Retina projection device

Abstract

To reduce chromatic aberration. [Solution] The retinal projection device is a device mounted on a near-eyewear wearable device and comprises a light source that emits laser light, a movable mirror that performs scanning with the laser light Ls, and a reflector 14 that reflects the laser light Ls that has passed through the movable mirror and projects an image onto the retina by irradiating the retina of the user wearing the near-eyewear wearable device with reflected light Lref. The reflector 14 has a reflection angle θ that changes depending on the wavelength of the laser light Ls. r It includes a reflective layer 15 that reflects the laser light Ls and emits it as reflected light Lref, and a phase correction layer 17 that corrects the chromatic aberration of the reflected light Lref.

Description

Technical Field

[0001] The present disclosure relates to a retinal projection device.

Background Art

[0002] Near-eye wearable devices such as smart glasses are known. For example, Patent Document 1 discloses a near-eye display assembly including an image source and a combiner including a nanostructured surface optically coupled to the image source, wherein image information is formed on the nanostructured surface of the combiner to convey the image information within the user's field of view.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the near-eye display assembly described in Patent Document 1, the nanostructured surface functions as a reflective surface. In reflectors such as mirrors (metaoptical mirrors) and diffractive mirrors composed of such nanostructures, the reflection angle of light may change depending on the wavelength of light. Therefore, when an image is projected onto the user's retina, chromatic aberration may occur.

[0005] The present disclosure describes a retinal projection device capable of reducing chromatic aberration.

Means for Solving the Problems

[0006] One aspect of this disclosure relates to a retinal projection device that is mounted on a near-eyewear device. The retinal projection device comprises a light source that emits laser light, a movable mirror that performs scanning with the laser light, and a reflector that reflects the laser light that has passed through the movable mirror and projects an image onto the retina by irradiating the reflected light onto the retina of a user wearing the near-eyewear device. The reflector includes a reflective layer that reflects the laser light at a reflection angle that changes depending on the wavelength of the laser light and emits it as reflected light, and a phase correction layer that corrects the chromatic aberration of the reflected light.

[0007] In this retinal projection device, the laser light is reflected as reflected light in the reflective layer at a reflection angle that changes depending on the wavelength of the laser light, and the chromatic aberration of the reflected light is corrected by the phase correction layer. Therefore, it is possible to reduce chromatic aberration.

[0008] In some embodiments, the phase correction layer may be a metalens comprising a plurality of columnar bodies that transmit visible light. In this case, when visible light passes through the columnar bodies, a phase delay of the visible light occurs according to the size of the columnar bodies. Therefore, chromatic aberration can be reduced by appropriately adjusting the amount of phase delay that occurs in each columnar body.

[0009] In some embodiments, the phase correction layer may be composed of a compound selected from a set consisting of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride. Since these compounds are transparent in the visible light region, visible light transmittance of the phase correction layer can be achieved.

[0010] In some embodiments, the sizes of the columnar bodies may be set such that the phases of red light and blue light are in phase at the positions where the columnar bodies are provided. The maximum wavelength in the wavelength band used by the retinal projection device is the wavelength of red light, and the minimum wavelength in the wavelength band used is the wavelength of blue light. Therefore, by making the phases of red light and blue light in phase, the maximum phase delay occurring in the wavelength band used can be eliminated. Thus, chromatic aberration can be reduced.

[0011] In some embodiments, the reflective layer may be a metamirror comprising a plurality of nanostructures provided along the surface of the lens of the near eyewear device facing the user's eyeball. Each of the plurality of nanostructures may include a metal layer, a dielectric layer, and a metallic body, stacked sequentially in a direction intersecting the surface. In this case, the reflective layer can function as a reflective mirror due to electromagnetic resonance between the metal layer and the metallic body.

[0012] In some embodiments, the reflective layer may be a metamirror comprising a plurality of nanostructures provided along the surface of the lens of the near eyewear device facing the user's eyeball. Each of the plurality of nanostructures may include a first transparent conductive layer, a dielectric layer, and a second transparent conductive layer, stacked sequentially in a direction intersecting the surface. In this case, the reflective layer can function as a reflective mirror due to electromagnetic resonance between the first transparent conductive layer and the second transparent conductive layer. Furthermore, the use of transparent conductive layers makes it possible to reduce the possibility of obstruction of the field of view.

[0013] In some embodiments, the first transparent conductive layer and the second transparent conductive layer may be made of ITO. ITO is suitable for transparent conductive layers because it has excellent conductivity and high transparency in the visible light region.

[0014] In some embodiments, the reflective layer may be configured to obtain a predetermined reflection angle with respect to a reference wavelength. Since the reflection angle in the reflective layer changes depending on the wavelength, the length along the surface of the metal body can be set by using the reference wavelength.

[0015] In some embodiments, the reference wavelength may be the wavelength of red light contained in the laser beam. In this case, the length along the surface of the metal body can be increased, which facilitates the manufacture of the reflector.

[0016] In some embodiments, the reflector may further include a dielectric spacer layer provided between the reflective layer and the phase correction layer. In this case, the provision of the dielectric spacer layer allows the surface of the dielectric spacer layer to be planarized by surface planarization treatment such as CMP.

[0017] In some embodiments, the dielectric spacer layer may be composed of a compound selected from a set consisting of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride. In this case, a material having the same or a similar refractive index as the phase correction layer may be used, thereby suppressing unwanted interfacial reflections. [Effects of the Invention]

[0018] According to each aspect and embodiment of this disclosure, chromatic aberration can be reduced. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a perspective view showing the external appearance of a near-eyewear device including a retinal projection device according to one embodiment. [Figure 2] Figure 2 is a schematic diagram showing the retinal projection device shown in Figure 1. [Figure 3] Figure 3 is a magnified view of the reflector shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view along the line IV-IV in Figure 3. [Figure 5] Figure 5 is a perspective view showing the reflective layer included in the unit region shown in Figure 3. [Figure 6] Figure 6 is a schematic diagram showing the reflector shown in Figure 2. [Figure 7] Figure 7(a) is a diagram illustrating the reflected light at position (-r). Figure 7(b) is a diagram illustrating the reflected light at position (+r). [Figure 8] Figure 8 shows the relationship between the position of the reflector in the X-axis direction and the maximum phase delay. [Figure 9]Figure 9 shows the relationship between the diameter of the columnar body and the amount of phase delay. [Figure 10] Figure 10 shows the diameter of the columnar body at various positions along the X-axis of the reflector. [Figure 11] Figure 11 is a diagram illustrating the formation of the reflective layer. [Figure 12] Figure 12 is a diagram illustrating the formation of the dielectric layer. [Figure 13] Figure 13 is a diagram illustrating the planarization of the dielectric layer. [Figure 14] Figure 14 is a diagram illustrating the formation of the translucent layer. [Modes for carrying out the invention]

[0020] Embodiments of the present disclosure will be described in detail below with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. Each figure may show an XYZ coordinate system. The Y-axis direction is the direction that intersects (for example, is perpendicular to) the X-axis and Z-axis directions. The Z-axis direction is the direction that intersects (for example, is perpendicular to) the X-axis and Y-axis directions.

[0021] A near-eyewear device including a retinal projection device according to one embodiment will be described with reference to Figure 1. Figure 1 is a perspective view showing the external appearance of a near-eyewear device including a retinal projection device according to one embodiment. The near-eyewear device 1 shown in Figure 1 is a device that superimposes an image onto the field of view of the real world. The near-eyewear device 1 is, for example, a head-mounted device and can take the form of glasses, goggles, a hat, or a helmet. Examples of near-eyewear devices 1 include smart glasses such as AR (Augmented Reality) glasses and MR (Mixed Reality) glasses. The near-eyewear device 1 includes a frame 2, a lens 3, and a retinal projection device 10.

[0022] The frame 2 includes a pair of rims 2a, a bridge 2b, and a pair of temples 2c. The rims 2a are the parts that hold the lenses 3. The bridge 2b is the part that connects the pair of rims 2a. The temples 2c extend from the rims 2a and are the parts that rest on the user's ears. The frame 2 may be a rimless frame. The lenses 3 have an inner surface 3a (see Figure 2) that faces the eyeball E (see Figure 2) of the user wearing the near eyewear device 1.

[0023] In this embodiment, the retinal projection device 10 directly projects (draws) an image onto the retina RE (see Figure 2) of the user wearing the near-eyewear device 1. The retinal projection device 10 is mounted on the near-eyewear device 1. In this embodiment, the near-eyewear device 1 includes two retinal projection devices 10 in order to project images onto both the left and right retina RE, but it may also include only one of the retinal projection devices 10.

[0024] Next, the retinal projection device 10 will be described in detail with reference to Figure 2. Figure 2 is a schematic diagram showing the retinal projection device shown in Figure 1. As shown in Figure 2, the retinal projection device 10 includes a light source unit 11 (light source), a collimator lens 12, a movable mirror 13, and a reflector 14.

[0025] The light source unit 11 emits laser light. For example, a full-color laser module is used as the light source unit 11. The light source unit 11 includes a red laser diode, a green laser diode, a blue laser diode, and a multiplexer that combines the laser light emitted from each laser diode. The light source unit 11 emits the combined laser light. The combined laser light has a red wavelength λ red Light having (red light Lr), green wavelength λ green Light having (green light Lg), and blue wavelength λ blueIt contains at least one component of light having (blue light Lb). In the following description, red light Lr, green light Lg, and blue light Lb may be referred to as "visible light," and red light Lr, green light Lg, and blue light Lb may be collectively referred to as "laser light Ls." The light source unit 11 emits laser light of a color and intensity corresponding to the pixels of the image projected onto the retina RE.

[0026] The collimator lens 12 is an optical component that converts the laser light emitted from the light source unit 11 into parallel light. The collimator lens 12 is located between the light source unit 11 and the movable mirror 13.

[0027] The movable mirror 13 is an optical component for scanning with laser light Ls. The movable mirror 13 is positioned in the direction of emission of the laser light, which has been converted into parallel light by the collimator lens 12. The movable mirror 13 is configured to swing, for example, around an axis extending in the lateral direction (X-axis direction) of the lens 3 and around an axis extending in the vertical direction (Y-axis direction) of the lens 3, and reflects the laser light by changing the angle in the X-axis and Y-axis directions. For example, a MEMS (Micro Electro Mechanical Systems) mirror can be used as the movable mirror 13.

[0028] The reflector 14 is an optical component that reflects the laser light Ls, which has passed through the movable mirror 13, and projects an image onto the retina RE of the user wearing the near-eyewear device 1 by irradiating the reflected light Lref onto the retina RE. No image is displayed on the reflector 14. The reflector 14 is provided on the inner surface 3a of the lens 3. Details of the reflector 14 will be described later.

[0029] Although not shown in the diagram, the retinal projection device 10 further includes a laser driver for driving the light source unit 11, a mirror driver for driving the movable mirror 13, and a controller for controlling the laser driver and the mirror driver.

[0030] Next, the configuration of the reflector 14 will be described while referring to FIGS. 3 to 5. FIG. 3 is a diagram showing an enlarged view of the reflector shown in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3. FIG. 5 is a perspective view showing the reflection layer included in the unit area shown in FIG. 3.

[0031] As shown in FIG. 3, the reflector 14 is divided into a plurality of unit areas 40. The plurality of unit areas 40 are provided along the inner surface 3a of the lens 3. The plurality of unit areas 40 are arranged in a two-dimensional array in the lateral direction (X-axis direction) and the longitudinal direction (Y-axis direction) of the lens 3.

[0032] As shown in FIG. 4, each unit area 40 is configured to reflect the laser beam Ls at a reflection angle θ corresponding to the position where the unit area 40 is provided when the laser beam Ls is incident on the unit area 40. The reflection angle θ of each unit area 40 is set so that the laser beam Ls (reflected light Lref) reflected by each unit area 40 passes through the center of the pupil PP (see FIG. 2). Therefore, the incident angle θ r and the reflection angle θ r are determined by the position where the unit area 40 is provided. The unit area 40 is configured so that the incident angle θ i and the reflection angle θ r corresponding to the position where the unit area 40 is provided can be obtained.

[0033] Here, the incident angle θ i is the angle formed by the normal line of the surface irradiated with the laser beam Ls and the incident direction of the laser beam Ls. The reflection angle θ r is the angle formed by the normal line of the surface irradiated with the laser beam Ls and the emission direction of the reflected light Lref. In the plane including the laser beam Ls and the reflected light Lref, when the reflected light Lref is emitted to the opposite side of the incident light (laser beam Ls) with the normal line as the boundary, the reflection angle θ r is represented by a positive value, and when the reflected light Lref is emitted to the same side as the incident light (laser beam Ls) with the normal line as the boundary, the reflection angle θ r is represented by a negative value.

[0034] ​​​​ As shown in Figures 4 and 5, the reflector 14 includes a reflective layer 15, a dielectric spacer layer 16, and a phase correction layer 17, which are stacked in order in a direction (Z-axis direction) that intersects (for example, is perpendicular to) the inner surface 3a.

[0035] The reflective layer 15 is a metamirror containing multiple nanostructures arranged along the inner surface 3a. A metamirror is also called a metaoptics mirror. The reflective layer 15 has a reflection angle θ that changes depending on the wavelength of the laser light Ls. r The laser beam Ls is reflected by the reflective layer 15 and emitted as reflected light Lref. The reflective layer 15 has a reflection angle θ corresponding to the position where the laser beam Ls was incident. r The reflective layer 15 is configured to reflect the laser beam Ls. The reflective layer 15 includes a metal layer 51, a dielectric layer 52, a metal layer 53, and a protective layer 54, which are stacked in order in a direction (Z-axis direction) that intersects (for example, is perpendicular to) the inner surface 3a.

[0036] The metal layer 51 is the base layer. The metal layer 51 is provided on the inner surface 3a of the lens 3. The metal layer 51 is made of a metal that has high reflectivity in the visible light region. For example, the metal layer 51 is made of a metal containing at least one element selected from the set consisting of gold (Au), copper (Cu), silver (Ag), and aluminum (Al). The length of the metal layer 51 in the Z-axis direction is sufficient to allow the metal layer 51 to conduct a resonant current and to reflect light, for example, 10 nm to 1000 nm. Hereinafter, the length in the Z-axis direction may be referred to as "thickness".

[0037] The dielectric layer 52 is a layer that functions as a spacer. The dielectric layer 52 is provided between the metal layer 51 and the metal layer 53 in the Z-axis direction. The dielectric layer 52 has a main surface 52a on which the metal layer 53 is provided. The dielectric layer 52 has a dielectric constant such that it does not hinder the electromagnetic interaction between the metal layer 51 and the metal layer 53. The dielectric layer 52 is made of a material that is transparent in the visible light region. The dielectric layer 52 may be made of a material with a high dielectric constant in order to achieve high reflectivity. The dielectric layer 52 is made of a compound selected from a set consisting of, for example, silicon oxide (e.g., SiO2), titanium oxide (e.g., TiO2), magnesium oxide (e.g., MgO), and aluminum oxide (e.g., Al2O3). The thickness of the dielectric layer 52 is, for example, 10 nm to 100 nm.

[0038] The metal layer 53 is a layer that excites electromagnetic resonance together with the metal layer 51. The metal layer 51 and the metal layer 53 are stacked in the Z-axis direction via the dielectric layer 52. In this embodiment, the metal layer 53 is provided on the main surface 52a of the dielectric layer 52. The metal layer 53 is composed of a metal having high reflectivity in the visible light region. For example, the metal layer 53 is composed of a metal containing at least one element selected from a set consisting of silver (Ag), aluminum (Al), and copper (Cu).

[0039] The metal layer 53 includes a plurality of metal bodies 55. Each of the metal bodies 55 is provided in each of the plurality of unit regions 40. Each metal body 55 is configured such that the phase change amount φ of the reflected light Lref by the metal body 55 changes linearly from one end 40a to the other end 40b in the X-axis direction of the unit region 40 in which the metal body 55 is provided. Furthermore, each metal body 55 is configured such that the phase change amount φ of the reflected light Lref changes substantially by 360° (2π radians) from one end 40a to the other end 40b. The phase change amount φ of the reflected light Lref is the amount of phase change of the reflected light Lref when the length of the metal body 55 in the Y-axis direction is changed, with the phase of the reflected light Lref at a certain length in the Y-axis direction of the metal body 55 as a reference. Hereinafter, the length in the Y-axis direction may be referred to as "width".

[0040] In this embodiment, each metal body 55 is a single metal body having a trapezoidal shape when viewed from the Z-axis direction. The thickness of each metal body 55 is, for example, 10 nm to 100 nm. The length of each metal body 55 in the X-axis direction is the same as or slightly shorter than the length Lx of the unit region 40 in the X-axis direction. The length of each metal body 55 in the X-axis direction is, for example, 500 nm to 2500 nm.

[0041] The length of the short side (width W1) of each metal body 55 is set, for example, to near the resolution of the exposure apparatus used to form the metal body 55. The width W1 is, for example, 10 nm to 200 nm. The length of the long side (width W2) of each metal body 55 is greater than the width W1 and is set to a length that yields a phase difference of substantially 360° (2π radians) from the phase of the reflected light Lref at width W1. The width W2 is, for example, 100 nm to 500 nm. Each metal body 55 is formed, for example, by photolithography.

[0042] The protective layer 54 is a layer that protects the metal layer 53 (metal body 55). The protective layer 54 is provided on the surface 55a of each metal body 55 and covers the surface 55a. The surface 55a is the side of the metal layer 53 opposite to the dielectric layer 52. The protective layer 54 is made of a metal that is less susceptible to oxidation and sulfidation than the metal layer 53 and has higher corrosion resistance. In other words, the protective layer 54 is made of a metal that has a higher standard electrode potential than the metal that makes up the metal layer 53. The protective layer 54 is made of a metal that contains at least one element selected from the set consisting of gold (Au), ruthenium (Ru), and iridium (Ir). In combination with these metals and the metal that makes up the metal layer 53 (e.g., silver), the attenuation of near-field light is small.

[0043] In this embodiment, the protective layer 54 includes a plurality of metal bodies that have the same shape as the metal body 55 when viewed from the Z-axis direction. The thickness of the protective layer 54 (metal bodies) is 20% or less of the sum of the thickness of the metal body 55 and the thickness of the protective layer 54, for example, 2.5 nm to 25 nm.

[0044] The dielectric spacer layer 16 is a layer that absorbs the refractive index difference between the reflective layer 15 and the phase correction layer 17 while ensuring flatness before the formation of the phase correction layer 17. The dielectric spacer layer 16 is provided between the reflective layer 15 and the phase correction layer 17. The dielectric spacer layer 16 is made of a material that is transparent in the visible light region. The dielectric spacer layer 16 is made of one compound selected from a set consisting of silicon oxide (SiO2), titanium oxide (TiO), tantalum oxide (Ta2O5), and silicon nitride (SiN). The thickness of the dielectric spacer layer 16 is, for example, 50 nm or less. From the viewpoint of reducing the influence on the reflection efficiency of the reflector 14, the thickness of the dielectric spacer layer 16 may be 10 nm or less.

[0045] The phase correction layer 17 is a layer for correcting the chromatic aberration of reflected light Lref. The phase correction layer 17 is provided on the dielectric spacer layer 16. The phase correction layer 17 is made of a material that is transparent in the visible light region.

[0046] The phase correction layer 17 is a metalens containing a plurality of columnar bodies 17a. Each columnar body 17a is a columnar member that transmits visible light. In other words, each columnar body 17a is a columnar member that is transparent in the visible light region. The constituent material of the columnar bodies 17a is a material that transmits visible light and has a refractive index greater than 1. Examples of such constituent materials include silicon oxide (SiO2), titanium oxide (TiO), tantalum oxide (Ta2O5), and silicon nitride (SiN). In other words, the phase correction layer 17 is composed of one compound selected from the set consisting of silicon oxide (SiO2), titanium oxide (TiO), tantalum oxide (Ta2O5), and silicon nitride (SiN).

[0047] In this embodiment, each columnar body 17a has a cylindrical shape. The shape of each columnar body 17a is not limited to a cylinder, but may be a rectangular prism, or a frustoconical or pyramidal shape tapering to a point. Each columnar body 17a is provided standing on the dielectric spacer layer 16. That is, each columnar body 17a extends from the dielectric spacer layer 16 in the direction of emission of reflected light Lref. The height (length in the Z-axis direction) of each columnar body 17a is, for example, 500 nm or more and 2000 nm or less.

[0048] The size of each columnar body 17a is set such that the phase of the red light Lr and the phase of the blue light Lb are in phase at the location where the columnar body 17a is installed. The method for determining the size of the columnar body 17a will be described later.

[0049] As shown in Figure 4, an adhesion layer 56 may be provided between the inner surface 3a of the lens 3 and the metal layer 51. An adhesion layer 57 may be provided between the metal layer 51 and the dielectric layer 52. An adhesion layer 58 may be provided between the dielectric layer 52 and the metal layer 53. Each of the adhesion layers 56 to 58 is a layer that enhances the adhesion between the two layers. Each of the adhesion layers 56 to 58 is made of, for example, chromium (Cr). The length (film thickness) of each of the adhesion layers 56 to 58 in the Z-axis direction is about 3 nm. In Figure 5, the illustration of the adhesion layers 56 to 58 is omitted.

[0050] Next, the reflection principle in the reflective layer 15 will be explained with reference to Figures 4 and 5.

[0051] As described above, the width of the metal body 55 increases from width W1 to width W2 as it moves from one end 40a to the other end 40b. The amount of phase change φ at each position in the X-axis direction of the metal body 55 is substantially the same as the amount of phase change φ of a square metal body having sides of the same length as the width at that position in a plan view. The larger the area of ​​the square metal body in a plan view, the larger the amount of phase change φ (phase delay) at that position. Therefore, the laser light Ls is reflected with different amounts of phase change φ depending on the position in the X-axis direction, and a wavefront is formed by interference between the reflected light. That is, a plane wave is generated in which the slope of the function φ(x) that shows the relationship between the position x in the X-axis direction and the amount of phase change φ is the wave vector Φ.

[0052] Here, as shown in Figure 4, Snell's Law, when generalized, is given by the wave vector k0 of the laser light Ls and the incident angle θ. i , reflection angle θ r It can be expressed using equation (1) with respect to the wave vector Φ.

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[0053] The wave vector k0 is expressed as 2π / λ, where λ is the wavelength of the laser light Ls. Wavelength λ represents any wavelength included in the usable wavelength band. The usable wavelength band is the range (bandwidth) of wavelengths used in the retinal projection device 10. The wave vector Φ is expressed as 2π / Lx, where Lx is the length of the unit region 40 in the X-axis direction. By rearranging equation (1) using these relationships, equation (2) is obtained.

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[0054] Equation (2) contains the wavelength λ of the laser light Ls and the incident angle θ of the laser light Ls corresponding to the position where the unit region 40 is provided. i and the angle of reflection θ r By substituting and , the length Lx of the unit region 40 can be determined. Here, the reference wavelength λ refThe length Lx is determined using the wavelength λ. In other words, the reflective layer 15 is the reference wavelength λ ref A predetermined reflection angle θ r The system is configured to obtain the following. Here, the reference wavelength λ ref For example, the wavelength λ of the red component (red light Lr) contained in laser light Ls. red The reference wavelength λ is used. ref The wavelength λ of the blue component (blue light Lb) contained in laser light Ls blue This may also be used.

[0055] If length Lx is a positive value, the shape of the metal body 55 is set to a trapezoidal shape in which the width of the metal body 55 increases from one end 40a to the other end 40b. If length Lx is a negative value, the shape of the metal body 55 is set to a trapezoidal shape in which the width of the metal body 55 decreases from one end 40a to the other end 40b.

[0056] As described above, the length Lx of each unit region 40 is equal to the reference wavelength λ ref And the incident angle θ corresponding to the position where the unit region 40 is provided. i and the angle of reflection θ r This is determined from the following: The length of the metal body 55 in the X-axis direction is the same as or slightly shorter than the length Lx of the unit region 40 in the X-axis direction. Therefore, the length of the metal body 55 in the X-axis direction is the reference wavelength λ ref The incident angle θ corresponds to the position of the unit region 40 in which the metal body 55 is provided. i and the angle of reflection θ r And it is determined from. As shown in equation (2), the reflection angle θ r This changes depending on the wavelength of the optical component contained in the laser light Ls.

[0057] The length Ly in the Y-axis direction of each unit region 40 is a predetermined fixed value. The length Ly is slightly larger than the width W2. The length Ly may also be the length obtained by adding the resolution of the exposure apparatus used to form the metal body 55 (e.g., 100 nm) to the width W2, and is set to, for example, 600 nm. The widths W1 and W2 of each metal body 55 are predetermined fixed values. As described above, the width W1 is set to near the resolution of the exposure apparatus used to form the metal body 55 (e.g., 100 nm). The width W2 is set to a length (e.g., 350 nm) that yields a phase difference of substantially 360° (2π radians) from the phase of the reflected light Lref in width W1.

[0058] Next, the method for determining the size of the columnar body 17a will be explained with reference to Figures 6 to 10. Figure 6 is a schematic diagram of the reflector shown in Figure 2. Figure 7(a) is a diagram to explain the reflected light at position (-r). Figure 7(b) is a diagram to explain the reflected light at position (+r). Figure 8 is a diagram showing the relationship between the position of the reflector in the X-axis direction and the maximum phase delay. Figure 9 is a diagram showing the relationship between the diameter of the columnar body and the phase delay. Figure 10 is a diagram showing the diameter of the columnar body at each position in the X-axis direction of the reflector.

[0059] As shown in Figure 6, the position x of the center of the reflector 14 in the X-axis direction is set to 0, and of the two ends of the reflector 14 in the X-axis direction, the position x of the end closer to the movable mirror 13 is set to +r, and the position x of the end further away from the movable mirror 13 is set to -r.

[0060] Here, the phase quantity φ of the reflected light Lref at position x after wavefront adjustment. m (x) is approximated by equation (3) using wavelength λ and optical path length difference l(x). The optical path length difference l(x) is the difference in optical path length between two adjacent metal bodies 55 in the X-axis direction. In other words, equation (3) means that the phases of the laser light reflected by the two metal bodies 55 are aligned by shifting back a phase amount corresponding to the difference in optical path length between the two adjacent metal bodies 55.

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[0061] Maximum wavelength λ in the usable wavelength band max By transforming equation (3) using , we obtain equation (4).

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[0062] Here, the wavelength λ is expressed by equation (5) using the angular frequency ω and the speed of light c.

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[0063] By transforming equation (4) using equation (5), we obtain equation (6).

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[0064] The optical path length difference l(x) is given by equation (7), and the angular frequency ω is given by equation (8) using the wave number k and the speed of light c.

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[0065] By transforming equation (6) using equations (7) and (8), we obtain equation (9).

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[0066] maximum wave number k max and minimum wavenumber k min By transforming equation (9) using , we obtain equation (10).

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[0067] The first term on the right-hand side of equation (10) is the angle of reflection θ. r Since this is the optical path length difference determined by the geometric design of the reflective layer 15, it is determined by the geometric design of the reflective layer 15. Therefore, the first term on the right-hand side is a fixed value at a certain position x. The second term on the right-hand side of equation (10) changes according to the wavenumber (wavelength), and therefore corresponds to the phase correction amount by the phase correction layer 17. max Based on this case, the size of the columnar body 17a is determined to be a size corresponding to the phase correction amount. The following will explain using a specific example. Maximum wavelength λ of the usable wavelength band. max The wavelength λ of red light Lr is red The minimum wavelength λ of the wavelength band used min The wavelength λ of blue light Lb blue That is the case.

[0068] In the example shown in Figure 7(a), as shown in equation (11), at position (-r), the reflection angle θ of red light is r_red From the angle of reflection of blue light θ r_blue The angle difference obtained by subtracting is -23°. Note that the maximum wavelength λ max (wavelength λ red ) is used as the minimum wavelength λ min (wavelength λ blue 450 nm is used for the length Lx at position (-r).

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[0069] At position (-r), the incident angle θ of the laser beam Ls is... i The angle of reflection is 60°, θ r_red The reflective layer 15 is designed so that the reflection angle θ is -15°. In this case, the reflection angle θ can be seen from equation (11). r_blue The angle is +8°. The path length difference l(-r) of red light is 116 nm (= Lx × cos(90° - |θ). r_red |)) and the optical path length difference l(-r) for blue light is 70 nm (= Lx × cos(90° - |θ)r_blue Therefore, the phase change amount φ(k) corresponds to the optical path length difference l(-r) of red light. min ,-r) is 1.16 radians (= 2π × optical path length difference l(-r) / λ max ) is the phase change amount φ(k) which corresponds to the optical path length difference l(-r) of blue light. max ,-r) is 0.87 radians (= 2π × optical path length difference l(-r) / λ min Therefore, the maximum phase difference (maximum phase delay) in the usable wavelength band at position (-r) is 0.29 radians.

[0070] In the example shown in Figure 7(b), as shown in equation (12), at position (+r), the reflection angle θ of red light is r_red From the angle of reflection of blue light θ r_blue The angle difference obtained by subtracting is -9°. The length Lx at position (+r) is set to 1150 nm.

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[0071] At position (+r), the incident angle θ of the laser beam Ls is... i The angle is 45°, and the reflection angle θ r_red The reflective layer 15 is designed so that the angle is +15°. In this case, the reflection angle θ can be seen from equation (12). r_blue The value is +24°. The optical path length difference l(+r) for red light is 298 nm, and the optical path length difference l(+r) for blue light is 468 nm. Therefore, the phase change amount φ(k) corresponds to the optical path length difference l(+r) for red light. min ,+r) is 2.97 radians and corresponds to the phase change amount φ(k) of the optical path length difference l(+r) of blue light. max The value at position (+r) is 6.53 radians. The maximum phase difference (maximum phase delay) in the usable wavelength band at position (+r) is -3.56 radians.

[0072] Assuming that the maximum phase difference (maximum phase delay) in the operating wavelength band from position (+r) to position (-r) can be expressed as a linear function of position x, the relationship between position x and the maximum phase delay is obtained as shown in Figure 8. The horizontal axis of Figure 8 represents position x (in mm), and the vertical axis of Figure 8 represents the maximum phase delay (in radians). In this example, position (+r) is 3.8 mm and position (-r) is -3.8 mm.

[0073] At each position x, the size of the columnar body 17a is determined so that the maximum phase delay amount shown in Figure 8 is obtained. In this embodiment, in order to facilitate the manufacture of the reflector 14, all columnar bodies 17a included in the phase correction layer 17 are cylindrical in shape, made of the same material, and set to the same height. In this case, the diameter of the columnar body 17a becomes a parameter that determines the phase delay amount.

[0074] As shown in Figure 9, the phase delay amount due to the columnar body 17a changes depending on the diameter of the columnar body 17a, provided that the constituent material and height of the columnar body 17a are the same. The horizontal axis of Figure 9 shows the diameter of the columnar body 17a (unit: μm), and the vertical axis of Figure 9 shows the phase delay amount (unit: radians). The characteristics shown in Figure 9 are characteristics that were calculated in advance by numerical calculation. Characteristic C1 is the characteristic of a cylindrical columnar body made of tantalum pentoxide (Ta2O5) with a height of 500 nm, and aluminum oxide (Al2O3) with a height of 200 Å provided at both ends. Characteristic C2 is the characteristic of a cylindrical columnar body made of silicon nitride (SiN) with a height of 500 nm. Characteristic C3 is the characteristic of a cylindrical columnar body made of silicon dioxide (SiO2) with a height of 2 μm.

[0075] The diameter of each columnar body 17a is determined from the characteristics shown in Figure 9 so that the maximum phase delay shown in Figure 8 is obtained. This determines the diameter of the columnar body 17a at each position x, as shown in Figure 10. The horizontal axis of Figure 10 shows the position x (unit: mm), and the vertical axis of Figure 10 shows the diameter of the columnar body 17a (unit: nm). Figure 10 shows the diameter of the columnar body 17a at each position x for each constituent material shown in Figure 9. Graph PS1 shows the diameter of the columnar body 17a at each position x when the constituent material shown by characteristic C1 is used. Graph PS2 shows the diameter of the columnar body 17a at each position x when the constituent material shown by characteristic C2 is used. Graph PS3 shows the diameter of the columnar body 17a at each position x when the constituent material shown by characteristic C3 is used.

[0076] The maximum phase delay shown in Figure 8 is 0 radians when position x is -3.2 mm. Therefore, when position x is -3.2 mm or less, the diameter of the columnar body 17a at each position x is determined based on the diameter at 2π radians, as shown in Figure 9. If there is no diameter that yields the maximum phase delay at a certain position, the columnar body 17a does not need to be provided at that position. Alternatively, a columnar body 17a with a diameter that yields the phase delay closest to the maximum phase delay may be provided.

[0077] Next, the manufacturing method of the reflector 14 will be explained with reference to Figures 11 to 14. Figure 11 is a diagram illustrating the formation of the reflective layer. Figure 12 is a diagram illustrating the formation of the dielectric layer. Figure 13 is a diagram illustrating the planarization of the dielectric layer. Figure 14 is a diagram illustrating the formation of the translucent layer.

[0078] First, a substrate 50 is prepared and set in a vacuum deposition apparatus. Then, a metal layer 51 is formed in a desired area on the surface 50a of the substrate 50. Specifically, the metal layer 51 is formed by vacuum deposition using a method such as DC (Direct Current) sputtering. For the formation of the metal layer 51, a metal material is used that is composed of any metal selected from the set of gold (Au), copper (Cu), silver (Ag), and aluminum (Al), or a metal alloy containing at least one element selected from the above set.

[0079] Furthermore, in order to improve the adhesion between the surface 50a of the substrate 50 and the metal layer 51, an adhesion layer 56 may be formed on the surface 50a, and the metal layer 51 may be formed on the adhesion layer 56. The adhesion layer 56 is formed using, for example, a method such as sputtering or vapor deposition. For example, chromium (Cr) can be used to form the adhesion layer 56. The length (film thickness) of the adhesion layer 56 in the Z-axis direction is, for example, 3 nm.

[0080] Next, a dielectric layer 52 is formed on the metal layer 51. Specifically, the dielectric layer 52 is formed by vacuum deposition using a method such as RF (Radio Frequency) sputtering. For the formation of the dielectric layer 52, dielectric materials such as silicon dioxide (SiO2), titanium dioxide (TiO2), magnesium oxide (MgO), or aluminum oxide (Al2O3), which can be formed in semiconductor processes, are used.

[0081] Furthermore, in order to improve the adhesion between the metal layer 51 and the dielectric layer 52, an adhesion layer 57 may be formed on the metal layer 51, and the dielectric layer 52 may be formed on the adhesion layer 57. The method for forming the adhesion layer 57 is the same as the method for forming the adhesion layer 56, so a detailed explanation is omitted. For example, chromium (Cr) can be used to form the adhesion layer 57.

[0082] Next, a metal layer that will become the metal layer 53 is formed on the dielectric layer 52. The method for forming the metal layer that will become the metal layer 53 is the same as for the metal layer 51, so a detailed explanation is omitted. For forming the metal layer that will become the metal layer 53, a metal material is used that is composed of any metal selected from the set of copper (Cu), silver (Ag), and aluminum (Al), or a metal alloy containing at least one element selected from the above set.

[0083] Furthermore, in order to improve the adhesion between the dielectric layer 52 and the metal layer that will become the metal layer 53, an adhesion layer that will become the adhesion layer 58 may be formed on the dielectric layer 52, and a metal layer that will become the metal layer 53 may be formed on the adhesion layer. The method for forming the adhesion layer is the same as the method for forming the adhesion layer 56, so a detailed explanation is omitted. For example, chromium (Cr) can be used to form the adhesion layer.

[0084] Next, a metal layer that will form the protective layer 54 (hereinafter sometimes referred to as the "outermost metal layer") is formed on the metal layer that will form the metal layer 53. The method for forming the outermost metal layer is the same as for the metal layer 51, so a detailed explanation is omitted. For the formation of the outermost metal layer, a metal material is used that consists of any metal selected from the set of gold (Au), ruthenium (Ru), and iridium (Ir), or a metal alloy containing at least one element selected from the above set.

[0085] Next, a metal layer 53 (multiple metal bodies 55) and a protective layer 54 are formed by a photolithography process and an etching process. Specifically, a liquid resist is applied to the outermost metal layer using a spin coater or the like, and the applied liquid resist is dried to form a resist film (photoresist). Then, using an exposure device such as a KrF exposure machine or an electron beam lithography system, patterns corresponding to the metal bodies 55 are transferred to the resist film.

[0086] Then, the pattern transferred to the resist film is developed using a developing machine. Next, the metal layer that will form the metal layer 53 and the portion of the outermost metal layer that is not covered by the pattern are removed by ion milling, and then the resist film is removed with an organic solvent (NMP). This forms the metal layer 53 and the protective layer 54. As a result, the reflective layer 15 is formed on the substrate 50 as shown in Figure 11.

[0087] Next, as shown in Figure 12, a dielectric layer 61, which will serve as the basis for the dielectric spacer layer 16, is formed on the reflective layer 15. The method for forming the dielectric layer 61 is the same as that for the dielectric layer 52, so a detailed explanation is omitted. The thickness of the dielectric layer 61 is, for example, 80 nm.

[0088] Next, as shown in Figure 13, the dielectric layer 61 is planarized by a CMP (Chemical Mechanical Polishing) process. Ideally, the dielectric layer 61 on the protective layer 54 should be completely removed, but it is sufficient if the dielectric layer 61 is planarized. This forms the dielectric spacer layer 16. The distance from the top surface of the protective layer 54 to the top surface of the dielectric spacer layer 16, that is, the film thickness of the dielectric spacer layer 16 on the metal body 55, is 0 nm to 50 nm.

[0089] Next, as shown in Figure 14, a translucent layer 71, which will form the phase correction layer 17, is formed on the dielectric spacer layer 16. The translucent layer 71 is a layer made of a material that transmits visible light. The thickness of the translucent layer 71 is substantially equal to the height of the columnar body 17a.

[0090] Next, a phase correction layer 17 is formed by a photolithography process and an etching process. Specifically, a metal layer is formed by vacuum deposition using a method such as DC (Direct Current) sputtering. Then, a liquid resist is applied to the metal layer using a spin coater or the like, and the applied liquid resist is dried to form a resist film (photoresist). Then, using an exposure apparatus such as a KrF exposure machine and an electron beam lithography system, a resist pattern corresponding to the columnar bodies 17a is transferred to the resist film.

[0091] Then, the resist pattern transferred to the resist film is developed using a developing machine. Next, the portion of the metal layer not covered by the resist pattern is removed by an etching process, and then the resist pattern is removed. This forms a metal mask on the translucent layer 71. Then, the portion of the translucent layer 71 not covered by the metal mask is etched away to a depth corresponding to the height of the columnar body 17a by an etching process. After that, the metal mask is removed. This forms the phase correction layer 17.

[0092] As a result, a reflector 14 is formed on the surface 50a of the substrate 50 (see Figure 4).

[0093] By the method described above, multiple reflectors 14 are formed on a single substrate 50. Therefore, by cutting the substrate 50, a portion containing one reflector 14 is obtained. Then, by attaching this portion of the substrate 50 to a predetermined area on the inner surface 3a of the lens 3, a reflector 14 is formed on the inner surface 3a of the lens 3.

[0094] The reflector 14 may be formed directly on the inner surface 3a of the lens 3. The method for forming the reflector 14 on the inner surface 3a of the lens 3 is the same as the method for forming the reflector 14 on the surface 50a of the substrate 50. In this case, the reflector 14 is formed in a desired region on the inner surface 3a.

[0095] In the retinal projection device 10 described above, the reflection angle θ in the reflective layer 15 changes depending on the wavelength of the laser light Ls. r The laser light Ls is reflected as reflected light Lref, and the chromatic aberration of the reflected light Lref is corrected by the phase correction layer 17. Therefore, it is possible to reduce chromatic aberration.

[0096] To correct chromatic aberration, a corrective lens can be placed in the optical path of the laser beam Ls. In this case, the number of parts in the retinal projection device increases. In contrast, in the retinal projection device 10, the reflective layer 15 and the phase correction layer 17 are integrally formed, so there is no need to add external parts.

[0097] The phase correction layer 17 is a metalens containing a plurality of columnar bodies 17a that transmit visible light. With this configuration, when visible light passes through each columnar body 17a, a phase delay of the visible light occurs according to the size of the columnar body 17a. Therefore, chromatic aberration can be reduced by appropriately adjusting the amount of phase delay that occurs in each columnar body 17a.

[0098] The phase correction layer 17 may be composed of one compound selected from a set consisting of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride. Since these compounds are transparent in the visible light region, visible light transmittance of the phase correction layer 17 can be achieved. Because the absorption of visible light in the phase correction layer 17 is suppressed, the reflection efficiency for visible light can be increased.

[0099] The size of each columnar body 17a is set such that the phase of the red light Lr and the phase of the blue light Lb are in phase at the position where the columnar body 17a is installed. The maximum wavelength λ of the wavelength band used in the retinal projection device 10 max The wavelength λ of red light Lr red The minimum wavelength λ of the wavelength band used min The wavelength of blue light is λ blue Therefore, by making the phase of red light (Lr) and the phase of blue light (Lb) in the same phase, the maximum phase delay occurring in the wavelength band used can be eliminated. Consequently, chromatic aberration can be reduced.

[0100] The reflective layer 15 is a metamirror comprising a plurality of nanostructures (unit regions 40) provided along the inner surface 3a of the lens 3. Each nanostructure includes a metal layer 51, a dielectric layer 52, and a metal body 55, which are sequentially stacked in a direction intersecting (orthogonal) to the inner surface 3a. With this configuration, the reflective layer 15 can function as a reflective mirror due to electromagnetic resonance between the metal layer 51 and the metal body 55.

[0101] The reflective layer 15 has a reference wavelength λ ref A predetermined reflection angle θ r The configuration is such that the following can be obtained. Reflection angle θ in the reflective layer 15 r Since it changes depending on the wavelength λ, the reference wavelength λ ref By using this, the length Lx (the length of the metal body 55 in the X-axis direction) can be set.

[0102] Reference wavelength λ ref The wavelength λ of red light Lr is red This is also possible. In this case, the length Lx (length of the metal body 55 in the X-axis direction) can be increased, which facilitates the manufacture of the reflector 14.

[0103] The reflector 14 includes a dielectric spacer layer 16 provided between the reflective layer 15 and the phase correction layer 17. In this case, the provision of the dielectric spacer layer 16 allows the surface of the dielectric spacer layer 16 to be planarized by surface planarization treatment such as CMP.

[0104] The dielectric spacer layer 16 may be composed of one compound selected from a set consisting of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride. In this case, by using a material having the same or a similar refractive index as the phase correction layer 17, unwanted interfacial reflections can be suppressed.

[0105] The retinal projection device relating to this disclosure is not limited to the embodiments described above.

[0106] The method for determining the length Lx is not limited to the method described in the above embodiment. For example, the length Lx of the unit regions 40 located at both ends of the reflector 14 in the X-axis direction may be determined by the method described above, and the length Lx of the unit regions 40 located between them may be determined to change gradually from the length Lx of the unit region 40 located at one end of the reflector 14 in the X-axis direction to the length Lx of the unit region 40 located at the other end.

[0107] The metal body 55 is not limited to a single trapezoidal metal body, but may be composed of, for example, multiple metal bodies arranged in the X-axis direction.

[0108] The metal layer 51 and the metal body 55 may be composed of a transparent conductor. In other words, each nanostructure of the reflective layer 15 may include a first transparent conductor layer and a second transparent conductor layer instead of the metal layer 51 and the metal body 55. Each transparent conductor layer has excellent conductivity and high transparency in the visible light region. Examples of constituent materials for the transparent conductor layer include transparent conductive oxides (TCOs). Examples of TCOs include ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), FTO (Fluorine-doped Tin Oxide), and AZO (Aluminum-doped Zinc Oxide). In this case as well, similar to the metal layer 51 and the metal body 55, the reflective layer 15 can function as a reflective mirror due to electromagnetic resonance between the first transparent conductor layer and the second transparent conductor layer. Furthermore, the use of transparent conductor layers can reduce the possibility of obstruction of the view and improve visibility.

[0109] (Note) [Clause 1] A retinal projection device mounted on a near-eyewear device, A light source that emits laser light, A movable mirror that performs scanning with the aforementioned laser light, A reflector that reflects the laser light that has passed through the movable mirror and projects an image onto the retina of the user wearing the near eyewear device by irradiating the reflected light onto the retina, Equipped with, The reflector is A reflective layer that reflects the laser light at a reflection angle that changes depending on the wavelength of the laser light and emits it as reflected light, A phase correction layer for correcting the chromatic aberration of the reflected light, A retinal projection device, including a retinal projection device.

[0110] [Clause 2] The retinal projection apparatus according to Clause 1, wherein the phase correction layer is a metalens comprising a plurality of columnar bodies having visible light transmittance.

[0111] [Clause 3] The retinal projection apparatus according to Clause 2, wherein the phase correction layer is composed of one compound selected from the set of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

[0112] [Clause 4] The retinal projection apparatus according to Clause 2 or Clause 3, wherein the sizes of the plurality of columnar bodies are set such that the phase of red light and the phase of blue light are in the same phase at the positions where the columnar bodies are provided.

[0113] [Clause 5] The reflective layer is a metamirror comprising a plurality of nanostructures provided along the surface of the lens of the near eyewear device that faces the user's eyeball. The retinal projection apparatus according to any one of Clauses 1 to 4, wherein each of the plurality of nanostructures comprises a metal layer, a dielectric layer, and a metal body stacked in order in a direction intersecting the surface.

[0114] [Clause 6] The reflective layer is a metamirror comprising a plurality of nanostructures provided along the surface of the lens of the near eyewear device that faces the user's eyeball. The retinal projection apparatus according to any one of Clauses 1 to 4, wherein each of the plurality of nanostructures comprises a first transparent conductive layer, a dielectric layer, and a second transparent conductive layer stacked in order in a direction intersecting the surface.

[0115] [Clause 7] The retinal projection apparatus according to Clause 6, wherein the first transparent conductive layer and the second transparent conductive layer are made of ITO.

[0116] [Clause 8] The retinal projection apparatus according to any one of Clauses 5 to 7, wherein the reflective layer is configured to obtain a predetermined reflection angle with respect to a reference wavelength.

[0117] [Clause 9] The retinal projection apparatus according to Clause 8, wherein the reference wavelength is the wavelength of red light contained in the laser light.

[0118] [Clause 10] The retinal projection apparatus according to any one of the claims 1 to 9, wherein the reflector further includes a dielectric spacer layer provided between the reflective layer and the phase correction layer.

[0119] [Clause 11] The retinal projection apparatus according to Clause 10, wherein the dielectric spacer layer is composed of one compound selected from the set of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride. [Explanation of symbols]

[0120] 1...Near eyewear device, 3...Lens, 3a...Inner surface (surface), 10...Retinal projection device, 11...Light source unit (light source), 13...Movable mirror, 14...Reflector, 15...Reflective layer, 16...Dielectric spacer layer, 17...Phase correction layer, 17a...Columnar body, 51...Metal layer, 52...Dielectric layer, 55...Metal body.

Claims

1. A retinal projection device mounted on a near-eyewear device, A light source that emits laser light, A movable mirror that performs scanning with the aforementioned laser light, A reflector that reflects the laser light that has passed through the movable mirror and projects an image onto the retina of the user wearing the near eyewear device by irradiating the reflected light onto the retina, Equipped with, The reflector is A reflective layer that reflects the laser light at a reflection angle that changes depending on the wavelength of the laser light and emits it as reflected light, A phase correction layer for correcting the chromatic aberration of the reflected light, A retinal projection device, including a retinal projection device.

2. The retinal projection apparatus according to claim 1, wherein the phase correction layer is a metalens comprising a plurality of columnar bodies having visible light transmittance.

3. The retinal projection apparatus according to claim 2, wherein the phase correction layer is composed of one compound selected from the set of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

4. The retinal projection apparatus according to claim 2 or claim 3, wherein the sizes of the plurality of columnar bodies are set such that the phase of red light and the phase of blue light at the positions where the columnar bodies are provided are in the same phase.

5. The reflective layer is a metamirror comprising a plurality of nanostructures provided along the surface of the lens of the near eyewear device that faces the user's eyeball, The retinal projection apparatus according to any one of claims 1 to 3, wherein each of the plurality of nanostructures includes a metal layer, a dielectric layer, and a metal body stacked in order in a direction intersecting the surface.

6. The reflective layer is a metamirror comprising a plurality of nanostructures provided along the surface of the lens of the near eyewear device that faces the user's eyeball, The retinal projection apparatus according to any one of claims 1 to 3, wherein each of the plurality of nanostructures includes a first transparent conductive layer, a dielectric layer, and a second transparent conductive layer stacked in order in a direction intersecting the surface.

7. The retinal projection apparatus according to claim 6, wherein the first transparent conductive layer and the second transparent conductive layer are made of ITO.

8. The retinal projection apparatus according to claim 5, wherein the reflective layer is configured to obtain a predetermined reflection angle with respect to a reference wavelength.

9. The retinal projection apparatus according to claim 8, wherein the reference wavelength is the wavelength of red light contained in the laser light.

10. The retinal projection apparatus according to any one of claims 1 to 3, wherein the reflector further includes a dielectric spacer layer provided between the reflective layer and the phase correction layer.

11. The retinal projection apparatus according to claim 10, wherein the dielectric spacer layer is composed of one compound selected from a set consisting of silicon oxide, titanium oxide, tantalum oxide, and silicon nitride.

Images