Vehicle lighting fixtures

Abstract

This vehicular lamp (1) comprises: a light source unit (20); and a meta-lens (30) having a main surface (31s) as a meta-region through which light L emitted from the light source unit (20) passes, and in which are disposed a plurality of cells (33) including nanostructures (35) smaller than the longest wavelength of the light (L) emitted from the light source unit (20), wherein the main surface (31s), as the meta-region, changes the phase distribution of the light (L) passing through the main surface (31s).

Description

[Technical field]

[0001] The present invention relates to a vehicle lamp. [Background technology]

[0002] 2. Description of the Related Art Known vehicle lighting fixtures, typified by automobile headlights, include a projection lens through which light emitted from a light source passes. For example, Patent Document 1 listed below discloses such a vehicle lighting fixture.

[0003] In the vehicle lamp of Patent Document 1 below, the divergence angle of light emitted from a light source unit and incident on a projection lens is adjusted, and the light is irradiated forward of the vehicle.

[0004] Also, for example, Patent Document 2 below discloses a vehicle lamp that widens a light distribution pattern. In this vehicle lamp, an additional lens is disposed near the front of the peripheral portion of the projection lens. The additional lens deflects the light transmitted through the projection lens in a direction horizontally away from the optical axis. As a result, the light distribution pattern projected from the vehicle lamp to the outside becomes a light distribution pattern in which both the left and right ends of the light distribution pattern projected from the vehicle lamp to the outside when the additional lens is not disposed are widened to both the left and right sides, and is wider than the light distribution pattern when the additional lens is not disposed.

[0005] Also, a vehicle lamp is known in which the light source part is made of a light emitting module including a semiconductor light emitting element such as an LED (Light Emitting Diode). In addition, various configurations have been considered to make the light emitted from such a light emitting module a desired color. For example, the following Patent Document 3 discloses a light emitting module including an LED and a phosphor that is irradiated with a part of the light emitted from the LED and emits light of a different wavelength from the light. In this light emitting module, the light emitted from the phosphor and another part of the light emitted from the LED are multiplexed, and light of a different color from the color of the light emitted from the LED is emitted. In addition, the spectral distribution of the light emitted from this light emitting module includes two peaks, and the wavelength at one peak is approximately the same as the peak wavelength of the light emitted from the LED, and the wavelength at the other peak is approximately the same as the peak wavelength of the light emitted from the phosphor.

[0006] [Patent Document 1] JP 2012-169189 A [Patent Document 2] JP 2007-35467 A [Patent Document 3] Japanese Patent Application Publication No. 10-242513 Summary of the Invention

[0007] In a vehicle lamp such as that disclosed in the above-mentioned Patent Document 1, the size of the light distribution pattern of the emitted light can be easily set to a desired size. However, due to the diversification of vehicle designs, etc., there is a demand for miniaturization of vehicle lamps.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a vehicle lamp that can be made compact.

[0009] In order to achieve the above-mentioned objective, the vehicle lamp of the present invention comprises a light source unit and a metalens having a metaregion in which a plurality of cells including nanostructures smaller than the longest wavelength of light emitted from the light source unit are arranged and through which the light emitted from the light source unit passes, the metaregion being characterized in that it changes the phase distribution of the light passing through the metaregion.

[0010] In a projection lens in a vehicle lamp, at least one of the entrance surface and the exit surface is generally a curved surface, and the divergence angle of light emitted from the light source unit is adjusted by adjusting the shape of the curved surface. For this reason, such a projection lens requires a certain thickness to form the curved surface. On the other hand, the metalens in this vehicle lamp can adjust the divergence angle of the light by changing the phase distribution of the light from the light source unit by adjusting the arrangement of the multiple cells and the size of the nanostructure in each cell. For this reason, this metalens can adjust the divergence angle of the light from the light source unit even if the curvature of the meta region is made smaller than the curvature of the curved surface of the projection lens, and can be made thinner than the projection lens. For this reason, this vehicle lamp can be made smaller in size than the case where the divergence angle of the light from the light source unit is adjusted by the projection lens.

[0011] The metalens may have an incident surface on which the light from the light source unit is incident, the incident surface being convexly curved outward to refract the light so as to reduce the divergence angle of the light, and the light incident on the incident surface may be transmitted through the meta region.

[0012] Generally, when the divergence angle of light incident on the meta region becomes large, the design of the meta region tends to become complicated. In the metalens in this vehicle lamp, the light from the light source unit is incident on the meta region after the divergence angle is reduced by the curved incident surface. Therefore, for example, when the divergence angle of the light from the light source unit is reduced to a predetermined divergence angle by the metalens, the divergence angle of the light incident on the meta region can be reduced compared to when the incident surface on which the light from the light source unit is incident is flat. Therefore, according to this vehicle lamp, it is possible to suppress the design of the meta region from becoming complicated, and it is particularly useful when reducing the divergence angle of the light from the light source unit.

[0013] Alternatively, an incident surface of the metalens on which the light from the light source unit is incident may be provided with a plurality of grooves to diffract the light so as to reduce the divergence angle of the light, and the light that is incident on the incident surface may be transmitted through the meta region.

[0014] In the metalens of this vehicle lamp, the light from the light source unit is incident on the meta region after the divergence angle is reduced by the incident surface. Therefore, for example, when the metalens reduces the divergence angle of the light from the light source unit to a predetermined divergence angle, the divergence angle of the light incident on the meta region can be made smaller than when the incident surface on which the light from the light source unit is incident is flat. Therefore, this vehicle lamp can prevent the design of the meta region from becoming complicated, and is particularly useful when reducing the divergence angle of the light from the light source unit.

[0015] The above-mentioned vehicle lamp may further include a protective member having optical transparency and covering the meta region.

[0016] By using such a configuration, it is possible to prevent dust and other particles from getting between the nanostructures, from adhering to the nanostructures, and from scratching the nanostructures, and it is possible to appropriately adjust the divergence angle of the light from the light source unit.

[0017] In this case, the protective member may have a refractive index lower than the refractive index of the metalens and fill in the spaces between the nanostructures.

[0018] The metaregion may change the phase distribution of the reference light so that, when a reference light parallel to a reference axis perpendicular to the metaregion is incident on the metaregion at a specific position in the metaregion, the phase distribution of the reference light exiting the metalens becomes a specific phase distribution consisting of a remainder when a predetermined phase distribution is divided by 2π, the predetermined phase distribution being a phase distribution in which the amount of phase lag (rad) decreases and the rate of decrease of the amount of phase lag increases with increasing distance from the reference axis, the specific phase distribution may have a plurality of peaks, and the plurality of cells may be arranged such that, when viewed along the reference axis, two or more of the cells are located between adjacent peaks in a direction away from the specific position.

[0019] The meta-region is configured so that the phase distribution of the reference light is the above-mentioned predetermined phase distribution, thereby making it possible to reduce the divergence angle of the light that passes through the meta-region and is emitted from the metalens. Here, when the phase of the light is delayed by an integer multiple of 2π, the wavefront of the light can be considered to be the same as the wavefront of the light with no phase delay. Therefore, even if the meta-region is configured so that the phase distribution of the reference light is the above-mentioned specific phase distribution, the divergence angle can be reduced. Therefore, this vehicle lamp can reduce the divergence angle of the light from the light source unit by the metalens. Also, as described above, the specific phase distribution is made up of the remainder when a specific phase distribution in which the amount of phase delay and the rate of increase of the amount of phase delay increase as the distance from the specific position along the meta-region increases, is divided by 2π, and has multiple peaks. Therefore, the amount of phase delay in the specific phase distribution increases from zero as the distance from the specific position increases, approaches infinitely close to 2π, and becomes zero, and this change is repeated periodically. The fewer the number of cells arranged for one period of the above change, the greater the deviation between the phase distribution changed by the meta region and the specific phase distribution, and the lower the proportion of the energy of the light exiting the meta region at a divergence angle corresponding to the specific phase distribution relative to the energy of the light entering the meta region. In this vehicle lamp, two or more cells are arranged for one period of this change. By arranging the cells in this manner, it is possible to easily reduce the light energy loss caused by the metalens to a level suitable for use as a lens in a vehicle lamp.

[0020] When a plurality of cells are arranged as described above, the specific phase distribution may have three or more peaks, and the number of the cells located between the peaks may decrease with increasing distance from the specific position.

[0021] In addition, when a plurality of cells are arranged as described above, it is preferable that the shape of the nanostructure is cylindrical, and the number of the cells located between the peaks is 3 or more. The inventors have found that by adopting such a configuration, it is possible to make the ratio of the energy of the light exiting the metaregion at a divergence angle corresponding to a specific phase distribution with respect to the energy of the light incident on the metaregion 60% or more.

[0022] The meta region may have a minimum width of 10 mm or more.

[0023] In general, by making the lens larger, it becomes easier to increase the amount of light emitted from the lens. By adopting the above-mentioned configuration, it becomes easier to make the light distribution pattern of the light emitted from the metalens have the brightness required for the light distribution pattern of the light emitted from the vehicle headlamp. Note that, as the light distribution pattern of the light emitted from the vehicle headlamp, for example, a low beam or high beam light distribution pattern can be mentioned.

[0024] In addition, the meta region may change the phase distribution of the light passing through the meta region so that coma aberration occurs, and the divergence angle of the light passing through the meta region may be wider in the left-right direction of the light distribution pattern formed by the light than in a case where the coma aberration does not occur.

[0025] Coma aberration is an aberration in which a point image on the image plane does not form at a single point, but spreads out like a comet-like tail. In the image plane, light does not spread radially from the point image to the periphery of the point image due to coma aberration, but extends in a certain direction from the point image. This means that the divergence angle of light is widened by coma aberration. In a metalens, even if coma aberration does not occur, the divergence angle of light can be widened by adjusting the arrangement of multiple cells and the size and shape of the nanostructure in each cell. However, in the metaregion of the present invention, even if the divergence angle is the same as the divergence angle widened in the case where coma aberration does not occur, the divergence angle can be further widened in the left and right directions due to the above-mentioned extension of light due to coma aberration. Therefore, the light distribution pattern can be wider in the left and right directions than the light distribution pattern projected from a metalens that widens the divergence angle of light without generating coma aberration.

[0026] In addition, generally, the projection lens having a curved surface as described above is designed to suppress coma aberration. Therefore, when a projection lens is used, the spread of the divergence angle of light from the light source unit is suppressed, and the spread of the light distribution pattern projected outside the vehicle lamp is suppressed. In contrast, in the meta region of the metalens configured as a projection lens, the divergence angle is widened by coma aberration, so the light distribution pattern may be wider than the light distribution pattern projected from the projection lens.

[0027] Furthermore, when the metaregion changes the phase distribution of light passing through the metaregion so as to generate coma aberration, the metaregion may make the amount of spread of the divergence angle to the left due to the coma aberration equal to the amount of spread of the divergence angle to the right due to the coma aberration. By adopting such a configuration, the amount of spread at the right end and the left end of the light distribution pattern can be the same, which can make the design of the metalens easier than when the amounts of spread are not the same.

[0028] Alternatively, the meta region may be configured to make one of the amount of spread of the divergence angle to the left due to the coma aberration and the amount of spread of the divergence angle to the right due to the coma aberration larger than the other. With this configuration, one of the amount of spread of the right end of the light distribution pattern and the amount of spread of the left end of the light distribution pattern becomes larger than the other, making it easier for the driver of the vehicle to view an object located on the side where the light distribution pattern is spread.

[0029] In addition, when the meta region changes the phase distribution of the light passing through the meta region so as to generate coma aberration, the meta region may widen the divergence angle of the light passing through the meta region in the vertical direction of the light distribution pattern formed by the light, compared to when the coma aberration does not occur. By adopting such a configuration, it may become easier for the driver of the vehicle to see objects such as guide signs and road surfaces.

[0030] Furthermore, when the metaregion changes the phase distribution of light passing through the metaregion so as to generate coma aberration, the metaregion may make the amount of spread of the divergence angle in the left-right direction caused by the coma aberration greater than the amount of spread of the divergence angle in the up-down direction caused by the coma aberration. With this configuration, the light distribution pattern spreads more in the left-right direction than in the up-down direction without changing the amount of light passing through the metalens, and the light distribution pattern can ensure that the driver's field of vision is wider in the left-right direction than in the up-down direction.

[0031] In addition, the meta region may be configured so that the bending force of the meta region bending infrared light contained in the light passing through the meta region is smaller than the bending force of the meta region bending visible light contained in the light passing through the meta region.

[0032] As described above, the metaregion changes the phase distribution of the light passing through the metaregion. This phase distribution changes depending on the arrangement of the multiple cells and the size and shape of the nanostructure in each cell. Therefore, the metaregion adjusts these to change the phase distribution of the light passing through the metaregion, and makes the bending force of the metaregion that bends the infrared light contained in the light passing through the metaregion smaller than the bending force of the metaregion that bends the visible light contained in the light. The bending force indicates the force with which the metaregion bends the light passing through the metaregion. The smaller the bending force, the smaller the bending angle of the light passing through the metaregion, and the suppression of the focusing of the light. Therefore, for example, even if sunlight enters the inside of the vehicle lamp from the outside of the vehicle lamp, in this vehicle lamp, the bending angle of the infrared light contained in the sunlight is smaller than the bending angle of the visible light contained in the sunlight due to the bending force. Therefore, according to this vehicle lamp, compared to the projection lens, the metaregion can suppress the focusing of the infrared light traveling from the metalens to the light source unit. When the concentration of infrared light is suppressed, deterioration of the light source unit due to the concentration of infrared light can be suppressed compared to a projection lens.

[0033] In addition, when the bending force of a metaregion that bends infrared light is smaller than the bending force of a metaregion that bends visible light, the metaregion may be configured such that, when the visible light and the infrared light have a wavelength ratio of 1:1.5, the amount of phase modulation of the infrared light is less than 0.6 times the amount of phase modulation of the visible light.

[0034] For example, in a refractive lens made of acrylic, if the bending force of the refractive lens that bends visible light is set to 1, the bending force of the refractive lens that bends infrared light is approximately 0.98. Also, in a refractive lens made of polycarbonate, if the bending force of the refractive lens that bends visible light is set to 1, the bending force of the refractive lens that bends infrared light is approximately 0.98. Therefore, whether the lens is made of acrylic or polycarbonate, the bending force of the refractive lens that bends infrared light is approximately 0.98 times the bending force of the refractive lens that bends visible light. In this case, the refractive lens makes it easier to focus infrared light. The bending force of the meta-region is approximately proportional to the product of the phase modulation amount of light passing through the meta-region and the wavelength of the light. In this vehicle lamp, in a visible light and infrared light having a wavelength ratio of 1:1.5, the amount of phase modulation of infrared light is less than 0.6 times that of visible light, so that the bending force of the meta region that bends infrared light is less than 0.9 times that of the meta region that bends visible light. When the bending force of the meta region that bends infrared light and the bending force of the refractive lens that bends infrared light are compared based on the respective bending forces that bend visible light, the bending force of the meta region that bends infrared light is smaller than the bending force of the refractive lens that bends infrared light. Therefore, this vehicle lamp can suppress the concentration of infrared light more than a refractive lens.

[0035] Furthermore, when the bending force of the metaregion that bends infrared light is smaller than the bending force of the metaregion that bends visible light, the longest wavelength of the visible light may be 660 nm and the shortest wavelength of the infrared light may be 1000 nm.

[0036] In addition, when the bending force of the meta-region that bends infrared light is smaller than the bending force of the meta-region that bends visible light, the shape of the nanostructure may be a cylinder. With this configuration, even if the visible light from the light source is randomly polarized, the visible light can be efficiently bent.

[0037] At least one resonant wavelength in the metalens may be greater than or equal to 800 nm and less than 2400 nm.

[0038] In a metalens, a phenomenon may occur in which the transmittance of light of a specific wavelength becomes extremely lower than the transmittance of light of other wavelengths, and it is known that there are generally a plurality of such specific wavelengths. These specific wavelengths are wavelengths at which the non-transmittance of light in the metalens is at a peak, and are called resonant wavelengths. These resonant wavelengths are determined according to the size and shape of the nanostructure in each cell, the refractive index of the material constituting the nanostructure, and the like. In this vehicle lamp, as described above, at least one resonant wavelength in the metalens is 800 nm or more and less than 2400 nm. Generally, sunlight near the earth's surface contains light in the wavelength band from 800 nm to 2400 nm. Therefore, according to this vehicle lamp, when sunlight passes through the metalens and is irradiated to the light source unit, the amount of sunlight irradiated to the light source unit with a wavelength of 800 nm to 2400 nm can be reduced compared to when the metalens is used as a projection lens. Therefore, according to this vehicle lamp, the amount of heating of the light source unit by sunlight can be reduced compared to when the metalens is used as a projection lens, and deterioration of the light source unit by sunlight can be suppressed.

[0039] Additionally, if at least one resonant wavelength in the metalens is greater than or equal to 800 nm and less than 2400 nm, the at least one resonant wavelength may be in the range of greater than or equal to 800 nm and less than 900 nm.

[0040] Generally, the intensity of sunlight near the earth's surface tends to decrease as the wavelength becomes longer in the wavelength band of 800 nm or more. The spectral distribution of sunlight has multiple valleys where the intensity suddenly decreases. The minimum intensity in this valley is, for example, 50% or less of the intensity in the vicinity of the valley. Such valleys tend not to be located in the range of 800 nm or more and less than 900 nm. For this reason, the above-mentioned configuration makes it easier to reduce the amount of heating of the light source unit by sunlight when the sunlight passes through the metalens and is irradiated onto the light source unit.

[0041] Furthermore, if at least one resonant wavelength in the metalens is greater than or equal to 800 nm and less than 2400 nm, the spectral distribution of the light emitted from the light source unit may have a plurality of peaks, and the plurality of resonant wavelengths may be different from the respective wavelengths of the plurality of peaks.

[0042] Light with a wavelength at the peak of the above-mentioned spectral distribution tends to have a large effect on the color tone of the light emitted from the vehicle lamp. Therefore, according to this vehicle lamp, it is possible to suppress a decrease in the transmittance of light with a wavelength that has a large effect on the color tone of the emitted light through the metalens, and it is possible to emit light with a desired color tone.

[0043] In this case, all of the plurality of resonant wavelengths may not be included in the wavelength band of the light emitted from the light source unit.

[0044] This vehicle lamp can emit light of a desired color tone, compared to a case in which at least one resonant wavelength is included in the wavelength band of light emitted from the light source unit.

[0045] Additionally, if at least one resonant wavelength of the metalens is greater than or equal to 800 nm and less than 2400 nm, the metalens may reduce the divergence angle of the light from the light source that transmits through the metalens.

[0046] Furthermore, a spectral distribution of the light emitted from the light source unit may have a plurality of peaks, and a plurality of resonant wavelengths in the metalens may be different from the respective wavelengths of the plurality of peaks.

[0047] In this vehicle lamp, as described above, the spectral distribution of the light emitted from the light source unit has multiple peaks, and therefore the color tone of the emitted light can be made to be a desired color tone, compared to a case in which this spectral distribution has only one peak. Furthermore, in this vehicle lamp, as described above, the multiple resonant wavelengths in the metalens are different from the wavelengths of the multiple peaks. The light of each wavelength in the multiple peaks significantly affects the color tone of the light emitted from the vehicle lamp. For this reason, according to this vehicle lamp, it is possible to suppress a decrease in the transmittance through the metalens of light of a wavelength that significantly affects the color tone of the emitted light, and it is possible to emit light of a desired color tone.

[0048] In addition, when the spectral distribution of the light emitted from the light source unit has multiple peaks, at least one of the multiple resonant wavelengths may be longer than the shortest wavelength and shorter than the longest wavelength among the respective wavelengths of the multiple peaks.

[0049] When the multiple resonant wavelengths are to be designed so as not to include any resonant wavelength that is longer than the shortest wavelength and shorter than the longest wavelength, the design of the size and shape of the nanostructure in each cell, the arrangement of the cells, etc. tends to become complicated. For this reason, by using the above-mentioned configuration, it is possible to suppress these designs from becoming complicated.

[0050] In this case, the wavelength of the light having the smallest intensity between the adjacent peaks may be the same as the at least one of the plurality of resonant wavelengths.

[0051] With this configuration, the decrease in the amount of emitted light can be suppressed compared to when the wavelength of light excluding the light having the smallest intensity between the peaks is the same as the resonance wavelength.

[0052] In addition, when the spectral distribution of the light emitted from the light source unit has multiple peaks, the multiple resonant wavelengths may include a specific resonant wavelength included in the wavelength band of the light from the light source unit, and a ratio of the intensity of the light of the specific resonant wavelength in the light to the maximum intensity in the entire spectral distribution of the light may be 0.1 or less.

[0053] With this configuration, the reduction in the amount of emitted light can be suppressed compared to when the ratio exceeds 0.1.

[0054] As described above, according to the present invention, a vehicle lamp that can be made compact can be provided. [Brief description of the drawings]

[0055] [Figure 1] 1 is a cross-sectional view that shows a schematic view of a vehicle lamp according to a first embodiment of the present invention. [Diagram 2] 2 is a front view showing a schematic view of the light source unit shown in FIG. [Diagram 3] FIG. 2 is an enlarged front view showing a portion of one main surface of the metalens shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating a schematic view of a part of a predetermined phase distribution in the first embodiment. [Diagram 5] FIG. 4 is a diagram illustrating a schematic view of a part of a specific phase distribution in the first embodiment. [Figure 6] FIG. 11 is a cross-sectional view illustrating a schematic configuration of a metalens in a second embodiment. [Figure 7] FIG. 11 is a cross-sectional view illustrating a schematic view of a metalens in a third embodiment. [Figure 8] FIG. 11 is a view similar to FIG. 1 showing a vehicle lamp according to a fourth embodiment. [Figure 9] FIG. 1 is a cross-sectional view that illustrates a schematic diagram of a protective member and a metalens according to a first modified example. [Figure 10] FIG. 13 is a diagram showing a light distribution pattern for low beam formed on a virtual vertical screen located at a position 25 m ahead of a vehicle lamp in a fifth embodiment. [Figure 11]FIG. 13 is a diagram showing an example of a light distribution pattern in a second modified example. [Figure 12] FIG. 13 is a diagram showing another example of a light distribution pattern in the second modified example. [Figure 13] FIG. 13 is a diagram showing an example of a light distribution pattern in a third modified example. [Figure 14] FIG. 13 is a diagram showing an example of a light distribution pattern in a fourth modified example. [Figure 15] FIG. 13 is a diagram showing the relationship between the diameter of the nanostructure in the sixth embodiment and the amount of phase modulation of visible light with a longest wavelength of 660 nm and infrared light with a shortest wavelength of 1000 nm. [Figure 16] FIG. 11 is a view similar to that of FIG. 1 showing a vehicle lamp according to a seventh embodiment. [Figure 17] FIG. 23 is a diagram illustrating a schematic diagram of the spectral distribution of light emitted from a light source unit and the light transmittance distribution of a metalens in the seventh embodiment. [Figure 18] FIG. 13 is a diagram illustrating generally the spectral distribution of sunlight near the earth's surface and the light transmittance distribution of a metalens according to a seventh embodiment. [Figure 19] 17A and 17B are diagrams illustrating the spectral distribution of light emitted from a light source unit and the light transmittance distribution of a metalens according to a fifth modified example. [Figure 20] FIG. 23 is a diagram illustrating a schematic diagram of the spectral distribution of light emitted from a light source unit and the light transmittance distribution of a metalens in the eighth embodiment. [Figure 21] FIG. 21 is a diagram similar to FIG. 20 showing the spectral distribution of light emitted from a light source unit and the light transmittance distribution of a metalens according to a sixth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] A preferred embodiment of the vehicle lamp according to the present invention will be described in detail below with reference to the drawings. The embodiments exemplified below are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified and improved without departing from the spirit of the present invention. In addition, the components in the embodiments exemplified below may be appropriately combined in the present invention. In addition, in the drawings referred to below, the dimensions of each component may be changed in order to facilitate understanding.

[0057] (First embodiment) FIG. 1 is a diagram showing a vehicle lamp in a first embodiment of the present invention, and is a diagram showing a schematic vertical cross section of the vehicle lamp. The vehicle lamp 1 of this embodiment is a headlamp for an automobile. Automotive headlamps are generally provided on the left and right sides of the front of the vehicle. In this specification, "right" means the right side in the traveling direction of the vehicle, and "left" means the left side in the traveling direction of the vehicle. The left and right headlamps have the same configuration, except that their shapes are approximately symmetrical in the left-right direction. For this reason, in this embodiment, one of the headlamps will be described. As shown in FIG. 1, the vehicle lamp 1 of this embodiment mainly includes a housing 10, a light source unit 20, and a metalens 30.

[0058] The housing 10 of this embodiment mainly comprises a lamp housing 11, a front cover 12, and a back cover 13. The front of the lamp housing 11 is open, and the front cover 12 is fixed to the lamp housing 11 so as to close the opening. In addition, an opening smaller than the front is formed in the rear of the lamp housing 11, and the back cover 13 is fixed to the lamp housing 11 so as to close the opening.

[0059] The space formed by the lamp housing 11, the front cover 12 that closes the front opening of the lamp housing 11, and the back cover 13 that closes the rear opening of the lamp housing 11 is a lamp chamber R, and the light source unit 20 and the metalens 30 are housed in this lamp chamber R. The back cover 13 is openable and detachable with respect to the lamp housing 11 in order to replace the light source unit 20 and the metalens 30 through the rear opening of the lamp housing 11. The front cover 12 is made of a light-transmitting material, and light emitted from the light source unit 20 and passing through the metalens 30 passes through the front cover 12. The lamp housing 11 and the back cover 13 are made of, for example, resin.

[0060] FIG. 2 is a front view showing the light source unit 20 shown in FIG. 1. In this embodiment, as shown in FIG. 1 and FIG. 2, the light source unit 20 has a plurality of light-emitting elements 21 that emit light, and a circuit board 22 on which the plurality of light-emitting elements 21 are mounted. In FIG. 1 and FIG. 2, for ease of viewing, only one light-emitting element 21 is indicated by a reference numeral, and the reference numerals of the other light-emitting elements 21 are omitted. The plurality of light-emitting elements 21 are arranged in a matrix to form rows in the vertical and horizontal directions, and emit light forward. Each of the plurality of light-emitting elements 21 is capable of individually changing the amount of light emitted by the power supplied to each of the light-emitting elements 21. In addition, these light-emitting elements 21 are phosphor-type LEDs (Light Emitting Diodes) that emit white light, the light source unit 20 is a so-called LED array, and the light emitted from the light source unit 20 has a predetermined wavelength band. In addition, the number and configuration of the light-emitting elements 21 are not particularly limited. For example, the light emitting element 21 may be configured to include a plurality of LEDs that emit light of different wavelengths, or may be configured to include a plurality of LDs (Laser Diodes) that emit light of different wavelengths.

[0061] Such a light source unit 20 can emit light having a predetermined light distribution pattern by selecting the light emitting element 21 that emits light, and can change the outer shape of the predetermined light distribution pattern by changing the selection. Also, the light source unit 20 can adjust the intensity distribution of light in the predetermined light distribution pattern by adjusting the amount of light emitted from each light emitting element 21. In other words, the light source unit 20 can emit light having a predetermined light distribution pattern according to the amount of light emitted from the multiple light emitting elements 21, and can change the light distribution pattern of the emitted light. Note that the light source unit 20 does not necessarily have to be able to change the light distribution pattern of the emitted light.

[0062] The wavelength of the light L emitted from the light source unit 20 in this embodiment is included in the wavelength band of visible light. The wavelength band of visible light is approximately 380 nm to 780 nm. Since the light L emitted from the light source unit 20 is light emitted from a plurality of light-emitting elements 21, the wavelength of the light emitted from each light-emitting element 21 is approximately the same as the wavelength of the light L emitted from the light source unit 20. The wavelength of the light L does not have to be included in the wavelength band of visible light.

[0063] The metalens 30 of this embodiment is a flat member and is configured to adjust the divergence angle of light transmitted in the thickness direction. The metalens 30 is disposed in front of the light source unit 20, and light L emitted from the light source unit 20 is incident on one planar principal surface 31s and exits from the other planar principal surface 32s. For this reason, the principal surface 31s is an entrance surface on which the light L from the light source unit 20 is incident, and the principal surface 32s is an exit surface from which the light L from the light source unit 20 that is incident on the principal surface 31s exits.

[0064] FIG. 3 is a front view showing an enlarged portion of one of the principal surfaces 31s of the metalens 30 shown in FIG. 1. As shown in FIG. 3, the principal surface 31s has a plurality of cells 33 formed by being divided in two different directions, and each cell 33 is provided with a nanostructure 35. In FIG. 3, the boundary between adjacent cells 33 is shown by a dashed line. For ease of viewing, only one cell 33 and one nanostructure 35 are labeled, and the other cells 33 and nanostructures 35 are omitted. In this embodiment, the plurality of cells 33 are arranged over the entire principal surface 31s, and it can be understood that the entire principal surface 31s is a metaregion in which the plurality of cells 33 including the nanostructures 35 are arranged. In addition, the metalens 30 has a disk shape, and the plurality of cells 33 are arranged in the radial direction and the circumferential direction based on the center of gravity 31g of the principal surface 31s. In addition, at the center of gravity 31g as a specific position, a reference axis 36 perpendicular to the principal surface 31s intersects with the light source unit 20. Furthermore, the light emitting elements 21 of the light source unit 20 are arranged along a plane that is approximately perpendicular to the reference axis 36. Furthermore, the diameter of the metalens 30 is 10 mm or more, for example 50 mm. Therefore, the minimum width of the metaregion is 10 mm or more. The area of ​​the principal surface 31s excluding the nanostructures 35 is a flat surface, and the nanostructures 35 are protrusions that extend from the principal surface 31s toward the light source unit 20. Such nanostructures 35 are configured as part of the metalens 30 by ultrafine processing of the principal surface 31s, and are integrated with the metalens 30.

[0065] The arrangement of the multiple cells 33 and the position and range of the metaregion are not particularly limited. For example, the metaregion may be a part of the main surface 31s, or at least a part of the main surface 32s on the opposite side to the light source unit 20. The metaregion may be at least a part of the main surface 31s and at least a part of the main surface 32s. The shape of the cells 33 shown in FIG. 3 is generally rectangular, but is not particularly limited. The size and shape of the multiple cells 33 may be different from each other. The sizes of the metalens 30 and the metaregion are not particularly limited, and for example, the diameter of the metalens 30 may be smaller than 10 mm. The outer shape of the metalens 30 is not particularly limited, and may be, for example, rectangular.

[0066] In this embodiment, the nanostructure 35 has a cylindrical shape and a diameter smaller than the longest wavelength of the light emitted from the light source unit 20. The shape of the nanostructure 35 is not particularly limited as long as the width of the nanostructure 35 is smaller than the longest wavelength of the light emitted from the light source unit 20. For example, the shape of the nanostructure 35 may be a square prism shape or a C-shape. The nanostructure 35 may be composed of a pair of square prisms arranged at a predetermined interval. The shape of the nanostructure 35 in each cell 33 may be different. A plurality of nanostructures 35 may be provided in each cell 33, and the number of nanostructures 35 in each cell 33 may be different. Examples of materials constituting the metalens 30 include glass, resin, and the like. The materials constituting the nanostructure 35 and the parts other than the nanostructure 35 may be the same or different.

[0067] A cell 33 including such a nanostructure 35 can modulate the phase of light L passing through the cell 33. By adjusting the arrangement of the multiple cells 33 and the size, shape, and the like of the nanostructure 35 in each cell 33, the phase distribution of light L passing through the metaregion can be changed, and the divergence angle of white light L passing through the metalens 30 can be changed. In this embodiment, the arrangement of the multiple cells 33 and the size, shape, and the like of the nanostructure 35 in each cell 33 are adjusted so that the divergence angle of the light L is reduced to a predetermined divergence angle. For this reason, it can be understood that the metaregion is configured to modulate the phase of light L so that the divergence angle of the light L becomes a predetermined divergence angle.

[0068] Specifically, the metaregion of this embodiment is configured such that, when a reference light parallel to the reference axis 36 is incident on the metaregion, the phase distribution of the reference light output from the metalens 30 becomes a specific phase distribution consisting of a remainder when the predetermined phase distribution 50 shown in FIG. 4 is divided by 2π. FIG. 4 is a diagram that shows a schematic view of a portion of the predetermined phase distribution 50 in this embodiment, and shows the predetermined phase distribution 50 in a vertical plane including the reference axis 36. The phase distribution of the reference light output from the metalens 30 is a phase distribution in a virtual plane perpendicular to the reference axis 36, and in this embodiment, the virtual plane is a phase distribution in a plane along the principal surface 32s, which is the output surface of the metalens 30. In FIG. 4, the x-axis is the amount of phase delay (rad), the y-axis is the distance from the intersection 32p of the reference axis 36 and the principal surface 32s in the direction perpendicular to the reference axis 36, and r is the radius of the metalens 30. As shown in FIG. 4, the predetermined phase distribution 50 in a vertical plane including the reference axis 36 is a curve in which the amount of phase delay decreases and the rate of decrease of the amount of phase delay increases as the distance from the reference axis 36 increases in a direction perpendicular to the reference axis 36. Although not illustrated, the predetermined phase distribution 50 in any plane including the reference axis 36 is a curve similar to the predetermined phase distribution 50 shown in FIG. 4. Therefore, the predetermined phase distribution 50 can be understood as a phase distribution in which the amount of phase delay decreases and the rate of decrease of the amount of phase delay increases as the distance from the reference axis 36 increases. Here, by configuring the metaregion so that the phase distribution of the reference light is the predetermined phase distribution 50, the divergence angle of the light that passes through the metaregion and is emitted from the metalens 30 can be reduced. Furthermore, when the phase of light is delayed by an integer multiple of 2π, the wavefront of the light can be considered to be the same as the wavefront of light with no phase delay. Therefore, it is possible to reduce the divergence angle of light L even in the metalens 30 of the present embodiment in which the meta region is configured so that the phase distribution of the above-mentioned reference light is a specific phase distribution consisting of the remainder when the predetermined phase distribution 50 is divided by 2π. Note that the predetermined phase distribution 50 may be any phase distribution in which the amount of phase lag decreases and the rate of decrease of the amount of phase lag increases with increasing distance from the reference axis 36, and the amount of phase lag and the rate of decrease of the amount of phase lag are adjusted according to the degree of adjustment of the divergence angle, etc.Furthermore, the reference axis 36 is not limited to one that passes through the center of gravity 31g, but may be any axis that is perpendicular to the meta region at a specific position in the meta region.

[0069] In this embodiment, as shown in FIG. 5, a specific phase distribution 60 consisting of a remainder obtained by dividing a predetermined phase distribution 50 by 2π has a plurality of peaks 61. FIG. 5 is a diagram that shows a schematic view of a part of the specific phase distribution 60 in this embodiment, and shows a part of the specific phase distribution 60 in a vertical plane including the reference axis 36. In FIG. 5, the x-axis is the phase delay amount (rad), the y-axis is the distance from the intersection 32p of the reference axis 36 and the main surface 32s in the direction perpendicular to the reference axis 36, and r is the radius of the metalens 30. In FIG. 5, a dotted line indicating y=r and a dotted line indicating x=2π are also shown. In FIG. 5, for ease of viewing, only four peaks 61 are labeled, and the labels of the other peaks 61 are omitted. As shown in FIG. 5, the phase delay amount in the specific phase distribution 60 on the vertical plane including the reference axis 36 periodically repeats a change from a value infinitesimally close to 2π to zero as it moves away from the reference axis 36 in the direction perpendicular to the reference axis 36. The width of this period narrows as it moves away from the reference axis 36, with the maximum width being approximately 400 μm, and the width of the period adjacent to the period with the maximum width being approximately 100 μm. The minimum width is approximately 1 μm. As described above, the specified phase distribution 50 on any plane including the reference axis 36 is a curve similar to the specified phase distribution 50 shown in FIG. 4. Therefore, the phase delay amount in the specific phase distribution 60 on any plane including the reference axis 36 periodically repeats a change from a value infinitesimally close to 2π to zero as it moves away from the reference axis 36. Therefore, it can be understood that the phase delay amount in the specific phase distribution 60 periodically repeats the above change as it moves away from the reference axis 36. Here, the fewer the number of cells arranged for one period of the above change, the greater the deviation between the phase distribution modulated by the meta region and the specific phase distribution 60, and the lower the ratio of the energy of the light exiting the meta region at a divergence angle according to the specific phase distribution 60 to the energy of the light entering the meta region. In this embodiment, the multiple cells 33 are arranged such that, when viewed along the reference axis 36, two or more cells 33 are located between adjacent peaks 61 in the direction away from the center of gravity 31g. In other words, two or more cells 33 are arranged for one period of the above change.By arranging the cells 33 in this manner, it is possible to easily reduce the loss of light energy caused by the metalens 30 to a level suitable for use as a lens in a vehicle lamp. In addition, in this embodiment, the shape of the nanostructure 35 is cylindrical. The inventors have found that by arranging three or more cells 33 for one period of the above-mentioned change and by making the shape of the nanostructure 35 cylindrical, the ratio of the energy of light emitted from the metaregion at a divergence angle corresponding to the specific phase distribution 60 to the energy of light incident on the metaregion can be made 60% or more. For this reason, from the viewpoint of reducing the loss of light energy in the metalens 30, such a configuration is preferable. In addition, in this embodiment, the specific phase distribution 60 has three or more peaks 61. In addition, the number of cells 33 located between adjacent peaks 61 in a direction away from the center of gravity 31g when viewed along the reference axis 36 decreases with increasing distance from the center of gravity 31g.

[0070] In the vehicle lamp 1 of this embodiment, the light L adjusted by the metalens 30 to have a small divergence angle is emitted toward the front of the vehicle through the front cover 12. Therefore, the vehicle lamp 1 of this embodiment can easily adjust the size of the light distribution pattern of the emitted light to a desired size. Also, as described above, the light source unit 20 can change the light distribution pattern of the emitted light. Therefore, the vehicle lamp 1 can, for example, switch between emitting a high beam and a low beam, or emit an ADB (Adaptive Driving Beam).

[0071] As described above, the vehicle lamp 1 of this embodiment includes the light source unit 20 and the metalens 30. The metalens 30 has a main surface 31s as a metaregion. A plurality of cells 33 including nanostructures 35 smaller than the longest wavelength of the light L emitted from the light source unit 20 are arranged on the main surface 31s, and the light L emitted from the light source unit 20 passes through the main surface 31s. The main surface 31s as a metaregion changes the phase distribution of the light L passing through the main surface 31s. Here, in a projection lens in a vehicle lamp, at least one of the entrance surface and the exit surface is generally a curved surface, and the divergence angle of the light emitted from the light source unit is adjusted by adjusting the shape of the curved surface. For this reason, such a projection lens requires a certain thickness to form the curved surface. On the other hand, the metalens 30 in the vehicle lamp 1 of this embodiment can adjust the divergence angle of the light L by changing the phase distribution of the light L from the light source unit by adjusting the arrangement of the multiple cells 33 and the size of the nanostructures 35 in each cell 33, etc. For this reason, the metalens 30 of this embodiment can adjust the divergence angle of the light from the light source unit 20 even if the curvature of the main surface 31s as a meta region is made smaller than the curvature of the curved surface of the above-mentioned projection lens, for example, and can be made thinner than the above-mentioned projection lens. For this reason, the vehicle lamp 1 of this embodiment can be made more compact than the case in which the divergence angle of the light L from the light source unit 20 is adjusted by the above-mentioned projection lens.

[0072] Generally, by making a lens larger, it becomes easier to increase the amount of light emitted from the lens. In this embodiment, the minimum width of the main surface 31s as the meta region is 10 mm or more. Therefore, in this embodiment, the light distribution pattern of the light emitted from the metalens 30 can be easily adjusted to the brightness required for the light distribution pattern of the light emitted from the vehicle headlamp. Note that examples of the light distribution pattern of the light emitted from the vehicle headlamp include a low beam and a high beam light distribution pattern.

[0073] Second embodiment Next, a second embodiment of the present invention will be described in detail. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified. In this embodiment, the configuration of the metalens 30 is different from that of the first embodiment.

[0074] FIG. 6 is a cross-sectional view that shows a schematic cross section of the metalens in the thickness direction of the metalens. As shown in FIG. 6, in the metalens 30 of the present embodiment, the entirety of the main surface 31s as an incident surface on which the light L from the light source unit 20 is incident is a curved surface that is curved in a convex shape toward the outside. In the main surface 31s that is curved in this manner, the light L from the light source unit 20 is refracted so that the divergence angle of the light L from the light source unit 20 becomes small. In addition, the entirety of the main surface 32s as an exit surface from which the light L from the light source unit 20 is exited is a metaregion in which a plurality of cells 33 including nanostructures 35 are arranged, and the light L from the light source unit 20 that is incident on the main surface 31s is transmitted through the metaregion. In addition, the reference axis 36 is perpendicular to the main surface 32s at the center of gravity 32g as a specific position on the main surface 32s, and intersects with the light source unit 20. Then, similarly to the first embodiment, the metaregion is configured so that, when reference light parallel to the reference axis 36 is incident on the metaregion, the phase distribution of the reference light exiting the metalens 30 becomes a specific phase distribution 60 consisting of a remainder when a predetermined phase distribution 50 is divided by 2π. Note that the principal surface 31s serving as the incident surface only needs to be curved outwardly in a convex manner to refract the light L from the light source unit 20 so as to reduce the divergence angle of the light L, and may be configured so that a portion of the principal surface 31s is curved outwardly in a convex manner.

[0075] Generally, when the divergence angle of light incident on the metaregion increases, the design of the metaregion tends to become complicated. In the metalens 30 of this embodiment, the light L from the light source unit 20 is incident on the main surface 32s as the metaregion after the divergence angle is reduced by the main surface 31s, which is a curved entrance surface. Therefore, in this embodiment, the divergence angle of the light L from the light source unit 20 incident on the metaregion can be made smaller than when the main surface 31s is a flat surface. Therefore, the vehicular lamp 1 of this embodiment can prevent the design of the metaregion from becoming complicated, which is particularly useful when the divergence angle of the light L from the light source unit 20 is reduced as in this embodiment.

[0076] At least a part of the main surface 31s may be a meta region, the main surface 32s may be curved convexly outward, and the light L transmitted through the meta region may be emitted from the main surface 32s. In general, when the angle at which the meta region adjusts the divergence angle of the light increases, the design of the meta region tends to become complicated. With this configuration, the angle at which the meta region reduces the divergence angle of the light L can be made smaller than when the main surface 32s is a flat surface, and the design of the meta region can be prevented from becoming complicated.

[0077] Third embodiment Next, a third embodiment of the present invention will be described in detail. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified. In this embodiment, the configuration of the metalens 30 is different from that of the first embodiment.

[0078] FIG. 7 is a cross-sectional view that shows a schematic diagram of the metalens 30 of this embodiment, and is a cross-section of the metalens 30 in the thickness direction. As shown in FIG. 7, in the metalens 30 of this embodiment, a plurality of grooves 37 are provided in the planar main surface 31s serving as an incident surface on which the light L from the light source unit 20 is incident. In FIG. 7, for ease of viewing, the grooves 37 are exaggerated, and only one groove 37 is marked with a reference number, while the reference numbers of the other grooves 37 are omitted. Each groove 37 extends along a circle centered on the center of gravity 31g that is the center of the main surface 31s. In this manner, the main surface 31s provided with a plurality of grooves 37 diffracts the light L from the light source unit 20 so that the divergence angle of the light L is reduced. In other words, the shape, depth, width, position, and the like of the grooves 37 are adjusted so that the light L is diffracted in this manner, and it can be understood that the main surface 31s diffracts the light L in this manner. Moreover, the entirety of the main surface 32s from which the light L from the light source unit 20 is emitted is a metaregion in which a plurality of cells 33 including nanostructures 35 are arranged, and the light L from the light source unit 20 passes through the metaregion. The reference axis 36 is perpendicular to the main surface 32s at the center of gravity 32g as a specific position on the main surface 32s, and intersects with the light source unit 20. Similarly to the first embodiment, the metaregion is configured such that when a reference light parallel to the reference axis 36 is incident on the metaregion, the phase distribution of the reference light emitted from the metalens becomes a specific phase distribution 60 consisting of a remainder obtained by dividing a predetermined phase distribution 50 by 2π. Note that the main surface 31s as the incident surface is provided with a plurality of grooves 37, and it is sufficient that the grooves 37 diffract the light L from the light source unit 20 so that the divergence angle of the light L is small, and the shape, number, position, etc. of the grooves 37 are not limited. The grooves 37 may be provided on a curved main surface 31s.

[0079] Furthermore, in the metalens 30 of this embodiment, the light L from the light source unit 20 is incident on the metaregion after the divergence angle is reduced by the principal surface 31s, which is the incident surface. For this reason, the metaregion can reduce the angle of divergence of the light L incident on the principal surface 31s, compared to when the principal surface 31s on which the light L from the light source unit 20 is incident is flat. Therefore, the vehicular lamp 1 of this embodiment can prevent the design of the metaregion from becoming complicated, which is particularly useful when reducing the divergence angle of the light L from the light source unit 20 as in this embodiment.

[0080] In order to prevent the design of the meta region from becoming complicated, the principal surface 31s may be curved convexly outward, and may be provided with a plurality of grooves 37, so that the principal surface 31s diffracts the light L from the light source unit 20. In addition, at least a part of the principal surface 31s may be a meta region, and the principal surface 32s may diffract the light L that has passed through the meta region so that the divergence angle is reduced. With this configuration, the angle at which the divergence angle of the light L is reduced by the meta region can be reduced compared to when the principal surface 32s is a flat surface, and the design of the meta region can be prevented from becoming complicated.

[0081] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described in detail. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified.

[0082] Fig. 8 is a diagram showing the vehicle lamp 1 of this embodiment in the same manner as Fig. 1. Note that the housing 10 and the light source unit 20 are omitted in Fig. 8. As shown in Fig. 8, the vehicle lamp 1 of this embodiment differs from the vehicle lamp 1 of the first embodiment in that it further includes a protective member 40 having optical transparency.

[0083] The protective member 40 of this embodiment is composed of a main body portion 41 and a rib 42. The main body portion 41 is a disk-shaped member, and is disposed such that one principal surface 43s faces the principal surface 31s of the metalens 30 at a predetermined distance. In a direction parallel to the reference axis 36, the entire principal surface 31s as a metaregion overlaps with the main body portion 41. The rib 42 is provided on the principal surface 43s of the main body portion 41, and protrudes toward the metalens 30. The rib 42 extends along the entire circumference along the outer edge of the main body portion 41. The inner peripheral surface of the rib 42 is bonded to the outer peripheral surface of the metalens 30 along the entire circumference, and the protective member 40 is fixed to the metalens 30. Such a protective member 40 covers the principal surface 31s as a metaregion without contacting the principal surface 31s, and the principal surface 31s is exposed to a closed space 45 formed by the protective member 40 and the metalens 30. The main body 41 and the ribs 42 are integrally formed, and examples of materials constituting the protective member 40 include glass and resin.

[0084] In this embodiment, light L emitted from the light source unit 20 passes through the main body 41 of the protective member 40 and enters the metalens 30, where the divergence angle of the light L is adjusted, and the light L with the adjusted divergence angle is emitted toward the front of the vehicle via the front cover 12. In this embodiment, as described above, the protective member 40 covers the main surface 31s as the meta region. This makes it possible to prevent dust and the like from getting between the nanostructures 35, dust and the like from adhering to the nanostructures 35, and scratches on the nanostructures 35, and makes it possible to appropriately adjust the divergence angle of the light L from the light source unit 20.

[0085] The ribs 42 of the protective member 40 may be provided with communication parts such as holes that connect the closed space 45 with the outside. However, from the viewpoint of preventing dust and the like from entering between the nanostructures 35 and preventing dust and the like from adhering to the nanostructures 35, it is preferable that the protective member 40 does not have such holes.

[0086] Furthermore, the protective member 40 may be in contact with the nanostructures 35. For example, as shown in FIG. 9, the main body 41 of the protective member 40 may fill the spaces between the nanostructures 35. FIG. 9 is a cross-sectional view that shows a schematic view of the protective member 40 and the metalens 30 according to the first modified example, and shows a schematic view of a portion of a cross section in the thickness direction of the protective member 40 and the metalens 30. For ease of viewing, in FIG. 9, only one nanostructure 35 is labeled with a reference symbol, and the reference symbols of the other nanostructures 35 are omitted. In this case, the refractive index of the protective member 40 is made lower than the refractive index of the metalens 30. Even with this configuration, the divergence angle of the light L can be adjusted by the metalens 30.

[0087] Fifth embodiment Next, a fifth embodiment of the present invention will be described. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified. In this embodiment, the configuration of the metalens 30 is different from that of the first embodiment.

[0088] In the metaregion of the metalens 30 of this embodiment, the arrangement of the multiple cells 33 and the size and shape of the nanostructures 35 in each cell 33 are adjusted to change the phase distribution of the light L passing through the metaregion so as to generate coma aberration. Coma aberration is an aberration in which a point image on the image plane is not focused at a single point, but is focused as if spreading out and leaving a comet-like tail. Due to coma aberration, the light on the image plane does not diffuse radially from the point image to the periphery of the point image, but rather extends in a certain direction from the point image. This can be understood as the divergence angle of light being widened by coma aberration.

[0089] The meta region of this embodiment widens the divergence angle of the light L passing through the meta region due to the coma aberration, compared to when the above-mentioned coma aberration does not occur. Due to the widening of the divergence angle of the light L, the light distribution pattern formed by the light L passing through the meta region is projected outside the vehicle lamp 1 in a wider state compared to when the coma aberration does not occur.

[0090] Fig. 10 is a diagram showing low beam light distribution patterns formed on a virtual vertical screen located 25 m ahead of the left and right vehicle lamps 1 in this embodiment. In Fig. 10, a light distribution pattern 70 projected from a metalens 30 in which coma aberration occurs is shown by a solid line. Also, in Fig. 10, a light distribution pattern 80 projected from a metalens in which coma aberration does not occur is shown by a dashed line.

[0091] 10, in order to clarify the light distribution patterns 70 and 80, the upper and lower ends of the light distribution pattern 80 are illustrated inside the upper and lower ends of the light distribution pattern 70, but the upper and lower ends of the light distribution pattern 80 are located at the same positions as the upper and lower ends of the light distribution pattern 70. The centers of the light distribution patterns 70 and 80 are located at the same positions.

[0092] In FIG. 10, S indicates a horizontal line, C indicates a reference axis that passes through the center of the light distribution pattern 70 in the left-right direction and extends from the front to the rear of the vehicle perpendicular to the light distribution pattern 70, and V indicates a vertical line perpendicular to the reference axis C. The light distribution pattern 70 has cutoff lines CL1, CL2, and CL3 at the upper end. The cutoff line CL1 is provided on the opposite side of the cutoff line CL3 with respect to the cutoff line CL2. The intersection of the cutoff lines CL1 and CL2 is called the elbow point EP. The elbow point EP is located below the horizontal line S and on the vertical line V. The elbow point EP may be located below the horizontal line S and in the vicinity of the vertical line V. The cutoff line CL1 extends horizontally from the elbow point EP to the right side, which is one side of the left-right direction of the vehicle. The cutoff line CL2 extends from the elbow point EP diagonally upward to the left in the up-down-left-right direction of the vehicle. The end of the cutoff line CL2 on the opposite side to the elbow point EP side is located above the horizontal line S. The cutoff line CL3 extends horizontally from the end of the cutoff line CL2 to the left in the left-right direction of the vehicle. As the light amount distribution of the light distribution pattern 70, the light amount is greatest in the hot zone HZL located in the vicinity of the elbow point EP, and gradually decreases with increasing distance from the hot zone HZL.

[0093] The meta region of this embodiment changes the phase distribution of the light L passing through the meta region so that coma aberration occurs, which stretches a point image in the light distribution pattern 70 from the inside of the light distribution pattern 70 to the outside of the light distribution pattern 70 in the left-right direction of the light distribution pattern 70. As a result, the meta region of this embodiment widens the divergence angle of the light L in the left-right direction of the light distribution pattern 70 formed by the light L due to coma aberration compared to when coma aberration does not occur, and the light distribution pattern 70 is wider in the left-right direction of the light distribution pattern 70 than the light distribution pattern 80. Of the light distribution pattern 70, a part of the light distribution pattern 70 between the V line and the left end of the light distribution pattern 70 is set as region 70a, and the remaining part of the light distribution pattern 70 between the V line and the right end of the light distribution pattern 70 is set as region 70b. When the metalens 30 is viewed from the vertical direction, the meta region widens the divergence angle of the light L forming region 70a in the left direction from the reference axis C of the light distribution pattern 70 due to coma aberration. Furthermore, when the metalens 30 is viewed in the vertical direction, the metaregion causes the divergence angle of the light L forming the region 70b to expand to the right from the reference axis C of the light distribution pattern 70 by coma aberration. As a result, the light distribution pattern 70 becomes a light distribution pattern in which the left end of the light distribution pattern 80 in the region 70a expands to the left side, which is the outside, and the right end of the light distribution pattern 80 in the region 70b expands to the right side, which is the outside. The metaregion makes the divergence angle of the light L forming the region 70a and expanding to the left equal to the divergence angle of the light L forming the region 70b and expanding to the right. As a result, the amount of expansion at the right end and the left end of the light distribution pattern 70 can be the same, which can make the design of the metalens 30 easier than when the amounts of expansion are not the same.

[0094] As described above, the meta region of this embodiment changes the phase distribution of the light L passing through the meta region so that coma aberration occurs, and widens the divergence angle of the light L passing through the meta region in the left-right direction of the light distribution pattern 70 compared to when coma aberration does not occur.

[0095] In the metalens 30, even if coma aberration does not occur, the divergence angle of the light L can be widened by adjusting the arrangement of the multiple cells 33 and the size and shape of the nanostructures 35 in each cell 33. However, in the meta region of this embodiment, even if the divergence angle is the same as the widened divergence angle when coma aberration does not occur, the divergence angle can be further widened in the left-right direction due to the elongation of the light L caused by the coma aberration. Therefore, according to the vehicular lamp 1 of this embodiment, the light distribution pattern 70 can be wider in the left-right direction than the light distribution pattern projected from the metalens 30 in which the divergence angle of the light L is widened without the occurrence of coma aberration.

[0096] In addition, generally, the projection lens having a curved surface as described above is designed to suppress coma aberration. Therefore, when a projection lens is used, the spread of the divergence angle of light from the light source unit is suppressed by the projection lens, and the spread of the light distribution pattern projected outside the vehicle lamp is suppressed. In contrast, in the meta region of the metalens 30 configured as the projection lens of this embodiment, the divergence angle of the light L from the light source unit 20 is expanded as described above by generating coma aberration, so that the light distribution pattern 70 can be wider than the light distribution pattern projected from the projection lens.

[0097] Furthermore, in the vehicle lamp of Patent Document 2 described above, both a projection lens and an additional lens are used to widen the light distribution pattern. However, in the metalens 30 of the present embodiment, compared to a case in which the light distribution pattern is widened by a projection lens and a lens separate from the projection lens, there is no need to adjust the relative position between the projection lens and the lens, and the number of parts can be reduced, and the weight of the vehicle lamp 1 can be reduced. In addition, compared to a case in which the divergence angle of light is widened by the above-mentioned projection lens and the above-mentioned separate lens, in the vehicle lamp 1 of the present embodiment, the divergence angle of light L can be widened with a single metalens 30, allowing for miniaturization.

[0098] Furthermore, the amount of spread of the light distribution pattern 70 is adjusted by the amount of spread of the divergence angle of the light L, and the amount of spread of the divergence angle is adjusted by the above-mentioned elongation of the light L, which is the degree of coma aberration, and the elongation of the light L is adjusted by the arrangement of the multiple cells 33 and the size and shape of the nanostructures 35 in each cell 33. Because the degree of freedom in the design of the metalens 30 is thus increased, in the vehicle lamp 1 of the present embodiment, the amount of spread of the light distribution pattern 70 can be more easily controlled than in a projection lens in which coma aberration unintentionally occurs due to processing precision.

[0099] Even if coma aberration is intentionally generated in the projection lens, the degree of freedom in the spread of the light distribution pattern is limited due to a trade-off between the shape of the projection lens and the light amount distribution in the light distribution pattern projected by the projection lens, etc. However, in the vehicle lamp 1 of this embodiment, by adjusting the degree of coma aberration described above, the degree of freedom in the spread of the light distribution pattern 70 can be improved compared to a projection lens that intentionally generates coma aberration.

[0100] Furthermore, even if coma aberration occurs in the projection lens, the divergence angle of the light L does not necessarily spread in the left-right direction away from the reference axis C of the light distribution pattern 70, and the light distribution pattern does not necessarily spread easily in the left-right direction. However, in the vehicle lamp 1 of this embodiment, the light distribution pattern 70 can easily spread in the left-right direction by adjusting the arrangement of the multiple cells 33 and the size and shape of the nanostructures 35 in each cell 33. Furthermore, in the vehicle lamp 1 of this embodiment, the metalens 30 can be produced more easily than in the production of a projection lens that intentionally generates coma aberration so that the light distribution pattern 70 spreads in the left-right direction.

[0101] Aberrations that cause light to diverge other than the coma aberration used in the metalens 30 of this embodiment include spherical aberration, astigmatism, and image aberration. With these three aberrations, light on the image plane may be diffused radially from a reference point image to the periphery of the point image. Therefore, with these three aberrations, the blur of the image spreads not only outside the light distribution pattern but also inside the light distribution pattern, as with coma aberration. For this reason, a light distribution pattern that spreads due to any of these three aberrations does not spread efficiently compared to a light distribution pattern that spreads due to coma aberration. In contrast, with the metalens 30 of this embodiment, the divergence angle of light L is spread only in the left-right direction in the direction away from the reference axis C of the light distribution pattern 70 due to coma aberration, so that the light distribution pattern 70 can be spread more efficiently in the left-right direction than with the other three aberrations, and the spreading direction can be specified in one direction. In addition, with the three aberrations, the above-mentioned diffusion may cause a blur in brightness at the left and right ends of the light distribution pattern. In contrast, in the metalens 30 of the present embodiment, the direction in which the light distribution pattern spreads due to coma aberration is controlled to be outside the light distribution pattern in the left-right direction. Therefore, in the metalens 30 of the present embodiment, the amount of light around the left and right edges of the light distribution pattern can gradually decrease from the inside to the outside, and blurring of brightness at the left and right edges of the light distribution pattern can be suppressed compared to the other three aberrations.

[0102] As described above, the light on the image plane extends in a certain direction from the point image due to coma aberration, and the amount of extension of the light corresponds to the spread angle from the point image on the image plane to the outermost angle of the comet-like divergent light spreading from the point image. The amount of light in the light extended due to coma aberration is the largest in the point image, and gradually decreases as it moves away from the point image. In the metalens 30 of this embodiment, the amount of light at the left and right ends of the spreading light distribution pattern 70 gradually decreases from the center side of the light distribution pattern 70 toward the outside, and the occurrence of uneven light distribution at the left and right ends of the light distribution pattern 70 can be suppressed. In addition, from the viewpoint of suppressing uneven light distribution in the light distribution pattern 70, the amount of extension of the light may be about 15% of the spread angle of the light forming the point image on the image plane, and it is very effective if it is 50% of the spread angle.

[0103] Although the light distribution pattern 70 has been described as a light distribution pattern for a low beam, it may be a light distribution pattern for a high beam.

[0104] The meta region may suppress coma aberration in the center of the light distribution pattern 70, and may widen the divergence angle toward the end of the light distribution pattern 70. This maintains the amount of light in the center while ensuring the widening of the driver's field of vision. The meta region may widen one of the divergence angle of the light L forming the region 70a and spreading to the left and the divergence angle of the light L forming the region 70b and spreading to the right. This allows only one of the right end and the left end of the light distribution pattern 70 to widen. The meta region may widen the divergence angle of at least a portion of the light L forming the region 70a and spreading to the left. This allows at least a portion of the left end of the light distribution pattern 70 to widen. The meta region may widen the divergence angle of at least a portion of the light L forming the region 70b and spreading to the right. This allows at least a portion of the right end of the light distribution pattern 70 to widen.

[0105] The fifth embodiment has been used as an example to explain the vehicular lamp 1 including the metalens 30 having a meta region that changes the phase distribution of light L so as to generate coma aberration, but this is not intended to limit the scope of the vehicular lamp 1. Second, third, and fourth modifications of this vehicular lamp 1 will be explained below.

[0106] First, the second modification will be described with reference to Figs. 11 and 12. Fig. 11 is a diagram showing an example of a light distribution pattern in the second modification, and Fig. 12 is a diagram showing another example of a light distribution pattern in the second modification. The meta region of this modification may form the region 70a and make one of the divergence angles of the light L spreading leftward from the reference axis C of the light distribution pattern 70 and the region 70b and the divergence angle of the light L spreading leftward from the reference axis C of the light distribution pattern 70 larger than the other. As a result, one of the spread amount at the right end of the light distribution pattern 70 and the spread amount at the left end of the light distribution pattern 70 becomes larger than the other. For example, if the meta region forms the region 70a and makes the divergence angle of the light L spreading leftward from the reference axis C of the light distribution pattern 70 larger than the divergence angle of the light L spreading rightward from the reference axis C of the light distribution pattern 70, the light distribution pattern 70 spreads wider at the left end than at the right end as shown in Fig. 11. In this case, the irradiation range of the light L to objects such as pedestrians and road signs located on the sidewalk on the driving lane side may be expanded. Also, for example, if the meta region forms the region 70b and the divergence angle of the light L spreading to the right from the reference axis C of the light distribution pattern 70 is made larger than the divergence angle of the light L spreading to the left from the reference axis C of the light distribution pattern 70 forming the region 70a, the light distribution pattern 70 spreads wider to the right end than to the left end as shown in FIG. 12. In this case, the irradiation range of the light L to objects such as pedestrians located on the sidewalk on the oncoming lane side may be expanded. Therefore, the driver of the vehicle may be able to more easily view objects located on the side where the light distribution pattern spreads.

[0107] Next, the third modified example will be described with reference to FIG. 13. FIG. 13 is a diagram showing an example of a light distribution pattern in the third modified example. A light distribution pattern 70 in this modified example is formed by overlapping a light distribution pattern 71 projected from the left vehicle lamp 1 and a light distribution pattern 73 projected from the right vehicle lamp 1. In order to make the light distribution patterns 71 and 73 easier to see, the light distribution pattern 71 is hatched diagonally upward to the left, and the light distribution pattern 73 is hatched diagonally upward to the right. The left end of the light distribution pattern 71 is located outside the left end of the light distribution pattern 73. Also, the right end of the light distribution pattern 73 is located outside the right end of the light distribution pattern 71.

[0108] The light distribution pattern 80, like the light distribution pattern 70, is formed by overlapping light distribution patterns projected from the left and right vehicle lamps 1. In order to make it easier to distinguish from the light distribution patterns 71 and 73, the light distribution pattern 80 is not hatched.

[0109] The meta region of the left vehicular lamp 1 widens the divergence angle of the light L to the left from the optical axis, which is the direction away from the reference axis C of the light distribution pattern 70, by coma aberration. As a result, the left end of the light distribution pattern 71 widens further to the left than the left end of the light distribution pattern 80. Also, the meta region of the right vehicular lamp 1 widens the divergence angle of the light L to the right from the optical axis, which is the direction away from the reference axis C of the light distribution pattern 70, by coma aberration. As a result, the left end of the light distribution pattern 73 widens further to the right than the right end of the light distribution pattern 80.

[0110] In this way, even when light distribution pattern 70 is formed by overlapping light distribution patterns 71, 73 projected from left and right vehicle lamps 1, respectively, it is possible to widen light distribution pattern 70 to the left. Furthermore, in this modification, the left-side spread of the light distribution pattern in the left direction can be adjusted, for example, by replacing left-side metalens 30 with another left-side metalens 30 having a different degree of coma aberration from the left-side metalens 30 before replacement.

[0111] Next, the fourth modified example will be described with reference to FIG. 14. FIG. 14 is a diagram showing an example of a light distribution pattern in the fourth modified example. In FIG. 14, S1 is a line parallel to the horizontal line S and passes through the center of the light distribution pattern 70. Of the light distribution pattern 70, a part of the light distribution pattern 70 between the S1 line and the upper end of the light distribution pattern 70 is set as the region 70c, and the remaining part of the light distribution pattern 70 between the S1 line and the lower end of the light distribution pattern is set as the region 70d. The light distribution pattern 70 is for low beam, and the position of the cut line needs to be fixed. For this reason, when the metalens 30 is viewed from the horizontal direction, the meta region does not widen the divergence angle of the light L forming the region 70c in the upward direction from the optical axis, which is the direction away from the reference axis C of the light distribution pattern 70, due to coma aberration, but widens the divergence angle of the light L forming the region 70d in the downward direction from the optical axis, which is the direction away from the reference axis C of the light distribution pattern 70, due to coma aberration. As a result, the light distribution pattern 70 becomes a light distribution pattern in which the lower end of the light distribution pattern 80 spreads downward, that is, outward, in the region 70d. For example, when the light distribution pattern 70 is a light distribution pattern for high beam, the meta region may spread the divergence angle of the light L forming the region 70c upward from the optical axis, which is a direction away from the reference axis C of the light distribution pattern 70, by coma aberration when the metalens 30 is viewed from the horizontal direction. As a result, the light distribution pattern 70 becomes a light distribution pattern in which the upper end of the light distribution pattern 80 spreads upward, that is, outward, in the region 70c. In this way, the meta region changes the phase distribution of the light L passing through the meta region so that coma aberration occurs that extends the point image in the light distribution pattern 70 from the inside of the light distribution pattern 70 to the outside of the light distribution pattern 70 in the vertical direction of the light distribution pattern 70. As a result, the meta region widens the divergence angle of the light L in the vertical direction of the light distribution pattern in a direction away from the reference axis C of the light distribution pattern 70 compared to when no coma aberration occurs, and also widens the light distribution pattern 70 in the vertical direction, which is the height direction of the light distribution pattern, compared to the light distribution pattern 80. In this case, it may become easier for the driver of the vehicle to visually recognize objects such as guide signs and road surfaces.

[0112] In addition, the meta region widens the divergence angle of the light L that forms the end side of the light distribution pattern 70 in the left-right direction and spreads in the left-right direction from the reference axis C of the light distribution pattern 70, more than the divergence angle of the light L that forms the end side of the light distribution pattern 70 in the up-down direction and spreads in the up-down direction from the reference axis C of the light distribution pattern 70. As a result, the amount of spread at each of the left and right ends of the light distribution pattern 70 is greater than the amount of spread at the bottom end of the light distribution pattern 70, and the light distribution pattern 70 spreads more in the left-right direction than in the up-down direction of the light distribution pattern 70 without changing the amount of light emitted from the metalens 30. As a result, the light distribution pattern can ensure that the driver's field of vision is wider in the left-right direction than in the up-down direction. In addition, compared to a case in which the amount of spread at each of the left and right ends of the light distribution pattern 70 is not greater than the amount of spread at the bottom end of the light distribution pattern 70, the driver of the vehicle can more easily see pedestrians and objects such as road signs.

[0113] The meta region does not need to increase the divergence angle of the light L forming the lower end side of the light distribution pattern 70, and may increase the divergence angle of the light L forming the upper end side of the light distribution pattern 70. Alternatively, the meta region may increase the divergence angle of the light L forming the end side of the light distribution pattern 70 in the vertical direction more than the divergence angle of the light L forming the end side of the light distribution pattern 70 in the horizontal direction. As a result, the light distribution pattern 70 spreads more in the vertical direction than in the horizontal direction of the light distribution pattern 70.

[0114] Sixth embodiment Next, a sixth embodiment of the present invention will be described. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified. In this embodiment, the configuration of the metalens 30 is different from that of the first embodiment.

[0115] As shown in FIG. 1, for example, when a vehicle is traveling uphill during the day, light such as sunlight may enter the inside of the housing 10 of the vehicle lamp 1 from the outside of the vehicle lamp 1 through the front cover 12. The light that enters the inside of the housing 10 enters the main surface 32s of the metalens 30, exits from the main surface 31s toward the light source unit 20, and travels in the opposite direction to the light L from the light source unit 20 to be concentrated at the light source unit 20. The concentration of light may cause deterioration of the light source unit 20. The meta region of this embodiment suppresses the concentration of light by a bending force, and the bending force will be described below. In the following, the longest wavelength of visible light contained in the light is 660 nm, the shortest wavelength of infrared light contained in the light is 1000 nm, and the ratio of the wavelengths of the respective lights in this case is 1:1.5.

[0116] The bending force refers to the force with which a refractive lens or meta-region bends the light passing through it. The smaller the bending force, the smaller the bending angle of the light passing through it, and the less the light is focused.

[0117] Next, the bending power of one refractive lens will be explained. The main materials of refractive lenses include acrylic and polycarbonate. The refractive index of a refractive lens made of acrylic is 1.489 for visible light and 1.483 for infrared light. The refractive index of a refractive lens made of polycarbonate is 1.579 for visible light and 1.568 for infrared light.

[0118] Since the focal length of a refractive lens is inversely proportional to the "refractive index - 1", the bending power of the refractive lens is proportional to the "refractive index - 1". Therefore, in a refractive lens made of acrylic, if the bending power of a refractive lens that bends visible light is set to 1, the bending power of a refractive lens that bends infrared light is approximately 0.98. In addition, in a refractive lens made of polycarbonate, if the bending power of a refractive lens that bends visible light is set to 1, the bending power of a refractive lens that bends infrared light is approximately 0.98.

[0119] Therefore, whether it is acrylic or polycarbonate, the bending force of the refractive lens that bends infrared light is approximately 0.98 times that of the refractive lens that bends visible light. In this case, since the bending force of the refractive lens that bends infrared light is approximately the same as that of the refractive lens that bends visible light, the bending angle of infrared light is approximately the same as that of visible light, and the focal length of the refractive lens that bends infrared light is approximately the same as that of visible light. Therefore, the refractive lens makes it easier to focus infrared light.

[0120] Next, the bending force of the meta-region will be described. The phase distribution of light passing through the meta-region is changed by the meta-region as described above. Since the phase represents the advance or delay of the wavefront of the light, the light given the phase distribution has a tilt in the wavefront. Since the light travels in a direction perpendicular to the wavefront, the wavefront of the light whose phase has been modulated in the meta-region by the above effect is tilted in a direction different from the original traveling direction, and the traveling direction of the light is bent. Therefore, the bending force of the meta-region that bends the light passing through the meta-region is roughly proportional to the product of the phase modulation amount of the light and the wavelength of the light. As described above, the meta-region changes the phase distribution of the light passing through the meta-region. This phase distribution changes depending on the arrangement of the multiple cells 33 and the size and shape of the nanostructure 35 in each cell 33. By these adjustments, the meta-region changes the phase distribution of the light passing through the meta-region. In addition, the meta-region changes the phase modulation amount of the light by the change. In the meta region of this embodiment, the ratio of the phase modulation amount of visible light to the phase modulation amount of infrared light is 4:1 by the above adjustment, and the ratio of the longest wavelength of visible light to the shortest wavelength of infrared light is 1:1.5 as described above. Therefore, in this case, the ratio of the bending force of the meta region that bends visible light to the bending force of the meta region that bends infrared light is 1:0.3.

[0121] In this way, the meta region changes the phase distribution of the light passing through the meta region by the above adjustment, and this change changes the amount of phase modulation of the light, which makes the bending force of the meta region bending the infrared light passing through the meta region smaller than the bending force of the meta region bending the visible light passing through the meta region. When the bending force of the meta region bending the infrared light becomes smaller than the bending force of the meta region bending the visible light, the bending angle of the infrared light becomes smaller than the bending angle of the visible light, so the meta region can suppress the focusing of the infrared light. Therefore, the meta region focuses the visible light on the light source unit 20 and suppresses the focusing of the infrared light to transmit the infrared light.

[0122] Next, a comparison will be made between the bending force of the metaregion that bends infrared light and the bending force of the refractive lens that bends infrared light. When comparing the two based on the bending force of each of the metaregions that bend visible light, the bending force of the metaregion that bends infrared light is smaller than the bending force of the refractive lens that bends infrared light due to the above adjustment. Therefore, the bending angle of infrared light by the metaregion is smaller than the bending angle of infrared light by the refractive lens. If the focal length of the refractive lens that bends visible light is assumed to be 50 mm, the focal length of the refractive lens that bends infrared light is shifted by approximately 0.1 mm from the focal length of the refractive lens that bends visible light due to the above bending force ratio of the refractive lens. In contrast, if the focal length of the metalens 30 including the metaregion that bends visible light is assumed to be 50 mm as above, the focal length of the metalens 30 including the metaregion that bends infrared light is shifted by approximately 100 mm from the focal length of the metalens 30 including the metaregion that bends visible light due to the above bending force ratio of the metaregion. Therefore, if the meta region has a smaller bending force for bending infrared light than a refractive lens, the bending angle of the infrared light by the meta region will be smaller than the bending angle of the infrared light by a refractive lens, and the meta region can suppress the concentration of infrared light more than a refractive lens.

[0123] Note that even if the focal length of metalens 30 for infrared light deviates from the focal length of metalens 30 for visible light by only about 10% of the focal length, the metaregion can suppress the focusing of infrared light. In this case, the ratio of the bending force of the metaregion that bends visible light to the bending force of the metaregion that bends infrared light is approximately 1:0.9, that is, the bending force of the metaregion that bends infrared light is approximately 0.9 times that of the metaregion that bends visible light. Below, we will explain the ratio of the phase modulation amount of visible light to the phase modulation amount of infrared light when the ratio of the bending force of the metaregion that bends visible light to the bending force of the metaregion that bends infrared light is approximately 1:0.9.

[0124] Here, the ratio of the phase modulation amount of visible light to the phase modulation amount of infrared light is 1:X. The ratio of the wavelengths of visible light and infrared light is 1:1.5 as described above. The ratio of the bending force of the meta region that bends visible light to the bending force of the meta region that bends infrared light is preferably about 1:0.9 as described above. As described above, the bending force of the meta region that bends each of visible light and infrared light is approximately proportional to the product of the phase modulation amount and the wavelength. Therefore, X is 0.6, and the phase modulation amount of infrared light is 0.6 times the phase modulation amount of visible light. Since the bending force of the meta region that bends infrared light is preferably less than 0.9 times the bending force of the meta region that bends visible light, the phase modulation amount of infrared light is preferably less than 0.6 times the phase modulation amount of visible light.

[0125] As described above, the bending force of the refractive lens that bends infrared light is approximately 0.98 times that of the refractive lens that bends visible light, and the bending force of the meta region that bends infrared light is less than 0.9 times that of the meta region that bends visible light. When comparing the bending force of the meta region that bends infrared light and the bending force of the refractive lens that bends infrared light based on the respective bending forces that bend visible light, the bending force of the meta region that bends infrared light is smaller than the bending force of the refractive lens that bends infrared light. Therefore, the meta region can suppress the collection of infrared light more than the refractive lens.

[0126] 15 is a diagram showing the relationship between the diameter of nanostructure 35 and the phase modulation amount of visible light with a longest wavelength of 660 nm and infrared light with a shortest wavelength of 1000 nm. The solid line shows the relationship between the diameter of nanostructure 35 and the phase modulation amount of visible light, and the dashed line shows the relationship between the diameter of nanostructure 35 and the phase modulation amount of infrared light.

[0127] In order for the metalens 30 to function as a lens for visible light and thereby focus visible light, it is important that the phase modulation amount of visible light is in the range of 0-2π (rad). For this purpose, the shape of the nanostructure 35 is cylindrical, and the diameter range of the cylindrical nanostructure 35 may be a diameter corresponding to this range, and is preferably, for example, from 0 nm to 250 nm. In this embodiment, the diameter range of the nanostructure 35 is more preferably, for example, from 100 nm to 250 nm, and a plurality of nanostructures 35 having diameters within this range are arranged. In the range of the phase modulation amount of visible light, the phase modulation amount of infrared light is 0.5π radians. Therefore, the metaregion suppresses the focusing of infrared light and transmits infrared light.

[0128] When the nanostructure 35 has a cylindrical shape, the longer the wavelength of the focused light, the smaller the slope of the graph shown in FIG. 15 becomes, and therefore the range of the diameter of the nanostructure 35 becomes wider.

[0129] As described above, the metaregion of this embodiment changes the phase distribution of the light passing through the metaregion, making the bending force of the metaregion bending the infrared light contained in the light passing through the metaregion smaller than the bending force of the metaregion bending the visible light contained in the light passing through the metaregion.

[0130] In the vehicle lamp 1 of this embodiment, as described above, the meta region changes the phase distribution of the light passing through the meta region. This phase distribution changes depending on the arrangement of the multiple cells 33 and the size and shape of the nanostructure 35 in each cell 33. For this reason, the meta region adjusts these to change the phase distribution of the light passing through the meta region, and makes the bending force of the meta region that bends the infrared light contained in the light smaller than the bending force of the meta region that bends the visible light contained in the light. The smaller the bending force, the smaller the bending angle of the light passing through the meta region, and the more the focusing of the light is suppressed. Therefore, for example, even if sunlight enters the inside of the housing 10 of the vehicle lamp 1 from the outside of the vehicle lamp 1 through the front cover 12, in this vehicle lamp 1, the bending angle of the infrared light contained in the sunlight is smaller than the bending angle of the visible light in the sunlight due to the bending force, so that the meta region can suppress the focusing of the infrared light proceeding to the light source unit 20 compared to the projection lens. When the focusing of the infrared light is suppressed, the deterioration of the light source unit 20 due to the focusing of the infrared light can be suppressed compared to the projection lens.

[0131] Furthermore, when the deterioration of the light source unit 20 is suppressed, the influence of the deterioration of the light source unit 20 on the light L emitted from the light source unit 20 is suppressed, and a predetermined light distribution pattern can be projected.

[0132] Furthermore, by making the nanostructure 35 cylindrical, even if the visible light from the light source unit 20 is randomly polarized, the visible light can be efficiently bent.

[0133] The sixth embodiment has been used as an example to explain the vehicular lamp 1 including the metalens 30 having a metaregion in which the bending force for bending infrared light is smaller than the bending force for bending visible light, but the vehicular lamp 1 is not limited to this. Modifications of the sixth embodiment will be explained below.

[0134] In the sixth embodiment of the vehicle lamp 1, sunlight is used as the light that enters the vehicle lamp 1 from the outside, but the light is not limited to sunlight and may be infrared light and visible light that enter the vehicle lamp 1 from the outside. As an example of a wavelength ratio of 1:1.5, the longest wavelength of visible light is 660 nm and the shortest wavelength of infrared light is 1000 nm, but as long as the ratio is 1:1.5, the wavelengths of the visible light and infrared light are not particularly limited.

[0135] The light distribution pattern projected from the vehicle lamp 1 may be a light distribution pattern for a low beam or a light distribution pattern for a high beam.

[0136] Seventh embodiment Next, a seventh embodiment of the present invention will be described. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified. In this embodiment, the configurations of the light source unit 20 and the metalens 30 are different from those in the first embodiment.

[0137] FIG. 16 is a diagram similar to FIG. 1 showing a vehicle lamp in this embodiment. FIG. 17 is a diagram showing the spectral distribution of the light emitted from the light source unit 20 in this embodiment and the light transmittance distribution of the metalens 30. In FIG. 17, the horizontal axis is the wavelength, the first vertical axis is the relative intensity based on the maximum intensity, and the second vertical axis is the relative transmittance based on the maximum transmittance. In FIG. 17, the spectral distribution is shown by a thin line, and the transmittance distribution is shown by a thick line. In this embodiment, the wavelength band of the light L emitted from the light source unit 20 is approximately 380 nm to 780 nm. As shown in FIG. 17, the spectral distribution 90 of this light L has four peaks 91, 92, 93, and 94. The wavelengths 91w, 92w, 93w, and 94w in the peaks 91, 92, 93, and 94 are longer in the order of wavelength 91w, wavelength 92w, wavelength 93w, and wavelength 94w. The wavelength 91w is approximately 410 nm, the wavelength 92w is approximately 460 nm, the wavelength 93w is approximately 530 nm, and the wavelength 94w is approximately 620 nm. Therefore, among the wavelengths 91w, 92w, 93w, and 94w in the multiple peaks 91, 92, 93, and 94, the wavelength 91w is the shortest and the wavelength 94w is the longest. Furthermore, the wavelengths 91w, 92w, 93w, and 94w in these peaks 91, 92, 93, and 94 are included in the wavelength band of visible light. The spectral distribution 90 may have a peak that is not included in the wavelength band of visible light. Furthermore, the number of peaks in the spectral distribution 90 is not limited, and for example, the spectral distribution 90 may not have a peak. Furthermore, since the light L emitted from the light source unit 20 is emitted from a plurality of light emitting elements 21, the spectral distribution of the light emitted from each light emitting element 21 is approximately the same as the spectral distribution 90 shown in FIG.

[0138] For example, when a vehicle is traveling uphill during the day, sunlight L2 may enter the lamp chamber R through the front cover 12, pass through the metalens 30, and be irradiated to the light source unit 20, as shown in Fig. 16. In this embodiment, the metalens 30 reduces the divergence angle of light L from the light source unit 20 that passes through the metalens 30. For this reason, the sunlight L2 that passes through the metalens 30 is concentrated and irradiated to the light source unit 20.

[0139] Fig. 18 is a diagram that shows a schematic representation of the spectral distribution of sunlight L2 near the earth's surface, and the optical transmittance distribution of the metalens 30 of this embodiment. In Fig. 18, the horizontal axis is wavelength, the vertical axis is relative intensity with respect to the maximum intensity, and the second vertical axis is relative transmittance with respect to the maximum transmittance. In Fig. 18, the spectral distribution is shown by a thin line, and the transmittance distribution in the range from 300 nm to 2500 nm is shown by a thick line. As shown in Fig. 18, sunlight L2 contains infrared light as well as visible light.

[0140] In addition, in a metalens having a metaregion in which cells including nanostructures are arranged, a phenomenon may occur in which the transmittance of light of a specific wavelength becomes extremely lower than the transmittance of light of other wavelengths, and it is known that there are a plurality of such specific wavelengths. These specific wavelengths are wavelengths at which the non-transmittance of light in the metalens is at its peak, and are called resonant wavelengths. These resonant wavelengths are determined according to the size and shape of the nanostructure in each cell, the refractive index of the material constituting the nanostructure, and the like. In this embodiment, as shown in FIG. 18, among the multiple resonant wavelengths in the metalens 30, the longest resonant wavelength 30w1 and the second longest resonant wavelength 30w2 are in the range of 800 nm or more and less than 2400 nm, and the second longest resonant wavelength 30w2 is in the range of 800 nm or more and less than 900 nm. Specifically, the resonant wavelength 30w1 is approximately 1700 nm, and the resonant wavelength 30w2 is approximately 850 nm. Moreover, the third longest resonant wavelength 30w3 is approximately 425 nm. In addition, dashed lines SL1, SL2, and SL3 indicating these resonance wavelengths 30w1, 30w2, and 30w3 are shown in FIG. 18. Also, dashed line SL3 indicating the resonance wavelength 30w3 is shown in FIG. 17. As shown in FIG. 17, the resonance wavelength 30w3 is included in the wavelength band of the light L emitted from the light source unit 20, and the light L from the light source unit 20 includes light having the same wavelength as the resonance wavelength 30w3. However, this resonance wavelength 30w3 is different from the wavelengths 91w, 92w, 93w, and 94w of the peaks 91, 92, 93, and 94 in the spectral distribution 90 of the light L. Therefore, all of the multiple resonance wavelengths in the metalens 30 are different from the wavelengths of these peaks. Also, this resonance wavelength 30w3 is a wavelength between the wavelengths 91w and 92w of the peaks 91 and 92 adjacent to each other. It is sufficient that at least one resonance wavelength in the metalens 30 is 800 nm or more and less than 2400 nm. For example, the longest resonant wavelength may be resonant wavelength 30w2, and the second longest resonant wavelength may be resonant wavelength 30w3.

[0141] As described above, in the vehicular lamp 1 of the present embodiment, at least one resonant wavelength in the metalens 30 is equal to or greater than 800 nm and less than 2400 nm. Furthermore, as shown in FIG. 18, sunlight near the ground generally contains light in the wavelength band from 800 nm to 2400 nm. For this reason, according to the vehicular lamp 1 of the present embodiment, when the sunlight L2 passes through the metalens 30 and is irradiated onto the light source unit 20, the amount of light of the sunlight L2 with wavelengths from 800 nm to 2400 nm irradiated onto the light source unit 20 can be reduced compared to when the metalens 30 is used as a projection lens. Therefore, according to the vehicular lamp 1 of the present embodiment, the amount of heating of the light source unit 20 by the sunlight L2 can be reduced compared to the above case, and deterioration of the light source unit 20 due to the sunlight L2 can be suppressed.

[0142] In the vehicle lamp 1 of this embodiment, the resonant wavelength 30w2 is included in the range of 800 nm or more and less than 900 nm. As shown in FIG. 18, the intensity of the sunlight L2 near the ground generally tends to decrease as the wavelength becomes longer in the wavelength band of 800 nm or more. The spectral distribution 100 of the sunlight L2 has multiple valleys where the intensity suddenly decreases. The minimum intensity in the valley is, for example, 50% or less of the intensity in the vicinity of the valley. Such valleys tend not to be located in the range of 800 nm or more and less than 900 nm. For this reason, the above-mentioned configuration makes it easy to reduce the amount of heating of the light source unit 20 by the sunlight L2 when the sunlight L2 passes through the metalens 30 and is irradiated to the light source unit 20. Multiple resonant wavelengths may be included in the range of 800 nm or more and less than 900 nm, or the resonant wavelength may not be included in this range.

[0143] In the vehicle lamp 1 of this embodiment, the spectral distribution 90 of the light L emitted from the light source unit 20 has four peaks 91, 92, 93, and 94. The multiple resonant wavelengths are different from the wavelengths 91w, 92w, 93w, and 94w of the peaks 91, 92, 93, and 94. The light having wavelengths at the peaks 91, 92, 93, and 94 of the spectral distribution 90 tends to greatly affect the color tone of the light emitted from the vehicle lamp. For this reason, the vehicle lamp 1 of this embodiment can suppress a decrease in the transmittance of the metalens 30 of light having a wavelength that greatly affects the color tone of the emitted light, and can emit light of a desired color tone.

[0144] In addition, from the viewpoint of emitting light of a desired color tone, the spectral distribution 90 may have multiple peaks, and the multiple resonant wavelengths may be different from the wavelengths of the multiple peaks. For example, the multiple resonant wavelengths may be included in the wavelength band of the light L emitted from the light source unit 20. In addition, in this embodiment, the resonant wavelength 30w3 included in the wavelength band of the light L from the light source unit is a wavelength between the wavelengths 91w and 92w of the peaks 91 and 92 adjacent to each other. In such a case, it is preferable that the resonant wavelength 30w3 is the same as the wavelength of the light L having the minimum intensity between the peaks 91 and 92 adjacent to each other. By adopting such a configuration, a decrease in the amount of emitted light can be suppressed compared to a case where the wavelength of the light excluding the light having the minimum intensity between the peaks 91 and 92 is the same as the resonant wavelength 30w3.

[0145] In addition, from the viewpoint of suppressing a decrease in the amount of emitted light, it is preferable that the ratio of the intensity of the light of the resonance wavelength 30w3 in the light L from the light source unit 20 to the maximum intensity in the entire spectral distribution 90 is 0.1 or less. With such a configuration, it is possible to suppress a decrease in the amount of emitted light compared to when this ratio exceeds 0.1. Also, with such a configuration, it is possible to easily emit light of a desired color tone compared to when this ratio exceeds 0.1. It is more preferable that this ratio is zero. However, this ratio may be greater than 0.1. In addition, from the viewpoint of suppressing a decrease in the amount of emitted light, it is preferable that the ratio of the amount of light of the resonance wavelength 30w3 in the light L from the light source unit 20 to the amount of the entire light L from the light source unit 20 is less than 4%.

[0146] Furthermore, in the vehicle lamp 1 of the present embodiment, as described above, the metalens 30 reduces the divergence angle of the light L from the light source unit 20 that passes through the metalens 30. For this reason, the sunlight L2 that passes through the metalens 30 is concentrated and irradiated onto the light source unit 20, so there is a higher possibility that the light source unit 20 will deteriorate compared to when the metalens 30 increases the divergence angle of the light L from the light source unit 20. For this reason, the vehicle lamp 1 of the present embodiment is particularly useful in cases where the divergence angle of the light L from the light source unit 20 is reduced.

[0147] Moreover, the vehicle lamp 1 of the present embodiment includes a housing 10 that houses the light source unit 20 and the metalens 30. In such a vehicle lamp 1, depending on the angle of incidence of the sunlight L2 on the metalens 30, the sunlight L2 that has passed through the metalens 30 may be irradiated onto the inner surface of the housing 10. According to the vehicle lamp 1 of the present embodiment, when the sunlight L2 passes through the metalens 30 and is irradiated onto the housing 10, the amount of light with wavelengths from 800 nm to 2400 nm of the sunlight L2 that is irradiated onto the inner surface of the housing 10 can be reduced compared to when the metalens 30 is used as a projection lens.

[0148] The seventh embodiment has been used as an example to describe a vehicle lamp 1 including a metalens 30 having at least one resonant wavelength that is equal to or greater than 800 nm and less than 2400 nm. However, such a vehicle lamp 1 is not limited to this. Modifications of the seventh embodiment will be described below.

[0149] For example, the seventh embodiment has been described taking as an example the metalens 30 in which the multiple resonant wavelengths include a resonant wavelength 30w3 that is included in the wavelength band of the light L emitted from the light source unit 20. However, all of the multiple resonant wavelengths in the metalens 30 do not have to be included in the wavelength band of the light L emitted from the light source unit 20. In other words, the light L emitted from the light source unit 20 does not have to include all of the multiple resonant wavelengths in the metalens 30. With this configuration, it is possible to emit light of a desired color tone, compared to the case in which at least one resonant wavelength is included in the wavelength band of the light L emitted from the light source unit 20.

[0150] Furthermore, in the seventh embodiment, a metalens 30 in which all of the multiple resonant wavelengths are different from the respective wavelengths of the multiple peaks has been described as an example. However, from the viewpoint of emitting light of a desired color tone, it is sufficient that the multiple resonant wavelengths are different from the respective wavelengths of the multiple peaks, and for example, a specific resonant wavelength may be the same as the wavelength of a certain peak. Note that, from the viewpoint of emitting light of a desired color tone, it is preferable that all of the multiple resonant wavelengths are different from the respective wavelengths of the multiple peaks.

[0151] Furthermore, from the perspective of emitting light of a desired color tone, it is preferable that the light transmittance distribution of the metalens 30 has a relative transmittance of 80% or less based on the maximum transmittance of the light L from the light source unit 20 that passes through the metalens 30, includes a plurality of consecutive resonant wavelength bands that include one resonant wavelength, and at least one of these resonant wavelength bands is different from the wavelengths of the respective peaks. In this case, it is more preferable that all of these resonant wavelength bands are different from the wavelengths of the respective peaks. Note that, if the light transmittance distribution of the metalens 30 has a relative transmittance of 60% or less based on the maximum transmittance of the light L from the light source unit 20 that passes through the metalens 30, and includes a plurality of consecutive resonant wavelength bands that include one resonant wavelength, it is more preferable that at least one of these resonant wavelength bands is different from the wavelengths of the respective peaks. In this case, it is more preferable that all of these resonant wavelength bands are different from the wavelengths of the respective peaks. Furthermore, if the light transmittance distribution of the metalens 30 has a relative transmittance of 40% or less based on the maximum transmittance of light L from the light source unit 20 passing through the metalens 30, and includes a plurality of continuous resonance wavelength bands including one resonance wavelength, it is more preferable that at least one of these resonance wavelength bands is different from each of the wavelengths of the plurality of peaks. In this case, it is more preferable that all of these resonance wavelength bands are different from each of the wavelengths of the plurality of peaks.

[0152] In addition, from the viewpoint of facilitating the emission of light of a desired color tone, unlike the seventh embodiment, for example, the longest resonance wavelength of the metalens may be shorter than the shortest wavelength among the wavelengths at the peak of the spectral distribution of light from the light source unit. In other words, the light source unit and the metalens may be configured so as to be like this. Hereinafter, such a modification will be described with reference to FIG. 19. Note that components that are the same as or equivalent to those in the seventh embodiment will be given the same reference numerals and will not be described again unless otherwise specified. FIG. 19 is a diagram similar to FIG. 17 showing the spectral distribution 90 of light emitted from the light source unit 20 and the light transmittance distribution of the metalens 30 according to the fifth modification. In this modification, the resonance wavelength of the metalens 30 is different from the resonance wavelength in the above embodiment. Also, the spectral distribution 90 is the same as the spectral distribution 90 in the above embodiment, but may be different. Also, the longest resonance wavelength 30w1 of the metalens 30 is included in the wavelength band of the light L from the light source unit 20. However, as described above, the longest resonant wavelength 30w1 is shorter than the shortest wavelength 91w among the wavelengths 91w, 92w, 93w, and 94w of the multiple peaks 91, 92, 93, and 94. Therefore, all of the multiple resonant wavelengths in the metalens 30 are shorter than the wavelength 91w. According to the vehicle lamp 1 of this modification, it is possible to suppress a decrease in the transmittance of light of a wavelength that significantly affects the color tone of the emitted light, compared to a case in which the longest resonant wavelength 30w1 in the metalens 30 is longer than the shortest wavelength 91w. Therefore, according to the vehicle lamp 1 of this modification, it is possible to more easily emit light of a desired color tone, compared to the above case. Note that, from the viewpoint of making it easier to emit light of a desired color tone, the longest resonant wavelength 30w1 in the metalens 30 may be shorter than the shortest wavelength in the wavelength band of the light L from the light source unit 20. Also, in this respect, the longest resonant wavelength 30w1 of metalens 30 may be shorter than the shortest wavelength in the wavelength band of visible light, for example, 380 nm. That is, metalens 30 may be configured so as to be in this manner.

[0153] Eighth embodiment Next, an eighth embodiment of the present invention will be described. Note that components that are the same as or equivalent to those in the first embodiment will be given the same reference numerals and will not be described again unless otherwise specified. In this embodiment, the configurations of the light source unit 20 and the metalens 30 are different from those in the first embodiment.

[0154] FIG. 20 is a diagram that illustrates the spectral distribution of light emitted from the light source unit 20 in this embodiment and the transmittance distribution of light of the metalens 30. In FIG. 20, the horizontal axis is the wavelength, the first vertical axis is the relative intensity based on the maximum intensity, and the second vertical axis is the relative transmittance based on the maximum transmittance. In FIG. 20, the spectral distribution is indicated by a thin line, and the transmittance is indicated by a thick line. As shown in FIG. 20, in this embodiment, the spectral distribution 90 has four peaks 91, 92, 93, and 94. The wavelengths 91w, 92w, 93w, and 94w at the respective peaks 91, 92, 93, and 94 increase in the order of the wavelength 91w, the wavelength 92w, the wavelength 93w, and the wavelength 94w. The wavelength 91w is approximately 410 nm, the wavelength 92w is approximately 460 nm, the wavelength 93w is approximately 530 nm, and the wavelength 94w is approximately 620 nm. Therefore, among the wavelengths 91w, 92w, 93w, and 94w at the multiple peaks 91, 92, 93, and 94, the wavelength 91w is the shortest and the wavelength 94w is the longest. Moreover, the wavelengths 91w, 92w, 93w, and 94w at the peaks 91, 92, 93, and 94 are included in the wavelength band of visible light. Note that the spectral distribution 90 may have a peak that is not included in the wavelength band of visible light. Moreover, since the light L emitted from the light source unit 20 is light emitted from multiple light-emitting elements 21, the spectral distribution of the light emitted from each light-emitting element 21 is approximately the same as the spectral distribution 90 shown in FIG.

[0155] In this embodiment, the shape of nanostructure 35 is cylindrical, and the diameter is smaller than wavelength 94w of peak 94 shown in Fig. 20. Note that as long as the width of nanostructure 35 is smaller than the longest wavelength 94w among the wavelengths of peaks 91, 92, 93, and 94, the shape of nanostructure 35 is not particularly limited.

[0156] As described in the seventh embodiment, the resonant wavelength in the metalens is determined according to the size and shape of the nanostructure in each cell, the refractive index of the material constituting the nanostructure, and the like. In this embodiment, all of the multiple resonant wavelengths in the metalens 30 are different from the wavelengths 91w, 92w, 93w, and 94w at the peaks 91, 92, 93, and 94, respectively. Also, as shown in FIG. 20, among the multiple resonant wavelengths in the metalens 30, the longest resonant wavelength 30w1 is longer than the wavelength 94w, and the second longest resonant wavelength 30w2 is included in the wavelength band of the light L from the light source unit 20. Note that FIG. 20 shows dashed lines SL1 and SL2 indicating these resonant wavelengths 30w1 and 30w2. In this embodiment, the second longest resonant wavelength 30w2 is longer than the shortest wavelength 91w and shorter than the longest wavelength 92w among these wavelengths 91w, 92w, 93w, and 94w. In the case where the multiple resonant wavelengths do not include a resonant wavelength that is longer than the shortest wavelength 91w and shorter than the longest wavelength 94w, the design of the size and shape of the nanostructure 35 in each cell 33, the arrangement of the cells 33, and the like tends to become complicated. For this reason, in this embodiment, it is possible to suppress these designs from becoming complicated. Note that the multiple resonant wavelengths do not need to include a resonant wavelength that is longer than the wavelength 91w and shorter than the wavelength 94w. In addition, in this embodiment, the wavelength of the light from the light source unit 20 that has the smallest intensity between the adjacent peaks 92 and 93 among the peaks 91, 92, 93, and 94 is the same as the second longest resonant wavelength 30w2. Note that the wavelength of the light from the light source unit 20 that has the smallest intensity between the peaks 92 and 93 may be different from this resonant wavelength 30w2. Furthermore, this resonant wavelength 30w2 may be a wavelength between peaks 91 and 92, or may be a wavelength between peaks 93 and 94, and this resonant wavelength 30w2 may be the same as or different from the wavelength of the light from the light source unit 20 that has the smallest intensity between these peaks. Furthermore, the multiple resonant wavelengths in the metalens 30 may include multiple resonant wavelengths that are longer than the shortest wavelength 91w and shorter than the longest wavelength 94w.

[0157] In the light-emitting module of Patent Document 3 described above, the wavelength of the light emitted from the LED and the phosphor can be appropriately selected to adjust the color tone of the emitted light. For this reason, it is considered that by using such a light-emitting module in the light source section of a vehicle lamp, light of a desired color tone can be emitted from the vehicle lamp. In the vehicle lamp 1 of this embodiment, as described above, the spectral distribution 90 of the light emitted from the light source section 20 has multiple peaks 91, 92, 93, and 94. For this reason, according to the vehicle lamp 1 of this embodiment, the color tone of the emitted light can be made to be a desired color tone compared to the case where the spectral distribution 90 has only one peak. In addition, the multiple resonant wavelengths in the metalens 30 of this embodiment are different from the wavelengths 91w, 92w, 93w, and 94w of the multiple peaks 91, 92, 93, and 94, respectively. The light of the wavelengths 91w, 92w, 93w, and 94w of the multiple peaks 91, 92, 93, and 94, respectively, greatly affect the color tone of the light emitted from the vehicle lamp 1. For this reason, according to the vehicle lamp 1 of the present embodiment, it is possible to prevent a decrease in the transmittance through the metalens 30 of light of the wavelengths 91w, 92w, 93w, and 94w, which significantly affect the color tone of the emitted light, and it is possible to emit light of a desired color tone.

[0158] In the vehicle lamp 1 of the present embodiment, the multiple resonant wavelengths in the metalens 30 include a resonant wavelength 30w2 that is longer than the shortest wavelength 91w and shorter than the longest wavelength 94w among the wavelengths 91w, 92w, 93w, and 94w of the multiple peaks 91, 92, 93, and 94. In addition, the wavelength of the light from the light source unit 20 that has the smallest intensity between the adjacent peaks 92 and 93 is the same as this resonant wavelength 30w2. With this configuration, it is possible to suppress a decrease in the amount of emitted light, compared to a case in which the wavelength of the light excluding the light that has the smallest intensity between the peaks 92 and 93 is the same as this resonant wavelength 30w2.

[0159] The eighth embodiment has been used as an example to describe a vehicle lamp 1 including a light source unit 20 whose spectral distribution of emitted light has multiple peaks, and a metalens 30 whose multiple resonant wavelengths are different from the wavelengths of the multiple peaks. However, such a vehicle lamp 1 is not limited to this. A modified example of the eighth embodiment will be described below.

[0160] For example, in the eighth embodiment, the light source unit 20 that emits light L having a spectral distribution 90 with four peaks 91, 92, 93, and 94 has been described as an example. However, the light source unit 20 may be configured to emit light having a spectral distribution with multiple peaks. For example, the light source unit 20 may have a light shielding plate that blocks a part of the light emitted from the light emitting element 21, or may have a reflecting plate that reflects at least a part of the light emitted from the light emitting element 21. In addition, the number of peaks in the spectral distribution 90 of the light L emitted from the light source unit 20 is not particularly limited. For example, the light source unit 20 may be configured to emit light having a spectral distribution shown in FIG. 21. Note that FIG. 21 is a diagram similar to FIG. 20 showing the spectral distribution of light emitted from the light source unit according to the sixth modified example, and the light transmittance distribution of the metalens. Hereinafter, the sixth modified example in which the spectral distribution of the light emitted from the light source unit becomes the spectral distribution shown in FIG. 21 will be described. Note that, for components that are the same as or equivalent to those in the eighth embodiment, the same reference symbols are used and duplicated descriptions are omitted unless otherwise specified.

[0161] The spectral distribution 90 in this modification has two peaks 91 and 92. The wavelength 91w at the peak 91 is shorter than the wavelength 92w at the peak 92. In this modification, the wavelength 91w is approximately 460 nm, and the wavelength 92w is approximately 570 nm. The intensity at the peak 91 is higher than the intensity at the peak 92 and is the maximum in the entire spectral distribution 90. The diameter of the nanostructure 35 in this modification is smaller than the wavelength 92w at the peak 92. All of the multiple resonant wavelengths in the metalens 30 of this modification are different from the wavelengths 91w and 92w of the two peaks 91 and 92, respectively. For this reason, the vehicular lamp 1 of this modification can emit light of a desired color tone, as compared to a case in which at least one of the multiple resonant wavelengths is the same as the wavelengths 91w and 92w at either of the peaks 91 and 92, as in the first embodiment.

[0162] Furthermore, the second longest resonant wavelength 30w2 is longer than the shortest wavelength 91w among these wavelengths 91w, 92w and shorter than the longest wavelength 92w. That is, the multiple resonant wavelengths include a resonant wavelength 30w2 that is longer than the shortest wavelength 91w among these wavelengths 91w, 92w and shorter than the longest wavelength 92w. Therefore, according to this modification, similar to the first embodiment, it is possible to prevent the design of the size and shape of the nanostructure 35 in each cell 33, the arrangement of the cells 33, and the like from becoming complicated.

[0163] In this modification, the wavelength of the light from the light source unit 20 having the smallest intensity between the adjacent peaks 91, 92 is the same as the resonance wavelength 30w2. Therefore, according to this modification, as in the eighth embodiment, a decrease in the amount of emitted light can be suppressed compared to a case in which the wavelength of the light excluding the light having the smallest intensity between the peaks 91, 92 is the same as the resonance wavelength 30w2.

[0164] In this modification, the multiple resonant wavelengths in the metalens 30 include a resonant wavelength 30w2 included in the wavelength band of the light L from the light source unit 20. The maximum intensity in the entire spectral distribution 90 is the intensity at the peak 91, and the ratio of the intensity of the light of the resonant wavelength 30w2 in the light L from the light source unit 20 to this intensity is 0.1 or less. Therefore, according to this modification, the decrease in the amount of emitted light can be suppressed compared to when this ratio exceeds 0.1. Furthermore, by adopting such a configuration, it is possible to easily emit light of a desired color tone compared to when this ratio exceeds 0.1. Note that this ratio is more preferably zero. However, this ratio may be greater than 0.1. In addition, from the viewpoint of suppressing the decrease in the amount of emitted light, it is preferable that the ratio of the amount of light of the same wavelength as the resonant wavelength 30w2 in the light L from the light source unit 20 to the total amount of light L from the light source unit 20 is less than 4%.

[0165] Furthermore, in the eighth embodiment and the sixth modified example, a metalens 30 has been described as an example in which the second longest resonance wavelength 30w2 is included in the wavelength band of the light L from the light source unit 20. However, the longest resonance wavelength 30w1 may be included in the wavelength band of the light L from the light source unit 20, and all of the resonance wavelengths may not be included in the wavelength band of the light L from the light source unit 20.

[0166] Furthermore, in the eighth embodiment and the sixth modified example, a metalens 30 in which all of the multiple resonant wavelengths are different from the respective wavelengths of the multiple peaks has been described as an example. However, it is sufficient that the multiple resonant wavelengths are different from the respective wavelengths of the multiple peaks, and for example, a specific resonant wavelength may be the same as the wavelength of a certain peak. From the viewpoint of emitting light of a desired color tone, it is preferable that all of the multiple resonant wavelengths are different from the respective wavelengths of the multiple peaks.

[0167] Furthermore, from the perspective of emitting light of a desired color tone, it is preferable that the light transmittance distribution of the metalens 30 has a relative transmittance of 80% or less based on the maximum transmittance of the light L from the light source unit 20 that passes through the metalens 30, includes a plurality of consecutive resonant wavelength bands that include one resonant wavelength, and at least one of these resonant wavelength bands is different from the wavelengths of the respective peaks. In this case, it is more preferable that all of these resonant wavelength bands are different from the wavelengths of the respective peaks. Note that, if the light transmittance distribution of the metalens 30 has a relative transmittance of 60% or less based on the maximum transmittance of the light L from the light source unit 20 that passes through the metalens 30, and includes a plurality of consecutive resonant wavelength bands that include one resonant wavelength, it is more preferable that at least one of these resonant wavelength bands is different from the wavelengths of the respective peaks. In this case, it is more preferable that all of these resonant wavelength bands are different from the wavelengths of the respective peaks. Furthermore, if the light transmittance distribution of the metalens 30 has a relative transmittance of 40% or less based on the maximum transmittance of light L from the light source unit 20 passing through the metalens 30, and includes a plurality of continuous resonance wavelength bands including one resonance wavelength, it is more preferable that at least one of these resonance wavelength bands is different from each of the wavelengths of the plurality of peaks. In this case, it is more preferable that all of these resonance wavelength bands are different from each of the wavelengths of the plurality of peaks.

[0168] Although the present invention has been described above using the above-mentioned embodiment and modified examples as examples, the present invention is not limited to these.

[0169] For example, in the above embodiment, the vehicle lamp 1 is a headlamp, but is not particularly limited thereto. For example, the vehicle lamp 1 may be configured to irradiate an illuminated object such as a road surface with light constituting an image. Furthermore, when the vehicle lamp is configured to irradiate an illuminated object such as a road surface with light constituting an image, the direction of the light emitted by the vehicle lamp and the position at which the vehicle lamp is attached to the vehicle are not particularly limited. Furthermore, the color of the light emitted by the vehicle lamp is not limited to white.

[0170] Furthermore, in the above embodiment, the metalens 30 that reduces the divergence angle of the light L from the light source unit 20 has been described as an example. However, the metalens 30 may be configured to increase the divergence angle of the light L from the light source unit 20.

[0171] In the above embodiment, the metalens 30 is described as having planar primary surfaces 31s and 32s as the metaregion. However, the primary surfaces 31s and 32s as the metaregion may be curved. However, from the viewpoint of making the metalens 30 thinner, it is preferable that the primary surfaces 31s and 32s as the metaregion are planar.

[0172] In the above first to fourth embodiments, the specific phase distribution 60 having three or more peaks 61 has been described as an example. However, the number of peaks 61 is not particularly limited. For example, the specific phase distribution 60 may not have a peak 61.

[0173] According to the present invention, a vehicle lamp that can be made compact is provided and can be used in fields such as vehicle lamps for automobiles and the like.

Claims

1. A light source unit; a metalens having a metaregion in which a plurality of cells including nanostructures having a wavelength smaller than the longest wavelength of the light emitted from the light source unit are arranged and through which the light emitted from the light source unit transmits; Equipped with the meta region changes a phase distribution of the light passing through the meta region; an incident surface of the metalens on which the light from the light source unit is incident is curved convexly outward to refract the light so that a divergence angle of the light is reduced; The light incident on the incident surface is transmitted through the meta-region. A vehicle lamp characterized by the above.

2. The light-transmitting device further includes a protective member that covers the meta region.

2. The vehicle lamp according to claim 1.

3. The protective member has a refractive index lower than the refractive index of the metalens and fills spaces between the nanostructures.

3. The vehicle lamp according to claim 2.

4. A light source unit; a metalens having a metaregion in which a plurality of cells including nanostructures having a wavelength smaller than the longest wavelength of the light emitted from the light source unit are arranged and through which the light emitted from the light source unit transmits; Equipped with the metaregion changes a phase distribution of the light passing through the metaregion, and when a reference light parallel to a reference axis orthogonal to the metaregion is incident on the metaregion at a specific position in the metaregion, changes the phase distribution of the reference light such that the phase distribution of the reference light exiting the metalens becomes a specific phase distribution consisting of a remainder when a predetermined phase distribution is divided by 2π; the predetermined phase distribution is a phase distribution in which a phase delay (rad) decreases and a rate of decrease of the phase delay increases as the phase moves away from the reference axis, the particular phase distribution has multiple peaks; The plurality of cells are arranged such that, when viewed along the reference axis, two or more of the cells are located between adjacent peaks in a direction away from the specific position. A vehicle lamp characterized by the above.

5. the particular phase distribution has three or more of the peaks, The number of cells located between the peaks decreases with distance from the particular location.

5. The vehicle lamp according to claim 4.

6. The nanostructure has a cylindrical shape, The number of the cells located between the peaks is 3 or more.

6. A vehicle lamp according to claim 4 or 5.

7. The minimum width of the meta region is 10 mm or more.

7. A vehicle lamp according to claim 1, wherein the first and second electrodes are arranged in a first direction.

8. A light source unit; a metalens having a metaregion in which a plurality of cells including nanostructures having a wavelength smaller than the longest wavelength of the light emitted from the light source unit are arranged and through which the light emitted from the light source unit transmits; Equipped with The meta region changes a phase distribution of the light passing through the meta region so that coma aberration occurs, and the divergence angle of the light passing through the meta region is expanded in the left-right direction of a light distribution pattern formed by the light compared to a case in which the coma aberration does not occur. A vehicle lamp characterized by the above.

9. The meta area makes the amount of spread of the divergence angle in the left direction due to the coma aberration equal to the amount of spread of the divergence angle in the right direction due to the coma aberration.

9. A vehicle lamp according to claim 8.

10. The meta region makes one of the amount of spread of the divergence angle in the left direction due to the coma aberration and the amount of spread of the divergence angle in the right direction due to the coma aberration larger than the other.

9. A vehicle lamp according to claim 8.

11. The meta region widens the divergence angle of the light passing through the meta region in the vertical direction of a light distribution pattern formed by the light, compared to when the coma aberration does not occur.

11. The vehicular lamp according to claim 8,

12. The meta region makes the amount of spread of the divergence angle in the left-right direction due to the coma aberration larger than the amount of spread of the divergence angle in the up-down direction due to the coma aberration.

12. A vehicle lamp according to claim 11.

13. A light source unit; a metalens having a metaregion in which a plurality of cells including nanostructures having a wavelength smaller than the longest wavelength of the light emitted from the light source unit are arranged and through which the light emitted from the light source unit transmits; Equipped with The meta region changes a phase distribution of the light passing through the meta region, and the bending force of the meta region bending infrared light contained in the light passing through the meta region is made smaller than the bending force of the meta region bending visible light contained in the light passing through the meta region. A vehicle lamp characterized by the above.

14. The meta-region is configured such that, in the visible light and the infrared light having a wavelength ratio of 1:1.5, the amount of phase modulation of the infrared light is less than 0.6 times the amount of phase modulation of the visible light.

14. A vehicle lamp according to claim 13.

15. The longest wavelength of the visible light is 660 nm, The shortest wavelength of the infrared light is 1000 nm.

15. A vehicular lamp according to claim 13 or 14.

16. The nanostructure has a cylindrical shape.

16. A vehicular lamp according to claim 13, wherein the light source is a light source for a vehicle.

17. A light source unit; a metalens having a metaregion in which a plurality of cells including nanostructures having a wavelength smaller than the longest wavelength of the light emitted from the light source unit are arranged and through which the light emitted from the light source unit transmits; Equipped with the meta region changes a phase distribution of the light passing through the meta region; At least one resonant wavelength in the metalens is greater than or equal to 800 nm and less than 2400 nm. A vehicle lamp characterized by the above.

18. The at least one resonant wavelength is in the range of 800 nm to less than 900 nm.

18. A vehicular lamp according to claim 17.

19. the spectral distribution of the light emitted from the light source unit has a plurality of peaks, The plurality of resonant wavelengths are different from the respective wavelengths of the plurality of peaks.

19. A vehicular lamp according to claim 17 or 18.

20. All of the plurality of resonance wavelengths are not included in the wavelength band of the light emitted from the light source unit.

20. A vehicle lamp according to claim 19.

21. The metalens reduces a divergence angle of the light from the light source unit that transmits through the metalens.

21. The vehicular lamp according to claim 17,

22. A light source unit; a metalens having a metaregion in which a plurality of cells including nanostructures having a wavelength smaller than the longest wavelength of the light emitted from the light source unit are arranged and through which the light emitted from the light source unit transmits; Equipped with the meta region changes a phase distribution of the light passing through the meta region; the spectral distribution of the light emitted from the light source unit has a plurality of peaks, The resonant wavelengths of the metalens are different from the wavelengths of each of the peaks. A vehicle lamp characterized by the above.

23. At least one of the plurality of resonant wavelengths is greater than the shortest wavelength and less than the longest wavelength of each of the plurality of peaks.

23. A vehicular lamp according to claim 22.

24. The wavelength of the light having the smallest intensity between the adjacent peaks is the same as the at least one of the plurality of resonant wavelengths.

24. A vehicular lamp according to claim 23.

25. the plurality of resonant wavelengths include a specific resonant wavelength included in the wavelength band of the light from the light source unit, The ratio of the intensity of the light having the specific resonance wavelength in the light to the maximum intensity in the entire spectral distribution of the light is 0.1 or less.

25. A vehicular lamp according to any one of claims 22 to 24.

Images