CN108885260B

CN108885260B - Time-of-flight detector with single axis scanning

Info

Publication number: CN108885260B
Application number: CN201780020792.0A
Authority: CN
Inventors: A·斯庞特; Y·格尔森
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2016-04-08
Filing date: 2017-03-07
Publication date: 2022-06-03
Anticipated expiration: 2037-03-07
Also published as: WO2017176410A1; CN108885260A

Abstract

An apparatus for mapping includes an illumination assembly (123) that projects a line of radiation (122) extending in a first direction across a scene. A detection assembly (145) receives radiation reflected from a scene within a sensing region (148) containing at least part of the line of radiation, and includes a linear array (54, 136) of detector elements (56) and objective optics (52, 146) that focus the reflected radiation from the sensing region onto the linear array. A scanning mirror (46,138) scans the radiation and the sensing region together over the scene in a second direction, the second direction being perpendicular to the first direction. Processing circuitry (64, 66) processes signals output by the detector elements in response to the received radiation in order to construct a three-dimensional (3D) map of the object in the scene.

Description

Time-of-flight detector with single axis scanning

Technical Field

The present invention relates generally to three-dimensional (3D) mapping, and in particular to an apparatus and method for 3D mapping based on projection and sensing of radiation beams.

Background

Various methods are known in the art for optical 3D mapping, i.e. generating a 3D contour of an object surface by processing optical radiation received from the object. Such 3D contours are also referred to as 3D maps, depth maps or depth images, and 3D mapping is also referred to as depth mapping. "optical radiation" includes any and all electromagnetic radiation in the visible, infrared, and ultraviolet portions of the spectrum. In the following description, the term "radiation" is understood to relate to optical radiation.

Some 3D mapping techniques are based on the measurement of the transit time of the optical pulses. For example, U.S. patent application publication 2013/0207970 (the disclosure of which is incorporated herein by reference) describes a scan depth engine in which a mapping device includes an emitter that emits a light beam containing pulses of light, and a scanner configured to scan the light beam over a scene within a predefined scan range. A receiver receives light reflected from the scene and generates an output indicative of the transit time of the pulse to and from a point in the scene. A processor is coupled to control the scanner to scan the light beam over a selected window within the scan range, and the output of the receiver is processed to generate a 3D map of a portion of the scene within the selected window.

Disclosure of Invention

Embodiments of the present invention described below provide improved devices and methods for 3D mapping.

There is thus provided, in accordance with an embodiment of the present invention, apparatus for mapping, including an illumination assembly configured to project a line of radiation extending in a first direction across a scene. The detection assembly is configured to receive radiation reflected from a scene within a sensing region containing at least a portion of the line of radiation and includes a linear array of detector elements and objective optic elements that focus the reflected radiation from the sensing region onto the linear array. The scanning mirror is configured to scan the radiation line and the sensing region together over the scene in a second direction, the second direction being perpendicular to the first direction. The processing circuitry is configured to process signals output by the detector elements in response to the received radiation in order to construct a three-dimensional (3D) map of the object in the scene.

In a disclosed embodiment, the linear array has an array axis aligned along a first direction. In some embodiments, the scanning mirror is configured to rotate about a mirror axis, and the illumination assembly comprises at least one radiation source disposed in a plane defined by the array axis and the mirror axis together with the linear array and the scanning mirror.

In one embodiment, the illumination assembly includes an otherwise linear array of radiation sources configured to emit respective beams of radiation, and projection optics configured to collect and focus the emitted beams to form radiation. Typically, the linear arrays of detector elements and radiation sources have respective axes that are parallel to each other.

Alternatively, the scanning mirror is a second scanning mirror and the illumination assembly includes a radiation source configured to emit a beam of radiation, and the first scanning mirror is configured to receive and scan the emitted beam in a first direction. In a disclosed embodiment of the invention, the first scanning mirror scans at a first speed and the second scanning mirror scans at a second speed, the second speed being slower than the first speed.

In some embodiments, the illumination assembly is configured to emit radiation pulses and the signals output by the detector elements are indicative of respective times of flight of the pulses from points in the scene, and the processing circuitry is configured to construct the 3D map in response to the times of flight. In one embodiment, the detector element comprises an avalanche photodiode. Alternatively, the detector element comprises a single photon avalanche diode. In a disclosed embodiment, the processing circuitry includes a pulse amplifier configured to amplify the signals output by the detector elements and a multiplexer configured to select the detector elements for connection to the pulse amplifier synchronized with the scan rate of the apparatus.

In some embodiments, the scanning mirror is rotatable to scan the radiation and sensing region over a first scene on a first side of the apparatus and over a second scene on a second side of the apparatus, the second side being opposite the first side. In a disclosed embodiment of the invention, the scanning mirror has an opposing first reflective surface and an opposing second reflective surface, and the scanning mirror rotates such that radiation and the sensing region reflect from the first reflective surface when scanning a first scene and radiation and the sensing region reflect from the second reflective surface when scanning a second scene. In one embodiment, the second reflective surface is smaller than the first reflective surface.

There is also provided, in accordance with an embodiment of the present invention, a method for mapping, including projecting a radial line extending in a first direction over a scene. Radiation reflected from a scene within a sensing region of a detector assembly is received by the detector assembly, which includes a linear array of detector elements. Scanning the radiation and sensing region over the scene in a second direction using the scanning mirror, the second direction being perpendicular to the first direction. Signals output by the detector elements are processed in response to the received radiation in order to construct a three-dimensional (3D) map of the object in the scene.

In a disclosed embodiment, receiving radiation includes aligning an array axis of a linear array along a first direction.

In some embodiments, projecting radiation comprises emitting respective radiation beams using a linear array of radiation sources, and collecting and focusing the emitted beams to form the radiation.

In other embodiments, projecting the line of radiation includes scanning the beam along a line in a first direction. In a disclosed embodiment, scanning the beam includes scanning the beam along a line at a first speed, and scanning with the scanning mirror includes scanning the line and the sensing region over the scene at a second speed, the second speed being slower than the first speed.

In a disclosed embodiment of the invention, the scanning radiation beam includes scanning radiation pulses, and the signals indicative of respective times of flight of the pulses are output by the detector elements, and processing the signals includes constructing a 3D map responsive to the times of flight.

The present invention will be more fully understood from the detailed description of embodiments of the invention given below, taken together with the accompanying drawings, in which:

drawings

Fig. 1 is a schematic, pictorial illustration of a 3D mapping system, in accordance with an embodiment of the present invention;

Fig. 2 is a schematic, pictorial illustration showing details of a 3D mapping module, in accordance with an embodiment of the present invention;

fig. 3 is a block diagram that schematically illustrates processing circuitry for 3D mapping, in accordance with an embodiment of the present invention;

fig. 4 is a schematic front view of a 3D mapping module according to another embodiment of the present invention;

fig. 5 is a schematic, pictorial illustration showing details of the 3D mapping module of fig. 4, in accordance with an embodiment of the present invention; and

fig. 6 is a schematic, pictorial illustration showing a posterior view of the 3D mapping module of fig. 4, in accordance with an embodiment of the present invention.

Detailed Description

In some 3D mapping systems based on time-of-flight measurements, such as described in the aforementioned U.S. patent application publication 2013/0207970, the same scanning mirror is used to scan a pulsed light beam emitted toward the scene and the sensing area of a detector that senses the reflected radiation in both the horizontal and vertical directions. This approach is advantageous to ensure that the emitted and received beam axes are aligned with each other, but imposes significant limitations on the optical design of the system. In other systems, separate scanning mirrors are used to scan the emission beam and the sensing region of the detector, thereby alleviating optical limitations, but there can be difficulties in aligning and synchronizing the sensing region with the emission beam.

Embodiments of the present invention address these difficulties by projecting radiation and capturing the reflected radiation using a linear array of detectors, in which a scanning mirror scans the radiation and sensing area of the detectors over a scene. This approach both simplifies the optical design of the scanning module and avoids the mechanical problems associated with fast scanning, while achieving a compact and robust module design. In some of these embodiments, the scanning mirror is rotatable to scan the emission beam and the sensing region over a first scene on a first side of the device and a second scene on a second side of the opposite side of the device, enabling it to create a 3D map of one or both of these scenes.

In a disclosed embodiment, the mapping device includes an illumination assembly that projects a radial line extending in a direction across the scene, such as in a horizontal direction. In some embodiments described below, the illumination assembly includes a linear array of radiation sources that emit respective beams of radiation, wherein the projection optics collect and focus the emitted beams to form radiation. Alternatively, however, the illumination assembly may comprise a single radiation source with suitable optical elements.

The detection component receives radiation reflected from the scene within a sensing region that contains a projected line of radiation (or at least a portion of a projected line). To this end, the detection assembly includes a linear array of detector elements and objective optical elements that focus reflected radiation from the sensing region onto the linear array. The sensing region is generally elongated and narrow, parallel to and aligned with the line of radiation. For this purpose, the axes of the array of detector elements may also be aligned in the same direction as the radiation.

The scan mirror scans the radiation and the sensing region together over the scene in a direction perpendicular to the radiation. Thus, for example, if the illumination assembly projects a horizontal line, the scan mirror scans the line vertically, and vice versa. The benefit of this arrangement is that the scan mirror can scan relatively slowly (e.g., map at 30Hz at a standard video refresh rate) and does not require high speed scanning components.

Other embodiments of the present invention use a hybrid approach, combining a scanning illumination beam with a fixed array of detector elements for sensing the reflected radiation. The first scanning mirror scans the emitted light beam over the scene in a first direction, as described above, while the second scanning mirror scans both the emitted light beam and the sensing area of the detector array over the scene in a second direction, the second direction being perpendicular to the first direction.

Processing circuitry processes signals output by the detector elements in response to the received radiation to construct a 3D map of the object in the scene. In the embodiments described below, the illumination assembly emits pulses of radiation, and the detector elements output signals indicative of respective times of flight of the pulses from points in the scene, which are used by the processor in constructing the 3D map. Alternatively, the devices and techniques described herein may be applied, mutatis mutandis, to other types of 3D mapping systems.

Fig. 1 is a schematic, pictorial illustration of a 3D mapping system, in accordance with an embodiment of the present invention. The system is built around a 3D mapping module 20, which is described in more detail with reference to the following figures. For example, module 20 may be used with a computing device or with a computing device that maps hand 24 for the purpose of detecting gestures by a user. This is but one possible non-limiting application of the present embodiment, and module 20 and other types of devices based on the principles described herein may similarly be applied to other types of systems and used to map various other types of objects.

As shown in FIG. 1, module 20 emits a pulsed beam 26 of radiation through an exit aperture 28 toward a scene including hand 24. The module 20 scans the light beam, such as a raster scan, over the scene in a predefined scan pattern 32, which is generated by the cooperative operation of the two scan mirrors, as shown in fig. 2. Each pulse emitted from the exit aperture 28 illuminates a successive point 30 in the scene along a scan pattern, and the spots in each row of the scan pattern 32 define a projected line of radiation. Radiation 34 reflected from the scene at each spot 30 is collected by an entrance aperture 36 of the module 20 and detected by a detection assembly in the module, which is also shown in subsequent figures. Processing circuitry in or associated with module 20 processes signals output by the detection assembly in response to reflected radiation 34 received through aperture 36 in order to construct a 3D map of hand 24 and/or other objects in the scene.

For convenience, in the following description, the frontal plane of module 20 is considered to be the X-Y plane, as shown in FIG. 1, while the Z-axis corresponds to the direction of propagation of beam 26 when not reflected, i.e., approximately at the center of scan pattern 32. Module 20 scans beam 26 in the X-Y plane. In mode 32, the X-axis of the scan is considered the "fast" axis, which is traversed multiple times by the beam 26 during each scan over the scene, while the Y-axis is considered the "slow" axis. However, the choice of these axes is arbitrary, and the module 20 may be configured to generate other scan patterns with different scan axes, as will be apparent to those skilled in the art upon reading this description.

Fig. 2 is a schematic, pictorial illustration showing details of the 3D mapping module 20, in accordance with an embodiment of the present invention. The mapping module 20 includes an illumination assembly including a radiation source 40 that emits a beam 26, and a scanning mirror 42 that receives and reflects the beam 26 from the light source 40. In a typical embodiment, radiation source 40 comprises a laser diode that emits ultrashort pulses and has a duration of about one millionth of a second. To minimize the size and weight of the module 20 and achieve high speed scanning, the mirror 42 is typically small (e.g., less than 10 millimeters in diameter) in this embodiment. Such mirrors may be fabricated by micro-electro-mechanical systems (MEMS) technology, such as described in the above-mentioned U.S. patent application publication 2013/0207970, with electromagnetic, electrostatic or piezoelectric actuators. Alternatively, mirror 42 may comprise a rotating polygon or any other suitable type of scanning mirror known in the art.

In other embodiments (not shown in the figures), the mirror 42 may be shared by multiple radiation sources, with the sources arranged such that their beams illuminate the mirror at different angles, thereby scanning over different portions of the scene and increasing the pixel throughput of the module 20 while reducing the required mirror scan amplitude.

Mirror 42 rotates about axis 44 to scan beam 26 in the X direction over the scene. The second mirror 46 rotates about an axis 48 to scan the beam 26 in the Y direction over the scene. In general, a small lightweight mirror 42 may rotate at high speeds in a resonant scan mode, while mirror 46 rotates at slower speeds. Accordingly, the mirror 46 may comprise a MEMS device or any other suitable type of rotating mirror.

If the beam output by source 40 is not sufficiently collimated, an optical element 50 may be added in the beam path to improve collimation. The optical element 50 may be positioned in the position shown in fig. 2 or any other suitable position, such as between the source and the mirror 42 or between the mirror 42 and the mirror 46. Additionally or alternatively, the optical element 50 may be used to enhance the scanning range, for example, as described in the above-mentioned U.S. patent 9,098,931. Furthermore, the distance between mirror 42 and mirror 46 is typically less than that shown in FIG. 2, where mirror 42 is located in or near the plane of the entrance pupil of the optical receiver.

The reflected radiation 34 from each spot 30 is received by a detection assembly comprising a detector element 56 and a linear array 54 of objective optics 52 which focus the reflected radiation onto the detector element. Optical element 52 typically comprises a multi-element lens having a wide acceptance angle and may be positioned between array 56 and mirror 46, rather than in the position shown in FIG. 2. It is desirable that the entrance pupil of the lens be close to the mirror 46 to achieve a compact design. Additionally or alternatively, the optical element 52 comprises a narrow band filter that passes the wavelength of the source 40 while preventing ambient radiation from reading the detector element 56.

Thus, the optical element 52 defines a sensing area of the detection assembly, which is essentially an optical projection of the optical element 52 of the area of the detector element 56. The mirror 46 scans the sensing region, including the hand 24, over the scene in the Y direction while scanning the scan pattern 32 of the emitted beam 26. At least one of the detector elements 56 will then capture the radiation reflected from each spot 30 in the scan pattern. Therefore, the sensing region can be scanned at high speed in the X direction without a collecting mirror.

In the illustrated embodiment, the array 54 includes a single row of detector elements 56 arranged along an array axis, which in this example is parallel to the X-direction, i.e., parallel to the axis 48 of the mirror 46. Alternatively, the array may comprise a plurality of parallel rows of detector elements arranged in this manner. In this geometry, as shown in FIG. 2, most of the critical elements of module 20, including source 40, mirror 42 and mirror 46, and array 56, may be arranged in an X-Y plane containing the array axis and mirror axis 48. This planar arrangement of array elements is very useful for achieving a compact design of the module 20 with a low profile in the Z-direction, as shown in fig. 1.

Fig. 3 is a block diagram that schematically illustrates processing circuitry for use with or in connection with a 3-D mapping module 20, in accordance with an embodiment of the present invention. The processing circuitry responds to the received radiation 34 by the signals output by the detector elements 56 in order to construct a 3D map of the hand 24 (or other object in the scene). The signals output by the detector elements are indicative of the respective times of flight (TOF) of the pulses emitted by the radiation source 40, and the processing circuitry constructs a 3D map by measuring these times of flight.

For this purpose, the detector elements 56 typically include sensitive high-speed photodetectors, such as avalanche photodiodes or Single Photon Avalanche Diode (SPAD) devices. When avalanche photodiodes or similar types of detectors are used, one or more pulse amplifiers, such as high speed transimpedance amplifiers (TIAs), amplify the signals output by the detector elements 56 to generate sharp output pulses for TOF measurements. Although a respective TIA may be coupled to each detector element 56, in fact only one detector will actually receive the reflected radiation at any given time: the sensing area of the detector is aligned along the X-axis with the current position of the emitted beam 26 and the corresponding spot 30. Thus, in the illustrated embodiment, the module 20 includes only a single pulse amplifier 62, and the multiplexer 60 selects the detector element 56 for connection to the pulse amplifier 62, the pulse amplifier 62 being synchronized with the scanning of the scan mirror 42 about the axis 44. In other words, at any point during the scan, the multiplexer 60 connects the input of the amplifier 62 to the output of the detector element 56 at which point the emission beam 26 is aligned.

The pulse output of the amplifier 62 is input to TOF circuitry 64, which TOF circuitry 64 compares the time of arrival of each pulse of the detector 56 with a reference signal indicative of the time at which the emitter 40 emits the pulse and generates a corresponding delay value. For example, the TOF circuit 64 may include a time-to-digital converter (TDC). The depth processing circuit 66 acquires TOF values throughout the scan pattern 32 and combines them into a 3D map of the scene from which the scan began.

No TIA is required when the detector element 56 comprises a SPAD device, but rather an event timing histogram is created and analyzed to determine TOF values for each pixel.

In this embodiment, the resolution of module 20 is not determined by the pitch or number of detector elements 56 in array 54, but by the accuracy of sensing and angular pointing, and the pulse frequency, as the beam from emitter 40 is scanned over the scene. This feature is particularly useful when the detector element 56 includes an APD sensor, as the APD can be larger than the desired pixel size.

Alternatively, other types of processing circuitry including one or more pulse amplifiers may be coupled to the outputs of the detector elements 56. Furthermore, although the disclosed embodiments are particularly directed to TOF-based 3D mapping, the principles of the present invention are similarly applicable to other types of 3D mapping, such as the type based on pattern matching described in U.S. patent 9,098,931, as well as other applications for high-speed optical scanners and detectors.

Referring now to fig. 4 and 5, a 3D mapping module 120 is schematically illustrated according to another embodiment of the present invention. Fig. 4 is a front view, and fig. 5 is an illustration showing details of components of the module. For convenience, in the following description, as in the previous embodiment, the frontal plane of the module 120 is considered to be the X-Y plane, while the Z-axis corresponds to the direction of propagation of radiation 122 emitted from the module 120 when not reflected, i.e., approximately at the center of the module's scan pattern. Line 122 is oriented along the X direction and is scanned along the Y direction by module 120. However, the choice of these axes is arbitrary and is used only for the sake of clarity and convenience of the present description.

The mapping module 120 includes an illumination assembly 123 that includes a linear array 124 of radiation sources that emit respective beams of radiation, and a projection optics 126 that collects and focuses the emitted beams to form a line 122. (herein, the term "line" is used to denote an elongated and narrow area illuminated by the combined beam from array 124, or alternatively, by the scanning beam in the previous embodiment.) in this embodiment, the axis of array 124 is oriented along the X-axis on the lower surface of housing 128 of module 120; and optical element 126 includes a pair of turning mirrors 130 and 132 with a collimating lens 134 therebetween. (steering mirrors 130 and 132 steer the beam axis to a sensing region closer to the array 136 of detector elements, as described further below.) for example, the array 124 may alternatively be mounted on the side of the housing 128, in which case the steering mirror 130 may be eliminated. In a typical embodiment, the radiation sources in array 124 comprise laser diodes that emit ultrashort pulses of infrared radiation in a synchronized manner with each other and for a duration of about one millionth of a second.

The scanning mirror 138 reflects the radiation 122 formed by the optical elements 126 through a window 140 in the housing 128 to the scene to be mapped. Mirror 138 rotates about a mirror axis 142 oriented along the X direction, thereby scanning line 122 over the scene in the Y direction. In the illustrated embodiment, mirror 138 is mounted on bearings 143 and rotated at a desired scan rate by a suitable mechanism 144, such as a motor or magnetic drive. Alternatively, mirror 138 may comprise a MEMS device, as is known in the art, or any other suitable type of beam deflector.

Mirror 138 also reflects radiation returning from the scene to a detection assembly 145, which includes a linear array 136 of detector elements and objective optics 146 that focus the reflected radiation from a sensing region 148 within the scene onto array 136. (to enhance compactness and reduce undesirable geometric effects, the turning mirror 132 may be formed on a slanted surface of one of the lenses in objective optic 146). The sensing region 148 corresponds to a projection of the optical elements 146 of the area of the detector elements in the array 136 onto the scene to be mapped. The line 122 and the sensing region 148 overlap in the plane of the scene being mapped. For good imaging and tracking between the line 122 and the sensing area 148 in the embodiment shown in the figures, the exit pupil 150 of the projection optics 126 and the entrance pupil 152 of the objective optics 146 are coplanar and in close proximity to each other. To minimize the size of the module 120 and reduce the triangulation effect between the emission beam and the sensing region, it is desirable that the plane of the pupil 150 and the pupil 152 be located approximately between the optical element 146 and the mirror 138, and that the array axis of the emission beam and the array axis of the sensing region be collinear in this plane.

In the illustrated embodiment, array 136 includes a single row of detector elements arranged along an array axis, which in this example is parallel to the X-direction, i.e., parallel to axis 142 of mirror 138, and parallel to the axis of line 122 and array 124. Alternatively, array 136 may include a plurality of parallel rows of detector elements arranged in this manner. In this geometry, as shown, most of the critical elements of module 120 may be arranged in an X-Y plane containing the array axis and mirror axis 142, including array 124 and array 136 and mirror 138. This planar arrangement is very useful for achieving a compact design of the module 120 with a low profile in the Z-direction. The

arrays

124 and 136 may be conveniently mounted on a common printed circuit substrate 154, as shown in FIG. 4.

Processing circuitry (such as depth processing circuitry 66 or other types of processing circuitry described above) for use with or in 3D mapping module 120 processes signals output by the detector elements in array 136 in response to radiation reflected from sensing region 148 to construct a 3D map of an object or objects in the scene. The signals output by the detector elements are indicative of respective time of flight (TOF) of pulses emitted by radiation sources in the array 124, and processing circuitry constructs a 3D map based on these time of flight. To this end, the detector elements in the array 136 typically include sensitive high-speed photodetectors, such as avalanche photodiodes or Single Photon Avalanche Diode (SPAD) devices. The configuration and use of these detector types in module 120 is similar to that described above with reference to module 20.

As with the previous embodiments, other types of processing circuitry may be coupled to the outputs of the detector elements, and the principles of this embodiment are similarly applicable to other types of 3D mapping, as well as other applications of high-speed optical scanners and detectors.

Fig. 6 is a schematic, pictorial illustration showing a posterior view of the 3D mapping module 120, in accordance with an embodiment of the present invention. Scanning mirror 138 is rotatable to scan radiation line 122 and sensing region 148 both over a scene on the front side of module 120 shown in fig. 4 and 5 and over another scene on the opposite back side of module 120 shown in fig. 6. (for clarity, the terms "front" and "rear" are used arbitrarily and may be reversed in the context of the device in which the module 120 is installed). The same illumination assembly 123 and detection assembly 145 are used in the pre-scan configuration and the post-scan configuration.

To scan the back side of module 120, mirror 138 may simply be rotated about mirror axis 142 such that the same reflective surface faces the back side. However, to make the module 120 more compact, in this embodiment, the mirror 138 has two opposing reflective surfaces: a front side 156 as shown in fig. 4 and 5 and a back side 158 as shown in fig. 6. Mirror 138 rotates about axis 42 such that line 124 and sensing region 148 reflect from front surface 156 when scanning over a scene on the front side of the module and from back surface 158 when scanning over a scene on the back side. As a result of this configuration, mirror 138 does not need to rotate through the horizontal (X-Z) plane, thus allowing module 120 to be very thin, e.g., less than 5 mm in thickness in the Z direction.

To further reduce the size of module 120, back surface 158 may be made smaller than front surface 156, as shown in FIG. 6, such that mirror 138 has a generally trapezoidal profile in the Y-Z plane. When mapping a scene on the posterior side of module 120, dorsal face 158 reflects lines 124 and sensing region 148 through window 160 in the posterior side of housing 128. A smaller back surface 158 means that the collection aperture of objective optic 146, and thus the sensitivity of detection assembly 145, is less in the post-scan configuration than in the pre-scan configuration. For example, this tradeoff of sensitivity and module size is acceptable when the post-scan configuration is primarily used for nearby scenes, where the intensity of radiation reflected back from the sensing region 148 is relatively high.

Further, the reduced aperture of the optical element 146 in the post-scan configuration may be used to increase the depth of field, which may include objects in close proximity to the module 120. To further increase the depth of field, the back surface 158 of the mirror 138 may be shielded to further reduce the light collection aperture. Alternatively or additionally, the objective optic 146 may have different adjustable focal point positions for short and long range mapping.

It will be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.

Claims

1. An apparatus for mapping, comprising:

an illumination assembly comprising at least one radiation source, and a projection optical element configured to project radiation extending in a first direction across a scene via an exit pupil of the projection optical element;

a detection component configured to receive the radiation reflected from the scene within a sensing region containing at least part of the radiation, and comprising a linear array of detector elements and objective optics that focus the reflected radiation from the sensing region to the linear array via an entrance pupil of the objective optics, wherein the entrance pupil of the objective optics is coplanar with and in close proximity to an exit pupil of the projection optics, wherein the radiation and the sensing region have respective axes that are collinear in a plane containing the exit pupil and the entrance pupil;

a scanning mirror configured to scan the radiation line and the sensing region together over the scene in a second direction, the second direction being perpendicular to the first direction; and

Processing circuitry configured to process signals output by the detector elements in response to the received radiation in order to construct a three-dimensional (3D) map of objects in the scene.

2. The device of claim 1, wherein the linear array has an array axis aligned along the first direction.

3. The apparatus of claim 2, wherein the scanning mirror is configured to rotate about a mirror axis, and wherein at least one radiation source is disposed with the linear array and the scanning mirror in a plane defined by the array axis and the mirror axis.

4. The apparatus of claim 1, wherein at least one radiation source comprises an additional linear array of radiation sources configured to emit respective radiation beams, and wherein the projection optics are configured to collect and focus the emitted beams to form the line of radiation.

5. The apparatus of claim 4, wherein the radiation sources emit radiation pulses synchronously with each other.

6. The apparatus of claim 1, wherein the scanning mirror is a second scanning mirror and at least one radiation source is configured to emit a radiation beam, and the illumination assembly comprises a first scanning mirror configured to receive and scan the emitted beam in the first direction.

7. The apparatus of claim 6, wherein the first scan mirror scans at a first speed and the second scan mirror scans at a second speed, the second speed being slower than the first speed.

8. The apparatus of any of claims 1-4,6, and 7, wherein the illumination assembly is configured to emit radiation pulses, and wherein the signals output by the detector elements are indicative of respective times of flight of the pulses from points in a scene, and the processing circuitry is configured to construct the 3D map in response to the times of flight.

9. The apparatus of claim 8, wherein the detector elements comprise avalanche photodiodes.

10. The apparatus of claim 8, wherein the detector element comprises a single photon avalanche diode.

11. The apparatus of claim 8, wherein the processing circuitry comprises a pulse amplifier configured to amplify the signals output by the detector elements and a multiplexer configured to select detector elements for connection to the pulse amplifier in synchronization with a scan rate of the apparatus.

12. The apparatus of any of claims 1-7, wherein the scanning mirror is rotatable to scan the radiation line and the sensing region both over a first scene on a first side of the apparatus and over a second scene on a second side of the apparatus, the second side being opposite the first side.

13. The apparatus of claim 12, wherein the scanning mirror has opposing first and second reflective surfaces, and wherein the scanning mirror rotates such that the line of radiation and the sensing region reflect from the first reflective surface when scanning over the first scene and the line of radiation and the sensing region reflect from the second reflective surface when scanning over the second scene.

14. The device of claim 13, wherein the second reflective surface is smaller than the first reflective surface.

15. A method for mapping, comprising:

projecting radiation extending in a first direction from at least one radiation source over the scene via an exit pupil of the projection optics;

receiving, via an entrance pupil of an objective optic within a sensing region of a detector assembly, the detector assembly comprising a linear array of detector elements, wherein the sensing region comprises at least a portion of the radiation, wherein the entrance pupil of the objective optic is coplanar with and in close proximity to an exit pupil of the projection optic, and wherein the radiation and the sensing region have respective axes that are collinear in a plane containing the exit pupil and entrance pupil;

Scanning both the radiation line and the sensing region over the scene using a scanning mirror along a second direction, the second direction being perpendicular to the first direction; and

signals output by the detector elements in response to the received radiation are processed to construct a three-dimensional (3D) map of objects in the scene.

16. The method of claim 15, wherein receiving radiation comprises aligning an array axis of the linear array along the first direction.

17. The method of claim 15, wherein projecting the radiation comprises applying a linear array of radiation sources to emit respective beams of radiation, and collecting and focusing the emitted beams to form the radiation.

18. The method of claim 15, wherein projecting the radiation comprises scanning a beam along the radiation in the first direction.

19. The method of claim 18, wherein scanning a beam comprises scanning the beam along the line at a first speed, and wherein scanning using the scanning mirror comprises scanning the line of radiation and the sensing region over the scene at a second speed, the second speed being slower than the first speed.

20. The method of any of claims 15-19, wherein scanning a beam of radiation comprises scanning pulses of radiation, and wherein signals output by the detector elements indicate respective times of flight of the pulses, and wherein processing the signals comprises constructing the 3D map in response to the times of flight.