Single element dot pattern projector

Abstract

Disclosed herein is a single element dot pattern projector with meta-optics. The projector includes a laser light source and a metasurface chip integrated onto the laser light source. The metasurface chip includes a metasurface element that is spaced from the laser light source by a distance equal to the collimated functional focal length of the metasurface chip. The laser light source generates light that is diffracted through the metasurface element to generate the dot pattern. The meta-optics enabled projector leads to a unique way of integrating meta-optics and unique functionality that can be added to the dot pattern.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of and priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 63 / 192,962, entitled “Single Flat Optical Element Dot Pattern Projector,” filed May 25, 2021, which is incorporated by reference in its entirety for all purposes.

[0002] The present disclosure is directed to single-element dot pattern projectors involving metasurfaces (sometimes called meta-optics) and methods for forming dot patterns involving VCSEL arrays. [Background technology]

[0003] A metasurface dot pattern projector is an optical device that transforms a laser source or multiple laser sources into a large number of dots and collimates the output beam. Typically, the number of dots projected from the device exceeds that of a single or multiple laser sources, and the full width at half maximum (FWHM) of the divergence of the output light is targeted to be minimized. For example, a dot pattern projector can transform a vertical cavity surface emitting laser (VCSEL) with 20 individual laser apertures into 20×N dots, with each dot targeted to have an FWHM of less than 0.50 degrees.

[0004] Dot pattern projectors have some applications in 3D sensing, but nearly all 3D sensing dot projector modules in consumer applications utilize VCSEL sources. The details of the dot pattern projected onto a scene depend on the application in which the projector is being used. With time-of-flight (TOF) imaging, the target number of dots in the far field can be only 10 times the number of laser apertures. With structured light, in contrast, the number of projected dots can be 100 times the VCSEL aperture.

[0005] Due to the multiple goals of a dot pattern projector, namely to multiply the VCSEL pattern, to achieve a high degree of collimation at the laser output, and to minimize the overall form factor of the device, a dot pattern projector module typically consists of many individual optical components. For example, a standard dot projector module designed to fit into a mobile device requires at least one, and typically three, refractive lenses to collimate the laser light, and one diffractive optical element (DOE) that would replicate the baseline number of VCSEL apertures and generate the desired number of dots in the far field. The complexity of the module results in significant challenges for integration, and furthermore, the module thickness often exceeds the space available within the bezel of a phone, laptop, or display. The latter limitation leads to more complex integration schemes such as folded optical light paths. Summary of the Invention [Means for solving the problem]

[0006] This application is directed to single-element dot pattern projectors involving metasurfaces (sometimes called meta-optics) and methods for forming dot patterns involving VCSEL arrays.

[0007] Various embodiments of the present invention include a single element dot pattern projector that includes a laser light source and a Metasurface chip integrated onto the laser light source, the Metasurface chip including a Metasurface element spaced from the laser light source by a distance equal to the back focal length of the Metasurface chip, the laser light source generating light that is diffracted through the Metasurface element to generate the dot pattern.

[0008] In various other embodiments, the laser light source includes a vertical cavity surface emitting laser (VCSEL).

[0009] In yet various other embodiments, the VCSEL includes multiple individual laser apertures.

[0010] In still various other embodiments, the individual laser apertures are configured to output dots having a full width at half maximum (FWHM) of less than 0.5 degrees.

[0011] In still various other embodiments, the metasurface chip is configured to satisfy the following equation: [ka] and, [ka] where A is the alignment tolerance of the metasurface chip, θ is the circumferential angle where the laser source power drops to less than 0.5% of the total power, MSx is the width of the active area of ​​the metasurface chip in the x-direction, VCSELx is the width of the laser source in the x-direction, A is the estimated size of the laser source beam beyond VCSELx in the x-direction, and C is the gap size between the laser source and the metasurface chip, which is equal to the back focal length of the metasurface chip.

[0012] In still various other embodiments, the Metasurface tips have a tip width in the x-direction of Msx+2*Border, where Border is the size of the tip that exceeds the estimated size of the source beam in the x-direction.

[0013] In yet various other embodiments, the Metasurface chip is integrated above a laser light source such that the laser light source outputs light through the gap between the Metasurface element and the laser light source.

[0014] In still various other embodiments, the Metasurface chip is integrated above the back side of the laser light source such that light is output through the back side of the laser light source on the Metasurface chip.

[0015] In yet various other embodiments, the Metasurface chip is integrated above the front side of the laser light source such that light is output through the front side of the laser light source on the Metasurface chip.

[0016] In yet various other embodiments, the gap is provided by the substrate of the Metasurface chip.

[0017] In yet various other embodiments, the gap is provided by epoxy or air between the laser light source and the Metasurface element.

[0018] In still various other embodiments, the Metasurface elements are positioned on top of a substrate of a Metasurface chip.

[0019] In yet various other embodiments, the Metasurface chip provides both a lens function and a multiplication function to the light from the laser light source.

[0020] In yet various other embodiments, the Metasurface tip further provides a linear phase function to light from a laser light source.

[0021] In still various other embodiments, the dot pattern has an asymmetric pattern.

[0022] In yet various other embodiments, the laser source is integrated into the chip, and the laser source chip and the metasurface chip are integrated into a single monolithic module.

[0023] In yet various other embodiments, the Metasurface elements are organized into a plurality of hexagonal shaped tiles.

[0024] Additionally, many embodiments of the present invention include a method of forming a dot pattern using a laser light source, the method including providing a laser light source integrated into the chip, providing a metasurface chip including metasurface elements, integrating the laser light source chip and the metasurface chip such that the metasurface elements are spaced from the laser light source by a distance equal to the back focal length of the metasurface chip, and generating light from the laser light source that is diffracted through the metasurface elements to generate the dot pattern.

[0025] In various other embodiments, the laser light source includes a vertical cavity surface emitting laser (VCSEL).

[0026] In still various other embodiments, the metasurface chip is configured to satisfy the following equation: [ka] and, [ka] where A is the alignment tolerance of the metasurface chip, θ is the circumferential angle where the laser source power drops to less than 0.5% of the total power, MSx is the width of the active area of ​​the metasurface chip in the x-direction, VCSELx is the width of the laser source in the x-direction, A is the estimated size of the laser source beam beyond VCSELx in the x-direction, and C is the gap size between the laser source and the metasurface chip, which is equal to the back focal length of the metasurface chip.

[0027] In still various other embodiments, the Metasurface tips have a tip width in the x-direction of Msx+2*Border, where Border is the size of the tip that exceeds the estimated size of the source beam in the x-direction.

[0028] Additional embodiments and features are set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by practice of the present disclosure. A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings, which form a part of this disclosure. [Brief description of the drawings]

[0029] The description will be more fully understood with reference to the following figures, which are presented as exemplary embodiments of the invention and should not be construed as a complete recitation of the scope of the invention.

[0030] [Figure 1A] FIG. 1A provides a schematic diagram of a single meta-optical system positioned across a VCSEL array, according to an embodiment.

[0031] [Figure 1B] FIG. 1B provides a schematic diagram of a single meta-optical system integrated directly onto a back-side emitting VCSEL array die, creating a monolithic unit, according to an embodiment.

[0032] [Figure 1C] FIG. 1C provides a schematic diagram of a meta-optical system integrated into a front-side emitting VCSEL array die, according to an embodiment.

[0033] [Diagram 2] FIG. 2 provides a schematic diagram of the complete functionality produced by a single meta-optical system, according to an embodiment.

[0034] [Diagram 3] FIG. 3 provides a set of example design parameters for a meta-optical system that combines all three functions in a single planar layer, according to an embodiment.

[0035] [Figure 4] FIG. 4 provides a ray trace of the projection lens function of a meta-optical system, according to an embodiment.

[0036] [Diagram 5] FIG. 5 provides an example of a pattern designed for the IFOV of a meta-optics dot pattern projector, according to an embodiment.

[0037] [Figure 6] FIG. 6 provides a top view of a meta-optics die, according to an embodiment.

[0038] [Figure 7] FIG. 7 provides a schematic side view of a single meta-optics dot pattern projector, according to an embodiment.

[0039] [Figure 8] FIG. 8 provides an example of calculated meta-optics dimensions, according to an embodiment.

[0040] [Figure 9] FIG. 9 illustrates a cross-sectional view of a metasurface including metasurface pillars with a rectangular configuration.

[0041] [Figure 10] FIG. 10 illustrates a cross-sectional view of a metasurface including metasurface pillars with a distorted configuration.

[0042] [Figure 11] FIG. 11 provides measurements of a dot pattern formed by a single meta-optics dot pattern projector, according to an embodiment.

[0043] [Figure 12] FIG. 12 provides a dot pattern formed by a single meta-optic device, according to an embodiment.

[0044] [Figure 13A] FIG. 13A provides an example of a tiling pattern for a Metasurface chip, according to an embodiment.

[0045] [Figure 13B] FIG. 13B illustrates an example output from a Metasurface chip with a rectangular tiling pattern.

[0046] [Figure 13C] FIG. 13C illustrates an example output from a Metasurface chip with a hexagonal tiling pattern.

[0047] [Figure 14] FIG. 14 provides a schematic diagram of a segmented meta-optics dot pattern projector, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Detailed Description of the Invention Turning now to the drawings, disclosed herein is a single element dot pattern projector with a metasurface (sometimes referred to as meta-optics). Many embodiments describe various implementations of planar meta-optics as they relate to optimizing the performance of a dot projector module while significantly simplifying the system. In additional embodiments, the designs enabled by meta-optics lead to unique ways of integrating meta-optics and unique functionality that can be added to the dot pattern. Various embodiments also relate to forming dot patterns with VCSEL arrays as a source, however, it will be appreciated that the embodiments are also applicable to a variety of different laser light sources. For example, the laser light source may be a solid state laser or any laser system and optics.

[0049] The use of a flat meta-optic, according to embodiments, allows the system to be telecentric in object space (e.g., at the plane of the VCSEL aperture) and project the VCSEL aperture to infinity using only a single element. In various embodiments, the meta-optic can be designed to impart a relatively simple phase profile, described as a radial extension of the phase profile. Embodiments can also add multi-function designs to a single meta-optic. Such multi-function designs allow the optical system to impart three or more functions in a single metasurface layer.

[0050] In an exemplary embodiment, the lens function is provided as a diffractive function that creates M copies of each single VCSEL aperture in the same metasurface layer. This is in contrast to existing dot pattern projectors where the lens function may be provided by a separate refractive element and the replication function is provided by a diffractive optical element (DOE). In some embodiments, the lens function may be combined in a single metasurface, which also has a first diffractive function that creates N copies of the VCSEL aperture over a relatively narrow field of view (inner field of view, i.e., IFOV) and a second diffractive function that further creates P copies of the IFOV pattern over a larger field of view (outer field of view, i.e., OFOV). In such an embodiment, if the VCSEL array consists of Q apertures, the single meta-optic system may generate Q×N×P collimated points of light in the far field. As a result of combining the refractive and diffractive lens functions in a single metasurface layer, all optical functions for the dot pattern projector may be provided in the same plane, which may result in one focal length from the plane of the VCSEL.

[0051] This elimination of the refractive lens in a standard dot pattern projector provides a unique integration of the meta-optics with the underlying VCSEL array. A typical dot projector module includes an air gap between the VCSEL array and the refractive lens. However, in the embodiments described herein, the meta-optics can be directly integrated with the VCSEL array chip to create a monolithic module. Such direct integration can be accomplished with a front-side emitting VCSEL. Epoxy can be utilized to bond the meta-optics die to the VCSEL array. In some embodiments, the meta-optics can be integrated onto a back-side emitting VCSEL array. In this implementation, integration can be accomplished through oxide bonding, a layer transfer process, or with an optically clear epoxy.

[0052] In many embodiments, the planar meta-optic is at a distance from the VCSEL equal to the back focal length of the metasurface elements on the metasurface chip. Thus, in such devices, the multiplication function and focal length of the collimating lens may be coplanar. For example, both functions may be provided in a single metasurface at the same distance from the VCSEL array. This is in contrast to standard dot pattern projectors, in which the focal length of the collimating lens may be in a different plane than the multiplication function. For example, the lens function may be at a focal length distance away from the VCSEL array plane, while the diffractive optical element, providing the multiplication function, may be at an additional displacement from the refractive lens and in a separate plane from the refractive lens. Furthermore, in contrast to the embodiments described herein, in standard dot pattern projectors, the light incident on the diffractive optical element (DOE) (e.g., the optics performing the pattern multiplication) may already be collimated by a separate refractive lens or lenses. However, for a single meta-optic dot pattern projector, because there are no other collimating or lensing elements prior to the light being incident on the meta-optic, the light incident on the meta-optic (which is also the plane of the multiplication function) may diverge with the same divergence angle as the VCSEL, and the chief ray angle of the light may be 0 degrees at all points along the meta-optic. The light incident on the meta-optic may not be separately collimated prior to being incident on the meta-optic.

[0053] In some embodiments, a single meta-optics dot projector may include a large module field of view (FOV) compared to a conventional projector. In this example, the diagonal module FOV may be as large as 150 degrees. The inclusion of flat optics may enable the meta-optics dot projector to bend light at high angles. As light is bent at high angles, the multi-level DOE may have significant vignetting caused by the different physical heights. In contrast to a multi-level DOE, the meta-optics may only have a single physical height.

[0054] Implementing a dot projector with meta-optics also allows additional unique functionality to be imparted to the device. In conventional dot projectors, including standard optics, the dots in the projected dot pattern may not be polarized or all dots may have nominally the same polarization (e.g., no preferred polarization). In some embodiments, a meta-optics dot pattern projector may allow the polarization of each individual dot to be controlled. In such embodiments, a metasurface dot pattern projector takes either unpolarized, partially polarized, or single-polarized light input from a VCSEL array and converts the output light into two arbitrary orthogonal polarization states. In some embodiments, the dot pattern may be separated into two preferred polarizations for the left and right halves of the projected pattern. Alternatively, a dot or all columns of neighboring dots may have opposite polarizations. In one specific case, the two polarizations of the dots may be left and right circular polarizations. In some embodiments, the meta-optics may convert the output light into more than two polarization states.

[0055] Specifically, in various embodiments of dot pattern projectors in structured light applications, it may be advantageous to project random or pseudo-random output patterns onto a scene. Such randomness may be achieved through introducing random distribution in the placement of VCSEL apertures in a VCSEL array. A dot pattern may then be generated through replicating the random array of VCSEL apertures in the far field. This method is typically implemented due to limitations in the functionality of multiplication DOEs used in conventional dot pattern projectors. In some embodiments, the metasurface dot projectors described herein allow full control of the phase of light from 0 to 2pi in a single flat optical plane. This allows the metasurface to impart asymmetric and arbitrary patterns compared to binary diffraction, which can only generate symmetric patterns or multi-level DOEs, which require multiple physical heights in the underlying structure to generate a 0 to 2pi phase shift. The meta-optics system allows an arbitrary radiation pattern to be transformed into a different outgoing arbitrary radiation pattern. Thus, when a single meta-optic is used in a dot pattern projector, a random dot array collimated in the far field using a VCSEL array can be generated using a regular grid (e.g., non-random) of VCSEL apertures. Importantly, the meta-optic can generate a dot pattern in the far field that is random across the entire module FOV. In a conventional dot pattern projector, by contrast, each individual tile can have a random array of dots, but the random array can be repeated.

[0056] In a conventional dot projector, the desired module FOV and the number of times the pattern can be multiplied (e.g., the number of dots generated in the far field) can set the projection FOV. Given this fact from standard paraxial optics, the number of pattern replicas can set the total track length of the module. In some embodiments, a single meta-optics system can directly transform a regular VCSEL array into a far-field pattern, which can remove this limitation. Instead, the module FOV can directly set the total track length, allowing for significantly thinner modules.

[0057] In some embodiments, it may be desirable for the projected dot pattern to be distorted along a certain angular direction. In particular, the field of view of a standard dot projector may be symmetric about the optical axis. However, in some embodiments, it may be desirable to optically, rather than mechanically, compensate for cases where the optical axis of the dot projector is not orthogonal to the object plane. In some embodiments, a meta-optics dot pattern projector may include an additional linear phase function, e.g., φ(x)=Ax, where x is a Cartesian coordinate and A is a phase constant, in addition to the lens and pattern multiplication functions. Again, from a standard dot projector, such asymmetry cannot be introduced. However, by using a single meta-optics approach according to embodiments, designs with arbitrary asymmetry to the output FOV can be included.

[0058] The general design freedom of the meta-optics approach, according to embodiments, also allows for unique aspects to be imparted on the individual tiles of the dot pattern itself. Specifically, meta-optics-enabled projections can allow each tile to have a different focal length, dot size, unique wavefront, or tilt to the wavefront. Such freedom allows for unique optimization of tiles at larger angles in the module's field of view compared to those at smaller angles in the field of view. The ability to optimize each individual tile also allows each tile to have a unique pattern on the inner field of view. This allows, for example, to uniquely define dot densities in different regions of the illumination field.

[0059] Exemplary embodiments The following embodiments are provided by way of example and should not be construed as limiting the scope of the present disclosure.

[0060] 1A illustrates a single meta-optic dot projector according to one embodiment of the present invention. The projector includes a VCSEL 104 and a metasurface chip 102 positioned over the VCSEL 104. A gap 106 is positioned between the VCSEL 104 and the Metasurface chip 102 such that light from the VCSEL 104 is output through the gap 106 on the Metasurface chip 102. The gap 106 may be air. The Metasurface chip 102 may include a metasurface, which both focuses and doubles the light from the VCSEL 104 to generate a dot pattern 108. The VCSEL 104 may be a front-side emitting VCSEL.

[0061] FIG. 1B illustrates a single meta-optic dot projector according to an embodiment of the present invention. The operation of the projector in FIG. 1B is similar to that in FIG. 1A. The VCSEL 104a may be a back-side emitting VCSEL, which may output light out of the back side of the VCSEL 104a. The Metasurface chip 102a may include a substrate, which may directly contact the VCSEL 104a, and may create a gap between the metasurface 110a of the Metasurface chip 102a and the VCSEL 104a.

[0062] FIG. 1C illustrates a single meta-optic dot projector according to one embodiment of the present invention. The operation of the projector of FIG. 1C is similar to that of FIG. 1B. In addition, the projector of FIG. 1C includes many components numbered the same as the projector of FIG. 1B. The description of these components will not be repeated in detail. The VCSEL 104 may be a front-side-output VCSEL, similar to the projector described in connection with FIG. 1A.

[0063] Advantageously, the metasurface chip may be directly integrated with a back-side or front-side emitting VCSEL array die to create a monolithic unit. The VCSEL 104, 104a may output light with a wavelength of 940±10 nm or 850±10 nm.

[0064] FIG. 2 shows a schematic diagram of the complete functions generated by a single meta-optic dot projector, according to an embodiment of the present invention. The collimation function of the single meta-optic can generate a projection with a horizontal field of view (HFOV). The meta-optic also generates an inner dot pattern with an inner horizontal field of view (IHFOV). The IHFOV is generally much narrower than the projected HFOV. The IHFOV and projected HFOV may be replicated by a third function, a tiling function. The tiling HFOV is shown on the schematic diagram. The combination of these three functions gives the dot projector a fully modular HFOV, shown on the schematic diagram. In various embodiments, all these functions can be achieved by a single meta-optic in a single plane within the module. FIG. 3 shows an exemplary set of design parameters for a meta-optic that combines all three functions in a single planar layer, according to an embodiment.

[0065] FIG. 4 provides a ray trace of a meta-optic projection lens functioning, according to an embodiment. As can be seen from the image, it is possible to achieve telecentric performance with a flat meta-optic. This is important for the functioning of a dot projector, especially in achieving a high degree of off-axis collimation. The lens uses a relatively simple radial phase expansion, in this example utilizing only up to the sixth order terms. However, in some embodiments, higher order terms can be added, if desired.

[0066] FIG. 5 provides an example of a pattern designed for IHFOV of a meta-optics dot pattern projector, according to an embodiment. In this example (meaning to be illustrative, not limiting), IHFOV can be achieved by choosing a diffraction grid of 3×5 diffraction orders. Within this grid, some orders are designed to be “on” and some orders are designed to be “off”; “on” the grid will have a certain light intensity, and “off” the grid will have substantially little or ideally no light intensity. In some embodiments, it may be advantageous for there to be some rotational symmetry for the “on” orders. Such symmetry facilitates certain important performance metrics, such as minimizing stray light and increasing dot contrast.

[0067] FIG. 6 is a schematic diagram of a top view of a Metasurface chip according to an embodiment of the present invention. Unlike conventional refractive lenses, which are generally radially symmetric, the Metasurface chip may be square or rectangular in shape. The Metasurface chip 600 may include an active area 602 surrounded by a boundary 604. The active area 602 may include various Metasurface elements. The Metasurface chip may also include orientation and alignment fiducial marks 606, which may be used during fabrication of the chip. The active area 602 may include an X dimension MSx and a Y dimension MSy. MSx and MSy may be determined by the VCSEL divergence and the total track length (TTL).

[0068] The metasurface elements may include high index structures, which are integrated on the substrate. The metasurface elements may be high index structures, which are embedded in a dielectric material. For example, the metasurface elements may include a high index dielectric (e.g., silicon) embedded in a low index dielectric (e.g., SiO2). The high index structures may be pillars, which are positioned on the substrate. The pillars may have a number of cross sections, including circular, rectangular, and / or cross-shaped. The pillars may have a high aspect ratio. The pillars may have a height of 600 nm to 800 nm. In some embodiments, the pillars may have a height of about 700 nm. The pillars may have a diameter of 80 nm to 300 nm. Examples of metasurface elements are disclosed in U.S. Patent Publication No. 2019 / 0064532, entitled "Transmissive Metasurface Lens Integration," filed August 31, 2018, which is incorporated by reference in its entirety for all purposes. In some embodiments, an antireflective layer may be positioned above and / or below the Metasurface elements.

[0069] 7 provides a schematic side view of a single meta-optics dot pattern projector including the metasurface chip 600 of FIG. 6. The projector includes a VCSEL array 702, which emits light with a certain beam width including a divergence angle θ. The VCSEL 702 may be spaced apart from the metasurface chip by a distance equal to the back focal length C of the metasurface chip, which may be equal to the focal length. Given the back focal length C, the VCSEL divergence angle θ and the VCSEL array dimension VCSELx may result in certain dimensions for the metasurface chip 600. These dimensions may be calculated by the following equations: [ka] B may be the alignment tolerance of the metasurface chip 600, which may be 25 μm. The divergence angle θ may be the circumferential angle at which the VCSEL power drops to less than 0.5% of the total power. MSx may be the width of the active area of ​​the metasurface chip in the x-direction. VCSELx may be the width of the light source in the x-direction. A may be the estimated size of the light source beam beyond VCSELx in the x-direction. Border is the size of the chip beyond the estimated size of the light source beam in the x-direction.

[0070] The dimensions of the VCSEL array 702 can provide a unique mapping to the Metasurface chip 600 dimensions. Certain Metasurface chip 600 dimensions can be chosen to maximize the amount of light that falls on the Metasurface chip 600, but the dimensions can also be made substantially smaller to produce a smaller meta-optics size at the expense of power that is lost from the VCSEL array 702 and not projected onto the dot pattern. As can be seen, unlike conventional dot pattern projectors, the light that is incident on the plane of the multiplication feature can be diverged by a divergence angle θ. FIG. 8 provides an example of calculated Metasurface chip 600 dimensions, according to an embodiment.

[0071] The metasurface may have a lattice or pitch. A unit cell may be defined as a single pillar of the metasurface, and the pillars may be spaced center-to-center by the unit cell lattice or pitch. The diameter of the pillars may vary, which gives the metasurface its function. In general, two basis vectors define the lattice on which the metasurface is defined. The spacing or pitch may be sub-wavelength λ / 2. A supercell serves to define the tiling function of the metasurface, and is also defined by the basis vectors. Given a target diffraction angle, the supercell basis vector is the reciprocal lattice vector of the target wave vector. The target diffraction angle may be the target wave vector.

[0072] The unit cell pitch may be chosen such that an integer multiple of the unit cell is equal to the target diffraction angle pitch. In the simplest case, this satisfies the following equation: [ka] N is an integer value. unitcell is the unit cell lattice, suepercell is the target diffraction angle lattice. When we go through the diffraction grating equation, the lattice suepercell can be calculated from the target angle through the following equation: [ka] n is the refractive index of the medium, λ is the design wavelength, and θ target is the target diffraction angle. In the general case, higher order diffraction angles can be targeted such that the following equation is satisfied: [ka] M is an integer number that labels the targeted diffraction order.

[0073] Since the unit cell lies on a 2D lattice, in general the lattice supercell constraint can be satisfied such that the following equation is satisfied: [ka] The lattice vectors may not be orthogonal or aligned in the x or y directions. N1, N2, N3, and N4 are all integers.

[0074] In the rectangular case, the unit cell lattice can be (400 nm, 0 nm) and (0 nm, 300 nm), which are mapped to supercell lattices of (1,600 nm, 0 nm) and (0 nm, 900 nm) with integer multiples (4, 0) and (0, 3), respectively. FIG. 9 illustrates a cross-sectional view of a metasurface including metasurface pillars with a rectangular configuration. As shown, the unit cell lattice 902 can be (400 nm, 0 nm) and (0 nm, 300 nm), and the supercell lattice 904 can be (1,600 nm, 0 nm) and (0 nm, 900 nm). The integer multiples can be (4, 0) and (0, 3), respectively.

[0075] In the case of distortion, the unit cells can be (400 nm, 0 nm) and (100 nm, 200 nm), which are mapped to supercell lattices of (1,600 nm, 0 nm) and (0 nm, 800 nm) with integer multiples of (4, 0) and (-1, 4), respectively. FIG. 10 illustrates a cross-sectional view of a metasurface including metasurface pillars with a distortion configuration. As shown, the unit cell lattice 1002 can be (400 nm, 0 nm) and (100 nm, 200 nm), and the supercell lattice 1004 can be (1,600 nm, 0 nm) and (0 nm, 800 nm). The integer multiples can be (4, 0) and (-1, 4), respectively.

[0076] FIG. 11 illustrates an example measurement of a dot pattern formed by a single meta-optics dot pattern projector described herein, according to an embodiment. The inset image shows a close-up of the central region of the projected dot pattern. Such a dot projector can have 40,000-50,000 individual dots projected from a VCSEL array with a significantly smaller aperture. The dot pattern, in this case, is a random array of dots typically projected as used in structured light applications.

[0077] 12 illustrates an example dot pattern formed by a single meta-optics dot pattern projector described herein, according to an embodiment. The dot pattern is a regular array of dots, here with approximately 1,000 unique dots projected from a VCSEL array with significantly fewer dots. Such dot patterns may be used in a variety of applications, such as time-of-flight cameras.

[0078] FIG. 13A provides an example of a tiling pattern for a metasurface chip, according to an embodiment. As shown, the metasurface chip may include a hexagonal tiling pattern 1102. Instead of rectangular tiling, the diffraction orders may be tiled into a hexagonal array. If the VCSEL chip also has hexagonal boundaries, dots may be tiled in the far field. Standard dot projectors may project light that becomes significantly distorted at the edges of the field of view. Light at the corners is generally not imaged onto the image sensor and is therefore wasted. From a meta-optics dot pattern projector, the projected pattern can be shared so that a larger fraction of the projected light will fall on the image sensor.

[0079] FIG. 13B illustrates an example output from a Metasurface chip with a rectangular tiling pattern. The output may include pincushion distortion. The output may be imaged by an image sensor 1104. As shown, there may be wasted light 1106 that travels beyond the image sensor 1104. FIG. 13C illustrates an example output from a Metasurface chip with a hexagonal tiling pattern. An example hexagonal tiling pattern is illustrated in FIG. 13A. The output may include pincushion distortion. The output may be imaged by an image sensor 1104. As shown, there may be wasted light 1106 that travels beyond the image sensor 1104. However, the wasted light 1106 may be less than the Metasurface chip with a rectangular tiling pattern illustrated in FIG. 13B. With judicious tiling and design choices, the wasted light 1106 may be minimized. This may not be possible using a typical dot projector, which has a fixed size lens.

[0080] FIG. 14 provides a schematic diagram of a segmented meta-optics dot pattern projector, according to an embodiment. As shown, a VCSEL array may output light toward a meta-optics system, which includes a substrate 1202 and a meta-optics microlens array 1204. In such a case, the VCSEL light is incident on the meta-optics microlens array 1204. However, in this embodiment, the meta-optics microlens array 1204 may be segmented with sub-sections 1204a. Each sub-section may be uniquely designed to impart a specific function to the output wavefront. For example, each sub-section 1204a may include an additional phase gradient, which may be placed on the output light. Such an implementation may lead to a substantially thinner module.

[0081] Doctrine of Equivalents Thus, while the invention has been described in certain specific aspects, many additional modifications and variations will become apparent to those skilled in the art. It is therefore to be understood that the invention can be practiced otherwise than as specifically described. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive.

Claims

1. 1. A single element dot pattern projector, comprising: a laser light source; a metasurface chip integrated onto the laser light source, the metasurface chip including metasurface elements spaced apart from the laser light source by a distance equal to a back focal length of the metasurface chip, the laser light source generating light that is diffracted through the metasurface elements to generate a dot pattern; Equipped with The metasurface tip is configured according to the following equation: [Equation 1] and, [Equation 2] and B is the alignment tolerance of the metasurface tip, θ is the surrounding angle at which the laser source power drops to less than 0.5% of the total power, where MSx is the width of the active area of ​​the Metasurface chip in the x-direction, VCSELx is the width of the laser light source in the x-direction, A is the estimated size of the laser light source beam beyond VCSELx in the x-direction, and C is the gap size between the laser light source and the Metasurface chip, which is equal to the back focal length of the Metasurface chip.

2. 10. The projector of claim 1, wherein the laser light source comprises a vertical cavity surface emitting laser (VCSEL).

3. The projector of claim 2 , wherein the VCSEL comprises a plurality of individual laser apertures.

4. 4. The projector of claim 3, wherein the individual laser apertures are configured to output dots with a full width at half maximum (FWHM) of less than 0.5 degrees.

5. 2. The projector of claim 1, wherein the Metasurface tips have a tip width in the x-direction of MSx+2*Border, where Border is the size of the tip that exceeds the estimated size of the light source beam in the x-direction.

6. The projector of claim 1 , wherein the Metasurface chip is integrated above the laser light source such that the laser light source outputs light through a gap between the Metasurface element and the laser light source.

7. 7. The projector of claim 6, wherein the Metasurface chip is integrated above a back side of the laser light source such that light is output through the back side of the laser light source onto the Metasurface chip.

8. 7. The projector of claim 6, wherein the Metasurface chip is integrated above a front side of the laser light source such that light is output onto the Metasurface chip through the front side of the laser light source.

9. The projector of claim 6 , wherein the gap is provided by a substrate of the Metasurface chip.

10. The projector of claim 6 , wherein the gap is provided by epoxy or air between the laser light source and the Metasurface element.

11. The projector of claim 1 , wherein the Metasurface elements are positioned on top of a substrate of the Metasurface chip.

12. The projector of claim 1 , wherein the Metasurface chip provides both a lens function and a multiplication function to the light from the laser light source.

13. The projector of claim 12 , wherein the Metasurface chip further provides a linear phase function to the light from the laser light source.

14. The projector of claim 1 , wherein the dot pattern has an asymmetric pattern.

15. The projector of claim 1 , wherein the laser light source is integrated into a chip, and the laser light source chip and the Metasurface chip are integrated into a single monolithic module.

16. The projector of claim 1 , wherein the Metasurface elements are organized into a plurality of hexagonal shaped tiles.

17. 1. A method for forming a dot pattern using a laser light source, the method comprising: providing the laser light source integrated into a chip; providing a Metasurface chip including Metasurface elements; integrating the Metasurface chip with the laser source chip such that the Metasurface elements are spaced from the laser source by a distance equal to a back focal length of the Metasurface chip; generating light from the laser light source that is diffracted through the Metasurface elements to generate the dot pattern; Including, The metasurface tip is configured according to the following equation: [Equation 3] and, [Equation 4] and B is the alignment tolerance of the metasurface tip, θ is the surrounding angle at which the laser source power drops to less than 0.5% of the total power, where MSx is the width of the active area of ​​the Metasurface chip in the x-direction, VCSELx is the width of the laser light source in the x-direction, A is the estimated size of the laser light source beam beyond VCSELx in the x-direction, and C is the gap size between the laser light source and the Metasurface chip equal to the back focal length of the Metasurface chip.

18. 20. The method of claim 17, wherein the laser light source comprises a vertical cavity surface emitting laser (VCSEL).

19. 18. The method of claim 17, wherein the Metasurface tip has a tip width in the x-direction of MSx+2*Border, where Border is the size of the tip that exceeds the estimated size of the source beam in the x-direction.

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