phosphate as a glass network forming component" means that P 5+ The content of B 3+ , Si 4+ , Al 3+ The content of the phosphate glass can increase the degree of coloring in the colored layer.

[0054] In the glass according to this embodiment, P 5+ The lower limit of the content of P is preferably 10%, and more preferably 13%, 15%, 17%, and 20% in that order. 5+ The upper limit of the content is preferably 50%, and more preferably 45%, 40%, 38%, 35%, 33%, and 30% in that order.

[0055] P 5+ is a glass network forming component. 5+ If it contains too much, the melting property will be deteriorated. 5+ The content is preferably in the above range.

[0056] In the glass according to this embodiment, B 3+ The upper limit of the content of B is preferably 30%, and more preferably 25%, 20%, 15%, 13%, and 10% in that order. 3+ The lower limit of the content of B is preferably 0.1%, and more preferably 0.5%, 1%, 3%, and 5% in that order. 3+ The content may be 0%.

[0057] B 3+ is a glass network forming component and has the function of improving the meltability of glass. 3+ If the content of B is too high, the chemical durability tends to decrease. 3+ The content is preferably in the above range.

[0058] In the glass according to this embodiment, P 5+ B content 3+ The content of cation ratio [B 3+ / P 5+ The upper limit of the cation ratio [B 3+ / P 5+ ] may be 0.

[0059] In the glass according to this embodiment, Si 4+ The upper limit of the Si content is preferably 10%, and more preferably 7%, 5%, 3%, 2%, and 1% in that order. 4+ The lower limit of the Si content is preferably 0.1%, and more preferably 0.2%, 0.3%, 0.4%, and 0.5% in that order. 4+ The content may be 0%.

[0060] Si4+ is a glass network-forming component and has the function of improving the thermal stability, chemical durability, and weather resistance of glass. 4+ If the content of Si is too high, the melting property of the glass decreases and the glass raw material tends to remain unmelted. 4+ The content is preferably in the above range.

[0061] In the glass according to this embodiment, Al 3+ The upper limit of the Al content is preferably 10%, and more preferably 7%, 5%, 3%, and 1% in that order. 3+ The content may be 0%.

[0062] Al 3+ has the function of improving the chemical durability and weather resistance of glass. 3+ If the content of Al is too high, the thermal stability of the glass decreases, the glass transition temperature Tg increases, and the melting property tends to decrease. 3+ The content is preferably in the above range.

[0063] In the glass according to this embodiment, P 5+ , B 3+ , Si 4+ and Al 3+ The total content of [P 5+ +B 3+ +Si 4+ +Al 3+ The lower limit of the total content [P 5+ +B 3+ +Si 4+ +Al 3+ The upper limit of [% by mass] is preferably 60%, and more preferably 50%, 45%, 40%, 37%, and 35% in that order.

[0064] The glass according to this embodiment preferably contains a transition metal as a glass component, more preferably contains at least one glass component selected from the group consisting of Ti ions, Nb ions, Bi ions, and W ions, and even more preferably contains Bi ions.

[0065] In the glass according to this embodiment, the lower limit of the Ti ion content is preferably 1%, more preferably 2% and 3% in that order. The upper limit of the Ti ion content is preferably 45%, more preferably 40%, 35%, 30%, 25%, 20%, 15%, and 12% in that order. Here, Ti ions are Ti 4+ , Ti 3+ In addition, it includes all Ti ions with different valences.

[0066] Like Nb ions, W ions, and Bi ions, Ti ions contribute significantly to increasing the refractive index and also have the function of increasing the coloration of the glass. On the other hand, if the content of Ti ions is too high, the meltability of the glass decreases, and the glass raw materials tend to remain unmelted. Therefore, it is preferable that the content of Ti ions is within the above range.

[0067] In the glass according to this embodiment, the lower limit of the Nb ion content is preferably 1%, more preferably 5%, 10%, and 15% in that order. The upper limit of the Nb ion content is preferably 45%, more preferably 40%, 35%, 30%, 25%, 23%, and 20% in that order. Nb ions are Nb 5+ In addition, it includes all Nb ions with different valences.

[0068] Nb ions are a component that contributes to a high refractive index and enhances the coloring of glass. They also function to improve the thermal stability and chemical durability of glass. On the other hand, if the Nb ion content is too high, the thermal stability of the glass tends to decrease. Therefore, it is preferable that the Nb ion content be within the above range.

[0069] In the glass according to this embodiment, the upper limit of the W ion content is preferably 30%, more preferably 25%, 20%, 15%, and 13% in that order. The lower limit of the W ion content is preferably 0.5%, more preferably 1%, 2%, and 3% in that order. W ions are W 6+ In addition, it includes all W ions with different valences.

[0070] W ions contribute to increasing the refractive index and also have the function of increasing the coloration of the glass, so the content of W ions is preferably within the above range.

[0071] In the glass according to this embodiment, the upper limit of the Bi ion content is preferably 40%, more preferably 35%, 30%, 28%, and 25% in that order. The lower limit of the Bi ion content is preferably 0.5%, more preferably 1%, 2%, and 2.5% in that order. Bi ions are 3+ In addition, it includes all Bi ions with different valences.

[0072] Bi ions contribute to a high refractive index and also have the function of increasing the coloration of the glass, so the content of Bi ions is preferably within the above range.

[0073] In the glass according to this embodiment, the lower limit of the total content of Ti, Nb, and W ions [Ti + Nb + W] is preferably 1%, more preferably 5%, 10%, 15%, 20%, and 23% in that order, and the upper limit of the total content [Ti + Nb + W] is preferably 60%, more preferably 55%, 50%, 45%, 40%, 38%, and 35% in that order.

[0074] In the glass according to this embodiment, the upper limit of the total content of Ti, Nb, W, and Bi ions [Ti + Nb + W + Bi] is preferably 80%, more preferably 75%, 70%, 68%, and 65% in that order. The lower limit of the total content [Ti + Nb + W + Bi] is preferably 1%, more preferably 5%, 10%, 15%, 20%, 23%, and 25% in that order.

[0075] In the glass according to this embodiment, P 5+ , B 3+ and Si 4+ The cation ratio of the total content of Ti ions, Nb ions, W ions and Bi ions to the total content of [(Ti + Nb + W + Bi) / (P 5+ +B 3+ +Si 4+ The lower limit of the cation ratio [(Ti+Nb+W+Bi) / (P 5+ +B 3+ +Si 4+ The upper limit of )] is preferably 4.0, and more preferably 3.5, 3.0, 2.7, and 2.5 in that order.

[0076] In the glass according to this embodiment, Ta 5+ The upper limit of the content of Ta is preferably 5%, and more preferably 3%, 2%, and 1% in that order. 5+ The content may be 0%.

[0077] Ta 5+ has the function of improving the thermal stability of the glass. 5+ If the content of Ta is too high, the refractive index of the glass tends to be low and the melting property tends to be reduced. 5+ The content is preferably in the above range.

[0078] In the glass according to this embodiment, Li + The upper limit of the content of Li is preferably 35%, and more preferably 30%, 27%, 25%, 23%, and 20% in that order.+ The lower limit of the content of Li is preferably 1%, and more preferably 2%, 3%, 5%, and 8% in that order. + The content may be 0%.

[0079] In the glass according to this embodiment, Na + The upper limit of the content of Na is preferably 40%, and more preferably 35%, 30%, 25%, 20%, and 18% in that order. + The lower limit of the Na content is preferably 0.5%, and more preferably 1%, 1.5%, 3%, and 5% in that order. + The content may be 0%.

[0080] The glass is Li + or Na + The inclusion of Li makes it easier to chemically strengthen the glass. + or Na + If the content of Li is too high, the thermal stability of the glass may decrease. + and Na + The content of each of the above is preferably within the above range.

[0081] In the glass according to this embodiment, Li + and Na + The total content of [Li + +Na + The upper limit of the total content [Li + +Na + The lower limit of [%] is preferably 1%, and more preferably 5%, 10%, 15%, and 20% in that order.

[0082] In the glass according to this embodiment, K + The upper limit of the content of K is preferably 20%, and more preferably 15%, 13%, 10%, 8%, 5%, and 3% in that order. + The lower limit of the content of K is preferably 0.1%, and more preferably 0.5%, 1.0%, and 1.2% in that order. +The content may be 0%.

[0083] K + has the function of improving the thermal stability of the glass. + If the content is too high, the thermal stability tends to decrease. + The content is preferably in the above range.

[0084] In the glass according to this embodiment, Rb + The upper limit of the Rb content is preferably 5%, and more preferably 3%, 1%, and 0.5% in that order. + The content may be 0%.

[0085] In the glass according to this embodiment, Cs + The upper limit of the Cs content is preferably 5%, and more preferably 3%, 1%, and 0.5% in that order. + The content may be 0%.

[0086] Rb + and Cs + On the other hand, if the content of these elements is too high, the refractive index nd may decrease and the volatilization of glass components during melting may increase. + and Cs + The content of each of the above is preferably within the above range.

[0087] In the glass according to this embodiment, Mg 2+ The upper limit of the Mg content is preferably 15%, and more preferably 10%, 5%, 3%, and 1% in that order. 2+ The content may be 0%.

[0088] In the glass according to this embodiment, Ca 2+ The upper limit of the Ca content is preferably 15%, and more preferably 10%, 5%, 3%, and 1% in that order. 2+ The content may be 0%.

[0089] In the glass according to this embodiment, Sr 2+ The upper limit of the Sr content is preferably 15%, and more preferably 10%, 5%, 3%, and 1% in that order. 2+ The content may be 0%.

[0090] In the glass according to this embodiment, Ba 2+ The upper limit of the Ba content is preferably 25%, and more preferably 20%, 18%, 15%, 10%, and 5% in that order. 2+ The content may be 0%.

[0091] Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ Each of these glass components functions to improve the thermal stability and meltability of the glass. On the other hand, if the content of these glass components is too high, the high refractive index may be impaired and the thermal stability of the glass may be reduced. Therefore, it is preferable that the content of each of these glass components be within the above-mentioned range.

[0092] In the glass according to this embodiment, Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ The total content of [Mg 2+ +Ca 2+ +Sr 2+ +Ba 2+ The upper limit of [%] is preferably 30%, and more preferably 25%, 20%, 18%, 15%, 10%, and 5% in that order.

[0093] In the glass according to this embodiment, Zn 2+ The upper limit of the content of Zn is preferably 15%, and more preferably 10%, 8%, 5%, 3%, and 1% in that order. 2+ The lower limit of the Zn content is preferably 0.1%, more preferably 0.3%, and even more preferably 0.5%. 2+ The content may be 0%.

[0094] Zn2+ has the function of improving the thermal stability of the glass. 2+ If the content is too high, the melting property may be deteriorated. 2+ The content is preferably in the above range.

[0095] In the glass according to this embodiment, Zr 4+ The upper limit of the Zr content is preferably 5%, and more preferably 3%, 2%, and 1% in that order. 4+ The content may be 0%.

[0096] Zr 4+ has the function of improving the thermal stability of the glass. 4+ If the content of Zr is too high, the thermal stability and meltability of the glass tend to decrease. 4+ The content is preferably in the above range.

[0097] In the glass according to this embodiment, Ga 3+ The upper limit of the Ga content is preferably 3%, more preferably 2%, and further more preferably 1%. 3+ The lower limit of the Ga content is preferably 0%. 3+ The content may be 0%.

[0098] In the glass according to this embodiment, In 3+ The upper limit of the content of In is preferably 3%, more preferably 2%, and further more preferably 1%. 3+ The lower limit of the content of In is preferably 0%. 3+ The content may be 0%.

[0099] In the glass according to this embodiment, Sc 3+ The upper limit of the content of Sc is preferably 3%, more preferably 2%, and further more preferably 1%. 3+ The lower limit of the content of Sc is preferably 0%. 3+ The content may be 0%.

[0100] In the glass according to this embodiment, Hf 4+ The upper limit of the content of Hf is preferably 3%, more preferably 2%, and further more preferably 1%. 4+ The lower limit of the content of Hf is preferably 0%. 4+ The content may be 0%.

[0101] In the glass according to this embodiment, Lu 3+ The upper limit of the content of Lu is preferably 3%, more preferably 2%, and further more preferably 1%. 3+ The lower limit of the content of Lu is preferably 0%. 3+ The content may be 0%.

[0102] In the glass according to this embodiment, Ge 4+ The upper limit of the content of Ge is preferably 3%, more preferably 2%, and further more preferably 1%. 4+ The lower limit of the Ge content is preferably 0%. 4+ The content may be 0%.

[0103] In the glass according to this embodiment, La 3+ The upper limit of the content of La is preferably 5%, more preferably 4%, and further more preferably 3%. 3+ The lower limit of the content of La is preferably 0%. 3+ The content may be 0%.

[0104] In the glass according to this embodiment, Gd 3+ The upper limit of the content of Gd is preferably 5%, more preferably 4%, and even more preferably 3%. 3+ The lower limit of the content of Gd is preferably 0%. 3+ The content may be 0%.

[0105] In the glass according to this embodiment, Y 3+ The upper limit of the content of Y is preferably 5%, more preferably 4%, and even more preferably 3%. 3+ The lower limit of the content of Y is preferably 0%.3+ The content may be 0%.

[0106] In the glass according to this embodiment, Yb 3+ The upper limit of the content of Yb is preferably 3%, more preferably 2%, and further more preferably 1%. 3+ The lower limit of the content of Yb is preferably 0%. 3+ The content may be 0%.

[0107] The cationic components of the glass according to this embodiment are mainly the above-mentioned components, i.e., P 5+ , B 3+ , Si 4+ , Al 3+ , Ti ions, Nb ions, W ions, Bi ions, Ta 5+ , Li + , Na + , K. + , Rb + , Cs + , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Zn 2+ , Zr 4+ , Ga 3+ , In 3+ ,Sc. 3+ , Hf 4+ , Lu 3+ , Ge 4+ , La 3+ , Gd 3+ , Y 3+ and Yb 3+ The total content of the above components is preferably greater than 95%, more preferably greater than 98%, even more preferably greater than 99%, and even more preferably greater than 99.5%.

[0108] The glass according to this embodiment contains F as an anion component. - and O 2- It may contain ingredients other than F. - and O 2- Other anion components include Cl - , Br- , I - However, Cl - , Br - , I - All of these components are prone to volatilization during glass melting. The volatilization of these components causes problems such as fluctuations in the glass properties, a decrease in the homogeneity of the glass, and significant wear on the melting equipment. - The content of Br is preferably less than 5 anion %, more preferably less than 3 anion %, even more preferably less than 1 anion %, particularly preferably less than 0.5 anion %, and even more preferably less than 0.25 anion %. - and I - The total content is preferably less than 5 anion %, more preferably less than 3 anion %, even more preferably less than 1 anion %, particularly preferably less than 0.5 anion %, even more preferably less than 0.1 anion %, and even more preferably 0 anion %.

[0109] The anion % is a molar percentage when the total content of all anion components is taken as 100%.

[0110] The glass according to this embodiment is preferably basically composed of the above components, but may contain other components as long as the effects of this embodiment are not impaired.

[0111] For example, the glass according to this embodiment may further contain an appropriate amount of copper (Cu) as a glass component to impart near-infrared light absorption properties to the glass. In addition, the glass may contain V, Cr, Mn, Fe, Co, Ni, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Ce, and the like. These elements may enhance the coloring of the glass and become a source of fluorescence.

[0112] Furthermore, this embodiment does not exclude the inclusion of unavoidable impurities.

[0113] <Other ingredient composition> Pb, As, Cd, Tl, Be, and Se are all toxic, and therefore the glass of this embodiment preferably does not contain these elements as glass components.

[0114] U, Th, and Ra are all radioactive elements, and therefore the glass of this embodiment preferably does not contain these elements as glass components.

[0115] Sb 3+ , Sn 4+ , and Ce 4+ is a glass component that functions as a fining agent and can be added as an optional component. 3+ is a fining agent with a great fining effect.

[0116] Sb 3+ The content of Sb is converted to Sb2O3 and expressed as a percentage by mass. 3+ , Sn 4+ , and Ce 4+ The content ratio of the cation components other than Sb is converted to oxide as in Sb2O3, and Sb 3+ , Sn 4+ , and Ce 4+ The Sb2O3 content is expressed in mass% when the total content of all cationic components other than SbO3 is 100 mass%. The Sb2O3 content is preferably less than 2 mass%, more preferably less than 1 mass%, even more preferably less than 0.5 mass%, and even more preferably less than 0.2 mass%, less than 0.1 mass%, or less than 0.05 mass%. By keeping the Sb2O3 content within the above range, the clarity of the glass can be improved.

[0117] Sn 4+ and Ce 4+ The content of each element is also expressed as an oxide equivalent. 3+ , Sn 4+ , and Ce 4+ The content ratio of the cation components other than Sb is converted to oxide. 3+ , Sn 4+ , and Ce 4+The SnO2 content and CeO2 content are expressed in mass% when the total content of all cationic components other than SnO2 and CeO2 is 100 mass%. The SnO2 and CeO2 contents are each preferably less than 2 mass%, more preferably less than 1 mass%, even more preferably less than 0.5 mass%, and even more preferably less than 0.1 mass%. The SnO2 and CeO2 contents may be 0 mass%. By setting the SnO2 and CeO2 contents within the above ranges, the clarity of the glass can be improved.

[0118] (Glass manufacturing) The glass according to this embodiment can be obtained by preparing uncolored glass and forming a colored layer thereon. Uncolored glass can be produced according to a known glass manufacturing method. For example, multiple compounds are prepared and thoroughly mixed to form batch raw materials, which are then placed in a melting vessel and melted, refined, and homogenized. A glass melt is then formed and slowly cooled to obtain glass. Alternatively, the batch raw materials are placed in a melting vessel and roughly melted (rough melt). The melt obtained by rough melting is rapidly cooled and crushed to produce cullet. The cullet can then be placed in a melting vessel and heated and remelted (remelted) to form a glass melt. The glass melt can then be further refined and homogenized, shaped, and slowly cooled to obtain glass. Known methods can be used to form and slowly cool the glass melt.

[0119] Furthermore, the glass manufacturing process according to this embodiment may include a step of increasing the water content in the glass melt. Steps for increasing the water content in the glass melt include a step of adding water vapor to the melting atmosphere and a step of bubbling a gas containing water vapor into the melt. Of these, it is preferable to include a step of adding water vapor to the melting atmosphere. By including a step of increasing the water content in the glass melt, the βOH value of the glass can be increased. Increasing the βOH value allows for the production of glass with higher transparency.

[0120] (Formation of colored layer) The colored layer can be formed by forming a metal catalyst film on the glass surface and then heat treating it in a reducing atmosphere.

[0121] The metal constituting the metal catalyst film is preferably a metal that absorbs hydrogen ions in the atmosphere and reduces glass components contained in the glass by exchanging hydrogen ions and electrons. Among glass components, a metal that reduces transition metals is more preferred. Specific examples include Au, Ag, Pt, Ni, and Pt-Pd alloys.

[0122] The method for forming a metal catalyst film on the glass surface is not particularly limited as long as it can be formed so as to adhere closely to the glass surface, and examples thereof include vapor deposition, sputtering, and application of a metal paste.

[0123] The reducing atmosphere may contain a gas having reducing power. An example of a gas having reducing power is hydrogen. Therefore, it is preferable to use a hydrogen-containing gas as the reducing atmosphere, and a forming gas containing hydrogen may also be used. Forming gas is a mixed gas consisting of hydrogen and nitrogen, and typically contains about 3 to 5 volume % of hydrogen.

[0124] The heat treatment is carried out at a temperature 200°C lower than the glass transition temperature (Tg-200) or higher and lower than the softening point. The heat treatment time can be adjusted appropriately depending on the desired degree of coloring, the area of the colored layer, the thickness of the colored layer, etc.

[0125] By heat treatment in a reducing atmosphere, a colored layer is formed from the surface of the glass in contact with the metal catalyst film to the interior.

[0126] After the heat treatment, the metal catalyst film is peeled off from the glass surface by any method, including, but not limited to, polishing or dissolving.

[0127] The mechanism by which the colored layer is formed by the above method is not particularly limited, but is thought to be as follows.

[0128] The color of the colored layer formed in this embodiment is thought to be a reduction color caused by glass components, particularly transition metals. Normally, even when a glass molded body is heat-treated in an atmosphere containing a low concentration of hydrogen, about 3 to 5 volume percent, the glass exhibits almost no reduction color. However, because the metal catalyst film occludes hydrogen ions in the atmosphere, more hydrogen ions are supplied to the portion of the glass in contact with the metal catalyst film than to the portion not in contact with the metal catalyst film, resulting in a faster reduction reaction. Therefore, the portion of the glass in contact with the metal catalyst film is deeply colored. The amount of hydrogen ions absorbed by the metal catalyst film is so large that the hydrogen concentration in the atmosphere decreases due to the occlusion by the metal catalyst film. For this reason, the reduction reaction is less likely to proceed in the portion not in contact with the metal catalyst film.

[0129] The reduction reaction of glass components that causes coloring proceeds in all directions from the area in contact with the metal catalyst film. That is, when observed from the cross section of the glass, the colored layer is formed in the thickness direction from the glass surface in contact with the metal catalyst film, and when observed from the surface of the glass, it is formed radially from the area in contact with the metal catalyst film.

[0130] According to the above method, a colored layer with a darker color can be formed. Therefore, even if the thickness of the colored layer is small, the transmittance can be sufficiently reduced. When the thickness of the colored layer is small, the range of the colored layer formed radially from the portion that was in contact with the metal catalyst film, as observed from the surface of the glass, also becomes small. In other words, according to this embodiment, by adjusting the conditions for forming the colored layer, a colored layer with approximately the same shape as the metal catalyst film can be formed when observed from the surface of the glass.

[0131] Furthermore, in order to obtain a fine colored pattern (a pattern in which each light-transmitting surface and each light-shielding surface of a plurality of light-transmitting surfaces are arranged adjacent to each other and alternately) that can be applied to the optical elements described below, a barrier film that prevents contact with the metal catalyst film may be formed on the glass surface to be the non-colored portion before the metal catalyst film is formed on the glass surface.

[0132] The method for forming the barrier film is not particularly limited, and may be, for example, a method capable of forming a fine pattern, such as lithography, inkjet printing, screen printing, vapor deposition, or sputtering, by which a resin, a thin film, or the like is fixed to the glass surface to be the non-colored portion.

[0133] Alternatively, a method may be used in which a barrier film is adhered to the entire glass surface, and then the barrier film adhered to the glass surface on which the colored layer is to be formed is removed using a laser drawing machine or the like, thereby leaving the barrier film on the glass surface to be the non-colored portion.

[0134] The material constituting the barrier film is preferably a material that inhibits the exchange of hydrogen ions and electrons in a reducing atmosphere.

[0135] When a metal catalyst film is formed over the entire surface of the glass surface to be used as the non-colored portion, the metal catalyst film formed on the non-colored portion does not come into contact with the glass surface due to the presence of the barrier film, and the metal catalyst film comes into contact only with the glass surface on which the colored layer is to be formed. When heat treatment is performed in this state in a reducing atmosphere, the exchange of hydrogen ions and electrons on the glass surface to be used as the non-colored portion is suppressed, and the reduction reaction of the glass components is also suppressed, so the reduction reaction proceeds only on the glass surface on which the colored layer is to be formed, allowing the fine pattern formed in the non-colored portion to be transferred.

[0136] By heat treatment in a reducing atmosphere, a colored layer is formed from the glass surface in contact with the metal catalyst film to the interior. After heat treatment, the metal catalyst film and barrier film are peeled off from the glass surface. The peeling method is not particularly limited, but includes methods such as polishing and dissolving.

[0137] FIG. 5 is a diagram showing an example of a process for forming a colored pattern on an optical element by using a barrier film.

[0138] In FIG. 5A, a substrate glass is prepared.

[0139] In Fig. 5B, multiple barrier films are formed on the upper surface of the substrate glass, in this case five barrier films spaced apart in the left-right direction.

[0140] In Fig. 5C, a metal catalyst film is formed on the upper surface of the substrate glass. The metal catalyst film is formed on the upper surfaces of five barrier films spaced apart in the left-right direction and on the upper surface of the substrate glass on which no barrier film is formed (between the five barrier films).

[0141] 5D, heat treatment is performed in a reducing atmosphere, resulting in the formation of a colored layer extending from the surface to the interior of the substrate glass below the metal catalyst film formed on the upper surface of the substrate glass (between the five barrier films) where no barrier film is formed.

[0142] In Figure 5E, the barrier film and metal catalyst film remaining on the upper surface of the substrate glass are removed. As a result, multiple colored layers are formed, spaced apart in the left-right direction, from the surface to the interior of the substrate glass. The multiple colored layers function as multiple light-shielding surfaces (light-shielding portions). Furthermore, multiple light-transmitting surfaces (light-transmitting portions) are formed between the multiple light-shielding surfaces (light-shielding portions).

[0143] (Manufacturing of optical elements, etc.) An optical element made of the glass according to this embodiment can be obtained by preparing an uncolored optical element and forming a colored layer thereon. Uncolored optical elements can be produced according to known manufacturing methods. For example, molten glass is poured into a mold and formed into a plate to produce a glass material. The obtained glass material is then appropriately cut, ground, and polished to produce cut pieces of a size and shape suitable for press molding. The cut pieces are heated and softened, and press-molded (reheat pressed) using a known method to produce an optical element blank that approximates the shape of the optical element. The optical element blank is annealed, and then ground and polished using a known method to produce an optical element. Alternatively, an optical element can be produced by preparing a glass gob or preform for precision press molding according to a known manufacturing method, and then precision press-molding the heated and softened glass gob or preform using an optical element molding die.

[0144] A colored layer can be formed on the manufactured optical element by the above method. Alternatively, a colored layer may be formed during the manufacturing process of the optical element.

[0145] The optically functional surface of the fabricated optical element may be coated with an anti-reflection film, a total reflection film, or the like depending on the intended use.

[0146] According to this embodiment, an optical element made of the above glass can be provided. Examples of types of optical elements include parallax barriers, zone plates, and glass scales for optical encoders, which will be described later. Examples of types of optical elements include lenses such as spherical lenses and aspherical lenses, prisms, and diffraction gratings. Examples of lens shapes include biconvex lenses, plano-convex lenses, biconcave lenses, plano-concave lenses, convex meniscus lenses, and concave meniscus lenses. Optical elements can be manufactured by a method including a step of processing a glass molded body made of the above glass. Examples of processing include cutting, milling, rough grinding, fine grinding, polishing, precision pressing, and the like.

[0147] (Example) The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to these examples.

[0148] Glass samples having the glass compositions shown in Table 1 were prepared by the following procedure, and various evaluations were carried out.

[0149] [Table 1]

[0150] [Glass manufacturing] Oxides, hydroxides, metaphosphates, carbonates, and nitrates corresponding to the glass constituents were prepared as raw materials. These raw materials were weighed and mixed thoroughly so that the resulting glass compositions would be as shown in Table 1. The resulting raw materials (batch raw materials) were placed in a platinum crucible and heated at 1100–1450°C for 2–3 hours to produce molten glass. The molten glass was stirred to homogenize it and refined, and then cast into a mold preheated to an appropriate temperature. The cast glass was heat-treated near the glass transition temperature (Tg) for approximately 1 hour and then allowed to cool to room temperature in the furnace. The glass was processed into a size of 40 mm long, 10 mm wide, and 1.0 mm thick, and two surfaces measuring 40 mm x 10 mm were precision-polished (optically polished) to obtain a glass sample.

[0151] [Confirmation of glass composition] The content of each glass component in the obtained glass sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and it was confirmed that each composition was as shown in Table 1.

[0152] [Optical property measurement] The refractive index nd, specific gravity, and glass transition temperature Tg of the obtained glass sample were measured, and the results are shown in Table 1.

[0153] (i) Refractive index nd The refractive index nd was measured by the refractive index measurement method of JIS standard JIS B 7071-1.

[0154] (ii) Specific gravity The specific gravity was measured by the Archimedes method.

[0155] (iii) Glass transition temperature Tg The glass transition temperature Tg was measured using a thermomechanical analyzer (TMA4000S) manufactured by MAC Sciences at a temperature rise rate of 4°C / min.

[0156] [Average linear expansion coefficient] The average linear expansion coefficient was measured in accordance with the Japan Optical Glass Industry Association standard JOGIS 08-2003 "Method for measuring thermal expansion of optical glass." The diameter of the rod-shaped sample was 5 mm. The results are shown in Table 1.

[0157] [Acid resistance weight loss rate Da] In accordance with the Japan Optical Glass Industry Association standard JOGIS06-2009, the obtained glass sample was ground into powder glass (particle size 425-600 μm) with a weight equivalent to the specific gravity, placed in a platinum cage, immersed in a quartz glass round-bottom flask containing a 0.01 mol / L aqueous solution of nitric acid, and treated in a boiling water bath for 60 minutes. The weight loss rate (%) before and after treatment was measured. The weight loss rate was evaluated based on a rating scale. The results are shown in Table 1.

[0158] Example 1: Formation of colored layers in samples with different glass compositions (Example 1-1) Of the obtained glass samples, a Pt-Pd film was formed in a pattern on one of the optically polished surfaces of the glass sample having the glass composition No. 1 by sputtering (sputtering current 15 mA, film formation time 900 seconds).

[0159] The glass sample on which the Pt-Pd film was formed was heat-treated at 400°C for 5 hours while supplying forming gas (3% by volume of hydrogen, 97% by volume of nitrogen) as a reducing atmosphere at a flow rate of 0.2 L / min.

[0160] The Pt-Pd film was removed by polishing to obtain a glass sample with a colored layer. The obtained glass sample is shown in Figure 6-1.

[0161] [Transmittance measurement] External transmittance was measured at wavelengths of 300 to 2500 nm. External transmittance is defined as the percentage of transmitted light intensity relative to incident light intensity when light is incident in the thickness direction of the glass sample [transmitted light intensity / incident light intensity x 100]. Note that external transmittance also includes the reflection loss of light rays on the sample surface. The results are shown in Figure 7-1. In the figure, the dashed line represents the transmittance of the area with the colored layer, and the solid line represents the transmittance of the same area before the colored layer was formed.

[0162] [OD measurement] For the area with the colored layer, the incident light intensity I0 and transmitted light intensity I at a wavelength of 1100 nm were measured, and the OD (optical density) was calculated using the following formula. For the same area, the OD before the colored layer was formed was also calculated in the same way. The results are shown in Table 2. OD=-log 10 (I / I0)

[0163] (Example 1-2) A glass sample having a colored layer was obtained in the same manner as in Example 1-1, except that a glass sample having the glass composition of No. 2 was used. The obtained glass sample is shown in Figure 6-2. The transmittance was measured in the same manner as in Example 1-1. The results are shown in Figure 7-2. The OD was measured in the same manner as in Example 1-1. The results are shown in Table 2.

[0164] (Examples 1-3) A glass sample having a colored layer was obtained in the same manner as in Example 1-1, except that a glass sample having the glass composition of No. 3 was heat-treated at 430°C for 9 hours. The transmittance was measured in the same manner as in Example 1-1. The results are shown in Figure 7-3. The OD was measured in the same manner as in Example 1-1. The results are shown in Table 2.

[0165] [Table 2]

[0166] Example 2: Formation of colored layers using metal films (metal catalyst films) with different film thicknesses Example 2-1 On one of the optically polished surfaces of the glass sample having the glass composition No. 3, Pt-Pd films with thicknesses of 28 nm, 256 nm, 288 nm, and 420 nm were formed by adjusting the film formation conditions.

[0167] The glass sample with the Pt-Pd film formed was heat-treated at 400°C for 4 hours while supplying forming gas (3% by volume of hydrogen, 97% by volume of nitrogen) as a reducing atmosphere at a flow rate of 0.2 L / min. The Pt-Pd film was removed by polishing to obtain a glass sample with a colored layer.

[0168] The transmittance of the portion having the colored layer was measured in the same manner as in Example 1-1. The relationship between the thickness of the Pt-Pd film and the transmittance is shown in Figure 8-1. The OD of the portion having the colored layer was measured in the same manner as in Example 1-1. The relationship between the thickness of the Pt-Pd film and the OD is shown in Figure 9.

[0169] (Example 2-2) On one of the optically polished surfaces of the glass sample having the glass composition No. 3, Pt-Pd films with thicknesses of 437 nm, 695 nm, 778 nm, and 892 nm were formed by adjusting the film formation conditions.

[0170] The glass sample with the Pt-Pd film formed was heat-treated at 400°C for 9 hours while supplying forming gas (3% by volume of hydrogen, 97% by volume of nitrogen) as a reducing atmosphere at a flow rate of 0.2 L / min. The Pt-Pd film was removed by polishing to obtain a glass sample with a colored layer.

[0171] The transmittance was measured in the same manner as in Example 2-1. The relationship between the thickness of the Pt-Pd film and the transmittance is shown in Figure 8-2. The OD was measured in the same manner as in Example 2-1. The relationship between the thickness of the Pt-Pd film and the OD is shown in Figure 9.

[0172] From Figures 8-1, 8-2 and 9, it was found that the transmittance and OD of the area having the colored layer depend on the heat treatment time, not on the thickness of the metal film (metal catalyst film).

[0173] Example 3: Formation of colored layers using different types of metal films (metal catalyst films) (Example 3-1) Glass samples with colored layers were obtained in the same manner as in Example 1-1, except that Au films with thicknesses of 15 nm and 300 nm were formed instead of the Pt-Pd film on the optically polished surface of a glass sample having the glass composition of No. 3, and the glass sample was heat-treated for 7 hours at 450° C. The OD of the portion with the colored layer was measured in the same manner as in Example 1-1.

[0174] (Example 3-2) A glass sample having a colored layer was obtained in the same manner as in Example 1-1, except that instead of forming a Pt-Pd film on the optically polished surface of a glass sample having the glass composition of No. 3, an Ag paste was applied and the sample was heat-treated at 430°C for 10 hours. OD was measured in the same manner as in Example 3-1. The results are shown in Table 3.

[0175] [Table 3]

[0176] Example 4: Cross-sectional observation of glass with a colored layer formed Example 4-1 A Pt-Pd film was formed on one of the optically polished surfaces of a glass sample having the glass composition of No. 3. In addition, a portion of the optically polished surface of the same sample was polished using a #1000 abrasive, and a Pt-Pd film was also formed on that portion.

[0177] The glass was heat-treated at 400° C. for 5 hours while supplying forming gas (3% by volume of hydrogen, 97% by volume of nitrogen) at a flow rate of 0.2 L / min. The Pt—Pd film was removed by polishing to obtain a glass sample having a colored layer.

[0178] The thickness of the colored layer was measured. The results are shown in Table 4. Table 4 also shows a micrograph of the cross section of the portion having the colored layer. In the micrograph in Table 4, the right side is the glass, and the black part in the center is the colored layer.

[0179] (Example 4-2) An Au film was formed on one of the optically polished surfaces of a glass sample having the glass composition of No. 3. A glass sample having a colored layer was obtained in the same manner as in Example 4-1, except that the glass sample was heat-treated at 450°C for 7 hours.

[0180] The thickness of the colored layer and a micrograph of the cross section of the portion having the colored layer are shown in Table 4. The OD of the portion having the colored layer was measured in the same manner as in Example 1-1. The results are shown in Table 4.

[0181] (Example 4-3) An Au film was formed on one of the optically polished surfaces of a glass sample having the glass composition of No. 3. A glass sample having a colored layer was obtained in the same manner as in Example 4-2, except that the Au film formation time was longer than in Example 4-2.

[0182] The thickness of the colored layer and a micrograph of the cross section of the portion having the colored layer are shown in Table 4. The OD was measured in the same manner as in Example 4-2. The results are shown in Table 4.

[0183] (Example 4-4) A glass sample having a colored layer was obtained in the same manner as in Example 4-2, except that a Pt-Pd film was formed on both optically polished surfaces of the glass sample having the glass composition of No. 3.

[0184] The thickness of the colored layer and a micrograph of the cross section of the portion having the colored layer are shown in Table 4. The OD was measured in the same manner as in Example 4-2. The results are shown in Table 4.

[0185] [Table 4]

[0186] The surface polished using #1000 abrasive has a rougher surface than the optically polished surface. Table 4 shows that the thickness of the colored layer formed varies depending on the surface roughness of the glass.

[0187] Example 5: Formation of a colored layer having a dot pattern A Pt—Pd film was formed in a dot pattern on the optically polished surface of a glass sample having the glass composition of No. 3. The details are as follows.

[0188] A metal plate with a flatness sufficient to cover the glass surface and a dot-patterned opening was prepared. The metal plate was then placed in close contact with the optically polished surface of the glass sample, and a Pt-Pd film was formed over the openings.

[0189] The metal plate was peeled off, and the glass sample having the Pt-Pd film formed in a dot pattern was heat-treated in the same manner as in Example 1-3 to obtain a glass sample having a colored layer. The obtained glass sample is shown in Figure 10.

[0190] Example 6: Change in transmittance by removing the colored layer A glass sample having a colored layer was obtained in the same manner as in Example 1-3, except that the glass sample having the glass composition of No. 3 was processed to have a thickness of 750 μm.

[0191] The cross section of the colored layer was observed under a microscope, and it was confirmed that the colored layer had a thickness of 110 μm. The OD of the colored layer was also measured in the same manner as in Example 1-1. The results are shown in Table 5.

[0192] The obtained glass sample was polished from the side having the colored layer so that the thickness of the glass sample was 660 μm, and the OD of the same part was measured. The results are shown in Table 5.

[0193] Similarly, the glass samples were polished to thicknesses of 610 μm, 500 μm, and 380 μm, and the OD of the same portions was measured. The change in OD from the OD before polishing (no polishing allowance) was calculated. The OD results are shown in Table 5.

[0194] [Table 5]

[0195] According to Table 5, when the polishing depth of the glass sample exceeds 140 μm, the change in OD becomes small. When the colored layer of a glass sample is removed by polishing, only the uncolored portion (transparent area without color) remains. Therefore, further reduction in thickness by polishing results in almost no change in OD. In other words, based on the results of the change in OD due to polishing, it is estimated that the thickness of the colored layer of the glass sample is greater than 90 μm and less than 140 μm. This is consistent with the thickness of the colored layer (110 μm) based on microscopic observation of the cross section. Note that the increase or decrease in OD within the polishing depth range of 140 to 370 μm is slight and is considered to be due to measurement error.

[0196] <Example of an optical element with a colored layer on the glass body> 1 and 2, the optical element of this embodiment has a glass body 1 and a colored layer 2 located inside the glass body 1 and on an optically functional surface of the optical element. The colored layer 2 is located from the surface to the interior of the glass body 1. Alternatively, the colored layer 2 may be located inside the glass body 1, not on the surface of the glass body 1.

[0197] By selectively forming the colored layer 2 inside the glass body 1 and in the light-blocking portion of the optical element, as shown in Figures 3 (Figures 3-1 and 3-2) and 4, the portions with the colored layer 2 block light and the portions without the colored layer 2 transmit light, thereby achieving the desired optical performance. At this time, the colored layer 2 absorbs light reflected on the inner surface of the portion without the colored layer 2, making it possible to obtain a good optical element with reduced generation of stray light. Furthermore, the colored layer 2 can exert a predetermined optical function in cooperation with layers other than the colored layer (for example, an adjacent light-transmitting layer).

[0198] The thickness of the colored layer 2 from the surface to the interior of the glass body 1 is preferably 1 to 300 μm, more preferably 20 to 200 μm, and even more preferably 30 to 150 μm. By satisfying this condition, the optical element can exhibit good functions, including light-blocking performance. If the thickness is below the lower limit of this condition (if the colored layer 2 is less than 1 μm), the light-blocking performance of the colored layer 2 may be insufficient. If the thickness is above the upper limit of this condition (if the colored layer 2 is more than 300 μm), depending on the location of the optical element where the colored layer is formed, the colored layer protruding toward the interior of the glass may block effective light incident obliquely on the optical element, thereby causing the optical element to function poorly.

[0199] The colored layer 2 preferably has an optical density OD of 2.0 or more at a wavelength of 750 nm, and preferably an optical density OD of 3.0 or more at a wavelength of 750 nm. In the wavelength range from the visible light region to the infrared region, the spectral transmittance of the colored layer 2 tends to increase as the wavelength increases. When expressed in terms of optical density OD, this is synonymous with the optical density OD tending to decrease as the wavelength increases. By satisfying the above conditions, the optical element can exhibit excellent functionality, including light-blocking performance in the visible light region. Below the lower limit of this condition (the optical density OD of the colored layer 2 at a wavelength of 750 nm is less than 2.0), the optical element may exhibit insufficient functionality, including light-blocking performance.

[0200] <Example of applying optical elements to a parallax barrier> The advantages of applying the optical element of this embodiment to a parallax barrier (optical device) will be described with reference to Figures 11 and 12. Figure 11 is a diagram for explaining the technical issues with the parallax barrier of the prior art (for example, Patent Document 1), and Figure 12 is a diagram for explaining the advantages of the parallax barrier of this embodiment.

[0201] An example of an optical element that has a pattern of light-transmitting and light-blocking portions and thus plays the role of a transmission slit is a parallax barrier used in display devices that enable stereoscopic viewing without special glasses such as polarized glasses. A parallax barrier is an optical element that has a large number of striped or other light-blocking portions on a substrate such as glass, and when installed in a display device such as a liquid crystal display, it separates the right-eye image from the left-eye image on the display, allowing the viewer's left eye to view only the left-eye image (left-eye pixels L) and the right eye to view only the right-eye image (right-eye pixels R), thereby enabling stereoscopic viewing.

[0202] Typically, the light-shielding portion of a parallax barrier is formed on a glass substrate using a metal material such as chromium or aluminum, or a black resin material, by vapor deposition, printing, or other techniques. Because the glass substrate is typically processed to have a high degree of smoothness, in the case of a liquid crystal display device, light emitted from the liquid crystal panel and transmitted through the color filter is internally reflected at the portion of the glass substrate facing the light-shielding portion of the parallax barrier. In particular, the inner surface of the glass substrate facing the light-shielding portion of the parallax barrier has a high reflectivity due to a difference in refractive index between the inner surface and the light-shielding material, resulting in significant internal reflection. The internally reflected light may then be further internally reflected at the inner surface of the glass substrate on which the color filter is formed, and some of the light may leak out through a transparent portion through which it should not pass. This phenomenon, known as crosstalk, leads to insufficient separation of parallax images and degraded stereoscopic image quality.

[0203] Patent Document 1 proposes providing a high-quality stereoscopic image by providing a concave-convex portion with light-scattering properties on the surface where a color filter is formed or on a position facing the light-shielding portion of a parallax barrier to suppress crosstalk by scattering the light that enters the corresponding portion and causes crosstalk. In the example shown in FIG. 11, multiple light-shielding portions of the parallax barrier protrude downward from the lower surface of the glass substrate. Multiple concave-convex portions are provided on the upper surfaces of the multiple light-shielding portions (the multiple light-shielding portions correspond to the multiple concave-convex portions). Furthermore, multiple light-transmitting portions are formed in the portions of the lower surface of the glass substrate where the multiple light-shielding portions of the parallax barrier are not formed (between the multiple light-shielding portions). However, even if a concave-convex portion with light-scattering properties is provided in part of the path of light that causes crosstalk, light diffusion still occurs, and some of the diffused light may leak out through the light-transmitting portions that should not pass through (see the dashed-dotted line in FIG. 11), and therefore the crosstalk suppression effect cannot be said to be significant.

[0204] In this embodiment, the above-mentioned problem is regarded as an important technical issue, and the optical element has a parallax barrier, and a plurality of colored layers form a plurality of light-shielding surfaces (light-shielding portions) 20A of the parallax barrier. More specifically, in this embodiment, as shown in Fig. 12, a plurality of colored layers are provided from the surface to the interior of the glass substrate, and these plurality of colored layers form a plurality of light-shielding surfaces 20A of the parallax barrier. This makes it possible to achieve the light-shielding function that is the original purpose of the parallax barrier, as in Patent Document 1. In addition, a plurality of light-transmitting surfaces (light-transmitting portions) 20B are formed between the plurality of light-shielding surfaces (light-shielding portions) 20A.

[0205] Furthermore, since the colored layer (light-shielding surface) of this embodiment has the function of absorbing light, most of the light that is reflected by the transparent surface on the exit surface of the glass substrate, returns to the entrance surface, is reflected by the entrance surface, and reaches the exit surface again, and is absorbed by the colored layer, in addition to the light that directly enters the colored layer from the light source (see the dashed-dotted line in Figure 12). This reduces the amount of light that leaks to the outside, making it possible to effectively suppress crosstalk.

[0206] Furthermore, the colored layer (light-shielding surface, light-shielding portion) of this embodiment has almost no difference in refractive index with the light-transmitting surface (light-transmitting portion). As a result, no light is reflected at the boundary with the light-transmitting surface, and the energy of light incident on the colored layer is absorbed as it travels through the colored layer before reaching the boundary with air, so no stray light is generated.

[0207] Furthermore, when providing an uneven portion having light scattering properties as in Patent Document 1, it takes time and effort to process the unevenness, but this embodiment can eliminate the need for such processing.

[0208] Here, a stripe shape is exemplified as the pattern of the light-shielding surface, but the width of the light-shielding surface and the width of the light-transmitting surface may be set to dimensions suitable for the desired three-dimensional effect (number of viewpoints of the three-dimensional image, viewing angle, etc.) based on known technology, and are not limited to the present embodiment (Figure 12).

[0209] Furthermore, in order to reduce moiré (interference patterns between the light-shielding pattern of the parallax barrier and the black matrix of the liquid crystal panel (a light-shielding member for preventing color mixing at the boundaries between color filter pixels)), the light-shielding pattern is not limited to vertical stripes, and may be inclined at a specific angle based on known technology.Furthermore, it is not limited to a pattern consisting of only straight lines, and may be a pattern in which the light-shielding surfaces are connected in a stepped manner, a pattern in which arcs are connected, or the like, based on known technology.

[0210] <Example of applying an optical element to a zone plate> The advantages of applying the optical element of this embodiment to a zone plate (optical device) will be described with reference to Figures 13 and 14. Figure 13 is a diagram for explaining the technical issues of zone plates in conventional technology (for example, Patent Document 2), and Figure 14 is a diagram for explaining the advantages of the zone plate of this embodiment.

[0211] A zone plate is known as an optical element in which a light-blocking pattern is formed on a transparent substrate (e.g., a glass substrate). A zone plate is an optical element with a concentric pattern in which the spacing between the light-transmitting and light-blocking areas changes regularly depending on the radius from the center. A zone plate is sometimes used as a pattern mask in a system in which a pattern mask is placed in front of an image sensor, the shadow of the pattern mask on the image sensor created by incident light from an object is photographed, and an image of the object is obtained by numerical calculation.

[0212] For example, Patent Document 2 proposes an imaging device that can measure distance by arranging a zone plate as an imaging pattern in front of an imaging element, capturing transmitted light whose light intensity is modulated by the pattern, and calculating a cross-correlation function with a development pattern. In Fig. 13, when capturing an image of an object at a finite distance, a grid pattern is projected through a concentric pattern (pattern mask) made of light-shielding parts as a grid pattern.

[0213] A zone plate used as a photographic pattern is formed by forming a pattern of a metal material such as chromium or aluminum, or a black resin material, on a transparent substrate such as glass by a method such as sputtering, vapor deposition, or printing. In the example shown in Figure 13, a plurality of light-shielding portions protrude upward from the upper surface of the glass substrate as a grid pattern of the zone plate. A plurality of light-transmitting portions are formed between the plurality of light-shielding portions.

[0214] In an imaging device using such a zone plate, if reflected light generated on the inner surface of the glass substrate leaks out, it can cause phenomena such as changing the shadow image of the pattern mask that is supposed to be formed or reducing the contrast, which can have adverse effects such as causing errors in distance measurement. Incident light from an object passes through the light-transmitting portion of the zone plate and is partially reflected by the inner surface of the glass substrate facing the imaging element. The light reflected by the inner surface of the glass substrate facing the imaging element is partially reflected again by the inner surface of the glass substrate on which the lattice pattern is formed, and then passes through the side of the zone plate facing the imaging element, potentially reaching the imaging element (see the dashed-dotted line in Figure 13).

[0215] In this embodiment, the above-mentioned problem is regarded as an important technical issue, and the optical element has a zone plate, and a plurality of colored layers form a plurality of light-shielding surfaces (light-shielding portions) 20C of the zone plate. More specifically, in this embodiment, as shown in FIG. 14, a plurality of colored layers are provided from the surface to the interior of a glass substrate, and these plurality of colored layers form a plurality of light-shielding surfaces 20C of the zone plate. This allows the zone plate to fulfill its original purpose of blocking light, as in Patent Document 2. In addition, a plurality of light-transmitting surfaces (light-transmitting portions) 20D are formed between the plurality of light-shielding surfaces (light-shielding portions) 20C.

[0216] Furthermore, since the colored layer (light-shielding surface) of this embodiment has the function of absorbing light, most of the light that is emitted from the light source and reflected at the exit surface of the glass substrate, returns to the incident surface, is reflected at the incident surface, and reaches the exit surface again. This means that the colored layer absorbs the light, thereby reducing the amount of light that leaks to the outside (see the dashed line in Figure 14).

[0217] Furthermore, the colored layer (light-shielding surface, light-shielding portion) of this embodiment has almost no difference in refractive index with the light-transmitting surface (light-transmitting portion). As a result, no light is reflected at the boundary with the light-transmitting surface, and the energy of light incident on the colored layer is absorbed as it travels through the colored layer before reaching the boundary with air, so no stray light is generated.

[0218] The pattern of the light-shielding surface (light-shielding portion) of the zone plate can be, for example, concentric, but the pattern shape, the width of the light-shielding surface, and the width of the light-transmitting surface may be set to dimensions suitable for the intended image reproduction based on known technology, and are not limited to those of this embodiment (Figure 14).

[0219] <Example of applying optical elements to the glass scale of an optical encoder> The advantages of applying the optical element of this embodiment to the glass scale (code pattern) of an optical encoder (optical device) will be described with reference to Figures 15 and 16. Figure 15 is a diagram for explaining the technical issues with the glass scale of an optical encoder of the prior art (for example, Patent Document 3), and Figure 16 is a diagram for explaining the advantages of the glass scale of the optical encoder of this embodiment.

[0220] Glass scales for optical encoders are known as optical elements in which a light-blocking pattern is formed on a transparent substrate (e.g., a glass substrate). Encoders are devices that detect mechanical position and rotation, and optical encoders are primarily composed of a light-emitting element, a glass scale that blocks or transmits light, and a light-receiving element. Light from the light-emitting element is blocked or transmitted by the glass scale, and the light that has passed through or is reflected by the glass scale is detected by the light-receiving element, allowing position and rotation to be measured. When the glass scale is displaced in the measurement direction, the light-dark pattern created on the light-receiving element moves, and a signal corresponding to the light-dark pattern is output from the light-receiving element.

[0221] Glass scales are optical elements that have numerous light-blocking and light-transmitting sections formed on a substrate such as glass, and are generally disk- or rectangular-shaped. The light-blocking sections of glass scales are formed on the glass substrate using techniques such as etching, vapor deposition, and printing, using metal materials such as chromium or aluminum, or black resin material. In the examples shown in Figures 15A and 15B, multiple light-blocking sections of the glass scale protrude downward from the underside of the glass substrate. Multiple light-transmitting sections are formed between the multiple light-blocking sections.

[0222] In optical encoders using such glass scales, for example, when misalignment of the light source device causes tilted parallel light to be irradiated onto the light-receiving element or glass scale, reflections can occur on the inner surface of the glass substrate of the glass scale and leak out through light-transmitting areas that the light should not pass through (see the dashed-dotted lines in Figures 15A and 15B). Figure 15A illustrates an example of a round-trip reflection path within the glass substrate, and Figure 15B illustrates an example of a two-round-trip reflection path within the glass substrate. When this phenomenon occurs, light unrelated to detection (stray light) enters the light-receiving element, causing noise in the detection signal and reducing the accuracy of position detection.

[0223] Patent Document 3 proposes forming the light-shielding portion with an anti-reflection material such as CrO (chromium oxide) or black paint to prevent light reflected by the light-shielding portion (gradations) of the glass scale from reflecting off a lead frame or the like and becoming stray light. Although such anti-reflection materials have absorption properties and are effective in absorbing part of the incident light, due to the difference in refractive index between the anti-reflection material and the glass substrate of the glass scale, it is not possible to prevent the occurrence of reflected light at the interface between the anti-reflection material and the glass substrate, and it cannot be said that the effect of suppressing stray light is sufficient.

[0224] In this embodiment, the above-mentioned problem is regarded as an important technical issue, and the optical element has a glass scale of an optical encoder, and a plurality of colored layers form a plurality of light-shielding surfaces (light-shielding portions) 20E of the glass scale. More specifically, in this embodiment, as shown in FIGS. 16A and 16B, a plurality of colored layers are provided from the surface to the interior of the glass substrate, and these plurality of colored layers form a plurality of light-shielding surfaces 20E of the glass scale. This allows the glass scale of an optical encoder to fulfill its original purpose of blocking light, as in Patent Document 3. In addition, a plurality of light-transmitting surfaces (light-transmitting portions) 20F are formed between the plurality of light-shielding surfaces (light-shielding portions) 20E.

[0225] Furthermore, since the colored layer of this embodiment has the function of absorbing light, light that directly enters the colored portion on the back surface of the glass substrate is absorbed by the colored layer and can be prevented from entering the light-receiving element (see the dashed line in Figure 16A).Light reflected by the transparent surface on the back surface of the glass substrate is reflected back toward the front surface and then returns to the back surface, but most of the light is absorbed by the colored layer formed on the back surface and can be prevented from entering the light-receiving element (see the dashed line in Figure 16B).

[0226] Furthermore, the colored layer (light-shielding surface, light-shielding portion) of this embodiment has almost no difference in refractive index with the light-transmitting surface (light-transmitting portion). As a result, no light is reflected at the boundary with the light-transmitting surface, and the energy of light incident on the colored layer is absorbed as it travels through the colored layer before reaching the boundary with air, so no stray light is generated.

[0227] Here, the example has been given where the pattern on the light-shielding surface is linear (arranged in a straight line), but the shape and width of the light-shielding surface need only be suitable for functioning as a code pattern and are not limited to those of this embodiment (Fig. 16). Also, the example has been given where the colored layer of this embodiment is formed on the light-shielding surface of a rectangular glass scale, but the shape of the glass scale is not limited to a rectangular shape and may be, for example, a disk-shaped glass scale (disk).

[0228] As described above, the optically functional surface of this embodiment has a plurality of light-transmitting surfaces (light-transmitting portions) 20B, 20D, and 20F, and a plurality of light-shielding surfaces (light-shielding portions) 20A, 20C, and 20E, in which each light-transmitting surface (light-transmitting portion) and each light-shielding surface (light-shielding portion) are alternately arranged adjacent to each other. Furthermore, the colored layer 20 of this embodiment has a plurality of colored layers that constitute the plurality of light-shielding surfaces (light-shielding portions) 20A, 20C, and 20E. When this configuration is satisfied, the optical element and optical device of this embodiment can be applied to any optical element and optical device other than a parallax barrier, a zone plate, and a glass scale for an optical encoder.

[0229] <Examples of optical elements used in other applications> In addition to the examples described above, the optical element of this embodiment can have at least one of a lens, a parallel plate, a cover glass (e.g., a cover glass of an image sensor, etc.), an optical filter (e.g., an IR cut filter, a polarizing filter, an ND filter, etc.), a beam splitter, and a prism. In this case, the colored layer can be located on an optically functional surface of at least one of the lens, the parallel plate, the cover glass, the optical filter, the beam splitter, and the prism. [Industrial Applicability]

[0230] The optical element and optical device of this embodiment can be applied to, for example, a parallax barrier, a zone plate, and a glass scale of an optical encoder. [Explanation of symbols]

[0231] 1 Glass body 2 Colored layer (optical functional surface, light shielding surface, light shielding part) 20A Light-shielding surface (light-shielding part) 20B Translucent surface (transparent part) 20C Light shielding surface (light shielding part) 20D Translucent surface (transparent part) 20E Light-shielding surface (light-shielding part) 20F Translucent surface (transparent part)

Claims

1. 1. An optical element having a glass body, a colored layer located inside the glass body and on an optically functional surface of the optical element; the color of the colored layer is a reduction color caused by a glass component, the colored layer has an optical density OD of 2.0 or more at a wavelength of 750 nm; the colored layer is located from the surface to the interior of the glass body and does not reach the rear surface of the glass body; The thickness of the colored layer from the surface to the inside of the glass body is 1 to 300 μm. An optical element characterized by:

2. the optically functional surface has a plurality of light-transmitting surfaces and a plurality of light-blocking surfaces, each of which is alternately arranged adjacent to the other; The colored layer includes a plurality of colored layers that constitute the plurality of light-shielding surfaces.

2. The optical element according to claim 1.

3. the optical element has a parallax barrier, the plurality of colored layers constitute a plurality of light-shielding surfaces of the parallax barrier.

3. The optical element according to claim 2.

4. the optical element includes a zone plate; the plurality of colored layers constitute a plurality of light-shielding surfaces of the zone plate; 3. The optical element according to claim 2.

5. the optical element includes a glass scale of an optical encoder; the plurality of colored layers constitute a plurality of light-shielding surfaces of the glass scale; 3. The optical element according to claim 2.

6. the optical element includes at least one of a lens, a parallel plate, a cover glass, an optical filter, a beam splitter, and a prism; the colored layer is located on at least one optically functional surface of the lens, the parallel plate, the cover glass, the optical filter, the beam splitter, and the prism; 2. The optical element according to claim 1.

7. An optical device comprising the optical element according to any one of claims 1 to 6.

Images