Light sources, sensors, and methods of illuminating scenes

Abstract

A light source includes an array (20) of vertical cavity surface emitting lasers (VCSELs) (22). The array (20) includes at least two sub-arrays (24), each sub-array (24) including at least one VCSEL (22). The sub-arrays (24) are offset relative to each other along a first axis (y). The sub-arrays (24) are configured to emit light independently of light emission from one or more other sub-arrays (24). The light source includes an optical component (26) configured as a single optical element. The optical component is configured to transform light emitted by the sub-arrays (24) into substantially parallel illumination lines (14) in a target area (16). The illumination lines are arranged along the first axis (y). Each illumination line (14) has a width in the direction of the first axis (y) and a length in the direction of a second axis (x) perpendicular to the first axis (y), wherein the width is less than the length.

Description

Technical Field

[0001] The present invention relates to a light source comprising a vertical cavity surface emitting laser (VCSEL) as a light emitting element. The present invention also relates to a sensor having a light source. The present invention also relates to a method for illuminating a scene, in particular for sensing applications. Background Art

[0002] Light sources including VCSEL arrays can be used as lighting devices, for example for infrared illumination. Using short pulses, VCSEL arrays can be used in sensors for time-of-flight applications. Such applications include, for example, short-range gesture recognition and 3D spatial recognition for portable devices. Currently envisioned VCSEL arrays have an area of approximately 1 mm. 2 , with an output power in the range of 1-10W. A specific illumination field can be defined by the application of the sensor, such as a time-of-flight camera observing a field of, for example, 70°x50°. For a standard time-of-flight camera, uniform illumination with a fast pulse pattern is desired. Advanced time-of-flight methods can use additional addressable illumination zones to provide higher peak powers and reduce the power consumption of the signal readout. For example, this allows better distance measurement accuracy or longer ranges compared to standard methods. Currently, there is no light source that is able to create uniform, individually addressable zones with simple, low-cost optics and a small build height. In contrast, prior art light sources require complex, bulky optics and / or moving parts, such as MEMS mirrors.

[0003] US 2018 / 0143012 discloses a device having a curved array of individually addressable light-emitting elements for sweeping across an angular range. The device also includes a curved optical element concentric with the curved array of light-emitting elements. The curved optical element is arranged to focus light emitted from each individually addressable light-emitting element to produce a substantially linear illumination pattern.

[0004] US 2018 / 0288388 A1 discloses a projector for incrementally projecting a dot or speckle pattern onto a scene within the FOV of an image sensor. Summary of the Invention

[0005] It is an object of the present invention to provide a light source with which homogeneous, individually addressable illumination areas can be created.

[0006] Another object of the present invention is to provide a light source that is low cost and has a small build height and has simple optics that are not bulky and require no moving parts.

[0007] Another object is to provide a sensor having a light source.

[0008] Another object of the present invention is to provide a method of illuminating a scene.

[0009] According to a first aspect, a light source is provided, comprising: a vertical cavity surface emitting laser (VCSEL) array, the array comprising at least two sub-arrays, each sub-array comprising at least one VCSEL, the sub-arrays being offset relative to each other along a first axis, the sub-arrays being configured to individually emit light; and an optical member configured as a single optical element and configured to transform the light emitted by the sub-arrays into substantially parallel illumination lines in a target area, wherein the illumination lines are arranged along the first axis, each illumination line having a width in the direction of the first axis and a length in the direction of a second axis perpendicular to the first axis, wherein the width is less than the length. If each of the sub-arrays has more than one VCSEL, the VCSELs of the sub-arrays are arranged along the second axis.

[0010] The optical member may be a transmissive optical member, and may be configured as a lens having a curved surface, or a diffraction element, or a GRIN (Gradient Index) lens, or a super lens.

[0011] According to the present invention, a light source is provided that uses a VCSEL array in conjunction with an optical component to illuminate a scene, wherein the illumination comprises several individually addressable illumination lines. To this end, the VCSEL array comprises at least two subarrays. As used herein, the term "subarray" does not necessarily mean that a subarray comprises multiple VCSELs, but also encompasses situations where a subarray comprises a single VCSEL. Using at least two subarrays, each containing at least one VCSEL, at least two illumination lines can be generated within a target area. Typically, a VCSEL can be considered a quasi-point-like light-emitting element that emits a slightly diverging cone of light. The VCSEL light cone passes through a transmissive optical component, which transforms the light emitted by the subarrays into substantially parallel illumination lines within the target area. Each illumination line has a width along a first axis, along which the subarrays are offset relative to one another. The width of each illumination line is also referred to as its "short dimension," or, for simplicity, the y-direction. Accordingly, in this disclosure, the first axis is also referred to as the y-axis. Each illumination line has a length along a second axis perpendicular to the first axis. The length direction of the illumination line is also referred to as the "long dimension" of the illumination line, and for simplicity, is also referred to as the x-direction. Accordingly, in this disclosure, the second axis is also referred to as the x-axis. Thus, the light emitted by the subarray is transformed in both the y-axis and the x-axis directions. This light transformation preferably results in little or no deformation of the illumination line.

[0012] The total illumination lines generated by the subarrays in combination with the optical components span the entire illumination field, which can be adapted to the field of view of a time-of-flight camera, for example. At least some of the subarrays are individually addressable, meaning they can be driven independently of one another to generate individually addressable illumination lines in a target area. Thus, the light source is adapted to generate one or more subsets of the total illumination lines that the light source is capable of generating. This results in higher peak power in the generated illumination lines and reduces power consumption for signal readout by sensors, such as time-of-flight cameras.

[0013] The optical member is a single optical element, which can be integral or monolithic, and incorporates the ability to transform the light emitted by the subarrays in both the x-axis and the y-axis into an illumination line in the target area. This approach provides a simple, lightweight, and low-cost optical device. The single, integral optical element can be integrated into the VCSEL array chip or can be arranged at a distance from the VCSEL array.

[0014] The illumination lines preferably have a smooth intensity profile in the long dimension (x dimension) and a more or less sharp-edged intensity profile in the short dimension (y dimension). In the case of subarrays each having more than one VCSEL, typically with discrete locations and gaps between adjacent VCSELs, the illumination lines have a smooth intensity profile along their length without dark areas. The length of the illumination lines can be one or more orders of magnitude greater than the width of the illumination lines. For example, the length of each illumination line can be at least 3 times, for example at least 10 times, in particular at least 20 times, or approximately 30 times greater than the width of the illumination line.

[0015] In the following, preferred embodiments of the light source will be described. Preferred embodiments are not only those indicated in the dependent claims but also those indicated in the entire disclosure herein.

[0016] In one embodiment, the optical member may be configured as an imaging lens or a collimating lens in the direction of a first axis, and a diffuser in the direction of a second axis.

[0017] Essentially, the optical member may image or collimate in a first direction (short dimension) while diffusing in a second direction (long dimension).Collimating the light emitted by the sub-array may be advantageous for applications where the target area is spaced, for example, 100 m from the light source.

[0018] Furthermore, the optical components of the light source according to the present invention can have the ability to generate densely packed illumination lines in the target area, i.e., with no or very small gaps in the short dimension between adjacent illumination lines. Densely packed illumination lines can be advantageous because every point in the scene is illuminated by at least one illumination line.

[0019] The optical components of the light source according to the present invention have the capability to smooth or even homogenize the light intensity distribution along the length of the illumination line without significant or even no intensity variations along the length of the illumination line.

[0020] Thus, in one embodiment, the optical component may be configured to generate an illumination line having a uniform light intensity distribution in the direction of the second axis.The light intensity distribution of the illumination line may be uniform in terms of angular intensity or irradiance of the target area.

[0021] In another embodiment, the optical component may be configured to generate an illumination line having a light intensity distribution in the direction of the second axis, wherein the light intensity increases towards ends of the illumination line.

[0022] An illumination line having an increasing intensity distribution or irradiance towards the ends of the illumination line or in other words towards large angles can be advantageous for compensating angle-dependent losses of, for example, a receiver objective of a time-of-flight camera. In an embodiment, the light intensity distribution can be configured according to cos -4 The angle towards the increasing direction increases.

[0023] In one embodiment, the optical component can be configured to generate an illumination line having a substantially top-hat-shaped light intensity distribution in the direction of the first axis. When the illumination line has a top-hat-shaped light intensity distribution, or at least a substantially top-hat-shaped light intensity distribution, in the short dimension, and when the illumination lines are densely arranged with no gaps or no noticeable gaps between adjacent illumination lines, a scene can be illuminated with a uniform light intensity distribution in the Y-axis direction.

[0024] In one embodiment, the optical component may have an optically active surface, wherein the surface shape in a cross-section along a plane containing a first axis and a third axis perpendicular to the first and second axes is aspherical, in particular, having the shape of a conical section. In this embodiment, the imaging or collimating properties of the optical component are imparted by at least one curved, in particular convexly curved, surface of the optical component.

[0025] In the x-axis direction, the optically active surface may also be aspherical, in particular, conical in a cross section containing the second and third axes. In this embodiment, the optical component is a single biconical lens element. The surface shape of the optically active surface in the direction of the first axis may differ from the surface shape in the direction of the second axis in terms of the radius of curvature and / or conic constant and / or aspheric constant.

[0026] The different optical transformation properties described above are tailored to the desired light intensity distribution within each illumination line. The conic constant and / or aspheric constant can be optimized to achieve low distortion of the illumination line and a desired radial intensity profile within the target region. For example, a conic constant of approximately -1 produces uniform irradiance on a flat screen. If the target region is at infinity, the radius of curvature can be adapted to image the light emitted by the subarray onto the scene or to collimate the light emitted by the subarray.

[0027] As an alternative to designing the optical component as a lens with a curved surface, the optical component can be designed as a metalens, which includes a metastructure in the nanoscale range that exhibits a refractive index distribution over its two-dimensional area, which provides the optical component with imaging or collimating properties in the y-direction and diffuser properties in the x-direction.

[0028] In one embodiment, the sub-arrays may be offset relative to each other along the second axis.In this embodiment, the sub-arrays are offset relative to each other along the first axis and along the second axis.

[0029] This embodiment is suitable for obtaining densely packed illumination lines in a target area. As is well known, sub-arrays of VCSELs cannot be packed so densely in the y-direction because some space is required between the individual VCSELs, especially more space is required for electrical contacts, such as bonding pads, solder bumps, etc. By offsetting the sub-arrays along the x-axis, the sub-arrays can be arranged closer to each other in the direction of the first axis, as will be described herein.

[0030] In another embodiment, the optical member may have first facets arranged along a first axis, wherein each first facet of the optical member transforms light emitted from one of the subarrays relative to the first axis. The facets may have curved surfaces with different curvatures, or the facets may be designed as portions of a metalens having different refractive index profiles relative to each other.

[0031] This embodiment also solves the problem of generating aligned illumination lines, even though the subarrays may not be as densely packed on the VCSEL chip. In this embodiment, the subarrays do not need to be moved relative to each other along the second axis. In fact, the first facets can redirect the light emitted by the individual subarrays so that the illumination lines in the target area are arranged close to each other, i.e., side by side with no gaps or only very small gaps. The diameter of each lens facet aperture in the Y direction should be large enough to cover most, preferably the entire, beam emitted by the corresponding subarray.

[0032] Another embodiment may provide for the first facet to be eccentric relative to the sub-array in the direction of the first axis. This embodiment may improve the ability of the optical component to transform the light emitted by the sub-array, so that the generated illumination lines are arranged close to each other, in particular, there are no gaps between adjacent illumination lines in the target area.

[0033] In one embodiment, the optical component may have second facets in the direction of the second axis, wherein the size of each second facet in the direction of the second axis is smaller than, and in particular, much smaller than, the size of the sub-array in the direction of the second axis. Similarly, the second facets may be designed to have curved surfaces or to include facets of a metamaterial.

[0034] In this embodiment, the optical component is faceted in the long dimension of the illumination line. Since the size of the second facet in the long dimension is smaller than the size of the VCSEL subarray in the long dimension, the second facet has a diffusing effect on the light emitted by the subarray in the long dimension. Preferably, the size of the second facet in the long dimension is much smaller than the size of the VCSEL subarray in the long dimension. This ensures that most of the second lens facets are evenly illuminated and that the target profile is evenly distributed in the long dimension. One or more second lens facets can be arranged in front of each subarray in the long dimension. The second facets can be eccentric relative to the VCSEL. In the case where the optical component has first facets arranged along the short dimension, each illumination zone can have multiple second lens facets arranged along the long dimension, and the size of each first facet along the short dimension is large enough to cover the full beam of the corresponding subarray.

[0035] In one embodiment, the optical member may be arranged at a distance from the subarray in the light emission direction that is substantially equal to the focal length of the optical member relative to the first axis and greater than the focal length of the optical member relative to the second axis.

[0036] The focal length of the optical component with respect to light transformation about the second axis (long dimension) may be the focal length of each second facet that the optical component may have according to the above-described embodiments.

[0037] When the optical component is spaced from the subarray by its focal length in the y-direction, it transforms the cone of light emitted by the subarray into a collimated or converging beam. A collimated beam is suitable if the target area is far from the light source, for example, 50 m or even 100 m or more. In this case, the optical component images the light emitted by the subarray to infinity in the short dimension.

[0038] The light source array according to the present invention may include at least five, preferably at least ten, and even more preferably at least twenty sub-arrays. The number of sub-arrays depends on the number of illumination lines to be generated by the light source in the target area. The number of illumination lines depends on the desired area of the illumination field, which in turn may depend on the field of view of the sensor used in conjunction with the light source.

[0039] Each sub-array of the VCSEL array may include at least two VCSELs arranged along the second axis.Each sub-array may include, for example, five or more VCSELs, wherein the VCSELs of each sub-array may be arranged in a row along the second axis.

[0040] According to a second aspect, there is provided a sensor comprising the light source of the first aspect and a detector for detecting light emitted by the light source and reflected or scattered from a target area.

[0041] According to a third aspect, there is provided a method of illuminating a scene, the method comprising:

[0042] providing a light source comprising an array of vertical cavity surface emitting lasers (VCSELs), the array comprising at least two sub-arrays, each sub-array comprising at least one VCSEL, the sub-arrays being offset relative to each other along a first axis, the sub-arrays being configured to individually emit light,

[0043] causing at least one of the subarrays to emit light,

[0044] Light emitted by at least one sub-array is transformed into an illumination line in a target area, the illumination line having a width in a direction of a first axis and a length in a direction of a second axis perpendicular to the first axis, wherein the width is smaller than the length.

[0045] It should be understood that the sensor according to the second aspect and the method according to the third aspect have the same or similar advantages and embodiments as described with respect to the light source according to the first aspect.

[0046] It shall be understood that a preferred embodiment of the invention can also be any combination of the dependent claims with the respective independent claim.

[0047] Further advantages and embodiments are defined below. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the accompanying drawings:

[0049] Figure 1 A schematic diagram showing the principle of a light source for generating an illumination pattern consisting of a plurality of illumination lines;

[0050] Figure 2A shows a front view of an embodiment of a light source for generating an illumination pattern consisting of illumination lines;

[0051] Figure 2B Shown Figure 2A A side view of the light source in FIG.

[0052] Figure 2C Shown Figure 2A and Figure 2B A top view of the light source in FIG;

[0053] Figure 3A shows a front view of another embodiment of a light source for generating an illumination pattern consisting of illumination lines;

[0054] Figure 3B Shown Figure 3A Side view of the middle light source;

[0055] Figure 3C Shown Figure 3A and Figure 3B A top view of the light source in FIG;

[0056] Figure 4 shows the use of Figures 2A to 2C A perspective view of a portion of an embodiment of an optical component used in the illustrated light source;

[0057] Figure 5 Shown Figure 4 A perspective view of a unit cell of an optical component;

[0058] Figure 6 Shown Figure 4 Example diagram of the lens droop profile of the optical component in FIG;

[0059] Figure 7 a simulation showing an illumination pattern composed of illumination lines; and

[0060] Figure 8 A schematic diagram of the sensor is shown. DETAILED DESCRIPTION

[0061] Figure 1 The schematic diagram of the principle of a light source 10 is shown, which generates an illumination pattern 12 composed of a plurality of illumination lines 14 in a target area 16. The target area 16 can be anything, such as a landscape, one or more objects, such as moving objects such as a vehicle, a person, a person making a gesture, etc. The target area 16 can be far away from the light source 10, for example, a few meters to several hundred meters away from the light source 10.

[0062] The light source 10 can be located at the sensor 100 ( Figure 8), for example, for sensing distance, speed, 3D contours of objects or scenery, or for sensing gestures. The sensor 100 may be a time-of-flight camera.

[0063] The light source 10 includes an array 20 of vertical cavity surface emitting lasers (VCSELs) 22 configured to emit light, for example, in the infrared wavelength range.

[0064] The lighting lines 14 of the lighting pattern 12 are substantially parallel to one another. In the illustrated embodiment, the lighting lines 14 are straight. The lighting lines can also be curved, which also includes the lighting lines being parallel because they are concentric. Furthermore, the lighting lines 14 are densely packed, i.e., arranged close together, with very small gaps 18 between adjacent lighting lines 14, or even no gaps at all between adjacent lighting lines 14. The lighting lines 14 can also overlap adjacent lighting lines 14.

[0065] The illumination line 14 is arranged continuously along a first axis, also referred to herein as the y-axis. Along the y-axis, the illumination line 14 has a width, which can be as small as a few millimeters or as large as several centimeters. Along a second axis, also referred to herein as the x-axis, perpendicular to the first axis, the illumination line 14 has a length, which is significantly greater than the width of the illumination line 14. For example, the aspect ratio between the length and width of the illumination line 14 can be greater than 5, such as greater than 10, or approximately 30.

[0066] The light intensity distribution in the illumination line 14 should be smooth in the x-direction, i.e., in the long dimension of the illumination line. In particular, the light intensity distribution in the long dimension may be uniform in angular intensity or irradiance in the target area 16. Alternatively, for example, according to cos 4 The light intensity distribution of the illumination lines 14 in their long dimension may have an increasing irradiance towards large angles, i.e. towards the longitudinal ends of the illumination lines 14. The illumination lines are individually addressable, i.e. one or some illumination lines 14 may be generated at a time while other illumination lines 14 are not generated at the same time.

[0067] In the direction of the y-axis, ie the short dimension of the illumination line 14 , the illumination line 14 may have a more or less sharp-edged, for example top-hat-shaped, light intensity distribution.

[0068] In the following, embodiments of the light source 10 will be described in more detail with reference to further drawings, wherein the same reference numerals denote embodiments and Figure 1 The same, similar or comparable elements.

[0069] Figure 2A A front view of an embodiment of a light source 10 is shown, which includes an array 20 of VCSELs. Figure 2AIn FIG, each VCSEL 22 is represented by a black dot. The array 20 includes two or more sub-arrays 24. Figure 2A In the embodiment shown, as an example, the array 20 includes 15 sub-arrays 24. Each sub-array 24 includes one or more VCSELs 22. In the embodiment shown, as an example, each sub-array 24 includes five VCSELs 22. Although each sub-array 24 is shown to include a row of VCSELs, one or more or all sub-arrays may also include more than one row, for example, two or three rows of VCSELs.

[0070] The subarrays 24 are individually addressable, i.e., the VCSELs 22 of one subarray 24 can be driven to emit light independently of the VCSELs of other subarrays 24. When emitting light, each subarray 24 of VCSELs 22, in combination with optical components 26 described below, is used to produce a line of illumination at a target area.

[0071] In the y-axis direction, the sub-arrays 24 are offset relative to each other. In the x-axis direction, the sub-arrays 24 are also offset relative to each other. This arrangement of the sub-arrays is advantageous if the sub-arrays cannot be densely arranged side by side in the y-axis direction. On the other hand, it is preferable to arrange the illumination lines 14 as densely as possible (e.g., Figure 1 ), so that each point in the target area is illuminated by at least one illumination line, such as Figure 1 Shifting the sub-arrays 24 in the x-direction is one possible way to obtain densely packed illumination lines.

[0072] like Figure 2B and Figure 2C As shown, the light source 10 includes an optical member 26. The optical member 26 is shown as a transmissive optical member in this embodiment. The optical member 26 is a single optical element. All optical functions to be performed by the optical member 26 and described below are thus combined in a single optical element. The light 28 emitted by the VCSEL 22 is transformed by the optical member 26 into an illumination line, such as a Figure 1 The lighting line 14 shown has the same Figure 1 The desired light intensity distribution.

[0073] The optical member 26 may be based on a lighting line, similar to Figure 1 The desired lighting pattern composed of the lighting lines 14 in the image is designed. Figures 2A to 2C In this embodiment, 15 illumination lines can be generated by individually addressing the array 20.

[0074] The design of the optical components may be based on the assumption that a target area such as the target area 16 will be illuminated by N illumination lines, and further based on the assumption that the target illumination field will cover a viewing angle α in the x-axis direction. x (See Figure 1 ) and the viewing angle α in the y-axis direction y (See Figure 1 ) assumption. Angle α x and α y can be defined as the full angle at 50% light intensity. In addition, it can be assumed that the angular width of each illuminated line is determined by α in the y-axis direction. L To describe, when there is no gap between adjacent lighting lines 14, usually α L =α y / N.

[0075] The total height of the array 20 of light sources 10 in the y-axis direction is represented by L y By extending a VCSEL sub-array 24 w y Multiply by the number of zones or lighting lines N. Figure 2A The sub-arrays 24 are shown offset in the x-direction so that despite the large number of illumination lines 14, the overall height of the light source 10 in the y-direction can be kept small.

[0076] Optical component 26 can be a single lens. Optical component 26 is configured to transform the light emitted by VCSEL 22 so as to produce an illumination line with a desired intensity profile in the x-axis and y-axis directions. As described above, the light intensity distribution in the x-axis direction should be smooth, especially uniform, or increase in intensity toward the ends of the illumination line in the x-direction and have more or less sharp edges in the y-axis direction. Optical component 26 is designed to transform the light emitted by each sub-array 24 to a desired width α in a target area, for example, a plane 100 m from light source 10. L .

[0077] The optical component 26 can be configured as an imaging lens or collimating lens in the y-axis direction and a diffuser in the x-axis direction. In the case of a long-distance target area, for example, within a distance of tens of meters or more than 100 meters, collimation is advantageous. The optical component 26 can have at least one optically active surface 28. The optically active surface can be convexly curved to provide the imaging function of the optical component 26 in the y-axis direction, such as Figure 2B The optically effective surface may be an aspherical surface, in particular a conic section in a section including the y-axis and the z-axis. The z-axis is a direction perpendicular to the x-direction and the y-direction and is the direction of light propagation toward the target area 16.

[0078] In other embodiments, the optical member 26 may be a GRIN (gradient index) lens to provide a function of imaging the light emitted by the VCSEL in the y-axis direction to generate an illumination line.

[0079] In yet another embodiment, optical component 26 may be a metalens and, therefore, may be configured as a thin, planar optical element. Metamaterials are structures in the nanometer scale range. These structures provide a refractive index profile that can be adjusted according to a desired optical function, such as imaging or diffusion. The transmittance of the electric and magnetic fields of the metastructure may deviate from the transmittance of a conventional lens. Such a metastructure may include a periodic, microscopic fine structure of electrically or magnetically effective material, wherein the size of such a structure is much smaller than the light emission wavelength of the VCSEL, for example, even less than half the wavelength, such as less than a quarter of the emission wavelength. If optical component 26 includes a metamaterial or a metastructure, optical component 26 does not require a curved surface, but can be a thin, planar, parallel element. Thus, the transformation of light is based on the following principle: the refractive index profile of the metamaterial affects the optical phase, thereby achieving the desired optical transformation of light passing through the metamaterial to produce densely packed illumination lines with little or no distortion.

[0080] In the case of a "conventional" lens as optical member 26, optically active surface 28 can be characterized by its radius of curvature, its conic constant k, and / or its aspheric constant. At least one of these parameters is optimized to achieve low distortion and a desired intensity profile in the target area. For example, the conic constant k can be approximately -1 (for the example of a lens material with a refractive index of 1.5 or close thereto), thereby producing uniform irradiance on a flat panel screen. The radius of curvature can be adapted to image the VCSELs of light source 10 onto a scene or target area, or to collimate the light emitted by the VCSELs if the target area is far away (optically at infinity).

[0081] like Figure 2C As shown, the optically active surface 28 of the optical component 26 is faceted in the x-direction in order to produce an illumination line with a smooth, in particular uniform, intensity distribution.

[0082] Imaging by a single VCSEL 22 in the x-direction is undesirable. Therefore, parameters for the curvature radius and / or the conic constant k and / or the aspheric constant in the x-direction are designed to provide a desired intensity distribution in the x-direction within the target region, for example, for uniform illumination. At least one of the aforementioned parameters of optical component 26 in the x-direction differs from the corresponding parameter in the y-direction.

[0083] exist Figure 2C In FIG. 1 , a portion of the optical element 26 in the x-direction is shown, and a black dot 30 represents a subset 24 in the x-axis direction. The optical element 26 is faceted in the x-axis direction, wherein each lens facet 32 has an aperture size D in the x-axis direction. x smaller than the size w of the subarray 24 in the x-axis direction x .

[0084] According to another method, the optically active surface 28 can be designed in the x-direction by starting with the same curvature radius and conic constant as the optically active surface 28 in the y-direction and assuming D x When uniformly illuminated, the designed lens facet size D x To cover the desired α x Since the subarray size w in the x direction x Possibly related to the required lens size D x The difference is large, so the lens will not be illuminated uniformly. So the lens size D x and the radius of curvature in the x-axis direction can be divided by the same number to make the lens facet size D x Smaller, preferably much smaller than the sub-array size in the x-axis direction. x Dividing by the same number ensures that α x Keep the lens size D x Much smaller than w x It is allowed to arrange several similar (preferably equal) lens facets in the x-axis direction. This ensures that most of the lens facets 32 are illuminated uniformly, and this guarantees a uniform distribution of the target intensity profile.

[0085] In the x-axis direction, one or more lens facets 32 may be arranged in front of each sub-array region (the length of the sub-array 24 in the x-direction) in the x-axis direction. Figure 2C In the embodiment of the present invention, a lens facet 32 is arranged in front of each sub-array region in the x-axis direction. As mentioned above, each region can have multiple rectangular lens facets 32 arranged in the x-axis direction. The lens facets 32 can be eccentric relative to the sub-array region.

[0086] The optical member 26 may be arranged at a distance Z from the array 20 that is equal to the focal length f of the optical member 26 in the y-axis direction. y Relative to the x-axis, the distance Z can be much larger than the focal length f of the lens facet 32 in the x-axis direction. x .

[0087] When the distance between the optical component 26 and the array 20 is Z, α L =w y / f y , and α x With D x / f x Proportional.

[0088] refer to Figures 3A to 3C , another embodiment of the light source 10 will be described. Hereinafter, only Figures 3A to 3C The light source in Figures 2A to 2CThe difference between the light source 10.

[0089] The first difference is that the sub-arrays 24 of the VCSELs 22 of the array 20 are offset relative to each other only in the y-axis direction. In the case of the array 20, the densely packed illumination lines can be generated by the optical member 26 having facets in the y-axis direction (the number of facets is >1, while in Figures 2A to 2C The number of faces of the optical element 26 in the y direction is 1), as shown in FIG. Figure 3B As shown. Thus, the optical member 26 has a plurality of lens facets 36 in the y-axis direction. One lens facet 36 is arranged in front of each zone or sub-array 24 in the y-axis direction. Each lens facet 36 may be eccentric relative to a single sub-array 24. The facets 36 are configured to cause the illumination line 14 ( Figure 1 ) are arranged side by side and preferably close the gaps 18 between the illumination lines 14. Each lens facet may have a size D y , which size is large enough to cover most of the light emitted by the corresponding sub-array 24, preferably to cover the full light beam emitted by the corresponding sub-array 24.

[0090] In the x-axis direction, the optically effective lens surface 28 may be Figure 2C The optical member 26 in is designed in a similar manner. Figure 3C In, w x represents the size of a VCSEL subarray in the x direction, and D x is the lens aperture size of a lens facet 32. Similarly, D x Probably much smaller than w x .

[0091] It should be understood that Figure 3B and Figure 3C The optical transformation functionality of the illustrated optical member 26 can also be achieved by using metamaterials or diffractive optical elements instead of curved surface 28. In the case of a metalens, facets 36 can be parts of the metalens with different refractive index profiles, but the lens itself can have planar surfaces.

[0092] Lens facets 36 of optical member 26 may have different radii of curvature and / or different conic constants and / or aspheric constants.

[0093] Figure 4 Shown Figure 2B and Figure 2C A perspective view of the optical component 26 in FIG. Figure 4As can be seen, optically active surface 28 includes a plurality of lens facets 32 arranged side by side in the x-axis direction. In the y-axis direction, optically active surface 28 is aspherical and can be described as a conic section in the yz plane. In the y-direction, optically active surface 28 can be considered to include a single facet. Optical component 26 includes an overall or global surface profile in the x-direction (excluding lens facets 32). This profile can be curved, for example, aspheric, or particularly conical, in the x-direction, if such curvature is suitable for avoiding distortion in the illumination line. Thus, optical component 26 can be a biconical lens, i.e., conical in both the x- and y-directions. The radius of curvature in the x-direction may differ from the radius of curvature in the y-direction, with the radius of curvature in the y-direction typically being smaller than the radius of curvature in the x-direction. Alternatively or additionally, the conic constant and / or aspheric constant of surface 28 may differ between the x- and y-directions.

[0094] Figure 5 Shown Figure 4 The unit cell 40 of the optical component 26 in FIG. 4 is a single lens facet 32 , wherein the lens facet 32 has an aspherical surface in the y direction, the curvature radius of the aspherical surface being much larger than the surface curvature of the single lens facet 32 in the x direction.

[0095] Figure 6 Shown Figure 4 . Curve 42 represents the lens height profile at the edge of optical member 26, and line 44 represents the lens height profile at the center of the lens. Curve 46 represents curve 42 with its minimum aligned with curve 44, as indicated by arrow 48.

[0096] Figure 7 A simulation diagram of an illumination pattern comprising a total of 40 illumination lines is shown. Thus, the light emissions of the 40 sub-arrays of the VCSEL are imaged as individual illumination lines in the y-axis direction. At the left border of the diagram, the numbers represent the y-coordinate values (in arbitrary units), and the numbers at the bottom of the diagram represent the x-coordinates of the illumination field. The scale on the right side of the diagram represents the (incoherent) irradiance in the illumination field spanned by the illumination lines. In the y-axis direction, the 40 sub-areas are imaged as individually addressable illumination lines, while in the x-axis direction, the optical element (such as optical element 26) acts as a diffuser, adjusting the irradiance in the x-axis direction to be uniform or even slightly increased towards large angles, which may be beneficial for compensating for optical losses in a transceiver system using the light source 10.

[0097] The light source 20 uses Figure 4 The optical element 26 shown obtains Figure 7 A numerical example of the illustrated lighting line pattern may be as follows:

[0098] The viewing angle α in the x direction x =60°; W x =0.64mm (20 VCSELs, 32μm pitch); Figure 4 Optical element 26 in: radius of curvature ROC in the x-direction x =0.006mm; cone constant k in the x direction x = -1; the size of a single facet in the x direction D x =0.02mm; the number of facets in the x direction>=40;

[0099] The viewing angle α in the y direction y =45°; w y =10 μm (each subarray in the y direction has only one VCSEL); 40 subarrays in the y direction, and the center distance of each subarray in the y direction is 10 μm); Figure 4 Optical element 26 in: radius of curvature ROC in the y direction y =0.25mm; cone constant k in the y direction y =-1; D y = 0.7 mm, the number of facets in the y direction = 1 (in this case, D y represents the size of the optically effective surface of the optical element 26).

[0100] exist Figure 7 In the lower half of the diagram shown, only every second lighting line is activated to indicate the intervals of the zones. Figure 7 The rectangular shape of the low-distortion lighting lines in the corners can be clearly seen.

[0101] Figure 8 A sensor 100 is shown, which includes a light source 10 according to any of the above embodiments. The sensor further includes a detector 102 for detecting light emitted by the light source and reflected or scattered from a target area. The detector 102 can be any type of light detecting device, such as a photodiode. The sensor 100 can be integrated into a handheld device (e.g., a smartphone, tablet computer, etc.).

[0102] A method for illuminating a scene can be performed using a light source according to any of the above-described embodiments. The method includes providing a light source according to any of the above-described embodiments. The method also includes causing at least one subarray to emit light. The method also includes transforming the light emitted by the at least one subarray into an illumination line in a target area, the illumination line having a width along a first axis and a length along a second axis perpendicular to the first axis, wherein the width is less than the length. As described above, the light transformation can be performed by optical member 26.

[0103] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention from a study of the drawings, the disclosure, and the appended claims.

[0104] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0105] Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A light source, comprising: An array (20) of vertical cavity surface emitting lasers (VCSELs) (22), the array (20) comprising at least two sub-arrays (24), each sub-array (24) comprising at least one VCSEL (22), the sub-arrays (24) being offset relative to each other along a first axis (y), the sub-arrays (24) being configured to individually emit light independently of light emission from the other sub-arrays (24); and an optical member (26) configured as a single optical element and configured to transform light emitted by the sub-array (24) into substantially parallel illumination lines (14) in a target area (16), wherein the illumination lines are arranged along the first axis (y), each illumination line (14) has a width in the direction of the first axis (y) and a length in the direction of a second axis (x) perpendicular to the first axis (y), the width being smaller than the length, and the optical member (26) has facets (32) in the direction of the second axis (x), wherein a dimension of each facet (32) in the direction of the second axis (x) is smaller than a dimension of the sub-array (24) in the direction of the second axis (x); The optical member (26) is configured as an imaging lens or a collimating lens in the direction of the first axis (y), and a diffuser in the direction of the second axis (x).

2. The light source according to claim 1, wherein The optical component (26) is configured to generate an illumination line (14) having a uniform light intensity distribution in the direction of the second axis (x).

3. The light source according to claim 1, wherein The optical member (26) is configured to generate illumination lines (14) in the direction of the second axis (x), the illumination lines having a light intensity distribution that increases towards the ends of the illumination lines.

4. The light source according to claim 1, wherein The optical member (26) has an optically effective surface (28), wherein the surface shape in a cross section along a plane containing the first axis (y) and a third axis (z) perpendicular to the first axis and the second axis (x, y) is aspherical.

5. The light source according to claim 4, wherein The surface shape is a shape having a conical cross section.

6. The light source according to claim 4, wherein The surface shape of the optically effective surface (28) in the direction of the first axis (y) is different from the surface shape in the direction of the second axis (x) in terms of curvature radius and / or conic constant and / or aspheric constant.

7. The light source according to claim 1, wherein The sub-arrays (24) are offset relative to each other along the second axis.

8. The light source according to claim 1, wherein The optical component (26) has further facets arranged along the direction of the first axis (y), wherein each first facet of the optical component (26) transforms light emitted by one of the sub-arrays (24) relative to the first axis (y).

9. The light source according to claim 8, wherein The further facet is off-centered relative to the sub-array (24) in the direction of the first axis (y).

10. The light source according to claim 1, wherein The optical component (26) is arranged at a distance from the sub-array in the light emission direction, the distance being substantially equal to the focal length of the optical component (26) for light transformation relative to the first axis (y) and greater than the focal length of the optical component (26) for light transformation relative to the second axis (x).

11. The light source according to claim 1, wherein The optical component (26) is a diffractive optical element, a GRIN lens or a super lens.

12. The light source of claim 1, wherein The array (20) includes at least five sub-arrays (24).

13. The light source of claim 12, wherein: The array (20) includes at least ten sub-arrays (24).

14. The light source of claim 13, wherein The array (20) includes at least twenty sub-arrays (24).

15. The light source according to any one of claims 1 to 14, wherein Each sub-array (24) comprises at least two VCSELs (22) arranged along the second axis (x).

16. A sensor comprising the light source (10) according to any one of claims 1 to 15 and a detector (102) for detecting light emitted by the light source (10) and light reflected or scattered from a target area (16).

17. A method of illuminating a scene, comprising: A light source (10) according to any one of claims 1 to 15 is provided such that at least one of the sub-arrays (24) emits light.

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