Optical element, optical system device, and optical system device manufacturing method

Abstract

The purpose of the present invention is to provide: an optical element that can be easily packaged with other structural components; an optical system device using the optical element; and an optical element device manufacturing method.　Provided is an optical element having an uneven structure 20 which demonstrates an optical function and which is provided on a boundary surface 11 between a first medium layer 1 having a first refractive index and a second medium layer 2 having a second refractive index higher than the first refractive index. The optical element is characterized by having formed therein adjustment sections 7 that are for creating distance from the uneven structure 20 towards the first medium layer so that the distance is constant with respect to the uneven structure 20.

Description

Optical element, optical system device, and method of manufacturing optical system device

[0001] The present invention relates to an optical element, an optical system device, and a method for manufacturing an optical system device.

[0002] Three-dimensional measurement sensors using the time-of-flight (TOF) method are being adopted in mobile devices, cars, robots, etc. This method measures the distance to an object from the time it takes for light from a light source to be irradiated onto the object, reflected, and returned. If the light from the light source is irradiated uniformly over a specified area of ​​the object, the distance at each irradiated point can be measured, and the three-dimensional structure of the object can be detected.

[0003] The sensor system is comprised of an illumination unit that emits light, an optical element that controls the light from the illumination unit to a predetermined light distribution, a camera unit that detects the light reflected from each point on the object, and a calculation unit that calculates the distance to the object from the signal received by the camera unit. The illumination unit, camera unit, and calculation unit can use existing VCSELs, CMOS imagers, CPUs, etc., so the unique part of the system is the optical element.

[0004] Conventional optical elements have a problem in that the periodic structure of the microlens array causes uneven light intensity due to the effects of diffraction. To mitigate this unevenness, various methods have been devised, such as randomly arranging the lenses (see, for example, Patent Document 1).

[0005] On the other hand, TOF requires long-distance measurement, and the intensity of the irradiated light must be strong enough to enable such measurement. However, a randomly arranged microlens array is not suitable for long-distance measurement because the intensity is low due to the high uniformity of the irradiated light.

[0006] Therefore, as a method for saving power and processing strong light signals, it has been considered to use an optical element that irradiates a dot pattern and perform three-dimensional measurement from the time-of-flight of this light (for example, Patent Document 2).

[0007] Patent Publication No. 2006-500621 International Publication No. 2023 / 26987

[0008] Here, various considerations have been given to the parts of conventional optical elements that exhibit optical functions, but packaging and the like when manufacturing an optical system device in which the optical element is combined with an irradiation unit and other components has not yet been fully considered.

[0009] Therefore, the present invention relates to an optical element that can be easily packaged with other components, an optical system device using the optical element, and a method for manufacturing the optical system device.

[0010] In order to achieve the above object, the optical element of the present invention is an optical element having an uneven shape that exhibits an optical function at the interface between a first medium layer having a first refractive index and a second medium layer having a second refractive index higher than the first refractive index, and is characterized in that an adjustment section is formed on the first medium layer side of the uneven shape to keep a certain distance from the uneven shape.

[0011] Here, it is preferable that the first medium layer is a gas, and the second medium layer and the adjustment portion are integrally formed of a second resin having a second refractive index.

[0012] It is also preferable that the second medium layer is made of a second resin having a second refractive index, and that the first medium layer and the adjustment portion are integrally formed of a first resin having a first refractive index.

[0013] The surface of the first medium layer or the second medium layer opposite to the boundary surface is preferably flat or curved.

[0014] It is also preferable that an anti-reflection film be provided on the surface of the first medium layer or the second medium layer opposite to the boundary surface.

[0015] It is also preferable that a fine uneven structure functioning as a moth-eye is formed on the surface of the first medium layer or the second medium layer opposite to the boundary surface.

[0016] A third medium layer may be provided on the surface of the second medium layer opposite to the boundary surface.

[0017] The third medium layer may be made of the same material as the first medium layer.

[0018] The first medium layer is preferably formed on a substrate.

[0019] Furthermore, the substrate may be provided with one or more functional layers having specific functions on the surface opposite to the surface on which the first medium layer is provided.

[0020] The functional layer may also be an aperture mask.

[0021] The functional layer may be a metal wiring.

[0022] The functional layer may also be composed of metal wiring formed on the substrate, an insulating layer formed on the metal wiring, an aperture mask made of metal formed on the insulating layer, and a conductive portion that electrically connects the metal wiring and the aperture mask.

[0023] The uneven shape may be a shape in which lenses are periodically arranged.

[0024] Also, there is provided an optical element capable of diffusing incident light within a predetermined diffusion range, the diffusion range being defined as the interior of a single closed curve on a predetermined plane, the uneven shape having a plurality of ridges and valleys without periodicity, and the uneven shape being defined as a wavelength of the light λ and a refractive index of the first medium layer n １ When the refractive index of the second medium layer is n2, it is preferable that the uneven shape does not have a portion where the gradient of the uneven shape changes by 135 degrees within the width range of λ / (n2-n1), and that the uneven shape has a region with a gradient that causes incident light to be emitted to a region outside the diffusion range according to Snell's law, occupying 5% or less of the entire region.

[0025] The uneven shape is such that the light distribution calculated by Snell's law is cos －ｎ It is preferable that the angle is formed to be proportional to θ (1≦n≦7).

[0026] Furthermore, the optical system device of the present invention comprises the optical element of the present invention described above, and an irradiation unit that is arranged on the first medium layer side of the optical element and has a light source that irradiates the optical element with light, and is characterized in that the optical element and the irradiation unit are stacked via the adjustment unit.

[0027] Here, the irradiation section may include a light source covering layer made of resin and covering the light source.

[0028] The optical element and the light source may be provided with a cover that encloses the optical element and the light source. In this case, the cover may be made of a material that is at least partially light-blocking.

[0029] The concave-convex shape is a shape in which lenses that transmit light of wavelength λ are periodically arranged, the irradiating unit has a light source that irradiates a plurality of the lenses with light of wavelength λ, m and n are natural numbers of 1 or more, and the focal length of the cross-sectional shape of the lens perpendicular to the y direction is f １ , the focal length of the cross-sectional shape perpendicular to the x direction is f ２ , the size of the pitch of the lens in the x direction is P １ , the size of the pitch in the y direction is P ２ Then, the distance L between the irradiation unit and the first focal plane of the lens is １ , distance L to the second focal plane ２ is expressed by the following formula 1 and formula 2 It is preferable to satisfy the following.

[0030] Furthermore, the manufacturing method of the optical system device of the present invention is characterized by having a lamination process of laminating the above-mentioned optical element of the present invention and an irradiation section that is arranged on the first medium layer side of the optical element and has a light source that irradiates the optical element with light, via the adjustment section, and a cover section formation process of forming a cover section that encapsulates the optical element and the irradiation section.

[0031] Another method for manufacturing an optical system device according to the present invention is characterized by comprising: a first resin supplying step of supplying a first resin that is photocurable and has a first refractive index onto a substrate to which an irradiation unit is fixed; an unevenness shape forming step of forming an uneven shape on the surface of the first resin by an imprinting method; and a second medium layer forming step of supplying a second resin that is photocurable and has a second refractive index higher than the first refractive index onto the surface of the uneven shape and hardening the second resin to form a second medium layer.

[0032] The optical element of the present invention is formed with an adjustment section for maintaining a certain distance from the uneven shape of the optical element, and therefore can be easily packaged with the irradiation section and other components.

[0033] FIG. 1 is a schematic cross-sectional view showing an optical system element of the present invention. FIG. 2 is a schematic cross-sectional view showing another optical system element of the present invention. FIG. 3 is a schematic cross-sectional view showing yet another optical system element of the present invention. FIG. 4 is a schematic plan view showing functional layers of the optical system element of the present invention. (a) is a schematic cross-sectional view showing a conventional optical system device and (b) is a schematic cross-sectional view showing the optical system device of the present invention. (a) is a schematic cross-sectional view and (b) is a plan view showing the optical system element of the present invention having a plurality of functional layers. FIG. 5 is a schematic perspective view showing the optical element of the present invention. (b) is an enlarged cross-sectional view showing the optical element of the present invention. (c) is a view explaining the refraction of the optical element of the present invention. (d) is a schematic plan view showing the optical system device of the present invention. －ｎ Proportional to θ (n is 1 to 7) [P(θ) ∝ cos －ｎ θ]. FIG. 1 is a diagram showing the light intensity at the camera unit when the optical element of the present invention is integrated with an irradiation unit. FIG. 1 is a diagram showing the optical system device of the present invention ... in which a cover unit is formed. FIG. 2 is a diagram for explaining an example of the optical system device of the present invention. FIG. 2 is a diagram showing the schematic plan view showing the positional relationship between the irradiation unit and the optical element according to the present invention. FIG. 2 is a diagram showing the schematic cross-sectional view showing a method for manufacturing the optical system device of the present invention. FIG. 3 is a diagram showing the schematic cross-sectional view showing a method for manufacturing another optical system device of the present invention. FIG. 3 is a diagram showing the schematic cross-sectional view showing a method for manufacturing yet another optical system device of the present invention.

[0034] The optical element of the present invention will be described below. As shown in Figures 1 and 2, the optical element of the present invention has an optically functional concavo-convex shape 20 at the interface 11 between a first medium layer 1 having a first refractive index and a second medium layer 2 having a second refractive index higher than the first refractive index.

[0035] Furthermore, the optical element of the present invention has an adjuster 7 formed on the first medium layer 1 side of the concave-convex shape 20 (boundary surface 11) to maintain a certain distance from the concave-convex shape 20. Here, "certain distance" refers to the vertical and horizontal distances that must be maintained between the concave-convex shape 20 and the irradiation unit or other components when combined with the irradiation unit or other components. In particular, the vertical distance should be at least a distance that exceeds the height of the convex portions of the concave-convex shape 20 on the first medium layer 1 side. The presence of the adjuster 7 facilitates accurate vertical and horizontal alignment when combined with the irradiation unit or other components, facilitating packaging during the manufacture of optical devices. The adjuster 7 is preferably formed integrally with the first medium layer 1 or the second medium layer 2.

[0036] The difference between the first refractive index and the second refractive index may be any value as long as it can at least optically function the uneven shape 20. To widen the output angle of the lens, it is better to increase the difference between the first refractive index and the second refractive index, for example, to 1.8 or more, preferably 1.9 or more, and more preferably 2.0 or more.

[0037] In this case, in order to increase the refractive index difference, it is preferable that the first medium layer 1 be a gas, as shown in Figure 1. Any gas may be used, such as air or an inert gas. This gas also includes a gas in a reduced pressure state, such as a vacuum. The second medium layer 2 may be made of a material that can transmit at least light of a predetermined wavelength λ, such as a silicone resin, an epoxy resin, or an acrylic resin (hereinafter referred to as the second resin).

[0038] 1, the adjusting section 7 is formed on the periphery of the second medium layer 2 at a certain distance from the uneven shape 20, as the lower part of a side member 25 that determines the thickness (space thickness) of the first medium layer 1. Any material may be used for the side member 25. The second medium layer and the adjusting section 7 may also be integrally formed from a material having a second refractive index (for example, a second resin).

[0039] Such an optical element may be manufactured in any manner, for example, by using an imprinting method. Specifically, it may be manufactured by forming the concave-convex shape 20 in the material of the second medium layer using a mold having a pattern that is an inverse of the concave-convex shape 20 and the adjust portion 7. In this case, it is also possible to manufacture a plurality of optical elements by forming the concave-convex shape 20 and the adjust portion 7 in multiple regions and then dividing each region.

[0040] In addition, in optical elements, for example, there are cases where it is desired to narrow the angle of light emitted from a lens. To narrow the lens's emission angle, for example, it is possible to reduce the lens sag. However, there are limits to processing precision, making it difficult to reduce the lens sag beyond a certain level. In such cases, the refractive index difference between the first refractive index and the second refractive index may be reduced. This allows, for example, when the concave-convex shape 20 is a lens shape, to reduce the illumination angle while maintaining a large sag of the lens. The refractive index difference may be, for example, 0.4 or less, preferably 0.2 or less. This allows the illumination angle to be reduced to 30 degrees or less while maintaining the lens sag of 10 μm or more.

[0041] In this case, materials with a small difference in refractive index should be selected for the first medium layer 1 and the second medium layer 2. Any material can be used for the first medium layer 1 and the second medium layer 2 as long as it can transmit light of at least the predetermined wavelength λ, and examples of materials that can be used include silicone resin, epoxy resin, and acrylic resin.

[0042] 2, the adjuster 7 can directly utilize the surface 12 of the first medium layer 1 opposite the boundary surface 11. That is, the thickness of the first medium layer 1 may be set to a size that leaves a certain distance between the concave-convex shape 20 and the first medium layer 1 side.

[0043] Such an optical element may be manufactured in any manner, for example, by imprinting. Specifically, the optical element may be manufactured by forming the concave-convex shape 20 in the material of the first medium layer using a mold having a pattern that is an inverse of the concave-convex shape 20 and the adjuster 7, and then coating the material of the second medium layer on the mold. Alternatively, the concave-convex shape 20 may be formed in the material of the second medium layer, and then coating the material of the first medium layer on the mold. In this case, it is also possible to manufacture a plurality of optical elements by forming the concave-convex shape 20 over a large area or in multiple regions and then dividing the formed concave-convex shape 20.

[0044] The surface 21 of the second medium layer 2 opposite the boundary surface 11 can be formed flat as shown in FIG. 1( a) or FIG. 2( a). Alternatively, the surface 21 can be formed curved as shown in FIG. 1( b), (c) or FIG. 2(b), (c). Here, "flat" or "curved" means that the surface is sufficiently smooth and free of irregularities larger than the wavelength of the emitted light. Having a flat or curved surface makes it easier to add various functional layers, films, or shapes to the surface 21. For example, an anti-reflection film can be formed on the surface 21. This can reduce reflections of light emitted from the second medium layer 2. To reduce reflections, the surface 21 may be formed with a fine unevenness that functions as a moth-eye. The fine unevenness is formed to be smaller than the wavelength of the light passing through.

[0045] Furthermore, there are cases where it is desirable to protect the surface 21 on the side of the second medium layer 2 in order to improve the environmental performance of the first medium layer 1 and the second medium layer 2, such as their high-temperature and high-humidity characteristics and high-temperature-low-temperature thermal cycle characteristics. In such cases, a third medium layer 3 may be provided on the surface 21, as shown in Figures 1(d) and 2(d). For example, to create a wide-angle lens, the second medium layer 2 must be made of a resin with a high refractive index. However, high-refractive-index resins often have poor environmental performance. Therefore, by providing a third medium layer 3 on the surface of the second medium layer 2 that relieves stress in the second medium layer 2, the environmental performance of the optical element can be improved.

[0046] The third medium layer 3 may be made of any material that can improve the environmental performance of the first medium layer 1 or the second medium layer 2, such as silicone resin, epoxy resin, or acrylic resin. Preferably, the third medium layer 3 is made of the same material as the first medium layer 1.

[0047] As shown in FIG. 3 , the first medium layer 1 may be formed on a substrate 5. This allows one or more functional layers 6 with specific functions to be formed on the surface 52 of the substrate 5 opposite the surface 51 on which the first medium layer 1 is located. In this case, if the lower surface of the functional layer 6 is spaced a certain distance from the concave-convex shape 20, the lower surface of the functional layer 6 becomes the adjustment section 7. The substrate 5 may be, for example, a glass substrate. An intermediate resin layer 4A may be formed on the surface 51 of the substrate 5, as shown in FIG. 3( c). An example of the intermediate resin layer 4A is a resin layer serving as a base to improve adhesion between the substrate 5 and the second medium layer 2. The term "the first medium layer 1 is formed on the substrate 5" refers not only to the case in which the first medium layer 1 is in direct contact with the surface 51 of the substrate 5, as shown in FIGS. 3( a ) to 3 ( c ), but also to the case in which one or more intermediate resin layers 4B are sandwiched between the first medium layer 1 and the substrate 5, as shown in FIG. 3( d ). The intermediate resin layer 4B may be, for example, a resin layer serving as a base for improving the adhesion between the substrate 5 and the first medium layer 1.

[0048] The functional layer 6 may be any material having a specific function, such as an aperture mask 61 as shown in FIG. 4( a). The aperture mask 61 has an opening 61 a and is used to block a portion of the light. This prevents electromagnetic waves that may cause noise from emitting from any area other than the opening 61 a. The aperture mask 61 may be made of a metal such as gold.

[0049] Another example of the functional layer 6 is metal wiring 62, as shown in FIG. 4(b). The metal wiring 62 constitutes a predetermined electrical circuit, etc. Conventionally, as shown in FIG. 5(a), metal wiring 62 is formed on the underside 52 of the substrate 5, and a lens-like texture 20 is formed on the surface resin layer 2A. In this case, the metal wiring 62 is insulated by the resin layer 2A, so a separate conductive structure is required to establish electrical continuity with the package. In contrast, the optical element of the present invention, as shown in FIG. 5(b), forms the lens-like texture 20 on one side 51 of the substrate 5 and the metal wiring 62 on the other side 52, allowing the metal terminals of the metal wiring 62 to be exposed on the surface. Therefore, a structure for establishing electrical continuity with the package, such as the irradiation unit 8, is not required, and direct connection to the package contacts is possible. For example, ITO or the like can be used for the metal wiring 62.

[0050] The functional layer 6 may also be a combination of layers having a specific function. For example, as shown in FIG. 6( a), the functional layer may be composed of metal wiring 62 such as ITO formed on the surface 52 of the substrate 5, an insulating layer 63 formed on the metal wiring 62, an aperture mask 61 made of metal formed on the insulating layer 63, and a conductive portion 64 electrically connecting the metal wiring 62 and the aperture mask 61. This provides the optical element with eye-safe and EMI-compliant functions. Furthermore, forming the aperture mask 61 from metal facilitates connection between the contacts on the package side and the metal wiring 62.

[0051] The concave-convex shape 20 of the optical element may be any shape that has an optical function. For example, a shape that can control incident light and emit it, such as a microlens array (MLA) or a diffractive optical element (DOE), is suitable. The lenses of the microlens array may be arranged periodically or randomly.

[0052] As an example of the uneven shape 20, an optical element 100 capable of diffusing incident light within a predetermined diffusion range 91 will be described below as shown in Fig. 7. The diffusion range 91 of the optical element 100 is defined as the interior of a single closed curve on a predetermined plane. Furthermore, the uneven shape 20 has multiple ridges and valleys that do not have periodicity, as shown in Fig. 8.

[0053] Here, the diffusion range 91 is defined as the interior of a single closed curve 92, such as a polygon or an ellipse, on a predetermined plane 90. The predetermined plane 90 here refers to a plane (xy plane) perpendicular to the optical axis (z axis) of the light source that irradiates the optical element with light, and which is at least 100 times the size of the light emitted from the light source 2 and is away from the optical element.

[0054] The uneven surface 20 is formed so as to refract incident light within a diffusion range 91 according to Snell's law. This will be explained using Figure 9. For simplicity's sake, consider an optical element in which the exit surface 21 is a flat surface (xy plane) and the entrance surface 18 has an uneven surface 20 defined by z = f(x, y). Also, assume that light enters the entrance surface in a direction perpendicular to the xy plane (z-axis direction).

[0055] First, the incident angle θ of light with respect to the incident surface 22 of the optical element １ and the refraction angle θ of the refracted light in the optical element ２ From Snell's law, n １ Similarly, the relationship sinθ1=n2sinθ2 holds. Similarly, the incident angle θ ３ and the refraction angle θ of the emitted light ４ Therefore, if the refractive index of the first medium layer 1 of the optical element is n １ , the refractive index of the second medium layer 2 is n2, and the refractive index of air is n3, then n １ sin θ1 = n2 sin θ2, and n2 sin θ3 = n3 sin θ4. Also, as shown in FIG. １ That is, the exit angle θ4 can be calculated from Snell's law of the incident surface 22 and the exit surface 21 of the optical element, and therefore, θ ４ = g(θ １ ) can be expressed as follows. For example, the incident angle θ１ is sufficiently small, and n １ θ １ = n2θ ２ , n2θ3 = n3θ4, if θ ４ = θ １ (n2-n １ ) / n3.

[0056] In this way, the light distribution of the emitted light, that is, the emission angle θ ４ 9, the intensity distribution of the incident angle θ1 has a one-to-one relationship with the frequency distribution of the incident angle θ1. Also, as shown in FIG. 9, the incident angle θ1 is proportional to the inclination angle θ of the concave-convex surface of the optical element (the surface of the concave-convex shape 20). １ (gradient) is the same as the incident angle θ １ The frequency distribution of the inclination angle θ of the concave and convex surface of the optical element １ corresponds to the frequency distribution of

[0057] Also, the partial derivative of z with respect to x and y, ∂z / ∂x| ｙ＝ｙｏ , ∂z / ∂y| ｘ＝ｘｏ are respectively y = y ｏ , x=x ｏ Therefore, when light is incident perpendicularly to the incident surface of the optical element, y = y ｏ The incident angle of the surface is θ ｉｘ , x=x ｏ The angle of incidence on the surface is θ ｉｙ Then, tanθ ｉｘ = ∂z / ∂x| ｙ＝ｙｏ , tanθ ｉｙ = ∂z / ∂y| ｘ＝ｘｏ Therefore, θ ｉｘ = arctan(∂z / ∂x| ｙ＝ｙｏ ), θ ｉｙ = arctan(∂z / ∂y| ｘ＝ｘｏ ) can be expressed as

[0058] On the other hand, y=y of the light emitted from the optical element ｏ The exit angle of the surface is θ ｏｘ , x=x ｏ The exit angle at the surface is θ ｏｙ Then, as mentioned above, the incident angle θ ｉｘ and the output angle θ ｏｘ , incident angle θ ｉｙ and the output angle θ ｏｙSince Snell's law holds between ｏｘ = g (θ ｉｘ ), θ ｏｙ = g (θ ｉｙ ) can be expressed as

[0059] In addition, the light intensity distribution h(θ ｏ ) is θ ｏ Using the frequency function FREQUENCY(θ), h(θ ｏ ) = FREQUENCY (θ ｏ ) Therefore, by combining these relationships, the light intensity distribution h(θ ｏｘ ) is h(θ ｏｘ ) = FREQUENCY (θ ｏｘ ) = FREQUENCY(g(θ ｉｘ ))=FREQUENCY(g(arctan(∂z / ∂x| ｙ＝ｙｏ ))) becomes.

[0060] Similarly, the light intensity distribution h(θ ｏｙ ) is h(θ ｏｙ ) = FREQUENCY (θ ｏｙ ) = FREQUENCY(g(θ ｉｙ ))=FREQUENCY(g(arctan(∂z / ∂y| ｘ＝ｘｏ ))) becomes.

[0061] From the above, in order to realize a predetermined light intensity distribution, the tilt angle θ of the optical element surface is １ The uneven shape 20 can be designed by calculating the frequency distribution of the gradient (gradient) of the incident light to the area outside the diffusion range 91. In this case, the uneven shape 20 should be designed so that, when calculated according to Snell's law, the area having a gradient that causes incident light to be emitted to the area outside the diffusion range 91 is 5% or less of the entire area, preferably 3% or less, and more preferably 1% or less.

[0062] In order for the optical element to function as a diffuser, the wavelength in vacuum of the light incident on the optical element is λ, and the refractive index of the first medium layer 1 is n １ , the refractive index of the second medium layer 2 is n ２ Then, the uneven shape 20 is at least λ / (n ２ -n １) is preferably 2.5 times or more, more preferably 5 times or more, and even more preferably 10 times or more. The height of the uneven shape 20 here means the difference between the highest ridge and the lowest valley of the uneven shape 20.

[0063] In addition, the surface of the uneven shape 20 has an inclination angle θ １ If there is a portion where the gradient changes suddenly, it is not preferable because it will be affected by scattering, diffraction, etc. Therefore, the inclination angle θ １ Specifically, the inclination angle θ of the surface of the uneven shape 20 is preferably gradually changed. １ The inclination angle θ is preferably 135 degrees, more preferably 120 degrees, and even more preferably 90 degrees. １ The change in the refractive index of the first medium layer 1 can be ignored if it is a change in a magnitude that is not perceptible to light. １ , the refractive index of the second medium layer 2 is n ２ Then, the inclination angle θ of the surface of the uneven shape 20 is １ is the width λ / (n ２ -n １ Here, the width means the width in the direction perpendicular to the z-axis of the uneven shape 20 (the direction parallel to the entrance surface or exit surface).

[0064] As shown in FIG. 10 , a typical sensor system mainly comprises an optical element 100, an illumination unit 8, a camera unit 300 that detects light reflected from each point on the object 10, and a calculation unit 400 that calculates the distance to the object from the signal received by the camera unit 300. Here, the light intensity decreases as the angle of reflection increases and the incident light enters the camera unit 300. Therefore, in order for the camera to properly detect light incident from a wide angle, it is preferable that the light intensity of the light passing through the optical element 100 increases as the angle θ increases. In other words, it is preferable that the light intensity of the light in the far field from the optical element 100 increases as the angle θ increases. Therefore, it is preferable that at least the concave-convex shape 20 be formed so that the light distribution calculated by Snell's law monotonically increases from the center of the diffusion range 91 toward the boundary. To achieve this, the concave-convex shape 20 of the optical element can be designed so that the frequency distribution of the tilt monotonically increases with increasing tilt.

[0065] In this specification, the center of diffusion range 91 refers to the position of the intersection between the optical axis of light source 2 and diffusion range 91 when light from light source 2 is irradiated perpendicularly onto the optical element of the present invention. The boundary of diffusion range 91 is the portion corresponding to the closed curve 92 described above, and refers to the position of the maximum peak in the light intensity distribution on the cross section.

[0066] In addition, in an optical system in which light emitted from the optical element 100 is reflected by a screen and returns to a camera, if the reflection on the screen is a Lambertian reflection, in order to make the intensity of the light returning to the camera uniform with respect to the angle θ, the light intensity distribution P(θ) in the far-field from the optical element 100 must be calculated by multiplying it by cos －７ Proportional to θ [P(θ)∝cos －７ Therefore, the light distribution of the light emitted from the light source 2 and transmitted through the optical element 100 is cos －７ It is most preferable to make it proportional to θ.

[0067] FIG. 11 shows an optical system in which light transmitted through an optical element 100 is reflected by a screen and returns to a camera. The light intensity distribution P(θ) in the far field from the optical element 100 is expressed as cos －ｎProportional to θ (n is 1 to 7) [P(θ) ∝ cos －ｎ This is a graph showing the calculated intensity of light returning to the camera unit with respect to the incident angle θ when the incident angle is increased. The larger the incident angle, the smaller the light intensity, but the larger n, the smaller the difference. In addition, when the light intensity distribution P(θ) is calculated as cos －７ Proportional to θ [P(θ)∝cos －７ θ], the intensity of the light returning to the camera becomes uniform with respect to the angle θ.

[0068] However, when irradiating light over a wide angle, the cos －７ Since it is difficult to make it proportional to θ, it is necessary to use cos －ｎ A light intensity distribution proportional to θ (1≦n≦7) is also acceptable.

[0069] Therefore, the concave-convex shape 20 of the optical element has a light distribution calculated by Snell's law that is cos －ｎ It is preferable that the angle is formed to be proportional to θ (1≦n≦7), and preferably, to be cos －７ It is preferable that the angle of inclination of the concave-convex shape 20 of the optical element is proportional to θ. １ The frequency distribution of cos －ｎ θ １ (1≦n≦7), and preferably, －７ θ １ is formed in proportion to

[0070] It should be noted that a larger uneven shape 20 is preferable in that it can reduce the influence of the wave properties of light. Specifically, each uneven shape 20 should have a height of at least 5 times λ / (n2-n1), preferably 10 times or more, and more preferably 25 times or more.

[0071] Next, the optical system device of the present invention will be described. As shown in Figures 5(b), 6(a), 12 and 13, the optical system device of the present invention includes the optical element of the present invention described above and an irradiation unit 8 that is arranged on the first medium layer 1 side of the optical element and irradiates the optical element with light. The optical element and the irradiation unit 8 are stacked via an adjustment unit 7.

[0072] Here, the irradiation unit 8 may be any device having a light source 80 that irradiates light of wavelength λ. The irradiation unit 8 may be a single light source or multiple light sources. Alternatively, multiple light sources may be used by passing light from a single light source through an aperture having multiple fine holes. When the irradiation unit 8 is configured with multiple light sources, it is preferable that the light sources 80 are formed on the same plane, since this allows for accurate adjustment of the distance and angle between the optical element and the irradiation unit 8. A specific example of the irradiation unit 8 is a VCSEL (Vertical Cavity Surface Emitting Laser), which can achieve high output with low power consumption. VCSELs include single-emitter VCSELs that have one light source 80 that can irradiate light in a direction perpendicular to the light-emitting surface, and multi-emitter VCSELs that have multiple light sources 80. Furthermore, it is preferable to form a light-absorbing film on areas other than the light source 80 to prevent noise due to reflected light.

[0073] Furthermore, as shown in Figure 12, it is preferable that the irradiation unit 8 is formed integrally with the adjustment unit 7 of the optical element of the present invention by abutting it. This makes it possible to provide a highly reliable optical system device in which the distance, angle, etc. between the optical element and the irradiation unit 8 are adjusted. In particular, in order to demonstrate the optical function of the concave-convex shape 20 of the optical element, it may be necessary to adjust the position of the optical element relative to the irradiation unit 8. In this case, the optical system device can be formed integrally with the irradiation unit 8 to maintain an appropriate distance between the optical element and the adjustment unit 7 by utilizing the adjustment unit 7.

[0074] Note that the irradiation unit 8 often generates heat when emitting light. As in the past, if a gas with low thermal conductivity exists between the optical element and the irradiation unit 8, the performance of the irradiation unit 8 and the optical element may be degraded or damaged. Therefore, as shown in FIG. 13 , the irradiation unit 8 may include a light source coating layer 85 made of resin that covers the light source 80. Resin has a higher thermal conductivity than gas, thereby improving the heat dissipation of the light source. Furthermore, resin can have a smaller refractive index difference with the material of the light source 80 than gas, thereby improving the light extraction efficiency of the light source 80. Furthermore, since the light source 80 is covered by the light source coating layer 85, the light source 80 is less likely to be exposed even if the optical device is damaged, which is preferable from an eye-safe perspective. Furthermore, a micro-convexo-concave structure that functions as an anti-reflection film or a moth-eye can be formed on the surface of the light source coating layer 85. This reduces reflection when light is emitted from the light source coating layer 85. The resin constituting the light source covering layer 85 may be any resin that can transmit at least light of wavelength λ and can exert the optical function of the uneven shape 20, and examples thereof include silicone resin, epoxy resin, and acrylic resin. It is also possible to use a resin as a base that improves adhesion between the irradiation unit 8 and the material of the first medium layer 1 or the second medium layer 2. The surface of the light source covering layer 85 may also include a substrate such as glass or a metal layer.

[0075] Furthermore, it is preferable that the light source covering layer 85 be formed to a thickness that provides a constant distance from the light source 80 to the surface 86 of the light source covering layer 85. This allows for easy and accurate vertical and horizontal alignment when combined with optical elements and other components, facilitating packaging during the manufacture of an optical system. For example, as shown in Figures 13(a) and 13(b), if the adjuster 7 of the optical element and the surface 86 of the light source covering layer 85 are formed integrally in contact with each other, a highly reliable optical system can be provided in which the distance, angle, etc. between the optical element and the irradiation unit 8 are adjusted.

[0076] It is also possible to use the first medium layer 1 in common with the light source covering layer 85. In this case, as shown in Figure 13(c), the space between the concave and convex shapes 20 can be filled with only the material of the first medium layer 1, and the layer can be formed integrally with the optical element. In this case, the boundary between the first medium layer 1 and the irradiation portion 7 becomes the adjustment portion 7.

[0077] The optical system device of the present invention may also include a cover 150 containing the optical element and the irradiation unit 8, as shown in FIG. 14 . Enclosing the light source 80 in the cover 150 reduces the likelihood of the light source 80 being exposed even if the optical system device is damaged, which is preferable from the viewpoint of eye safety. The resin constituting the cover 150 may be any resin that is transmissive to at least light of wavelength λ and that can exert the optical function of the uneven surface 20. Examples of suitable resins include silicone resins, epoxy resins, and acrylic resins. When the first medium layer 1 is a gas, the side members 25 are formed around the periphery of the second medium layer 2 so as to seal the gas that will become the first medium layer 1 between the irradiation unit 8 and the second medium layer.

[0078] When a resin with a high refractive index is used for the second medium layer, the resin may contain titanium oxide (TiO ２ ) may be used. However, titanium oxide functions as a photocatalyst, and therefore has the problem of decomposing the resin when exposed to light such as ultraviolet light. In this case, a light-blocking material that suppresses the transmission of light such as ultraviolet light may be used for the material that constitutes at least a part of the cover portion 150 or the material that covers the cover portion 150.

[0079] The cover 150 may be integrally formed from the same material, or may be formed from different materials for each portion, such as the top surface, side surfaces, etc. For example, the side surfaces may be formed from a light-blocking material, and the top surface may be formed from a material that transmits only infrared rays.

[0080] Next, an optical system for projecting a dot pattern will be described as an example of the optical system of the present invention. The optical element used in the optical system is an optical element having a concave-convex pattern 20 with periodically arranged lenses 21 that transmit light of wavelength λ at an interface 11 between a first medium layer 1 having a first refractive index and a second medium layer 2 having a second refractive index higher than the first refractive index, as shown in Fig. 15. Fig. 15(a) shows an example of an optical system in which the first medium layer 1 is gas and the second medium layer is resin, while Fig. 15(b) shows an example of an optical system in which both the first medium layer 1 and the second medium layer are resin.

[0081] The lens 21 has a focal point on the first medium layer 1 side, at a predetermined distance f (f>0) from the lens 21. The optical element of the present invention can improve contrast as the focal length f increases, such as 10 μm or more, 20 μm or more, 40 μm or more, or 60 μm or more. Hereinafter, the position of a plane that includes the focal point of the lens 21 and is perpendicular to the optical axis of the lens will be referred to as the focal position 25 of the optical element.

[0082] The shape of the lens 21 can be freely designed to match the spreading pattern of the dots to be projected (hereinafter referred to as the dot pattern). For example, if a circular dot pattern is desired, the shape of the lens 21 can be a spherical lens. Also, if a non-circular dot pattern is desired, the shape of the lens 21 can be an appropriately designed aspherical lens. In the case of an aspherical lens, the focal length differs depending on the direction. Figure 15(c) shows a cross-sectional shape perpendicular to the y direction where the focal length is f １ , the focal length due to the cross-sectional shape perpendicular to the x direction is f ２ (f １ ≠f ２ ), the pitch in the x direction is P １ , the size of the pitch in the y direction is P ２ This is an example of an aspherical lens. The lens shape may be a convex lens, a concave lens, or the like. In the case of a convex lens, it is preferable that the convex lens portion faces the irradiation unit 8 side.

[0083] 16, the periodic arrangement of the lenses 21 may be a square arrangement of lenses 21 that are square or rectangular in plan view, or a hexagonal arrangement of lenses 21 that are hexagonal in plan view. The lenses 21 may be any type that functions as a lens, and may be, for example, a Fresnel lens, a DOE lens, or a metalens. The lenses 21 may be provided with an anti-reflection coating that prevents reflection of light from the irradiation unit 8.

[0084] The irradiation unit 8 has a light source 80 that irradiates a plurality of lenses 21 with light of wavelength λ. The irradiation unit 8 may be a single light source or multiple light sources. When one irradiation unit 8 includes multiple light sources 80, it is preferable that the light sources 80 are formed on the same plane. Furthermore, when one irradiation unit 8 includes multiple light sources 80, it is necessary to arrange them so that the number of light sources 80 for each lens 21 of the optical element is the same in a planar view even when each light source 80 and the optical element are moved in parallel relative to each other. To achieve this, when the positions of each light source 80 relative to the lens 21 are superimposed on one lens and aggregated, the apparent positions of the aggregated light sources 80 may be formed to match each other. For example, the light sources included in the same irradiation unit are periodically arranged, and the pitch P of the light sources in the x direction is ｘ is the lens pitch P １ and the pitch P in the y direction ｙ is the lens pitch P ２ In other words, the light sources 80 included in the same irradiation unit 8 may be configured such that the pitch in the x direction is P ｘ , the size of the pitch in the y direction is P ｙ Let j and k be natural numbers equal to or greater than 1. ｘ =jp １ or jP ｘ =P １ and P ｙ = kP ２ or kP ｙ =P ２ 16(a) and 16(b) show the arrangement of the light sources 80 with a pitch P ｘ , P ｙ The pitch P of the lenses 21 of the optical element 2１ , P ２ 14(c) shows the pitch P ｘ , P ｙ The pitch P of the lenses 21 of the optical element 2 １ , P ２ 14(d) shows the pitch P ｘ , P ｙ The pitch P of the lenses 21 of the optical element 2 １ , P ２ This is twice the amount.

[0085] The irradiation unit 8 and the optical element 2 are arranged so that the optical axis direction of the light source 80 of the irradiation unit 8 and the optical axis direction of the lens 21 of the optical element 2 are aligned.

[0086] [Positional Relationship Between Irradiation Unit and Optical Element] As shown in FIG. 15, the distance L between the irradiation unit 8 and the first focal plane 251 of the lens 21 is １ , the distance L to the second focal plane 252 ２ can convert incident light into a dot pattern with high contrast when the following formulas α and β are satisfied: where m and n are natural numbers equal to or greater than 1, １ is the pitch of the lens 21 in the x direction, P ２ is the pitch in the y direction, λ is the wavelength of the light incident from the irradiation unit 8, f １ is the focal length of the lens 21 due to the cross-sectional shape perpendicular to the y direction, and f ２ is the focal length of the cross-sectional shape of the lens 21 perpendicular to the x-direction, and a, b, c, and d are coefficients indicating allowable errors. The first focal plane 251 is a plane that is perpendicular to the optical axis (z-direction) of the lens 21 and is located at the focal position of the cross-sectional shape of the lens 21 perpendicular to the y-direction. The second focal plane 252 is a plane that is perpendicular to the optical axis (z-direction) of the lens 21 and is located at the focal position of the cross-sectional shape of the lens 21 perpendicular to the x-direction. When the focal points are on both sides of the lens 21, it is preferable to use the first focal plane 251 and the second focal plane 252 as references located on the irradiation unit 8 side of the lens 21. Furthermore, the distance L １ , L ２means the distance (optical path length) that light travels in a vacuum in the same time as it travels through a medium, and is expressed as the product NL, where N is the refractive index of the medium and L is the actual distance.

[0087] Here, the coefficients a, b, c, and d of formulas α and β are preferably as small as possible, such as 1, 0.5, 0.3, and 0.1. When the coefficients of formulas α and β are a = b = c = d = 1, formulas α and β become formulas 1 and 2 below, respectively.

[0088] In addition, the distance L １ , L ２ can most effectively strengthen the light when the following formulas 3 and 4 are satisfied, where a=b=c=d=0.

[0089] It is preferable that the adjuster 7 of the optical element of the present invention is formed so that the predetermined distance is maintained between the uneven shape 20 and the illumination unit, taking into consideration formulas 1 and 2, and preferably formulas 3 and 4.

[0090] In addition, pitch P １ , P ２ If the pitch P is too small compared to the wavelength λ of the light from the light source 80, diffraction is difficult to occur. Therefore, as long as the light distribution angle of the light source 80 includes a sufficient number of lenses 21 to cause diffraction, the pitch P １ , P ２ is preferably sufficiently larger than the wavelength λ of the light from the light source 80, for example, 5 times or more, and preferably 10 times or more.

[0091] Furthermore, the optical element for irradiating the dot pattern described above can be used not only for irradiating the dot pattern but also for use as a diffuser. When the optical element 2 is used as a diffuser, the distance L between the irradiation unit 8 and the focal position 25 of the optical element is １ , L ２ The optical system device may be configured by arranging or integrating the irradiation unit 8 and the optical element so that at least the formula 1 and the formula 2 are not satisfied.

[0092] [Method of Manufacturing Optical Device] Next, a method of manufacturing the optical device of the present invention will be described. First, as shown in FIG. 17( a), an irradiation unit 8 and an optical element are prepared and appropriately aligned. Next, as shown in FIG. 17( b), an adjustment unit 25 is abutted against and bonded to the irradiation unit 8. At this time, if the height of the adjustment unit 25 is appropriately formed in advance, alignment in the z direction can be achieved simply by abutting the adjustment unit 25. Note that the optical device can be formed by forming a single pair of irradiation unit 8 and optical element. However, as shown in FIG. 17, it is also possible to stack an optical element member in which multiple optical elements are integrally formed and an irradiation unit member in which multiple irradiation units 8 are integrally formed together. In this case, after the optical element member and irradiation unit member are stacked and bonded, they can be cut as shown in FIG. 17( c) to separate them into individual optical device units.

[0093] Furthermore, when forming the cover section 150 containing the optical element and the irradiation section 8, for example, an optical system is first placed on a substrate, as shown in FIG. 18( a), for example. Next, as shown in FIG. 18( b), a fluid material for the cover section 150 is supplied onto the optical system, covering it, and then solidified to form the cover section 150. Note that when the first medium layer 1 is a gas, the above-mentioned side members 25 are formed on the periphery of the second medium layer 2 so as to seal the gas that will become the first medium layer 1 between the irradiation section 8 and the second medium layer. This makes it possible to prevent the material for the cover section 150 from entering the space that will become the first medium layer 1.

[0094] Furthermore, the cover portion 150 can be formed for each optical device, but it is also possible to form the cover portion 150 for a plurality of optical devices at once, as shown in Fig. 18. In this case, after the cover portion 150 is formed, it can be cut as shown in Fig. 18(c) and divided into individual optical devices.

[0095] Next, a method for manufacturing another optical device of the present invention will be described in which the first medium layer 1 is also used as the light source covering layer 85. This manufacturing method comprises a first resin supplying step, a concave-convex shape forming step, and a second medium layer forming step.

[0096] The first resin supplying step supplies the material of the first medium layer 1 onto a substrate to which the irradiation unit is fixed. For example, a photocurable first resin 19 having a first refractive index is supplied. First, as shown in Figures 19(a) and 19(b), an irradiation unit 8 such as a VCSEL is fixed onto a substrate 55 such as a lead frame by die bonding and electrically connected by wire bonding to prepare a substrate 55 to which the irradiation unit 8 is fixed. Next, as shown in Figure 19(c), a photocurable first resin 19 is supplied onto the irradiation unit 8 side of the substrate 55.

[0097] The uneven shape forming step involves forming an uneven shape 20 on the surface of a first resin 19 by an imprinting method. As shown in Fig. 19(d), a mold 50 having a pattern 20A similar to the uneven shape 20 is pressed onto the first resin 19, thereby forming the uneven shape 20 on the first resin 19. Next, as shown in Fig. 19(e), the first resin 19 is cured and the mold 50 is released, forming a first medium layer 1 having a first refractive index.

[0098] The second medium layer forming step is to form the second medium layer 2 by supplying a material for the second medium layer having a second refractive index higher than the first refractive index onto the surface of the concave-convex shape 20. Specifically, as shown in Fig. 19(f), a photo-curable second resin 29 is applied to the surface 21 of the concave-convex shape 20. Next, as shown in Fig. 19(g), the second resin 29 is cured to form the second medium layer 2 having the second refractive index higher than the first refractive index.

[0099] The optical system device thus formed can be divided appropriately to manufacture an optical system device such as that shown in FIG. 15(h).

[0100] REFERENCE SIGNS LIST 1 First medium layer 2 Second medium layer 3 Third medium layer 4A, 4B Intermediate medium layer 5 Base material 6 Functional layer 7 Adjustment portion 8 Irradiation portion 11 Boundary surface 19 First resin 20 Concave and convex shape 29 Second resin 61 Aperture mask 62 Metal wiring 63 Insulation layer 64 Conduction portion 80 Light source 85 Irradiation portion side medium layer 150 Cover portion

Claims

1. an optical element having an uneven shape exhibiting an optical function at an interface between a first medium layer having a first refractive index and a second medium layer having a second refractive index higher than the first refractive index; an irradiation unit disposed on the first medium layer side of the optical element and having a light source that irradiates the optical element with light, An optical system device, characterized in that the optical element and the irradiation unit are laminated with the first medium layer to maintain a certain distance from the uneven shape.

2. An optical system device as described in claim 1, characterized in that the first medium layer is made of a first resin having a first refractive index, and the second medium layer is made of a second resin having a second refractive index.

3. 3. The optical system according to claim 1, wherein the optical element includes an anti-reflection film on a surface of the first medium layer or the second medium layer opposite to the boundary surface.

4. 3. The optical system according to claim 1, wherein a fine uneven structure functioning as a moth-eye is formed on a surface of the first medium layer or the second medium layer opposite to the boundary surface.

5. 3. The optical system according to claim 1, wherein the optical element comprises a third medium layer on a surface of the second medium layer opposite to the boundary surface.

6. 6. The optical system according to claim 5, wherein the third medium layer is made of the same material as the first medium layer.

7. 3. The optical system according to claim 1, wherein the uneven shape is a shape in which lenses are periodically arranged.

8. The optical element is capable of diffusing incident light to a predetermined diffusion range, The diffusion range is defined as the interior of a single closed curve in a given plane; The uneven shape has a plurality of ridges and valleys that do not have periodicity, The concave and convex shape is such that the wavelength of the light is λ and the refractive index of the first medium layer is n １ , the refractive index of the second medium layer is n 2 In this case, there is no portion where the gradient of the uneven shape changes by 135 degrees within the width range of λ / (n2-n1), 3. The optical system according to claim 1, wherein the uneven shape has a region having a gradient that causes incident light to exit to a region outside the diffusion range according to Snell's law, the region occupying 5% or less of the entire region.

9. The uneven shape is such that the light distribution calculated by Snell's law is cos －ｎ 9. The optical system according to claim 8, wherein the optical system is formed to be proportional to θ (1≦n≦7).

10. the concave-convex shape is a shape in which lenses that transmit light of wavelength λ are periodically arranged, the irradiation unit has a light source that irradiates light of wavelength λ onto a plurality of the lenses, m and n are natural numbers of 1 or more, and the focal length of the lens according to the cross-sectional shape perpendicular to the y direction is f １ , the focal length due to the cross-sectional shape perpendicular to the x-direction is f ２ , the size of the pitch of the lens in the x direction is P １ , the size of the pitch in the y direction is P ２ Then, the distance L between the irradiation unit and the first focal plane of the lens is １ , distance L from the second focal plane ２ is represented by the following formula 1 and formula 2 [0010] [0025] 3. The optical system according to claim 1, wherein the following is satisfied:

11. 3. The optical system according to claim 1, wherein the irradiation section includes a light source covering layer made of resin and covering the light source.

12. 3. The optical system device according to claim 1, further comprising a cover portion that encloses the optical element and the irradiation portion.

13. 13. The optical system according to claim 12, wherein at least a part of the cover is made of a material having a light-shielding property.

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