WO2023141672A1

WO2023141672A1 - Spatial profiling systems and method

Info

Publication number: WO2023141672A1
Application number: PCT/AU2023/050040
Authority: WO
Inventors: Cibby Pulikkaseril; Yannick Lize; Matteo Staffaroni
Original assignee: Baraja Pty Ltd
Priority date: 2022-01-28
Filing date: 2023-01-24
Publication date: 2023-08-03

Abstract

Embodiments of a spatial profiling system for profiling an environment are described. The spatial profiling system includes a wavelength router configured to receive outgoing light from a light source, and optical components configured to receive and at least collimate the outgoing light into an environment. The wavelength router is mounted on a substrate coupled to one or more temperature control plates, each temperature control plate having a respective coefficient of thermal expansion that mitigates changes of direction of the collimated outgoing light into the environment due to thermal effects.

Description

Spatial profiling systems and method

Field of the invention

[0001] The present invention relates to the field of systems and methods for estimating a spatial profile of an environment.

Background

[0002] Spatial profiling refers to the three-dimensional mapping of an environment over a field of view of the environment. Each point or pixel in the field of view is associated with a distance to form a three-dimensional representation of the environment. Spatial profiles may be useful in identifying objects and/or obstacles in the environment, thereby facilitating automation of tasks.

[0003] One technique of spatial profiling involves sending light into an environment in a specific direction and detecting any light reflected back from that direction, for example, by a reflecting surface in the environment. This technique may be referred to as light detection and ranging, or LiDAR. The reflected light carries relevant information for determining the distance to the reflecting surface. The combination of the specific direction and the distance forms a point or pixel in the three-dimensional representation of the environment. The above steps may be repeated for multiple different directions to form other points or pixels of the three-dimensional representation, thereby estimating the spatial profile of the environment within a desired field of view.

[0004] Some known LiDAR systems operate using mechanical movement to cause light to be directed or scanned across a range of specific directions for range detection. Other systems rely on solid-state scanning, to reduce or avoid the need for mechanically moving parts. LiDAR systems with less mechanical moving parts may have particular application to vehicular LiDAR, for example autonomous or semi- autonomous vehicles.

[0005] Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art. Summary of the disclosure

[0006] In a first aspect of the present disclosure, there is provide a spatial profiling system for profiling an environment, system including: a wavelength router configured to receive outgoing light from a light source at a first port and route the light to a plurality of second ports, different to the first port, based on wavelength of the outgoing light, wherein the plurality of second ports are spatially separated; optical components configured to: receive and at least collimate the outgoing light after it has exited a port of the plurality of second ports; direct the collimated outgoing light into the environment; and receive return light including outgoing light reflected by a portion of the environment and direct the diffuse return light to the plurality of second ports of the wavelength router; wherein the wavelength router is mounted on a substrate coupled to one or more temperature control plates, each temperature control plate having a respective coefficient of thermal expansion that mitigates changes of direction of the collimated outgoing light into the environment due to thermal effects; and wherein the spatial profiling system is configured to direct the return light to detector circuitry for detecting the return light and generate a signal indicative of a spatial profile based on the detected return light.

[0007] The wavelength router may be an integrated circuit chip arrayed waveguide grating and wherein the plurality of second ports are located at an edge of the integrated circuit chip.

[0008] The spatial profiling system may include an optical circulator configured to receive the outgoing light from the light source and direct the light to the first port and to receive the return light from the first port and direct the light to the detector circuitry. [0009] The wavelength router may include at least one third port, different to the first port and the plurality of second ports, for receiving the return light. The detector circuitry may include a light detector for return light received via each of the first port and the at least one third port and wherein a processor generates the signal indicative of a spatial profile based on addition of signals corresponding to the detected return light at each of the first port and the at least one third port.

[0010] The optical components include a collimating lens to both collimate and angularly separate the outgoing light from the plurality of second ports.

[0011] The respective coefficient of thermal expansion that mitigates the changes match or substantially match the change transverse or longitudinal position of the wavelength router relative to a collimating element due to thermal effects.

[0012] The wavelength router and the optical components are configured to operate as a first beam director to direct the outgoing light over a first dimension of the environment and wherein the optical components further include a second beam director to direct the outgoing light over a second dimension, wherein the second dimension is or includes a component perpendicular to the first dimension.

[0013] The wavelength router may be an arrayed waveguide grating.

[0014] In a second aspect of the present disclosure, there is provide a bidirectional beam director for a spatial profiling system, the beam director including: a wavelength router configured to receive outgoing light from a light source at a first port and route the light to a plurality of second ports, different to the first port, based on wavelength of the outgoing light, wherein the plurality of second ports are spatially separated; optical components configured to: receive and at least collimate the outgoing light after it has exited a port of the plurality of second ports; direct the collimated outgoing light into the environment; and receive return light including outgoing light reflected by the environment and direct the return light to the plurality of second ports of the wavelength router; wherein the wavelength router is mounted on a substrate coupled to one or more temperature control plates, each temperature control plate having a respective coefficient of thermal expansion that mitigates changes of direction of the collimated outgoing light into the environment due to thermal effects.

[0015] The wavelength router includes at least one third port, different to the first port and the plurality of second ports, for receiving the return light.

[0016] The at least one third port is one of a plurality of third ports symmetrically arranged about the first port.

[0017] The optical components are configured to impart an angular separation of the outgoing light from the plurality of second ports.

[0018] The optical components include a collimating lens configured to both collimate and angularly separate the outgoing light from the plurality of second ports.

[0019] The wavelength router is an arrayed waveguide grating and wherein the plurality of second ports communicate the outgoing light to free space and receive the return light over free space.

[0020] The first port and at least one third port are each connected to single mode waveguide or optical fibre for receiving the return light.

[0021] The bidirectional beam director is configured to direct the collimated outgoing light over a first dimension and wherein the bidirectional beam director includes further optical components configured to receive the collimated outgoing light and direct it over a second dimension, wherein the second dimension is or includes a component perpendicular to the first dimension.

[0022] Also described are embodiments of a spatial profiling system for profiling an environment. The described spatial profiling system may spatially sample the portion of the environment. The spatial sampling may be utilised to address speckle in the reflected light. [0023] The system may include a wavelength router configured to receive outgoing light from a light source at a first port and route the light to a plurality of second ports, different to the first port, based on wavelength of the outgoing light, wherein the plurality of second ports are spatially separated.

[0024] The system may also include optical components configured to: receive and at least collimate the outgoing light after it has exited a port of the plurality of second ports; direct the collimated outgoing light into the environment; and receive diffuse return light including outgoing light reflected by a portion of the environment and direct the diffuse return light to the plurality of second ports of the wavelength router.

[0025] The wavelength router is configured to image, based on wavelength of the diffuse return light, the diffuse return light from the plurality of second ports to the first port and at least one third port, different to the first port and the plurality of second ports.

[0026] To detect the diffuse return light, the spatial profiling system may be configured to direct the diffuse return light from the first port and the at least one third port to detector circuitry and generate a signal indicative of a spatial profile based on a combination of the detected return light at each of the first port and the at least one third port.

[0027] In some embodiments the wavelength router is an integrated circuit chip arrayed waveguide grating and wherein the plurality of second ports are located at an edge of the integrated circuit chip.

[0028] In some embodiments the spatial profiling system includes an optical circulator configured to receive the outgoing light from the light source and direct the light to the first port and to receive the return light from the first port and direct the light to the detector circuitry. In some embodiments the spatial profiling system is configured to direct light from the at least one third port to the detector circuitry without passing through the optical circulator and in some embodiments the detector circuitry includes a light detector for return light received via each of the first port and the at least one third port and a processor generates the signal indicative of a spatial profile based on addition of the detected return light at each of the first port and the at least one third port. [0029] In some embodiments the wavelength router is mounted on a substrate coupled to one or more temperature control plates, each temperature control plate having a respective coefficient of thermal expansion that mitigates changes of direction of the collimated outgoing light into the environment due to thermal effects. In some embodiments the respective coefficient of thermal expansion that mitigates the changes match or substantially match the change transverse or longitudinal position of the wavelength router relative to a collimating element due to thermal effects.

[0030] In some embodiments the wavelength router and the optical components are configured to operate as a first beam director to direct the outgoing light over a first dimension of the environment and wherein the optical components further include a second beam director to direct the outgoing light over a second dimension, wherein the second dimension is or includes a component perpendicular to the first dimension. In some embodiments the second beam director is a mechanical beam director.

[0031] Embodiments of a bidirectional beam director for a spatial profiling system are described. The beam director includes a wavelength router configured to receive outgoing light from a light source at a first port and route the light to a plurality of second ports, different to the first port, based on wavelength of the outgoing light, wherein the plurality of second ports are spatially separated. The beam director also includes optical components configured to: receive and at least collimate the outgoing light after it has exited a port of the plurality of second ports; direct the collimated outgoing light into the environment; and receive return light including outgoing light reflected by the environment and direct the return light to the plurality of second ports of the wavelength router. The wavelength router is configured to direct the return light from the plurality of second ports to the first port and at least one third port, different to the first port and the plurality of second ports, wherein the direction of the return light from the plurality of second ports creates an interference pattern across the first port and at least one third port.

[0032] In some embodiments of the bidirectional beam director, the at least one third port includes a plurality of third ports.

[0033] In some embodiments of the bidirectional beam director the plurality of third ports are symmetrically arranged about the first port. [0034] In some embodiments of the bidirectional beam director, the optical components are configured to impart an angular separation of the outgoing light from the plurality of second ports. In some embodiments the optical components include a collimating lens configured to both collimate and angularly separate the outgoing light from the plurality of second ports.

[0035] In some embodiments of the bidirectional beam director, the wavelength router is an arrayed waveguide grating and wherein the plurality of second ports communicate the outgoing light to free space and receive the return light over free space.

[0036] In some embodiments of the bidirectional beam director, the first port and at least one third port are each connected to single mode waveguide or optical fibre for receiving the return light.

[0037] In some embodiments the bidirectional beam director is configured to direct the collimated outgoing light over a first dimension and wherein the bidirectional beam director includes further optical components configured to receive the collimated outgoing light and direct it over a second dimension, wherein the second dimension is or includes a component perpendicular to the first dimension.

[0038] Embodiments of a method of receiving and detecting diffuse light reflected by a portion of an environment for spatial profiling of the environment the described. The method includes, in a spatial profiling system: by optical components of the spatial profiling system, receiving and directing the diffuse light reflected by the environment to a plurality of first light ports, wherein the plurality of first light ports are spatially separated; creating an interference pattern of the diffuse light, by introducing a plurality of different delays to the diffuse light received at the plurality of first light ports to generate a plurality of return light signals, and interfering the return light signals; detecting, by light detectors, light across the interference pattern to thereby spatially sample the portion of the environment.

[0039] In some embodiments of the method, the spatial profiling system generates an estimate of the environment based on addition of the detected light at a plurality of positions across the interference pattern.

[0040] In some embodiments of the method, the process of detecting, by light detectors, light across the interference pattern includes receiving light at a plurality of spatially separated second light ports placed in the interference pattern, wherein the plurality of return light signals are formed by the light received by the plurality of spatially separated second light ports.

[0041] Embodiments of a method for spatial profiling an environment are described. The method includes spatially sampling portions of the environment by a bidirectional wavelength router and generating a signal indicative of a spatial profile based on the spatially sampled portions.

[0042] Embodiments of a method for spatial profiling an environment include: receiving outgoing light from a light source and causing spatial separation of the outgoing light based on wavelength; collimating and directing into the environment the spatially separated outgoing light; and receiving diffuse return light including reflected outgoing light and directing, based on wavelength the diffuse return light to a plurality of light detectors; and generating a signal indicative of a spatial profile based on a combination of the detected return light at each of the plurality of light detectors.

[0043] In some embodiments causing spatial separation of the outgoing light based on wavelength and directing, based on wavelength the diffuse return light to a plurality of light detectors is by a bidirectional wavelength router. In some embodiments the bidirectional wavelength router is in the form of an arrayed waveguide grating with a plurality of ports on an input slab and a plurality of output ports on an output slab.

[0044] Embodiments of a method of directing a beam to and from an environment for spatial profiling are described, the method including: receiving outgoing light from a light source at a first port of a wavelength router and routing the light to a plurality of second ports of the wavelength router, different to the first port, based on wavelength of the outgoing light, so as to cause spatial separation of the outgoing light based on wavelength; collimating and directing into the environment the outgoing light after it has exited a port of the plurality of second ports; receiving return light including outgoing light reflected by the environment and directing the return light to the plurality of second ports of the wavelength router; and directing the return light from the plurality of second ports to the first port and at least one third port, different to the first port and the plurality of second ports, wherein the direction of the return light from the plurality of second ports creates an interference pattern across the first port and at least one third port. [0045] In some embodiments, the method includes imparting an angular separation of the outgoing light after it has exited a port of the plurality of second ports.

[0046] In some embodiments, the spatially and angularly separated outgoing light is distributed across and first dimension and the method includes, by a beam director, distributing the spatially and angularly separated outgoing light across a second dimension, wherein the second dimension includes at least a component perpendicular to the first dimension.

[0047] As used herein, the terms “first”, “second” and so forth are used to distinguish one entity from another and are not used to indicate or require any particular sequencing, in time, position or otherwise. For example, “a first port and a second port” has the same meaning as “a port and another port”.

[0048] As used herein, a “port” is understood to mean an area, such as in the input slab or the output slab of the wavelength router, through which light passes, and does not necessarily require presence of a physical structure or component, such as where a port communicates to free space.

[0049] As used herein, “light” refers to electromagnetic radiation having optical frequencies, including far-infrared radiation, infrared radiation, visible radiation and ultraviolet radiation.

[0050] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

Brief description of the drawings

[0051] Figure 1 shows an arrangement of a spatial profiling system.

[0052] Figure 2 shows an arrangement of a light source, for the spatial profiling system of Figure 1 .

[0053] Figures 3 and 4 and 8 each show a beam director.

[0054] Figure 5 shows a wavelength router.

[0055] Figure 6 shows a portion of an integrated circuit chip. [0056] Figure 7 shows a wavelength router and transceiver circuitry.

Detailed description of the embodiments

[0057] Described herein are embodiments of an optical system, in particular a spatial profiling system, for directing light into an environment over one or two dimensions and detecting return light.

[0058] The one or two dimensions include a first dimension, for example along a y- axis which may be designated the vertical direction, and a second dimension, for example along a x-axis or horizontal direction. A spatial profile may be formed by determining, based on the return light, a distance along a z-axis or a depth direction for each of a plurality of x-y coordinates. The frame of reference used is not relevant - for example the one or two dimensions may be described using a polar coordinate system rather than a Cartesian coordinate system.

[0059] An example application of spatial profiling is to autonomous or semi- autonomous vehicles. For example, in the field of autonomous or semi-autonomous vehicles (land, air, water, or space), a spatial profiling system can estimate from the vehicle’s perspective, a spatial profile of the environment in which the vehicle is to navigate, including the distance to environmental objects, such as an obstacle or a target ahead.

[0060] A spatial profiling system using light may be referred to as a light detection and ranging (LiDAR) system. A LiDAR system estimates the spatial profile (e.g. the z- axis or depth at each of a plurality of x-y co-ordinates) of an environment based on light

[0061] Embodiments of the described optical system are capable of steering light based on one or more selected wavelength channels. While the following description refers to selecting a single wavelength channel (e.g. by tuning a wavelength-tunable laser), a person skilled in the art would appreciate that the description is also applicable, with minor modifications, for example optically coupling together two or more wavelength-tunable lasers, to select two or more wavelength channels.

[0062] LiDAR systems may be affected by spatial incoherence, spatial phase noise or speckle noise (called “speckle” herein). Speckle may arise, for example, from coherent outgoing light reflecting off a diffuse target. In order to reduce speckle noise, the outgoing light may be scanned over the targeting surface, which may be difficult to achieve in short acquisition windows (e.g. ~ 10MHz), as may be required to achieve a LiDAR system with a fast scanning speed. Speckle may also be reduced by using optical self-heterodyne detection of the reflected signal. In particular, the received light and the locally oscillated signal may be de-correlated by a differential optical path length such that the optical self-heterodyne detection is sufficiently incoherent for controllably reducing any speckles. In addition to speckle, the problems addressed by LiDAR system designers may further or alternatively include achieving reliable and accurate operation over a range of operating temperatures.

[0063] Figure 1 illustrates an arrangement of a spatial profiling system 100. As shown in the figure key, in the diagram electrical signals, carried by electrical conductors, are represented by a solid line connector, and optical signals, carried by guided optical connections, for example waveguides or optical fibres are represented by dashed lines. Light traversing free space, for direction into an environment for spatial profiling, is represented by a (bidirectional) striped arrow shape. Like connectors and arrow shapes are used in the figures subsequent to Figure 1 to illustrate like electrical and optical signals and a free space optical signal respectively. The blocks represent functional components of the spatial profiling system 100. It will be appreciated that functionality may be provided by distinct or integrated physical components. For example, a light source may include an integrated amplifier.

[0064] The spatial profiling system 100 includes a light source 101 for generating outgoing light. The spatial profiling system 100 may also include an optical amplifier 102 to amplify (providing gain to) light from the light source 101 . In some embodiments the optical amplifier 102 is an Erbium-doped fibre amplifier (EDFA) of one or more stages. In other embodiments one or more stages of a semiconductor optical amplifier (SOA), a booster optical amplifier (BOA), or a solid state amplifier (e.g. a Nd:YAG amplifier) may be used. In some embodiments, the optical amplifier 102 may be omitted.

[0065] The outgoing light from the optical amplifier 102 is received by transmission optics (Tx optics) for directing light to a beam director 104. The transmission optics may also condition the light, for example by including one or more collimators to form one or more beams of light. In some embodiments the transmission optics form a light transceiver 103, configured to both provide outgoing light to the beam director 104 and receive collected incoming light from the beam director 104. The light transceiver 103 may include one or more optical circulators, for example one or more of any of the optical circulators described in international patent application number

PCT/AU2018/051175, published as WO 2019/084610 A1 , the disclosure of which is incorporated herein in its entirely.

[0066] The beam director 104 functions to direct light over one or two dimensions into the environment to be estimated by the spatial estimation system 100. In some embodiments the beam director 104 includes bidirectional components, whereby both the outgoing light to the environment and incoming light from the environment traverse substantially the same path through the beam director 104, in opposite directions. Figure 1 represents this by the bidirectional arrow for the light traversing free space. If the outgoing light hits an object, at least part of the outgoing light may be reflected (represented in striped arrows), e.g. scattered, by the object back to the beam director

104 as incoming light. The beam director 104 directs the incoming light to the reception optics (e.g. the light transceiver 103), which collects the light and passes it to a light detector circuitry 105.

[0067] The light detector circuitry 105 includes one or more photodetectors. An example photodetector is an avalanche photodiode (APD). The light detector circuitry

105 generates incoming electrical signals that are representative of the detected incoming light. The light detector circuitry 105 may include a trans-impedance amplifier following the APD. An analog-to-digital converter 106 may convert analog incoming electrical signals to digital incoming electrical signals. The incoming digital signals are received and processed by a control system 107. The light source 101 and the amplifier 102 may be also controlled by the control system 107. In some embodiments the control system 107 controls aspects of operation of the other components in the system, for example the beam director 104 and/or the detector circuitry 105. The control system 107 may determine the profile of the environment based on its control or knowledge of the outgoing light and based on the incoming light signals. For example, some embodiments utilise a round trip time for light to determine the depth dimension.

[0068] Figure 2 illustrates an arrangement of the light source 101 . In this example, the light source 101 includes a wavelength-tunable light source, such as a wavelength- tunable laser diode, providing light of a tunable wavelength. The wavelength may be based on one or more electrical currents, for example the injection current into one of more wavelength tuning elements in a laser cavity, applied to the laser diode. The light source 101 accordingly is configured to provide outgoing light at a selected one or more of multiple selectable wavelength channels (each represented by its respective centre wavelength i, 2, ... N). In some embodiments the wavelength range of the wavelength-tunable light source is at least 20 nm, or at least 25 nm, or at least 30 nm, or at least 35 nm. The resolution of the wavelength-tunable light source (i.e. smallest wavelength step) is at most 0.2nm, preferably at most 0.1 nm, more preferably at most 0.05 nm and even more preferably at most 0.01 nm.

[0069] The light source 101 may include a single tunable laser or more than one tunable laser (or other types of lasers). The light source 101 may select one wavelength channel at a time or may simultaneously provide two or more different selected wavelength channels (i.e. channels with different centre wavelengths). In another example, the light source 101 may include a broadband light source and one or more tunable spectral filters to provide substantially continuous-wave (CW) light intensity at the selected wavelength(s). In another example, the light source 101 includes multiple laser diodes, each wavelength-tunable over a respective range and whose respective outputs are combined to form a single output. The respective outputs may be combined using a wavelength combiner, such as an optical splitter or an arrayed waveguide grating (AWG).

[0070] In one arrangement, the light source 101 is configured to provide the outgoing light to include at least one time-varying profile at the selected one or more of the multiple wavelength channels. The time-varying profile may be used, for example, in determining the round trip time of the light. In the example of Fig. 2, the light source 101 includes a modulator 204 for imparting a time-varying profile on the outgoing light. This modulation may be in addition to any wavelength tuning as herein before described. In other words, the modulation would be of light at the tuned wavelength. It will be appreciated that the tuned wavelength may refer to a center frequency or other measure of a wavelength channel that is generated. The time varying profile may, for example, be one or more of a variation in intensity, frequency, phase or code imparted to the outgoing light. In some embodiments, the light source 101 emits pulses of light, which pulses may include the time-varying profile. In other embodiments the difference between the presence of a pulse and the absence of a pulse is a time varying profile for use in determining the round trip time of light. In other embodiments, the outgoing light from the light source 101 has a different form, for example individual pulses for detecting the round trip time of the individual pulses instead of detecting the round trip time of a series of modulated pulses.

[0071] In one example, the modulator 204 is a semiconductor optical amplifier (SOA) or a Mach Zehnder modulator integrated on a laser diode of the light source 101 . The electrical current applied to the SOA may be varied over time to vary the amplification of the CW light produced by the laser over time, which in turn provide outgoing light with a time-varying intensity profile. In another example, the modulator 204 is an external modulator (such as a Mach Zehnder modulator or an external SOA modulator) to the laser diode. In another example, the modulator 204 is a phase modulator. Although Figure 2 illustrates that the modulator 204 is located before the optical amplifier 102, it will be appreciated that the modulator may be located either before or after the optical amplifier 102 in the outgoing light path. In yet another example, instead of including an integrated or external modulator, the light source 101 includes a laser having a gain medium into which an excitation electrical current is controllably injected for imparting a time-varying intensity profile on the outgoing light.

[0072] In some embodiments the light source 101 , optical amplifier 102 and a modulator are provided by a sampled-grating distributed Bragg reflector (SG-DBR) laser. By way of example, the SG-DBR laser may be controllable to provide 10 Gbps modulation, may operate across a 35 nm wavelength range and change from one wavelength to another in less than 100 nanoseconds. The wavelengths may have centre frequencies about 20 MHz or more apart.

[0073] The operation of the light source 101 , such as one or both of the wavelength- tunable laser 202 (e.g. its wavelength) and the modulator 204 (e.g. the modulating waveform), may be controlled by the control system 107. The control system may include an application specific device configured to perform the operations described herein, such as a configured programmable logic device, or a general purpose computing device with computer readable memory storing instructions to cause the computing device to perform the operations.

[0074] In the instance of an application specific device, the instructions and/or data for controlling operation of the processing unit may be in whole or in part implemented by firmware or hardware elements, including configured logic gates. In the instance of a general purpose computing device, the control system 107 may include, for example, a single computer processing device (e.g. a central processing unit, graphics processing unit, or other computational device), or may include a plurality of computer processing devices. The control system 107 may also include a communications bus in data communication with one or more machine readable storage (memory) devices which store instructions and/or data for controlling aspects of the operation of the processing unit. The memory devices may include system memory (e.g. a BIOS), volatile memory (e.g. random access memory), and non-volatile memory (e.g. one or more hard disk or solid state drives to provide non-transient storage). The operations for spatial profiling are generally controlled by instructions in the non-volatile memory and/or the volatile memory. In addition, the control system 107 includes one or more interfaces. The interfaces may include a control interface with the light source 101 and a communication interface with the light detector circuitry 105.

[0075] In some embodiments, light from the light source 101 is also provided to the detector circuitry 105 to provide a reference signal via a light path 110 from the light source 101 to the detector circuitry 105. For example, the light from the light source may first enter a sampler (e.g. a 90/10 fiber-optic coupler), where a majority portion (e.g. 90%) of the light is provided to the beam director and the remaining sample portion (e.g. 10%) of the light is provided instead to the detector circuitry. The detector circuitry may then be configured to inhibit detection of non-reflected light based on a difference in wavelength or modulation between the outgoing light and the non-reflected light. For example, the detection circuitry 105 includes one or more balanced detectors to coherently detect the reflected light mixed with reference light at the one or more balanced detectors.

[0076] In the embodiment of Figure 1 , the spatial profiling system 100 separates the functional components into two main physical units, i.e. an engine 108 and a sensor head 109. In one example, the engine 108 and the sensor head 109 are substantially collocated. The collocation allows these components to be compactly packaged within a single unit or in a single housing. In another example, the sensor head 109 is remote from the engine 108. In this variant, the engine 108 is optically coupled to the remote sensor head 109 via one or more guided optical connections, such as waveguides or optical fibres. The light transceiver 103 may be located in either the sensor head 109 as shown in Figure 1 or in the engine 108. In yet another variant, a spatial profiling system 100 may include a single engine 108 and multiple sensor heads. Each of the multiple sensor heads may be optically coupled to the engine 108 via respective guided optical connections. The multiple sensor heads may be placed at different locations and/or orientated with different fields of view.

[0077] Figure 3 illustrates a beam director 300, which may be an embodiment of the beam director 104 of Figure 1. Light, which may be light from the light source 101 via the transceiver 103, is provided over a guided optical connection, for example a single mode optical fibre or waveguide, to a port 301a of a wavelength router 302, which port serves as an input port to the wavelength router 302. As described later herein, in some embodiments the port is a bidirectional port, which is represented in Figure 3 by the bidirectional arrow.

[0078] The wavelength router 302 directs different wavelength channels from the port 301 a to a different one of ports 303-1 , 303-2 .... 303-M (collectively the ports 303). The routing is based wavelength and in some embodiments, M=N, so that each wavelength i, X2, ... AN is directed to a different one of the ports 303. However, variations are possible, for example with M<N and two or another integer number, of the wavelengths i, X2, ... AN being directed to one or more of, or each of, the ports 303. As described in more detail herein, the wavelength router 302 may be, or include, a modified form of one or more arrayed waveguide gratings (AWGs), with multiple ports on both the input and output slabs and with the output slab at the end of the chip. In Figure 3, the port 301 a is one of a plurality of ports, in this example three ports 301 a, 301 b and 301 c, collectively referred to as the ports 301 . As previously mentioned, a “port” is used herein to mean an area through which light passes and therefore each port may have corresponding physical structure defining an aperture or opening, or two or more ports, for example two or more of the ports 301 , 303, may be encompassed by physical structure that defines a single aperture or opening.

[0079] The ports 303 are arranged to cause or contribute to spatial separation or dispersion of the routed light across a dimension, called herein the wavelength dimension. This wavelength dimension may be, related to, or otherwise associated with the first dimension (e.g. a y-axis as shown in Figure 3, which may be the vertical direction having regard to an intended mounting orientation of the beam director 300). In Figure 3, the association arises from the arrangement of physical separation of the ports 303 to allow independent direction of the outgoing light along the y-axis. [0080] The routing of light across the wavelength dimension by the beam director 300 includes, in addition to the spatial separation, an angular separation. In some embodiments the angular separation is imparted by one or more dispersive or refractive optical components that receive light from the ports 303. An example of a dispersive or refractive component is a lens 304, diagrammatically shown in Figure 3. The lens 304 disperses or refracts the light from the ports 303 based on its wavelength to output from the beam director 303 the light at different angles. In other words, the lens 304 creates or increases the angular extent of the field of view of the system that the beam director 300 is a part of.

[0081] The lens 304 depicted in Figure 3 represents both embodiments with a single lens and embodiments including a lens system of two or more lenses. In other embodiments, other dispersive or refractive components are included in the beam director, in addition to or instead of one or more lenses, to receive and disperse the light from the ports 303. These other dispersive components may include, for example, gratings or prisms.

[0082] The lens 304 also represents an optical system that includes a collimator, for example a collimating lens, to form an outgoing beam of light at each wavelength channel. The lens 304 may be positioned relative to the ports 303 so that the ports appear as diverging sources at or substantially at the focal plane of the lens.

[0083] Figure 4 illustrates a beam director 400, which may be an embodiment of the beam director 104 of Figure 1. Light, which may be light from the light source 101 via the transceiver 103, is provided over a guided optical connection, for example a single mode optical fibre or waveguide, to a port 401 a of a wavelength router 402, which port serves as an input port to the wavelength router 402. As described later herein, in some embodiments the port is a bidirectional port, which is represented in Figure 4 by the bidirectional arrow. As described in more detail herein, the wavelength router 402 may be, or include, a modified form of one or more arrayed waveguide gratings (AWGs), with multiple ports on both the input and output slabs and with the output slab at the end of the chip. In Figure 4, the port 401 a is one of a plurality of ports, in this example three ports 401 a, 401 b and 401 c, collectively referred to as the ports 401 .

[0084] The wavelength router 402 directs different wavelength channels from the port

401 a to a different one of ports 403-1 , 403-2 .... 403-M (collectively the ports 403). The routing is based wavelength and in this embodiment, M<N. The wavelength router 402 groups the N wavelength channels into the M groups of channels. Each group may be formed by either neighbouring or in other words consecutive wavelength channels, or by non-neighbouring wavelength channels. In embodiments with non-neighbouring wavelength channels, each group of non-neighbouring wavelength channels includes non-consecutive wavelength channels. The M groups of non-neighbouring wavelength channels may be interleaved wavelength channels. In one example, where the N wavelength channels are designated by their centre wavelengths i, 2, ... N, the M groups of interleaved wavelength channels are { i, M+I , ... XN-M+I }, {X2, AM+2 ... X N-M +2}, ... and {XM, 2M, ... N}. That is, in this example, each group include evenly spaced wavelengths channel (in this case, every M wavelength channels), and all M groups have the same spacing. In another example, the non-neighbouring wavelength channels may be non-interleaved wavelength channels, but still spread almost from i to AN (e.g. { i, ... XN }, {X2, ... XN-2}, ... and {XM, ... N-M}). In either example, each group of interleaved wavelength channels spreads almost from i to N, the tunable range of the light source 102.

[0085] The ports 403 are arranged to cause or contribute to spatial separation or dispersion of the routed light across a dimension, called herein the wavelength dimension. This wavelength dimension may be, related to, or otherwise associated with the first dimension (e.g. a y-axis as shown in Figure 4, which may be the vertical direction having regard to an intended mounting orientation of the beam director 400). In Figure 4, the association arises from the arrangement of physical separation of the ports 403 to allow independent direction of the outgoing light along the y-axis.

[0086] The routing of light across the wavelength dimension by the beam director 400 includes, in addition to the spatial separation, an angular separation. In some embodiments the angular separation is imparted by one or more dispersive or refractive optical components that receive light from the ports 403. An example of a dispersive component is a lens 404, diagrammatically shown in Figure 4. The lens 404 disperses or refracts the light from the ports 403 based on its wavelength to output from the beam director 303 the light at different angles. In other words, the lens 404 creates or increases the angular extent of the field of view of the system that the beam director 400 is a part of. The lens 404 may direct different wavelength channels from one of the ports 403 in different directions, represented in Figure 4 by the double angularly offset arrows to the right of the lens 404.

[0087] The lens 404 depicted in Figure 4 represents both embodiments with a single lens and embodiments including a lens system of two or more lenses. In other embodiments, other dispersive or refractive components are included in the beam director, in addition to or instead of one or more lenses, to receive and disperse or refract the light from the ports 403. These other dispersive or refractive components may include, for example, gratings or prisms.

[0088] The lens 404 also represents an optical system that includes a collimator, for example a collimating lens, to form an outgoing beam of light at each wavelength channel. The lens 404 may be positioned relative to the ports 403 so that the ports appear as diverging sources at or substantially at the focal plane of the lens.

[0089] Example arrangements of components, including wavelength routers, for directing a beam over two dimensions are described in international patent application number PCT/AU2018/050961 , published as WO 2019/046895 A1 , the disclosure of which is incorporated herein in its entirely.

[0090] The beam director 300 and the beam director 400 are each configured to receive return light, including in particular outgoing light from the beam director 300, 400 that has been reflected (e.g. scattered) by the environment into which the outgoing light was directed. The return light traverses the lens 304, 404 and/or other dispersive components and is directed to the ports 303, 403. Some of the reflected light is directed to the same port 303, 403 from which it originated (e.g. reflected light at i is directed to port 303-1 , 403-1 ) and some of the reflected light is directed to one or more of the other ports 303-2 to 303-M or 403-2 to 403-M).

[0091] After being received by the ports 303, 403, the return light is directed, by the beam director 300, 400 to one or more of a plurality of the ports 301 , 401 . The return light is then passed, via a guided optical connection, for example a single mode optical fibre or waveguide, to detector circuitry for detection. For example the return light is passed to the detector circuitry 104 of the beam director 100 via the transceiver 103. The embodiments depicted in Figures 3 and 4 each have three ports for receiving this return light. In other embodiments there are two ports or four or more ports. It will be appreciated that the number of wavelength channels, N, may be substantially greater than the number of ports 301 , 401 , for example by at least a multiple of 10 (i.e. N/10 is greater than or equal to the number of ports 301 , 401 ), or at least a multiple of 100.

[0092] In some embodiments the total dispersion provided by the wavelength router 302 or the wavelength router 402 (in either single or cascaded form) is at least 1.0 pm/GHz over 35nm (for example 1530nm-1565nm). In other embodiments total dispersion provided by the wavelength router 302 or the wavelength router 402 (in either single or cascaded form) is at least 1 .5 pm/GHz, or at least 2.0 pm/GHz over 35nm ( for example 1530nm-1565nm).

[0093] Figure 5 shows an embodiment of a wavelength router 500, which may for example be the wavelength router 302 or the wavelength router 402. The wavelength router 500 includes or is an AWG integrated circuit chip 502. The AWG integrated circuit chip 502 may be fabricated, for example, in either SiO2 or Si N .

[0094] The ports 501 are provided on an input slab 505 of the AWG chip 502 and correspond to the ports 303 of the wavelength router 302 or the ports 403 of the wavelength router 402. Whilst three ports 501 are shown in the embodiment of Figure 5, as described previously herein, in other embodiments there may be two, or four or more ports 501 . The ports 501 in this example each connect to a respective single mode optical fibre 507. At least one of the single mode optical fibres 507 is operably connected to a light source to receive light therefrom, for example connected to the light source 101 via the transceiver 103 as shown in Figure 1. A plurality of the single mode optical fibres 507, up to all of the single mode optical fibres 507 are operably connected to a light detector, for example the detector circuitry 105 of Figure 1 , which connection may again be via the transceiver 103. In some embodiments a single mode fibre array 508 is provided at the interface of the ports 501 . The single mode fibre array 508 may, for example, be in the form of a v-groove array.

[0095] The ports 503 are provided on an output slab 506 of the AWG chip 502 and correspond to the ports 303-1 to 303-M of the wavelength router 302 or the ports 403-1 to 403-M of the wavelength router 402. The ports 503 communicate to free space, as indicated by the striped arrow shapes in Figure 5. The ports 503 are provided on the edge of the AWG integrated circuit chip 502. [0096] Between the input slab 505 and the output slab 506 is an array of waveguides 504 of different length, to thereby implement an arrayed waveguide grating, which outputs light of different wavelengths received at a port 501 at different ports 503. While the ports 503 may be distinct components in the output slab 506, in other embodiments the ports 503 are not physical components of the output slab 506. The illustrations of the ports 503 therefore denote areas through which light, having diffracted or otherwise propagated through the output slab 506, passes and is coupled to free space. The ports 503 may form a continuous or substantially continuous region, through which light of different wavelengths passes, in which case different wavelengths pass through different portions of the continuous or substantially continuous region. In Figure 5 the input slab 505 and output slab 506 are on adjacent sides of the AWG chip 502. In other embodiments the input slab 505 and output slab 506 are on the same side of the AWG chip or on opposite sides of the AWG chip. The AWG chip may be rectangular in shape or have different shape.

[0097] In some embodiments, the output slab 506 has a “folded” arrangement, where a reflecting interface (e.g. via total internal reflection) is included within the output slab to pass the light via the output slab multiple times. Embodiments with a folded arrangement may have particular application when a long focal length is required.

[0098] In some embodiments a beam director, for example the beam director 300 of Figure 3 includes a wavelength router formed from a plurality of cascaded wavelength router components. For example a first wavelength router component may receive light from a light source and route groups of, neighbouring or non-neighbouring, wavelength channels to each of a plurality of output ports. The groups of wavelength channels are then separated into sub-groups of, neighbouring or non-neighbouring, wavelength channels or into individual wavelength channels by one or more subsequent stages in the cascaded arrangement.

[0099] The first wavelength router may, for example, have the form of the wavelength router 402 of Figure 4, except that the ports 403 do not output to free space. Each port on the output side, for example each of the M ports 403 of the wavelength router 402, is connected to another (“second”) wavelength router component. The connection may be via guided optical connections, for example single mode optical fibres or waveguides. Each second wavelength router component may receive the group of wavelength channels from its respective port 403 and direct each wavelength channel to a different port, thereby implementing a two-level cascading arrangement. In other embodiments the second wavelength router component outputs sub-groups of wavelength channels, either to free space or to third level wavelength routers. In some embodiments at least the final stage of the cascading arrangement for outgoing light has wavelength routers with ports oriented in different directions, to achieve angular separation, either instead of or in addition to the use of dispersive components, such as the dispersive component(s) represented by lens 304 or the lens 404 in Figures 3 and 4. A collimator may still be provided for the output ports.

[0100] Each of the wavelength routers in the final stage of such a cascaded arrangement may, for example, be in the form of an arrayed waveguide grating integrated circuit chip with an output slab with ports at the edge of the chip, for example the arrayed waveguide grating integrated circuit chip of Figure 5. Earlier stages may also be in the form of arrayed waveguide grating integrated circuit chip, but the earlier stages may have ports that output light to a waveguide or optical fibre for passing to the next stage. It will be appreciated that for these earlier stages the output slab need not have ports at the edge of the chip and may instead have ports internal to the chip, which may connect to internal waveguides. In some embodiments, two or more levels, up to all of the levels of the cascaded arrangement of wavelength routers may be AWGs fabricated on a single integrated circuit chip.

[0101] In some embodiments the first-stage in the cascaded arrangement is a wavelength router, such as a cyclical AWG, which has a free-spectral range (FSR) multiple times smaller than the operating range of the light source laser providing light to the wavelength router. The second-stage AWGs have a FSR that is greater than the operating range of the laser and therefore each act like an AWG in a single-AWG embodiment.

[0102] An example of the first-stage in the cascaded arrangement is an AWG, at a free spectral range (FSR) of 100GHz or 0.8nm@1550nm. Light separated by the FSR is routed from its input port to the same one of the output ports. So, referring to the example of the wavelength router 402 shown in Figure 4, light at i=1550nm, X9=1550.8nm, i7=1551.6nm and so forth is routed to port 403-1 , and light at X2=1550.1 nm, Xio=155O.9nm, i8=1551.7nm and so forth is routed to port 403-2, and this arrangement continues through the ports. For example light at X8=1550.7nm, i6=1551 ,5nm, X24=1552.3nm and so forth is routed to the eighth port of the M ports.

[0103] Because the second-stage AWGs receive cyclical wavelength channels, for example a first, second-stage AWG receives i, g, 17 and so forth and a second, second-stage AWG receives i, 10, is and so forth, the wavelength outputs are interleaved, rather than being monotonic. The interleaving of the outputs may be accommodated by the control system, for example the control system 107, which can tune the wavelength of the light source, for example the light source 101 , to output wavelength channels in any required order.

[0104] In some embodiments, the guided optical connections, such as optical waveguides or fibres 507, are angularly arranged relative to the input slab 505 to facilitate continuity or substantial continuity of light across the ports 503 in the output slab 506.

[0105] Figure 6 diagrammatically illustrates an embodiment of part of an integrated circuit chip, including a wavelength router 600 and a refractive element 601 , such as a focussing or defocussing element, fabricated on a substrate 602. The wavelength router 600 includes at least a first port (e.g. an input port) and multiple second ports (e.g. output ports) that are spatially offset. The wavelength router 600 is configured to selectively direct outgoing light, based on wavelength, from the first port to one or more of multiple second ports. The wavelength router 600 may be further configured to direct incoming light (e.g. light returned from the environment), based on wavelength, from the one or more of multiple second ports to the first port. The wavelength router 600 may be further configured to direct the incoming light to one or more third ports, spatially offset from at least one of the multiple second ports. The wavelength router 600 may, for example be a dispersive element, such as an AWG or a diffraction grating. Alternatively, the wavelength router 302, the wavelength router 402 or the wavelength router 500 described herein. Similarly, the dispersive or refractive element element 601 may correspond to the lens 304 or the lens 404 of Figures 3 and 4 respectively. For example, the dispersive or refractive element element 601 may be a collimating lens or a collimating lens system of two or more lenses. Based on a relative location of the wavelength router 600 and the dispersive or refractive element 601 , light emitted from different ones of the spatially offset second ports is angularly separated into different directions. The relative location may include either or both of a relative longitudinal position (e.g. along an optic axis of the dispersive or refractive element 601 ) and a relative transverse position (e.g. orthogonal to the optic axis of the dispersive or refractive element 601 ). The substrate 602 fixes the relative location of the wavelength router 600 and the dispersive or refractive element 601. For example, the relative location may be such that the ports of the wavelength router 600 that direct light to the dispersive or refractive element 601 appear as diverging sources at or substantially at a focal plane of the dispersive or refractive element 601 .

[0106] The integrated circuit chip includes a first temperature control plate 603 coupled to, for example by being located between, the wavelength router 600 and the substrate 602. The first temperature control plate 603 has a thermal coefficient of expansion selected to mitigate thermal effects on the transverse position of the wavelength router 600 relative to, for example, the optic axis of the dispersive or refractive element 601 . In particular, the material of the temperature control plate 603 is selected to have a thermal coefficient of expansion that raises or lowers the wavelength router 600, relative to the dispersive or refractive element 601 . The expansion raises or lowers the wavelength router 600 by an extent that fully or partially compensates for changes in direction of the light of one or more wavelength channels output from the beam director, in the wavelength dimension of the beam director, due to position changes, relative to the dispersive or refractive element 601 , of the wavelength router 600 that arise due to thermal effects.

[0107] The integrated circuit chip also includes a second temperature control plate 604, in the substrate 602 coupled to, for example by being located between, the wavelength router 600 and the dispersive or refractive element 601 . The second temperature control plate 604 has a thermal coefficient of expansion selected to mitigate thermal effects on the longitudinal position of the wavelength router 600 relative to, for example the focal plane of, the dispersive or refractive element 601 . In particular, the material of the temperature control plate 603 is selected to have a thermal coefficient of expansion so that it expands and contracts with temperature so as to match or substantially match the change in longitudinal position of the wavelength router 600 relative to, for example the focal plane of, the collimating element 601 due to thermal effects. [0108] Figure 7 shows a wavelength router 700 and transceiver circuitry 701 . The wavelength router 700 may, for example, be the wavelength router 302, the wavelength router 402 or the wavelength router 500 described herein. The wavelength router 700 may be an AWG chip, of the form described with reference to Figure 5. The AWG chip of Figure 7 has an irregular pentagon shape and includes an input slab 702 with associated ports, including port 704 and six other ports internal to the AWG chip. The AWG chip includes an output slab 703 with output ports at the edge of the AWG chip.

[0109] The transceiver circuitry 701 may, for example, be the transceiver 103 described with reference to Figure 1 . The transceiver circuitry 701 includes an optical circulator 706 and includes guided optical connections, such as optical waveguides or fibres, for communicating optical signals. As Figure 7 shows the connector for the optical signal, the lines are solid lines, rather than dashed lines representing the optical signal carried by the guided optical connection.

[0110] One of the guided optical connections of the transceiver circuitry 701 , for example a waveguide 705 (which may be an optical fibre), is optically connected to receive outgoing light, for example outgoing light from a tunable light source, which may be the light source 101 . As described herein the outgoing light may be tuned to include a range of different wavelength channels I- N. The light source may continuously change wavelength between two or more of the wavelength channels or may include a step change in wavelength between two or more of the wavelength channels.

[0111] The waveguide 705 provides the outgoing light to an input port of the optical circulator 706. The optical circulator 706 outputs the outgoing light at a port connected to a guided optical connection, for example an optical fibre 707. The optical fibre 707 is a single mode optical fibre. Alternatively the optical fibre 707 may be another form of single mode waveguide. The port connected to the optical fibre 707 is a bidirectional port of the optical circulator. The optical fibre 707 connects the bidirectional port with the port 704 of the input slab 702 of the wavelength router 700.

[0112] In some embodiments the port 704 is the centre port or a central port of the input slab 704, like the bidirectional port in the wavelength routers 302 and 402 is the central port. The other ports are placed symmetrically around the port 704. Figure 7 shows an embodiment in which there are six return-only fibres, for generating ICR-2 to ICR-7. More return-only fibres means the system is less susceptible to speckle, but at a cost of more channels/receivers/ADCs/processing.

[0113] The outgoing light received by the wavelength router 700 at port 704 of the input slab 702 is passed to the output slab 703 via a waveguide array 708. The outgoing light is directed into free space from a port of the output slab 703, which port depends on the wavelength of the outgoing light. Prior to being directed into an environment for spatial profiling purposes, the outgoing light may be received and conditioned and/or directed by further optical components (not shown in Figure 7), for example a collimating lens and/or one or more other diffracting elements as described herein.

[0114] A portion of the outgoing light may be received at the output slab 703, due to be being reflected by the environment and directed by the collimating lens or other optical components to the ports of the output slab 703. The light received at the ports of the output slab 703 may be received together with environmental light and may be received together with interfering light signals. The collection of light received will be referred to as return light.

[0115] The return light received by the wavelength router 700 at each or any output port of the output slab 703 is passed back to the input slab 702 via the waveguide array 708. In general, a portion of the light received at each or any port is communicated over respective waveguides in the waveguide array. The return light is then passed to the input ports of the input slab, including a portion to the port 704 and a portion to one or more of the other ports. In ideal scenarios without the effects of speckle, propagation of reflected light in the return light through the wavelength router 700 would result in the reflected light being imaged to where light originated from (i.e. the central port 704). In practical scenarios, the reflected light in the return light is speckled (diffuse), and propagation of reflected light in the return light through the wavelength router 700 results in the reflected light being imaged as a diffused field at the input slab 702. Some of the reflected light is received at the central port 704 and associated optical fibre 707. However, some of the reflected light is also received at the adjacent M input ports and waveguides. Across the central port 704 and adjacent M input ports an image 705 is formed, the image formed by interfering signals in the input slab 702. The image 705 may therefore be described as an interference pattern. In this way, the target (i.e. the part of the environment reflecting the outgoing light), is spatially sampled, which can be utilised to mitigate speckle effects. In particular, by having single mode fibres/waveguides connected to each of a plurality of the ports of the input slab 702, a plurality of return optical signals are generated, which are labelled integrated-circuit return (ICR) 1 through to 7 (i.e. ICR-1 to ICR-7) in the example of Figure 7. Less or more return optical signals may be generated and less or more return optical signals may be used to mitigate speckle effects.

[0116] The mitigation of speckle effects using embodiments described herein may be achieved without using standalone despeckling optics. Examples of standalone despeckling optics include a photonic lantern, a mode demultiplexer and mode couplers. In other words, a spatial estimation system may not include these standalone despeckling optics.

[0117] In some embodiments, each of ICR-1 to ICR-7 is converted to an electrical signal, for example by the detector circuitry 105, which may be converted to a digital signal, for example by ADC 106. Signal processing circuitry, for example the control system 107 may then combine, for example by performing addition of, the digital signals representing the detected ICR-1 to ICR-7, to reduce speckle effects. In one embodiment, the addition may be performed in a weighted manner, for example placing more weight on one or more digital signals (e.g. the signal corresponding to the central port 704) than the others.

[0118] The embodiments described so far have included a beam director for directing light over a (first) dimension, which has been called the wavelength dimension. The beam director may include mechanisms to direct light over another (second) dimension, which dimension is or at least includes a component perpendicular to the first dimension. The mechanism may also operate based on wavelength, so as to provide a second wavelength dimension. Alternatively the mechanism may operate by mechanical movement, so as to provide a mechanical dimension.

[0119] Figure 8 shows an example of a beam director 800, which includes the beam director 300 described with reference to Figure 3 (the description of which is not repeated for succinctness) and a mechanical beam director 801 , for example a physically rotating reflector (e.g. mirror) or rotating prism arrangement. The mechanical beam director receives the outgoing light from the lens 304, which has been dispersed across the y-dimension or vertical dimension, which may be called the wavelength dimension, and steers it across the x-dimension or horizontal dimension, which may be called the mechanical dimension. Viewed from an arbitrary image plane 802, when using a pulsed light source, the mechanical dimension creates a plurality of rows of image points, including a row 803 for light at i and including a row 804 for light at N. The columns in the image plane 802 are formed by the wavelength dispersion. In practice the dispersion across the wavelength dimension may occur at a much faster cycle rate than the cycle rate for steering across the mechanical dimension.

[0120] A beam director which includes two wavelength dimensions may be formed by replacing the beam director 300 with the beam director 400 and replacing the mechanical beam director 801 with a dispersive component. The dispersive component may for example be or include one or more diffraction gratings, to direct each group of wavelength channels from each port 403 of the beam director 400 across the second wavelength dimension.

[0121] Placing ports of the output slab of an AWG chip at the edge of the chip, so that the ports communicate to free-space, allows for continuous steering of wavelength over the slab, similar to a free space diffraction grating. “Continuous” here means continuity of beam steering over at least a certain wavelength range or ranges, and does not necessarily mean continuity over the entire operating wavelength range of the laser/LiDAR unit. For example, beam steering can be continuous from i to 2, but non- continuous from X2 to 3, whether or not it is continuous from X3 to 4, for an illustrative operating wavelength range of i to X4.

[0122] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

CLAIMS A spatial profiling system for profiling an environment, system including: a wavelength router configured to receive outgoing light from a light source at a first port and route the light to a plurality of second ports, different to the first port, based on wavelength of the outgoing light, wherein the plurality of second ports are spatially separated; optical components configured to: receive and at least collimate the outgoing light after it has exited a port of the plurality of second ports; direct the collimated outgoing light into the environment; and receive return light including outgoing light reflected by a portion of the environment and direct the diffuse return light to the plurality of second ports of the wavelength router; wherein the wavelength router is mounted on a substrate coupled to one or more temperature control plates, each temperature control plate having a respective coefficient of thermal expansion that mitigates changes of direction of the collimated outgoing light into the environment due to thermal effects; and wherein the spatial profiling system is configured to direct the return light to detector circuitry for detecting the return light and generate a signal indicative of a spatial profile based on the detected return light. The spatial profiling system of claim 1 , wherein the wavelength router is an integrated circuit chip arrayed waveguide grating and wherein the plurality of second ports are located at an edge of the integrated circuit chip. The spatial profiling system of claim 1 , including an optical circulator configured to receive the outgoing light from the light source and direct the light to the first port and to receive the return light from the first port and direct the light to the detector circuitry. The spatial profiling system of claim 3, wherein the wavelength router includes at least one third port, different to the first port and the plurality of second ports, for receiving the return light. The spatial profiling system of claim 4, wherein the detector circuitry includes a light detector for return light received via each of the first port and the at least one third port and wherein a processor generates the signal indicative of a spatial profile based on addition of signals corresponding to the detected return light at each of the first port and the at least one third port. The spatial profiling system of claim 1 , wherein the optical components include a collimating lens to both collimate and angularly separate the outgoing light from the plurality of second ports. The spatial profiling system of claim 1 , wherein the respective coefficient of thermal expansion that mitigates the changes match or substantially match the change transverse or longitudinal position of the wavelength router relative to a collimating element due to thermal effects. The spatial profiling system of claim 1 , wherein the wavelength router and the optical components are configured to operate as a first beam director to direct the outgoing light over a first dimension of the environment and wherein the optical components further include a second beam director to direct the outgoing light over a second dimension, wherein the second dimension is or includes a component perpendicular to the first dimension. The spatial profiling system of claim 8, wherein the arrayed waveguide grating and wherein the plurality of second ports communicate the outgoing light to free space and receive the return light over free space. A bidirectional beam director for a spatial profiling system, the beam director including: a wavelength router configured to receive outgoing light from a light source at a first port and route the light to a plurality of second ports, different to the first port, based on wavelength of the outgoing light, wherein the plurality of second ports are spatially separated; optical components configured to: receive and at least collimate the outgoing light after it has exited a port of the plurality of second ports; direct the collimated outgoing light into the environment; and receive return light including outgoing light reflected by the environment and direct the return light to the plurality of second ports of the wavelength router; wherein the wavelength router is mounted on a substrate coupled to one or more temperature control plates, each temperature control plate having a respective coefficient of thermal expansion that mitigates changes of direction of the collimated outgoing light into the environment due to thermal effects. The bidirectional beam director of claim 10, wherein the wavelength router includes at least one third port, different to the first port and the plurality of second ports, for receiving the return light. The bidirectional beam director of claim 11 , wherein the at least one third port is one of a plurality of third ports symmetrically arranged about the first port. The bidirectional beam director of any one of claims 10 to 12, wherein the optical components are configured to impart an angular separation of the outgoing light from the plurality of second ports. The bidirectional beam director of claim 13, wherein the optical components include a collimating lens configured to both collimate and angularly separate the outgoing light from the plurality of second ports. The bidirectional beam director of claim 10, wherein the wavelength router is an arrayed waveguide grating and wherein the plurality of second ports communicate the outgoing light to free space and receive the return light over free space. The bidirectional beam director of claim 11 , wherein the first port and at least one third port are each connected to single mode waveguide or optical fibre for receiving the return light. The bidirectional beam director of claim 10, wherein the bidirectional beam director is configured to direct the collimated outgoing light over a first dimension and wherein the bidirectional beam director includes further optical components configured to receive the collimated outgoing light and direct it over a second dimension, wherein the second dimension is or includes a component perpendicular to the first dimension.