CROSS REFERENCE TO RELATED APPLICATION

[001] This application is based on and claims benefit of priority of U.S. Provisional Patent Application No. 62/621,066, filed on January 24, 2018, which is incorporated herein by reference in its entirety.

BACKGROUND

[002] There is a growing need to reduce the size of structured light projectors.

SUMMARY

[003] A structured light projector and method for depth measurement is disclosed as illustrated in the specification, drawings and the claims.

[004] In one embodiment, a structured light projector may include a laser array that may include individual light emitters that may be configured to emit light beams; beam control optics; a mask; and projection optics. The beam control optics may be configured to direct the light beams towards a mask area of the mask by changing directions of propagation of at least some of the light beams. The mask may be configured to provide a structured light pattern when illuminated with the light beams. The projection optics may be configured to image the structured light pattern onto an object.

[005] In some embodiments, the mask area may be smaller than an area of the mask illuminated by the light beams absent the beam control optics.

[006] In some embodiments, the beam control optics may include concentration optics for concentrating the light beams towards the mask area. In some embodiments, the light beams may be vertical to the laser array. Further, the beam control optics may be configured to change the directions of propagation of the at least some of the light beams from a vertical to non-vertical directions of propagation. In some embodiments, the beam control optics may be configured to control a divergence of the at least some of the light beams.

[007] In some embodiments, each one of the beam control optics and the mask may be configured to control a divergence of the at least some of the light beams. In some embodiments, each one of the beam control optics and the mask may be configured to increase a divergence of the at least some of the light beams.

[008] In some embodiments, the mask may be configured to increase a divergence of the at least some of the light beams.

[009] In some embodiments, the beam control optics may include a single concentration lens.

[0010] In some embodiments, the beam control optics may include micro-lenses. Each micro-lens may be positioned to receive, a single light beam of the light beams a center of the light beam may be spaced apart from an optical axis of the micro-lens.

[0011] In some embodiments, the beam control optics may include at least one prism.

[0012] In some embodiments, the mask may include at least one backside reflector that may be positioned between at least two openings of the mask. The laser array may include at least one front-side reflector that may be positioned between at least two light emitters of the laser array.

[0013] In some embodiments, the structured light projector may include a radiation flux limiter for limiting a maximal amount of radiation emitted by the projector. [0014] In one embodiment, a structured light projector may include a laser array may include individual light emitters that may be spread across a first area and may be configured to emit light beams;

concentration optics; a mask; and projection optics. The concentration optics may be positioned between the laser array and the mask and may be configured to direct the light beams towards a mask area of the mask by changing directions of propagation of at least some of the light beams. The mask may be configured to provide a structured light pattern when illuminated with the light beams. The projection optics may be configured to image the structured light pattern onto an object.

[0015] In one embodiment, a structured light projector may include a laser array that includes individual light emitters that may be spread across a first area and may be configured to emit light beams; beam control optics that include one or more lenses that may be located within a single imaginary plane; a mask; and projection optics. The beam control optics may be configured to direct the light beams towards a mask area of the mask by changing a direction of propagation of at least some of the light beams. The mask may be configured to provide a structured light pattern when illuminated with the light beams. The projection optics may be configured to image the structured light pattern onto an object.

[0016] In one embodiment, a structured light projector may include a laser array may include individual light emitters that may be spread across a first area and may be configured to emit light beams;

divergence optics; a mask; and projection optics. The divergence optics may be configured to increase a divergence of the light beams and direct the light beams towards the mask. The mask may be configured to provide a structured light pattern when illuminated with the light beams and to increase a divergence of each light beam segment that forms the structured light pattern. The projection optics may be configured to image the structured light pattern onto an object. The divergence optics may solely control the divergence of the light beams. The divergence optics may control additional properties of the light beams. The divergence optics may or may not change the direction of propagation of at least some of the light beams.

[0017] In one embodiment, a depth sensing apparatus may include a structured light projector according to any one of the drawings and/or any example illustrated in the specification. The depth sensing apparatus may also include an imaging sensor configured to generate an image of the object with the structured light pattern projected thereon from a reflected portion of the projected structured light pattern: and a processing unit configured to process the image to determine range parameters. The processing unit may include any hardware processor including but not limited to any integrated chip with processing capabilities, a general-purpose processor, a graphic processor, a digital signals processor and the like.

[0018] In one embodiment, a method is disclosed for projecting a structured light pattern. The method may include emitting light beams by a laser array that may include individual light emitters; directing the beam lights towards a mask area of a mask by changing a direction of propagation of at least some of the light beams; providing, by the mask, the structured light pattern; and imaging, by projection optics, the structured light pattern onto an object.

[0019] In some embodiments, the method may include generating, by an imaging sensor, an image of the object with the structured light pattern projected thereon from a reflected portion of the projected structured light pattern: and processing, by a processing unit, the image to determine range parameters. [0020] In some embodiments, the method may include directing the light beams towards the mask area by beam control optics. In some embodiments, the method may include directing the light beams towards the mask area by concentration optics. In some embodiments, the method may include changing a divergence of the light beams.

[0021] Any method for operating any apparatus and/or any structured light projector illustrated in the drawings and/or the specification is further contemplated.

[0022] The terms“projector” and“structured light projector” are used in an interchangeable manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the drawings:

[0024] Figure 1 is an example of a structured light projector;

[0025] Figure 2 is an example of various components of a structured light projector;

[0026] Figure 3 is an example of projection optics of the structured light projector;

[0027] Figure 4 is an example of various components of a structured light projector;

[0028] Figure 5 is an example of various components of a structured light projector;

[0029] Figure 6 is an example of various components of a structured light projector;

[0030] Figure 7 is an example of a structured light projector;

[0031] Figure 8 is an example of a 3D imaging apparatus that includes a structured light projector; and [0032] Figure 9 is an example of a method.

DETAILED DESCRIPTION

[0033] Any reference to an apparatus or to a structured light projector should be applied, mutatis mutandis to a method that is executed by a 3D imaging apparatus or to a structured light projector.

[0034] Any reference to method should be applied, mutatis mutandis to a 3D imaging apparatus or to a structured light projector that is configured to execute the method. The term“and/or” is additionally or alternatively.

[0035] Consistent with disclosed embodiments, a structured light projector may be used in a three- dimensional (3D) imaging apparatus. The 3D imaging apparatus may include a projector, an imaging sensor and a processor. The projector may include a laser array comprising a plurality of individual laser emitters, beam control optics, a mask for providing a structured light pattern, and projector optics. The structured light pattern may exhibit a non-uniform intensity distribution. See, for example, US Patent Application Publication No. 2016/0191867, published June 30, 2016, which is incorporated herein by reference.

[0036] The laser array may include individual laser emitters that may be configured to emit light beams and the beam control optics may be configured to direct the light beams towards a mask area of the mask by changing a direction of propagation of at least some of the light beams.

[0037] The change in the direction of propagation of at least some of the beams allows for a reduction in the gap between the laser array and the mask and may provide a thinner structured light projector. A thinner structured light projector may be inserted in various devices (such as mobile phones and laptops) that are getting thinner over time. The increment in the divergence increases the overlap between beams, and thus the distance required for providing a given overlap may be decreased.

[0038] When the laser array emits light beams that are orthogonal to the laser array then the changing of the direction of propagation of the at least some of the light beams may define longer optical paths while maintaining the same distance between the mask and the laser array.

[0039] The beam control optics may be configured to concentrate the light beams as well as perform other operations such as controlling the divergence of the light beams. Alternatively, the beam control optics may only concentrate light beams.

[0040] It should be noted that when the beam control optics concentrates the light beams then the projection optics may be simplified and/or be more compact as it is not required to solely concentrate the light beams. For example, non-telecentric projection optics may be used consistent with the disclosed embodiments. Alternatively, the beam control optics may only control the divergence of the light beams even without concentrating the light beams.

[0041] The light beams emitted from the laser array may be too narrow and either one of the mask and the beam control optics may increase the divergence of the light beams. It was found that laser arrays that output light beams having a native divergence of about ten degrees may be associated with sub-optimal numerical aperture values and that a divergence of about twenty-five degrees provides a better numerical aperture, thus achieving increased depth of field and reduced speckle noise for compact optics.

[0042] Figure 1 illustrates an example of a structured light projector 100. The structured light projector 100 may include laser array 1 10, beam control optics 120, mask 130 and projection optics 140. Laser array 1 10 may include individual light emitters that are configured to emit light beams 101. The light emitters of the laser array 1 10 may be substantially non-coherent with one another.

[0043] The light emitters may be vertical cavity surface-emitting lasers ("VCSEL"). By way of non limiting examples, a VCSEL array with an effective emitting area of 2.6 x 2.6 square millimeters can be used. Further by way of example, the VCSEL array can be adapted to produce peak power outputs of approximately 30 watts, when operated in pulsed mode. Each laser in the VCSEL array can be configured to deliver a peak power in the order of 10 milliwatt. For a VCSEL array having about 3000 lasers, the total power can be in the order of about 30 watts.

[0044] It would be appreciated that other types of laser arrays can be used as part of examples of the presently disclosed subject matter, and that a VCSEL is one example of a possible type of laser arrays that may be used. Another example of a laser array that can be used may include an incoherent bundle of lasers coupled optical fibers.

[0045] The laser array 110 may include multiple rows and multiple columns of laser emitters or may have any arrangement of laser emitters. For example, any regular or irregular arrangement may be provided. For example- a rectangular array, a staggered array, a circular array, a triangular shaped array, and the like. Figure 2 illustrates a rectangular grid of N rows and N columns of light sources 1 1 1, e.g., a total of N x N light sources. N being an integer that may exceed and even well exceed 10, 50, 100, 500, 1000 and the like. [0046] Beam control optics 120 may be configured to direct the light beams 101 towards a mask area 131 of mask 130 by changing a direction of propagation of at least some of the light beams. This is illustrated in Figure 1. While light beams 101 exit the laser array having vertical optical axes, parallel to each other, most of light beams 102 that exit the beam control optics are tilted towards the center of the mask 130. The central light beams may not be tilted at all. After passing through mask 130, light beams 103 maintain the tilted direction of light beams 102. Such an embodiment may make use of simplified and/or more compact projection optics 140.

[0047] Mask 130 includes a frame 132 (or other supporting element) that supports a mask area 131 configured to provide a structured light pattern 104 in the far-field when illuminated with light beams 102.

[0048] Mask 130 may include a combination of blocking and transmitting areas, which manipulate the light beams impinging on the mask's surface or passing through the mask 130, such that the light exiting the mask 130 provides a desired structured light pattern. Those versed in the art would appreciate that other types of masks can be used for providing a desired structured light pattern, for example, a holographic type micro lens array, and various types of gratings. The mask 130 may be, for example, a mask that is configured to provide the pattern described in US Patent Application Publication No.

2010/0074532, published March 25, 2010, which is incorporated herein by reference. This mask may be configured to provide an encoded bi-dimensional light pattern that includes a predefined array of a finite set of identifiable feature types. The projected light pattern may take the form of monochromatic light beams of varying intensity, wherein combinations of adjacent light beams comprise encoded features or letters having bi-dimensional spatial formations.

[0049] The beam control optics 120 may be configured to concentrate the light beams that impinge on mask area 131. At the absence of the beam control optics 120, the light beams would impinge an area that is larger than mask area 131.

[0050] Projection optics 140 may be configured to image the structured light pattern onto an object, or onto an object plane 150. By way of example, the projection optics 140 shown in Figure 1 may include (see Figure 3) a pair of lenses 141 and 142.

[0051 ] It would be appreciated that various projection optics are known in the art, including combinations of various types of lenses and other optical elements and can be used in combination with the laser array 110, the beam control optics 120 and the mask 130 according to examples of the presently disclosed subject matter. Different projection optics may be appropriate for different needs and the projection optics can be selected according to a specific need. The parameters of the projection optics that may be tailored in order to fit the projection optics to different needs may include, for example, the actual projection lens used, the desired angular field of view, the desired resolution and depth of field constraints.

[0052] Figure 4 illustrates various examples of the beam control optics 120.

[0053] These examples include (from top to bottom): (a) a single axis lens 121 ; (b) Fresnel lens 122; (c) a micro-lens array 123; and (d) a prism array 124. [0054] Figure 4 also illustrates that the concentration of the light beams may require a change to the direction of propagation of different light beams by different angles. For example, the deflection angle should decrease with a distance to the center of the laser array. Different deflection angles may be obtained by using different optical elements and/or by introducing different spatial relationships between the lasers and the optical elements of the beam control optics.

[0055] The deflection may be achieved by off-axis illumination by illuminating micro-lenses with light beams that have their center outside of the optical axis of the micro-lens. For a given micro-lens, different deflection angles may be obtained when introducing different distances between the optical axis of the given micro-lens and the center of an impinging light beam.

[0056] For example, a first light beam from first laser emitter 1 10(a) may impinge on first micro-lens 123(a). There is a first distance D1 between the center of first light beam and the optical axis OA1 of first micro-lens 123(a). Second light beam from second laser emitter 1 10(b) impinges on second micro-lens 123(b). There is a second distance D2 between the center of second light beam and the optical axis OA2 of second micro-lens 123(b). D1 is smaller than D2 and the first light beam is less deflected than the second light beam.

[0057] As another example, first light beam from first laser emitter 110(a) may impinge on first prism 124(a). Second light beam from second laser emitter 110(b) may impinge on second prism 124(b). Slope angle SA1 of first prism 124(a) is smaller than Slope angle SA2 of second prism 124(b). Accordingly, the first light beam is less deflected than the second light beam.

[0058] The beam control optics may include any combination of optical elements for changing the direction of propagation of light beams and/or for controlling the divergence of the light beams.

[0059] According to an embodiment, the beam control optics may be thin. For example, the beam control optics may be positioned within a single plane may include a single array of micro-lenses and/or may include other optical elements.

[0060] It should be noted that the beam control optics and/or the mask may control the divergence of the light beams, especially may increase or decrease the divergence of the light beam, thereby expanding or narrowing the light beams.

[0061] Figure 5 illustrates first micro-lens 123(a) and mask 130 as expanding a light beam emitted by laser emitter 110(a). In this example, the exit divergence 502 is larger than the input divergence 501. In some embodiments, only one of the first lens 123(a) and the mask 130 may expand the light beam.

Further, in some embodiments, due to diffraction, mask 130 may only expand the light beam, but may not narrow the light beam.

[0062] Figure 6 illustrates how mask 130 and the laser array 1 10 may perform light recycling by reflecting light between reflecting elements 134 of the mask and reflecting elements 1 14 of the laser array in order to allow initially blocked light to eventually pass through one or more of the openings of the mask. The reflecting elements of the laser array may be positioned between light emitters. The reflecting elements 114 and reflecting elements 134 may be of any shape and/or size and can be made of reflecting materials such as aluminum, chrome, gold, silver and the like. The reflecting elements and/or any part of the mask may be manufactured by any process known in the art- such as coating, etching, and the like.

[0063] The mask 130 may include a backside reflector that may include one or more reflecting elements 134 that are positioned between at least two openings of mask area 131. The laser array may include at least one front-side reflector that is positioned between at least two light emitters of the laser array.

[0064] For safety reasons (or for any other appropriate reason) there may be a need to reduce the maximal amount of radiation that is outputted by the structured light projector 100. Figure 7 illustrates a radiation flux limiter 170 for limiting the maximal amount of radiation emitted. The radiation flux limiter may form a fixed aperture of any shape - circular, polygon-shaped, or any other shape. The radiation flux limiter may be positioned downstream of the projection optics, between different lenses of the projection optics, or elsewhere.

[0065] According to an aspect of the examples of the presently disclosed subject matter, a 3D imaging apparatus can be provided, which includes a projector for 3D range finding according to the examples of the subject matter that were described above.

[0066] Figure 8 is a block diagram illustration of a 3D imaging apparatus, according to examples of the presently disclosed subject matter.

[0067] According to examples of the presently disclosed subject matter, the 3D imaging apparatus 800 can include an imaging sensor 820, a processing unit 830 and projector 810.

[0068] The projector 810 can be implemented in accordance with the examples of the projector described hereinabove, including but not limited to with reference to Figures 1 -7.

[0069] The imaging sensor 820 can be adapted to capture an image of the object with the structured light pattern projected thereon. There is a variety of imaging sensors which can be used for capturing an image of the object with the structured light pattern projected thereon and to provide an image that is suitable for 3D range finding applications. Any suitable imaging sensor that is currently available or that will be available in the future can be used for capturing an image of the object with the structured light pattern projected thereon.

[0070] According to examples of the presently disclosed subject matter, the imaging sensor 820 can be positioned relative to the projector 810 in a manner to provide a specific imaging geometry that is appropriate for 3D range finding applications. In further examples of the presently disclosed subject matter, the imaging sensor can be operatively connected to the projector 810 and the operation of the imaging sensor 820 and of the projector 810 can be synchronized, for example, in order to achieve better power efficiency for the 3D imaging apparatus 800.

[0071] According to examples of the presently disclosed subject matter, the processing unit 830 can be adapted to process an image that was captured by the imaging sensor 820 and can provide range parameters. Various algorithms which can be used to extract range parameters from an image of an object having projected thereupon a pattern can be implemented by the processing unit 830.

[0072] Figure 9 illustrates a method 200, Method 200 may include steps 210, 220, 230, 240, 250, and 260. Method 200 may include projecting a structured light pattern. [0073] Step 210 may include emitting light beams by a laser array that includes individual light emitters. Step 220 may include directing the beam lights towards a mask area of a mask by changing a direction of propagation of at least some of the light beams. The directing may be executed by beam control optics, beam divergence optics and/or beam concentration optics.

[0074] Step 230 may include providing, by the mask, a structured light pattern. Step 240 may include casting, by projection optics, the structured light pattern onto an object.

[0075] Method 200 may also include light recycling, such as by reflecting light beams between the mask and the laser array until the light beams pass through the mask.

[0076] Step 250 may include generating, by an imaging sensor, an image of the object with the structured light pattern projected thereon from a reflected portion of the projected structured light pattern. Step 260 may include processing, by a processing unit, the image to determine range parameters. The range parameters may include ranges of different pixels in the image.

[0077] Method 200 may be used for 3D face recognition or for any other purpose. The range parameters may be compared to signatures obtained by illuminating various people with the structured light pattern.

[0078] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0079] Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions various functional terms refer to the action and/or processes of a computer or computing device, or similar electronic computing device, that manipulate and/or transform data represented as physical, such as electronic, quantities within the computing device's registers and/or memories into other data similarly represented as physical quantities within the computing device's memories, registers or other such tangible information storage, transmission or display devices.

[0080] In the foregoing specification, specific examples of embodiments have been described. It will, however, be evident that various modifications and changes may be made therein without departing from the broader spirit and scope of the disclosed embodiments as set forth in the appended claims.

[0081] Moreover, the terms“front,”“back,”“top,”“bottom,”“over,� ��“under” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the disclosed embodiments described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[0082] Any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermediate components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality.

[0083] Furthermore, those skilled in the art will recognize that boundaries between the above described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

[0084] However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[0085] The phrase“may be X” indicates that condition X may be fulfilled. This phrase also suggests that condition X may not be fulfilled. For example, any reference to a method as including a certain step should also cover the scenario in which the method does not include the certain component.

[0086] The terms "including," "comprising," "having," "consisting," and "consisting essentially of' are used in an interchangeable manner.

[0087] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0088] Moreover, the terms "front, " "back, " "top, " "bottom, " "over, " "under " and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[0089] Those skilled in the art will recognize that the boundaries between logic blocks are merely illustrative and that alternative embodiments may merge logic blocks or circuit elements or impose an alternate decomposition of functionality upon various logic blocks or circuit elements. Thus, it is to be understood that the architectures depicted herein are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality.

[0090] Any arrangement of components to achieve the same functionality is effectively "associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermediate components. Likewise, any two components so associated can also be viewed as being "operably connected,” or "operably coupled,” to each other to achieve the desired functionality.

[0091] Furthermore, those skilled in the art will recognize that boundaries between the above described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments.

[0092] Also, for example, in one embodiment, the illustrated examples may be implemented as circuitry located on a single integrated circuit or within a same device. Alternatively, the examples may be implemented as any number of separate integrated circuits or separate devices interconnected with each other in a suitable manner.

[0093] Also, for example, the examples, or portions thereof, may implemented as software or code representations of physical circuitry or of logical representations convertible into physical circuitry, such as in a hardware description language of any appropriate type.

[0094] Also, the disclosed embodiments are not limited to physical devices or units implemented in nonprogrammable hardware but can also be applied in programmable devices or units able to perform the desired device functions by operating in accordance with suitable program code, such as mainframes, minicomputers, servers, workstations, personal computers, notepads, personal digital assistants, electronic games, automotive and other embedded systems, cell phones and various other wireless devices, commonly denoted in this application as computer systems.

[0095] However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[0096] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms "a” or "an,” as used herein, are defined as one as or more than one. Also, the use of introductory phrases such as "at least one " and "one or more " in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a " or "an " limits any particular claim containing such introduced claim element containing only one such element, even when the same claim includes the introductory phrases "one or more " or "at least one " and indefinite articles such as "a " or "an. " The same holds true for the use of definite articles. Unless stated otherwise, terms such as "first” and "second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements the mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[0097] Any system, apparatus or device referred to this patent application may include at least one hardware component.

[0098] While certain features of the disclosed embodiments have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosed embodiments.