Diffractive optical element with collimator function

Abstract

An example distance sensor includes a light projection system for projecting a pattern of points of light onto an object. The light projection system includes a laser light source for projecting coherent light and a diffractive optical element having a plurality of layers etched to form a binary step pattern, where the plurality of layers are configured to split the coherent light into a plurality of light beams, where each light beam forms one point of the pattern, and where the plurality of layers are further configured to control a divergence angle of the light beams. The example distance sensor also includes a light receiving system for capturing an image of the pattern projected onto the object, and a processor for calculating a distance to the object based on an appearance of the pattern in the image and knowledge of a trajectory of the light points.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 013,002, filed April 21, 2020, which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention generally relates to distance measurement, and more specifically to distance sensors comprising diffractive optical elements having collimator functionality. Background Technology

[0004] Many technologies, including those for autonomous navigation, robotics, and other applications, rely on measurements of three-dimensional maps of the surrounding space to aid in collision avoidance, route confirmation, and other tasks. For example, a three-dimensional map can indicate the distances to various objects in the surrounding space.

[0005] In some examples, a sensor used to measure distance can project a pattern of light (e.g., infrared light) onto the surface of an object whose distance is being measured. The light pattern can include multiple discrete points of light, each created when a single beam of light emitted from the distance sensor is incident on the object's surface. The distance to the object can then be calculated based on the appearance of the pattern. In some examples, the multiple beams used to create the pattern are created by splitting a single coherent beam emitted by the distance sensor's light projection system into multiple beams using diffractive optics. Summary of the Invention

[0006] An exemplary distance sensor includes a light projection system for projecting a pattern comprising a plurality of light spots onto an object. The light projection system includes a laser source for projecting coherent light and diffractive optical elements having multiple layers etched to form a binary stepped pattern, wherein the multiple layers are configured to split the coherent light into multiple beams, wherein each of the multiple beams forms a point among the plurality of light spots, and wherein the multiple layers are further configured to control the divergence angle of the multiple beams. The exemplary distance sensor also includes a light receiving system for capturing an image of the pattern projected onto the object and a processor for calculating the distance to the object based on the appearance of the pattern in the image and knowledge of the trajectories of the multiple light spots.

[0007] In one example, a method performed by a processing system of a distance sensor comprising at least one processor includes causing a light projection system of the distance sensor to project a pattern onto an object, wherein the pattern comprises a plurality of light points, and wherein the plurality of light points are formed by a diffractive optical element of the light projection system comprising a collimator function; causing a light receiving system of the distance sensor to capture an image of the pattern projected onto the object; and, computing a set of three-dimensional coordinates for at least some of the plurality of light points, wherein the computing is based on knowledge of an appearance of the at least some points in the image and a trajectory of the at least some points.

[0008] In another example, a non-transitory machine-readable storage medium is encoded with instructions executable by a processing system of a distance sensor comprising at least one processor. When executed, the instructions cause the processing system to perform operations including causing a light projection system of the distance sensor to project a pattern onto an object, wherein the pattern comprises a plurality of light points, and wherein the plurality of light points are formed by a diffractive optical element of the light projection system comprising a collimator function; causing a light receiving system of the distance sensor to capture an image of the pattern projected onto the object; and, computing a set of three-dimensional coordinates for at least some of the plurality of light points, wherein the computing is based on knowledge of an appearance of the at least some points in the image and a trajectory of the at least some points. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a schematic diagram showing a light projection system of one example distance sensor according to examples of the present disclosure.

[0010] Figure 2 shows a pattern of light that can be formed by Figure 1 a light projection system of

[0011] Figure 3A shows a photograph of a portion of a surface of one example diffractive optical element comprising a collimator function according to the present disclosure.

[0012] Figure 3B shows a cross-sectional view of Figure 3A a surface of

[0013] Figure 4 is a schematic diagram showing a light projection system of another example distance sensor according to examples of the present disclosure.

[0014] Figure 5 is a simplified schematic diagram showing one example distance sensor in which examples of the disclosed diffractive optical element comprising a collimator function can be employed.

[0015] Figure 6is a flowchart showing one example method for measuring a distance from a distance sensor to an object.

[0016] Figure 7 depicts a high-level block diagram of one example electronic device for measuring a distance from a distance sensor to an object. DETAILED DESCRIPTION

[0017] The present disclosure broadly describes a diffractive optical element including a collimator function for use in distance measurement and other optical applications. As described above, a sensor for measuring distance can project a pattern of light (e.g., infrared light) onto a surface of an object whose distance is being measured. The pattern of light can include a plurality of discrete light points, where each light point is created when a single beam of light emitted from the distance sensor is incident on the surface of the object. The distance to the object can then be calculated based on the appearance of the pattern. In some examples, the plurality of beams of light used to create the pattern are created by splitting a single beam of coherent light emitted by a light projection system of the distance sensor using a diffractive optical element. Distance sensors including diffractive optical elements for splitting a beam of coherent light are described, for example, in U.S. Patent Application Serial Nos. 14 / 920,246, 15 / 149,323, and 15 / 149,429.

[0018] Coherent light projected from an emitter of a semiconductor laser will typically exhibit some degree of beam divergence, i.e., the beam diameter or radius increases with distance from the light source. The increase in beam diameter or radius can include an angular measure referred to as a "divergence angle." Conventional techniques for adjusting the divergence angle involve using a collimator lens either before or after the beam is split by the diffractive optical element.

[0019] Furthermore, many conventional distance sensors also utilize a vertical cavity surface emitting laser (VCSEL) light source to produce the beam of light. Some designs can employ a single VCSEL emitter, while other designs can employ an array in which multiple VCSEL emitters are densely arranged. In cases where an array of VCSEL emitters is employed, the projection directions of the individual emitters will be parallel to one another, and the beams of light emitted from each emitter will have some degree of spread (i.e., the width of the beam increases with distance from the emitter). Thus, in order to project the light emitted by the VCSEL array in a defined size according to the arrangement of the emitters, it can be necessary to project the light with a constant magnification (spread of the divergence angle).

[0020] For example, in a distance sensor configuration in which a collimator lens is located between a VCSEL array and a diffractive optical element (i.e., adjusting the divergence angle of the coherent light beams before the light beams are split by the diffractive optical element), the collimator lens will not only control the divergence angle of each light beam, but will also simultaneously magnify and project the pattern created by the multiple light beams. In a distance sensor configuration using a single VCSEL emitter (or edge-emitting laser (EEL)), the coherent light beam emitted by the emitter can similarly be shaped to present a desired spread angle (e.g., parallel light) through a collimator lens before being split by a diffractive optical element to form a desired pattern.

[0021] In a distance sensor configuration in which a diffractive optical element is located between a single VCSEL emitter and a collimator lens, the diffractive optical element splits the coherent light beam emitted by the VCSEL emitter into multiple light beams, which can then be shaped by the collimator lens to present an arbitrary spread angle (e.g., parallel light) projected onto a surface. In this case, the pattern created by the diffractive optical element (which can present a corresponding divergence angle) can be made parallel to each other by the collimator lens. In the case of using a VCSEL emitter array instead of a single VCSEL emitter, the spread angle of each light beam exiting the diffractive optical element can be shaped by the position of the collimator lens and the optical power of the collimator lens (i.e., the degree to which the collimator lens converges light). At the same time, the magnification projection specification of the VCSEL array can also be defined by the position and optical power of the collimator lens.

[0022] Examples of the present disclosure employ a diffractive optical element that includes collimator functionality, essentially combining the functionality of a diffractive optical element and a collimator lens into a single component. This reduces the total number of components required to control the projection of a pattern of light for distance sensing applications, which in turn reduces the size and manufacturing cost of the equipment. Previous attempts to combine the functionality of a diffractive optical element and a collimator lens have employed diffractive patterns that employ tilted surfaces (e.g., Fresnel facets), which are difficult to manufacture and produce phase distributions that are not optimized in terms of diffraction efficiency, noise, and pattern uniformity. In contrast, in one example, the combined functionality is achieved by creating a stepped diffractive pattern on the surface of the diffractive optical element in the same plane as the split pattern. An example of a stepped pattern includes a multilayer binary stepped diffractive pattern that has no tilted surfaces. The proposed patterning of the disclosed diffractive optical element is easier to manufacture than a tilted diffractive grating and is better optimized in terms of diffraction efficiency, noise, and pattern uniformity.

[0023] Figure 1 is a schematic diagram showing a light projection system 100 of one example distance sensor according to examples of the present disclosure. In other words, Figure 1A portion of a distance sensor is shown, which projects a light pattern from which distance can be calculated, but other components of the distance sensor, such as a light receiving system and processor for capturing an image of the light pattern and calculating distance based on the image, are omitted.

[0024] like Figure 1 As shown, the light projection system 100 of an exemplary distance sensor typically includes a transmitter 102 and a diffractive optical element 104. In one example, the transmitter 102 includes a VCSEL transmitter. The VCSEL transmitter may more specifically include individual VCSEL transmitters 1061-106. n (Hereinafter referred to individually as “VCSEL emitter 106” or collectively as “VCSEL emitter 106”). Each VCSEL emitter 106 may include a laser source capable of emitting a beam of light (e.g., infrared light) having a wavelength invisible to the human eye but visible to the light receiving system of the exemplary distance sensor.

[0025] Figure 1 The corresponding central emitting axes 1081-108 are shown for each of the VCSEL emitters 106. n (Hereinafter referred to individually as "Axis 108" or collectively as "Axis 108"). Furthermore, Figure 1 A coherent beam 110 emitted from VCSEL transmitter 1061 is shown. VCSEL transmitters 1062 and 106... n A coherent beam can be emitted in a similar manner; however, for simplicity, in Figure 1 Such a beam is not shown. In one example, microlens 114 may optionally be positioned above emitter 102.

[0026] A diffractive optical element 104 is located between the emitter 102 and the exit pupil (not shown) of the light projection system 100, through which emitted light exits the distance sensor. Furthermore, a positioning member 116 can be used to maintain a precise alignment between the emitter 102 and the diffractive optical element 104. In one example, the positioning member 116 is formed of plastic or a polymer, such as a liquid crystal polymer, to facilitate precise molding.

[0027] In one example, the diffractive optical element 104 includes a collimator function, as described in further detail below. That is, in addition to splitting each coherent beam emitted by the emitter 102 (e.g., similar to beam 110) into multiple beams, the diffractive optical element 104 can also shape the multiple beams to present an arbitrary diffusion angle θ projected onto the surface. Figure 1the magnification function illustrated by the angle φ. In one example, the optical power of the diffractive optical element 104 is similar to the optical power of a convex lens. That is, the diffractive optical element 104 can control the divergence angle of the light beams projected by the emitters 102 and can also magnify the projected pattern when the emitters 102 include an array of VCSEL emitters.

[0028] For example, as Figure 1 illustrated, a coherent light beam 110 can be emitted by a VCSEL emitter 1061. When the coherent light beam 110 enters the diffractive optical element 104, the diffractive optical element 104 splits the coherent light beam 110 into a plurality of light beams 1121-112 m (hereinafter referred to individually as “light beam 112” or collectively as “light beams 112”). Moreover, since the diffractive optical element 104 has been configured to also perform a collimator function, the diffractive optical element 104 will shape the plurality of light beams 112 to exhibit a spread angle Θ. In one example, shaping the plurality of light beams 112 by the diffractive optical element 104 can result in some of the light beams 112 being oriented substantially parallel to one another (i.e., parallel within some pre-defined tolerance). For example, as Figure 1 illustrated, light beams 1121and 1122are parallel to one another; light beams 1123and 1124are parallel to one another; light beams 1125and 1126are parallel to one another; light beams 1127and 1128are parallel to one another; and light beams 1129and 112 m are parallel to one another. The splitting and shaping of the coherent light beams emitted by the VCSEL emitters 1062and 106 n may be performed in a similar manner.

[0029] The result is a pattern of spots of light projected onto a surface, where each spot is formed when one of the plurality of light beams is incident on the surface. For example, Figure 2 illustrates a pattern 200 of light that can be formed by the light projection system 100 of Figure 1 As shown, the pattern 200 includes a plurality of individual light spots 202, which can be magnified by the collimator function of the diffractive optical element 104. Each light spot 202 can be formed by one of the plurality of light beams that exit the diffractive optical element 104. Moreover, each set of light beams that is split from a single coherent light beam (e.g., the plurality of light beams 112 that are split from the coherent light beam 110) can form a sub-pattern 204, which can be repeated to form the pattern 200. That is, each coherent light beam emitted by the emitters 102 can create an instance of the sub-pattern 204 once split; thus, when all of the coherent light beams emitted by the emitters 102 create respective instances of the sub-pattern 204 (such that the sub-pattern 204 is repeated across a plurality of respective portions 2061-206 oWhen repeated, the pattern 200 is created. While the repeated sub-patterns 204 in each section 206 appear to present a regular or repeating arrangement of dots 202, it should be appreciated that the repeated sub-patterns 204 can also present an irregular or arbitrary arrangement of dots 202 in other examples.

[0030] As noted above, the diffractive optical element is designed to not only split the light beam that enters the diffractive optical element, but also to collimate the light beams that are created by the splitting. Figure 3A A photograph showing a portion of a surface 300 of one exemplary diffractive optical element including a collimator function according to the present disclosure is shown. Figure 3B A photograph showing a portion of a surface 300 of one exemplary diffractive optical element including a collimator function according to the present disclosure is shown. Figure 3A A cross-sectional view of the surface 300 is shown. The exemplary diffractive optical element can be a diffractive optical element 104 of Figure 1 a diffractive optical element 104 of

[0031] As shown, in one example, the surface 300 of the diffractive optical element can be designed to include an irregular pattern of binary steps. The irregular pattern of binary steps can be etched into, for example, a glass substrate. Each step can include an extension (i.e., a flat raised surface) and a riser (i.e., a height of the flat raised surface) that is oriented at a substantially ninety degree angle relative to the extension. In other words, the steps do not include a sloped surface. For example, Figure 3A and 3B represent an extension 302 and a riser 304 of one of the plurality of steps of the surface 300.

[0032] In one example, as shown in Figure 3A and 3B the pattern created by the steps is irregular in the sense that different steps can have extensions and / or risers of different sizes and / or shapes. However, as shown, the extensions of all of the steps are oriented substantially parallel to each other and parallel to the base of the surface 300, while the risers of all of the steps are also oriented substantially parallel to each other. Thus, while the extensions and risers of all of the steps are oriented parallel to each other, they are not necessarily coplanar with each other (e.g., coplanar with less than all of the other steps). In other words, the surface of the diffractive optical element can include multiple (i.e., two or more) stages or layers 3061-306 i When viewed from above, the pattern on the diffractive optical element can resemble a series of concentric circles.

[0033] Figure 3A and 3B The pattern shown in FIGS. 1-3 is capable of splitting a coherent light beam into a plurality of light beams, and of collimating the plurality of light beams to control a divergence angle. Thus, its surface is designed to present Figure 3A and 3BThe diffractive optical element of the illustrated pattern can perform the function of both a diffractive optical element and a collimator lens, but in a single component. In one example, Figure 3A and 3B The pattern illustrated in FIG. 1 is formed in a surface if the diffractive optical element 104 is facing the emitter 102.

[0034] Figure 4 is a schematic diagram illustrating a light projection system 400 of another example distance sensor according to examples of the present disclosure. Like Figure 1 similarly, Figure 4 illustrates a portion of a distance sensor that projects a light pattern from which a distance can be computed, but omits other components of the distance sensor, such as a light receiving system and a processor for capturing an image of the light pattern and computing a distance based on the image.

[0035] As Figure 4 illustrated, the light projection system 400 of the example distance sensor generally includes an emitter 402 and a diffractive optical element 404. In one example, the emitter 402 includes a VCSEL emitter. However, unlike the emitter 101 of Figure 1 which includes an array of individual VCSEL emitters 106, the emitter 402 includes a single VCSEL emitter 406. The VCSEL emitter 406 can include a laser light source (e.g., infrared light) capable of emitting a beam of light at a wavelength that is not visible to the human eye but is visible to the light receiving system of the example long distance sensor. Figure 4 A central light emission axis 408 is also illustrated for the VCSEL emitter 406. Further, Figure 4 a coherent light beam 410 emitted from the VCSEL emitter 406 is illustrated.

[0036] The diffractive optical element 404 is positioned between the emitter 402 and an exit pupil (not illustrated) of the light projection system 400 via which emitted light exits the distance sensor. Further, a positioning member 416 can be used to maintain a strict aligned positional relationship between the emitter 402 and the diffractive optical element 404.

[0037] In one example, the diffractive optical element 404 includes a collimator function as described above. That is, in addition to splitting the coherent light beam 410 emitted by the emitter 402 into a plurality of light beams, the diffractive optical element 404 can also shape the plurality of light beams to exhibit an arbitrary spread angle projected onto a surface.

[0038] For example, as Figure 4 illustrated, the coherent light beam 410 can be emitted by the VCSEL emitter 406. When the coherent light beam 410 enters the diffractive optical element 404, the diffractive optical element 404 will split the coherent light beam 410 into a plurality of light beams 4121to 412m (both individually referred to as "light beam 412" or collectively referred to as "light beams 412"). Moreover, since the diffractive optical element 404 has been configured to also perform a collimator function, the diffractive optical element 404 will shape the plurality of light beams 412 to exhibit an arbitrary spread angle. In one example, shaping the plurality of light beams 412 by the diffractive optical element 404 can cause some of the light beams 412 to be directed substantially parallel to each other (i.e., parallel within some predefined tolerance). For example, as shown, light beams 4121 and 4122 are parallel to each other; light beams 4123 and 4124 are parallel to each other; light beams 4125 and 4126 are parallel to each other; light beams 4127 and 4128 are parallel to each other; and light beams 4129 and 412 Figure 4 are parallel to each other. m

[0039] The distance sensor of the present disclosure employing a diffractive optical element including a collimator function can be used in a variety of distance sensing schemes and applications. For example, the pattern projected by the disclosed distance sensor can be used to calculate distance according to triangulation using multi-point projection (e.g., where distance is calculated from the projection of a regular point pattern, such as a grid, a code pattern where points are arranged to form a code according to a specified rule, or a pseudo-random pattern where the regularity of the arrangement of points is minimized), time-of-flight using multi-point projection (e.g., where light points are pulsed), a stereo system using multi-point projection (e.g., as a support for feature detection), or triangulation distance measurement (e.g., by projecting multiple light bars instead of light points). Such a distance sensor can be incorporated into devices including mobile phones, personal computers, and other devices where a small form factor and low manufacturing cost are desired.

[0040] Such a distance sensor can also be used in applications including face authentication, gesture recognition, and three-dimensional recognition. The appropriate pattern for the application can be achieved by varying the arrangement and size of the emitters (e.g., the number and arrangement of individual emitters in an array).

[0041] Figure 5 is a simplified schematic diagram showing one example distance sensor 500 in which an example of the disclosed diffractive optical element including a collimator function can be employed. The distance sensor 500 generally includes a processor 502, a light projection system 504, and a light reception system 506.

[0042] The processor 502 can include a hardware processor element 602, such as a central processing unit (CPU), a microprocessor, or a multi-core processor. The processor 502 can be configured to control the operation of both the light projection system 504 and the light reception system 506, as described in further detail below.

[0043] The light projection system can be similar to the light projection system 100 of FIG. 1.​Figure 1 and 4 The light projection system can be configured in the manner of the light projection systems shown in FIGS. 1-3 and discussed above. Thus, the light projection system can include a laser light source (e.g., a single emitter or an array of emitters) and a diffractive optical element that includes a collimator function that is patterned to both: (1) split a coherent light beam emitted by the laser light source into a plurality of light beams; and (2) collimate the plurality of light beams to control a divergence angle of light emitted by the light projection system 504. The diffractive optical element including the collimator function can also control a magnification of a projection pattern (i.e., an arrangement of light points) 508 projected by the light projection system 504 into the surface 510. The processor 502 can control the light projection system 504 to project the pattern 508 (e.g., by sending a signal instructing the emitter(s) to emit light at a specified time and / or for a specified duration). Although Figure 5 The exemplary pattern 508 shown in FIG. 4 presents a regular or repeating arrangement of points, but it will be appreciated that in other examples the pattern 508 can also present an arbitrary or non-uniform (e.g., non-repeating) arrangement of points.

[0044] The light reception system 506 can include an image sensor (e.g., a camera) and other optics (e.g., a filter) that capture an image of the pattern 508 projected onto the surface 510. As noted above, the pattern 508 can be invisible to the human eye due to the wavelength of the light emitted by the light projection system 504, but can be visible to a properly configured image sensor (e.g., a photodetector) of the light reception system 506. The processor 502 can control the light reception system 506 to capture an image of the pattern (e.g., by sending a signal instructing the light reception system to capture an image at a specified time). The image captured by the light reception system 506 can be forwarded to the processor 502 for distance computation.

[0045] The processor 502 can compute a distance to the surface 510 based on an appearance of the pattern 508 in the image captured by the light reception system 506. For example, the processor 502 can store an image or known configuration of the pattern 508 and can compare the captured image to the stored image and / or known configuration to compute the distance, e.g., using triangulation, time-of-flight, or other techniques. For example, the distance can be computed according to any of the methods described in U.S. Patent Application Serial Nos. 14 / 920,246, 15 / 149,323, and 15 / 149,429.

[0046] Figure 6 is a flowchart illustrating one exemplary method 600 for measuring a distance from a distance sensor to an object. The method 600 may, for example, be performed by a distance sensor including at least one processor (e.g., a microprocessor, a microcontroller, a digital signal processor, a graphics processing unit, a physics processing unit, a field programmable gate array, an application specific integrated circuit, or any other suitable processing device or devices) and a memory that stores instructions executable by the at least one processor for performing the functions of the distance sensor as described herein. The method 600 may, for example, be performed by a distance sensor as described in U.S. Patent Application Serial No. 15 / 149,323. Figure 5the processor 502 of the distance sensor 500) executes. Alternatively, the method 600 can be performed by a processing system of a computing device (e.g., the computing device 700 shown in FIG. 7 and described in further detail below). For example, the method 600 is described as being performed by a processing system. Figure 7 the processor 502 of the distance sensor 500) executes. Alternatively, the method 600 can be performed by a processing system of a computing device (e.g., the computing device 700 shown in FIG. 7 and described in further detail below). For example, the method 600 is described as being performed by a processing system.

[0047] The method 600 can begin at step 602. At step 604, the processing system of the distance sensor can cause the light projection system of the distance sensor to project a pattern of light onto an object, where the light projection system includes a diffractive optical element that includes a collimator function. The light projection system of the distance sensor can include, for example, a laser light source that emits one or more light beams (e.g., infrared light) having a wavelength that is substantially invisible to the human eye. The light projection system of the distance sensor can additionally include a diffractive optical element whose surface is patterned (e.g., includes a binary step pattern of multiple layers) as described above to achieve both (1) splitting of the light beam(s) emitted by the laser light source into a plurality of additional light beams and (2) collimating the plurality of additional light beams to control a spread angle and magnification of the light pattern.

[0048] Accordingly, the light projection system can project a plurality of light beams. When each of the plurality of light beams is incident on the object, the light beam creates a light point (e.g., a dot or other shape) on the object. The plurality of light points created by the plurality of light beams collectively form a light pattern on the object. The light pattern can include a predefined arrangement of the plurality of light points. For example, the plurality of light points can be arranged into a grid including a plurality of rows and a plurality of columns, or can be arranged to form vertical or horizontal bars.

[0049] At step 606, the processing system can cause the light receiving system of the distance sensor to capture an image of the light pattern projected onto the object. As described above, the light receiving system of the distance sensor can include, for example, one or more lenses and an imaging sensor that collectively form a camera. The imaging sensor can include an array of photodetectors and optional filters that are capable of detecting the light points of the pattern. For example, the photodetectors can include infrared photodetectors, and the filters can include infrared bandpass filters.

[0050] At step 608, the processing system can compute a set of three-dimensional coordinates of at least some of the plurality of light points based on appearances of the at least some light points in the image and knowledge of a trajectory of the at least some light points. The set of three-dimensional coordinates of the light points can include (x, y, z) coordinates, where the z coordinate can measure a distance (or depth) of the point from the distance sensor. The trajectory of the point can include a range of movement over which a location of the point can vary as a function of distance to the object. The trajectory of each of the plurality of light points can be learned through a calibration of the distance sensor prior to performing the method 600.

[0051] The method 600 can then end at step 610.

[0052] It should be noted that, although not explicitly specified, some of the blocks, functions, or operations of the method 600 above can include storing, displaying and / or outputting information. In other words, any data, records, fields, and / or intermediate results, which are stated in the above description of the method 600 can be stored, displayed, and / or outputted to another device depending on the particular application. Figure 6

[0053] Figure 7 A high-level block diagram of one exemplary electronic device 700 for measuring a distance from a distance sensor to an object is depicted. As such, the electronic device 700 can be implemented as a processor of an electronic device or system, such as a distance sensor.

[0054] As shown, the electronic device 700 includes a hardware processor element 702, such as a central processing unit (CPU), a microprocessor, or a multi-core processor; a memory 704, such as random access memory (RAM) and / or read only memory (ROM); a module 705 for measuring a distance from a distance sensor to an object; and various input / output devices 706, such as storage devices, including but not limited to, a tape drive, a floppy disc drive, a hard disk drive, or a compact disc drive, a receiver, a transmitter, a display, output ports, input ports, and a user input device, such as a keyboard, a keypad, a mouse, a microphone, a camera, a laser light source, an LED light source, etc. Figure 7 Although one processor element is shown, it should be understood that more than one processor element can be employed. Furthermore, although one electronic device 700 is shown in the figure, if the method(s) as described above is implemented in a distributed or parallel manner, the electronic device 700 is intended to represent each of the electronic devices which can be employed in such a manner.

[0055]

[0056] ​​It should be noted that the present disclosure can be implemented by machine readable instructions and / or a combination of machine readable instructions and hardware, for example, using an application specific integrated circuit (ASIC), programmable logic array (PLA) including a field programmable gate array (FPGA), or a state machine deployed on a hardware device, general purpose computer, or any other hardware equivalent, for example, computer readable instructions related to the above method(s) can be used to configure a hardware processor to perform the blocks, functions, and / or operations of the above method(s).

[0057] In one example, instructions and data (e.g., machine readable instructions) for the present module or process 705 for measuring a distance from a distance sensor to an object can be loaded into memory 704 and executed by hardware processor element 702 to implement the blocks, functions or operations as discussed above in connection with method 600. Moreover, when a hardware processor executes instructions to perform “operations”, this can include the hardware processor performing the operation directly and / or facilitating, directing, or cooperating with another hardware device or component to perform the operation.

[0058] A processor executing machine readable instructions related to the above method(s) can be considered a programmed processor or special purpose processor. As such, the present module 705 of the present disclosure for measuring a distance from a distance sensor to an object can be stored on a tangible or physical (broadly non-transitory) computer readable storage device or medium, such as a volatile memory, non-volatile memory, ROM memory, RAM memory, magnetic or optical drive, device or disk, etc. More specifically, a computer readable storage device can include any physical device providing the ability to store information, such as data and / or instructions, to be accessed by a processor or electronic device (e.g., a computer or controller of a security sensor system).

[0059] It should be understood that variations and other features and functions of the above-disclosed can be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, or equivalents can be devised by those skilled in the art using no more than the knowledge currently available and, thus, are also intended to be within the scope of the following claims.

Claims

1. A distance sensor, comprising: a light projection system to project a pattern comprising a plurality of light points onto an object, the light projection system comprising: a laser light source to project coherent light; and a diffractive optical element having a plurality of layers etched to form a binary stepped pattern, wherein the plurality of layers are configured to split the coherent light into a plurality of light beams, wherein each of the plurality of light beams forms one of the plurality of light points, and wherein the plurality of layers are further configured to control a divergence angle of the plurality of light beams; a light receiving system to capture an image of the pattern projected onto the object; and a processor to calculate a distance to the object based on an appearance of the pattern in the image and based on knowledge of a trajectory of the plurality of light points, wherein each of the binary stepped patterns comprises an irregular arrangement of a plurality of steps, and each of the plurality of steps comprises a run of no slope and a rise, wherein the arrangement of the plurality of steps is irregular in the sense that different steps have different sized and / or shaped runs and different rises.

2. The distance sensor of claim 1, wherein, The laser light source comprises a single vertical cavity surface emitting laser that emits a single coherent light beam toward the diffractive optical element.

3. The distance sensor of claim 1, wherein, The laser light source comprises a single edge emitting laser that emits a single coherent light beam toward the diffractive optical element.

4. The distance sensor of claim 1, wherein, The laser light source comprises an array of a plurality of vertical cavity surface emitting lasers that collectively emit a plurality of coherent light beams toward the diffractive optical element.

5. The distance sensor of claim 4, wherein, The plurality of layers are further configured to magnify the pattern.

6. The distance sensor of claim 1, wherein, The run of each of the plurality of steps is parallel to the runs of other steps of the plurality of steps but is coplanar with fewer than all of the runs of the other steps.

7. The distance sensor of claim 1, further comprising a positioning member positioned to maintain an aligned positional relationship between the laser light source and the diffractive optical element.

8. The distance sensor of claim 1, wherein, The plurality of layers are defined in a surface of the diffractive optical element facing the laser light source.

9. The distance sensor of claim 1, wherein, The coherent light comprises a wavelength of light that is not visible to the human eye but is visible to a photodetector of the light receiving system.

10. The distance sensor of claim 8, wherein, The plurality of light beams form a point pattern that is repeated on the surface by other plurality of light beams split from the coherent light by the diffractive optical element.

11. The distance sensor of claim 10, wherein, The point pattern comprises a regular pattern.

12. The distance sensor of claim 10, wherein, The point pattern comprises an irregular pattern.

13. A method for distance measurement, comprising: causing, by a processing system of a distance sensor comprising at least one processor, a light projection system of the distance sensor to project a pattern onto an object, wherein the pattern comprises a plurality of light points, and wherein the plurality of light points are formed by a diffractive optical element of the light projection system comprising a collimator function; causing, by the processing system, a light receiving system of the distance sensor to capture an image of the pattern projected onto the object; and causing, by the processing system, a processor of the distance sensor to calculate a distance to the object based on an appearance of the pattern in the image and based on knowledge of a trajectory of the plurality of light points. computing, by the processing system, a set of three-dimensional coordinates of at least some of the plurality of light points, wherein the computing is based on appearances of the at least some points in the image and knowledge of trajectories of the at least some points, wherein the diffractive optical element comprises a plurality of layers etched to form binary-echelette patterns, wherein the plurality of layers are configured to split coherent light emitted by a laser light source of the light projection system into a plurality of light beams, wherein each of the plurality of light beams forms one of the plurality of light points, and wherein the plurality of layers are further configured to control a divergence angle of the plurality of light beams, and wherein each of the binary-echelette patterns comprises an irregular arrangement of a plurality of echelettes, and each of the plurality of echelettes comprises a run of zero slope and a step-up, wherein the arrangement of the plurality of echelettes is irregular in the sense that different echelettes have different sized and / or shaped runs and different step-ups.

14. The method of claim 13, wherein, the laser light source comprises a single vertical-cavity surface-emitting laser that emits a single coherent light beam toward the diffractive optical element.

15. The method of claim 13, wherein, the laser light source comprises a single edge-emitting laser that emits a single coherent light beam toward the diffractive optical element.

16. The method of claim 13, wherein, the laser light source comprises an array of a plurality of vertical-cavity surface-emitting lasers that collectively emit a plurality of coherent light beams toward the diffractive optical element.

17. The method of claim 13, wherein, each of the binary-echelette patterns comprises an irregular arrangement of a plurality of echelettes, and each of the plurality of echelettes comprises a run of zero slope and a step-up.

18. A non-transitory machine-readable storage medium encoded with instructions executable by a processing system of a distance sensor comprising at least one processor, wherein, the instructions, when executed by the processing system, cause the processing system to perform operations comprising: causing a light projection system of the distance sensor to project a pattern onto an object, wherein the pattern comprises a plurality of light points, and wherein the plurality of light points are formed by a diffractive optical element of the light projection system that includes a collimator function; causing a light reception system of the distance sensor to capture an image of the pattern projected onto the object; and computing a set of three-dimensional coordinates of at least some of the plurality of light points, wherein the computing is based on appearances of the at least some points in the image and knowledge of trajectories of the at least some points, wherein the diffractive optical element comprises a plurality of layers etched to form binary-echelette patterns, wherein the plurality of layers are configured to split coherent light emitted by a laser light source of the light projection system into a plurality of light beams, wherein each of the plurality of light beams forms one of the plurality of light points, and wherein the plurality of layers are further configured to control a divergence angle of the plurality of light beams, and wherein each of the binary-echelette patterns comprises an irregular arrangement of a plurality of echelettes, and each of the plurality of echelettes comprises a run of zero slope and a step-up, wherein the arrangement of the plurality of echelettes is irregular in the sense that different echelettes have different sized and / or shaped runs and different step-ups.

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