JP7631722B2 - Optical element and light irradiation device - Google Patents

Description

The present invention relates to an optical element and a light irradiation device.

Optical elements are elements that exhibit various functions through the interaction between light and materials. One example of an optical element for converting the area illuminated by light is a diffractive optical element. A diffractive optical element is sometimes called a Diffractive Optical Element or DOE. The top surface of a DOE has an optical region in which materials with different refractive indices are arranged alternately. When one material is air, the optical region is composed of concaves and convexes caused by the other material. When light is incident on a DOE, an optical path difference occurs between the light incident on the concaves and the light incident on the convex parts, causing the light to diffract. By utilizing the diffraction of light, the area illuminated by light can be converted.

Optical elements such as DOEs are used as light irradiation devices by combining them with light sources, etc. In the light irradiation device, the optical element is held away from the light source by a holder, etc. The optical element and the holder are fixed with an adhesive, etc. When adhesive is applied to the optical element, there is a risk that the adhesive will seep into the optical region, which is composed of irregularities, etc. If the adhesive seeps into the optical region, it may cause a problem in which the optical element loses its function.

Patent Document 1 discloses an optical element that prevents the infiltration of adhesive into a line-and-space grating pattern by forming adhesive reservoir grooves on both ends of the grating pattern. In the optical element described in Patent Document 1, the adhesive reservoir groove consists of a single groove. Patent Document 2 discloses an optical element that prevents the infiltration of adhesive into the lens by providing two or more liquid retaining means on the outer periphery of the lens. In both of the optical elements described in Patent Document 1 and Patent Document 2, the structure for preventing the infiltration of adhesive is formed outside the optical region, such as the grating pattern and the lens.

As the optical element becomes smaller, the alignment margin between the optical region and the light source becomes insufficient in the optical elements described in Patent Documents 1 and 2. If the alignment margin between the optical region and the light source is insufficient, there is a high risk of light leakage from outside the optical region. Therefore, it is desirable for the ratio of the area of the optical region to the area of the top surface of the optical element to be as large as possible.

JP 2002-182025 A JP 2009-251249 A

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an optical element that can suppress the infiltration of adhesive into the optical region and increase the ratio of the area of the optical region to the area of the upper surface of the optical element.

A first invention provides a method for manufacturing a semiconductor device comprising: a substrate; an optical function layer located on at least one surface of the substrate, the optical function layer having an optical region formed of concaves and convexes on a surface opposite to the surface facing the substrate; and an adhesive penetration suppression pattern located in a concave portion of the concaves and convexes and forming a closed curve continuous with a convex portion of the concaves and convexes,
The optical region is an optical element having a frame, an adhesive penetration suppression region which is a region that fills the distance range of greater than 0 μm and less than 150 μm from the frame inward, and a central region which is a region surrounded by the adhesive penetration suppression region, and the closed curve is formed in the adhesive penetration suppression region so as to surround the central region.

The second invention is an optical element comprising an optically functional substrate having an optical region consisting of concaves and convexes on one surface, and an adhesive infiltration suppression pattern located in the concaves of the concaves and convexes and forming a continuous closed curve with the convex parts of the concaves and convexities, the optical region having a frame, an adhesive infiltration suppression region that is a region that fills a distance range from 0 μm to 150 μm from the frame inward, and a central region that is a region surrounded by the adhesive infiltration suppression region, and the closed curve is formed in the adhesive infiltration suppression region so as to surround the central region.

The third invention is an optical element according to the first or second invention, in which the upper surface of the adhesive penetration suppression pattern is at the same height as the upper surface of the unevenness.

The fourth invention is an optical element according to any one of the first to third inventions, in which the closed curve is formed in two or more parts.

The fifth invention is the optical element according to the fourth invention, in which the ratio of the pitch of the two adhesive penetration suppression patterns facing each other in parallel to the wavelength of the incident light is 0.2 or more and 2.0 or less.

The sixth invention is the optical element according to the fourth invention, in which the ratio of the pitch of the two adhesive penetration suppression patterns facing each other in parallel to the wavelength of the incident light is 0.4 or more and 1.4 or less.

The seventh invention is an optical element according to any one of the first to sixth inventions, in which the closed curve has an irregular shape.

The eighth invention is an optical element according to any one of the first to seventh inventions, in which the unevenness has a pattern in which the boundaries between the concave and convex portions include curves when viewed from the optical axis of the incident light.

The ninth invention is an optical element according to any one of the first to eighth inventions, in which the optical region has a function of diffracting incident light.

The tenth invention is an optical element according to any one of the first to ninth inventions, in which the adhesive penetration suppression pattern is made of an ultraviolet curable resin.

The eleventh invention is a light irradiation device equipped with an optical element according to any one of the first to tenth inventions.

As described above, the present invention can provide an optical element that can suppress the infiltration of adhesive into the optical region and increase the ratio of the area of the optical region to the area of the upper surface of the optical element.

FIG. 1 is a diagram showing the configuration of a light irradiation device 1. As shown in FIG. FIG. 2 is a diagram showing the transformation of the light irradiation area by the optical element 10. As shown in FIG. FIG. 3 is a diagram showing the configuration of the optical element 10. As shown in FIG. FIG. 4 is a diagram showing another configuration of the optical element 10. In FIG. FIG. 5 is a cross-sectional view in the z direction of the optical region 5 consisting of n-level concaves and convexes 5A. FIG. 6 is a conceptual diagram showing the configuration of the irregularities 5A in the optical region 5. As shown in FIG. FIG. 7 is a conceptual diagram showing the configuration of the GCA type optical region 5. As shown in FIG. FIG. 8 is a diagram showing the configuration of the adhesive infiltration suppression pattern 6. As shown in FIG. FIG. 9 is a diagram showing the configuration of a closed curve L having a regular shape. FIG. 10 is a diagram showing the configuration of a doubly formed closed curve L. FIG. 11 is a diagram showing the pitch P of two adhesive infiltration suppression patterns 6 that face each other in parallel. FIG. 12 is a diagram showing a method for producing the optical element 10 by the imprint method. FIG. 13 is a diagram showing a method for producing the optical element 10 by etching. FIG. 14 is a diagram showing observed images of the optical region 5 and the adhesive infiltration suppression pattern 6. As shown in FIG.

Below, the embodiments of the present invention will be described with reference to the drawings. Note that in the drawings attached to this specification, the scale and dimensional ratios have been appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and ease of understanding.

In addition, terms used in this specification that specify shapes, geometric conditions, and the degree of those conditions, such as "parallel," "orthogonal," and "same," as well as values of lengths and angles, are not to be construed as being strictly binding, but are to be interpreted to include the extent to which similar functions can be expected.

The light irradiation device 1 is a device that irradiates light whose irradiation area has been transformed. FIG. 1 is a diagram showing the configuration of the light irradiation device 1. As shown in FIG. 1, a three-dimensional coordinate system consisting of an x-axis, a y-axis, and a z-axis is defined. The x-axis, the y-axis, and the z-axis are perpendicular to each other. FIG. 1(a) is a top view of the light irradiation device 1. FIG. 1(b) is a bottom view of the light irradiation device 1. FIG. 1(c) is a side view of the light irradiation device 1. FIG. 1(d) is a cross-sectional view of the light irradiation device 1 cut at the position of the arrow A-A' in FIG. 1(a). As shown in FIG. 1, the light irradiation device 1 includes a holder 2, a light source 3, an adhesive 4, and an optical element 10.

The holder 2 is a member for holding the optical element 10 away from the light source 3. The holder 2 is not particularly limited, and may have a shape as shown in FIG. 1, for example. The dimensions of the holder 2 may be, for example, 4×4 mm for the outer dimensions of the top and bottom, 3×3 mm for the opening of the top, 2×2 mm for the opening of the bottom, and 2×4 mm for the outer dimensions of the sides. The material constituting the holder 2 may be, for example, acrylic or epoxy resin, glass, metal, etc.

The light source 3 is a device that emits light. The light source 3 is not particularly limited, but may be, for example, a vertical cavity surface emitting laser. A vertical cavity surface emitting laser is sometimes called a Vertical Cavity Surface Emitting Laser or VCSEL. A VCSEL has small changes in characteristics with temperature changes, so it can emit stable light. For example, near-infrared light with a peak wavelength of 850 nm or 940 nm may be used as the light from the light source 3. Near-infrared light is invisible to the human eye, so it does not interfere with the human field of vision. In addition, near-infrared light is not easily affected by external light in the environment in which it is used indoors.

The adhesive 4 is a member that fixes the optical element 10 to the holder 2. For example, the adhesive 4 is applied to the interface between the optical element 10 and the holder 2 to bond them together. There is no particular limitation on the adhesive 4, but for example, an ultraviolet-curing adhesive, a heat-curing adhesive, etc. can be used. By using an ultraviolet-curing adhesive, a heat-curing adhesive, etc. as the adhesive 4, sufficient adhesive strength can be exerted to ensure stable functioning of the light irradiation device 1.

The optical element 10 is an element that exhibits various functions through the interaction between light and matter. FIG. 2 is a diagram showing the transformation of the light irradiation area by the optical element 10. The pre-transformation irradiation area S1 and the post-transformation irradiation area S2 shown in FIG. 2 are merely examples. The pre-transformation irradiation area S1 is, for example, a circle. The irradiation area of the light 30 is transformed as the light 30 passes through the optical area 5. The post-transformation irradiation area S2 can be, for example, nine circles on the screen 7. The light irradiation area can be freely controlled by performing optical design for the optical area 5.

The configuration of the optical element 10 will be described. FIG. 3 is a diagram showing the configuration of the optical element 10. FIG. 3(a) is a perspective view of the optical element 10. FIG. 3(b) is a cross-sectional view of the optical element 10 cut at the position of the arrow B-B' in FIG. 3(a). As shown in FIG. 3(b), the optical element 10 includes a substrate 11, an optical functional layer 12, and an adhesive penetration suppression pattern 6.

The substrate 11 is a member for supporting the optical function layer 12. The substrate 11 may be optically transparent. For example, quartz glass, soda glass, calcium fluoride, magnesium fluoride, barium borosilicate glass, amino borosilicate glass, polycarbonate, polyethylene terephthalate, methyl methacrylate butadiene styrene copolymer, methyl methacrylate styrene copolymer, acrylic styrene copolymer, acrylonitrile butadiene styrene copolymer, etc. may be used as the substrate 11.

When used as a reflective optical element, the substrate 11 does not necessarily need to be light-transmitting.

The shape of the substrate 11 is not particularly limited, but may be, for example, a rectangular parallelepiped. The dimensions of the substrate 11 may be, for example, 3 mm x 3 mm x 0.5 mm. The ends of the substrate 11 may be chamfered. By chamfering the ends of the substrate 11, damage to the ends of the substrate 11 can be suppressed when the substrate 11 is transported, etc.

The optical functional layer 12 is a layer for forming the optical region 5. The optical functional layer 12 is located on at least one surface of the substrate. The thickness of the optical functional layer 12 may be, for example, 20 μm. The optical functional layer 12 may be formed, for example, by a spin coating method.

The optical functional layer 12 is not particularly limited, but may be, for example, an ultraviolet-curable resin. The ultraviolet-curable resin may be, for example, a resin whose main material is urethane acrylate, polyester acrylate, epoxy acrylate, polyether acrylate, polythiol, butadiene acrylate, or the like. By forming the optical functional layer 12 from an ultraviolet-curable resin, the optical region 5 can be easily formed by an imprinting method or the like.

The optical function layer 12 may be formed, for example, from a thermosetting resin or an electron beam curable resin. The optical function layer 12 may also be formed from a thermosetting or ultraviolet curable spin-on glass.

An adhesion layer may be formed between the substrate 11 and the optical functional layer 12. For example, a silane coupling agent or the like may be used as the adhesion layer. By forming the adhesion layer, the adhesion between the substrate 11 and the optical functional layer 12 can be improved. By improving the adhesion, it is possible to prevent the substrate 11 and the optical functional layer 12 from peeling off when the mold 8 is released from the optical functional layer 12 in the imprint method. Furthermore, when used as an optical element for a long period of time, the improved adhesion is often advantageous.

The substrate 11 and the optically functional layer 12 may be combined into one layer as the optically functional substrate 13. FIG. 4 is a diagram showing another configuration of the optical element 10. FIG. 4(a) is a perspective view of the optical element 10. FIG. 4(b) is a cross-sectional view of the optical element 10 cut at the position of the arrow C-C' in FIG. 4(a). As shown in FIG. 4(b), the optical element 10 comprises an optically functional substrate 13 and an adhesive infiltration suppression pattern 6.

The optical function substrate 13 is a member for forming the optical region 5. The optical function substrate 13 is a member that can independently maintain its shape. The optical function substrate 13 may have optical transparency. As the optical function substrate 13, for example, quartz glass, soda glass, calcium fluoride, magnesium fluoride, barium borosilicate glass, amino borosilicate glass, polycarbonate, polyethylene terephthalate, methyl methacrylate butadiene styrene copolymer, methyl methacrylate styrene copolymer, acrylic styrene copolymer, acrylonitrile butadiene styrene copolymer, etc. may be used. The optical function substrate 13 can be formed with the optical region 5 by, for example, an etching method, an injection molding method, etc.

When used as a reflective optical element, the optically functional substrate 13 does not necessarily need to be optically transparent.

The shape of the optically functional substrate 13 is not particularly limited, but may be, for example, a rectangular parallelepiped. The dimensions of the optically functional substrate 13 may be, for example, 3 mm x 3 mm x 0.5 mm. The ends of the optically functional substrate 13 may be chamfered. By chamfering the ends of the optically functional substrate 13, damage to the ends of the optically functional substrate 13 can be suppressed when the optically functional substrate 13 is transported, etc.

The optical function layer 12 has an optical region 5 consisting of irregularities 5A on the side facing the substrate 11 and the opposite side. In the case of the optical function substrate 13, an optical region 5 consisting of irregularities 5A is provided on one side. The optical region 5 is a region that exhibits an optical function in response to incident light. The optical function may be a function due to the diffraction or refraction of light, etc.

As shown in FIG. 3(a) and FIG. 4(a), the optical region 5 has a frame 50, an adhesive infiltration suppression region 51, and a central region 52. The frame 50 is a line that forms the outer shape of the optical region 5. The shape of the frame 50 is not particularly limited, but may be, for example, a square or a circle.

The adhesive infiltration suppression region 51 is a region in which the adhesive infiltration suppression pattern 6 is formed. The adhesive infiltration suppression region 51 is a region that fills the range of distances from the frame 50 toward the inside to greater than 0 μm and less than 150 μm. By setting the adhesive infiltration suppression region 51 to a range of distances greater than 0 μm, the adhesive infiltration suppression pattern 6 can be formed near the frame 50. Furthermore, by setting the adhesive infiltration suppression region 51 to a range of distances less than 150 μm, a sufficient range can be secured for providing the adhesive infiltration suppression pattern 6 described later. Furthermore, even when considering alignment errors in the xy directions between the light source 3 and the optical region 5, light leakage from outside the optical region can be sufficiently suppressed. The shape of the adhesive infiltration suppression region 51 is determined by the shape of the frame 50.

The central region 52 is an area in which the adhesive infiltration suppression pattern 6 is not formed. The central region 52 is an area surrounded by the adhesive infiltration suppression region 51. The shape of the central region 52 is determined by the shapes of the frame 50 and the adhesive infiltration suppression region 51.

As shown in Figures 3(b) and 4(b), the optical region 5 is composed of irregularities 5A in a cross section in the z-axis direction. The irregularities 5A have recesses 5B and protrusions 5C. The recesses 5B are portions occupied by air. The protrusions 5C are portions occupied by the material that constitutes the optical function layer 12 or the optical function substrate 13. The recesses 5B and the protrusions 5C are composed of substances with different refractive indices. An optical path difference occurs between the light incident on the recesses 5B and the light incident on the protrusions 5C, and thus the optical function can be realized.

The unevenness 5A is not limited to the two-level example shown in FIG. 3(b) and FIG. 4(b), but may be three or more levels. FIG. 5 is a cross-sectional view in the z direction of an optical region 5 consisting of n levels of unevenness 5A. In FIG. 5, the adhesive infiltration suppression pattern 6 is omitted. n is a natural number of 2 or more. n levels means that the maximum number of steps of the unevenness 5A is n. As shown in FIG. 8, unevenness 5A with a number of steps less than n may be present. The larger the value of n, the more accurately the light irradiation region can be controlled.

The unevenness 5A may have a pattern in which the boundary between the recessed portion 5B and the protruding portion 5C includes a curve when viewed from the optical axis of the incident light. FIG. 6 is a conceptual diagram showing the configuration of the unevenness 5A in the optical region 5. In FIG. 6, the adhesive infiltration suppression pattern 6 is omitted. The optical axis of the incident light is the z-axis in FIG. 6. The boundary between the recessed portion 5B and the protruding portion 5C is the interface between the air that constitutes the recessed portion 5B and the material that constitutes the protruding portion 5C. The curve may be, for example, a wavy line, a broken line, or a combination of these. By including a curve in the boundary between the recessed portion 5B and the protruding portion 5C, the light irradiation region can be controlled more accurately.

The optical region 5 may be a pattern in which unit cells 53 consisting of the same irregularities 5A are arranged. A pattern in which unit cells 53 are arranged is called a grating cell array type. The grating cell array type is also called a Grating Cell Array type or a GCA type. FIG. 7 is a conceptual diagram showing the configuration of a GCA type optical region 5. FIG. 7 shows an example of a GCA type optical region 5 in which nine unit cells 53 are arranged. The GCA type optical region 5 may be arranged in a different direction for each unit cell 53. By using a GCA type optical region 5, the light irradiation region can be controlled more accurately.

The width of the recesses 5B and the protrusions 5C on the upper surface of the irregularity 5A may be, for example, 0.1 μm or more and 20 μm or less. The depth of the recesses 5B, i.e., the height of the protrusions 5C, may be, for example, 0.1 μm or more and 3 μm or less. The pitch of the irregularities 5A may be, for example, 0.2 μm or more and 40 μm or less.

The adhesive infiltration suppression pattern 6 is a pattern that has the function of blocking the adhesive 4. Figure 8 is a diagram showing the configuration of the adhesive infiltration suppression pattern 6. The adhesive infiltration suppression pattern 6 is located in the recess 5B, and forms a closed curve L that is continuous with the protrusion 5C. A closed curve is a curve whose starting point and end point coincide. Continuous means that one is connected to the next. As shown in Figure 8, when the adhesive infiltration suppression pattern 6 and the protrusion 5C that is continuous with the adhesive infiltration suppression pattern 6 are connected together, a closed curve L is formed.

Figure 8 (a) is a diagram showing the optical region 5 and the adhesive infiltration suppression pattern 6. By positioning the adhesive infiltration suppression pattern 6 in the recess 5B, it is not necessary to form the adhesive infiltration suppression pattern 6 outside the optical region 5, so that the ratio of the area of the optical region 5 to the area of the upper surface of the optical element 10 can be increased. Furthermore, by positioning the adhesive infiltration suppression pattern 6 in the recess 5B, the outline of the convex portion 5C can be partially left, and the loss of the optical function of the optical region 5 can be suppressed. And, by forming a closed curve L continuous with the convex portion 5C, the adhesive infiltration suppression pattern 6 can suppress the infiltration of the adhesive 4 into the optical region 5. Therefore, the loss of the optical function of the optical region 5 can be suppressed.

The closed curve L is formed in the adhesive infiltration suppression region 51 so as to surround the central region 52. FIG. 8(b) is a diagram in which only the portion forming the closed curve L is extracted from FIG. 8(a) and the adhesive infiltration suppression region 51 and the central region 52 are superimposed. By forming the closed curve L in the adhesive infiltration suppression region 51 so as to surround the central region 52, the adhesive infiltration suppression pattern 6 can be formed in the vicinity of the frame 50. Therefore, it is possible to prevent incident light from being irradiated onto the adhesive infiltration suppression pattern 6.

The width of the adhesive infiltration suppression pattern 6 may be, for example, 0.1 μm or more and 20 μm or less. The height of the adhesive infiltration suppression pattern 6 may be, for example, 0.1 μm or more and 3 μm or less. The upper surface of the adhesive infiltration suppression pattern 6 may be at the same height as the upper surface of the unevenness 5A. By having the upper surface of the adhesive infiltration suppression pattern 6 and the upper surface of the unevenness 5A at the same height, the infiltration of the adhesive 4 into the optical region 5 can be more reliably suppressed.

The closed curve L may have an irregular shape. Irregular means that the shape is not a regular shape such as a rectangle or a circle. In the example shown in FIG. 8(a), the closed curve L has an irregular shape. Since the closed curve L has an irregular shape, the diffraction direction of the light irradiated to each adhesive infiltration suppression pattern 6 becomes irregular, so that the adhesive infiltration suppression pattern 6 can be made invisible. Therefore, it is possible to prevent the position of the adhesive infiltration suppression pattern 6 from being identified.

The closed curve L may be a regular shape such as a rectangle or a circle. Figure 9 is a diagram showing the configuration of a regular shaped closed curve L. Figure 9(a) is a diagram showing the configuration of a rectangular closed curve L. Figure 9(b) is a diagram showing the configuration of a circular closed curve L. The regular shape of the closed curve L simplifies the design of the adhesive infiltration suppression pattern 6. Therefore, the design time of the adhesive infiltration suppression pattern 6 can be shortened.

The closed curve L may be formed in two or more layers. FIG. 10 is a diagram showing the configuration of a closed curve L formed in two layers. FIG. 10(a) is a diagram showing the configuration of a closed curve L formed in two layers and having an irregular shape. FIG. 10(b) is a diagram showing the configuration of a closed curve L formed in two layers and having a regular shape. By forming the closed curve L in two or more layers, it is possible to more reliably suppress the infiltration of the adhesive 4 into the optical region 5.

Figure 11 is a diagram showing the pitch P of two adhesive infiltration suppression patterns 6 that face each other in parallel. The pitch P is the distance between corresponding sides of two adhesive infiltration suppression patterns 6 that face each other in parallel when the closed curve L is formed in two or more places.

According to the principle of diffraction, the following equation (1) holds between the pitch P, the wavelength λ of the incident light, and the diffraction angle θ of the light.

Furthermore, when the phase difference between the pattern portion and the air portion at the air interface of a two-level optical element is 180°, the following formula (2) is established.

however,
P: pitch, λ: wavelength of incident light, θ: diffraction angle of light, h: pattern height, and n: refractive index of the pattern material.

It is widely known that it is difficult for diffractive optical elements to control zero-order light, that is, light that has the same shape and is on the same axis as the light before conversion. It is also widely known that when the phase difference between the pattern portion and the air portion is 180°, the intensity of the zero-order light is at a minimum, and that it becomes easier to control the intensity of the zero-order light when the phase difference is close to 180°.

For example, when the phase difference is set to 180° in a pattern material with a refractive index of 1.5, the wavelength λ of the incident light and the pattern height h are equal according to formula (2). However, in a diffractive optical element in which the intensity of the zeroth-order light is controlled to a constant level or the pattern material is not 1.5, the relationship between λ and h may change, so the present invention does not need to be limited to λ=h. The ratio P/λ may be 0.2 or more and 2.0 or less, preferably 0.4 or more and 1.4 or less, and more preferably 0.4 or more and less than 1.0. The reason for this will be explained below.

The aspect ratio of the adhesive infiltration suppression pattern 6 is preferably 10 or less. For example, if the width of the adhesive infiltration suppression pattern 6 is d, the height of the adhesive infiltration suppression pattern 6 is preferably 10d or less. The wavelength λ of the incident light is preferably equal to the height of the adhesive infiltration suppression pattern 6, and is therefore 10d or less. The pitch P is preferably twice the width of the adhesive infiltration suppression pattern 6, and is therefore 2d. In other words, in order for the aspect ratio of the adhesive infiltration suppression pattern 6 to be 10 or less, the ratio P/λ needs to be 0.2 or more. By setting the ratio P/λ to 0.2 or more, the aspect ratio of the adhesive infiltration suppression pattern 6 is 10 or less, and therefore the collapse of the adhesive infiltration suppression pattern 6 can be suppressed.

It is more preferable that the aspect ratio of the adhesive infiltration suppression pattern 6 is 5.0 or less. For example, if the width of the adhesive infiltration suppression pattern 6 is d, the height of the adhesive infiltration suppression pattern 6 is preferably 5.0d or less. The wavelength λ of the incident light is preferably equal to the height of the adhesive infiltration suppression pattern 6, and is therefore 5.0d or less. The pitch P is preferably twice the width of the adhesive infiltration suppression pattern 6, and is therefore 2d. In other words, in order to make the aspect ratio of the adhesive infiltration suppression pattern 6 5.0 or less, the ratio P/λ needs to be 0.4 or more. By making the ratio P/λ 0.4 or more, the aspect ratio of the adhesive infiltration suppression pattern 6 is 5.0 or less, and therefore the collapse of the adhesive infiltration suppression pattern 6 can be more reliably suppressed.

The diffraction angle θ of light by the adhesive infiltration suppression pattern 6 is preferably 30° or more. In other words, sin θ is preferably 0.5 or more. From formula (1), the ratio P/λ is preferably 2.0 or less. By setting the ratio P/λ to 2.0 or less, the diffraction angle θ of light can be set to 30° or more. For example, when the effective illumination area provided by the optical area 5 is ±30°, which is about the angle of view of a typical camera, the diffracted light that becomes noise caused by the adhesive infiltration suppression pattern 6 can be made to escape outside the effective illumination area.

It is more preferable that the diffraction angle θ of light by the adhesive infiltration suppression pattern 6 is 45° or more. In other words, it is preferable that sin θ is 1/√2 or more. From formula (1), it is preferable that the ratio P/λ is 1.4 or less. By setting the ratio P/λ to 1.4 or less, the diffraction angle θ of light can be made 45° or more. For example, when the effective irradiation area provided by the optical area 5 is ±30°, which is about the angle of view of a typical camera, the diffracted light that becomes noise caused by the adhesive infiltration suppression pattern 6 can be more reliably guided outside the effective irradiation area.

It is even more preferable that the adhesive infiltration suppression pattern 6 does not diffract light. sinθ is a value between 0 and 1.0. In formula (1), when sinθ is greater than 1, that is, when the ratio P/λ is less than 1.0, light is not diffracted. Therefore, even if incident light is irradiated onto the adhesive infiltration suppression pattern 6, the diffraction of light can be suppressed. Therefore, by making the ratio P/λ less than 1.0, the diffracted light that can become noise caused by the adhesive infiltration suppression pattern 6 can be suppressed.

From the above, the ratio P/λ may be 0.2 or more and 2.0 or less, preferably 0.4 or more and 1.4 or less, and more preferably 0.4 or more and less than 1.0.

The adhesive penetration suppression pattern 6 may be made of an ultraviolet-curable resin, as with the optical functional layer 12. By making the adhesive penetration suppression pattern 6 out of an ultraviolet-curable resin, the unevenness 5A and the adhesive penetration suppression pattern 6 can be formed simultaneously. This allows the time required to produce the optical element 10 to be shortened.

The optical region 5 and the adhesive infiltration suppression pattern 6 may be formed by an imprinting method. FIG. 12 is a diagram showing a method for producing an optical element 10 by an imprinting method. As shown in FIG. 12(a), a substrate 11 is prepared. As shown in FIG. 12(b), an uncured optical functional layer 12 is formed by applying an ultraviolet curable resin onto one surface of the substrate 11. As shown in FIG. 12(c), the uneven surface of the mold 8 is pressed against the surface of the optical functional layer 12 opposite to the side facing the substrate 11. The uneven surface of the mold 8 has a pattern that is an inversion of the unevenness 5A and the adhesive infiltration suppression pattern 6. As shown in FIG. 12(d), the optical functional layer 12 is cured by irradiating the optical functional layer 12 with ultraviolet rays UV from the back side of the mold 8. As shown in FIG. 12(e), the mold 8 is released from the optical functional layer 12, whereby the optical region 5 and the adhesive infiltration suppression pattern 6 are formed in the optical functional layer 12. The optical element 10 is completed by a series of steps shown in FIG. 12.

The mold 8 is preferably made of a material that transmits ultraviolet (UV) light. A master mold made of quartz glass or the like may be used as the mold 8. A resin replica mold replicated from the master mold may also be used as the mold 8.

The optical region 5 and adhesive penetration suppression pattern 6 are not limited to being formed by the imprint method, but may be formed by, for example, a lithography method such as photolithography or electron beam lithography.

In the optical element 10 shown in FIG. 12(e), the substrate 11 may be etched using the optical functional layer 12 as a mask. Since the optical region 5 and the adhesive penetration suppression pattern 6 are formed in the substrate 11, it is possible to obtain an optical element 10 in which the substrate 11 serves as an optically functional substrate 13.

Figure 13 is a diagram showing a method of manufacturing an optical element 10 by etching. Figure 13 (a) is a diagram showing the optical element 10 shown in Figure 12 (e) in which the substrate 11 is replaced with an optical functional substrate 13. As shown in Figure 13 (b), the optical functional layer 12 and the optical functional substrate 13 are anisotropically etched using an etching gas. Argon or the like may be used as the etching gas. By using argon as the etching gas, it is possible to suppress the etching gas from chemically reacting with the optical functional layer 12 and the optical functional substrate 13. As shown in Figure 13 (c), the optical element 10 is completed by removing the remaining film of the optical functional layer 12. When the optical functional layer 12 is an ultraviolet curable resin, the remaining film of the optical functional layer 12 may be removed by reactive ion etching using oxygen plasma or the like. When the optical functional substrate 13 is quartz glass, the optical functional substrate 13 is not etched by reactive ion etching using oxygen plasma, so only the remaining film of the optical functional layer 12 can be removed.

A hard mask may be formed between the optical functional layer 12 and the optical functional substrate 13. A metal such as chromium may be used as the hard mask. By forming a hard mask between the optical functional layer 12 and the optical functional substrate 13, the line edge roughness of the optical region 5 and the adhesive penetration suppression pattern 6 can be reduced.

The following examples will further explain the present invention.

A pattern was designed consisting of an optical region and an adhesive infiltration suppression pattern. In the optical region, the width of the concave portion was 1 μm, the width of the convex portion was 1 μm, and the height of the convex portion was 1 μm. In the adhesive infiltration suppression pattern, the width was 300 nm and the pitch was 600 nm.

The mold pattern was designed by inverting the designed pattern. The mold pattern was formed on a quartz substrate using lithography. The quartz substrate on which the mold pattern was formed was used as the mold.

A glass substrate with a thickness of 0.5 mm was prepared. Uncured UV-curable resin was applied to the glass substrate in a film thickness of 20 μm. A mold was pressed onto the UV-curable resin. The UV-curable resin was cured by irradiating it with UV rays through the mold. The mold was released from the UV-curable resin to form an optical region and an adhesive penetration suppression pattern in the UV-curable resin, producing an optical element.

The conductivity was improved by sputtering platinum-palladium to a thickness of 2 nm onto the UV-curable resin on which the optical region and adhesive penetration suppression pattern were formed. The optical region and adhesive penetration suppression pattern were observed using a scanning electron microscope. A scanning electron microscope is also called a Scanning Electron Microscope or SEM. The conditions for observation using the SEM were an acceleration voltage of 5 kV, a numerical aperture of 30 μm, and a working distance of 3 mm.

Figure 14 shows an observation image of the optical region and the adhesive infiltration suppression pattern. From Figure 14, it was confirmed that the adhesive infiltration suppression pattern was located in the recess. This enabled the ratio of the area of the optical region to the area of the top surface of the optical element to be increased.

The optical element of the present invention can be used, for example, in light irradiation devices for three-dimensional face authentication to enhance security in electronic devices such as smartphones.

1 Light irradiation device 10 Optical element 11 Substrate 12 Optical functional layer 13 Optical functional substrate 2 Holder 3 Light source 4 Adhesive 5 Optical region 50 Frame 51 Adhesive infiltration suppression region 52 Central region 53 Unit cell 5A Concave/convex 5B Concave 5C Convex 6 Adhesive infiltration suppression pattern 7 Screen 8 Mold 8A Pattern surface 8B Back surface S1 Pre-conversion irradiation region S2 Post-conversion irradiation region L Closed curve P Pitch UV Ultraviolet light

Claims (11)

A substrate;
An optical functional layer located on at least one surface of the substrate, the optical functional layer having an optical region having projections and recesses on a surface opposite to the surface facing the substrate;
an adhesive infiltration suppression pattern that is located in a concave portion of the concave portion and forms a continuous closed curve with the convex portion of the concave portion,
The optical region has a frame, an adhesive infiltration suppression region that is a region that satisfies a distance range of more than 0 μm and less than 150 μm from the frame toward the inside, and a central region that is a region surrounded by the adhesive infiltration suppression region,
The closed curve is formed in the adhesive penetration suppression region so as to surround the central region.
Optical elements. An optically functional substrate having an optical region formed of projections and recesses on one surface thereof;
an adhesive infiltration suppression pattern that is located in a concave portion of the concave portion and forms a continuous closed curve with the convex portion of the concave portion,
The optical region has a frame, an adhesive infiltration suppression region that is a region that satisfies a distance range of more than 0 μm and less than 150 μm from the frame toward the inside, and a central region that is a region surrounded by the adhesive infiltration suppression region,
The closed curve is formed in the adhesive penetration suppression region so as to surround the central region.
Optical elements. The upper surface of the adhesive penetration suppression pattern is at the same height as the upper surface of the unevenness.
The optical element according to claim 1 . The closed curve is formed in two or more parts.
The optical element according to claim 1 . 5. The optical element according to claim 4,
a ratio of the pitch of the two adhesive infiltration suppression patterns facing each other in parallel to the wavelength of incident light is 0.2 or more and 2.0 or less;
Optical elements. 5. The optical element according to claim 4,
a ratio of the pitch of the two adhesive infiltration suppression patterns facing each other in parallel to the wavelength of incident light is 0.4 or more and 1.4 or less;
Optical elements. The closed curve is an irregular shape.
The optical element according to claim 1 . The unevenness has a pattern in which the boundaries between the concave portions and the convex portions include curved lines when viewed from the optical axis of the incident light.
The optical element according to claim 1 . The optical region has a function of diffracting incident light.
9. The optical element according to claim 1. The adhesive penetration suppression pattern is made of an ultraviolet curable resin.
10. The optical element according to claim 1 . An optical element comprising the optical element according to any one of claims 1 to 10.
Light irradiation device.