Patent Publication Number: US-2023133647-A1

Title: Non-zero angle orientation of an emitter array relative to a rectilinear axis of a submount

Description:
RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 63/263,201, filed on Oct. 28, 2021, and entitled “DOT PROJECTOR PATTERN RANDOMNESS BY INTRODUCING A ROTATION ANGLE RELATIVE TO CAMERA AXES,” the content of which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a structured light system and to a dot projection module of the structured light system. 
     BACKGROUND 
     A structured light system may include an emitter array (e.g., a vertical-cavity surface-emitting laser (VCSEL) array), a lens, and a diffractive optical element (DOE). In operation, light emitted by emitters of the emitter array is collimated by the lens, and beams of collimated light (each corresponding to a respective emitter) are directed to the DOE. The DOE distributes the collimated beams of light in order to create a dot projection (e.g., a projection of the collimated beams). More specifically, the DOE diffracts a given beam of light such that diffracted orders of the given beam are transmitted by the DOE at different angles. An angular extent of the diffraction occurs over a range of angles relative to a surface of the DOE referred to as a field of view (FOV). The FOV can be, for example, a 60 degree FOV, a 90 degree FOV, or the like. These differently directed diffracted orders form a dot projection (e.g., that includes thousands or tens of thousands of spots) in the FOV. 
     SUMMARY 
     In some implementations, a structured light system includes a camera module; and a dot projection module that includes: a submount, an emitter array disposed on the submount, and a diffractive optical element (DOE) disposed over the emitter array, wherein: the emitter array includes a plurality of emitters arranged in a periodic emitter pattern, and the emitter array is oriented at a first non-zero angle relative to a rectilinear axis of the submount. 
     In some implementations, a dot projection module includes a submount; and an emitter array disposed on the submount, wherein: the emitter array includes a plurality of emitters arranged in a periodic emitter pattern, and the emitter array is oriented at a first non-zero angle relative to a rectilinear axis of the submount. 
     In some implementations, a structured light system includes a camera module; and a dot projection module configured to generate a dot projection, wherein: the dot projection includes a plurality of dots that corresponds to a periodic emitter pattern of a plurality of emitters of an emitter array of the dot projection module; and the dot projection is oriented at a first non-zero angle relative to a rectilinear axis of a field of view of the camera module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram of an example structured light device described herein. 
         FIG.  2    is a diagram of an example configuration of a dot projection module described herein. 
         FIG.  3    is a diagram of an example configuration of a dot projection herein. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of example implementations refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
     A three-dimensional (3D) sensing time of flight (ToF) device, such as a ToF camera, may include an emitter array (e.g., a vertical-cavity surface-emitting laser (VCSEL) array), a lens, and a diffractive optical element (DOE). In operation, light emitted by emitters of the emitter array (e.g., infrared (IR) light) is collimated by the lens, and beams of collimated light (each corresponding to a respective emitter) are directed to the optical element. The optical element distributes the collimated beams of light to create a dot projection (e.g., a projection of the collimated beams) on a subject. More specifically, the optical element diffracts a given beam of light such that diffracted orders of the given beam are transmitted at different angles. The 3D sensing ToF device may include one or more additional elements (e.g., one or more sensors and/or processors) to sense the dot projection and make one or more measurements concerning the subject based on the dot projection. 
     In many cases, non-uniformity of dots of the dot projection in x and y directions of a field of view (FOV) of a ToF camera facilitates the one or more additional elements in obtaining accurate measurements concerning the subject. For example, a spacing between dots and/or a placement of a dots along (or parallel to) an axis of the FOV of the ToF camera should be non-uniform. Typically, this is achieved by randomizing locations of emitters within the emitter array. However, to obtain a particular dot count, an optical element (e.g., a DOE and/or a diffuser) is required to generate multiple high order tiles of a zero-order pattern (e.g., a projection of dots associated with the emitter array when no DOE and/or diffuser is present). Repeat tiling of the zero-order pattern reduces a non-uniformity of an overall dot pattern of the dot projection as the zero-order pattern is repeated multiple times along x and y axes of the FOV of the ToF camera. In some cases, the tiles may be shifted to increase a non-uniformity of the overall dot pattern, but only in one direction (e.g., along a particular axis and not along another axis). 
     Some implementations described herein provide a structured light system that includes a camera module and a dot projection module. The dot projection module includes a submount, an emitter array disposed on the submount, a lens disposed over the emitter array, and a DOE disposed over the lens and the emitter array. The emitter array includes a plurality of emitters arranged in a periodic emitter pattern (e.g., a two-dimensional periodic pattern) and the emitter array is oriented at a non-zero angle relative to a rectilinear axis of the submount. Accordingly, the dot projection module generates a dot projection (e.g., from light emitted by the plurality of emitters of the emitter array). The dot projection comprises a plurality of tiles, wherein each tile comprises a plurality of dots that conform to a periodic dot pattern that corresponds to the periodic emitter pattern (e.g., each dot of the periodic dot pattern is associated with an emitter of the emitter pattern). In some implementations, the dot projection  116  is oriented at a non-zero angle relative to one or more rectilinear axes of an FOV of the camera module. 
     In this way, some implementations described herein increase a non-uniformity of a dot projection in x and y directions of the FOV of the camera module. Accordingly, the dot projection is more heterogeneous in x and y directions of the FOV of the camera module than that produced using a conventional emitter array (e.g., that does not have a non-zero angle orientation), which allows the camera module to obtain a more accurate measurement of a subject illuminated by the dot projection. 
       FIG.  1    is a diagram of an example structured light device  100  described herein. As shown in  FIG.  1   , a structured light device  100  may include a dot projection module  102 . The dot projection module  102 , may include, for example, a submount  104 , an emitter array  106  that includes a plurality of emitters  108  (e.g., arranged in an emitter pattern  110 ), a lens  112 , and/or an optical element  114 . 
     The plurality of emitters  108  of the emitter array  106  may be configured to emit light and may include, for example, a plurality of light emitting diodes (LEDs), a plurality of vertical-cavity surface-emitting lasers (VCSELs), a plurality of other types of vertical emitting (e.g., top emitting or bottom emitting) laser devices, and/or other types of light emitting devices. The plurality of emitters  108  may be arranged in the emitter pattern  110  (e.g., in a surface of a chip of the emitter array  106 ), which is further described herein in relation to  FIG.  2   . 
     The submount  104  may include a structure to hold the emitter array  106  (e.g., within an internal portion of the dot projection module  102 ). The submount  104  may include, for example, a structure (e.g., that comprises a metal material, a dielectric material, a semiconductor material, or another material) that is configured to attach to the chip of the emitter array  106 . The chip of the emitter array  106  may include, for example, a polymer dielectric material, such as FR 4  (e.g., a flame resistant or self-extinguishing composite material made from woven fiberglass cloth with an epoxy resin binder), a ceramic material (e.g., a high temperature co-fired ceramic (HTCC) material or a low temperature co-fired ceramic (LTCC) material), a semiconductor material (e.g., that includes gallium arsenide (GaAs), indium phosphide (InP), and/or germanium (Ge)), or another material. As shown in  FIG.  1   , and as further described herein in relation to  FIG.  2   , the emitter array  106  may be disposed on the submount  104  and may be oriented at a non-zero angle relative to a rectilinear axis of the submount  104 . 
     The lens  112  may include a glass lens, a polymer lens, or another lens and may be configured to collimate light (e.g., that was emitted by the plurality of emitters  108 ) and/or direct the light to the optical element  114 . The optical element  114  may include a diffractive optical element (DOE), a diffuser, and/or a similar optical element and may be configured to diffract light (e.g., that was emitted by the plurality of emitters  108  and/or directed to the optical element  114  by the lens  112 ). The lens  112  may be disposed over the emitter array  106  and the optical element  114  may be disposed over the emitter array  106  and/or the emitter array  106 . For example, as shown in  FIG.  1   , the optical element  114 , the lens  112 , and the emitter array  106  may be aligned in a “stack” (e.g., where the optical element  114 , the lens  112 , and the emitter array  106  are aligned with a reference line, such as an optical axis of the lens  112 ). 
     In some implementations, the dot projection module  102  may be configured to generate a dot projection  116  (e.g., from light emitted by the plurality of emitters  108  of the emitter array  106 ). For example, the plurality of emitters  108  of the emitter array  106  may be configured to emit light, the lens  112  may be configured to collimate the light and/or direct the light to the optical element  114 , and the optical element  114  may be configured to generate the dot projection  116  across a scene (e.g., that includes a target and/or an object). The dot projection  116  may comprise a plurality of tiles, wherein each tile comprises a plurality of dots that conform to a dot pattern that corresponds to the emitter pattern  110  (e.g., each dot of the dot pattern is associated with an emitter  108  of the emitter pattern  110 ). The dot projection  116  is further described herein in relation to  FIG.  3   . 
     In some implementations, the structured light device  100  may include a camera module  118 . The camera module  118  may be configured to detect reflected light  120  (e.g., light of the dot projection  116  that is reflected by the scene to the camera module  118 ). The camera module  118  may include a lens  122  and/or an optical sensor  124 . The lens  122  may include a glass lens, a polymer lens, or another lens and may be configured to focus light (e.g., the reflected light  120 ) and/or direct the light to the optical sensor  124 . The optical sensor  124  may include a plurality of sensor elements  126 . A sensor element  126  may be configured to obtain information regarding a light beam (e.g., of the reflected light) that falls incident on the sensor element  126  (e.g., after being focused and/or directed by the lens  122 ). Accordingly, the optical sensor  124  may be configured to collect information obtained by the plurality of sensor elements  126  to generate sensor data associated with the scene (e.g., to measure the target and/or the object). 
     The lens  122  may be disposed over the optical sensor  124 . For example, the lens  122  and the optical sensor  124  may be aligned in a “stack” (e.g., where the lens  122  and the optical sensor  124  are aligned with a reference line, such as an optical axis of the lens  122 ). 
     As indicated above,  FIG.  1    is provided as an example. Other examples may differ from what is described with regard to  FIG.  1   . 
       FIG.  2    is a diagram  200  of an example configuration of the dot projection module  102  described herein. As shown in  FIG.  2   , the dot projection module  102  may include the submount  104 , the emitter array  106  that includes the plurality of emitters  108 , the lens  112 , and/or the optical element  114  (e.g., as described herein in relation to  FIG.  1   ). 
     As further shown in  FIG.  2   , the emitter array  106  may be arranged in the emitter pattern  110 . In some implementations, the emitter pattern  110  may be a periodic emitter pattern, such as an oblique two-dimensional emitter pattern, a rectangular two-dimensional emitter pattern, a centered rectangular two-dimensional emitter pattern, a square two-dimensional emitter pattern, a hexagonal two-dimensional emitter pattern, and/or another periodic two-dimensional emitter pattern. Accordingly, in some implementations, the emitter pattern  110  may correspond to a monoclinic two-dimensional Bravais lattice, an orthorhombic two-dimensional Bravais lattice, a tetragonal two-dimensional Bravais lattice, and/or a hexagonal two-dimensional Bravais lattice. 
     As further shown in  FIG.  2   , the emitter pattern  110  may be aligned with one or more rectilinear axes (shown in  FIG.  2    as an x-axis and a y-axis) of the emitter array  106  (e.g., of the chip of the emitter array  106 ). Accordingly, the emitter pattern  110  may have an emitter pitch D 1  in an x-direction of the emitter array  106  (e.g., a distance D 1  between adjacent emitters  108  in the x-direction of the emitter array  106 ) and/or an emitter pitch D 2  in a y-direction of the emitter array  106  (e.g., a distance D 2  between adjacent emitters  108  in the y-direction of the emitter array  106 ). In some implementations, the emitter pitch D 1  in the x-direction of the emitter array  106  may match the emitter pitch D 2  in the y-direction of the emitter array  106  (e.g., the emitter pitch D 1  in the x-direction of the emitter array  106  is equal to the emitter pitch D 2  in the y-direction of the emitter array  106  within a tolerance, which may be less than or equal to  10  nanometers (nm)), or, alternatively, the emitter pitch D 1  in the x-direction of the emitter array  106  may differ from the emitter pitch D 2  in the y-direction of the emitter array  106  (e.g., a difference between the emitter pitch D 1  in the x-direction of the emitter array  106  the emitter pitch D 2  in the y-direction of the emitter array  106  is greater than 10 nm). 
     As further shown in  FIG.  2   , the emitter array  106  (e.g., the chip of the emitter array  106 ) may be oriented at a non-zero angle relative to one or more rectilinear axes of the submount  104  (shown in  FIG.  2    as an x-axis and a y-axis). For example, as shown in  FIG.  2   , the emitter array  106  may be oriented at a non-zero angle αi relative to the x-axis of the submount  104  and may be oriented at a non-zero angle α 2  relative to the y-axis of the submount  104 . When the emitter array  106  has a rectangular shape (e.g., the emitter array  106  has four sides, such as with internal right angles, as shown in  FIG.  2   ), the non-zero angle α 1  may match (e.g., be equal to within a tolerance, which may be less than or equal to 1 degree) the non-zero angle α 2 . Each of the non-zero angle α 1  and the non-zero angle α 2  may be between 2 degrees and 30 degrees (e.g., greater than or equal to 2 degrees and less than or equal to 30 degrees). In some implementations, when the emitter pattern  110  is aligned with one or more rectilinear axes of the emitter array  106 , the plurality of emitters  108  and/or the emitter pattern  110  may be oriented at a non-zero angle relative to one or more rectilinear axes of the submount  104 . For example, the plurality of emitters  108  and/or the emitter pattern  110  may be oriented at the non-zero angle α 1  relative to the x-axis of the submount  104  and may be oriented at the non-zero angle α 2  relative to the y-axis of the submount  104 . 
     Additionally, or alternatively, the optical element  114  may be oriented at a non-zero angle relative to the one or more rectilinear axes of the submount  104 . For example, when the optical element  114  has a rectangular shape (e.g., the optical element  114  has four sides, such as with internal right angles), one or more rectilinear axes of the optical element  114  may be respectively aligned with one or more rectilinear axes of the emitter array  106  (e.g., the optical element  114  may be oriented at an approximately zero angle relative to the one or more rectilinear axes of the emitter array  106 , such as zero degrees within a tolerance, which may be less than or equal to 1 degree). Accordingly, the optical element  114  may be oriented at a same non-zero angle relative to the one or more rectilinear axes of the submount  104  as that of the emitter array  106 . 
     As indicated above,  FIG.  2    is provided as an example. Other examples may differ from what is described with regard to  FIG.  2   . 
       FIG.  3    is a diagram  300  of an example configuration of the dot projection  116  described herein. The dot projection  116  may be generated by the dot projection module  102  from light emitted by the plurality of emitters  108  of the emitter array  106  (e.g., as described elsewhere herein). 
     As shown in  FIG.  3   , the dot projection  116  may include a plurality of dots  302 . The plurality of dots  302  may correspond to the emitter pattern  110  of the plurality of emitters  108  of the emitter array  106  of the dot projection module  102  (e.g., as described herein in relation to  FIGS.  1  and  2   ). For example, the dot projection  116  may comprise a plurality of tiles  304  (e.g., arranged in a two-dimensional array of tiles), wherein each tile  304  may include a subset of dots  302  of the plurality of dots  302 . The subset of dots  302  may conform to a dot pattern  306  that corresponds to the emitter pattern  110  of the plurality of emitters  108  of the emitter array  106  (e.g., each dot  302  of the dot pattern  306  is associated with an emitter  108  of the emitter pattern  110 ). For example, a tile  304  may be an optical projection of the emitter pattern  110 , and, accordingly, the dot pattern  306  (e.g., as shown in  FIG.  3   ) may include a same number and arrangement of dots  302  as that of the plurality of emitters  108  of the emitter pattern  110  (e.g., as shown in  FIGS.  1  and  2   ). In this way, the dot pattern  306  may be a periodic dot pattern, such as an oblique two-dimensional dot pattern, a rectangular two-dimensional dot pattern, a centered rectangular two-dimensional dot pattern, a square two-dimensional dot pattern, a hexagonal two-dimensional dot pattern, and/or another periodic two-dimensional dot pattern. Accordingly, in some implementations, the dot pattern  306  may correspond to a monoclinic two-dimensional Bravais lattice, an orthorhombic two-dimensional Bravais lattice, a tetragonal two-dimensional Bravais lattice, and/or a hexagonal two-dimensional Bravais lattice. 
     In some implementations, the dot projection  116  may have one or more rectilinear axes. For example, when the dot projection  116  has a rectangular shape (e.g., the dot projection  116  has four sides, such as with internal right angles, as shown in  FIG.  3   ), the dot projection  116  may include a dot projection x-axis  308  and a dot projection y-axis  310 . Accordingly, the plurality of dots  302  and/or the plurality of tiles  304  may be aligned with the one or more rectilinear axes of the dot projection  116 . Moreover, each dot pattern  306  of the plurality of tiles  304  may be aligned with the one or more rectilinear axes of the dot projection  116 . 
     As further shown in  FIG.  3   , the dot projection  116  may be at least partially coextensive with a field of view (FOV)  312  of the camera module  118  (e.g., a FOV of detection of the camera module  118 ). The camera module FOV  312  may have one or more rectilinear axes. For example, when the camera module FOV  312  has a rectangular shape (e.g., the camera module FOV  312  has four sides, such as with internal right angles, as shown in  FIG.  3   ), the camera module FOV  312  may include a camera module FOV x-axis  314  and a camera module FOV y-axis  316 . 
     In some implementations, the dot projection  116  may be oriented at a non-zero angle relative to one or more rectilinear axes of the camera module FOV  312  (shown in  FIG.  3    as an x-axis and a y-axis). For example, as shown in  FIG.  3   , the dot projection  116  may be oriented at a non-zero angle β 1  relative to the camera module FOV x-axis  314  and may be oriented at a non-zero angle β 2  relative to camera module FOV y-axis  316 . When the dot projection  116  has a rectangular shape (e.g., the dot projection  116  has four sides, such as with internal right angles, as shown in  FIG.  3   ), the non-zero angle β 1  may match the non-zero angle β 2  (e.g., be equal to within a tolerance, which may be less than or equal to 1 degree). Each of the non-zero angle β 1  and the non-zero angle β 2  may be between 2 degrees and 30 degrees (e.g., greater than or equal to 2 degrees and less than or equal to 30 degrees). In some implementations (e.g., when the plurality of dots  302 , the plurality of tiles  304 , and/or the dot pattern  306  of each tile  304  are aligned with one or more rectilinear axes of the dot projection  116 ), the plurality of dots  302 , the plurality of tiles  304 , and/or the dot pattern  306  of each tile  304  may be oriented at a non-zero angle relative to one or more rectilinear axes of the camera module FOV  312 . For example, the plurality of dots  302 , the plurality of tiles  304 , and/or the dot pattern  306  of each tile  304  may be oriented at the non-zero angle β 1  relative to the camera module FOV x-axis  314  and may be oriented at the non-zero angle β 2  relative to camera module FOV y-axis  316 . 
     In some implementations, the non-zero angle of the dot projection  116  may match (e.g., be equal to within a tolerance, which may be less than or equal to 1 degree) the non-zero angle of the emitter array  106 . For example, the non-zero angle β 1  may be equal to the non-zero angle α 1  and/or the non-zero angle β 2  may be equal to the non-zero angle α 2 . Accordingly, any two (or more) of the respective non-zero angles of the emitter array  106 , the plurality of emitters  108 , the emitter pattern  110 , the optical element  114 , the dot projection  116 , the plurality of dots  302 , the plurality of tiles  304 , and/or the dot pattern  306  of each tile  304 , may match (e.g., be equal to within a tolerance, which may be less than or equal to 1 degree) each other. 
     As indicated above,  FIG.  3    is provided as an example. Other examples may differ from what is described with regard to  FIG.  3   . 
     The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the implementations. Furthermore, any of the implementations described herein may be combined unless the foregoing disclosure expressly provides a reason that one or more implementations may not be combined. 
     Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set. As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiple of the same item. 
     No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Further, as used herein, the article “the” is intended to include one or more items referenced in connection with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items), and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Also, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and/or,” unless explicitly stated otherwise (e.g., if used in combination with “either” or “only one of”). Further, spatially relative terms, such as “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the apparatus, device, and/or element in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.