Beam control systems and methods for optical power beaming

Abstract

A power beaming system comprising a power transmitter configured to generate an outgoing optical beam, wherein the outgoing optical beam include a safety beam comprising light at a first wavelength, and a power beam comprising light at a second wavelength; and a transmitter controller configured to control operation of the power transmitter to control generation of the safety beam and generation of the power beam, such as to direct the outgoing optical beam towards a power receiver; implement one or more operational subsystems and a safety subsystem, wherein the one or more operational subsystem is interfaced with the safety subsystem; and wherein the safety subsystem is configured to monitor the one or more operational outputs of the one or more operational subsystems; and control operation of the power beam such that the power beam is disabled when the current operational status is determined to include at least one blocking status.

Description

BEAM CONTROL SYSTEMS AND METHODS FOR OPTICAL POWER BEAMINGCROSS-REFERENCES

[0001] The present application claims convention priority to Australian patent application no. 2024901138 filed on 23 April 2024, entitled “SAFETY SYSTEMS AND METHODS FOR OPTICAL POWER BEAMING”, Australian patent application no. 2025900301 filed on 4 February 2025, entitled “SAFETY SYSTEMS AND METHODS FOR OPTICAL POWER BEAMING”, and Australian patent application no. 2025900408 filed on 14 February 2025, entitled “SAFETY SYSTEMS AND METHODS FOR OPTICAL POWER BEAMING”, the entire disclosure of each of which is incorporated herein by reference.

[0002] The present application is related to the PCT applications entitled “STEERING SY STEMS AND METHODS FOR OPTICAL POWER BEAMING”, “SAFETY SYSTEMS AND METHODS FOR OPTICAL POWER BEAMING”, “INTERLOCK SYSTEMS AND METHODS FOR OPTICAL POWER BEAMING”, each filed in the name of the present applicant and sharing the same filing date as the present application, and each also claiming convention priority to Australian patent application numbers 2024901138, 2025900301, and 2025900408. The entire disclosure of each ofthese related PCT applications is incorporated herein by reference. Reference made herein to the “Applicant’s co-pending applications” corresponds to the disclosures of the related PCT applications.TECHNICAL FIELD

[0003] The invention generally relates to systems and methods for power beaming via free-space optical means, and in particular, optical power beaming systems and methods, including startup procedures, with safety precautions.BACKGROUND TO THE INVENTION

[0004] The knowledge described in this section is known to the inventors or Applicant. However, unless otherwise indicated, it should not be taken that any of the described knowledge in this section qualify as prior art or common general knowledge, in any jurisdiction, merely by virtue of their inclusion in this section, or that the described knowledge is known to a person of ordinary skill in the art.

[0005] In optical power beaming (i.e. power delivery via frees-space optical means), a harmfully high amount of optical power is typically found in the power delivery optical beam that propagates unguided in air / free-space. Safety considerations, such as eye safety, injury to wildlife, stray reflections, or otherwise entry of any intervening obstacles into the beam path, can limit the deployment of optical power beaming as a safe power transfer option.

[0006] In optical power beaming, it is known to send a radio-frequency (RF) signal, from the power receiver to the power transmitter, to provide feedback to the power transmitter regarding status of power receipt. The RF feedback can be indicative of the level of received power, such that the power transmitter responsive to receiving the feedback can determine whether it is to continue (or stop) power 2 delivery, for example, based on the received power matching (or mismatching) the transmitted power, taking into account attenuation. However, RF techniques can be limited in range. Further, the broadcasting nature of RF techniques can be susceptible to interception and thus hacking by malicious actors.

[0007] There is therefore a need for improving safety considerations of optical power beaming associated with entry of obstacles into the optical beam path, and / or at least provide an alternative to optical power beaming systems and methods.BRIEF SUMMARY OF THE DISCLOSURE

[0008] Embodiments of the present disclosure makes use of transmission of light with dual wavelengths, with one wavelength used for power delivery to a power receiver and another wavelength used for safety piloting from, and / or safety interlock at, a power transmitter. Safety piloting may involve transmitting, for piloting purposes, light at a first wavelength (e.g. eye-safe wavelength), and then transmitting, for power delivery purposes, light at a second wavelength (e.g. power delivery wavelength) upon receipt of return light at the first wavelength back at the transmitter. Safety interlock may involve cessation of light transmission at the second wavelength, responsive to reduction or non-receipt of return light at the first wavelength back at the transmitter.

[0009] According to an aspect of the present disclosure, there is provided a power beaming system comprising: a power transmitter configured to controllably generate an outgoing optical beam, wherein the outgoing optical beam is controlled such as to include either or both of: a safety beam component comprising light at a first wavelength, and a power beam component comprising light at a second wavelength; and a transmitter controller configured to: control operation of the power transmitter such as to control generation of the safety beam component and generation the power beam component, such as tocontrollably direct the outgoing optical beam towards a target airborne power receiver; implement one or more operational subsystems and a safety subsystem, wherein the, or each, operational subsystem is operably interfaced with the safety subsystem, wherein the, or each, operational subsystem is configured to generate at least one operational output, and wherein the safety subsystem is configured to: monitor the one or more operational outputs of the one or more operational subsystems; determine a current operational status in dependence on the current one or more operational outputs; and control operation of the power beam such that the power beam is disabled when the current operational status is determined to include at least one blocking status.

[0010] Optionally, at least one operational subsystem is configured to generate an associated operational output dependent upon data received from the power receiver via a wireless data channel. The system may comprise a flight telemetry operational subsystem configured to receive flight telemetry data from the power receiver via the wireless data channel, and to generate an associated flight telemetry operational output comprising the flight telemetry data. The safety subsystem may be configured to determine a blocking status in response to determining, from the flight telemetry operational output, that the flight telemetry data indicates that the current flight of the power receiver fails to satisfy a predefined flight requirement. The system may comprise an auxiliary telemetry operational subsystem configured to receive auxiliary telemetry data from the power receiver via the wireless data channel, and to generate an associated auxiliary telemetry operational output comprising the auxiliary telemetry data. The auxiliary telemetry data comprises temperature measurements, electrical supply measurements, etc. The safety subsystem may be configured to determine a blocking status in response to determining, from the auxiliary telemetry operational output, that the auxiliary telemetry data indicates that at least one current measurement of the power receiver is indicative of a predefined fault condition.

[0011] Optionally, at least one operational subsystem is an active operational subsystem configured to generate an associated operational output based on active measurements made at the power transmitter, wherein the active measurements are of an interaction between the outgoing optical beam and the power receiver. The system may comprise at least one active operational subsystem in which the associated active operational output is based on measurement made at the power transmitter of an interaction between the safety beam and the power receiver. The safety subsystem may be configured to determine a blocking status in response to: determining a non-alignment condition between the safety beam and the power receiver; and / or determining that the current measurement of the interaction between the safety beam and the power receiver is indicative of a threshold likelihood of a foreign object interacting with the safety beam.

[0012] Optionally, at least one operational subsystem is a passive operational subsystem configured to generate an associated passive operational output based on passive measurements made at the power transmitter of the power receiver. The system may comprise an imaging arrangement, and the system may comprise at least one passive operational subsystem configured to generate an associated passive operational output utilising images of the power receiver captured by the imaging arrangement. The safety subsystem may be configured to determine a blocking status in response to determining, from the images captured by the imaging arrangement, a fault flight condition of the power receiver.

[0013] Optionally, the safety subsystem is configured to: determine one or more combined statuses, wherein each combined status is associated with two or more operational outputs and is determined, at least in part, according to a comparison between its associated operational outputs, wherein the current control status is determined by reference to the current one or more operational outputs and the current one or more combined statuses. For at least one combined status, a blocking status may be determined when at least one of its associated operational outputs indicates a first flight condition of the power receiver and at least one other of its associated operational outputs indicates a second flight condition which may be determined, by the safety subsystem, to be inconsistent with the first flight condition.

[0014] Optionally, the transmitter controller is configured to implement a startup procedure before activating the power beam, wherein the startup procedure comprises an initialisation routine and a sequence of two or more subsequent startup routines, and wherein the safety subsystem is configured to: during the initialisation routine, determine that the current operational status comprises an initial blocking status before proceeding to a first subsequent startup routine; for each subsequent startup routine: identify at least one associated operational output of the one or more operational outputs, monitor said at least one associated operational output during the subsequent startup, and determine either a pass condition or fail condition for the subsequent startup routine based, at least in part, on the monitoring of said at least one associated operational output; and determine removal of the initial blocking status only upon determining a pass condition for every one of the two or more subsequent startup routines. Each subsequent startup routine after a first subsequent startup routine may be initiated only upon determining a pass condition of a directly preceding subsequent startup routine in the sequence. For at least one subsequent startup routine, the safety subsystem may be configured to determine either the pass condition or fail condition for the subsequent startup routine based, at least in part, on at least one combined status. The initialisation routine may comprise determining, via wireless data communication between the power transmitter and the power receiver, a compatibility of the power receiver for receiving the optical beam.

[0015] The system may comprise the power receiver. The power receiver may be affixed to an airborne vehicle.

[0016] According to another aspect of the present disclosure, there is provided a power beaming system including: a power transmitter configured to controllably transmit an outgoing optical beam, the outgoing optical beam including a safety beam comprising light at a first wavelength and, in dependence on a control condition, a power beam comprising light at a second wavelength, distinct from the first wavelength; a power receiver configured to receive the outgoing optical beam, the power receiver including a wavelength discriminator configured to: return the safety beam for receipt by the power transmitter; and accept the power beam for optical-to-electrical power conversion; and wherein the power transmitter is controlled, at least in part, by a transmitter controller, wherein the transmitter controller is configured to control transmission of the optical beam based on the returned safety beam received at the power transmitter.

[0017] Optionally, the wavelength discriminator includes a dichroic retroreflector. The dichroic retroreflector may be configured to: retroreflect substantially the safety beam back to the power transmitter, and to pass through substantially the power beam for optical-to-electrical power conversion at the power receiver. The dichroic retroreflector may include a dichroic comer cube reflector.

[0018] Optionally, the transmitter controller is configured to cease, or at least partially cease, transmission of the power beam by the power transmitter based on determination of the existence of at least one blocking status. At least one blocking status may be determined in case wherein a measurement made at the power transmitter of the returned safety beam is determined to indicate a first predetermined condition indicative of a likelihood of a foreign object present between the power transmitter and the power receiver. The first predetermined condition may include defined changes in a property of the returned safety beam received at the power transmitter.

[0019] Optionally, control of transmission of the outgoing optical beam includes commencement of transmission of the power beam based on the transmitter controller determining a second predetermined condition. The second predetermined condition may include determining a maximal measurement of the returned safety beam at the power transmitter.

[0020] Optionally, the system further includes, at the power receiver, a photovoltaic assembly configured to convert optical power contained in the power beam to electrical power.

[0021] Optionally, the safety beam is axially aligned with the power beam, the safety beam having a larger beam diameter than the power beam along at least a portion of the axially aligned beams. The safetybeam may have a larger beam diameter than the power beam along all portion of the axially aligned beams, at least between the power transmitter and the power receiver.

[0022] Optionally, the system comprises a multi-wavelength laser configured to provide both the safety beam and the power beam.

[0023] Optionally, the system comprises a safety beam light source and a separate power beam light source at the power transmitter, and an optical combiner at the power transmitter configured to combine the safety beam as emitted by the safety beam light source and the power beam as emitted by the power beam light source to provide the outgoing optical beam. The optical combiner may include at least one of the following: a beam splitter, dichroic mirror, a wavelength-division multiplexer.

[0024] Optionally, the system further includes beam shaping optics at the power transmitter for beam shaping the optical beam. The beam shaping optics may include a first set of optics for beam shaping the safety beam, and / or a second set of optics for beam shaping the power beam. The safety beam light source may comprise a first laser source and the power beam light source may comprise a second laser source. The first wavelength may be within an eye-safe wavelength band and the second wavelength may be within an atmospherically least absorptive or at least sufficiently low absorptive wavelength band.

[0025] Optionally, the power transmitter is a first power transmitter of multiple power transmitters, and wherein the transmitter controller is configured to control operation of both the first power transmitter and a second power transmitter of the multiple power transmitters.

[0026] Optionally, the transmitter controller is configured to: control operation of the power transmitter such as to control transmission of the safety beam component and the power beam component, such as to controllably direct the outgoing optical beam towards a target airborne power receiver; implement one or more operational subsystems and a safety subsystem, wherein the, or each, operational subsystem is operably interfaced with the safety subsystem, wherein the, or each, operational subsystem is configured to generate at least one operational output, and wherein the safety subsystem is configured to: monitor the one or more operational outputs of the one or more operational subsystems; determine a current operational status in dependence on the current one or more operational outputs, wherein the current operational status selected from at least one blocking and at least one nonblocking; and control operation of the power beam such that the power beam is disabled when the current operational status is determined to be a blocking status.

[0027] Optionally, at least two operational statuses are transmitter operational statuses, wherein each transmitter operational status is generated without dependence on data received from the power receiver. The transmitter controller may be configured to: implement a redundancy subsystem configured to: monitor at least one combined status being a transmitter-only combined status being a combined status based upon a comparison between two or more transmitter operational statuses; determine a blocking status in response to determining a discrepancy between at least a first transmitter operational status and a second transmitter operational status.

[0028] According to another aspect of the present disclosure, there is provided a power transmitter for use in a power beaming system, wherein the power transmitter is configured to: controllably transmit an outgoing optical beam, wherein the outgoing optical beam is controlled such as to include either or both of: a safety beam component comprising light at a first wavelength, and a power beam component comprising light at a second wavelength; and control a direction at which the outgoing optical beam is emitted from the power transmitter, wherein the power transmitter comprises a plurality of optical components, including: a safety beam generator for generating the safety beam component; a power beam generator for generating the power beam component; an optical combiner, being optically coupled to the safety beam generator such as to receive the safety beam, and being optically coupled to the power beam shaping generator such as to receive the power beam, wherein the optical combiner is configured to combine the safety beam and the power beam such as to produce, as an output, a combined beam, wherein the safety beam and the power beam are aligned with one another in the combined beam.

[0029] Optionally, the power transmitter comprises a safety beam shaping mechanism optically coupled to the safety beam generator such as to receive the safety beam component generated by the safety beam generator, wherein the safety beam shaping mechanism is configured to optically modify the safety beam before the safety beam is received by the optical combiner.

[0030] Optionally, the power transmitter comprises a power beam shaping mechanism optically coupled to the power beam generator such as to receive the power beam component generated by the power beam generator, wherein the power beam shaping mechanism is configured to optically modify the power beam before the power beam is received by the optical combiner.

[0031] Optionally, the optical combiner comprises a dichroic mirror configured to either: substantially reflect the power beam component and to substantially transmit the safety beam component; or substantially reflect the safety beam component and to substantially transmit the power beam component.

[0032] Optionally, the plurality of optical components comprises: a combined beam shaping mechanism configured to receive the combined beam emitted by the optical combiner, wherein the combined beam shaping mechanism is configured to optically modify the combined beam, thereby modifying the safety beam component and the power beam component. The combined beam shaping mechanism may comprise a focusing element, such as a parabolic mirror.

[0033] Optionally, the plurality of optical components comprises: a fine-steering mechanism configured to receive the combined beam emitted by the optical combiner, wherein the fine-steering mechanism is configured to control, at least in part, a direction at which the combined beam is emitted from the power transmitter.

[0034] Optionally, the optical components are each fixedly located on a mounting board, such that a relative position and / or orientation of each optical component is fixed with respect to the mounting board and thereby to each other optical component. The mounting board may be controllably rotated such as to control, at least in part, an emission direction of the combined beam from the power transmitter. The power transmitter may comprise one or more alignment mechanism, at least one optical component may be associated with an alignment mechanism enabling the relative position and / or orientation of the at least one optical component with respect to the other optical components to be modified, the one or more alignment mechanism may be lockable such as to controllable lock against changes in the position and / or orientation of the associated optical component(s).

[0035] The power transmitter may be the power transmitter of the power beaming system.

[0036] According to another aspect of the present disclosure, there is provided a method for controlling operation of an outgoing optical beam generated by a power transmitter of a power beam system, comprising: controlling generation of a safety beam component of the outgoing optical beam and a power beam component of the outgoing optical beam, wherein the safety beam component comprises light at a first wavelength and the power beam component comprises light at a second wavelength, such as to controllably direct the outgoing optical beam towards a target airborne power receiver; monitoring one or more operational outputs of one or more operational subsystems, wherein the, or each, operational subsystem is configured to generate at least one operational output; determining a current operational status in dependence on the current one or more operational outputs; and controlling operation of the power beam such that the power beam is disabled when the current operational status is determined to include at least one blocking status.

[0037] According to another aspect of the present disclosure, there is provided a method for controlling operation of an outgoing optical beam generated by a power transmitter of a power beam system, comprising: controlling generation of a safety beam component of the outgoing optical beam and a power beam component of the outgoing optical beam, wherein the safety beam component comprises light at a first wavelength and the power beam component comprises light at a second wavelength, such as to controllably direct the outgoing optical beam towards a target airborne power receiver; monitoring one or more operational outputs of one or more operational subsystems, wherein the, or each, operational subsystem is configured to generate at least one operational output; determining a current operational status in dependence on the current one or more operational outputs; determining that the current operational status comprises at least one blocking status; and in response, controlling operation of the power beam such that the power beam is disabled.

[0038] Optionally, either method may be implemented by a transmitter controller of the power transmitter.

[0039] Optionally, at least one operational subsystem is configured to generate an associated operational output dependent upon data received from the power receiver via a wireless data channel.

[0040] Optionally, at least one operational subsystem is a flight telemetry operational subsystem configured to receive flight telemetry data from the power receiver via the wireless data channel, and to generate an associated flight telemetry operational output comprising the flight telemetry data. Either method may comprise determining a blocking status in response to determining, from the flight telemetry operational output, that the flight telemetry data indicates that the current flight of the power receiver fails to satisfy a predefined flight requirement.

[0041] Optionally, at least one operational subsystem is an auxiliary telemetry operational subsystem configured to receive auxiliary telemetry data from the power receiver via the wireless data channel, and to generate an associated auxiliary telemetry operational output comprising the auxiliary telemetry data. The auxiliary telemetry data may comprise temperature measurements, electrical supply measurements, etc. Either method may comprise determining a blocking status in response to determining, from the auxiliary telemetry operational output, that the auxiliary telemetry data indicates that at least one current measurement of the power receiver is indicative of a predefined fault condition.

[0042] Optionally, at least one operational subsystem is an active operational subsystem configured to generate an associated operational output based on active measurements made at the power transmitter, wherein the active measurements are of an interaction between the outgoing optical beam and the powerreceiver. At least one active operational subsystem may comprise an active operational output based on measurement made at the power transmitter of an interaction between the safety beam and the power receiver. Either method may comprise determining a blocking status in response to: determining a non- alignment condition between the safety beam and the power receiver; and / or determining that the current measurement of the interaction between the safety beam and the power receiver is indicative of a threshold likelihood of a foreign object interacting with the safety beam.

[0043] Optionally, at least one operational subsystem is a passive operational subsystem configured to generate an associated passive operational output based on passive measurements made at the power transmitter of the power receiver. The power transmitter may comprise an imaging arrangement. Either method may comprise at least one passive operational subsystem configured to generate an associated passive operational output utilising images of the power receiver captured by the imaging arrangement. Either method may comprise determining a blocking status in response to determining, from the images captured by the imaging arrangement, a fault flight condition of the power receiver.

[0044] Optionally, either method comprises: determining one or more combined statuses, wherein each combined status is associated with two or more operational outputs and is determined, at least in part, according to a comparison between its associated operational outputs, wherein the current control status is determined by reference to the current one or more operational outputs and the current one or more combined statuses. Either method may comprise, for a combined status: determining at least one of the operational outputs of the combined status indicates a first flight condition of the power receiver; determining at least one other of the operational outputs of the combined status indicates a second flight condition; determining that the second flight condition is inconsistent with the first flight condition; and in response, determining that the combined status comprises a blocking status.

[0045] Optionally, either method comprises implementing a startup procedure before activating the power beam, wherein the startup procedure comprises an initialisation routine and a sequence of two or more subsequent startup routines, comprising: during the initialisation routine, determining that the current operational status comprises an initial blocking status before proceeding to a first subsequent startup routine; for each subsequent startup routine: identifying at least one associated operational output of the one or more operational outputs, monitoring said at least one associated operational output during the subsequent startup, determining either a pass condition or fail condition for the subsequent startup routine based, at least in part, on the monitoring of said at least one associated operational output; and determining removal of the initial blocking status only upon determining a pass condition for every one of the two or more subsequent startup routines. Each subsequent startup routine after a first subsequent startup routinemay be initiated only upon determining a pass condition of a directly preceding subsequent startup routine in the sequence. For at least one subsequent startup routine, the safety subsystem may be configured to determine either the pass condition or fail condition for the subsequent startup routine based, at least in part, on at least one combined status. The initialisation routine may comprise determining, via wireless data communication between the power transmitter and the power receiver, a compatibility of the power receiver for receiving the optical beam.

[0046] Optionally, at least two operational statuses are transmitter operational statuses, and each transmitter operational status is generated without dependence on data receiver from the power receiver. Either method may comprise: monitoring at least one combined status being a transmitter-only combined status being a combined status based upon a comparison between two or more transmitter operational statuses; determining a blocking status in response to determining a discrepancy between at least a first transmitter operational status and a second transmitter operational status.

[0047] Optionally, the power receiver is affixed to an airborne vehicle.

[0048] According to another aspect of the present disclosure, there is provided a method of operating a power beaming system including the steps of: transmitting, by a power transmitter, an optical beam, the optical beam including light at a first wavelength and light at a second wavelength, distinct from the first wavelength; receiving, by a power receiver including a wavelength discriminator, the optical beam; returning, by the power receiver, the transmitted light at the first wavelength for receipt by the power transmitter; accepting, by the power receiver, the transmitted light at the second wavelength for optical-to- electrical power conversion; and influencing, by one or more processors, operation of the power transmitter based on the return light received at the power transmitter.

[0049] According to another aspect of the present disclosure, there is provided a power beaming initialisation method, the method including the steps of: at a power transmitter, transmitting a first optical beam including light at a first wavelength; at a power receiver, via a wavelength discriminator, returning the transmitted light at the first wavelength for receipt at the power transmitter; at the power transmitter, based on and subsequent to receipt of return light at the first wavelength, commencing transmitting a second optical beam including light at a second wavelength, distinct from the first wavelength; and at the power receiver, via the wavelength discriminator, accepting the transmitted light at the second wavelength for optical-to-electrical power conversion.

[0050] Optionally, the step of transmitting the second optical beam including light at the second wavelength includes continuing transmission of the first optical beam including light at the first wavelength.

[0051] According to another aspect of the present disclosure, there is provided a power beaming initialisation and interlock method, the method including the steps of the method of operating a power beaming system above, and further including the step of, at the power transmitter, ceasing light transmission at the second wavelength responsive to non-receipt or reduction of the return light at the first wavelength receiving at the power transmitter.

[0052] According to another aspect of the present disclosure, there is provided a power beaming interlock method, the method including the steps of: at a power transmitter, transmitting an optical beam including light at a first wavelength and light at a second wavelength, distinct from the first wavelength; at a power receiver, via a wavelength discriminator, returning the transmitted light at the first wavelength for receipt by the power transmitter, and accepting the transmitted light at the second wavelength for optical- to-electrical power conversion; and at the power transmitter, responsive to a predetermined condition, such as non-receipt or reduction, of the return light at the first wavelength receiving at the power transmitter, ceasing light transmission at the second wavelength.

[0053] As used herein, unless context requires otherwise, the words “comprise”, “comprises”, “comprising” and their variations are intended to be interpreted in the inclusive sense, rather than the exhaustive sense.

[0054] 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 wavelength and a second wavelength” has the same meaning as “a wavelength and another wavelength”.

[0055] As used herein, “light” and “optical beam” each refer to electromagnetic radiation having optical frequencies, including far-infrared radiation, infrared radiation, visible radiation and ultraviolet radiation.

[0056] As used herein a designation of a view or orientation, for instance a top view, a side view, horizontal or vertical is arbitrary for the purposes of illustration and does not suggest any required orientation.

[0057] When an element is referred to as being "connected" or "coupled" to or with another element, or when an element is referred to as “receiving” or “providing” a signal or light from or to another element, using those or words of the same or similar meaning, unless the context requires otherwise, the element can be directly connected or coupled to the other element, or intervening elements may be present. In otherwords, the element is not necessary directly connected or coupled to the other element without any intervening elements.

[0058] Further aspects of the present disclosure 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. It should be understood that the following description and accompanying drawings are not intended to limit the disclosure to the particular form disclosed. As used herein, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.BRIEF DESCRIPTION OF THE FIGURES

[0059] In order that the invention may be more clearly understood, embodiments will now be described, by way of example, with reference to the accompanying drawing, in which:FIG. 1A is a block diagram illustrating a power beaming system, according to one embodiment of the present disclosure.FIG. IB is a pictorial diagram illustrating a power beaming system, according to another embodiment of the present disclosure.FIG. 1C is a pictorial diagram illustrating a power beaming system, according to yet another embodiment of the present disclosure.FIGS. 2A and 2B display a front view and a perspective rear view, respectively, of an example of a dichroic retroreflector.FIGS. 3A and 3B illustrate staggered monitoring time windows and non-staggered monitoring time windows for monitoring photocurrent output.FIG. 4A is a collection of diagrams illustrating a spatial buffer provided by a safety beam around a power beam, according to still yet another embodiment of the present disclosure.FIG. 4B is a collection of diagrams illustrating an obstacle intruding the spatial buffer of FIG. 4A.FIG. 4C is a collection of diagrams illustrating a spatial buffer provided by a safety beam around a power beam, according to an alternative embodiment of the present disclosure.FIG. 4D is a collection of diagrams illustrating an obstacle intruding the spatial buffer of FIG. 4C.FIG. 5 is a flowchart illustrating a power beaming safety method, according to some embodiments of the present disclosure.FIG. 6 is a flowchart illustrating a power beaming initialization method, according to some embodiments of the present disclosure.FIG. 7 is a flowchart illustrating a power beaming interlock method, according to some embodiments of the present disclosure.FIG. 8 is a block diagram representation of a safety subsystem and various operational subsystems according to an embodiment of a transmitter controller.FIG. 9 shows a multi-stage startup method according to an embodiment.FIG. 10 shows a power transmitter comprising distinct light generators for generating the safety beam and the power beam.FIG. 11 shows a transmitter controller including a redundancy sub-system.DESCRIPTION OF EMBODIMENTS

[0060] FIG. 1A is a block diagram representation of a power beaming system 10, according to an embodiment of the present disclosure. Broadly, the power beaming system 10 comprises a power transmitter 11 and at least one power receiver 12 (one power receiver 12 is shown in FIG. 1A). FIG. IB is a pictorial diagram that depicts a power beaming system 100, according to an embodiment of the present disclosure, showing in this case a ground-based stationary power transmitter 110 and an airborne power receiver 120 (the power receiver 120 is shown as located on an aerial vehicle 150, in this case, a drone). Like elements of FIGs. 1A and IB are labelled with like references.

[0061] As shown in FIG. IB, the power transmitter 11, 110 is configured to transmit, via an outgoing beam generator 118 (see FIG. 1A), an outgoing optical beam 135A including a first component beam comprising light at a first wavelength and a second component beam comprising light at a second wavelength. In some embodiments, the first wavelength may be within an eye-safe wavelength band, for example centred around 1550 nm, and therefore the first component beam is also referred to herein as a “safety beam”. The second wavelength may be within an atmospherically least absorptive wavelength band, for example within the spectral region of 700 to 1150 nm, such as around 1070 nm or 1080 nm. In embodiments, most optical power is contained within second component beam. The second component beam is also, therefore, referred to herein as a “power beam”. In contrast, optical power of the safety beam is limited, by design. In this way, the outgoing optical beam 135A can be understood as comprising anoutgoing safety beam and an outgoing power beam. In some embodiments, the power transmitter 11, 110 is ground-based or stationary.

[0062] In an embodiment, the power transmitter 11, 110 comprises a transmitter controller 114 comprising one or more processors configured to control operation of the power transmitter 11, 110. The one or more processors of the transmitter controller 114 of the power transmitter 11, 110 may take the form of: one or more field-programmable gate arrays (FPGA), one or more application-specific integrated circuits (ASIC), one or more microprocessors, one or more microcontrollers, or a combination thereof. The one or more processors may include or be operatively coupled to a memory, such as volatile or non-volatile memory, for storing data or instructions. Where the memory store processor-readable instructions, the processor-readable instructions may be adapted to control the one or more operations of the power transmitter 11, 110. The power transmitter 11, 110 can comprise a data communication interface (not shown) for data communication with remotely based computers (e.g., via a network which can include the Internet), for example, such as allowing for user control of the power transmitter 11, 110 via a remotely based computer.

[0063] As described herein, the outgoing optical beam 135A is controlled by the transmitter controller 114 such as to emit either only the first component beam comprising light at the first wavelength (safety beam) or both of the first component beam comprising light at the first wavelength (safety beam) and the second component beam comprising light at the second wavelength (power beam) simultaneously, as required. That is, at any one time, the outgoing optical beam 135A is either off (not emitted), emitted comprising only the safety beam, or emitted comprising both the safety beam and the power beam.

[0064] In the embodiments of FIGs. 1A and IB, the power beaming system 10, 100 also includes the power receiver 12, 120 for receiving the outgoing optical beam 135A. The power receiver 12, 120 further includes a wavelength discriminator 13, 130 configured to return (e.g., via reflection) the transmitted light at the first wavelength (i.e., the safety beam) as an incoming optical beam 135B for receipt by the power transmitter 11, 110. The wavelength discriminator 13, 130 is also configured to accept the transmitted light at the second wavelength (i.e., the power beam) for optical-to-electrical power conversion. That is, the wavelength discriminator 13, 130 is configured to substantially not reflect the power beam. In some embodiments, the power receiver 12, 120 is airborne or mobile, for example installed on an aerial vehicle 150 (e.g., a drone or other electric aircraft). In use, the power receiver 12, 120 may be moving at a speed of at least 1 m / s, or in some cases at least 5 m / s, or in other cases at least 10 m / s.

[0065] In an embodiment, the power receiver 12, 120 comprises a receiver controller 122 comprising one or more processors configured to control operation of the power receiver 12, 120. The receiver controller 122 can comprising one or more of: one or more field-programmable gate arrays (FPGA), one or more application-specific integrated circuits (ASIC), one or more microprocessors, one or more microcontrollers, or a combination thereof. The receiver controller 122 can be operatively interfaced with an aircraft controller (not shown) of the aerial vehicle 150 on to which it is installed. For example, the receiver controller 122 can be in data communication with the aircraft controller via a shared data bus or a shared memory. Here, the aircraft controller is understood as implementing flight control functionality of the aerial vehicle 150. In an embodiment, the receiver controller 122 is implemented, at least in part, within the same hardware as the aircraft controller; that is, the receiver controller 122 is effectively a functional module of the aircraft controller. In an embodiment, the receiver controller 122 is implemented, at least in part, in separate hardware to the aircraft controller; in this case, the receiver controller 122 can be in data communication with the aircraft controller (e.g., via a suitable serial or parallel data bus). The functionality of the receiver controller 122 as described herein can be distributed across a plurality of hardware processing units, for example, the receiver controller 122 can be implemented by a combination of the aircraft controller and separate processing hardware to the aircraft controller.

[0066] In an embodiment, the power receiver 12, 120 is configured to continuously generate real-time flight telemetry data. The flight telemetry data comprises position data corresponding to measurements of the position of the power receiver 12, 120. In an embodiment, the power receiver 12, 120 comprises a positioning module 126 operably interfaced with the receiver controller 122. The positioning module 126 is configured to continuously obtain the position measurements. The position measurements can include orientation measurements. Measurements of the velocity and acceleration of the power receiver 12, 120 can also be measured or otherwise calculated by the positioning module 126.

[0067] Herein, “continuously” as applied to data generation or acquisition may be understood to mean that data is generated or acquired (or otherwise obtained) periodically with a sufficiently large sampling frequency to capture changes the quantity or quantities represented by the data (e.g., flight telemetry) with sufficient resolution for use by the system 10, 100. For example, in terms of flight-telemetry data, a sampling frequency of around 1000 Hz may be utilised. In one or more other embodiments, “continuously” can be understood to include data generated asynchronously or intermittently (i.e., with a variable period between adjacent data points), as long as a maximum period between adjacent data points is sufficiently small to capture relevant changes in the quantity or quantities represented by the data.

[0068] Herein, data described as being “real-time” should be understood as indicative of data utilised by the system 10, 100 which is representative of a sufficiently current state of the system 10, 100. Although there is inevitably a delay of time between when a measurement is made and when data representing that measurement is useable by the power transmitter 11, 110, power receiver 12, 120, or any other component of the system 10, 100, reference to “real-time” should be understood as indicative of a sufficiently small delay that said data is expected to remain effectively representative of a current state of the system 10, 100.

[0069] The positioning module 126 can comprise a GPS unit configured to continuously measure a position (using the Global Positioning System (GPS)) of the power receiver 12, 120. Alternatively, another global navigation satellite system (GNSS) can be utilised in place of, or in combination with, GPS, such as one or more of the BeiDou Navigation Satellite System (BDS) and the Galileo system. The positioning module 126 can comprise an inertial measurement unit (IMU). For example, the measurements made by the GPS unit and the IMU are combined, using known techniques, to produce the positioning measurements. The GPS unit and IMU can be integrated. The GPS unit can implement real-time kinematic (RTK) GPS, which may advantageously provide for improved positioning measurements (e.g., improved accuracy of the positioning measurements). One example of hardware for the GPS unit is a u-blox F9P.

[0070] Alternatively, the power receiver 12, 120 can be operably interfaced with GPS hardware of the aerial vehicle 150 itself (not shown), such that the power receiver 12, 120 continuously receives measurements of the position of the aerial vehicle 150. In this case, the positioning module 126 may be understood as the logical interface between the receiver controller 122 and a computing unit(s) of the aerial vehicle 150. In this way, the position measurements of the power receiver 12, 120 can be determined or at least estimated with sufficient accuracy for use within the system 10, 100 from the measurements of the position of the aerial vehicle 150. Unless stated otherwise, herein it is assumed that the position measurements are made by, at least, a GPS unit 127a of the power receiver 12, 120.

[0071] In an embodiment, the power transmitter 11, 110 comprises a transmitter-side wireless data communication module (“transmitter communication module”) 116 and the power receiver 12, 120 comprises a receiver-side wireless data communication module (“receiver communication module”) 124. The transmitter data module 116 is configured for wireless data transmission via a wireless communication channel with the receiver data module 124 (and vice versa). The wireless data transmission can be via a radiofrequency channel, for example utilising a 915 MHz carrier band. It is expected that other wireless data transmission technologies can be utilised, such as using an optical laser based data communication channel. Herein, reference to the power transmitter 11, 110 receiving or sending data from the power receiver 12, 120 should be understood as being data transmitted from the power receiver 12, 120 to thepower transmiter 11, 110 via this wireless communication channel, and vice versa, unless stated otherwise. Depending on the embodiment, the transmiter communication module 116 can be distinct from the data communication interface or these can form an integrated unit. In FIG. 1A, the wireless communication channel is represented by a broken line connecting the transmiter communication module 116 and the receiver communication module 124.

[0072] In an embodiment, the receiver controller 122 is configured to continuously communicate the telemetry data including the position measurements to the transmiter controller 112 via the wireless communication channel, such that the transmiter controller 112 has access to position measurements reflective of a current position of the power receiver 12, 120. The wireless communication channel can be configured to provide relatively low latency data communication between the receiver controller 122 and transmiter controller 114, such as a latency around or lower than 1 ms. Low latency may have the advantage of ensuring that the positioning data is associated with positioning measurements made sufficiently close in time to receipt of the positioning data at the transmiter controller 114, such that the positioning data represents close enough to the current position of the receiver controller 122 to enable use of the positioning data by the transmiter controller 114.

[0073] FIG. 1C is a pictorial diagram that depicts yet another power beaming system 102, according to yet another embodiment of the present disclosure. The power beaming system 102 of FIG. 1C is similar to the power beaming system 100 of FIG. IB. Identical and like elements of FIGs. IB and 1C are labelled with identical and like references, respectively. The power beaming system 102 is different from the power beaming system 100 in that the former includes a second power transmiter 112, also operatively coupled to the transmiter controller 114. The second power transmiter 112, like the (first) power transmiter 110, is configured to transmit an outgoing optical beam 135C including light at the first wavelength and light at the second wavelength (therefore, the second power transmiter 112 is configured for transmiting a power beam and a safety beam, separately to the power beam and safety beam of the first power transmiter 110). Upon receiving the outgoing optical beam 135C by the power receiver 120, the wavelength discriminator 13, 130 is configured to return the transmited light at the first wavelength in an incoming optical beam 135D to the second power transmiter 112, and accept the transmited light at the second wavelength for optical-to-electrical power conversion.

[0074] While FIG. 1C depicts two outgoing beams 135 A and 135C (associated with two separate power transmiters 110, 112 respectively), in practice, at least in some embodiments, only one of the two outgoing beams 135A, 135c is actively directed towards a particular power receiver 120 at a time. In other words, where the power beaming system 102 has multiple power transmiters 110, 112, hence multiple outgoingbeams 135 A, 135C, the power receiver 12, 120 may be configured to receive only one of the multiple outgoing beams 135A, 125C at a time. For example, in FIG. 1C, the dichroic retroreflector of the power receiver 120 is gimbal mounted. The gimbal-mounted dichroic retroreflector may be controllably adjusted, for example in its azimuth angle and / or elevation angle for alignment with the desired power transmitter 110, 112, such as power transmitter 112, instead of power transmitter 110. More generally, the power beaming system 102 of FIG. 1C can comprise two or more power transmitters 110, 112.

[0075] In an embodiment, the same transmitter controller 114 is configured to also influence operation of the second power transmitter 112. In an alternative embodiment, a different transmitter controller (not shown) is provided to influence operation of the second power transmitter 112. Regardless, the multiple power transmitters 110, 112, including at least the first power transmitter 110 and the second power transmitter 112, may form a network of power transmitters 110, 112 that are remote from one another. Each power transmitter 110, 112 in the network of power transmitters 110, 112 may cover a respective zone of ground area or air space. By locating the network of power transmitters 110, 112 in accordance with the respective zones of ground area or air space, for example slightly overlapping neighbouring zones, the network of power transmitters 110, 112 may extend the range of power delivery or charging by way of installing more power transmitters 110, 112. As the wavelength discriminator 13, 130 can have a limited angle of acceptance of an outgoing optical beam 135A, 135C, the minimum and / or maximum separation between neighbouring power transmitters 110, 112 in the network can be dependent on the angle(s) of acceptance of the power receiver(s) 120 able to utilise the network of power transmitters 110, 112.

[0076] Herein, the labels “outgoing” and “incoming” used in relation to the optical beams 135A, 135B, 135C, 135D are used from the perspective ofthe power transmitter 11, 110, 112. Unless the context requires otherwise, for consistency purposes, the same labels remain even if the description is from the perspective of the power receiver 12, 120. For example, an “outgoing” optical beam 135A, 135C is associated with an optical beam 135 A, 135C propagating from a respective power transmitter 11, 110, 112 towards a power receiver 12, 120. Similarly, an “incoming” optical beam 135B, 135D is associated with an optical beam 135B, 135D propagating from the power receiver 12, 120 towards a power transmitter 11, 110, 112 (i.e., being a reflected component of an incoming optical beam 135A, 135C, when reflected from the wavelength discriminator 13, 130 of a power receiver 12, 120). Therefore, an outgoing optical beam 135A, 135C is one that is received at apower receiver 12, 120 and an incoming optical beam 135B, 135D is one that is received at a power transmitter 11, 110, 112.

[0077] In an example use case, a power transmitter 11, 110, 112 is configured to direct its outgoing optical beam 135 A, 135C towards a first power receiver 12, 120 for a first period of time. The first periodof time can end, for example, when the first power receiver 12, 120 no longer requires reception of the outgoing optical beam 135 A, 135C (e.g., in a case when its batteries are sufficiently charged). More generally, the first period of time ends when the power transmitter 11, 110, 112 ceases directing the outgoing optical beam 135A, 135C towards the first power receiver 12, 120. Subsequently, the power transmitter 11, 110, 112 is configured to direct its outgoing optical beam 135 A, 135C towards a second power receiver 12, 120 for a second period of time. Again, the second period of time in a general sense ends when the power transmitter 11, 110, 112 ceases directing the outgoing optical beam 135A, 135C towards the second power receiver 12, 120. The first power receiver 12, 120 can be located at a substantially different spatial position to the second power receiver 12, 120, and therefore, the power transmitter 11, 110, 112 can be configured to controllably direct the outgoing optical beam 135 A, 135C in different spatial directions.

[0078] For clarity purposes, in FIGs. IB and 1C, an outgoing optical beam 135A, 135C and the corresponding resulting incoming optical beam 135B, 135D are depicted with offset light paths, in order to clearly distinguish the various optical beams 135A, 135B and 135C, 135D. The depicted offset is however not generally representative of the actual light paths. In practice, an outgoing optical beam 135A, 135C and its corresponding incoming optical beam 135B, 135D may overlap substantially in space.

[0079] In one or more embodiments, the power receiver 12, 120 includes one or more reflectors, such as retroreflectors. At least one retroreflector can comprise a dichroic retroreflector. To return light at the first wavelength (i.e., the safety beam), the dichroic retroreflector may be configured to retroreflect substantially the transmitted light at the first wavelength (e.g., substantially only the safety beam is reflected by the dichroic retroreflector) back to the power transmitter 11, 110, 112. Use of a retroreflector may allow for a wider acceptance angle for the incoming beam 135 A, 135C while still redirecting the outgoing beam 135B, 135D back towards the power transmitter 11, 110, 112.

[0080] FIG. 2A shows a front view of a dichroic retroreflector 200 according to one or more embodiments. The dichroic retroreflector 200 includes a dichroic comer cube reflector 202. The dichroic comer cube reflector 202 may be constmcted with three surfaces 202A, 202B, 202C.

[0081] Referring to FIG. 2B, the wavelength discriminator 13, 130 may be adjustably mounted with respect to the vehicle 150 such as to allow for controlled alignment of the wavelength discriminator 13, 130 with the outgoing beam 135A. The receiver controller 122 can be configured for controlling alignment of the wavelength discriminator 13, 130. For example, the dichroic retroreflector 200 can be gimbal-mounted. The dichroic retroreflector 202 may be operatively coupled with a gimbal 204. The gimbal 204 may in turnbe operatively coupled with a mounting assembly 206 for support. The gimbal 204 may be adjusted in two dimensions (e.g., via control of one or more motors, controlled by the receiver controller 122, and arranged to controllably adjust the gimbal 204), for example, in its azimuth angle and / or its elevation angle, to thereby cause adjustment of the relative rotational position of the wavelength discriminator 13, 130 with respect to the mounting assembly 206 and, therefore, the vehicle 150. Gimbal adjustment may be beneficial in improving the acceptance angle of the dichroic retroreflector 200.

[0082] In an embodiment, the receiver controller 122 is configured to determine an initial target azimuth angle and / or a target elevation angle for the wavelength discriminator 13, 130 based on the position data generated by the positioning module 126. The position data can be compared to a known position of the power transmitter 11, 110, 112 (for example, the position of the power transmitter 11, 110, 112 can be communicated to the receiver controller 122 from the transmitter controller 114). The position data generated at the power receiver 12, 120 that is indicative of the position of the power receiver 12, 120 can be represented in a same frame of reference as the position ofthe power transmitter 11, 110, 112 (e.g., using an absolute coordinate system), to enable a direct comparison between the position of the power transmitter 11, 110, 112 and the current position of the power receiver 12, 120.

[0083] In some embodiments, the gimbal 204 is dynamically adjusted (e.g., after an initial target azimuth angle and / or target elevation angle is determined) by the receiver controller 122 of the power receiver 120. The receiver controller 122 may be configured to adjust the azimuth angle and / or the elevation angle based on received optical power of the transmitted light. The wavelength discriminator 13, 130 may be configured to be gimballed towards the power transmitter 110, for example within a defined angle, such as less than 4 degrees, or preferably less than 2 degrees, or more preferably less than 1 degree, or even more preferably less than 0.5 degree. For example, the angle may be dynamically adjusted (e.g. to be dynamically corrected within the defined angle) by maximising the received optical power of the transmitted light. The received optical power may be measured by way of an optical splitter (e.g. 99 / 1 splitter) followed by a photodetector assembly (e.g. comprising one or more photodetectors). For example, at least one photodetector comprises a photodiode. An output of the photodetector assembly may be provided to the receiver controller 122. As a result, deviations in amount of return signal may be confined within 0.2%, or preferably within 0.1%, or more preferably within 0.05%.

[0084] To accept light at the second wavelength, the dichroic retroreflector 200 may be additionally configured to pass through substantially the transmitted light at the second wavelength (i.e., the power beam is substantially not absorbed or reflected by the dichroic retroreflector 200). The surfaces of the wavelength discriminator 130 may be optically coated (e.g. double-coated) to provide dichroic properties. For example,the surfaces may be optically coated to provide at least 90% reflectivity, preferably at least 95% reflectivity and more preferably at least 98.5% reflectivity, at the first wavelength. Alternatively or additionally, the surfaces may be optically coated to provide at most 1% reflectivity, preferably at most 0.5% reflectivity and more preferably at most 0.4% reflectivity, at the second wavelength.

[0085] In at least one embodiment in which the wavelength discriminator 130 includes a dichroic comer cube reflector 202, the effective reflectivity at the second wavelength after reflection off its three surfaces 202A, 202B, 202C is the cube of its surface reflectivity in respect of the second wavelength. For example, if the surface reflectivity at the second wavelength is at most 1%, then the effective reflectivity is (1%)3= 0.0001%. As another example, if the surface reflectivity at the second wavelength is at most 0.4%, then the effective reflectivity is (0.4%)3= 0.0000064%. Use of a comer cube reflector 202 therefore may advantageously enhance safety by reducing the reflected power of the power beam from the power receiver 12, 120. It should be understood that generally some portion of the power beam is reflected by the wavelength discriminator 130, however, the reflectivity is selected such as to be sufficiently low that the power of any reflected component of the power beam is below relevant safety thresholds.

[0086] In embodiments, the power beaming system 10, 100 further includes a photo-voltaic (PV) assembly configured to convert optical power contained in the power beam (i.e., the transmitted light at the second wavelength) to electrical power. The PV assembly may include one or more PV cells (not shown). The one or more PV cells may be selected to be absorptive, ideally most absorptive, to the second wavelength in which substantially all of the optical power of an outgoing optical beam 135 A, 135C is contained (i.e., a power beam). For example, if the wavelength of light accepted by the wavelength discriminator 13, 130 for optical-to-electrical power conversion purposes is 1070 nm or 1080 nm, then PV cell(s) with absorption spectmm that peaks at or near a 1070nm or 1080 nm band (respectively) is / are selected. For example, the PV cells may correspond to III-IV semiconductor alloy whose band-gap is tuned to have activation energy near 1070 nm or 1080 nm photons. The electric power obtained by converting the incident optical power may be used to power a power-consuming apparatus, such as an aerial vehicle 150, on which the power receiver 12, 120 may be supported or installed. Alternatively or additionally, the electric power may be used to recharge a power storage device, such as a battery on the aerial vehicle 150, on which the power receiver 12, 120 is supported or installed. The one or more PV cells can be located substantially directly behind the dichroic comer cube reflector surfaces 202A, 202B, 202C, such that the PV cells receive the incident power beam shortly after it has passed through the dichroic comer cube reflector surfaces 202A, 202B, 202C. Therefore, the optical coating referred to above should transmit substantially all of the second component beam (i.e., the power beam), such that it is available for absorptionby the PV cell(s). For aerial vehicles 150, such as drones or electric aircraft, power provision may be achieved by way of installing a power receiver 12, 120 on such an aerial vehicle and charging it or its battery in-flight from a ground-based power transmitter 11, 110, 112 via a group-to-air optical beam 130A. One or more embodiments of the present disclosure may advantageously provide added safeguards to a power beaming system that provides wireless energy to, and hence extending the inherent range of, such aerial vehicles.

[0087] In an embodiment, the power transmitter 11, 110, 112 includes one or more photodetectors (e.g. photodiodes) (not shown) for measuring a power of incoming light, for example, primarily expected to comprise a reflected component of the safety beam. In a general sense, the one or more photodetectors provide a photocurrent signal dependent upon an intensity of light incident onto the one or more photodetectors. The transmitter controller 114 is configured to monitor a strength of the photocurrent signal over time, for example, via an analogue-to-digital converter (ADC). The response of the one or more photodetectors is proportional to, or at least monotonically correlated to, the intensity of received light. For example, a steady intensity of the return light received by the power transmitter 11, 110, 112 corresponds to a steady photocurrent. An increase in the intensity of the return light produces a corresponding increase to the photocurrent signal. Similarly, a reduction in the intensity of the return light produces a corresponding reduction to the photocurrent current. Therefore, any change (over time) in the photocurrent signal is indicative of a corresponding change in the intensity of the return light. The one or more photodetectors can form part of a photodetector assembly, as described in the Applicant’s co-pending applications. Accordingly, based on the photocurrent signal, the transmitter controller 114 is configured to identify changes in the intensity of the return light. The transmitter controller 114 can be configured to influence operation of the power transmitter 11, 110, 112 based on changes in the intensity of the return light.

[0088] In an embodiment, the power transmitter 11, 110, 112 includes a circulator (not shown). The circulator includes at least three ports or apertures: an input port or aperture, a bidirectional port or aperture, and an output port or aperture. The input port or aperture may be optically coupled to one or more laser sources, such that the input port receives light generated by the one or more laser source (for example, said light comprising the safety beam and the power beam). The bidirectional port or aperture is optically coupled to air or freespace, for transmitting outgoing light (e.g., transmitting the outgoing optical beam 135 A, 135C comprising both the safety beam and the power beam) and receiving the return incoming light (e.g., expected to primarily consist of a reflected portion of the safety beam). The output port or aperture is optically coupled to, and provides the received light, to the one or more photodetectors. Advantageously,the circulator may ensure that a reception axis and a transmission axis are aligned, as the output transmission port is the same as the input reception port.

[0089] In embodiments, the transmitter controller 114 is configured to sample the photocurrent signal at a predefined sampling interval. For example, the sampling interval is no greater than a 1 ms, or preferably no greater than 0.1 ms, or more preferably no greater than 0.02 ms. These sampling intervals correspond to, respectively, sampling frequencies of no less than 1 kHz, or preferably no less than 10 kHz, or more preferably no less than 50 kHz. The intensity of return light can be affected due to atmospheric fluctuations, such as presence of atmospheric particles, for example dust, and / or fog or cloud (or other phenomenon due to water particles present in the atmosphere). Such fluctuations typically cause the return light intensity to vary in the order of milliseconds. As such, a sampling interval of no greater than 1-10 ms is considered suitable in filtering out most if not all atmospheric fluctuations. Further, the transmitter controller 114 is configured to identify the occurrence of at least one predetermined condition. For example, the transmitter controller 114 is configured to monitor the photocurrent signal in order to identify predefined changes (e.g. a predefined percentage change) in the sampled photocurrent signal over a defined duration, such as a monitoring time window. For example, the monitoring time window is no more than 2 ms, preferably no more than 1 ms, or more preferably no more than 0.5 ms. Each monitoring time window has an associated start time and an associated end time.

[0090] In some embodiments, the monitoring time window re-starts after each sampling interval. For example, referring to FIG. 3A, at a sampling interval 302 of 0.1 ms, the transmitter controller 114 may monitor over a monitoring time window 300A of 1 ms (i.e. from the 1st sampling point to the 10th sampling point) for changes in the photocurrent output 304. As the transmitter controller 114 completes sampling the next sample (i.e. the 11th sample 306A), the transmitter controller 114 may monitor over a monitoring time window 308 A of the immediately preceding 1 ms (i.e. from the 2nd sampling point to the 11th sampling point) for changes in the photocurrent. Thereafter, transmitter controller 114 completes sampling the next sample (i.e. the 12th sample), the transmitter controller 114 may monitor over a monitoring time window of the immediately preceding 1 ms (i.e. from the 3rd sampling point to the 12th sampling point) for changes in the photocurrent, and so on. Accordingly, in these embodiments, the successive monitoring time windows 300A, 308A are staggered. In alternative embodiments, the monitoring time window re-starts after the previous monitoring time window ends.

[0091] Referring to FIG. 3B and continuing with the example of a sampling interval 302 of 0. 1 ms and a monitoring time window 300B of 1 ms, here, the transmitter controller 114 is configured to sample the next 10 samples (i.e. the 11th to 20th samples) before re-starting the next monitoring time window 308Bof 1 ms. Accordingly, in these alternative embodiments, the successive monitoring time windows are nonstaggered. Use of staggered monitoring time windows allows for more regular monitoring, such as rolling mean received power. Conversely, use of non-staggered monitoring time windows may advantageously lower processor requirements. Further, the shorter the monitoring time window, the quicker the transmitter controller 114 may respond to influence operation of the system 10, 100, such as ceasing transmission of the power beam by the power transmitter 11, 110, 112. In embodiments, consistent with the duration of the monitoring time window, the response time of the transmission cessation is no more than 2 ms, preferably no more than 1 ms, more preferably no more than 0.5 ms, or even more preferably no more than 0.25 ms.

[0092] Because the wavelength discriminator 13, 130 of the power receiver 12, 120 is configured to reflect the safety beam (light at the first wavelength) and accept the power beam (light at the second wavelength), the return light received at the power transmitter 11, 110, 112, is mostly light at the first wavelength. For this reason, the one or more photodetectors of the power transmitter 11, 110, 112 are selected to be sensitive to the first wavelength. For example, if the wavelength of light returned by the wavelength discriminator 13, 130 for receipt by the power transmitter 11, 110, 112 is at is 1550 nm, then photodetector(s) sensitive to a 1550 nm wavelength band is / are selected.

[0093] In an embodiment, the transmitter controller 114 is configured to adjust a direction of the outgoing beam 135A, 135C, comprising either or both of the safety beam and the power beam, towards the power receiver 12, 120. The transmitter controller 114 may cause adjustment to the direction of the outgoing beam 135A, 135C based on changes in the return light. For example, the power transmitter 11, 110, 112 may include a piezoelectric mirror to re-direct the outgoing beam 135A, 135C. The transmitter controller 114 may cause actuation of the piezoelectric mirror based on changes in the return light. The transmitter controller 114 may determine an optimum direction of the outgoing beam 135A, 135C by maximising the amount of return light, using, for example, a gradient ascent algorithm. Determining the optimum direction allows the power transmitter 11, 110, 112 to direct the outgoing beam 135A, 135C towards the power receiver 12, 120. Where the power receiver 12, 120 is moving, the determination may be repeated regularly to track the moving power receiver 12, 120.

[0094] In embodiments, the influenced operation of the system 10, 100, 102 includes at least partial cessation of transmission of at least the power beam by the power transmitter 11, 110, 112. Cessation of transmission of the power beam, even partially, may reduce the risk potential harm caused by an intense laser. In other embodiments, the influenced operation of the system 10, 100, 102 may include full cessation of transmission of at least the power beam by the power transmitter 11, 110, 112. The at least partial cessation of transmission of the power beam may be based on a predetermined condition, such as non-receipt or reduction, of the return light received at the power transmitter 11, 110, 112. For example, the transmitter controller 114 may monitor the return light (e.g. its intensity or power) by monitoring the photodetector current output. Upon determining that the received return light deviates from the predetermined condition, the transmitter controller 114 may influence operation of the system 10, 100, 102. Transmission of the power beam may be ceased upon determining a deviation from the predetermined condition. Transmission of the safety beam may continue. Alternatively transmission of both the power beam and the safety beam may be ceased.

[0095] In an embodiment, in order to cease transmission, the transmitter controller 114 is configured to control actuation of a solid state relay that switches the power transmitter 11, 110, 112. The actuation may be based on amplitude-shift keying, however other modulation methods may also be used. Further, the actuation may be based on triple modular redundancy to improve fault-tolerance of the transmission cessation. The solid state relay allows rapid cessation in transmission of the power beam by the power transmitter 11, 110, 112. In embodiments, the cessation of transmission occurs within no more than 2 ms, preferably no more than 1 ms, more preferably no more than 0.5 ms, and even more preferably no more than 0.25 ms. As the safety beam is of relatively low power, and preferably below a regulatory power threshold, transmission of the safety beam may be advantageously continued even when the power beam transmission is halted. This is on the basis that the safety beam does not pose a significant risk (being under the regulatory power threshold), even if it is projected past the power receiver 12, 120 due to a potential misalignment between the power receiver 12, 120 and the outgoing beam 135A, 135C.

[0096] In embodiments, the predetermined condition is one or more defined power changes (i.e., a measured change in the power or intensity of the reflected portion of the safety beam as measured at the power transmitter 110, 112). Power changes may be as a result of any one or more of: an obstacle intruding the optical beam path, the outgoing beam 135A, 135C deviating from or not fully received by the power receiver 120, the outgoing beam 135 A, 135C not fully returned by the power receiver 120, and the incoming beam 135B, 125D deviating from or not fully received by the power transmitter 11, 110, 112. A defined power change may be presented as a defined percentage change, such as at least 0.5%, at least 1%, at least 1.5%, or at least 2%. The defined power change may be measured relative to one or more defined power levels. In some embodiments, the defined power level includes the average received power of the return light measured during any monitoring time window (e.g. rolling mean received power for staggered monitoring time windows). For example, the transmitter controller 114 may determine whether or not there is a defined percentage change from the average received power. Alternatively or additionally, the defined power level includes the range of power of the return light measured during the monitoring time window.For example, the transmitter controller 114 may determine whether or not there is a defined percentage change in the range of return power. Still alternatively or additionally, the defined power level is based on telemetric information. For example, the system 10, 100, 102 can be configured to obtain and reconcile telemetric information, such as power reception telemetry data and / or kinematic GPS data (such as realtime kinematic of RTK GPS data), with the photodetector output. The system 10, 100, 102 may determine whether or not there is a defined percentage discrepancy between the telemetric information and photodetector output.

[0097] Referring to FIGs. 4A-4D, in some embodiments, an outgoing optical beam 135 A, 135C includes a first constituent beam (i.e., safety beam) 402 including the light at the first wavelength and a second constituent beam (i.e., power beam) 404, distinct from the first constituent beam 402, including the light at the second wavelength. It shall become apparent that the safety beam 402 is intended for safety purposes, whereas the power beam 404 is intended for power delivery purposes. The safety beam 402 may contain optical power in the order of 1 W, whereas the power beam 404 may contain optical power in the order of 2 kW. The first wavelength may be an eye-safe wavelength, for example within the 1550 nm wavelength band. The second wavelength may be an atmospherically less or least absorptive wavelength, for example within the 1070 nm or 1080 nm wavelength bands.

[0098] FIGs. 4A-4D illustrate examples of the respective beam widths of the safety beam 402 and the power beam 404, in both the outgoing beam 135A, 135C and incoming the beam 135B, 135D. Subsets (a) and (b) plots their intensity profile over radial distance x and / or y at two different propagating distances, one at around the beam waist, where Gaussian-profile coherent light (M2 factor of 1) converges to the narrowest beam width, and another away from the beam waist, close to or at the power transmitter. Also plotted in subsets (a) and (b) are the contour plots of their full-widths at half maximum (FWHM). Subset (c) plots their FWHM over propagating distance z.

[0099] In FIGs. 4A-4D, beam waist locations for the safety beam 402 and the power beam 404 are depicted to be the same. In practice, the beam waist location may be different. The beam waist location may be dependent on, and / or adjusted by, beam divergence 0 =which scales directly proportionally with wavelength A and inversely proportionally with beam waist w0. In this example, the wavelengths of the safety beam and the power beam are selected to be approximately 1550 nm and approximately 1070 nm or 1080 nm, in either case, that is a ratio of approximately 1.5 to 1. Accordingly, as will be further described below, a safety beam size of around 1.5 times, for example between 1.2 times and 2 times, of a power beam size will result in similar divergence and beam waist locations for the safety beam 402 and the power beam 404. The safety beam 402 may be approximately 50 mm in diameter(FWHM), such as between 25 mm and 100 mm. For example, at their beam waists, where the power beam 404 is approximately 50 mm in diameter (FWHM), the safety beam 402 is approximately 60 to 100 mm in diameter (FWHM). As another example, at their beam waists, where the power beam 404 is approximately 100 mm in diameter (FWHM), the safety beam 402 is approximately 120 to 200 mm in diameter (FWHM). As yet another example, at their beam waists, where the power beam 404 is approximately 25 mm in diameter (FWHM), the safety beam 402 is approximately 30 to 50 mm in diameter (FWHM). Because of beam divergence, the safety beam 402 and the power beam 404 will expand in size away from their beam waists. The beam size of the safety beam 402 and the power beam 404 away from their beam waists may be between 1.1 and 4 times the beam waist, or between 1.5 to 3.5 times the beam waist, or between 2 and 3 times their respective beam waist. The beam sizes exemplified in absolute terms are for illustrative purposes only, and are not intended to limit the scope of the present disclosure.

[0100] In some embodiments, as illustrated in FIGs. 4A and 4B, the power transmitter 110, 112 is configured to converge the outgoing beam 135A, 135C, at least initially. The outgoing beam 135A, 135C is converged to a beam waist and then diverges in an opposite manner. In the illustrated scenario of FIG. 4A, the power receiver 120 is located at a target maximum range of the power beaming system 10, 100, 102. The target maximum range may be in the vicinity of one to a few hundred meters, such as no less than 100 m, no less than 200 m, or no less than 400 m. The distance between the power transmitter 11, 110, 112 and the maximum range of the power beaming system 10, 100, 102 is referred to herein as the “operating distance” of the power transmitter 11, 110, 112. In this scenario, the power receiver 120 coincides with, or coincides approximately with, the beam waist of outgoing beam 135A, 135. Upon return by the power receiver 120, the incoming beam 135B, 135D diverges towards the power transmitter 110, 112. Here, the outgoing beam 135A, 135C converges and the incoming beam 135B, 135D diverges in an opposite manner. The beam width of incoming beam 135B, 135D received at the power transmitter 110, 112 is approximately the same as the beam width of the outgoing beam 135A, 135C transmitted at the power transmitter 110, 112.

[0101] In another scenario (not shown), where the power receiver 120 is located closer than the target maximum range, the outgoing beam 135 A, 135C is still converging when received by the power receiver 120. Upon return by the power receiver 120, the incoming beam 135B, 135D continues to converge, at least initially, towards the power transmitter 110, 112. The beam width of incoming beam 135B, 135D received at the power transmitter 110, 112 is smaller than the beam width of the outgoing beam 135A, 135C transmitted at the power transmitter 110, 112.

[0102] In one or more alternative embodiments, as illustrated in FIGs. 4C and 4D, the power transmitter 110, 112 is configured to diverge the outgoing beam 135 A, 135C, at least initially. Identical and like elements of between FIGs. 4A and 4B and FIGs. 4C and 4D are labelled with identical and like references, respectively. In this scenario, the power transmitter 110, 112 coincides with, or coincides approximately with, the beam waist of outgoing beam 135A, 135. Upon return by the power receiver 120, the incoming beam 135B, 135D is converged towards the power transmitter 110, 112. For example, the power receiver 120 may include converging optics to converge the incoming beam 135B, 135D. The converging optics may include one or more lenses, such as focussing lens(es) and / or de-focussing lens(es). Here, the outgoing beam 135A, 135C diverges and the incoming beam 135B, 135D converges in an opposite manner. The beam width of incoming beam 135B, 135D received at the power transmitter 110, 112 is approximately the same as the beam width of the outgoing beam 135A, 135C transmitted at the power transmitter 110, 112. In some cases, the converging optics may be dynamically adjusted. For example, the dynamic adjustment may be to adjust the beam convergence of the incoming beam 135B, 135D such that the beam waist coincides or approximately coincide with the power transmitter 110, 112. Adjustment to the beam convergence may be based on the beam width of the outgoing beam 135A, 135C received at the power receiver 120, 122. For example, a greater received beam width at the power receiver 120, 122 corresponds to an adjustment of a greater convergence. The adjustment of the beam convergence may be by way of repositioning of the one or more lenses, such as by mechanical actuation (e.g. one or more stepper motors). The adjustment of the beam convergence allows for dynamic re-focussing of the incoming beam 135B, 135D. Alternatively or additionally, the adjustment of the beam convergence may be way of controlling one or more fluidic adaptive lenses, such as based on pressure actuation, using for example one or more pressure actuators.

[0103] In one or more alternative embodiments, the power receiver 12, 120 is configured to reflect a plurality of beamlets of the safety beam 404, as described in the Applicant’s co-pending applications.

[0104] In one or more embodiments, the safety beam 402 may be axially aligned with the power beam 404, as shown in subsets (a) and (b) of FIGs. 4A-4D. For example, the safety beam 402 and the power beam 404 may share, along at least a portion of either beam, a common optic axis 412. Alternatively, the safety beam 402 may be axially mis-aligned with the power beam 404, while still wholly encompassing the power beam 404 (at least over the operating distance). In either case, the safety beam 402 can be described as “encompassing” the power beam 404 (at least over the operating distance). The safety beam 402 may have, or may be configured to have, a larger beam diameter than the power beam 404 along at least a portion of the constituent beams 402, 404, whether axially aligned or axially misaligned. For example, the safetybeam 402 has a larger beam diameter than the power beam 404 along all portion of the constituent beams 402, 404. The safety beam 402 and power beam 404 may each have circular beam shape, as illustrated in FIGs. 4A-4D. Alternatively, the safety beam 402 and power beam 404 may each have a beam shape other than circular, such as elliptical (not shown). In case of an elliptical beam shape, the diameter of the safety beam may be larger than that of the power beam in both axes.

[0105] The safety beam 402, having a larger diameter than the power beam 404, provides a spatial buffer 406 around the power beam 404. The spatial buffer 406 allows for detection of obstacle intrusion into the light path of the outgoing beam 135A, 135C before breaching the power beam 404. In cases where the safety beam 402 and power beam 404 are axially misaligned and / or have different beam profdes, the safety beam 402 can be configured with a beam diameter sufficiently larger than a beam diameter of the power beam 404 such that, at all positions, at least within the operating distance, there is at least a predefined minimum distance (e.g., corresponding to the spatial buffer 406) between the safety beam 402 and the power beam 404. Referring to FIGs. 4B and 4D, corresponding to the scenario in FIGs. 4A and 4C, respectively, where an obstacle 408 (e.g. a bird, dust cloud, an aircraft) enters the light path of outgoing beam 135A, 135C, the obstacle 408 first enters the light path of the safety beam 402, before potentially entering the light path of the power beam 404. The initial entry of the obstacle 408 into the light path of the safety beam 402 allows the present power beaming system to react before the obstacle 408 makes entry (or further entry) into the light path of the power beam 404. As described in the Applicant’s co-pending applications, the size of the spatial buffer can be determined, at least in part, in accordance with a defined set of operational parameters, such as in accordance with a defined standard. For example, the size of the spatial buffer can be determined, at least in part, in accordance with a maximum expected relative speed of a foreign object (e.g., relative to the power transmitter 12, 120) that risks intercepting the power beam 404 and a maximum allowed reaction time between detection of such an object using the safety beam 402 and taking suitable action (e.g., typically disabling the power beam 404 or at least reducing the output intensity of the power beam 404 below a safety-related threshold).

[0106] Where an obstacle at least partially blocked the outgoing beam 135A, 135C, a shadow region 410 is created. The shadow region 410 corresponds to periphery of the safety beam 402. The blocked periphery of the safety beam 402 in turn corresponds to a decrease in power of the safety beam 402 upon return. Therefore, light at the first wavelength (i.e., the safety beam 402) reaching the power receiver 120 and returned to the power transmitter 110 is at least reduced or at worst not received. The decrease in return power of the safety beam 402 is such that the decrease is detectable by the photodetector. The transmitter controller 114 is configured to determine a defined change, such as a defined percentage change over adefined duration, in return power of the safety beam 402, based on detection by the photodetector. Accordingly, based on reduction or non-receipt of the return light received at the power transmitter (e.g. the one that is active in providing power), transmitter controller 114 may influence operation of the present power beaming system, such as ceasing light transmission of the power transmitter to address obstacle intrusion.

[0107] In some cases, the shadow region 410 additionally corresponds to periphery of the power beam 404. However, any peripheral power being blocked in the power beam 404 is designed to be negligible or lower than required by safety standards. For example, the spatial buffer 406 may be adjusted in size to contain the peripheral power blockage in the power beam 404. For a given a detectable decrease in the power of the safety beam 402, a larger spatial buffer 406 corresponds to a smaller (hence safer) peripheral power blockage in the power beam 404.

[0108] In embodiments, the size of the spatial buffer 406 may be adjusted based on tolerance of obstacle intrusion. A larger spatial buffer 406 allows for more sensitive detection of obstacle intrusion. In other words, a larger spatial buffer 406 allows for a larger shadow region 410 (or a smaller periphery) before the power beam 404 is, or is significantly, breached. However, the size of the spatial buffer 406 may be limited by the numerical aperture of the power receiver and / or sensitivity of the photodetector.

[0109] To adjust the size of the spatial buffer 406, the system 10, 100, 112 may include beam shaping optics for beam shaping the outgoing optical beam 135 A, 135C, which can include in whole or in part beam shaping the safety beam 402 and the power beam 404 separately. Beam shape may include any one or more of: beam size, beam diameter, and beam ellipticity. Beam size is a measure of the area occupied by an optical beam. Beam diameter is a measure of the transverse extent of the optical beam in one or both longitudinal dimensions (e.g. x and / or y). Beam ellipticity is the ratio of the radial extent between the longitudinal dimensions (e.g. x and y) of the optical beam. Each of beam size, beam diameter and beam ellipticity may be quantified based on the full -width at half maximum (FWHM). Further, beam shape of the constituent safety and power beams 402, 404 may be separately adjustable. To separately adjust the beam shape for the constituent safety and power beams 402, 404, the beam shaping optics may include a first set of optics for beam shaping the safety beam 402, and a second set of optics for beam shaping the power beam 404. The beam shapes may be adjustable by adjusting relative positions of optical elements of the beam shaping optics. The relative positions of the optical elements may be adjustable by way of mechanical actuation, for example, by one or more stepper motors. For example, the beam shaping optics includes one or more beam expanders or compressors to increase a beam diameter. A beam expander or compressor includes two converging lenses, longitudinally separated based on a desired magnificationfactor. The longitudinal separation may be adjusted by way of the above-mentioned mechanical actuation. As another example, the beam shaping optics includes one or more beam ellipticity adjustors. A beam ellipticity adjustor includes the same of different set of two converging lenses, axially offset by a defined offset based on desired ellipticity. The axial offset may be adjusted by way of the above-mentioned mechanical actuation.

[0110] As mentioned, transmitter controller 114 is configured to determine any changes in the return light, for example changes in the amount of return light. In the following examples, it is assumed that the transmitter controller 114 is configured to determine that there is a 1% drop in safety beam 402 power detected by the photodetector:

[0111] As a first example, the safety beam 402 may have an at least 1.25 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and power beam 404 are axially aligned and having a Gaussian beam profile with 1 / 2half-widths of a and more than 1.25c, respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 2.91c of the centre of the aligned beams 402, 404, at which point the power beam power will drop by less than 0.18%, which may be absorbed by the obstacle and / or scattered to the surroundings.

[0112] As a second example, the safety beam 402 may have an at least 1.5 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and the power beam 404 are axially aligned and having a Gaussian beam profile with / g2half-widths of c and more than 1.5 c, respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 3.49c ofthe centre of the aligned beams 402, 404, at which point the power beam power will drop by less than 0.024%, which may be absorbed by the obstacle and / or scattered to the surroundings.

[0113] As a third example, the safety beam 402 may have an at least 1.75 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and the power beam 404 are axially aligned and having a Gaussian beam profile with / g2half-widths of c and more than 1.75 c, respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 4.07c ofthe centre of the aligned beams 402, 404, at which point the power beam power will drop by less than 0.00235%, which may be absorbed by the obstacle and / or scattered to the surroundings.

[0114] As a fourth example, the safety beam 402 may have an at least 2 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and the power beam 404 areaxially aligned and having a Gaussian beam profile with / g2half- widths of o and more than 2 a. respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 4.65a of the centre of the aligned beams 402, 404, at which point the power beam power will drop by less than 0.00016%, which may be absorbed by the obstacle and / or scattered to the surroundings.

[0115] As a first example, the safety beam 402 may have an at least 2.25 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and the power beam 404 are axially aligned and having a Gaussian beam profile with 1 / 2half-widths of o and more than 2.25a, respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 5.23a ofthe centre of the aligned beams 402, 404, at which point the power beam power will drop by less than 0.0000084%, which may be absorbed by the obstacle and / or scattered to the surroundings.

[0116] As a sixth example, the safety beam 402 may have an at least 2.5 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and the power beam 404 are axially aligned and having a Gaussian beam profile with / g2half-widths of o and more than 2.5a, respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 5.82a ofthe centre of the aligned beams 402, 404, at which point the power beam power will drop by less than 0.000000295%, which may be absorbed by the obstacle and / or scattered to the surroundings.

[0117] As a seventh example, the safety beam 402 may have an at least 3 times larger beam diameter than the power beam 404. In this case, assuming that the safety beam 402 and the power beam 404 are axially aligned and having a Gaussian beam profile with / g2half- widths of o and more than 3 a, respectively, the safety beam power will drop by 1% if an obstacle intrudes within about 9.3 a of the centre of the aligned beams 402, 404, at which point the power beam power will drop by a negligible amount.

[0118] In an embodiment, the outgoing beam generator 118 of at least one power transmitter 11, 110, 112 comprises a multi-wavelength source (not shown) configured to generate both light at the first wavelength and light at the second wavelength (i.e., the multi-wavelength source is configured to generate both the safety beam 402 and the power beam 404).

[0119] Referring to FIG. 10, in an embodiment, at least one power transmitter 11, 110, 112 comprises two or more distinct light generators 210, 220. In the example shown, and assumed herein, two distinct light generators 210, 220 are utilised: a first light generator 210 (herein also referred to as a “safety beam generator 210”) for generating light at the first wavelength (i.e., the safety beam 402); and a second lightgenerator 220 (herein also referred to as a “power beam generator 220”) for generating light at the second wavelength (i.e., the power beam 404).

[0120] As shown in the figure, practically, the use of multiple distinct light generators 210, 220 inherently results in the safety beam 402 and power beam 404 initially being unaligned; for example, the safety beam 402 as emitted by the safety beam generator 210 is non-parallel to and / or does not share a common axis with the power beam 404 as emitted by the power beam generator 220.

[0121] The safety beam generator 210 is optically coupled to a safety beam shaping mechanism 212, configured to perform beam shaping of the safety beam 402 before the safety beam 402 is combined with the power beam 404. In the example shown, the safety beam shaping mechanism 212 is integral with the safety beam generator 210 (e.g., safety beam shaping mechanism 212 comprises, for example, one or more optical lenses provided within an enclosure of the safety beam generator 210). However, in other implementations, the safety beam shaping mechanism 212 can comprise, in part or in whole, optical components separately provided to the safety beam generator 210. Similarly, the power beam generator 220 is optically coupled to a power beam shaping mechanism 222, configured to perform beam shaping of the power beam 404 before the power beam 404 is combined with the safety beam 402. In the example shown, the power beam shaping mechanism 222 is integral to the power beam generator 220, however, in other implementations, the power beam shaping mechanism 222 can comprise, in part or in whole, optical components separate to the power beam generator 220.

[0122] The at least one power transmitter 11, 110, 112 includes an optical combiner 230 configured to combine the outputs of the two or more distinct light generators 210, 220 together; for example, combining the safety beam 402 as emitted by the safety beam generator 210 and the power beam 404 as emitted by the power beam generator 220 to thereby provide the outgoing optical beam 135A, 135C (in cases where both the safety beam 402 and power beam 404 are emitted.. The optical combiner 230 is therefore configured to align the safety beam 402 and the power beam 404 such as to attain the necessary alignment of the two beams 402, 404 as described herein. For example, the optical combiner 230 may include one (or more) of the following: a beam splitter, dichroic mirror, and a wavelength-division multiplexer.

[0123] In embodiments, the optical combiner 230 comprises a dichroic mirror 232, for example a dielectric mirror, selected such as to transmit substantially all of either the safety beam or the power beam, and to reflect substantially all of the other of the safety beam and the power beam. In the embodiment shown in FIG. 10, the dichroic mirror 232 is selected to have a high reflectivity for the power beam 404 such as to act as a high efficiency mirror in respect of light incident onto it from the power beam generator220. The dichroic mirror 232 is also selected to have a high transmittance for the safety beam 402, such that substantially all of the safety beam 402 passes through the dichroic mirror 232 without reflection.

[0124] In a general sense, the optical combiner 230 acts to align the safety beam 402 and the power beam 404, thereby forming a combined beam 420. Typically, the combined beam 420 is modified before being emitted from the power transmitter 11, 110, 112 as the outgoing optical beam 135 A, 135C, although an embodiment is envisaged in which no further modification of the combined beam 420 is required.

[0125] In one or more embodiments, the physical positions and orientations of the pre-combiner optical components 210, 212, 220, 222, 230 with respect to one another is such that, the safety beam 402 after transmission through the optical combiner 230 (e.g., dichroic mirror 232) is aligned with the power beam 404 after reflection by the dichroic mirror 232. Here, “pre-combiner optical components” refers to the safety beam generator 210, the safety beam shaping mechanism 212, the power beam generator 220, the power beam shaping mechanism 222, and the optical combiner 230 itself (e.g., in the embodiment of FIG. 10, being the dichroic mirror 232). The pre-combiner optical components 210, 212, 220, 222, 230 can be understood to collectively act such as to generate, as an output, the combined beam 420.

[0126] According to at least one embodiment, one or more of the pre-combiner optical components 210, 212, 220, 222, 230 comprises an alignment mechanism 234, enabling fine adjustment of the relative position and / or orientation of the relevant component with respect to the other pre-combiner optical components 210, 212, 220, 222, 230. Typically, at least two of said pre-combiner optical components 210, 212, 220, 222, 230, and optionally all, are associated with an alignment mechanism 234. Two pre-combiner optical components 210, 212, 220, 222, 230 can share the same alignment mechanism 234, for example, the safety beam generator 210 and safety beam shaping mechanism 212 can share at least one common alignment mechanism 234, which can be particularly applicable where these are integrated with one another. Similarly, for example, the power beam generator 220 and power beam shaping mechanism 222 can share a common alignment mechanism 234 (where applicably, typically different to the common alignment mechanism 234 of the safety beam generator 210 and safety beam shaping mechanism 212), which again can be particularly applicable where these are integrated with one another.

[0127] Typically, a particular power transmitter 110 is calibrated before being put into operation, for example, as part of a manufacturing process. Such calibration can include utilising the one or more alignment mechanisms 234 to adjust the relative positions and / or orientations of the various pre-combiner optical components 210, 212, 220, 222, 230 with respect to one another, after the pre-combiner optical components 210, 212, 220, 222, 230 have been physically affixed to the mounting board 240. Calibrationcan be undertaken, at least in part, by a user such as a suitably trained technician. Calibration can also, at least in part, be automated (for example, via robotic means for adjusting one or more alignment mechanisms 234. Calibration can include measuring at least one measurable parameter of the outgoing optical beam 135A, 135C and adjusting the one or more alignment mechanisms 234 until said measurements indicate alignment of the safety beam 402 and the power beam 404 within predefined tolerances.

[0128] An alignment mechanism 234 typically comprises means for locking its associated pre-combiner optical component(s) 210, 212, 220, 222, 230 into place, once calibration is completed, such that the relative positioning of the associated pre-combiner optical components 210, 212, 220, 222, 230 with respect to the other pre-combiner optical components 210, 212, 220, 222, 230 is physically fixed.

[0129] As described herein, during operation, the power transmitter 110 is controlled such as to direct the safety beam 402 and, when activated, the power beam 404, towards a target power receiver 120. The power receiver 120 is associated with an aerial vehicle 150 which can be located at an arbitrary position within the airspace around the power transmitter 110. Therefore, the direction at which the safety beam 402 and power beam 404 are pointed is changeable.

[0130] Advantageously, as the pre-combiner optical components 210, 212, 220, 222, 230 are fixed in position with respect to the same mounting board 240, the relative positions and orientations of the precombiner optical components 210, 212, 220, 222, 230 are maintained as the outgoing optical beam 135A, 135C is emitted in different directions. In embodiments, the mounting board 240 itself is caused to rotate, thereby causing rotation of the pre-combiner optical components 210, 212, 220, 222, 230.

[0131] Still referring to FIG. 10, in one or more embodiments, one or more additional optical components 250, 252 are located after the optical combiner 230 in the beam path, referred to herein as “post-combiner optical components”. The one or more post-combiner optical components 250, 252 act on the combined beam 420, and therefore act equivalently on both the safety beam 402 and the power beam 404.

[0132] Advantageously, therefore, the relative arrangement of the one or more pre-combiner optical components 210, 212, 220, 222, 230 and the one or more post-combiner optical components 250, 252 remain fixed in relative positions and orientations with respect to one another, irrespective of movement of the mounting board 240. Similarly to the pre-combiner optical components 210, 212, 220, 222, 230, the one or more post-combiner optical components 250, 252 can be associated with one or more alignment mechanisms 234, enabling a user, such as a qualified technician, to alter and lock in place the relativepositions and / or orientations of the one or more post-combiner optical components 250, 252, with respect to the mounting board 240 (e.g., during calibration).

[0133] Referring to FIG. 10, in one or more embodiments, a combined beam shaping mechanism 250 is provided, corresponding to a post-combiner optical component. The combined beam shaping mechanism 250 is configured to shape the combined beam received from the optical combiner 230. For example, the combined beam shaping mechanism 250 comprises a collimating mirror, such as a 4 inch off-axis parabolic mirror with a 508 mm focal length.

[0134] Still referring to FIG. 10, in one or more embodiments, a fine-steering mechanism 252 is provided, corresponding to a post-combiner optical component. The fine-steering mechanism 252 is located after the optical combiner 230. The fine-steering mechanism 252 can be located after the combined beam shaping mechanism 250, as is the case in the illustrated embodiment. The fine-steering mechanism 252 enables control over the direction at which the combined beam is emitted from the power transmitter 110, within a limited range, without requiring movement of the mounting board 240. For example, the fine- steering mechanism 252 can comprise a piezoelectric mirror (e.g., 101.6 mm fine-steering fused silica mounted on a piezoelectric actuator).

[0135] Advantageously, therefore, the relative arrangement of the one or more pre-combiner optical components 210, 212, 220, 222, 230 and the one or more one or more post-combiner optical components 250, 252 remain fixed irrespective of movement of the mounting board 240. The one or more post-combiner optical components 250, 252 can be associated with one or more alignment mechanisms 234, enabling a technician (e.g., during calibration) to alter and lock in place the relative positions and / or orientations of the post-combiner optical components 250, 252, with respect to the mounting board 240.

[0136] Advantageously, as the safety beam 402 and the power beam 404 are already aligned due to the action of the pre-combiner optical elements 210, 212, 220, 222, 230, the one or more post-combiner optical components 250, 252 act the same on both. Therefore, due to the physically secured relationship between the various optical components 210, 212, 220, 222, 230, 250, 252, the action of the post-combiner optical components 250, 252 on the safety beam 402 is the same, or sufficiently similar, to the action of the postcombiner optical components 250, 252 on the power beam 404.

[0137] As a result of the various optical components 210, 212, 220, 222, 230, 250, 252 being physically locked with respect to the mounting board 240 and therefore to one another, an advantage of embodiments such as that shown in FIG. 10 can be that the safety beam 402 is physically constrained to alwaysencompass the power beam 404, at least within the operating distance. Furthermore, the relative position of the power beam 404 within the safety beam 402 is also consistent.

[0138] In at least one embodiment, the mounting board 240 is formed from a suitably sturdy material (including composite materials) to resist deformations during operation large enough to adversely affect the performance of the composite beam. For example, temperature induced deformation should be small, at least over the range of expected changes in operating temperature for the power transmitter 11, 110, 112, such that any relative movement of the optical components 210, 212, 220, 222, 230, 250, 252 with respect to one another is insufficient to cause the relative alignment of the safety beam 402 and power beam 404 to fall outside of the required alignment, within predefined operating tolerances. In an example, a CarbonVision Optomechanical Carbon Fibre Breadboard was utilised as the mounting board 240, which may produce less than a one micro-radian deviation in the relative positioning of the components during operation of the power transmitter 11, 110, 112.

[0139] In one or more embodiments, the mounting board 240 and optical components 210, 212, 220, 222, 230, 250, 252 are located within an environmentally controlled housing, in order to reduce changes in the ambident environment of the mounting board 240 and optical components 210, 212, 220, 222, 230, 250, 252, such as changes in temperature, humidity, and other environmental factors, during operation of the power transmitter 11, 110, 112. In this way, advantageously, deformations and other causes of changes in the relative positions and orientations of the optical components 210, 212, 220, 222, 230, 250, 252 due to environmental factors can be reduced. For example, the housing can be dry-air purged to offer protection against deviations due to thermal expansion and / or thermal blooming due to water vapour. Also, in one or more embodiments (not shown), a cooling system is provided in order to actively control and mitigate against significant fluctuations in the ambient temperature within the housing.

[0140] Described embodiments of the power beaming system 10, 100, 102 according to the present disclosure are suited for implementing one or more power beaming methods, which will now be described. For example, one or more embodiments can comprise one or more of the following power beaming methods can be directed to the three distinct operating phases of the power beaming system: (a) a method 500 for operating a power beaming system, which relates to regular operations of the power beaming system, (b) an initialisation method 600 for a power beaming system, which relates to the initial operations of the power beaming system, and (c) an interlocking method 700 for a power beaming system, which relates to the interlocking operations of the power beaming system.

[0141] FIG. 10 also shows a camera arrangement 260 that can be incorporated onto the mounting board 240 (depending on the embodiment). The camera arrangement 260 can correspond, at least in part, to the visual targeting hardware described below in relation to the passive subsystem 166.

[0142] FIG. 5 is a flowchart that depicts a method 500 for operating a power beaming system, such as the power beaming system 10, 100, 102, according to some embodiments of the present disclosure. The method 500 corresponds to the power beaming system 10, 100, 102 operating under continuing conditions, such as in the midst of delivering wireless power. The method 500 includes the steps of: (a) transmitting 510, by a power transmitter 11, 110, 112, an optical beam 135A, 135C, the optical beam 135A, 135C including light at a first wavelength (i.e., a safety beam 402) and light at a second wavelength (i.e., a power beam 404), distinct from the first wavelength; (b) (i) receiving 520, by a power receiver 12, 120 including wavelength discriminator 130, the optical beam 135A, 135C, (ii) returning 522 the transmitted light at the first wavelength for receipt by the power transmitter (i.e., the incoming optical beam 135B, 135D comprises a reflected portion of the safety beam 402), and (iii) 524 accepting, at the power receiver 12, 120, the transmitted light at the second wavelength for optical-to-electrical power conversion (i.e., the power beam 404 is substantially accepted at the power receiver 12, 120); and (c) influencing 530 operation, by one or more processors, of a power beaming system 10, 100, 102, based on the return light received at the power transmitter 11, 110, 112.

[0143] The method 500 may include performing further steps or actions, in correspondence with the embodiments described in respect of the power beaming system 10, 100, 102. For example, where embodiments of the power beaming system 10, 100, 102 are configured to cease transmission of light based on a predetermined condition, the power beaming safety method 500 may perform corresponding steps or actions, such as ceasing transmission of light (e.g., ceasing transmission of the power beam 404) based on the predetermined condition. As another example, where embodiments of the power beaming system 10, 100, 102 are configured to provide a spatial buffer by way of a safety beam 402 around a power beam 404, the power beaming safety method 500 may perform corresponding steps or actions, such as providing the spatial buffer by way of the safety beam 402 around the power beam 404.

[0144] FIG. 6 is a flowchart that depicts an initialisation method 600 for operating a power beaming system, such as the power beaming system 10, 100, 102, according to some embodiments of the present disclosure. The initialisation method 600 corresponds to the power beaming system 10, 100, 102 operating initially, such as in the lead up to delivering wireless power.

[0145] The initialisation method 600 includes the steps of: (a) at a power transmitter 11, 110, 112, transmitting 610 a first constituent beam including light at a first wavelength (i.e., a safety beam 402); (b) at a power receiver 12, 120„ via a wavelength discriminator 130, returning 620 the transmitted light at the first wavelength for receipt at the power transmitter 11, 110, 112; (c) at the power transmitter 11, 110, 112, based on and subsequent to receipt of return light at the first wavelength (e.g., based on a measurement of an intensity of the safety beam 402 received at the power transmitter 11, 110, 112 after reflection at the power receiver 12, 120), commencing 630 transmission of a second constituent beam (i.e., a power beam 404) including light at a second wavelength, distinct from the first wavelength; and (d) at the power receiver 12, 120, via the wavelength discriminator 130, accepting 640 the transmitted light at the second wavelength for optical-to-electrical power conversion.

[0146] Before the step of transmitting a second constituent beam including light at a second wavelength, the initialisation method further includes the step of maximizing the receipt of return light at the first wavelength. For example, the method includes maximising the detected intensity of the returned safety beam 402 before transmitting the power beam 404.

[0147] In embodiments, the step of transmitting the second constituent beam including light at the second wavelength includes continuing transmission of the first constituent beam including light at the first wavelength (for example, transmission of the safety beam 402 continues after initiating transmission of the power beam 404). The method may further include the step of, at the power transmitter 11, 110, 112, ceasing light transmission at the second wavelength responsive to non-receipt or reduction of the return light at the first wavelength receiving at the power transmitter. For example, the power transmitter 11, 110, 112 is configured such that transmission of the power beam 404 is not possible in a case of non-receipt or reduction of the returned safety beam 402 (i.e., after reflection at the power receiver 12, 120).

[0148] FIG. 7 is a flowchart that depicts an interlocking method 700 for a power beaming system 10, 100, 102, according to some embodiments of the present disclosure. The interlocking method 700 corresponds to the power beaming system 10, 100, 102 operating interruptedly, such as in the lead up to terminating wireless power delivery.

[0149] The method 700 includes the steps of: (a) at a power transmitter 11, 110, 112, transmitting 710 an optical beam including light at a first wavelength and light at a second wavelength, distinct from the first wavelength (i.e., the power beam 404 is being transmitted as well as the safety beam 402); (b) at a power receiver 12, 120, via a wavelength discriminator 130, returning 720 the transmitted light at the first wavelength for receipt by the power transmitter 11, 110, 112, and accepting the transmitted light at thesecond wavelength for optical -to-electrical power conversion (e.g., substantially all of the safety beam 402 is reflected by the wavelength discriminator 130 whereas substantially all of the power beam 404 is accepted by the wavelength discriminator 130); and (c) at the power transmitter 11, 110, 112, responsive to a predetermined condition of the return light at the first wavelength received at the power transmitter 11, 110, 112, 730 ceasing light transmission at the second wavelength. The predetermined condition may include non-receipt or reduction of the return light at the first wavelength receiving at the power transmitter 11, 110, 112.

[0150] According to one or more embodiments, with reference to FIG. 8, the transmitter controller 114 is configured to implement one or more operational subsystems 160-168 (typically a plurality of operational subsystems 160-168, as will be assumed herein), which are each logically interfaced with a safety subsystem 170. The operational subsystems 160-168 are typically logical software components of the transmitter controller 114; that is, the operational subsystems 160-168 are typically implemented, at least in part, by the one or more processors of the transmitter controller 114. Similarly, the safety subsystem 170 is typically a logical software component of the transmitter controller 114 and is can therefore be implemented, at least in part, by the one or more processors of the transmitter controller 114.

[0151] The safety subsystem 170 is configured to monitor current operational outputs of each of the operational subsystems 160-168. Here, a “current operational output” of a particular operational subsystem 160-168 refers to data generated, obtained, or otherwise associated with the particular operational subsystem 160-168 and which represents some part of the operation of the power beaming system 10, 100, 102. Each operational subsystem 160-168 can generate one or more associated operational outputs.

[0152] The safety subsystem 170 is configured to determine whether the current output of any one or more of the operational subsystems 160-168 is indicative of a potential operational error of the power beaming system 10, 100, 102 necessitating disabling and blocking future activation of the power beam 404. In cases where the power beam 404 is not yet activated, the safety subsystem 170 blocks future activation of the power beam 404. Therefore, the safety subsystem 170 is configured to determine whether a current operational status of the system 10, 100, 102 includes at least one blocking status. In a case where at least one blocking status is determined, the safety subsystem 170 is configured to block, or otherwise disallow, activation and continuing operation of the power beam (i.e., the power beam is disabled). In a case where no blocking statuses are determined, the safety subsystem 170 is configured to allow activation and continuing operation of the power beam. It should be noted that actual control of the power beam when activation and continuing operation is allowed is determined separately to the determination by the safety subsystem 170.

[0153] In at least one embodiment, such as that shown in FIG. 8, a flight telemetry operational subsystem (“flight telemetry subsystem”) 160 is provided. The flight telemetry subsystem 160 is configured to obtain, from a receiver controller 122 of a power receiver 12, 120 in data communication with the transmitter controller 114, current telemetry data as measured by the power receiver 120. That is, the telemetry data is generated by the power receiver 120 itself, for example, via the positioning module 126 of the power receiver 12, 120. The telemetry data is communicated, via the wireless communication channel, to the flight telemetry subsystem 160 immediately after it is obtained by the positioning module 126. Here, immediately means with minimal delay, while accounting for inherent processing time and data communication time.

[0154] In an embodiment, an auxiliary telemetry operational subsystem (“auxiliary telemetry subsystem”) 162 is provided. The auxiliary telemetry subsystem 162 receives auxiliary telemetry data to the flight telemetry data utilised by the flight telemetry subsystem 160, for example sensor measurements made by sensors located on the aerial vehicle 150 or power receiver 12, 120. The auxiliary telemetry data is communicated to the auxiliary telemetry subsystem 162 via the wireless communication channel from the receiver controller 122. The auxiliary telemetry data can include data associated with the power receiver 120 (e.g., via one or more sensors arranged for monitoring the power receiver 12) and / or data associated with the vehicle 150 itself. Although described as separate data sources, in practice, telemetry data comprising both the flight telemetry data and the auxiliary telemetry data can be communicated to the transmitter controller 114. Similarly, the flight telemetry subsystem 160 and auxiliary telemetry subsystem 162 can be different functional components of a telemetry subsystem.

[0155] In contrast to the flight telemetry data utilised by the flight telemetry subsystem 162, the auxiliary telemetry data utilised by the auxiliary telemetry subsystem 162 relates to non-positional data, such as measurements made by one or more sensors present on the power receiver 120 and / or the vehicle 150. For example, the auxiliary telemetry subsystem 162 can be configured to receive temperature data associated with either or both of the vehicle 150 and the power receiver 120. In another example, the auxiliary telemetry subsystem 162 can be configured to receive electrical power supply data such as voltage and / or current measurements.

[0156] Both the flight telemetry subsystem 160 and the auxiliary telemetry subsystem 162 utilise telemetry data generated, acquired, or otherwise obtained by the receiver controller 122 which is then communicated, typically via the wireless communication channel.

[0157] In at least one embodiment, such as that shown in FIG. 8, an active detection operational subsystem (“active subsystem”) 164 is provided. The active subsystem 164 utilises the safety beam 402 described with reference to FIGs. 4A-4D, which is controlled to actively illuminate the power receiver 120 as described previously. The active subsystem 160 monitors reflection of the safety beam 402 from the power receiver 12, 120 (e.g., from the dichroic retroreflector 200), and produces a corresponding operational output. Depending on the implementation, the active subsystem 164 can be understood as including monitoring for obstacles 408 present within the safety beam 402 (e.g., an operational output of the active subsystem 164 includes a foreign obstacle present / not present status). The active subsystem 164 can also, or instead, be understood as producing at least one operational output related to measurements of the power receiver 120, for example a measurement of changes of position of power receiver 120, which can include a determination of a velocity of the power receiver 120 (e.g., a velocity relative to the power transmitter 11, 110, 112. In an embodiment, with reference to the Applicant’s co-pending applications, at least one operational output utilises a measurement of the spatially resolved optical power of the reflected incoming optical beam 135B, 135D. For example, an operational output can correspond to, or be derived from, a measurement of changes in the spatial distribution of the incoming optical beam 135B, 135D (e.g., representing a possible misalignment of the outgoing optical beams 135 A, 135C and the power receiver 12, 120 and / or a possible relative movement of the power receiver 12, 120).In at least one embodiment, the active subsystem 164 further utilises measurements of the received outgoing optical beam 135A, 135C made by the power receiver 12, 120 (“receiver beam measurements”). In an embodiment, the receiver beam measurements are communicated to the transmitter controller 114 from the receiver controller 122 via the wireless communication channel. The receiver controller 122 can be interfaced with a photodetector for measuring the optical power of the safety beam 402, the power beam 404, or the combination thereof. The photodetector can comprise one or more photodiodes as already described. Therefore, the receiver beam measurements can correspond to another operational output of the active subsystem 164. The receiver beam measurements are indicative of a stability of the alignment of the outgoing optical beam 135A, 135C.

[0158] In at least one embodiment, such as that shown in FIG. 8, a passive detection operational subsystem (“passive subsystem”) 166 is provided. The passive subsystem 166 utilises one or more sensors of the power transmitter 11, 110, 112 for measuring a current position of the power receiver 120, without utilising directed illumination as is the case with the active subsystem 164. Therefore, such measurements of position without utilising the directed illumination are referred to as “passive measurements”.

[0159] The passive subsystem 166 can be interfaced with visual targeting hardware of the power transmitter 110. It is assumed that the visual targeting hardware comprises at least a first cameraarrangement 260 comprising at least one camera sensor and at least one lens arrangement. Typically, the lens arrangement is configured to provide a telescopic lensing effect such that the camera sensor is provided with a relatively narrow field of view. Relevantly, the visual targeting hardware does not utilise targeted illumination of any component of the power receiver 120. The visual targeting hardware optionally utilises non-targeting illumination (such as a flash), such as to improve the performance of the lens arrangement in low light situations; however, the direction of the non-targeting illumination itself is not utilised for generating the passive measurements. The camera can utilise an RGB sensor or monochrome sensor, as well as sensors sensitive to infrared and / or ultraviolet wavelengths.

[0160] The passive subsystem 166 can utilise object detection functionality to identify the presence of the power receiver 12, 120 within a field-of-view of the visual targeting hardware. Once identified, the power receiver 12, 120 can be monitored by ongoing processing of the output the visual targeting hardware, which can reveal, for example, relative movement of the power receiver 12, 120 with respect to the power transmitter 11, 11, 112. In an embodiment, the power receiver 12, 120 comprises a visually identifiable arrangement of visual elements for facilitating identification of the power receiver 12, 120 by the passive subsystem 166; for example, the power receiver 12, 120 can comprise a known arrangement of light emitting diodes (LEDs).

[0161] The passive subsystem 166 can also, or alternatively, utilise object detection functionality to identify the presence of foreign objects (i.e., objects not associated with the power receiver 12, 120) within a field-of-view of the visual targeting hardware. Once identified, a foreign object can be monitored by ongoing processing of the output the visual targeting hardware, which can reveal, for example, relative movement of the foreign object with respect to the power transmitter 11, 110, 112. For example, an operational output of the passive subsystem 166 can be utilised for detection of movement of one or more foreign objects towards the power receiver 12, 120.

[0162] The passive subsystem 166 is similar to the active subsystem 164 in that it relies upon measurements made by the power transmitter 11, 110, 112 of the power receiver 12, 120 and optionally the vehicle 150. However, the passive subsystem 166 is distinguished from the active subsystem 160 in that it does not utilise illumination of the power receiver 12, 120 by either the safety beam 402 (as with the active subsystem 160) or the power beam 404.

[0163] In at least one embodiment, such as that shown in FIG. 8, a receiver beam measurement operational subsystem 168 is provided.

[0164] The safety subsystem 170 is configured is configured to determine a current control status based on the operational outputs of the interfaced operational subsystems 160-168. The current control status can be determined to comprise one or more blocking statuses; if no blocking status is determined, the current control status is determined to be a nonblocking status. The presence of at least one blocking status has the effect of disabling operation of the power beam 404, whereas when no blocking status is determined, operation of the power beam 404 is allowed. In this way, the safety subsystem 170 can halt or block operation of the power beam 404 such as to override control of the power beam by other components of the transmitter controller 114.

[0165] In an embodiment, the safety subsystem 170 determines one or more operational statuses, wherein each operational status is associated with an operational subsystem 160-168, and determines the current control status at least in part in accordance with the determined one or more operational statuses. Here, an operational status associated with a particular operational subsystem 160-168 corresponds to whether the current one or more operational outputs of the particular operational subsystem 160-168 indicates a situation in which the power beam 404 should be blocked. In this way, if any one or more of the operational statuses indicate that the power beam 404 should be blocked, the safety subsystem 170 determines that the current control status comprises at least one blocking status.

[0166] In an embodiment, the safety subsystem 170 determines one or more combined statuses. A particular combined status is determined in accordance with two or more associated current operational outputs, including at least one operational output of each of at least two operational subsystems 160-168. Typically, a combined status is determined according to a comparison of the associated two or more associated current operational outputs. A combined status can be determined to be a blocking status (or not).

[0167] The safety subsystem 170 can determine that a particular combined status does not correspond to a blocking status when the associated current operational outputs of the combined status indicate consistent flight conditions of the power receiver 120 and the vehicle 150 to which it is located. For example, assuming that the vehicle 150 is hovering roughly in place, both the flight telemetry operational output of the flight telemetry operational subsystem 160 and the passive operational output of the passive operational subsystem 166 should indicate that the vehicle 150 is roughly staying at the same position in space. Furthermore, both the flight telemetry operational output and the passive operational output should indicate consistent variations in position (such as random movements due to atmospheric disturbances) to one another. Assuming that there is such consistency in the flight telemetry operational output and the passive operational output, the associated combined status is determined as not being a blocking status.

[0168] However, a case may exist, for example, where the two or more two or more associated current operational outputs are inconsistent with one another yet individually indicate a correct flight condition. In this case, despite the operational outputs individually not causing determination of a blocking status, the safety subsystem 170 can determine that the combined status determined in accordance with said two or more associated current operational outputs is a blocking status, thereby causing the safety subsystem 170 to block operation of the power beam 404.

[0169] Therefore, in an embodiment, activation of the power beam 404 is only allowed by the safety subsystem 170 in the event that each current operational status and each combined status is determined by the safety subsystem 170 to not indicate a blocking status.

[0170] In an embodiment, with reference to FIG. 11, the transmitter controller 114 implements a redundancy subsystem 180. The redundancy subsystem 180 utilises one or more combined statuses (“transmitter-only combined statuses”) associated with two or more operational statuses that are determined solely by the transmitter controller 114 (“transmitter operational statuses”). A transmitter operational status is not dependent upon data received by the transmitter controller 114 from the receiver controller 122; instead, a transmitter operational status is solely determined by the power transmitter 11, 110, 112. Therefore, the two or more transmitter operational statuses do not include, for example, the telemetry data or auxiliary telemetry data described with reference to the flight telemetry subsystem 160 and auxiliary telemetry subsystem 162. For example, a transmitter-only combined status may monitor a transmitter operational status associated with visual targeting hardware of the power transmitter 11, 110, 112 and a transmitter operational status associated with detection of the reflected safety beam 402 (as reflected from the power receiver 12, 120).

[0171] The redundancy subsystem 180 can operate similarly to the safety subsystem 170 as described herein, and can equivalently be understood, depending on the embodiment, as a function of the safety subsystem 170 rather than a logically separate subsystem. The redundancy subsystem 180 is configured to identify a discrepancy between the two or more transmitter operational statuses, for example, where a first transmitter operational status indicates a first state of the power beaming system 10, 100 and a second transmitter operational status indicates a second state of the power beaming system 10, 100, where the first state and the second state contradict one another (i.e., both the first state and the second state cannot be true). For example, the first transmitter operational status may be reporting a first state indicative of nominal operation of the power beaming system 10, 100 whereas the second transmitter operational status may be reporting a second state indicative of a situation in which the power beam 404 is not to be activated.

[0172] In one or more embodiments, upon determining a discrepancy between two (or more) operational statuses, the redundancy subsystem 180 is configured to assume that at least one of the corresponding operational statuses is due to a fault. Therefore, upon determining said discrepancy, the power beam 404 is disabled (and cannot be enabled); e.g., the redundancy subsystem 180 outputs a blocking status. The redundancy subsystem 180 can be configured to remove the blocking status in response to determining that the discrepancy no longer exists. However, in at least one embodiment, for at least one or more types of discrepancy, the corresponding blocking status cannot be removed without user intervention, as said one or more types of discrepancies are indicative of a potential fault, such as a hardware fault (e.g., incorrect axial alignment of the safety beam 402 and power beam404), in which user inspection of the power transmitter 11, 110, 112 is required.

[0173] As the power beam 404 is generated and emitted by the power transmitter 11, 110, 112, it may be advantageous for the redundancy subsystem 180 to monitor at least one transmitter-only combined status, to ensure that a discrepancy can be identified without reference to an external component (such as a power receiver 12, 120, 122). Advantageously, the risk of an operational status erroneously reporting nominal operation (i.e., such that the operational status indicates the power beam 404 can be activated) is mitigated, as a second operational status correctly reporting that the power beam 404 should not be activated effectively overrides the erroneous operational status.

[0174] Referring to FIG. 9, according to one or more embodiments, a multi-stage startup method is utilised.

[0175] At step 900, the transmitter controller 114 receives a power transfer request communicated from a receiver controller 122 of a nearby power receiver 12, 120. The power receiver 12, 120 itself is installed on an aerial vehicle 150 such as a drone. The power transfer request can be received via the wireless communication channel. In another implementation, a different wireless communication protocol is utilised to that of the wireless communication channel for communicating the power transfer request from the receiver controller 122 to the transmitter controller 114, which may be advantageous where the wireless communication channel is intended as a dedicated channel for telemetry communications.

[0176] In a general sense, the power transfer request can enable the transmitter controller 114 to determine compatibility information associated with the particular power receiver 12, 120. The transmitter controller 114 can thereby determine, from the received compatibility information, whether the particular power receiver 12, 120 is compatible for use with the power transmitter 11, 110, 112.

[0177] The power transfer request can comprise a power receiver identifier (“receiver ID”). In one example, the received ID identifies the specific power receiver 12, 120 (i.e., there is a unique receiver ID for every instance of power receiver 12, 120). Alternatively, the receiver ID can identify a type of power receiver 12, 120 and therefore be the same for different instances of the same type of power receiver 12, 120. The transmitter controller 114 can be configured to determine the compatibility information from the received receiver ID; for example, the transmitter controller 114 can maintain or otherwise have access to a lookup table (e.g., stored in a memory of the transmitter controller 114 or accessed via a data network) from which compatibility information can be determined based no the received receiver ID. Alternatively, the power transfer request can include compatibility information directly.

[0178] At step 901 , as part of an initialisation routine begun due to receipt of the power transfer request, the transmitter controller 114 analyses the power transfer request in order to determine whether the power receiver 12, 120 is compatible with the power transmitter 11, 110, 112. Generally, the transmitter controller 114 is configured to initiate power transfer with the power receiver 12, 120 only upon determining that the power receiver 12, 120 is compatible with, and therefore able to receive power transfer from, the power transmitter 11, 110, 112. In an embodiment, assuming compatibility, the transmitter controller 114 further determines one or more power transfer parameters for controlling at least one aspect of the power transfer operation via the power beam 404.

[0179] At step 902, as part of the initialisation routine, the safety subsystem 170 of the transmitter controller 114 determines that a current operational status comprises an initial blocking status. In effect, the initial blocking status is in place from the beginning of an interaction between a nearby power receiver 12, 120 and the power transmitter 11, 110, 112.

[0180] A sequence of two or more subsequent startup routines follow the initialisation routine. As a general concept, each subsequent startup routine can result in a pass condition or a fail condition. In the event that any of the subsequent startup routines results in a fail condition, the initial blocking status is not removed; that is, the power beam 404 is blocked from operation. Only in the event that each of the subsequent startup routines results in a pass condition is the initial blocking status removed and operation of the power beam allowed by the safety subsystem 170. However, if the safety subsystem 170 determines any other blocking status(es) exist, the power beam 404 operation is blocked irrespective of removal of the initial blocking status. In the embodiment shown in FIG. 9, there are three subsequent startup routines: a flight telemetry startup routine, a passive startup routine, and an active positioning startup routine. Other embodiments may utilise these or different startup routines, or a combination thereof.

[0181] Assuming that the transmitter controller 114 determines, at step 902, that the power receiver 12, 120 is compatible, the transmitter controller 114 proceeds to flight telemetry lock startup routine (step 903). Here, the term “flight telemetry lock” refers to determining a position of the power receiver 122 in space using the flight telemetry data communicated, via the wireless communication channel, from the receiver controller 122 to the transmitter controller 114. Therefore, typically, a handshake or other technique is utilised in order to set up data communication between the receiver controller 122 and the transmitter controller 114 over the wireless communication channel. Once established, the data communication is typically ongoing; the receiver controller 122 continuously communicates flight telemetry data to the transmitter controller 114. In this way, the transmitter controller 114 is continuously provided with “up to date” flight telemetry data of the receiver controller 122.

[0182] The safety subsystem 170 monitors the flight telemetry data during establishment of flight telemetry lock. The safety subsystem 170 is configured to identify, from the flight telemetry data, whether an adverse flight condition exists, which is typically determined in accordance with predefined rules. For example, if the flight telemetry data generated by the power receiver 12, 120 (or the vehicle 150 to which it is attached) is insufficiently stable, the safety subsystem 170 may determined that the flight telemetry data indicates a fail condition. In this case, the method proceeds to failed startup step 940.

[0183] However, assuming that the flight telemetry data does not indicate a fail condition, the safety subsystem 170 determines a pass condition for the flight telemetry lock startup routine, thereby establishing telemetry lock.

[0184] Having established telemetry lock, the transmitter controller 114 proceeds to passive positioning startup routine (step 904). The transmitter controller 114 analyses the received flight telemetry data in order to identify, from the flight telemetry data, a current coarse position of the power receiver 12, 120. The coarse positioning is therefore determined based on measurements made by the receiver controller 122 of the power receiver 12, 120 (e.g., using the positioning module 126), rather than measurements made of the power receiver 120 by the power transmitter 11, 110, 112. The coarse positioning may therefore be referred to as “self-positioning”.

[0185] The transmitter controller 114 then utilises the visual targeting hardware of the power transmitter 11, 110, 112 to locate the power receiver 12, 120. For example, a camera and lens arrangement of the first camera arrangement 260 are moved (e.g., via rotation) such that the lens arrangement is pointed towards the current coarse position of the power receiver 12, 120. If the current coarse position as determined from the flight telemetry data received from the power receiver 12, 120 is accurate, then the camera should detectthe presence of the power receiver 12, 120 within its field-of-view. The detection (or not) of the power receiver 12, 120 by the camera can be considered a passive operational output.

[0186] However, if the power receiver 12, 120 is not detected by the camera, this may be indicative of an inconsistency between the flight telemetry data (i.e., a flight telemetry operational output) and the passive operational output, which may represent a combined status determined by the safety subsystem 170 to be a blocking status. Therefore, in the case of such non-detection by the camera, the passive positioning startup routine results in a fail condition and the method proceeds to step 940. Similarly, if the power receiver 12, 120 is detected by the camera but the position of the power receiver 12, 120 as determined by the visual targeting hardware is inconsistent with the coarse position determined from the flight telemetry data, the safety subsystem 170 can determine a combined status as being a blocking status. Similarly, the passive positioning startup routine results in a fail condition and the method proceeds to step 940.

[0187] In a case where the passive positioning startup routine results in a pass condition, the method proceeds to active positioning startup routine (step 905). The coarse position can be improved using a passive position determined using the visual targeting hardware, thereby producing a current passive position.

[0188] The transmitter controller 114 controls the optical beam 135 A such as to emit the safety beam 402 and not the power beam 404. The safety beam 402 is directed towards to the power receiver 12, 120 according to the current passive position. The transmitter controller 114 monitors a detected reflection of the safety beam 402 received at the power transmitter 11, 110, 112, as described herein (corresponding to an active operational output). The safety subsystem 170 is configured to determine a fail condition in the event that the measured returned safety beam 402 does not satisfy predefined requirements, such as in relation to intensity, intensity stability over time, and / or any other measurement parameters. In this case, the safety subsystem 170 determines a blocking status associated with the active operational output of the active operational subsystem 164 and the active positioning startup routine results in a fail condition. Therefore, the method proceeds to step 940. Similarly to as described with reference to the passive positioning startup routine, one or more combined statuses based on the active operational output and either (or both) of the passive operational output and flight telemetry operational output described above can be determined. In the event of an inconsistency between the active operational output and passive operational output and / or flight telemetry operational output, the safety subsystem 170 determines that the relevant combined output is a blocking output and the active positioning startup routine results in a fail condition. The method therefore also proceeds to step 940.

[0189] Otherwise, the active positioning startup routine results in a pass condition. As the flight telemetry startup routine and the passive startup routine also resulted in pass conditions, the safety subsystem 170 determines (at step 906) that the initial blocking condition is to be removed. Therefore, the power beam 404 is no longer blocked due to the initial blocking condition.

[0190] However, the safety subsystem 170 continues to monitor the various operational outputs, as described herein, and may determine the presence of one or more blocking statuses separately to the initial blocking status, in which case activation and ongoing operation of the power beam 404 is blocked.

[0191] However, assuming that no blocking statuses apply, the method proceeds to power beam ramp up step 907. The power beam 404 is activated initially at a relatively low power. This can allow for the receiver controller 122 to detect the power beam 404 and to make relevant measurements of it. These power beam measurements are continuously communicated to the transmitter controller 114 via the wireless communication channel.

[0192] The safety subsystem 170 continuously monitors the received power beam measurements, which can be interpreted as a power beam operational subsystem 168. The measurements themselves can be interpreted as a power beam operational output of the power beam operational subsystem 168. The safety subsystem 170 can determine an associated blocking status in the event that the power beam operational output indicates a problem with receipt of the power beam. Similarly, the safety subsystem 170 can determine an associated combined status, combining the power beam operational output with one or more other operational outputs. In a case of an inconsistency, the combined status can be determined to be a blocking status, as described herein.

[0193] Assuming, however, that the safety subsystem 170 does not determine a blocking status, the intensity of the power beam 404 is increased over time (e.g., linearly or according to some other relationship, which may preferably be monotonic) until it reaches full transmission intensity, at which point the output intensity is maintained. The safety subsystem 170 can at any stage during (or of course after) ramp up determine that at least one blocking status exists, in which case the power beam 404 is immediately ceased and blocked from further emission.

[0194] An advantage of the method of FIG. 9 may be that multiple factors related to targeting and supply optical energy to the power receiver 12, 120 must be operating correctly and consistently with one another before the power beam 404 is emitted and, furthermore, before it reaches full intensity. In this way, the system 10, 110 is biased towards a safety focused approach. In particular, an advantage of the method of FIG. 9 may be an improvement to the effective isolation of the power beam 404.

[0195] Having now described various embodiments and examples of the present disclosure, it should be apparent that the power beaming systems and methods present the following advantages:• All-optical means of initialising and interlocking power delivery can avoid use of RF feedback, hence avoiding limitations in RF range and interception. • Upon initialisation of power beaming, the optical beam path can be determined as cleared even before power delivery is commenced.• During continuing operation of power beaming, an eye-safe safety beam can provide continuing assurance of a clear path.• If an obstacle intrudes the optical beam path, an interlocking procedure allows rapid shut-off of the optical transmitter, especially where a spatial buffer is provided to protect the power beam from intrusion.

[0196] Those skilled in the art will appreciate that the present disclosure described herein is susceptible to variations and modifications other than those specifically described. For example, parameters such as beam diameters, sampling intervals, and monitoring time window may assume values that are different from what are described or exemplified. All such variations and modifications are to be considered within the scope of the present disclosure the nature of which is to be determined from the foregoing description.

Claims

Claims:

1. A power beaming system comprising: a power transmitter configured to controllably generate an outgoing optical beam, wherein the generated outgoing optical beam is controlled such as to include either or both of: a safety beam component comprising light at a first wavelength, and a power beam component comprising light at a second wavelength; and a transmitter controller configured to: control operation of the power transmitter such as to control generation of the safety beam component and generation of the power beam component, such as to controllably direct the outgoing optical beam towards a target airborne power receiver; implement one or more operational subsystems and a safety subsystem, wherein the, or each, operational subsystem is operably interfaced with the safety subsystem, wherein the, or each, operational subsystem is configured to generate at least one operational output, and wherein the safety subsystem is configured to: monitor the one or more operational outputs of the one or more operational subsystems; determine a current operational status in dependence on the current one or more operational outputs; and control operation of the power beam such that the power beam is disabled when the current operational status is determined to include at least one blocking status.

2. The system of claim 1, wherein at least one operational subsystem is configured to generate an associated operational output dependent upon data received from the power receiver via a wireless data channel.

3. The system of claim 2, comprising a flight telemetry operational subsystem configured to receive flight telemetry data from the power receiver via the wireless data channel, and to generate an associated flight telemetry operational output comprising the flight telemetry data.

4. The system of claim 3, wherein the safety subsystem is configured to determine a blocking status in response to determining, from the flight telemetry operational output, that the flight telemetry data indicates that the current flight of the power receiver fails to satisfy a predefined flight requirement.

5. The system of any one of claims 2 to 4, comprising an auxiliary telemetry operational subsystem configured to receive auxiliary telemetry data from the power receiver via the wireless data channel, and to generate an associated auxiliary telemetry operational output comprising the auxiliary telemetry data.

6. The system of claim 5, wherein the safety subsystem is configured to determine a blocking status in response to determining, from the auxiliary telemetry operational output, that the auxiliary telemetry data indicates that at least one current measurement of the power receiver is indicative of a predefined fault condition.

7. The system of any one of claims 1 to 6, wherein at least one operational subsystem is an active operational subsystem configured to generate an associated operational output based on active measurements made at the power transmitter, wherein the active measurements are of an interaction between the outgoing optical beam and the power receiver.

8. The system of claim 7, comprising at least one active operational subsystem in which the associated active operational output is based on measurement made at the power transmitter of an interaction between the safety beam and the power receiver.

9. The system of claim 8, wherein the safety subsystem is configured to determine a blocking status in response to: determining a non-alignment condition between the safety beam and the power receiver; and / or determining that the current measurement of the interaction between the safety beam and the power receiver is indicative of a threshold likelihood of a foreign object interacting with the safety beam.

10. The system of any one of claims 1 to 9, wherein at least one operational subsystem is a passive operational subsystem configured to generate an associated passive operational output based on passive measurements made at the power transmitter of the power receiver.

11. The system of claim 10, comprising an imaging arrangement, and comprising at least one passive operational subsystem configured to generate an associated passive operational output utilising images of the power receiver captured by the imaging arrangement.

12. The system of any one of claims 1 to 13, wherein the safety subsystem is configured to: determine one or more combined statuses, wherein each combined status is associated with two or more operational outputs and is determined, at least in part, according to a comparison between its associated operational outputs, wherein the current control status is determined by reference to the current one or more operational outputs and the current one or more combined statuses.

13. The system of claim 12, wherein for at least one combined status, a blocking status is determined when at least one of its associated operational outputs indicates a first flight condition of the power receiver and wherein at least one other of its associated operational outputs indicates a second flight condition which is determined, by the safety subsystem, to be inconsistent with the first flight condition.

14. The system of any one of claims 1 to 13, wherein the transmitter controller is configured to implement a startup procedure before activating the power beam, wherein the startup procedure comprises an initialisation routine and a sequence of two or more subsequent startup routines, and wherein the safety subsystem is configured to: during the initialisation routine, determine that the current operational status comprises an initial blocking status before proceeding to a first subsequent startup routine; for each subsequent startup routine: identify at least one associated operational output of the one or more operational outputs, monitor said at least one associated operational output during the subsequent startup, and determine either a pass condition or fail condition for the subsequent startup routine based, at least in part, on the monitoring of said at least one associated operational output; and determine removal of the initial blocking status only upon determining a pass condition for every one of the two or more subsequent startup routines.

15. The system of claim 14, wherein each subsequent startup routine after a first subsequent startup routine is initiated only upon determining a pass condition of a directly preceding subsequent startup routine in the sequence.

16. The system of claim 14 or claim 15 when dependent upon claim 12 or claim 13, wherein, for at least one subsequent startup routine, the safety subsystem is configured to determine either the pass condition or fail condition for the subsequent startup routine based, at least in part, on at least one combined status.

17. The system of any one of claims 1 to 16, wherein at least two operational statuses are transmitter operational statuses, wherein each transmitter operational status is generated without dependence on data received from the power receiver.

18. The system of claim 17, wherein the transmitter controller configured to: implement a redundancy subsystem configured to: monitor at least one combined status being a transmitter-only combined status being a combined status based upon a comparison between two or more transmitter operational statuses; determine a blocking status in response to determining a discrepancy between at least a first transmitter operational status and a second transmitter operational status.

19. The system of any one of claims 1 to 18, comprising the power receiver.

20. A power transmitter for use in a power beaming system, wherein the power transmitter is configured to: controllably transmit an outgoing optical beam, wherein the outgoing optical beam is controlled such as to include either or both of: a safety beam component comprising light at a first wavelength, and a power beam component comprising light at a second wavelength; and control a direction at which the outgoing optical beam is emitted from the power transmitter, wherein the power transmitter comprises a plurality of optical components, including: a safety beam generator for generating the safety beam component; a power beam generator for generating the power beam component; an optical combiner, being optically coupled to the safety beam generator such as to receive the safety beam, and being optically coupled to the power beam shaping generator such as to receive the power beam, wherein the optical combiner is configured to combine the safety beam and the power beam such as to produce, as an output, a combined beam, wherein the safety beam and the power beam are aligned with one another in the combined beam.

21. The power transmiter of claim 20, comprising: a safety beam shaping mechanism optically coupled to the safety beam generator such as to receive the safety beam component generated by the safety beam generator, wherein the safety beam shaping mechanism is configured to optically modify the safety beam before the safety beam is received by the optical combiner; and / or a power beam shaping mechanism optically coupled to the power beam generator such as to receive the power beam component generated by the power beam generator, wherein the power beam shaping mechanism is configured to optically modify the power beam before the power beam is received by the optical combiner.

22. The power transmiter of either claim 20 or claim 21, wherein the optical combiner comprises a dichroic mirror configured to either: substantially reflect the power beam component and to substantially transmit the safety beam component; or substantially reflect the safety beam component and to substantially transmit the power beam component.

23. The power transmiter of any one of claims 20 to 22, wherein the plurality of optical components comprises: a combined beam shaping mechanism configured to receive the combined beam emited by the optical combiner, wherein the combined beam shaping mechanism is configured to optically modify the combined beam, thereby modifying the safety beam component and the power beam component.

24. The power transmiter of claim 23, wherein the combined beam shaping mechanism comprising a focusing element.

25. The power transmiter of any one of claims 20 to 29, wherein the plurality of optical components comprises: a fine-steering mechanism configured to receive the combined beam emited by the optical combiner, wherein the fine-steering mechanism is configured to control, at least in part, a direction at which the combined beam is emited from the power transmiter.

26. The power transmiter of any one of claims 20 to 25, wherein the plurality of optical components are each fixedly located on a mounting board, such that a relative position and / or orientation of each optical component is fixed with respect to the mounting board and thereby to each other optical component.

27. The power beaming system of any one of claims 1 to 19, wherein the power transmitter is according to any one of claims 20 to 36.

28. A method for controlling operation of an outgoing optical beam generated by a power transmitter of a power beam system, comprising: controlling generation of a safety beam component of the outgoing optical beam and a power beam component of the outgoing optical beam, wherein the safety beam component comprises light at a first wavelength and the power beam component comprises light at a second wavelength, such as to controllably direct the outgoing optical beam towards a target airborne power receiver; monitoring one or more operational outputs of one or more operational subsystems, wherein the, or each, operational subsystem is configured to generate at least one operational output; determining a current operational status in dependence on the current one or more operational outputs; and controlling operation of the power beam such that the power beam is disabled when the current operational status is determined to include at least one blocking status.

29. A method for controlling operation of an outgoing optical beam generated by a power transmitter of a power beam system, comprising: controlling generation of a safety beam component of the outgoing optical beam and a power beam component of the outgoing optical beam, wherein the safety beam component comprises light at a first wavelength and the power beam component comprises light at a second wavelength, such as to controllably direct the outgoing optical beam towards a target airborne power receiver; monitoring one or more operational outputs of one or more operational subsystems, wherein the, or each, operational subsystem is configured to generate at least one operational output; determining a current operational status in dependence on the current one or more operational outputs; determining that the current operational status comprises at least one blocking status; and in response, controlling operation of the power beam such that the power beam is disabled.

30. The method of either claim 28 or claim 29, wherein the method is implemented by the transmitter controller of the power beaming system of any one of claims 1 to 19 or 27 or the transmitter controller of the power transmitter of any one of claims 20 to 26.

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