WO2025169837A1 - Optical element and light source device - Google Patents

Abstract

The present invention increases the light extraction efficiency of diffused light and reduces light having locally high luminous intensity. An optical element (100) comprises a base material (1) including a first surface (1a) and a second surface (1b) positioned at a side opposite of the first surface. The base material (1) comprises, on at least a portion of the first surface (1a) and the second surface (1b): an optical region (10) in which at least one optical element (11) is disposed; and a peripheral region (12) in which the optical element (11) is not disposed, the peripheral region (12) being provided surrounding the optical region on the surface of the base material on which the optical region is provided. The optical element (11) is a lens element, and if one cross-sectional region of the at least one optical element, the cross-sectional region including the optical axis of the optical element closest to the peripheral region, and extending from the vertex of the optical element through which the optical axis passes to the end closest to the optical element in the peripheral region, is defined as a boundary region (110), the slope of the surface in the boundary region (110) has an average absolute value of 1.00 or less and a variation σ of 0.10 or greater.

Description

Optical element and light source device

This disclosure relates to optical elements and light source devices.

Optical elements such as lens arrays that diffuse incident light and emit diffused light are known. Light source devices that include such optical elements are also known.

For example, Patent Document 1 discloses an optical element that includes an optical region in which optical elements are arranged on a portion of at least one surface of a flat substrate, and a peripheral region in which no optical elements are arranged, which is arranged around the optical region on the surface of the substrate where the optical region is arranged.

International Publication No. 2022/202514

However, with the optical element described in Patent Document 1, light incident on the boundary region between the optical region and the peripheral region is totally reflected by the optical element, and an increase in the amount of light returning in the direction of incidence can reduce the light extraction efficiency of diffused light emitted from the optical element. Furthermore, with the optical element described in Patent Document 1, light incident on the boundary region between the optical region and the peripheral region can be locally concentrated, resulting in light with locally high luminous intensity being emitted from the optical element.

One aspect of the present disclosure aims to increase the light extraction efficiency of diffused light and reduce light with locally high luminous intensity.

An optical element according to one aspect of the present disclosure has a substrate including a first surface and a second surface located opposite the first surface, the substrate including an optical region in which at least one optical element is arranged in a portion of at least one of the first and second surfaces, and a peripheral region in which the optical element is not arranged, the optical element being a lens element, and in a cross section including the optical axis of the optical element closest to the peripheral region, the cross-sectional region extending from the vertex of the optical element through which the optical axis passes to the end of the peripheral region closest to the optical element being defined as a boundary region, the average absolute value of the slope of the surface in the boundary region being 1.00 or less and the variation σ being 0.10 or more.

According to one aspect of the present disclosure, it is possible to increase the light extraction efficiency of diffused light and reduce light with locally high luminous intensity.

1 is a schematic top view showing the overall configuration of an optical element according to a first embodiment. FIG. 2 is a schematic cross-sectional view of the optical element taken along line II-II in FIG. 5A and 5B are schematic diagrams showing the relationship between the inclination of the surface and the diffusion angle in the boundary region of the optical element according to the first embodiment. FIG. 2 is a diagram showing an example of the area ratio between the substrate and the optical region in the optical element according to the first embodiment. 10A and 10B are diagrams showing other examples of the area ratio between the substrate and the optical region in the optical element according to the first embodiment. 1 is a top view photograph showing an optical element according to Example 1. FIG. 7 is a diagram showing a cross-sectional shape of the optical element taken along line VII-VII in FIG. 6. FIG. 8 is an enlarged view of region VIII in FIG. 7. FIG. 9 is a diagram showing the first derivative of FIG. 8 . FIG. 8 is a diagram showing the probability density of the diffusion angle of light incident on region VII in FIG. 7 . 10 is a top view photograph showing an optical element according to Example 2. 12 is a diagram showing a cross-sectional shape of the optical element taken along line XII-XII in FIG. 11. FIG. 13 is an enlarged view of region XIII in FIG. 12. FIG. 14 is a diagram showing the first derivative of FIG. 13 . FIG. 13 is a diagram showing the probability density of the diffusion angle of light incident on region XIII in FIG. 12 . FIG. 10 is a perspective view showing the behavior of light incident on a boundary region of an optical element according to Example 3. 10A and 10B are side views showing the behavior of light incident on a boundary region of an optical element according to Example 3. 10 is a diagram showing light irradiated onto an irradiation surface when light is incident on a boundary region of an optical element according to Example 3 at a first surface incident angle of 10 degrees. FIG. 10 is a diagram showing light irradiated onto an irradiation surface when light is incident on a boundary region of an optical element according to Example 3 at a first surface incident angle of 20 degrees. FIG. 10 is a diagram showing light irradiated onto an irradiation surface when light is incident on a boundary region of an optical element according to Example 3 at a first surface incident angle of 30 degrees. FIG. FIG. 10 is a perspective view showing the behavior of light incident on a boundary region of the optical element according to Example 1. 10 is a side view showing the behavior of light incident on a boundary region of the optical element according to Example 1. FIG. 10 is a diagram showing diffused light irradiated onto an irradiation surface when light is incident on a boundary region of an optical element according to Example 1 at a first surface incident angle of 10 degrees. FIG. 10 is a diagram showing diffused light irradiated onto an irradiation surface when light is incident on a boundary region of the optical element according to Example 1 at a first surface incident angle of 20 degrees. FIG. 10 is a diagram showing diffused light irradiated onto an irradiation surface when light is incident on a boundary region of the optical element according to Example 1 at a first surface incident angle of 30 degrees. FIG. FIG. 10 is a schematic perspective view of a light source device according to a second embodiment. 10A and 10B are diagrams illustrating a first example of diffused light emitted from a light source device according to a second embodiment. 10A and 10B are diagrams illustrating a second example of diffused light emitted from the light source device according to the second embodiment. 10A and 10B are diagrams illustrating a third example of diffused light emitted from the light source device according to the second embodiment. 10A and 10B are diagrams showing a first example of an intensity profile of diffused light emitted from a light source device according to a second embodiment. 10A and 10B are diagrams showing a second example of the intensity profile of diffused light emitted from the light source device according to the second embodiment.

Below, embodiments for implementing the present disclosure will be described in detail with reference to the drawings. However, the embodiments shown below are examples of optical elements that embody the technical concepts of the present disclosure, and are not limited to the following. Note that the size, positional relationships, etc. of components shown in each drawing may be exaggerated for clarity. In each drawing, identical components are designated by the same reference numerals, and duplicate explanations will be omitted where appropriate.

In the drawings shown below, directions may be represented using a Cartesian coordinate system having an X-axis, a Y-axis, and a Z-axis. The X-direction along the X-axis indicates a specific direction within the plane of the first surface of the optical element according to the embodiment. The Y-direction along the Y-axis indicates a direction perpendicular to the X-direction within the plane of the first surface. The Z-direction along the Z-axis indicates a direction perpendicular to the first surface.

The direction in which the arrow points in the X direction is referred to as the +X direction, and the direction opposite to the +X direction is referred to as the -X direction. The direction in which the arrow points in the Y direction is referred to as the +Y direction, and the direction opposite to the +Y direction is referred to as the -Y direction. The direction in which the arrow points in the Z direction is referred to as the +Z direction, and the direction opposite to the +Z direction is referred to as the -Z direction. In the embodiment, light traveling in the +Z direction is incident on the optical element and emitted from the optical element. In this specification, a top view refers to viewing the optical element of the embodiment in the direction in which the light travels, i.e., the +Z direction. However, these directional expressions do not limit the directions in the embodiments of the present disclosure.

In this specification and claims, "substantially parallel" means that the absolute value of the angular deviation from the parallel state is between 0 and 10 degrees. Furthermore, "substantially perpendicular" means that the absolute value of the angular deviation from the perpendicular state is between 0 and 10 degrees.

[First embodiment]
<Configuration of Optical Element According to First Embodiment>
The overall configuration of an optical element according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic top view showing an example of the overall configuration of an optical element 100 according to the first embodiment. Figure 2 is a schematic cross-sectional view of the optical element 100 taken along line II-II in Figure 1.

As shown in FIG. 2, the optical element 100 has a substrate 1 including a first surface 1a and a second surface 1b located opposite the first surface 1a. As shown in FIGS. 1 and 2, the substrate 1 includes an optical region 10 in which optical elements 11-1 to 11-4 are arranged in a portion of the first surface 1a. The substrate 1 also includes a peripheral region 12, which is provided around the optical region 10 on the surface of the substrate 1 where the optical region 10 is provided, and in which no optical elements 11 are arranged. The optical elements 11 are lens elements. In the example shown in FIG. 2, a first anti-reflection film 13a is provided on the surface of the optical region 10 and the peripheral region 12 on the first surface 1a of the substrate 1. Furthermore, a second anti-reflection film 13b is provided on the surface of the second surface 1b of the substrate 1.

In FIG. 2, in a cross section including the optical axis 11C-1 of optical element 11-1, which is closest to peripheral region 12 among optical elements 11-1 to 11-4, boundary region 110 is defined as the cross-sectional region from vertex 11T-1 of optical element 11-1, through which optical axis 11C-1 passes, to end 12E in peripheral region 12 closest to optical element 11-1. In this embodiment, the average absolute value of the surface inclination a in boundary region 110 is 1.00 or less, and the variation σ is 0.10 or greater. σ represents the standard deviation. Optical axis 11C-1 refers to the axis that passes through the center of optical element 11-1 and is aligned with the traveling direction of light. In the example shown in FIG. 2, the traveling direction of light is along the Z axis. Vertex 11T-1 and end 12E are not included in boundary region 110.

In the example shown in Figure 2, the first surface 1a corresponds to the incident surface where light is incident, and the second surface 1b corresponds to the exit surface where light incident from the incident surface is emitted after passing through the interior of the substrate 1. The optical element 100 shown in Figure 2 diffuses light incident from the first surface 1a in the optical region 10, and emits diffused light with low directionality from the second surface 1b.

In Figures 1 and 2, optical element 11 is a generic notation when optical elements 11-1 to 11-4 are not distinguished from one another. In the example shown in Figures 1 and 2, the reference numeral for optical element 11 is written alongside the reference numerals for optical elements 11-1 to 11-4 to indicate that optical element 11 is a generic notation for optical elements 11-1 to 11-4.

Here, for example, in the optical element described in Patent Document 1, the boundary region between the optical region and the peripheral region is formed by a plane that is approximately perpendicular to the second surface on the side from which light is emitted from the optical element. In the optical element described in Patent Document 1, the boundary region is a plane with an infinite slope, since the boundary region is a plane that is approximately perpendicular to the second surface. In an optical element including a boundary region that is a plane with an infinite slope, light that enters the boundary region passes through the interior of the substrate of the optical element and is then totally reflected by the second surface on the side from which light is emitted, resulting in an increase in the amount of light that returns in the direction of incidence. This increase in returned light reduces the light extraction efficiency of the diffused light that is emitted from the optical element. Furthermore, in an optical element including a boundary region that is a plane with an infinite slope, light that enters the boundary region between the optical region and the peripheral region may be locally concentrated, resulting in light with locally high luminous intensity being emitted from the optical element. Light with locally high luminous intensity may be undesirable from the perspective of eye safety, which aims to reduce harm to the human eyes.

In the optical element 100 of this embodiment, the surface inclination a in the boundary region 110 has an average absolute value of 1.00 or less and a variation σ of 0.10 or more. For example, the surface in the boundary region 110 is a smoothly curved surface that satisfies the conditions that the average absolute value is 1.00 or less and the variation σ is 0.10 or more. By satisfying this condition, the surface inclination a in the boundary region 110 is no longer uniform, and light incident on the boundary region 110 is refracted at various refraction angles. Because the light incident on the boundary region 110 is refracted at various refraction angles, light that has passed through the interior of the substrate 1 is incident on the second surface 1b at various angles, thereby reducing the light that is totally reflected at the second surface 1b and reducing the light that returns in the direction of incidence. By reducing the returned light, the light extraction efficiency of the diffused light emitted from the optical element 100 is increased. Furthermore, in the optical element 100, light incident on the boundary region 110 is refracted at various refraction angles, thereby reducing localized concentration of light incident on the boundary region 110 and emitted from the optical element 100, and reducing light with locally high luminous intensity emitted from the optical element 100. As described above, this embodiment increases the light extraction efficiency of diffused light and reduces light with locally high luminous intensity. Furthermore, by reducing light with locally high luminous intensity, an optical element 100 with high safety from the perspective of eye safety can be provided. In particular, when light incident on the optical element is light that tends to be highly luminous, such as laser light, reducing light with locally high luminous intensity can achieve significant effects from the perspective of eye safety.

The average absolute value of the surface inclination a in the boundary region 110 is preferably 0.90 or less, more preferably 0.80 or less, and even more preferably 0.70 or less. From the perspective of increasing the diffusion angle γ, the average absolute value of the inclination a is preferably 0.2 or more, and even more preferably 0.3 or more. The variation σ is preferably 0.20 or more, more preferably 0.30 or more, and even more preferably 0.40 or more.

In the optical element 100, a peripheral region 12 is provided around the optical region 10. This allows a bonding material to be applied to the peripheral region 12 when bonding the optical element 100 to another member, reducing the infiltration of part of the optical region 10 with the bonding material. By reducing the area that is infiltrated by the bonding material and does not provide the desired optical properties, the optical region 10 can be used more effectively.

Furthermore, by providing the peripheral region 12 around the optical region 10, chipping and other defects can be prevented from occurring in the optical region 10 when multiple optical elements 100 are formed on a single substrate and the substrate is cut to obtain a large number of optical elements 100. Preventing chipping and other defects improves the quality of each of the multiple optical elements 100 obtained, and prevents a decrease in the mechanical strength of the optical region 10 due to defects in the optical region 10.

In the optical element 100 shown in FIGS. 1 and 2, the optical region 10 is recessed relative to the peripheral region 12 in the substrate 1. The optical element 11 shown in FIGS. 1 and 2 has a concave surface recessed relative to the peripheral region 12. Because the optical region 10 is recessed relative to the peripheral region 12, when the optical element 100 comes into contact with other components, the peripheral region 12 comes into contact with the other components preferentially. This reduces contact of the optical element 11 placed in the optical region 10 with other components, thereby reducing damage to the optical element 11 due to contact or friction with other components. However, the optical element 11 is not limited to being concave, and may be convex. Furthermore, the apex of the convex surface is not limited to being located lower than the peripheral region 12 in the direction along the optical axis 11C-1, and may be located higher.

In the example shown in Figures 1 and 2, the optical region 10 includes a plurality of optical elements 11, which are arranged two-dimensionally without exposing any flat surfaces. By not exposing any flat surfaces, the optical element 100 can reduce high-intensity light that passes through the flat surfaces and travels straight ahead. This makes it possible to provide an optical element 100 that is highly safe from an eye-safe perspective.

In the example shown in Figures 1 and 2, the distance Ds connecting the vertices 11T-1 and 11T-2 of adjacent optical elements 11-1 and 11-2 among the multiple optical elements 11 is 10 μm or more and 200 μm or less. By setting the distance Ds to 10 μm or more, it is easier to process adjacent optical elements 11-1 and 11-2 compared to when the distance Ds is less than 10 μm, thereby facilitating the manufacture of optical element 100. Furthermore, by setting the distance Ds to 200 μm or less, the amount of processing required for each of optical elements 11-1 and 11-2 to connect the ends of optical element 11-1 and 11-2 can be reduced compared to when the distance Ds is greater than 200 μm. By reducing the amount of processing required for each of optical elements 11-1 and 11-2, the manufacturing efficiency of optical element 100 can be improved. Furthermore, by reducing the amount of processing required for each of optical elements 11-1 and 11-2, it is possible to prevent the thickness of optical element 100, i.e., the length of optical element 100 in the Z direction, from becoming thin, thereby increasing the mechanical strength of optical element 100.

In the example shown in FIG. 2, the depth Dp between the vertex 11T-1 of the optical element 11-1 and the end 12E of the peripheral region 12 in the direction along the optical axis 11C-1 is 3 μm or more and 100 μm or less. Setting the depth Dp to 3 μm or more makes it easier to process the optical element 11-1 compared to when the depth Dp is less than 3 μm, thereby facilitating the manufacture of the optical element 100. Furthermore, setting the depth Dp to 100 μm or less reduces the amount of processing required for the optical element 11-1 compared to when the depth Dp is greater than 100 μm. Reducing the amount of processing required for the optical element 11-1 increases the manufacturing efficiency of the optical element 100. Furthermore, reducing the amount of processing required for the optical element 11-1 prevents the optical element 100 from becoming thinner, thereby increasing the mechanical strength of the optical element 100. While the above example describes the optical element 11-1, similar effects can be achieved with other optical elements 11.

The substrate 1 can be made of a material including a glass material or a resin material. The glass material or resin material used for the substrate 1 can be selected appropriately depending on the intended use of the optical element 100. The optical elements 11 can be formed on the substrate 1 using an etching method, a molding method, or the like, and placed in the optical region 10.

The substrate 1 may include an optical region 10 on at least one of the first surface 1a and the second surface 1b. The optical region 10 is not limited to four optical elements 11-1 to 11-4, but may include at least one optical element 11. A cross section including the optical axis 11C of the optical element 11-1 closest to the peripheral region 12 may be any cross section of the optical element 100, as long as it includes the optical axis 11C of the optical element 11-1 closest to the peripheral region 12. The incident surface is not limited to the first surface 1a, but may be the second surface 1b. The exit surface is not limited to the second surface 1b, but may be the first surface 1a.

The first anti-reflection film 13a reduces light reflected from the first surface 1a of the substrate 1. The second anti-reflection film 13b reduces light reflected from the second surface 1b of the substrate 1. The first anti-reflection film 13a and the second anti-reflection film 13b can each be constructed to include a dielectric film material such as magnesium fluoride. However, the optical element 100 does not necessarily have to include the first anti-reflection film 13a and the second anti-reflection film 13b.

<Relationship between the surface inclination a and the diffusion angle γ in the boundary region 110>
3 is a schematic diagram showing an example of the relationship between the inclination a of the surface in the boundary region 110 of the optical element 100 and the diffusion angle γ. FIG. 3 is an enlarged view of the optical element 11-1 in FIG. 2. In FIG. 3, the light L indicated by the thick line represents a light ray incident on the boundary region 110 of the optical element 11-1. In the example shown in FIG. 3, the light L incident on the boundary region 110 from a direction perpendicular to a plane parallel to the second surface 1b is refracted at the surface of the boundary region 110, passes through the inside of the base material 1, and then is emitted from the second surface 1b of the optical element 100.

In the example shown in FIG. 3, the inclination a represents the inclination of the surface at position Po1 in the boundary region 110 where light L is incident. The inclination angle a' represents the angle of the inclination of the surface at position Po1 in the boundary region 110 with respect to a plane parallel to the second surface 1b. The normal angle θ represents the angle of the normal (-1/a) to the surface at position Po1 in the boundary region 110 with respect to a plane parallel to the second surface 1b. The refraction angle β represents the angle of light L with respect to the normal (-1/a) to the surface at position Po1 in the boundary region 110. The second surface incident angle ε represents the angle of light L, which enters the interior of the base material 1 through position Po1, passes through the interior of the base material 1, and then enters position Po2 on the second surface 1b, with respect to the normal to the second surface 1b. The diffusion angle γ represents the angle of light L, which exits position Po2 on the second surface 1b, with respect to the normal to the second surface 1b.

The normal angle θ is expressed by the following equation (1):

The refraction angle β is expressed by the following formula (2), where n is the refractive index of the substrate 1 and π is the constant of the circumference of a circle.

The second surface incident angle ε is expressed by the following equation (3):

The diffusion angle γ is expressed by the following equation (4):

Table 1 shows the correspondence between the tilt a, tilt angle a', normal angle θ, refraction angle β, second surface incident angle ε, and diffusion angle γ obtained using the above equations (1) to (4) when the refractive index n of substrate 1 is 1.52.

When the refractive index n of the substrate 1 is 1.52, the critical angle is 41.14 degrees. Therefore, if the second surface incident angle ε is less than 41.14 degrees, light L that passes through the interior of the substrate 1 and is incident on the second surface 1b is refracted at the second surface 1b and emitted from the second surface 1b. On the other hand, if the second surface incident angle ε is 41.14 degrees or greater, light L is totally reflected by the second surface 1b.

In an optical element 100 in which multiple optical elements 11 are arranged, light incident on an optical element 11 arranged on the first surface 1a may be refracted by the optical element 11 and then incident on an adjacent optical element 11. Considering the case where light incident on an optical element 11 also enters an adjacent optical element 11, if the light is incident on the optical element 11 from a direction perpendicular to a plane parallel to the second surface 1b, it is preferable that the second surface incident angle ε is 27.4 degrees or less and the slope a is 2.0 degrees or less. A slope a of 2.0 or less corresponds to a slope angle a' of 63.4 degrees or less. Furthermore, considering the case where light is incident on an adjacent optical element 11, if the light is incident on the optical element 11 from a direction intersecting the plane parallel to the second surface 1b, it is preferable that the refraction angle β is 36.0 degrees or less. By satisfying the above conditions, the optical element 100 can reduce the amount of returned light caused by total reflection at the second surface 1b and increase the light extraction efficiency of the diffused light emitted from the optical element 100.

Furthermore, the diffusion angle γ is uniquely determined by the surface inclination a in the boundary region 110, regardless of the direction of light incident on the boundary region 110. If the surface inclination a in the boundary region 110 were approximately constant regardless of position, the light emitted from the optical element 100 would be locally concentrated, and light with locally high luminous intensity would be more likely to be included in the diffused light. In contrast, in the optical element 100, by changing the surface inclination a in the boundary region 110 depending on the position, it is possible to reduce the local concentration of light emitted from the optical element 100 and reduce light with locally high luminous intensity.

For optical element 100, it is preferable that the FWHM be 20 degrees or greater when parallel light with an emission peak wavelength of 300 nm or greater and 1000 nm or less is incident. By satisfying this condition, the diffused light emitted from optical element 100 can be spread and irradiated onto the irradiation surface. Note that FWHM (full width at half maximum m) refers to the maximum angular region enclosed by an intensity of 0.5 when the average intensity in the diffusion angle range of -10° to +10° is normalized to 1 in the one-dimensional direction in which the distance of the two-dimensional image projected onto a plane parallel to the surface of the element is at its maximum, and the relative intensity is plotted as a function of the diffusion angle.

By setting the FWHM to 20 degrees or more when parallel light with an emission peak wavelength of 300 nm or more and 1000 nm or less is incident, the following effects can be achieved when incorporating optical element 100 into a device: (1) When incorporating optical element 100 into a projector, the device can be made more compact. (2) When incorporating optical element 100 into a sensing device, information from a wider field of view can be captured at once. (3) When incorporating optical element 100 into a lighting device, the illumination range over a short distance can be expanded.

When parallel light with an emission peak wavelength of 300 nm or more and 1000 nm or less is incident on the optical element 100, the total light transmittance of the diffused light is preferably 93% or more. By satisfying this condition, the diffused light emitted from the optical element 100 can be made brighter.

When parallel light having an emission peak wavelength of 300 nm or more and 1000 nm or less is incident, the total light transmittance of the diffused light emitted from the optical element 100 can be set to 93% or more, thereby reducing the attenuation of light that passes through the optical element 100. This makes it possible to reduce the power consumption of devices such as projectors and sensing devices when the optical element 100 is incorporated into such devices. Furthermore, when the optical element 100 is incorporated into a lighting device, it can provide brighter illumination with the same amount of power.

Next, the area ratio between the substrate 1 and the optical region 10 in the optical element 100 will be described with reference to Figures 4 and 5. Figure 4 is a diagram showing an example of the area ratio between the substrate 1 and the optical region 10 in the optical element 100. Figure 5 is a diagram showing another example of the area ratio between the substrate 1 and the optical region 10 in the optical element 100.

In the optical element 100 shown in FIG. 4, the substrate 1 has a substantially rectangular outer edge shape when viewed from above. The optical region 10 also has a substantially rectangular outer edge shape when viewed from above. The width of the substrate 1 in the X direction is b, the width of the optical region 10 in the X direction is b x (1 - P), the width of the substrate 1 in the Y direction is c, and the width of the optical region 10 in the Y direction is c(1 - Q). Note that P satisfies 0 < P < 1, and Q satisfies 0 < Q < 1. In this case, the area ratio of the optical region 10 to the area of the substrate 1 can be expressed as 1 - P - Q + P x Q.

Table 2 shows the correspondence between P, Q, and the area ratio of the optical region 10 to the area of the substrate 1.

In the optical element 100 shown in Fig. 5, the substrate 1 has a substantially circular outer edge shape in top view. The optical zone 10 also has a substantially circular outer edge shape in top view. The radius of the substrate 1 is d, and the radius of the optical zone 10 is d x (1 - R), where R satisfies 0 < R < 1. In this case, the ratio of the area of the optical zone 10 to the area of the substrate 1 can be expressed as 1 - 2 x R + ^R2 .

Table 3 shows the correspondence between R and the area ratio of the optical region 10 to the area of the substrate 1.

In the optical element 100 shown in each of Figures 4 and 5, it is preferable that the area ratio of the optical region 10 to the area of the substrate 1 be 0.0625 or more and 0.9025 or less. For example, if the area of the optical region 10 is too large relative to the area of the substrate 1, when bonding the optical element 100 to another component, the area on the substrate 1 to which the bonding material is applied will be narrow, and good bonding strength may not be obtained. In the optical element 100, by setting the area ratio of the optical region 10 to the area of the substrate 1 to 0.9025 or less, good bonding strength can be obtained when bonding the optical element 100 to another component. On the other hand, if the area of the optical region 10 is too small relative to the area of the substrate 1, it will be difficult for light to enter the optical region 10, and the desired optical characteristics may not be obtained in the diffused light emitted from the optical element 100. In the optical element 100, by setting the area ratio of the optical region 10 to the area of the substrate 1 to 0.0625 or greater, it is possible to obtain the desired optical characteristics in the diffused light emitted from the optical element 100.

Examples and Comparative Examples
Examples and comparative examples will be described below, but the present disclosure is not limited to these examples. Examples 1 and 2 shown below are examples, and Example 3 is a comparative example.

(Example 1)
In Example 1, the optical element 100 shown in the following FIGS. 6 to 10 was fabricated, and the optical element 100 was evaluated based on the results of measurements using a confocal microscope. The substrate 1 used had a refractive index of 1.52. In the optical element 100 shown in FIGS. 6 to 10, of the multiple optical elements 11, each of which is a lens element, the center-to-center distance between adjacent optical elements 11 is, for example, 40.0±1.0 μm. Furthermore, in the optical element 100 shown in FIGS. 6 to 10, the depth Dp of the optical elements 11 is 10.0±2.0 μm.

Figure 6 is a top view photograph showing the optical element 100 according to Example 1. Figure 7 is a diagram showing the cross-sectional shape of the optical element 100 taken along line VII-VII in Figure 6. Figure 8 is an enlarged view of region VIII in Figure 7. Figure 9 is a diagram showing the first derivative of Figure 8. Figure 10 is a diagram showing the probability density of the diffusion angle in region VIII in Figure 7.

Figure 6 shows a photograph of the optical region 10 of the optical element 100 according to Example 1 taken from above using a confocal microscope. Figure 7 shows the results of measuring the cross-sectional shape of the optical element 100 taken along line VII-VII in Figure 6 using a confocal microscope. Figure 8 shows the cross-sectional shape of region VIII in Figure 7, i.e., the boundary region 110 in Figure 6. The first derivative dZ/dX in Figure 9 shows the calculation results for the slope a at each position in the cross-sectional shape of the boundary region 110 in Figure 8. Figure 10 shows the calculation results for the probability density of the diffusion angle γ when light incident on the boundary region 110 shown in Figures 7 to 9 is emitted from the optical element 100.

As shown in Figures 7 to 9, the boundary region 110 shown in Figure 6 has a smoothly curved, concave, aspherical shape. In the boundary region 110 shown in Figure 6, the first derivative dZ/dX gradually changes depending on the position X, as shown in Figure 9. In other words, the surface slope a gradually changes in the boundary region 110 shown in Figure 6. In the boundary region 110 shown in Figure 6, the surface slope a is not constant, so the refraction angle β of light incident on the boundary region 110 is not constant. Because the refraction angle β is not constant, the diffusion angle γ varies, as shown in Figure 10. As a result, the optical element of Example 1 can reduce local concentration of light emitted from the optical element 100 and reduce light with locally high luminous intensity.

Table 4 shows the average, maximum, minimum, and standard deviation of the tilt a and the diffusion angle γ for the optical element 100 of Example 1.

As shown in Table 4, in the optical element 100 of Example 1, the average absolute value of the slope a in the boundary region 110 was 0.54, and the variation σ of the slope a was 0.36. Therefore, Example 1 satisfies the above-mentioned condition that "the average absolute value of the slope a in the boundary region 110 is 1.00 or less, and the variation σ of the slope a is 0.10 or more."

(Example 2)
In Example 2, the optical element 100 shown in the following FIGS. 11 to 15 was fabricated, and the optical element 100 was evaluated based on the results of measurements using a confocal microscope. The substrate 1 used had a refractive index of 1.52. In the optical element 100 shown in FIGS. 11 to 15, of the multiple optical elements 11, each of which is a lens element, the center-to-center distance between adjacent optical elements 11 is, for example, 22.5±2.5 μm. Furthermore, in the optical element 100 shown in FIGS. 11 to 15, the depth Dp of the optical elements 11 is 5.0±2.0 μm.

Figure 11 is a top view photograph showing the optical element 100 according to Example 2. Figure 12 is a diagram showing the cross-sectional shape of the optical element 100 taken along line XII-XII in Figure 11. Figure 13 is an enlarged view of region XIII in Figure 12. Figure 14 is a diagram showing the first derivative of Figure 13. Figure 15 is a diagram showing the probability density of the diffusion angle in region XIII in Figure 12.

The substrate 1 of the optical element 100 according to Example 2 had a refractive index of 1.52. Figure 11 shows a photograph of the optical region 10 of the optical element 100 according to Example 2 taken from above using a confocal microscope. Figure 12 shows the results of measuring the cross-sectional shape of the optical element 100 taken along line XII-XII in Figure 11 using a confocal microscope. Figure 13 shows the cross-sectional shape of region XIII in Figure 12, i.e., the boundary region 110 in Figure 11. The first-order differential dZ/dX in Figure 14 shows the calculation results for the slope a at each position in the cross-sectional shape of the boundary region 110 in Figure 13. Figure 15 shows the calculation results for the probability density of the diffusion angle γ when light incident on the boundary region 110 shown in Figures 11 to 14 is emitted from the optical element 100.

As shown in Figures 12 to 14, the boundary region 110 shown in Figure 11 has a substantially linear inclined surface. However, as shown in Figure 14, the boundary region 110 shown in Figure 11 has a first derivative dZ/dX that changes periodically depending on the position X microscopically. Also, as shown in Figure 11, the boundary region 110 includes a shape that is periodic microscopically. In the boundary region 110 shown in Figure 11, the inclination a of the surface is not constant microscopically, so the refraction angle β of light incident on the boundary region 110 is not constant. Because the refraction angle β is not constant, the diffusion angle γ varies, as shown in Figure 15. As a result, the optical element 100 of Example 2 can reduce local concentration of light emitted from the optical element 100 and reduce light with locally high luminous intensity.

As shown in Figures 11 and 14, in the optical element 100 of the second example, the boundary region 110 includes a shape in which the surface height Z changes periodically depending on the position X. Because the boundary region 110 includes a shape in which the surface height Z changes periodically depending on the position X, the probability density of the diffusion angle γ approaches a normal distribution, as shown in Figure 15. Because the probability density of the diffusion angle γ approaches a normal distribution, in the optical element 100 of the second example, the shape in which the height Z changes periodically depending on the position X acts as a light diffusion surface. As a result, in the optical element 100 of the second example, the diffusion effect on light incident on the boundary region 110 can be enhanced.

Table 5 shows the average, maximum, minimum, and standard deviation of the tilt a and the diffusion angle γ for the optical element 100 of Example 2.

As shown in Table 5, in the optical element 100 of Example 2, the average absolute value of the slope a in the boundary region 110 was 0.68, and the variation σ of the slope a was 0.62. Therefore, Example 2 satisfies the above-mentioned condition that "the average absolute value of the slope a in the boundary region 110 is 1.00 or less, and the variation σ of the slope a is 0.10 or more."

(Example 3)
In Example 3, the optical element 100X was evaluated by ray tracing simulation. Zemax OpticStudio 18.4.1 was used for the ray tracing simulation. The refractive index of the substrate 1X in the optical element 100X was set to 1.52. Other specifications of the optical element 100X were mainly those of the optical element described in Patent Document 1.

16 to 20, an optical element 100X according to Example 3 will be described. FIG. 16 is a perspective view showing the behavior of light Li incident on boundary region 110X of optical element 100X according to Example 3. FIG. 17 is a side view showing the behavior of light Li incident on boundary region 110X of optical element 100X according to Example 3. FIG. 18 is a diagram showing light Lt irradiated onto the irradiation surface S when light Li is incident on boundary region 110X of optical element 100X according to Example 3 at a first surface incident angle α of 10 degrees. FIG. 19 is a diagram showing light Lt irradiated onto the irradiation surface S when light Li is incident on boundary region 110X of optical element 100X according to Example 3 at a first surface incident angle α of 20 degrees. FIG. 20 is a diagram showing light Lt irradiated onto the irradiation surface S when light Li is incident on boundary region 110X of optical element 100X according to Example 3 at a first surface incident angle α of 30 degrees.

As shown in FIG. 17, the optical element 100X of the third example has a substrate 1X including a first surface 1aX and a second surface 1bX located opposite the first surface 1aX. The substrate 1X includes an optical region 10X in which an optical element 11X is arranged in a part of the first surface 1aX. The substrate 1X also includes a peripheral region 12X on the surface of the substrate 1X on which the optical region 10X is arranged, which is arranged around the optical region 10X and in which no optical element 11X is arranged. The optical element 11X included in the optical region 10X is a lens element. The optical region 10X includes a boundary region 110X defined in the same manner as the boundary region 110 described above. In the optical element 100X, the boundary region 110X is a plane that is approximately perpendicular to the second surface 1bX. In the optical element 100X, the boundary region 110X is a plane that is approximately perpendicular to the second surface 1bX, and the boundary region 110X is a plane with an infinite slope a.

17, light Li incident on boundary region 110X at a first surface incident angle α is refracted at boundary region 110X, passes through the interior of substrate 1X in optical element 100X, and much of it is totally reflected at second surface 1bX. Return light Lr reflected at second surface 1bX is returned to the side of optical element 100X from which light Li entered. In optical element 100X including boundary region 110X which is a plane with an infinite slope a, light Li incident on boundary region 110X is likely to be totally reflected at second surface 1bX. As a result, the amount of return light Lr increases, and as shown in Figures 18 to 20, less light Lt reaches the irradiation surface S. The light extraction efficiency from optical element 100X is 67.2% in the example shown in Figure 18, 44.7% in the example shown in Figure 19, and 0.19% in the example shown in Figure 20. Furthermore, the light Lt shown in Figures 18 and 19 is light with a locally high luminous intensity that is generated by the local concentration of light incident on the boundary region between the optical region and the peripheral region.

As described above, in optical element 100X, there is a large amount of returned light due to total reflection, and the light extraction efficiency of the diffused light emitted from optical element 100X decreases. In optical element 100X, light incident on the boundary region between the optical region and the peripheral region is locally concentrated, causing light with locally high luminous intensity to be emitted from the optical element.

(Evaluation Results of the Optical Element 100 According to Example 1 by Simulation)
The optical element 100 according to Example 1 was evaluated by ray tracing simulation. Zemax OpticStudio 18.4.1 was used for the ray tracing simulation.

21 to 25, the evaluation results of the simulation of the optical element 100 according to Example 1 will be described. FIG. 21 is a perspective view showing the behavior of light Li incident on the boundary region 110 of the optical element 100 according to Example 1. FIG. 22 is a side view showing the behavior of light Li incident on the boundary region 110 of the optical element 100 according to Example 1. FIG. 23 is a diagram showing diffused light Ls irradiated onto the irradiation surface S when light Li is incident on the boundary region 110 of the optical element 100 according to Example 1 at a first surface incident angle α of 10 degrees. FIG. 24 is a diagram showing diffused light Ls irradiated onto the irradiation surface S when light Li is incident on the boundary region 110 of the optical element 100 according to Example 1 at a first surface incident angle α of 20 degrees. FIG. 25 is a diagram showing diffused light Ls irradiated onto the irradiation surface S when light Li is incident on the boundary region 110 of the optical element 100 according to Example 1 at a first surface incident angle α of 30 degrees.

As shown in FIG. 22, light Li incident on boundary region 110 at a first surface incident angle α is refracted at boundary region 110, passes through the interior of substrate 1 in optical element 100, and then much of the light is emitted through second surface 1b without being totally reflected at second surface 1b. Reducing total reflection at second surface 1b reduces the amount of returning light, and as shown in FIGS. 23 to 25, more diffused light Ls reaches the irradiation surface S. The light extraction efficiency from optical element 100 is 96.1% in the example shown in FIG. 23, 96.3% in the example shown in FIG. 24, and 96.6% in the example shown in FIG. 20. Furthermore, the diffused light Ls shown in FIGS. 23 to 25 spreads after being emitted from optical element 100 and then irradiates the irradiation surface S. Diffused light Ls does not include light with locally high luminous intensity.

As described above, the optical element 100 according to Example 1 can increase the light extraction efficiency of diffused light emitted from the optical element 100 and reduce light with locally high luminous intensity. While the examples shown in Figures 21 to 25 show the optical element 100 according to Example 1, similar results can also be obtained with the optical element 100 according to Example 2.

Second Embodiment
A light source device 200 according to the second embodiment will be described. Note that the same names and symbols as those in the already described embodiments indicate the same or similar members or configurations, and detailed descriptions thereof will be omitted as appropriate.

FIG. 26 is a schematic perspective view showing an example of a light source device 200 according to the second embodiment. As shown in FIG. 26, the light source device 200 has a light source 150 and an optical element 100 arranged on the emission side of the light source 150. The optical element 100 diffuses light L0 from the light source 150. The light source device 200 emits diffused light Ls by the optical element 100. In the example shown in FIG. 26, the light source device 200 emits diffused light Ls whose outer edge has a substantially rectangular shape with a longitudinal direction when viewed in the +Z direction.

In this embodiment, the light source device 200 includes the optical element 100, which increases the light extraction efficiency of the diffused light Ls emitted from the light source device 200 and reduces light with locally high luminous intensity.

In the light source device 200 shown in FIG. 26, the optical element 100 is arranged with the first surface 1a, on which the optical region 10 is arranged, facing the light source 150. The light source device 200 is used for sensing or lighting applications. In sensing applications, for example, in LiDAR (Light Detection and Ranging), the light source device 200 can be used as a light projecting device that projects diffused light for measurement into a measurement range. In lighting applications, for example, in a projection device such as a projector, the light source device 200 can be used as an illumination device that illuminates a spatial modulator such as a liquid crystal panel with diffused light. The light source device 200 can increase the light extraction efficiency of the diffused light Ls emitted from the light source device 200 and reduce light with locally high luminous intensity. Therefore, using the light source device 200 for sensing applications can improve the accuracy of sensing devices such as LiDAR. Furthermore, by using the light source device 200 for lighting purposes, the quality of images projected by a projection device such as a projector can be improved.

A semiconductor laser can be used as the light source 150. However, the light source 150 is not limited to a semiconductor laser, and laser light sources other than semiconductor lasers, such as solid-state lasers, and light sources other than laser light sources, such as light-emitting diodes, can also be used. The emission peak wavelength of the light emitted from the light source 150 can be selected appropriately depending on the application of the light source device 200.

The outer edge shape of the diffused light Ls when viewed in the +Z direction follows the outer edge shape of the optical elements 11 arranged in the optical region 10 of the optical element 100 when viewed in the +Z direction. The light source device 200 can emit diffused light Ls with various outer edge shapes depending on the outer edge shape of the optical elements 11 when viewed in the +Z direction. Figure 27 is a diagram showing a first example of diffused light Ls emitted from the light source device 200. Figure 28 is a diagram showing a second example of diffused light Ls emitted from the light source device 200. Figure 29 is a diagram showing a third example of diffused light Ls emitted from the light source device 200.

The first example shown in Figure 27 shows diffused light Ls whose outer edge shape when viewed in the +Z direction is approximately square. The second example shown in Figure 28 shows diffused light Ls whose outer edge shape when viewed in the +Z direction is approximately rectangular with the X direction as its longitudinal axis. The third example shown in Figure 29 shows diffused light Ls whose outer edge shape when viewed in the +Z direction is approximately regular hexagonal. In addition to these, the light source device 200 can emit diffused light Ls whose outer edge shape is approximately circular, approximately elliptical, approximately polygonal, etc., depending on the outer edge shape of the optical element 11 when viewed in the +Z direction.

Figures 30 and 31 are diagrams showing the intensity profile of diffused light Ls emitted from light source device 200. The intensity profile of diffused light Ls refers to a collection of intensity values obtained from points spaced equally along a line segment path that is approximately perpendicular to the direction of travel of diffused light Ls. In Figures 30 and 31, the horizontal axis represents angle and the vertical axis represents intensity. Figure 30 shows the intensity profile of flat-top diffused light Ls. Figure 31 shows the intensity profile of 1/cosθ diffused light Ls. The intensity profile of diffused light Ls can be determined appropriately depending on the shape or arrangement of the optical element 11, etc.

Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

All ordinal numbers, quantitative numbers, and other figures used in the description of the embodiments are provided as examples to specifically explain the technology of the present disclosure, and the present disclosure is not limited to the illustrated figures. Furthermore, the interconnections between components are provided as examples to specifically explain the technology of the present disclosure, and do not limit the interconnections that realize the functions of the present disclosure.

The optical element and light source device according to the present disclosure can increase the light extraction efficiency of diffused light emitted from the optical element and reduce light with locally high luminous intensity, making it suitable for use in projection devices such as projectors, sensing devices such as LiDAR, and the like. However, the optical element and light source device according to the embodiment are not limited to these, and can be applied to a variety of fields that use optical techniques.

This application claims priority based on Japanese Patent Application No. 2024-17281, filed February 7, 2024, the disclosure of which is incorporated herein in its entirety.

1 Substrate 1a First surface 1b Second surface 10 Optical region 11, 11-1 to 11-4 Optical element 11C-1, 11C-2 Optical axis 11T-1, 11T-2 Vertex 110 Boundary region 12 Peripheral region 12E End 13a First anti-reflection film 13b Second anti-reflection film 100 Optical element 150 Light source 200 Light source device a Inclination a' Inclination angle b Width of substrate in X direction c Width of substrate in Y direction d Radius Dp Depth Ds Distance Li Incident light Lr Return light Ls Diffused light Lt Light Po1, Po2 Position S Irradiation surface α First surface incident angle β Refraction angle ε Second surface incident angle θ Normal angle

Claims (10)

a substrate including a first surface and a second surface opposite the first surface;
The substrate is
an optical region in which at least one optical element is arranged on a part of at least one of the first surface and the second surface;
a peripheral region on the surface of the base material on which the optical region is provided, the peripheral region being provided around the optical region and in which the optical element is not disposed;
the optical element is a lens element;
In a cross section including the optical axis of the optical element closest to the peripheral region among at least one of the optical elements, a cross-sectional area from the vertex of the optical element through which the optical axis passes to an end of the peripheral region closest to the optical element is defined as a boundary region.
An optical element, wherein the average absolute value of the surface inclination in the boundary region is 1.00 or less and the variation σ is 0.10 or more. The optical element of claim 1, wherein the optical region is recessed relative to the peripheral region in the substrate. the optical region includes a plurality of the optical elements;
3. The optical element according to claim 1, wherein the plurality of optical elements are arranged two-dimensionally without exposing any flat surface. The optical element described in claim 1 or claim 2, wherein the area ratio of the optical region to the area of the substrate is 0.0625 or more and 0.9025 or less. The optical element described in claim 3, wherein the distance between the vertices of adjacent optical elements among the plurality of optical elements is 10 μm or more and 200 μm or less. An optical element according to claim 1 or 2, wherein the depth in the direction along the optical axis between the vertex of the optical element and the edge of the peripheral region is 3 μm or more and 100 μm or less. The optical element described in claim 1 or 2, wherein the FWHM when parallel light having an emission peak wavelength of 300 nm or more and 1000 nm or less is incident is 20 degrees or more. The optical element described in claim 1 or 2, wherein when parallel light having an emission peak wavelength of 300 nm or more and 1000 nm or less is incident, the total light transmittance of the diffused light emitted from the optical element is 93% or more. A light source and
the optical element according to claim 1 or 2, which is disposed on the output side of the light source;
the optical element diffuses the light from the light source;
A light source device that emits diffused light by the optical element. the optical element is disposed such that the surface on which the optical region is disposed faces the light source,
The light source device according to claim 9, which is used for sensing or lighting purposes.