Diffuse lighting system

Abstract

Embodiments of the present disclosure relate to diffuse lighting systems. A diffuse lighting system for reducing diffuse-related illumination nonuniformity includes an array of vertical cavity surface emitting laser (VCSEL) emitters and a diffuser element comprising a transparent substrate and an array of nanostructures. The size and shape of each nanostructure are configured to delay the phase of two orthogonal polarization states of light incident on each nanostructure from the emitter to reduce illumination nonuniformity in the output.

Description

Technical Field

[0001] The present application relates generally to lighting systems and, more particularly, to diffuse lighting systems. Background Art

[0002] Illumination systems, particularly laser-based systems that use diffusing elements, are subject to speckle in the illumination output. The speckle observed in the output is the result of interference generated when coherent illumination propagates through different paths of the diffusing element. Furthermore, efficient laser sources in mobile applications are often configured as multi-emitter laser arrays, such as vertical-cavity surface-emitting laser (VCSEL) arrays, which produce beams of high spectral purity, low divergence, and high coherence, thereby enhancing the intensity of the speckle pattern. Furthermore, beat frequencies can occur between the speckle patterns associated with individual VCSEL emitters, creating structured non-uniformities in the output illumination.

[0003] Typically, structured inhomogeneities, as observed on the illuminated target or imaged by the detector, have high frequencies. The beat pattern frequency is typically higher than that associated with speckle. For time-of-flight applications with resolutions less than a megapixel, the beat frequency of the speckle interference pattern in the illumination output that creates high-frequency structured inhomogeneities is not necessarily a problem, as the resolution of these sensor arrays may be too small to detect the structured inhomogeneities. However, as technological advances lead to increases in sensor resolution, such as megapixel density and higher, there is a need to mitigate the generation of inhomogeneities in the illumination output. Summary of the Invention

[0004] Embodiments of the present disclosure are directed to mitigating output illumination non-uniformity associated with diffuse illumination systems.Embodiments of the present disclosure may be used in conjunction with systems and methods for time-of-flight analysis and machine vision.

[0005] The present disclosure provides a polarization-dependent diffusing element that applies a non-uniform phase delay to the wavefront of light incident on the diffusing element by employing a plurality of patterned nanostructures. The plurality of patterned nanostructures delays a first orthogonal polarization state and a second orthogonal polarization state of the incident light. This has the effect of reducing the correlation of noise in a VCSEL system, thereby reducing the intensity of high-frequency structured illumination patterns caused by the beat frequency of the speckle pattern.

[0006] In an embodiment, a diffuse illumination system for reducing illumination non-uniformity associated with diffusion is provided, comprising an array of vertical cavity surface emitting laser (VCSEL) emitters. Each emitter has an emitting surface through which light is emitted. The system further comprises a diffusing element comprising a transparent substrate and an array of nanostructures. The transparent substrate has an upper surface and a lower surface. The lower surface of the transparent substrate is positioned on the emitting surface of each of a plurality of emitters, and the array of nanostructures is positioned on the upper surface of the transparent substrate. The size and shape of each nanostructure are configured to delay a phase of a first polarization state and a phase of a second polarization state of light incident on each nanostructure to reduce illumination non-uniformity. The first polarization state is orthogonal to the second polarization state, and light incident on each nanostructure is emitted by at least one emitter.

[0007] In another embodiment, a system is provided that includes a diffuse illumination system and further includes a processor, a lens system, and a detector. The processor is configured to trigger light emitted by a VCSEL emitter, and the light is directed toward a target via the lens system. The detector is configured to receive light reflected from the target via the lens system.

[0008] In another embodiment, the system is a time-of-flight camera.The processor is configured to determine a time of flight to a target based on the emitted and received light.

[0009] In another embodiment, the system is a machine vision camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a better understanding of the present disclosure, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0011] Figure 1 is a schematic diagram of a system for imaging a target according to an embodiment of the present disclosure;

[0012] Figure 2 According to an embodiment of the present disclosure Figure 1 A schematic diagram of the diffuse lighting components of the system;

[0013] Figure 3 shows the speckle pattern in the output of a conventional lighting system;

[0014] Figure 4 Two outputs of a conventional high-resolution illumination system are shown;

[0015] Figure 5 According to an embodiment of the present disclosure, Figure 2 a top view of an array of pillars on a transparent substrate; and

[0016] Figure 6 The embodiment according to the present disclosure is shown Figure 2 The output of the lighting system. DETAILED DESCRIPTION

[0017] In the following description, certain specific details are set forth to provide a thorough understanding of various aspects of the disclosed subject matter. However, the disclosed subject matter can be practiced without these specific details. In some instances, well-known structures and methods for manufacturing electronic devices, optical lenses, and sensors have not been described in detail to avoid obscuring the description of other aspects of the disclosure.

[0018] Unless the context requires otherwise, in the following description and claims, the word "comprise" and variations such as "include" and "comprising" are to be interpreted in an open, inclusive sense, ie, "including, but not limited to."

[0019] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, in one or more aspects of the present disclosure, the particular features, structures, or characteristics may be combined in any suitable manner.

[0020] It should be noted that the dimensions set forth herein are provided as examples. Other dimensions are contemplated for this and all other embodiments of the present application.

[0021] Figure 1 is a schematic diagram of a system 100 for imaging a target according to an embodiment of the present disclosure. In one embodiment, the system 100 is a time-of-flight camera.

[0022] Conventional time-of-flight systems are known to those skilled in the art and will not be discussed in detail. Conventional range imaging systems provide a time-of-flight camera that employs time-of-flight technology to resolve the distance between the camera and the subject (i.e., one or more points on an illuminated target) by measuring the round-trip time of a light signal provided by a laser or light emitting diode (LED). Systems can include radio frequency (RF) modulation systems that modulate a transmit beam with an RF carrier and then measure the phase shift of the received carrier beam, as well as direct time-of-flight systems that measure the direct flight time of a single laser pulse leaving the camera and reflecting back to the focal plane sensor array.

[0023] In another embodiment, system 100 is a machine vision camera. Conventional machine vision camera systems are known to those skilled in the art and will not be discussed in detail. The primary uses of machine vision are image-based automated inspection, classification, and robotic guidance. Machine vision refers to the ability of a computer to acquire and extract information from images on an automated basis. The imaging device (i.e., machine vision camera) can be separate from or combined with the main image processing unit. Including the complete processing functionality in the same housing as the camera is often referred to as embedded processing.

[0024] As shown, system 100 includes a diffuse illumination system 102, a lens system 104, a detector 106, and a processor 108. Illumination system 102 includes a vertical cavity surface emitting laser (VCSEL) emitter array 110 and a diffusing element 112. In one embodiment, processor 108 is configured to trigger light 114 generated and / or emitted by the emitters of VCSEL emitter array 110. Lens system 104 focuses emitted light 114 and may also assist an operator in directing emitted light 114 toward a target 116. System 100 is configured so that reflected light 118 (i.e., emitted light 114 reflected by target 116) is focused onto detector 106 upon returning through lens system 104. For a time-of-flight system 100, processor 108 is configured to determine a distance to target 116 based on the time of flight of emitted light 114 and received light 118. For the machine vision system 100, the processor 108 can be configured to further process the images captured by the detector 106 based on the specifications of the particular machine vision system 100. Although not shown, the system 100 may include one or more analog-to-digital converters (ADCs), digital-to-analog converters (DACs), signal processing software / hardware, memory, I / O interfaces, power supplies, and buses. The various components of such systems are well known in the art and will not be discussed in detail here.

[0025] The lens system 104 may include one or more optical components (e.g., lenses, spacers, filters). In an embodiment, the emitted light 114 and the reflected light 118 pass through the same components of the lens system 104, however, the scope of the present disclosure is a lens system 104 that includes two lens systems, a first lens system for focusing and / or directing the emitted light 114 and a second lens system for focusing and / or directing the reflected light 118. The first lens system and the second lens system may share one or more components, or may not share their respective components. As shown, the diffusing element 112 of the illumination system 102 may be in direct contact with the first surface 120 (also referred to as the upper surface) of the VCSEL emitter array 110. However, in alternative embodiments, an air gap (not shown) or a transparent spacer element (not shown) may be located between the upper surface 120 of the VCSEL emitter array 110 and the diffusing element 112. The air gap between the VCSEL emitter array 110 and the first surface 120 of the diffusing element 112 can be achieved by having appropriate mounting features on the mechanical housing (cover), attaching the diffusing element 112 to the mechanical housing (cover), and mounting the combination of the diffusing element 112 and the cover to the substrate 110 where the VCSEL emitters are located. In an embodiment of the present disclosure, the VCSEL emitter array 110 is configured as a two-dimensional (2D) VCSEL emitter array.

[0026] Figure 2 According to an embodiment of the present disclosure Figure 1 Schematic diagram of a diffuse lighting system 102. As will be described in more detail below, embodiments of the diffuse lighting system 102 reduce diffusion-related illumination non-uniformity present in conventional lighting systems having a diffuse element (also referred to as a light diffuser or simply a diffuser).

[0027] Illumination systems that include laser light sources, which emit light with a very narrow bandwidth and typically a small dispersion angle, often employ diffusers to help increase the dispersion angle so that the edges of far-field targets are adequately illuminated. However, one drawback of using a diffuser is the introduction of a speckle pattern into the illumination output, as observed on the illuminated target and / or imaged by the system's detector. Furthermore, depending on the layout and / or size of the laser light sources and the layout of the diffuser (e.g., diffusers are typically constructed from multiple segments (i.e., sub-diffusers or apertures) and therefore have a specific optical period), optical beats can occur between the speckle patterns created by each of the individual laser light sources, thereby generating a structured low-frequency noise pattern (i.e., a beat pattern) that is observed on the illuminated target and / or imaged by the system's detector.

[0028] For example, Figure 3A speckle pattern 302 is shown in the output 300 of a conventional illumination system. The speckle pattern 302 is caused by laser light (emitted by laser emitters positioned in a 2D array) passing through a diffuser element. The non-uniformity in the output 300 is clearly visible, as indicated by the unstructured variations 302 in the intensity of the output 300. Speckle occurs when some coherent light from a single laser emitter passes through a portion of the diffuser, but due to irregularities in the diffuser's manufacturing process, such as non-planar surfaces, variable width, non-uniform distribution of the material comprising the diffuser, and / or impurities introduced into the material comprising the diffuser during manufacturing (to name a few), takes different paths through the diffuser and then interferes with each other in constructive and destructive ways to produce the speckle pattern. This interference effect between the coherent light rays results in an unstructured pattern of illumination (i.e., a speckle pattern), in addition to the low-frequency beat pattern caused by the non-optimized optics / emitter array configurations found in conventional illumination systems.

[0029] Figure 4 Two outputs 402 and 404 of a conventional high-resolution illumination system are shown. The first output 402 shows a low-frequency beat pattern 406 formed by fringes, and the second output 404 shows a high-frequency beat pattern 408 formed by fringes. As shown, the high-resolution system not only resolves the structured low-frequency beat pattern 406, but the high-resolution illumination system also resolves the structured high-frequency beat pattern 408. Although not shown, a conventional low-resolution illumination system may not be able to resolve the structured high-frequency beat pattern 408.

[0030] Beat patterns 406, 408 (i.e., structured inhomogeneities in illumination) are generated when a beat occurs between speckle patterns associated with (i.e., produced by) individual laser emitters. That is, the angular coincidence of the speckle patterns results in a beat of the speckle patterns, thereby structuring the system's noise into a generally higher-frequency pattern, as shown. The frequency and intensity of the beat pattern can depend on one or more of the emitter array period (e.g., the periodic distribution of emitters in a 2D array (in one or two orthogonal directions)), the optical period of the diffuser, and the wavelength of the light.

[0031] Back to Figure 2, the diffuse lighting system 102 includes a VCSEL emitter array 110 having a substrate 202, VCSEL emitters 204, and a diffusing element 112. Each VCSEL emitter 204 includes an emitting surface 205 through which light generated by the emitter 204 propagates. The diffusing element 112 includes a transparent substrate 206 and an array 208 of nanostructures 210. The transparent substrate 206 has an upper surface 211 and a lower surface 212. In one embodiment, and as shown, the lower surface 212 of the transparent substrate 206 (i.e., a portion of the lower surface 212) is located on the emitting surface 205 of each of the plurality of emitters 204. However, as described above in conjunction with Figure 1 As described, a transparent spacer element (not shown) can be positioned on the emitting surface 205 of each of the plurality of emitters 204, and the lower surface 212 of the transparent substrate 206 can be positioned on the transparent spacer element (i.e., the transparent spacer element is positioned between the diffusing element 112 and the VCSEL emitter array 110).

[0032] Nanostructure array 208 is located on upper surface 211 of transparent substrate 206. In one embodiment, each nanostructure 210 extends from upper surface 211 in a direction perpendicular to upper surface 211. Nanostructures 210 will be discussed in more detail below. In alternative embodiments, each nanostructure 210 may extend perpendicularly from lower surface 212 toward VCSEL emitter array 110.

[0033] Emitter array 110 includes rows 214 of emitters 204 and columns 216 of emitters 204. In one embodiment, as shown, rows 214 are parallel to each other, columns 216 are parallel to each other, and the rows and columns are perpendicular to each other. However, the scope of the present disclosure encompasses 2D arrays formed by rows and columns of emitters at any angle to each other.

[0034] In one embodiment, adjacent emitters 204 in a row 214 of emitters 204 have a first pitch, and adjacent emitters 204 in a column 216 of emitters 204 have a second pitch. The scope of this disclosure encompasses the first pitch being equal to the second pitch, as well as the first pitch not being equal to the second pitch. For ease of description, rows 214 may be considered to be in an X direction 222 and columns 216 may be considered to be in a Y direction 224 in an XYZ orthogonal coordinate system 226, however, the scope of this disclosure encompasses arrays 110 having layouts of rows 214 and columns 216 in any two orthogonal directions or any two non-orthogonal directions. Thus, although the present disclosure may present some embodiments having X and Y pitches or X and Y rows / columns for ease of description, these embodiments include pitches and rows / columns formed in any two directions defined in a plane.

[0035] In one embodiment of the present disclosure, VCSEL emitters 204 emit light of approximately the same wavelength, within tolerances due to manufacturing inconsistencies and / or material defects (such as material impurities). In one embodiment, the light emitted by VCSEL emitters 204 has a wavelength of approximately 930 nm to 950 nm. In other embodiments, both the x-pitch 218 and the y-pitch 220 of emitter array 110 are approximately equal to or less than the wavelength of the light emitted by emitters 204.

[0036] In an embodiment, the transparent substrate 206 may be formed of glass, fused silica, or another dielectric material. In another embodiment, the nanostructures 210 may be formed of amorphous silicon, polycrystalline silicon, or other materials that exhibit a significant refractive index compared to the transparent sealant 230. As shown, the nanostructures 210 are separated by gaps 228. Although the gaps 228 are shown as having different sizes (i.e., different volumes), the gaps 228 between the nanostructures 210 may have the same uniform size.

[0037] In an embodiment, air fills the gaps 228 between the nanostructures 210. In another embodiment, the diffusing element 112 includes an optional transparent sealant 230. The transparent sealant 230 covers the array of nanostructures 210, thereby filling the gaps 228 between the nanostructures 210 with the sealant 230. In an embodiment, the transparent sealant is formed of silicon dioxide, however, the scope of the present disclosure encompasses transparent sealants formed of polymers, dielectrics, or other materials with a sufficiently low refractive index to exhibit an appropriate refractive index compared to the high refractive index nanostructures.

[0038] In an embodiment, the material forming the nanostructures 210 is selected such that the refractive index of the nanostructures 210 is higher than the refractive index of the material filling the gaps 228 between the nanostructures 210 (i.e., ambient air or the material forming the sealant) and the refractive index of the transparent substrate 206. In one embodiment, the refractive index of the nanostructures 210 is preferably at least 1.5 times greater than the refractive index of the material filling the gaps 228 between the nanostructures 210. This has the beneficial effect of increasing the polarization efficiency of the nanostructures 210. The polarization effect of the nanostructures will be discussed in more detail below.

[0039] In one embodiment of the present disclosure, the nanostructure array 208 includes rows 232 of nanostructures 210 and columns 234 of nanostructures 210. In one embodiment, and as shown, the rows 232 are parallel to each other, the columns 234 are parallel to each other, and the rows and columns are perpendicular to each other. However, the scope of the present disclosure encompasses 2D arrays of nanostructures 208 formed by rows and columns of nanostructures at any angle to each other.

[0040] In an embodiment, adjacent nanostructures 210 in a row 232 of nanostructures 210 have a third pitch, and adjacent nanostructures 210 in a column 234 of nanostructures 210 have a fourth pitch. The scope of this disclosure encompasses the third pitch 236 being equal to the fourth pitch 238, as well as the third pitch 236 not being equal to the fourth pitch 238. Furthermore, the third and fourth pitches can be fixed or variable. In an embodiment, the third and fourth pitches 236, 238 are less than or approximately equal to the wavelength of light emitted by the VCSEL emitter 204.

[0041] In another embodiment, the first pitch 218, the second pitch 220, the third pitch 236, and the fourth pitch 218 are each different from one another. In another embodiment, the first pitch 218 is greater than the third pitch 236 and the fourth pitch 238, and the second pitch 220 is greater than the third pitch 236 and the fourth pitch 238. In another embodiment, the first pitch 218 is equal to the second pitch 220, the third pitch 236 is equal to the fourth pitch 238, and the first pitch 218 and the third pitch 236 are different.

[0042] In an embodiment of the present disclosure, the size and / or shape of each nanostructure 210 is configured to delay the phase of the first polarization state and the phase of the second polarization state of light emitted from one or more emitters 204 and incident on the nanostructure 210 to reduce illumination non-uniformity. When light passes through the transparent substrate 206 and impinges on the nanostructure 210, the electric and magnetic fields of the incident light generate induced fields in the nanostructure 210, which then interact with the fields of the impinging light to polarize the light. This is particularly effective when the refractive index of the nanostructure 210 is greater than the refractive index of both the transparent substrate 206 and / or the material filling the gaps 228 between the nanostructures 210 (i.e., ambient air or the material constituting the sealant 230).

[0043] In an embodiment, light incident on each nanostructure 210 is emitted by at least one emitter 204. For example, in one embodiment, the layout of nanostructure array 208 is identical to the layout of emitter array 110. That is, directly beneath each nanostructure 210 is a single emitter 204, or in other words, the x and y pitches of nanostructure array 208 are equal to the x and y pitches of emitter array 110. In this embodiment, light incident on any given nanostructure 210 is emitted only by the emitter 204 directly beneath it. However, light incident on any given nanostructure 210 may be emitted by two or more emitters 204, depending on whether system 102 includes a rotatable transparent spacing element and / or depending on the XY dimensions (i.e., cross-sectional dimensions) of any given nanostructure 210 compared to the XY dimensions of the emitter 204 directly beneath it.

[0044] In other embodiments where at least one of the first pitch 218, the second pitch 220, the third pitch 236, and the fourth pitch 238 is different from the other pitches, light incident on some of the nanostructures 210 may be emitted by two or more emitters 204, and light incident on other nanostructures 210 may be emitted by only one emitter 204.

[0045] In one embodiment, the first polarization state is orthogonal to the second polarization state. For example, the first polarization state can be an S polarization state and the second polarization state can be a P polarization state, however, the scope of the present disclosure encompasses mixed-mode light (i.e., light comprising multiple polarization states, such as linear polarization, circular polarization (left and / or right)), elliptically polarized light (left-polarized light and right-polarized light), and unpolarized light emitted by emitter 204. P polarization refers to light polarized parallel to the plane of incidence (i.e., the plane of the incident light beam and the light beam scattered by nanostructures 210), and S polarization refers to light polarized perpendicular to the plane of incidence.

[0046] In one embodiment, the shape of each nanostructure 210 is defined as the shape of a cross-section of the nanostructure 210, where the cross-section is defined as being in a plane parallel to a surface of the transparent substrate 206, such as the lower surface 212 of the transparent substrate or the upper surface 211 of the transparent substrate 206 (i.e., the XY plane of the coordinate system 226). The size of the nanostructure 210 can be defined by one or more dimensions of the cross-section of the nanostructure 210, such as one or more of a radius, a perimeter, an area, a length of a side, and a length of a major axis and a minor axis of an elliptical cross-section. In another embodiment, the size can include parameters defining a three-dimensional aspect of the nanostructure 210, such as the height of the nanostructure measured perpendicular to the upper surface 210 of the transparent substrate 206 (i.e., measured in the Z direction of the coordinate system 226).

[0047] In one embodiment, the nanostructures 210 are pillars. In some embodiments, each pillar 210 has an elliptical, circular, square, or rectangular cross-section. In other embodiments, the height of the pillar 210 can be greater than at least one dimension of the pillar's cross-section, or the height can be less than each dimension of the pillar's cross-section. That is, the height of the pillar can be less than any lateral (i.e., XY) dimension of the pillar. Figure 2 As shown in the embodiment of FIG, the post has an elliptical cross-section 240.

[0048] In one embodiment, when the cross-sectional shape of the rod is circular or square, the phase of the first polarization state and the phase of the second polarization state are delayed by the same magnitude. The magnitude of the phase delay can be based on the dimensions of the cross-sectional shape, such as the diameter of a circle and the length of a side of a square. When the cross-sectional shape of the rod is elliptical (e.g., Figure 2When the cross-section of the first polarization state is elliptical or rectangular, the phase of the first polarization state and the phase of the second polarization state are delayed by different magnitudes. The magnitude of the phase delay is based on the lengths of the major and minor axes of the cross-section of the rod with an elliptical cross-section and the lengths of the sides of the cross-section of the rod with a rectangular cross-section.

[0049] In one embodiment, array 208 of pillars 210 includes pillars of varying shapes and / or sizes that are randomly selected. For example, the output of a random number generator can be used to randomly select the shape / size of pillars 210. The pillars 210 of array 208 are randomly selected, but are constrained to include at least some pillars having an elliptical cross-section, a rectangular cross-section, or a mixture of elliptical and rectangular cross-sections, and are selected to generate some S-polarized light and some P-polarized light from incident light, with at least some of the pillars acting to reduce the effects of speckle pattern beat frequency in the illumination output.

[0050] That is, the pillars 210 will act as polarization scatterers. Figure 2 In the exemplary embodiment of FIG, elliptical cylinders 210 have elliptical cross-sections 240 defined by a major axis in the x-direction 222 and a minor axis in the y-direction 224. Thus, these cylinders 210 will scatter incident light to generate P-polarized light. Other elliptical cylinders (not shown) having elliptical cross-sections defined by a major axis in the y-direction 224 and a minor axis in the x-direction 222 will scatter incident light to generate S-polarized light.

[0051] Figure 5 2 is a top view of a pillar array 502 on a transparent substrate 206 according to an embodiment of the present disclosure. As shown, the pillar array 502 includes a pillar 504, which is a large elliptical pillar having an elliptical cross-section defined by a major axis 506 in the Y direction 224 and a minor axis 508 in the X direction 222 (thereby generating S-polarized light), a pillar 510, which is a smaller elliptical pillar having an elliptical cross-section defined by a major axis 512 in the X direction 222 and a minor axis 514 in the Y direction 224 (thereby generating P-polarized light), and pillars 516 and 518, which are small and large circular pillars, respectively, having circular cross-sections defined by a first radius 520 and a second radius 522, respectively (thereby equally retarding the phases of the P and S polarization states).

[0052] Figure 6 1 shows the output 602 of the lighting system 102 according to an embodiment of the present disclosure. When compared to the outputs 402 and 404 of a conventional lighting system with a diffuser element, the output 602 of the lighting system 102 of the present disclosure shows a significant improvement in the uniformity of the diffuse illumination, including a significant reduction in the structured beat pattern, and a significant reduction in the speckle pattern, both of which can be seen in FIG. Figure 4 Observed in.

[0053] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above detailed description. Generally, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and claims, but should be construed to include all possible embodiments and the full range of equivalents to which such claims are entitled. Therefore, the claims are not limited by this disclosure.

Claims

1. A diffuse lighting system comprising: Vertical cavity surface emitting laser VCSEL substrate; a vertical cavity surface emitting laser (VCSEL) emitter array, located on the VCSEL substrate, each of the VCSEL emitters having an emitting surface through which light is emitted; as well as A diffusing element comprising a transparent substrate and a nanostructure array, wherein the transparent substrate is located on the VCSEL substrate and the emitting surface of the VCSEL emitter, the transparent substrate having a first surface facing the VCSEL substrate and a second surface opposite to the first surface, the transparent substrate covering each of the VCSEL emitters, and the nanostructure array being located on the second surface of the transparent substrate. The transparent substrate has a first refractive index, and the nanostructure array has a second refractive index greater than the first refractive index, wherein the size and shape of each nanostructure is configured to delay the phase of a first polarization state of light incident on each nanostructure, and to delay the phase of a second polarization state of light incident on each nanostructure, wherein the first polarization state is orthogonal to the second polarization state, and The light incident on each nanostructure is emitted by at least one VCSEL emitter in the VCSEL emitter array.

2. The system of claim 1 , wherein the array of VCSEL emitters comprises rows of emitters and columns of emitters, wherein adjacent emitters in each row of emitters are separated by a first pitch, wherein adjacent emitters in each column of emitters are separated by a second pitch, wherein the array of nanostructures comprises rows of nanostructures and columns of nanostructures, wherein adjacent nanostructures in each row of nanostructures are separated by a third pitch, and wherein adjacent nanostructures in each column of nanostructures are separated by a fourth pitch, wherein light emitted by the emitters of the array of VCSEL emitters has a wavelength, and wherein the third pitch and the fourth pitch are less than or equal to the wavelength. 3 . The system of claim 2 , wherein the lower surface of the transparent substrate is separated from the emitting surface of each VCSEL emitter in the array of VCSEL emitters by an air gap. The system of claim 2 , wherein the nanostructures are pillars. 5 . The system of claim 2 , wherein the first pitch, the second pitch, the third pitch, and the fourth pitch are different from one another.

6. The system of claim 2, wherein the first pitch is greater than the third pitch and the fourth pitch, and the second pitch is greater than the third pitch and the fourth pitch.

7. The system of claim 6, wherein the first pitch is equal to the second pitch, and the third pitch is equal to the fourth pitch.

8. The system of claim 1, wherein the transparent substrate is formed of glass, fused silica, or other dielectric material, and the nanostructures are formed of amorphous silicon, polycrystalline silicon, or other material exhibiting a greater refractive index than the transparent substrate.

9. The system of claim 1, wherein the diffusing element further comprises a transparent encapsulant, wherein the transparent encapsulant covers the array of nanostructures, and wherein the transparent encapsulant has a refractive index lower than a refractive index of the array of VCSEL emitters.

10. The system of claim 1, wherein the illumination non-uniformity comprises structured noise generated by a speckle pattern beat frequency, wherein the speckle pattern is generated by interference of light emitted from the emitter through the diffusing element.

11. The system of claim 10, wherein the first polarization state is an S polarization state and the second polarization state is a P polarization state.

12. The system of claim 11 , wherein the nanostructures are pillars separated from each other by gaps, wherein the gaps between the pillars comprise air or a transparent sealant material, wherein the pillars have a refractive index greater than both an index of refraction of air and an index of refraction of the transparent sealant material, and wherein the shape is a cross-sectional shape defined in a plane parallel to an upper surface of the transparent substrate, and wherein the size is a size of the cross-sectional shape.

13. The system of claim 12, wherein the cross-sectional shape of each post is one of: oval, circular, square, and rectangular.

14. The system of claim 13, wherein when the cross-sectional shape of the rod is one of the circular shape or the square shape, the phase of the first polarization state and the phase of the second polarization state are delayed by the same magnitude, wherein the value of the same magnitude is based on the diameter of the circle and the length of the side of the square.

15. The system of claim 13 , wherein when the cross-sectional shape of the rod is one of the ellipse or the rectangle, the phase of the first polarization state and the phase of the second polarization state are delayed by different magnitudes, wherein the values ​​of the different magnitudes are based on the values ​​of the major and minor axes of the ellipse and the lengths of the two sides of the rectangle.

16. The system of claim 13, wherein light emitted by the VCSEL emitter has a wavelength, wherein the shape and the size of each pillar are randomly selected, and wherein the size of each pillar is less than or equal to the wavelength.

17. The system of claim 1, wherein the size and shape of each nanostructure are configured to delay the phase of the first polarization state and the phase of the second polarization state of light incident on each nanostructure by the same magnitude.

18. The system of claim 1, wherein the size and shape of each nanostructure are configured to delay the phase of the first polarization state and the phase of the second polarization state of light incident on each nanostructure by different magnitudes.

19. A system for imaging a target, comprising: Diffuse lighting system, including Vertical cavity surface emitting laser VCSEL substrate; an array of vertical cavity surface emitting laser (VCSEL) emitters, located on the VCSEL substrate, each of the VCSEL emitters having an emitting surface through which light is emitted, and A diffusing element comprising a transparent substrate and a nanostructure array, wherein the transparent substrate is located on the VCSEL substrate and on the emitting surface of the VCSEL emitter, the transparent substrate having an upper surface and a lower surface opposite to the upper surface, the lower surface of the transparent substrate being located above the emitting surface of each of the VCSEL emitters, and the nanostructure array being located on the upper surface of the transparent substrate. wherein the transparent substrate has a first refractive index, and the nanostructure array has a second refractive index greater than the first refractive index, wherein the size and shape of each nanostructure is configured to delay the phase of a first polarization state of light incident on each nanostructure, and to delay the phase of a second polarization state of light incident on each nanostructure, wherein the first polarization state is orthogonal to the second polarization state, and wherein the light incident on each nanostructure is emitted by at least one VCSEL emitter in the array of VCSEL emitters; processor; lens system; as well as detector, where: The processor is configured to trigger light emitted by the VCSEL emitter, The lens system is configured to direct the light toward a target, and The detector is configured to receive light reflected from the target via the lens system.

20. The system for imaging a target of claim 19, wherein the system for imaging a target is a time-of-flight camera, and wherein the processor is configured to determine a time of flight to the target based on the emitted light and the received light.

21. The system for imaging a target of claim 19, wherein the system for imaging a target is a machine vision camera.

22. A diffuse lighting system comprising: Vertical cavity surface emitting laser VCSEL substrate; a vertical cavity surface emitting laser (VCSEL) emitter array, located on the VCSEL substrate, each of the VCSEL emitters being configured to emit light; as well as a diffusing element comprising a transparent substrate and a nanostructure array, wherein the nanostructure array is located on the transparent substrate, and the transparent substrate is located on the VCSEL substrate and the VCSEL emitter, The transparent substrate has a first refractive index, and the nanostructure array has a second refractive index greater than the first refractive index, wherein each nanostructure is configured to receive light from one or more of the VCSEL emitters and delay the phase of at least one of a first polarization state and a second polarization state of the received light, The first polarization state is orthogonal to the second polarization state.

23. The system of claim 22, wherein the diffusing element further comprises a transparent encapsulant covering the array of nanostructures, and wherein the transparent encapsulant has a refractive index lower than a refractive index of the array of VCSEL emitters.

Images