Safe laser power beaming for space

Abstract

An optical power beaming system includes a constellation of power beaming satellites, which each may include a laser, a thermal management system for the laser, shaping optics, steering optics, a local controller for the laser and optics, and a communication system. A central controller may be configured to determine which power beaming satellites of the constellation should beam power to the ground-based power receiver, or the satellites may manage these decisions in a distributed fashion, without a central controller.

Description

Safe Laser Power Beaming for SpaceBackground

[0001] Power beaming is an emerging method of transmitting power to places where it is difficult or inconvenient to access using wires, by transmitting a beam of electromagnetic energy to a specially designed receiver which converts it to electricity. Power beaming systems may be free-space (where a beam is sent through atmosphere, vacuum, liquid, or other non-optically-designed media), or power-over-fiber ("‘PoF”), where the power is transmitted through an optical fiber. The latter may share certain disadvantages with wires in some circumstances, but may also offer increased transmission efficiency, electrical isolation, and / or safety. Free-space power beaming may be more flexible, but it may also offer more challenges for accurate targeting of receivers and avoiding hazards such as reflections and objects intruding on the pow er beam.

[0002] All of the subject matter discussed in the Background section is not necessarily prior art and should not be assumed to be prior art merely as a result of its discussion in the Background section. Along these lines, any recognition of problems in the prior art discussed in the Background section or associated with such subject matter should not be treated as prior art unless expressly stated to be prior art. Instead, the discussion of any subject matter in the Background section should be treated as part of the inventors’ approach to the particular problem, which in and of itself may also be inventive.Summary

[0003] In one aspect, an optical power beaming system may include a constellation of at least three power beaming satellites and a central controller. Each power beaming satellite may include a laser, a thermal management system for the laser, shaping optics configured to shape a beam from the laser, steering optics configured to direct the shaped beam, the steering optics having an accuracy of within 0.8 prad, a local controller configured to control a power level of the laser, the shaping optics, and the steering optics to direct the steered beam toward a ground-based power receiver, wherein an intensity of the steered beam at a first specified distance from the center of the ground-based powder receiver is below a predetermined point source optical safety7threshold, and a communication system. The central controller may be configured to determine which power beaming satellites of the constellation should be beaming power to the ground- based power receiver and to communicate a power level and target location information tothe determined power beaming satellites. The combined power intensity from the determined power beaming satellites at a second specified distance from the center of the ground-based power receiver may be below a predetermined multi-scale exposure curve. The central controller may be configured to determine which second set of power beaming satellites of the constellation should be beaming power to a second ground-based receiver, and to communicate power level and target location information to the second set of power beaming satellites of the constellation

[0004] In another aspect, a distributed optical power beaming system may include a constellation of at least three power beaming satellites. Each power beaming satellite may include a laser, a thermal management system for the laser, shaping optics configured to shape a beam from the laser, steering optics configured to direct the shaped beam, the steering optics having an accuracy of within 0.8 prad, a local controller configured to control a power level of the laser, the shaping optics, and the steering optics to direct the steered beam toward a ground-based power receiver, and a communication system configured to communicate with other power beaming satellites of the constellation. An intensity' of the steered beam at a first specified distance from the center of the ground- based power receiver may be below a predetermined point source optical safety threshold. The local controller may be further configured to determine which other power beaming satellites of the constellation are within a specified acceptance angle of the ground-based power receiver (the "eligible satellites”) and determine whether the total power transmitted from all eligible satellites would exceed a predetermined multi-scale exposure curve at a second specified distance from the center of the ground-based power receiver if all eligible satellites were to beam power at their maximum power levels. If it is determined that the total power transmitted from all eligible satellites at their maximum power levels would not exceed the multi-scale exposure curve, the local controller may direct the local controller to use the maximum laser power level. If it is determined that the total power transmitted from all eligible satellites at their maximum power levels would exceed the multi-scale exposure curve, the local controller may use a reduced laser power selected to be produce a total optical power on the ground-based power receiver at the second specified distance from the center of the ground-based power receiver that does not exceed the predetermined multi-scale exposure curve. A ratio of the reduced laser power to the maximum laser power for each satellite may be approximately equal to a ratio of the predetermined multi-scale exposure curve at the second specified distance from the center of the ground-based receiver to the total power at the second specified distance from thecenter of the ground-based receiver if all eligible satellites were to beam power at their maximum power levels.

[0005] In either of the previous aspects, the intensity of the steered beam at the first specified distance may be below the predetermined point source optical safety threshold as averaged over one second. Communicating the power level and target location information to the determined power beaming satellites may include communicating the power level and target location information using the communication system of each determined power beaming satellite. The steering optics of each power beaming satellite of the constellation have an accuracy of within 0.3 prad. The laser may have a wavelength in the range of about 800 nm to about 1,600 nm. The predetermined multi-scale exposure curve may specify a relationship between viewing area and power level, and the power beaming satellite may be configured to beam power only if the relationship between viewing area and power level would be satisfied for all possible viewing areas within the specified acceptance angle of the ground-based power receiver. The constellation may include twenty, fifty, or two hundred satellites.

[0006] In still another aspect, a power beaming system may include a power receiver, and a plurality of orbital power transmitters. The power receiver may include a plurality' of photovoltaic (PV) cells and may have an acceptance angle of at least 100 mrad and a selected spacing angle. Each power transmitter may include a laser, aiming means for the laser having an accuracy of within 0.8 prad, locating means for determining a position of the power transmitter relative to at least one other power transmitter of the plurality7, and communication means for communicating with at least one other power transmitter of the plurality', or w ith a central controller configured to communicate with multiple transmitters of the plurality. In response to a request for power from the power receiver, each power transmitter may be configured to determine whether it is positioned within the acceptance angle of the pow er receiver, if it is within the acceptance angle of the power receiver, determine whether any other pow er transmitter of the plurality' is close enough to it to appear to be within the spacing angle of the power receiver as viewed by the power receiver, and if no other power transmitter is within the spacing angle as seen by the powder receiver and beaming power to the power receiver, the power transmitter may transmit powder to the powder receiver. The selected spacing angle may be at least 3 mrad or at least 10 mrad. Determining whether any other power transmitter of the plurality is close enough to a power transmitter to appear to be within the spacing angle of the power receiver may include communicating with another power transmitter of the plurality' todetermine whether it is beaming power to the power receiver. Communicating with another power transmitter of the plurality may include relaying communication through the central controller. The aiming means may have an accuracy of within 0.3 prad. The pl urality of power transmitters may include at least three power transmitters, at least ten power transmitters, at least twenty-five power transmitters, or at least fifty power transmitters. If a second power transmitter is within the spacing angle, the communication means may be configured to communicate with the second power transmitter to determine whether it is transmitting power to the power receiver. The communication means may include means for transmitting a signal directly to the second pow er transmitter, or means for transmitting a signal to the central controller for further transmission to the second power transmitter. The central controller may be in orbit or ground-based. The means for determining whether the power transmitter is positioned within the acceptance angle may include a GPS system. The power receiver may have an acceptance angle of at least 250 mrad. The power receiver may include an optical concentrator configured to concentrate received light onto a PV cell. The power receiver may further include a safety system capable of detecting a human in the vicinity of a laser beam and directing the pow er transmitter to shut off the laser beam within one second of detecting the human or within 0.5 seconds of detecting the human. The pow er transmitter may be configured to respond to the direction by shutting off the laser beam. The power receiver may further include a safety system capable of detecting that an amount of transmitted power is missing the receiver and communicating that detection to the power transmitter. The powder transmitter may be further configured to respond to the communication of the detection by shutting off or reducing power of the laser beam.

[0007] In yet another aspect, a power receiver for receiving laser light having a selected wavelength from orbit may include optical concentrating means configured to concentrate the received laser light, the optical concentrating means having an optical aperture and an acceptance angle of at least 100 mrad, a plurality of photovoltaic (PV) cells configured to convert the concentrated laser light to electrical power, power electronics configured to supply the converted electrical power to a load, and a support structure configured to support the optical concentrating means and the plurality' of PV cells, the support structure being further configured to be collapsible for transport and expandable for deployment. The optical concentrating means may be configured to direct the concentrated laser light onto at least a subset of the plurality of PV cells. The support structure may be further configured to tilt the optical concentrating means to allow thelaser light to enter the optical aperture. The power receiver may be configured to receive and to convert laser light simultaneously from a plurality of orbital sources. The acceptance angle of the optical concentrating means may be at least 250 mrad. The power receiver may further comprise a safety system configured to detect laser light that misses the optical aperture, which may be configured to respond to a detection of laser light that misses the optical aperture by sending a message to an orbital source of the laser light indicating that at least some of the laser light is missing the optical aperture. This message may be sent to a central controller for retransmission to the orbital source. The support structure is configured to be inflated for deployment, and a shape of the optical concentrating means may be defined by a shape of the inflated support structure.

[0008] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.Brief Description of Figures

[0009] The drawing figures depict one or more implementations in accordance with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. Furthermore, it should be understood that the drawings are not necessarily to scale.

[0010] Fig. 1 is a schematic diagram of a power beaming transmitter and receiver.

[0011] Fig. 2 is an abstracted diagram of the power beaming transmitter of Fig. 1. showing interrelationships between components of the transmitter.

[0012] Fig. 3 is an abstracted diagram of the power receiver of Fig. 1, showing interrelationships between components of the receiver.

[0013] Fig. 4 is a schematic diagram showing paths of light through the eye.

[0014] Fig. 5 is a plot of maximum exposure limits for three different exposure times for 1,070 nm light.

[0015] Fig. 6 shows a perfectly-dispersed constellation of satellites.

[0016] Fig. 7 is a plot of intensity levels for several beam offsets.

[0017] Fig. 8A and Fig. 8B, which may be collectively referred to herein as Fig. 8, show a randomly distributed constellation of satellites. Fig. 8B enlarges the interior of circle 810 of Fig. 8A in order to show more detail.

[0018] Fig. 9 is a plot of what fraction of its maximum power each satellite could provide while maintaining eye safety if a group of satellites are all transmitting power to the same target.

[0019] Fig. 10 is a flow chart showing a simple logic for selecting which satellites will beam to a receiver.

[0020] Fig. 11 is a schematic showing how beam jitter affects accuracy.

[0021] Fig. 12 is a plot of a calculated amount of scintillation for a power beam from orbit to ground.

[0022] Fig. 13 shows possible concentrator shapes for an array of concentrators.

[0023] Fig. 14 is a schematic diagram of multiple satellites transmitting power to multiple receivers.Detailed Description

[0024] In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well-known methods, procedures, components, and / or circuitry have been described at a relatively high level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. Those of ordinary' skill in the art will nevertheless understand the features of these methods, procedures, components, and / or circuitry and how they may be used in the descriptions below. Other relevant material may be found in other patents and applications as follows:Each of these related applications and patents is incorporated by reference herein to the extent not inconsistent herewith.

[0025] As discussed above, power beaming is becoming a viable method of powering objects in situations where it is inconvenient or difficult to run wires. For example, free-space power beaming may be used to deliver electric power via a ground- based power transmitter to power a remote sensor, to recharge a battery, or to power an unmanned aerial vehicle (UAV) such as a drone copter, allowing the latter to stay in flight for extended periods of time. Power over fiber (PoF) systems usually require optical fiber (or an equivalent) to be run from a power source to a receiver, but may nevertheless provide electrical isolation and / or other advantages over traditional copper wires which carry electricity instead of light.

[0026] It will be understood that the term “light source” is intended to encompass all forms of electromagnetic radiation that may be used to transmit energy, and not only visible light. For example, a light source (e.g., a diode laser, fiber laser, light-emitting diode, magnetron, or klystron) may emit ultraviolet, visible, infrared, millimeter wave, microwave, radio waves, and / or other electromagnetic waves, any of which may be referred to herein generally as “light.” The term “power beam” is used herein interchangeably with “light beam” to mean a high-irradiance transmission, generally directional in nature, which may be coherent or incoherent, of a single wavelength or multiple wavelengths, and pulsed or continuous. A power beam may be free-space, PoF, or may include components of each. For example, a transmitter may transmit a free-space power beam to a receiver surface, which may conduct it as light over an optical fiber to a photovoltaic (PV) cell which converts it to electricity. For the sake of readability, the description may use the term “laser” to describe a light source; nevertheless, other sources such as (but not limited to) light-emitting diodes, magnetrons, or klystrons may also be contemplated unless context dictates otherwise.

[0027] As used herein, the phrase “orbital elements” means a set of eight parameters necessary to fully define an orbital trajectory. Those of ordinary skill in the art will understand that when describing an orbit with orbital elements, typically two describe the size and shape of the trajectory, three describe the rotation of the orbit, one describes the speed of motion, and two describe the position of the body around its orbit along with the epoch time at which this occurs. However, if the epoch time is chosen to be the time at which the position-describing element of choice (e.g., mean anomaly) is equal to some constant (usually zero), then said element can be omitted, meaning that only seven elements may be required in total. Further, the motion-describing variable can be the mass or standard gravitational parameter of the central body (for example, the Earth), which isalready known and does not need to be separately specified for each orbit. Thus, as few as six parameters may be explicitly specified to define an orbital trajectory.

[0028] Angles described herein may be measured in degrees or in radians. In particular, angles may be specified in milliradians (“mrad”) or microradians (“prad”). 100 mrad is about 5.7 degrees.

[0029] For many applications, a power receiver is arranged to receive the free- space or PoF power beam and convert it to electricity, for example using PV cells or other components for converting light to electricity (e g., a rectenna for converting microwave power or a heat engine for converting heat generated by the light beam to electricity). For the sake of readability, this application may refer to “PV cells'’ with the understanding that other components having a similar function (such as but not limited to those listed above) may be substituted without departing from the scope of the application.Power beaming systems

[0030] Fig. 1 is a schematic diagram of a power beam transmitter 102 and receiver 104. Laser 106 directs a power beam 108 (shown throughout the diagram as a dotted line) toward optics unit 110, which directs the beam to a beam steering assembly, such as mirror assembly 112. Optics unit 110 may include various lenses, mirrors, and other optical elements, as further discussed below. Steering mirror assembly 112 directs power beam 108 to power receiver 104. Optional chiller 114 is shown as connected to laser 106, but other components of transmitter 102 may also have independent or connected thermal management systems as required. Also shown in Fig. 1 as part of transmitter 102 are tracking system 116 and safety system 118. These systems are shown as being internal to optics unit 110 in the figure, but those of ordinary skill in the art will recognize that in some implementations, they may be external to optics unit 110, part of steering mirror assembly 112, or elsewhere in the transmitter system. Also shown are TX controller 120. user interface 122 and TX communication unit 124, all of which are further discussed below in connection with Fig. 2. It will be understood that transmitter 102 may include other elements, such as beam shapers, guard beams, or other appropriate accessory elements, that have been omitted from Fig. 1 for the sake of simplicity of the illustration. Some of these elements are shown schematically below in Fig. 2, but those of ordinary skill in the art will understand how to combine optical and control elements in a power transmitter.

[0031] Receiver 104 includes a PV array 130, which includes a plurality of individual PV cells 132 (not all PV cells are labeled in order to avoid unnecessarily cluttering the figure). PV cells 132 convert incoming power beam 108 into electricity7as further described below. Receiver 104 also shows tracking emitters 134, which in some implementations may be used by the tracking system 116 to monitor the position of PV array 130 for beam tracking or for other purposes. Receiver 104 also shows safety emitters 136, which in some implementations may be used by safety system 118 to monitor power beam 108 for potential intrusions, reflections, or other safety hazards. RX (receiver) communication unit 138 is in communication with TX communication unit 124 (as indicated by the dashed line), and may be used for safety, tracking, telemetry7, feedback control, or any other purpose for which it may be desirable for transmitter 102 and receiver 104 to communicate. While the illustrated embodiment provides communication across a separate channel such as a radio link between transmitter 102 and receiver 104, it is also contemplated that communication may be accomplished via modulation of power beam 108, tracking emitters 134, safety emitters 136, or other existing components of the power beaming system. Receiver 104 may also include optional RX sensors 140. further described below in connection with Fig. 3. As shown in Fig. 1, PV array 130 is mounted on optional mast 142, which may elevate receiver 104 to allow power beam 108 to avoid humans or other obstacles.

[0032] Fig. 2 is an abstracted diagram showing functional relationships between components of the transmitter. Transmitter 102 includes a laser 106, but it will be understood that other light-generating components, such as an LED or a magnetron, may be substituted for laser 106 in some implementations. Laser 106 is connected to controller 120. power supply unit (PSU) 202 (which is in turn connected to input power 204), and a thermal management system (chiller) 114. Throughout Fig. 2 and Fig. 3, heat flow is denoted by heavy dotted lines, while power beam 108 is denoted by a heavy solid line, sensor signals are denoted by heavy dashed lines, data and / or control signals are denoted by dot-dashed lines, and electrical power is indicated by a thin solid line. For the sake of clarity, not all internal electrical connections are shown.

[0033] Controller 120 controls operation of laser 106 and may be manual (for example using a user interface 122), partially automated, or fully automated, depending on design constraints of the system. In particular, controller 120 may receive input from a safety system, for example as described in commonly owned U.S. Patent Nos. 10.634,813 and 10,816,694, U.S. Patent Application Nos. 15,574,659 and 16 / 079,073, InternationalPatent Application No. PCT / US20 / 34104, and U.S. Provisional Application No. 63 / 140,236. The safety system may be designed to turn down or to turn off the beam, for example when an uninterrupted optical path from transmitter 102 to receiver 104 cannot be assured or when other hazardous conditions may be associated with continuing to beam power. Controller 120 may receive input (data) from other components, for example to monitor the health or temperature of the laser. PSU 202 draws power from input power 204. which may be. for example, a power grid, a generator, or a battery, and supplies it to laser 106. In the figure, controller 120 and chiller 114 are directly connected to input power 204, but in other embodiments, these or other components may receive power from power supply unit 202. Chiller 114 monitors the temperature of laser 106 (and / or other components of the transmitter as necessary) and makes sure it does not exceed safe values.

[0034] As shown in Fig. 2, power beam 108 emerges from light source 106 and enters optics unit 110. It will be understood that while tight 108 maintains the same reference numeral throughout Fig. 2, the characteristics of light 108 may change in various ways (e.g., polarization, convergence / divergence angle, beam profile, or intensity) as it passes through different optics and other components. Optics unit 110 may include beam integrator 206 and other optics such as lenses, mirrors, phased arrays, or any other appropriate component for managing direction, divergence, and beam irradiance profile of the light, or for merging different optical power beams and / or signals. Beam integrator 206 will generally be chosen to match the wavelength domain of light source 106, and can be used to change the size, shape, or intensity distribution of the power beam. For example, when beaming power to a receiver, it may be desirable in some implementations to match the beam width to the size of the receiver, and possibly to “flatten” the beam irradiance profile to be relatively uniform across a surface of the receiver, for example converting a substantially Gaussian beam profile to a “top hat” or super-Gaussian profile. Beam direction and beam profile shaping is discussed in more detail in co-pending and commonly owned International Patent Application No. PCT / US20 / 34095. In particular, the mechanisms described therein for monitoring the placement of a power beam on a receiver and using the monitored data to feed back to controller 120 and / or to steering assembly 112 may be incorporated into the present system.

[0035] Steering assembly 112 may include steering optics 210 and / or sensors 212, which may be used in some implementations to provide feedback information for tracking the receiver and pointing the beam at it, to measure the beam characteristics such as direction or irradiance profile, or to monitor for potential intrusions into the light path.Steering assembly 112 may also include merging optics. Merging optics are generally used for combining multiple optical paths, or possibly for separating them when optical flow is in the opposite direction. For example, an outgoing power beam 108 for transmitting power may be combined with an incoming optical beacon 208 used for tracking a receiver, as shown in the figure. As illustrated, the beacon is used at steering assembly 112 for tracking, but in other implementations, signal 208 may propagate to optics unit 110 or beyond.

[0036] Transmitter 102 may also be provided with sensors 214, which may be used to monitor ambient conditions. Sensors 212, 214 may be used to adjust beam integrator 206 and / or steering optics 210. For example, sensors 212 might monitor position of a focusing lens or other optical component in steering assembly 112, while sensors 214 might be used to monitor ambient and / or other component temperatures. Data from sensors 212, 214 may be fed back into controller 120 to adjust laser 106, for example for safety considerations, or to control steering optics 210 and / or steering assembly 112 to direct beam 108 onto the receiver. Control and data signals may pass between controller 120 and other components, as shown by dot-dashed lines in Fig. 2, and controller 120 may control communication with the receiver, for example using transmitter communication unit 124.

[0037] After passing through optics unit 110. power beam 108 is directed bysteering assembly 112 in a desired direction away from transmitter 102. In some implementations, steering assembly 112 may' include steering optics 210, motors for adjusting mirrors or other components (not shown), and / or more shaping optics (not shown). Those of ordinary skill in the art will understand that different implementations may require different arrangements of optical elements (such as the order of components that the light passes through) without changing the fundamental nature of the transmitter system.

[0038] Fig. 3 shows functional relationships betw een components of a power receiver 104, such as the receiver shown in Fig. 1. Illustrated receiver 104 includes power converter 302, which includes PV array 130 of PV cells 132. Po er converter 302 is configured to convert power beam 108 from laser 106 into electricity (or, in some implementations, into another useful form of energy). Receiver 104 may also include optics 304, which may shape or modify the received beam before it reaches PV array 130, for example as described in International Application No. PCT / US20 / 34093. In many implementations, PV array 130 includes a thermal management system 306. This systemmay include passive or active cooling, and it may be configured to send a signal back to transmitter 102 if any part of PV array 130 exceeds safe temperature limits (for example, via RX communication unit 138).

[0039] Power converter 302 may further be connected to power management and distribution (PMAD) sy stem 308. PMAD sy stem 308 may power user devices 310, a power bus 312, and / or energy storage devices 314. PMAD system 308 may be connected to controller 316, which may monitor PV array 130 via sensors 140. for example monitoring voltage, current, and / or temperature of individual photovoltaic cells, groups of cells, or of the whole array, voltage and / or current of the PMAD or of individual loads. Controller 316 may also include Maximum Power Point Tracking (MPPT) for PV array 130. or MPPT may be handled by PMAD system 308. PMAD system 308 may also include DC / DC converters, for example to provide power to devices 310, 312, 314 with preferred voltage and current characteristics. Telemetry unit 318 may send any or all of the above data back to the transmitter for use in controlling light beam 108, for example through RX communications unit 138. In some implementations, controller 316 may communicate with a receiver user interface 320, which may allow local viewing and / or control of receiver operations by a user of the power receiver.

[0040] Also visible in Fig. 3 is a signal 208 (e.g., an optical signal) being sent back to transmitter 102 by receiver 104, which may be sent along the same path as power beam 108 as shown. In some implementations, for example, signal 208 may include a safety signal that is used to assure an uninterrupted path from transmitter 102 to receiver 104. In some implementations, this signal may be sent from safety emitters 136. More details on safety systems may be found, for example, in commonly owned U.S. Patent Nos. 10,580,921, 10,634,813, 10,816,694, and 11.105,954, U.S. Patent Application No. 16 / 079,073, and International Patent Application No. PCT / US20 / 34104. In some implementations, signal 208 may include a tracking signal that is used to position power beam 108 on power converter 302, such as a signal sent from tracking emitters 134. While signal 208 as shown in the figure is an “active” signal, in other implementations, emitters 134, 136 may be replaced by fiducial marks (not shown) that are identified by transmitter 102 or by other appropriate components in the power transmission system.

[0041] Any receiver components that require power, for example but not limited to thermal management system 306, RX communication unit 138, PMAD system 308. controller 316, telemetry unit 318, and / or user interface 320. may be powered by power converter 302 (directly or via PMAD 308) if desired. If components are powered byconverter 302, the system might include a batten- (either as part of energy storage 314 or as a separate component) to power these components during start-up or at other times when converter 302 is not supplying power.Free Space Power Beaming from Orbit

[0042] The International Electrotechnical Commission (IEC) sets standards for lasers to protect people from hazardous exposure to intense light. The standards vary7as a function of wavelength, exposure time, and other safety factors. The continual (greater than 10 second) maximum permissible exposure (MPE) for a point-source 1,070 nm laser light, according to the IEC 60825 standard, is about 5 mW / cm2, a limit that protects the retina from thermal damage. (An exposure of only 1 second would allow up to 9 mW / cm2.) But for distributed sources, the eye can tolerate more light, because of the way the lens of the eye focuses light to a small spot on the retina. With enough angular separation between sources, each source produces a separate spot, so the heat is not cumulative. Fig. 4 is a conceptual diagram of this concept. Eye 400 includes lens 402, which receives light 404, 406 from two separated sources (shown as solid and dashed, respectively) forming an angle a between them. Light rays 404, 406 are focused by lens 402 onto retina 408, each onto a separate point of the retina 408. separated by distance d. As long as each source has an intensity less than the continual point-source MPE and the sources have a minimum angle a between them that is large enough to separate the spots they form on the retina, they remain eye-safe even though the total power transmitted by the sources may exceed the continual MPE.

[0043] Exploiting these properties of the eye and the associated international standards for eye safety, a constellation of relatively small space solar laser power beaming satellites, each capable of delivering a modest amount of pow er (e.g., 1-20 kW or 5-10 kW) of electric power to a small receiver (e g, 15-30 m in diameter) on the ground, can be separated from one another in orbit. As shown below, by virtue of the receiver size, the optical power density can be eye-safe for at least a 1 second exposure, and possibly for more than 10 seconds or even continually. Multiple satellites can send power to a single receiver and still remain eye safe on Earth if they are separated from each other in the sky by more than 1.5 mrad (about 8.6°) because they effectively become an extended source, which increases the MPE. For an orbital altitude of 10,000 km, this translates to about 15 km minimum spacing between satellites. The angle beyond whichthe allowed intensity does not increase any more is 100 mrad (1,000 km from edge to edge of the fleet / array of satellites when at 10.000 km altitude).

[0044] Example applications which might benefit from laser power beaming from space as described herein include:

[0045] Convoy of electric vehicles charging during a break: 120 satellites, each roughly 0.5° (about 8.5 mrad) away from each other (as seen from the ground), each delivering about 15.7 kW of light into a 20-meter beam diameter on the ground, results in about 600 kW electric output. 600kW for 8 hours is 4,800 kWhr, which translates to a full charge for 38 electric vehicles with 125 kWhr batteries (equivalent to a Tesla CyberTruck or Ford F-150 Lightning), or 9+ EVs with 500kWhr batteries (which is in the range of some electric delivery trucks).

[0046] Island community: Per capita average power usage of about 1-1.5 kW. A 30 m beam diameter (larger than the convoy example because it would more likely be a permanent installation, instead of needing to be mobile) could receive about 35 kW of 1,070 nm laser light while remaining below the long-term (>10 sec) exposure limits on average, resulting in more than 11.1 kW of electric output on the ground per 35 kW beam. 50 satellites available (within the 100 mrad viewing angle from the receiver) at any given time to beam power, delivering over 555 kW total (with an average flux of about 250 mW / cm2), could therefore support an independent community of more than 500 people even without any other power sources. (Of course, more than 50 satellites would probably have to be orbited in order to have 50 satellites beaming at any given time, unless satellites were placed in geosynchronous orbit over the island.) By going up to the 1- second exposure limit of 600 mW / cm2, the island could receive 1.3 megawatts of electric power to support a community of nearly 1,200 people. The receiver for a 30 m diameter beam would be about as wide as 12-14 parking spots (and about 3 lanes’ worth of those spots), and could perhaps be part of a roof structure for a parking lot.

[0047] Electrified cargo vessels (in international waters): These vessels can require tens to hundreds of megawatts of power. 100 MW of electric power would require a receiver nearly 270 meters in diameter, which is about the length of a Panamax cargo vessel. (But these vessels are only 32 m wide, except neo-Panamax which may be 51 m wide.) If the power beam is only used when the vessel is a given distance from shore, then allowances might be made to increase the allowed optical power flux (since even if a beam were to miss the receiver, there would not be any humans nearby in the water to beexposed). Increasing it by about 8.5x would enable 100 MW to be delivered to a 50 m diameter receiver.

[0048] Forward operating bases (FOB - military): HVAC can represent a large fraction of the power budget for these installations, depending on climate. Various studies show that HVAC can consume up to 75% of the total electrical power usage of FOBs. See, e.g., Vavris, "‘Power and Energy Considerations at Forward Operating Bases (FOBs).’’ Army Engineer Research & Development Center, June 2010, accessible at apps.dtic.mil / sti / tr / pdf / ADA566876.pdf (accessed September 27, 2025), which is incorporated by reference to the extent not inconsistent herewith. Because FOBs are, by their nature, temporary installations, the cost and effort put into power systems are different than what would be done for permanent installations. Transporting fuel to FOBs to run generators is a large logistical burden, and traditional solar panels plus large battery banks require more land than may be available. See, e.g., Jaffe et al., “Opportunities and Challenges for Space Solar for Remote Installations,” Naval Research Laboratory, Oct. 2019, accessible at nss.org / wp-content / uploads / Space-Solar-for-Remote-Installations- 2019.pdf (accessed September 27, 2025) , which is incorporated by reference to the extent not inconsistent herewith. Similar to the island community example, a power beaming receiver can deliver electric power from a much smaller footprint (for both the light collectors and any batteries).Safety and Exposure Limits for the Human Eve

[0049] The following calculations explore an example system transmitting laser power using 1,070 nm light. This example has been chosen to illustrate the principles involved, but it will be understood that systems may use light of other wavelengths and may include different power levels without departing from the scope of the invention, which is limited only by the claims.

[0050] The equation setting the MPE depends on the wavelength and the subtended angle of the light, and includes multiple empirically determined parameters. The following equation is for a “point” source, defined as any laser source that subtends less than 1.5 mrad of viewing angle:W W W MPEw70nm = 10 C4C7— - = 5 • 10 — - = 0.005 - - > • wsec m nd end point

[0051] The first wavelength factor, C4. is equal to 5 when the wavelength of the light is in the range between 1,050 nm and 1.400 nm. The second wavelength term, C7. is equal to 1 when the wavelength of the light is in the range between 700 nm and 1 ,150 nm.

[0052] For distributed source(s), the MPE can be higher. The MPE increases as the subtended angle of the extended source grows, up to a maximum of 100 mrad (5.7°). This changes the equation, adding in a subtended angle factor C6. For light having a wavelength of 1,050 nm to 1,400 nm, the equation depends on the exposure time. The time T2when 1.5 mrad < a < 100 mrad is defined asT2= 10 • lol 98.5 Jsec

[0053] And T2= 100 sec when a > 100 mrad. When the exposure time t is greater than T2. the equation for MPE is: a W1.5 mrad m2

[0054] When the exposure time t is shorter than T2, it is: a W —1.5 mrad1—

[0055] The factor C6when 1.5 mrad < a < 100 mrad is a6“ a ■

[0056] where aminis 1 .5 mrad (the eye cannot focus extended sources to an angle smaller than 1.5 mrad).

[0057] When using at least the full 100 mrad (5.7°) for the extended source, the MPE can safely range from about 190 mW / cm2(38x the limit for a single point source) for >100 seconds exposure, up to about 850 mW / cm2(170x the point source limit) for 0.25 seconds exposure. For a 1 second exposure limit, assuming that a safety system local to the receiver will be able to detect a person too close or light spilling over the edge of the receiver and shut off lasers within that time period, then the extended source MPE is about 600 mW / cm2(120x the point source limit) when the sources are evenly distributed across the 100 mrad viewing cone. Fig. 5 is a plot showing maximum MPE for three different exposure times for 1,070 nm light. While the examples in this document use the 100 mrad width as a “maximum” width, it is allowed for satellites outside this range to also project an optical power beam at a receiver if the satellite is within the receiver’s acceptance angle.

[0058] A convenient point for measuring the point at which the “vast majority” of encircled power for a perfect Gaussian beam is at the 1 / e4point, which is approximately 2.38x as far out from the center as the point at which 50% of the power is encircled. This point encircles about 98.2% (i.e., 1 - 1 / e4) of the total power. Some of the calculations herein about power output from the receiver make a simplifying assumption that the optical power is evenly distributed across the entire “width” of the beam. In reality, the peak intensity is roughly four times the average intensity.

[0059] Each laser satellite is a separate source, and IEC 60825 adds the requirements for multiple sources that any sub-area must also be within the exposure limits. For example, consider an example of about 120 satellites 602 evenly spaced in a hexagonal grid by just under 0.5° (about 8.5 mrad) within a 100 mrad circle 604, as illustrated in Fig. 6 (not all satellites 602 have been labeled to avoid unnecessarily cluttering the figure). If each one delivers a beam whose intensify is below 5 mW / cm2outside a defined area on the ground, any 20 mrad circle 606 within the larger 100 mrad array could contain at most 7 satellites. The 1 second MPE limit for 20 mrad is 120 mW / cm2, but 7 satellites would only deliver about 35 mW / cm2at the safety border. Similarly for a 60 mrad circle 608, the MPE limit is 360 mW / cm2but fewer than 50 satellites (about 43 in the example shown in Fig. 6) would be within that circle, delivering a total of less than 250 mW / cm2. Other combinations of MPE exposure times and points at which that MPE should not be exceeded are possible.

[0060] Projected beams have some amount of jitter in their location due to electrical, mechanical, thermal, and optical “noise” in the system, including in the tracking and pointing components. The speed of beam jitter depends on the mechanical properties of the transmitter satellite (including satellite bus stability, coarse pointing mechanisms, fast steering mechanisms, and component temperatures), but is likely to have a characteristic frequency greater than 1 Hz, and perhaps greater than 100 Hz. In those cases, in addition to the safety system shut-off (which, as discussed elsewhere, would have a D’ response time less than 1 second), the beam itself would be very unlikely to spend as much as I second at any random jitter offset.

[0061] The transmitter satellites would be designed such that the beam jitter would be a relatively small fraction of the beam width. Therefore, a receiver’s collection aperture diameter should be sized to be larger than the beam width (defined nominally at the 98.2% encircled power level). For example, if the design beam diameter on the ground is 15 meters, and if the expected jitter (at one standard deviation) is ±1 meter, then99.73% of the time the beam center will be within 3 meters from the center of the receiver, and within 5 meters 99.999943% of the time (i.e., it would only be further offset for 1 part in 1,744,278). If the receiver collection aperture diameter is 18 meters, then a portion of the beam would fall outside the optical collection aperture. Structural elements will absorb or diffusively reflect light for some of that area; we’ll assume that adds 1 meter around the edge, such that the total diameter is 20 m. Other beam sizes, collection aperture sizes, and border structure widths are possible.

[0062] Fig. 7 shows example intensity profdes (using the example in the previous paragraph) for different beam displacements, as measured from the center of the receiver. It includes vertical lines showing the nominal beam width (at 7.5 m radius), the beam collection aperture (at 9 m radius), and the edge of the receiver structure (at 10 m from the center). While a perfect Gaussian profile would be non-zero at any point, in reality diffraction effects from finite aperture sizes will make the beam profile subtly different (and effectively zero at some distance from the center). For example, a beam projected through a circular hard aperture will result in an Airy far field beam profile. For purposes of this document, we will stay with the standard practice of using the Gaussian approximation.

[0063] The graph shows the relative intensity of the beam vs. radial distance from the center of the receiver, using the above assumptions: the beam is 15 m diameter (7.5 m radius), the beam collecting aperture is 18 m diameter (9 m radius), and the receiver structure that prevents light from reaching below the structure has a diameter of 20 m (10 m radius).

[0064] One way to determine the power limit for a given (single satellite) beam size would be to take the >10 second exposure limit of 5 mW / cm2and use that as the average beam intensity. This example would estimate about 8.83 kW of light into the receiving aperture, with a peak intensity about 20.4 mW / cm2, and an intensity of 0.37 mW / cm2(or 1.83% of the peak) at the 7.5 meter radius “edge.’' At the 10 m radius (the outer edge of the receiver structure, which we assume is the closest a person would be allowed to get to the beam, both physically and with beam shut-off sensors detecting people near the receiver), the intensity would be 0.02 mW / cm2(0.098% of the peak). If this single beam jitters off center by 3 meters (the three standard deviation distance), then the intensity at the 10 m radius edge would be 0.62 mW / cm2, roughly l / 8ththe >10 second limit. Even at the five standard deviation offset of 5 meters (which would be both rare and brief), the intensity would only be 3.43 mW / cm2(about 16.8% of the peak). As areminder, the 1 second point source exposure limit is 9 mW / cm2, and the greater than 10 second limit is 5 mW / cm2(which is what is used for single satellite beams in the examples discussed herein, but other values could be used for the cut-off limit).

[0065] The above example shows that the per-satellite optical output power limit can be set based on the beam size on the ground, the beam jitter, the size of the keep-out zone, and the beam safety reaction shut-down time, also called the D3time.

[0066] Fig. 8 shows a randomized set of satellite positions (as an example of what the sub-area of a constellation might look like at a given moment) within a 100 mrad window. Fig. 8 includes Fig. 8A and Fig. 8B, with Fig. 8B being a more detailed view of circle 810 within Fig. 8A. Randomized positions are used to approximate a more realistic possible satellite constellation. To show potential variation, note that some areas have higher density of satellites than others. As described above, for compliance with IEC 60825, any circular subset in the diagram must provide less laser radiation than the limit for the size of the circular subset. The 100 mrad circle 804 contains many more than 120 satellites 802, therefore not all of them can be lasing at full power at the same time. Four sub-areas 806, 808. 810, 812 are shown, with widths of 3, 11.5, 20, and 60 mrad respectively. The combined 1 second exposure intensity limits are 18, 69, 120, and 360 mW / cm2corresponding to these circles 806, 808, 810, 812 respectively. There are three satellites just within the 3 mrad circle 806, but if they each deliver 5 mW / cm2at the defined safety radius on the ground, then they are under the 18 mW / cm2limit. Similarly, there are eight satellites inside the shown 1 1.5 mrad circle 808. Their combined 40 mW / cm2intensity is below the 69 mW / cm2limit. There are 13 satellites in the 20 mrad circle 810, and again their combined 65 mW / cm2is below the 120 mW / cm2limit. But as we look at the shown 60 mrad circle 812, there are more than 72 satellites (about 76), and so their combined intensity exceeds the 360 mW / cm2limit. Therefore not all of those satellites can be lasing at their full individually safe power levels.

[0067] The contour plot of Fig. 9 shows the fraction of maximum allowable single-satellite optical output power each satellite is allowed to emit if all of the N satellites (number on the vertical axis) are relatively evenly spaced over the subtended angle a (the horizontal axis). If we were able to space all of the satellites 3 mrad from their nearest neighbors in a square grid, it would be possible to provide as many as 853 satellites within the maximum extended source viewing angle. At the previously calculated 600 mW / cm2intensity limit, that number implies each satellite would be limited to deliver flux even lower than the per-satellite limit of 5 mW / cm2: if each operated at theper-satellite limit, they would deliver a total combined power flux to the receiver of more than 4,265 mW / cm2. In practice, of course, it would often be expected to be more economical to provide fewer satellites delivering more power, as long as the MPE is observed by each satellite and satellite spacing is maintained.

[0068] As another example, imagine if a system were designed such that the maximum allowable optical power output of a single satellite were 20 kW (based on a defined maximum beam power & size on the ground). If there were 200 of these satellites, all evenly distributed within a 50 mrad circle (as seen from the ground), then they could all be lasing on the same target only if each of them limited its output power to about 6 kW (30% of maximum). If the same number of satellites were evenly spread across a 100 mrad circle, then the allowable output power would be 12 kW each (60% of their maximum). Conversely, if it was desirable to operate the satellites at their maximum rated output power, then for the 50 mrad circle only 60 evenly distributed satellites would be allowed to be lasing at the same terrestrial target.

[0069] We use the phrase “multi-scale exposure analysis” to encompass the procedure described above of checking whether the combined satellites in any and all subareas within the larger area (i.e., up to 100 mrad subtended angle) are within the exposure limits for the defined exposure time and position (distance from center) of potential exposure. The phrase “multi-scale exposure curve” is used herein to represent a relationship between sub-area size and allowed exposure limits for that size. A multi-scale exposure curve may be represented as a continuous curve or as a set of points.

[0070] Fig. 10 shows one possible set of logic for determining which satellites will beam to a single receiver. The flow chart begins at Start 1002, and first selects a set of sub-area sizes (step 1004) that will be used for the determination of which sizes of subareas of the acceptance angle of the receiver to use for the multi-scale exposure analysis, which will increment through each size as described below. Enough sub-area sizes should be checked to have confidence that all locations where the exposure defined by the multiscale exposure curve has not been exceeded, while retaining some degree of computational efficiency for the overall algorithm. In some implementations, it may save time to sort the set of sizes from largest to smallest as part of step 1004.

[0071] Once selection step 1004 has occurred, the next step 1006 is to determine the locations of satellites within the acceptance cone of the receiver. This set of locations is used to create a list of “candidate satellites” in step 1008. We then begin a process of iterating through the set of sizes that was chosen in step 1004 as follows.

[0072] We set the sub-area being tested to the first diameter of the defined set of sizes in step 1010. (If the set of sub-area sizes has been sorted from largest to smallest as suggested above, this first sub-area will be the full area of the acceptance angle.) We then locate the sub-area of the selected size that is producing the largest flux on the receiver in step 1012, assuming that all satellites in the “candidate satellite’" list are beaming at full power. There are a variety of possible algorithms for performing this step, most of which involve “scanning” a circle of the selected size over the full test area, but other methods such as searching for local maxima or using a “D8” algorithm for draining water from a digital elevation map may also be used. Once the test area producing the largest flux is identified, we proceed to decision step 1014, which checks to see if the flux on the identified area exceeds the safety threshold for an area of that size (as discussed above in connection with Fig. 8). If it does, we move to step 1016 and choose a satellite to exclude from the set of candidate satellites.

[0073] The satellite to exclude from the set should normally be located within the identified area of maximum flux, and may be chosen to try to maximize the homogeneity of the satellites remaining in the set. For example, it may be useful to use known techniques of spatial descriptive statistics, such as nearest neighbor distance distributions and calculation of Ripley’s K and L functions, in deciding which satellite(s) to remove from the set of candidate satellites. See, e.g.. en.wikipedia.org / wiki / Spatial descriptive statistics (accessed September 30, 2025). Moraga, Spatial Statistics for Data Science: Theory and Practice CRC Data Science Series, 2023 (available at www.paulamoraga.com / book-spatial / the-k-function.html. as accessed September 30, 2025), and Dixon, “Ripley’s K function” Encyclopedia of Environmetrics. vol. 3, pp 1796-1803, 2002 (available at www3.nd. edu / ~mhaenggi / ee87021 / Dixon-K-Function, pdf, as accessed September 30, 2025). Once the satellite to exclude is chosen, that satellite is removed from the list of candidate satellites that was created in step 1008 (step 1016), and we return to step 1012 to check again for the sub-area of the currently selected size that would produce the largest flux on the receiver if all satellites in the candidate satellite list were beaming to the receiver with full power. The algorithm may loop from 1012 to 1014 to 1016 a number of times before finally determining in step 1014 that the flux on the located sub-area of highest flux does not exceed the safety threshold for that area size.

[0074] Once the system has produced a set of candidate satellites that satisfies the flux safety criteria for the size being checked, the algorithm proceeds to step 1018, which checks to see if the full set of sub-area sizes has been checked. If there are more sizes tobe checked, the system proceeds to the next item on the list of diameters in step 1020 and loops back to step 1012. Once all sizes have been checked and the list of candidate satellites has been reduced to a set which passes safety checks at all sizes, in step 1022, the candidate satellites are directed to beam power to the power receiver and the method shown ends at step 1024. Of course, once the algorithm shown in Fig. 10 ends, the satellites (which may have moved) are reassessed again, starting the algorithm again at Start 1002.

[0075] The algorithm shown in Fig. 10 is relatively crude, and many modifications and improvements will occur to those having skill in the art. In particular, using the algorithm of Fig. 10, satellites are either beaming at full power or they are off. A more sophisticated algorithm may also allow for some satellites to beam at less than full power. Those of ordinary skill in the art will understand that other factors may dictate use of a different algorithm, such as one that divides satellites into multiple groups for beaming to different ground-based power receivers. The depicted algorithm is only an example of methods and systems encompassed by the invention, which are limited only by the content of the claims.

[0076] As part of the safety system for the receiver, optical sensors can be placed at one or more radial distances around the receiver. The optical sensors may be filtered to only detect a narrow band around the laser wavelength. Ambient sunlight in that wavelength range is expected to vary relatively slowly (whether due to clouds or to the day / night cycle), therefore the optical sensors will be able to detect rapid changes in the incident beams’ position or size and to respond to rapid changes by signaling for the lasers to be disabled (e.g., if the beam w anders outside the receiver collection area, as discussed above). The round-trip speed of light delay from ground to orbit varies from 3.3 millisec (500 km altitude) to 239 millisec (GEO), therefore the entire safety D3(Detect-Decide- Disable) time can be less than one second.

[0077] Another layer of a safety system may detect humans in the vicinity, rather than detecting the amount of laser light reaching the perimeter of the receiver, and may direct the satellites to turn off (or at least turn down) their lasers to protect humans in areas where they might otherwise sustain injuries.Transmitter Design

[0078] The basic conservation of etendue (and therefore of radiance) sets minimum sizes of transmit and receive apertures for a given source radiance (beam powerand beam quality) and separation distance. The relation is: (TT • BPP • L)2= ^- d^dRJ where BPP (Beam Parameter Product) is a measure of beam quality: L is the separation distance; dTis the diameter of the transmitter optical aperture; and dRis the diameter of the optical beam at the receiver. As an example, to deliver a 1,070 nm beam that is about 15 m in diameter from an altitude of 8,000 km using a laser with a BPP of 0.4 mrmmrad, then the minimum transmitter aperture diameter is at least 85 cm. In practice, it would need to be larger to accommodate beam pointing (which can shift the beam’s position on the optical aperture), clear aperture restrictions, and optical imperfections. If the beam size on the ground was allowed to be larger, then the transmitter aperture could be smaller. Conversely, if the ground receiver needed to be much smaller, for example with a beam diameter of only 2 m, then for the same conditions in the previous example, the theoretical minimum transmitter aperture diameter would be about 6.4 m. Larger transmitter optical apertures are more difficult to fabricate and to launch, making them more expensive than smaller optics.[0079J In this context, pointing “accuracy” refers primarily to beam jitter, that is, how far the beam center moves and shifts away from the desired center. Mathematically, the time-averaged intensity profile of a jittering Gaussian beam profile is broadened to a wider Gaussian (depending on how big the beam jitter is). This time averaging is suitable for understanding how much power will be received by a receiver. For safety concerns, the actual beam position on much shorter time durations (for example, the 1 second limit used in examples throughout this document) is also important to consider. In Fig. 11, the beam (represented by the solid circle 1102 with the solid “X” 1104 at its center) moves around (aka jitters), represented by the three circles with dashed lines and dashed “X” in their centers. The offset of one of those circles is shown as a vector (arrow). Jitter generally occurs in a normal (Gaussian) statistical distribution, and the standard deviation of these movements (when considered over a long enough time) is what we call “accuracy.”

[0080] Beam scintillation due to atmospheric turbulence can be a challenge for laser power beaming in air, at times creating extreme inhomogeneities in the beam intensity' profile. Fig. 12 shows an example calculation of a roughly 15 meter diameter beam propagating all the way down from orbit to the ground, through the entire atmosphere. The beam inhomogeneity is relatively mild, in large part due to the large size of the beam. Therefore the assumptions used herein for beam intensity profile arereasonable. The characteristic time scale of atmospheric scintillation is on the order of 10 Hz to 200 Hz, depending on the amount of turbulence and path length through the atmosphere.

[0081] One of the advantages of this proposed space-based solar power beaming architecture is that each individual transmitter satellite can be small enough to launch as a single payload on existing medium lift rockets, such as the SpaceX Falcon 9. Using the earlier example of satellites each delivering 15.7 kW of light, then after adding in some margin to the design and considering efficiencies throughout the system, the satellite would need approximately 50 kW of input electric power. Adding 20% to enable it to recharge on-board batteries quickly raises it to 60 kW. Current solar cells used in space are approximately 30% efficient, implying the need to collect at least 200 kW of sunlight. That requires 148 m2of active solar cell area exposed orthogonally to sunlight. Expanding the solar array area to 250 m2to allow for gaps between cells, imperfect alignment to the sun, and other inefficiencies would require a panel that would be about 15.9 meters on a side if it were square (or 17.9 meters in diameter if it were a circle).Receiver Design

[0082] The semiconductor materials for more efficient photovoltaic conversion of light into electricity are generally in the III-V family, and are more expensive to use than silicon. They also have higher efficiency for higher incident flux (power intensity) levels, and for the likely wavelengths to be used by the orbital lasers. Therefore, concentrating the incident laser light onto smaller PV areas is desirable.

[0083] The theoretical limit (from conservation of etendue) on the concentration ratio for concentrating light using optics in air is sin2 / sin29. where 9 is the half-angle of light acceptance for the concentrator (light from outside this angle would miss the target, in this case a PV array), and <p is the half-angle of maximum acceptable incidence angle on the target (the maximum would be just under 90°, parallel to the PV surface, i.e., a glancing angle). As one example, for a receiver that could accept light from the maximum extended source full-angle of 100 mrad (5.7°) and allow some margin for pointing, we might choose an acceptance half-angle 9 of 4°. The anti -reflection coatings on PV cells become more complicated as the incidence angle is widened, but it is reasonable to aim for no more than a half-angle < > of 45° from orthogonal onto the cells out of the concentrator. That would result in a maximum concentration ratio of 102.8. For a PV target area of 1 cm2, the concentrating optic could have a maximum diameter of11.4 cm. Efficiently tiling a grid to make a large array would require square or hexagonal optics, inscribed within that diameter for the same acceptance and incidence angles. Such a square would have an area of 64 cm2, and a hexagon would have an area of about84.2 cm2, as shown in Fig. 13. These values all scale linearly with the area of the PV target (which could include multiple PV cells). For example, if the PV array were 10 cm2, then an inscribed square with the above assumptions would be 640 cm2, for a width of25.3 cm.

[0084] Designs for concentrating light are well known in the art. They include reflective, refractive, diffractive, and meta optics, and combinations of those types of optics.

[0085] As described above, the larger that a beam is allowed to be on the ground, the easier it is to design and make the laser transmitting satellites. Making a receiver with a size scale on the order of 10-100 m can be done with modules that include the concentration optics, PV cell(s), enclosure, heat sink, and any connections (for power, data, and maybe cooling). These modules can be designed to easily connect to each other and / or to a larger support structure, enabling the build-up of a large array of the sizes discussed herein.

[0086] There are options for dealing with the constant motion of orbiting satellites. One method is to have satellites start and stop lasing at a specific receiver as they enter and leave the area of its acceptance angle. Another method, which may be particularly useful for smaller constellations that do not provide continual coverage of target points on Earth, is to slew the pointing of the receiver. Depending on the receiver design, this might mean changing the pointing of individual modules, or it could mean changing the pointing the entire receiver array as a single unit. The pointing can be done simply by tilting the receiver to follow a desired '‘center’ point in orbit, or in some designs it could be done by adjusting an element in the receiver: either moving the PV cells to follow a moving focus, or adjusting an optic to keep the focus centered on the PV cells. Techniques for doing these kinds of pointing are well known in the art.Placement of Satellites in Orbit

[0087] Large constellations of satellites, especially those in low Earth orbit, face technical design issues related to scalability, network architecture, interference, and reliability. Much of the work on satellite constellations is focused on communications systems. See, e.g., “Networking for a New Era of Global Satellite Connectivity,” MITLincoln Laboratory, available at www.ll.mit.edu / r-d / proiects / networking-new-era-global- satellite-connectivitv (accessed September 23, 2025), "Capabilities and Limitation of Non- GEO Constellations,” Northern Sky Research, Jan 2022, available at www. analy sy smason, com / contentassets / 86918c46c74348b0b94alba81d2de75c / analvsvs mason capabilities limitations constellations jan2022.pdf (accessed September 23, 2025), and Sheng, et al., "‘Effects of Space Environment on Satellite Mega-Constellations: From Nodes and Links to Network Performance.” Engineering, 2025, available at www. sciencedirect.com / science / article / pii / S2095809925004333 (accessed September 23, 2025), each of which is incorporated herein by reference to the extent not inconsistent herewith. While many of the considerations for communications applications and power applications are similar (and thus the previous work may be used for design of power beaming networks), some may differ. For example, power beaming to Earth from space is expected to be more useful than electrical distribution by more traditional methods (e.g., by copper wires or the like) mostly for remote, temporary, and / or contested locations, where the difficulty7of placing other power distribution systems and the necessary7speed of deployment may make power beaming an attractive alternative. This means that placement of satellite constellations may need to target more remote areas, rather than concentrating on urban regions with high communications needs. Sea lanes may also provide significant locations for deployment of power receivers, exemplifying an area where pow er may be required but traditional power distribution methods may be inadequate (and where safety concerns may be attenuated but not absent, due to reduced population in the receiver area). Another important difference is that communication beams can be much larger than the receiving antennas because they need to maximize signal to noise ratio, whereas power beams should underfill receiving arrays to maximize efficiency and minimize safety issues. Power beaming systems for transmitting power to the Earth may also have substantially more safety' concerns than communications systems because of the intensities required to transmit operationally relevant amounts of pow er; some of these considerations are discussed above in the “Receiver Design” section.

[0088] The orbits of each of the satellites can be chosen to optimize various constellation performance metrics. The 100 mrad (0.1 rad or 5.7°) extended source angle is relative to the view er, and when discussing orbital altitudes w e assume the viewer is at sea level. This means that the relative angles as measured from the center of the Earth are smaller. The viewer being at a higher altitude increases the apparent angle. Those of ordinary skill in the art with understand how to apply this correction. Lower altitudes(e.g. , LEO, at altitudes of up to about 2,000 km from sea level) can reduce the required size of transmit optical apertures, at the cost of faster slew rates and less time on each receiver per satellite. Higher altitudes (e.g., MEO, at altitudes from about 2,000 km to about 35,000 km from sea level, such as altitudes of about 8,000 km to about 10,000 km from sea level) may dramatically reduce slew rate requirements and may provide many hours of time on a single receiver for any satellite, but at the cost of larger transmit apertures. In both cases, the fraction of time that the satellites’ solar arrays can gather energy (and potentially store it) depends on the orbital elements defining the orbit of the satellite, including the fraction of the time that they are in the Earth’s shadow.

[0089] Conversely, the larger the ground receiver can be, the larger each beam can be and therefore more power can be delivered (at the same flux limit) by increasing the beam width, and / or the tracking accuracy requirement can be loosened, since each beam could “wander” further on the receiver without leaving its collection area. Because satellites are in constant motion through their orbits, it would be nearly impossible to actually achieve a uniform spacing between all of the available satellites for beaming power to a given receiver. However, the orbits of all of the satellites in a constellation can be designed to optimize the number of available satellites for selected regions on the ground and their dynamic relative spacing. Optimization of the number and placement of satellites for communications purposes are well-known; those of ordinary skill in the art will understand how to adapt these solutions for purposes of power beaming in light of the instant teachings. There are also algorithms known to those skilled in the art to check these possible combinations of satellites beaming power to a particular location to check if a given configuration would be allowed according to a pre-defined safety exposure threshold.

[0090] High Altitude Platform Stations (HAPS), or other stratospheric platforms such as High Altitude Balloon Stations (HABS), which may operate at about 20,000 to 50,000 km from sea level, can serve as transmitters and / or as receivers of satellite power. HAPS / HABS may either collect (and store) solar energy locally for transmission to the Earth, and / or may source energy from orbital satellites. One advantage of delivering power from orbit to HAPS / HABS is that in the case of a beam missing the HAPS / HABS, it would be expected to be eye safe on the ground, and beams that are intended to overlap at 20 km altitude should not have any overlap on the ground. HAPS / HABS may use energy received from satellites to extend their own flight times, and / or may themselves beam power to ground-based receivers.

[0091] As shown in Fig. 14, some satellites could be within the acceptance angle of more than one receiver (the acceptance cone for each receiver is shown as dash-dotted lines centered on each receiver). In this situation, some of them could project optical power at one receiver, while others could project optical power at another receiver (shown as shaded expanding beams). Depending on many factors (including satellite energy storage level and timing of the satellite receiving solar power; orbital elements; optimization of usage and slewing of each satellite; etc.), satellites may project optical power at a receiver that is not the one closest to it (shown by the apparently crossing beams in the figure).Mobile Receivers for Use with Satellite Constellation

[0092] Some of the use cases for safe laser power beaming from orbit are for temporary' installations, or even for mobile devices (for example, ocean-going cargo vessels). In some of these cases, it is desirable for the receiver to have the ability to be packed / prepared for transportation and then be unpacked / set up for operation quickly and easily. One way to accomplish this objective would be to make some or all of the optical elements inflatable, or achieving their desired shape when put under tension. Some examples can be found at solarthermahvorld.org / news / radicallv -new-design-of-a- concentrating-collector-in-an-inflatable-tube / . www. techbriefs, com / component / content / article / 1833-lew- 16662. and newatlas.com / cool-earth-solar-technology-fossil-fuel-power / 10260 / (each of which was last accessed on September 30, 2025). There are other examples in the art of methods for reducing the time and labor effort required to deploy “large” structures, particularly for modular structures. Some of those methods take inspiration from origami / kirigami.Summary of Claimed Subject Mater

[0093] In the following, further features, characteristics, and advantages are described by items:

[0094] Item 1 : An optical powder beaming system includes a constellation of at least three power beaming satellites and a central controller. Each power beaming satellite includes a laser, a thermal management system for the laser, shaping optics configured to shape a beam from the laser, steering optics configured to direct the shaped beam, the steering optics having an accuracy of within 0.8 prad, a local controller configured to control a power level of the laser, the shaping optics, and the steering optics to direct the steered beam toward a ground-based power receiver, wherein an intensity of the steeredbeam at a first specified distance from the center of the ground-based power receiver is below a predetermined point source optical safety threshold, and a communication system. The central controller is configured to determine which power beaming satellites of the constellation should be beaming power to the ground-based power receiver and to communicate a power level and target location information to the determined power beaming satellites. The combined power intensity from the determined power beaming satellites at a second specified distance from the center of the ground-based power receiver is below a predetermined multi-scale exposure curve. This item provides a technical effect of beaming a large amount of power from orbit while maintaining eye safety on the ground.

[0095] Item 2: A distributed optical power beaming system includes a constellation of at least three power beaming satellites. Each power beaming satellite includes a laser, athermal management system for the laser, shaping optics configured to shape a beam from the laser, steering optics configured to direct the shaped beam, the steering optics having an accuracy of within 0.8 prad, a local controller configured to control a power level of the laser, the shaping optics, and the steering optics to direct the steered beam toward a ground-based power receiver, wherein an intensity of the steered beam at a first specified distance from the center of the ground-based power receiver is below a predetermined point source optical safety threshold, and a communication system configured to communicate with other power beaming satellites of the constellation. The local controller is further configured to determine which other power beaming satellites of the constellation are within a specified acceptance angle of the ground-based power receiver (the “eligible satellites”) and determine whether the total power transmitted from all eligible satellites would exceed a predetermined multi-scale exposure curve at a second specified distance from the center of the ground-based power receiver if all eligible satellites were to beam power at their maximum power levels. If it is determined that the total power transmitted from all eligible satellites at their maximum power levels would not exceed the multi-scale exposure curve, the local controller uses the maximum laser power level. If it is determined that the total power transmitted from all eligible satellites at their maximum power levels would exceed the multi-scale exposure curve, the local controller uses a reduced laser power selected to be produce a total optical power on the ground-based power receiver at the second specified distance from the center of the ground-based power receiver that does not exceed the predetermined multi-scale exposure curve. This item provides a technical effect of beaming a large amount of power fromorbit while maintaining eye safety on the ground, using distributed control of satellite power sources which may not require a central controller.

[0096] Item 3: The distributed optical power beaming system of item 2, wherein a ratio of the reduced laser power to the maximum laser power for each satellite is approximately equal to a ratio of the predetermined multi-scale exposure curve at the second specified distance from the center of the ground-based receiver to the total power at the second specified distance from the center of the ground-based receiver if all eligible satellites were to beam power at their maximum power levels.

[0097] Item 4: The optical power beaming system of any previous item, wherein the intensity of the steered beam at the first specified distance is below the predetermined point source optical safety threshold as averaged over one second.

[0098] Item 5: The optical power beaming system of any previous item, wherein the central controller is configured to determine which second set of power beaming satellites of the constellation should be beaming power to a second ground-based receiver, and to communicate power level and target location information to the second set of power beaming satellites of the constellation.

[0099] Item 6: The optical power beaming system of any previous item, wherein communicating the power level and target location information to the determined power beaming satellites includes communicating the power level and target location information using the communication system of each determined power beaming satellite.

[0100] Item 7: The optical power beaming system of any previous item, wherein the steering optics of each power beaming satellite of the constellation have an accuracy of within 0.3 prad.

[0101] Item 8: The optical power beaming system of any previous item, wherein the laser has a wavelength in the range of about 800 nm to about 1,600 nm.

[0102] Item 9: The optical power beaming system of any previous item, wherein the predetermined multi-scale exposure curve specifies a relationship between viewing area and power level, and the power beaming satellite is configured to beam power only if the relationship between viewing area and power level would be satisfied for all possible viewing areas within the specified acceptance angle of the ground-based power receiver.

[0103] Item 10: The optical power beaming system of any previous item, wherein the constellation includes at least twenty satellites.

[0104] Item 11: The optical power beaming system of any previous item, wherein the constellation includes at least fifty satellites.

[0105] Item 12: The optical power beaming system of any previous item, wherein the constellation includes at least two hundred satellites.

[0106] Item 13: A power beaming system includes a power receiver and a plurality of orbital power transmitters. The power receiver includes a plurality of photovoltaic (PV) cells and has an acceptance angle of at least 100 mrad and a selected spacing angle. Each power transmitter includes a laser, aiming means for the laser having an accuracy of within 0.8 prad. locating means for determining a position of the power transmitter relative to at least one other power transmitter of the plurality, and communication means for communicating with at least one other power transmitter of the plurality, or with a central controller configured to communicate with multiple transmitters of the plurality. In response to a request for power from the power receiver, each power transmitter is configured to determine whether it is positioned within the acceptance angle of the power receiver. If it is within the acceptance angle of the power receiver, it determines whether any other power transmitter of the plurality is close enough to it to appear to be within the spacing angle of the power receiver as viewed by the power receiver, and if no other power transmitter is both within the spacing angle as seen by the power receiver and beaming power to the power receiver, the power transmitter transmits power to the power receiver. This item provides a technical effect of allowing a group of orbital transmitters to manage eye-safe power beaming to a ground-based receiver.

[0107] Item 14: The power beaming system of item 13, wherein the selected spacing angle is at least 3 mrad.

[0108] Item 15: The power beaming system of any of items 13-14, wherein the selected spacing angle is at least 10 mrad.

[0109] Item 16: The power beaming system of any of items 13-15, wherein a power transmitter determining whether any other power transmitter of the plurality is close enough to it to appear to be within the spacing angle of the power receiver as viewed by the power receiver includes communicating with another power transmitter of the plurality to determine whether it is beaming power to the power receiver.

[0110] Item 17: The power beaming system of any of items 13-16, wherein communicating with another pow er transmitter of the plurality’ includes relaying communication through the central controller.

[0111] Item 18: The power beaming system of any of items 13-17, wherein the aiming means has an accuracy of within 0.3 prad.

[0112] Item 19: The power beaming system of any of items 13-18, wherein the plurality of power transmitters includes at least three power transmitters.

[0113] Item 20: The power beaming system of any of items 13-19, wherein the plurality of power transmitters includes at least ten power transmitters.

[0114] Item 21: The power beaming system of any of items 13-20, wherein the plurality of power transmitters includes at least twenty -five power transmitters.

[0115] Item 22: The power beaming system of any of items 13-21, wherein the plurality of power transmitters includes at least fifty power transmitters.

[0116] Item 23: The power beaming system of any of items 13-22, wherein, if a second power transmitter is within the spacing angle, the communication means is configured to communicate with the second power transmitter to determine whether it is transmitting power to the power receiver.

[0117] Item 24: The powder beaming system of any of items 13-23, wherein the communication means include means for transmitting a signal directly to the second power transmitter.

[0118] Item 25: The power beaming system of any of items 13-24, wherein the communication means include means for transmitting a signal to the central controller for further transmission to the second power transmitter.

[0119] Item 26: The power beaming system of any of items 13-25, wherein the central controller is in orbit.

[0120] Item 27: The power beaming system of any of items 13-26, wherein the central controller is ground-based.

[0121] Item 28: The power beaming system of any of items 13-27, wherein the means for determining whether the power transmitter is positioned within the acceptance angle include a GPS system.

[0122] Item 29: The power beaming system of any of items 13-28, wherein the power receiver has an acceptance angle of at least 250 mrad.

[0123] Item 30: The power beaming system of any of items 13-29, wherein the power receiver includes an optical concentrator configured to concentrate received light onto a PV cell.

[0124] Item 31: The pow er beaming system of any of items 13-30, w herein the power receiver further includes a safety system capable of detecting a human in the vicinity of a laser beam and directing the power transmitter to shut off the laser beam within one second of detecting the human.

[0125] Item 32: The power beaming system of any of items 13-31, wherein the safety system is capable of directing the power transmitter to shut off the laser beam within 0.5 seconds of detecting the human.

[0126] Item 33: The power beaming system of any of items 13-32, wherein the power transmitter is further configured to respond to the direction by shutting off the laser beam.

[0127] Item 34: The power beaming system of any of items 13-33, wherein the power receiver further includes a safety system capable of detecting that an amount of transmitted power is missing the receiver and communicating that detection to the power transmitter.

[0128] Item 35: The power beaming system of any of items 13-34, wherein the power transmitter is further configured to respond to the communication of the detection by shutting off the laser beam.

[0129] Item 36: The power beaming system of any of items 13-35, the power transmitter is further configured to respond to the communication of the detection by reducing the power of the laser beam.

[0130] Item 37: A power receiver for receiving laser light having a selected wavelength from orbit, the power receiver including optical concentrating means configured to concentrate the received laser light, the optical concentrating means having an optical aperture and an acceptance angle of at least 100 mrad. a plurality of photovoltaic (PV) cells configured to convert the concentrated laser light to electrical power, wherein the optical concentrating means is configured to direct the concentrated laser light onto at least a subset of the plurality of PV cells, power electronics configured to supply the converted electrical power to a load, and a support structure configured to support the optical concentrating means and the plurality of PV cells, the support structure being further configured to be collapsible for transport and expandable for deployment. This item provides a technical effect of a portable power receiver that can receive laser light from orbit and convert it to power.

[0131] Item 38: The power receiver of item 37, wherein the support structure is further configured to tilt the optical concentrating means to allow the laser light to enter the optical aperture.

[0132] Item 39: The power receiver of any of items 37-38, wherein the power receiver is configured to receive and to convert laser light simultaneously from a plurality of orbital sources.

[0133] Item 40: The power receiver of any of items 37-39, wherein the acceptance angle of the optical concentrating means is at least 250 mrad.

[0134] Item 41: The power receiver of any of items 37-40, further including a safety system configured to detect laser light that misses the optical aperture.

[0135] Item 42: The power receiver of any of items 37-41, wherein the safety system is configured to respond to a detection of laser light that misses the optical aperture by sending a message to an orbital source of the laser light indicating that at least some of the laser light is missing the optical aperture.

[0136] Item 43: The power receiver of any of items 37-42, wherein sending the message to the orbital source includes sending a message to a central controller for retransmission to the orbital source.

[0137] Item 44: The power receiver of any of items 37-43, wherein the support structure is configured to be inflated for deployment.

[0138] Item 45: The power receiver of any of items 37-44, wherein a shape of the optical concentrating means is defined by a shape of the inflated support structure.

[0139] While the foregoing has described what are considered to the best mode and / or other examples, it is understood that various modifications may be made therein, and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications, and variations that fall within the true scope of the present teachings.

[0140] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0141] The scope of protection is limited solely by the claims that now follow. That scope is intended to be as broad as is consistent with the ordinary meanings of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirements of Sections 101, 102, or 103 of the Patent Act, nor should they beinterpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

[0142] Except as stated in the previous paragraph, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, objects, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

[0143] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry' and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity from another without necessarily implying any relationship or order between such entities. The terms “comprise” and “include” in all their grammatical forms are intended to cover a non-exclusive inclusion, so that a process, method, article, apparatus, or composition of matter that comprises or includes a list of elements may also include other elements not expressly listed. An element preceded by “a” or “an” does not, without further constraints, preclude the existence of additional identical or similar elements.

[0144] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features may be grouped together in various examples for the purpose of clarity of explanation. This method of disclosure is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited in each claim. Furthermore, features from one example may be freely included in another, or substituted for one another, without departing from the overall scope and spirit of the instant application.

Claims

What is claimed is:

1. An optical power beaming system, comprising: a constellation of at least three power beaming satellites, each power beaming satellite including: a laser; a thermal management system for the laser; shaping optics configured to shape a beam from the laser; steering optics configured to direct the shaped beam, the steering optics having an accuracy of within 0.8 prad; a local controller configured to control a power level of the laser, the shaping optics, and the steering optics to direct the steered beam toward a ground-based power receiver, wherein an intensity of the steered beam at a first specified distance from the center of the ground-based power receiver is below a predetermined point source optical safety threshold; and a communication system; and a central controller configured to: determine which power beaming satellites of the constellation should be beaming power to the ground-based power receiver; and communicate a power level and target location information to the determined power beaming satellites, wherein the combined power intensity from the determined power beaming satellites at a second specified distance from the center of the ground-based power receiver is below a predetermined multi-scale exposure curve.

2. A distributed optical power beaming system, comprising: a constellation of at least three power beaming satellites, each power beaming satellite including: a laser; a thermal management system for the laser; shaping optics configured to shape a beam from the laser; steering optics configured to direct the shaped beam, the steering optics having an accuracy of within 0.8 prad; a local controller configured to control a power level of the laser, the shaping optics, and the steering optics to direct the steered beam tow ard a ground-based power receiver, wherein an intensity of the steered beam at a first specified distance from the center of the ground-based power receiver is below a predetermined point source optical safety threshold: and a communication system configured to communicate with other power beaming satellites of the constellation, wherein the local controller is further configured to: determine which other power beaming satellites of the constellation are within a specified acceptance angle of the ground-based power receiver (the “eligible satellites”); determine whether the total power transmitted from all eligible satellites would exceed a predetermined multi-scale exposure curve at a second specified distance from the center of the ground-based power receiver if all eligible satellites were to beam power at their maximum power levels; if it is determined that the total power transmitted from all eligible satellites at their maximum power levels would not exceed the multi-scale exposure curve, to direct the local controller to use the maximum laser power level; and if it is determined that the total power transmitted from all eligible satellites at their maximum power levels would exceed the multi-scale exposure curve, to use a reduced laser power selected to be produce a total optical power on the ground-based power receiver at the second specified distance from the center of the ground-based power receiver that does not exceed the predetermined multi-scale exposure curve.

3. The distributed optical power beaming system of claim 2, wherein a ratio of the reduced laser power to the maximum laser power for each satellite is approximately equal to a ratio of the predetermined multi-scale exposure curve at the second specified distance from the center of the ground-based receiver to the total power at the second specified distance from the center of the ground-based receiver if all eligible satellites were to beam power at their maximum power levels.

4. The optical power beaming system of claim 1 or claim 2, wherein the intensity of the steered beam at the first specified distance is below the predetermined point source optical safety threshold as averaged over one second.

5. The optical power beaming system of claim 1, wherein the central controller is configured to determine which second set of power beaming satellites of the constellation should be beaming power to a second ground-based receiver, and to communicate power level and target location information to the second set of power beaming satellites of the constellation.

6. The optical power beaming system of claim 1 or claim 2, wherein communicating the power level and target location information to the determined power beaming satellites includes communicating the power level and target location information using the communication system of each determined power beaming satellite.

7. The optical power beaming system of claim 1 or claim 2. wherein the steering optics of each power beaming satellite of the constellation have an accuracy of within 0.3 prad.

8. The optical power beaming system of claim 1 or claim 2, wherein the laser has a wavelength in the range of about 800 nm to about 1,600 nm.

9. The optical power beaming system of claim 1 or claim 2, wherein: the predetermined multi-scale exposure curve specifies a relationship between viewing area and power level; and the power beaming satellite is configured to beam power only if the relationship between viewing area and power level would be satisfied for all possible viewing areas within the specified acceptance angle of the ground-based power receiver.

10. The optical power beaming system of claim 1 or claim 2, wherein the constellation includes at least twenty satellites.

11. The optical power beaming system of claim 10, wherein the constellation includes at least fifty satellites.

12. The optical power beaming system of claim 10, wherein the constellation includes at least two hundred satellites.

13. A power beaming system, comprising: a power receiver, including a plurality of photovoltaic (PV) cells, the power receiver having an acceptance angle of at least 100 mrad and a selected spacing angle; and a plurality of orbital power transmitters, each power transmitter including: a laser; aiming means for the laser having an accuracy of within 0.8 prad; locating means for determining a position of the power transmitter relative to at least one other power transmitter of the plurality-; and communication means for communicating with at least one other power transmitter of the plurality; or a central controller configured to communicate with multiple transmitters of the plurality, wherein, in response to a request for power from the power receiver, each power transmitter is configured to: determine whether it is positioned within the acceptance angle of the power receiver; if it is within the acceptance angle of the power receiver, determine whether any other power transmitter of the plurality is close enough to it to appear to be within the spacing angle of the power receiver as viewed by the power receiver; and if no other power transmitter is within the spacing angle as seen by the power receiver; and beaming power to the power receiver, transmit power to the power receiver.

14. The power beaming system of claim 13, wherein the selected spacing angle is al least 3 mrad.

15. The power beaming system of claim 13, wherein the selected spacing angle is at least 10 mrad.

16. The power beaming system of claim 13, wherein a power transmitter determining whether any other power transmitter of the plurality is close enough to it to appear to be within the spacing angle of the pow er receiver as viewed by the pow er receiver includes communicating with another pow er transmitter of the plurality to determine whether it is beaming power to the power receiver.

17. The power beaming system of claim 16, wherein communicating with another power transmitter of the plurality includes relaying communication through the central controller.

18. The power beaming system of claim 13, wherein the aiming means has an accuracy of within 0.3 prad.

19. The power beaming system of claim 13, wherein the plurality of power transmitters includes at least three power transmitters.

20. The power beaming system of claim 13, wherein the plurality of power transmitters includes at least ten power transmitters.

21. The power beaming system of claim 13, wherein the plurality of power transmitters includes at least twenty -five power transmitters.

22. The power beaming system of claim 13, wherein the plurality of power transmitters includes at least fifty power transmitters.

23. The power beaming system of claim 13, wherein, if a second power transmitter is within the spacing angle, the communication means is configured to communicate with the second power transmitter to determine whether it is transmitting power to the power receiver.

24. The power beaming system of claim 23, wherein the communication means include means for transmitting a signal directly7to the second power transmitter.

25. The power beaming system of claim 23, wherein the communication means include means for transmitting a signal to the central controller for further transmission to the second power transmitter.

26. The power beaming system of claim 13, wherein the central controller is in orbit.

27. The power beaming system of claim 13, wherein the central controller is ground- based.

28. The power beaming system of claim 13, wherein the means for determining whether the power transmitter is positioned within the acceptance angle include a GPS system.

29. The power beaming system of claim 13, wherein the power receiver has an acceptance angle of at least 250 mrad.

30. The power beaming system of claim 13, wherein the power receiver includes an optical concentrator configured to concentrate received light onto a PV cell.

31. The power beaming system of claim 13, wherein the power receiver further includes a safety system capable of detecting a human in the vicinity of a laser beam and directing the powder transmitter to shut off the laser beam within one second of detecting the human.

32. The power beaming system of claim 31, wherein the safety system is capable of directing the power transmitter to shut off the laser beam w ithin 0.5 seconds of detecting the human.

33. The pow er beaming system of claim 32, wherein the pow er transmitter is further configured to respond to the direction by shutting off the laser beam.

34. The pow er beaming system of claim 13, wherein the pow er receiver further includes a safety system capable of detecting that an amount of transmitted power is missing the receiver and communicating that detection to the power transmitter.

35. The pow er beaming system of claim 34, wherein the power transmitter is further configured to respond to the communication of the detection by shutting off the laser beam.

36. The pow er beaming system of claim 34, wherein the powder transmitter is further configured to respond to the communication of the detection by reducing the power of the laser beam.

37. A power receiver for receiving laser light having a selected wavelength from orbit, the power receiver comprising: optical concentrating means configured to concentrate the received laser light, the optical concentrating means having an optical aperture and an acceptance angle of at least lOO mrad; a plurality of photovoltaic (PV) cells configured to convert the concentrated laser light to electrical powder, wherein the optical concentrating means is configured to direct the concentrated laser light onto at least a subset of the plurality of PV cells; power electronics configured to supply the converted electrical power to a load; anda support structure configured to support the optical concentrating means and the plurality of PV cells, the support structure being further configured to be collapsible for transport and expandable for deployment.

38. The power receiver of claim 37, wherein the support structure is further configured to tilt the optical concentrating means to allow the laser light to enter the optical aperture.

39. The power receiver of claim 37, wherein the power receiver is configured to receive and to convert laser light simultaneously from a plurality' of orbital sources.

40. The power receiver of claim 37, wherein the acceptance angle of the optical concentrating means is at least 250 mrad.

41. The power receiver of claim 37, further comprising a safety' system configured to detect laser light that misses the optical aperture.

42. The power receiver of claim 41, wherein the safety system is configured to respond to a detection of laser light that misses the optical aperture by sending a message to an orbital source of the laser light indicating that at least some of the laser light is missing the optical aperture.

43. The pow er receiver of claim 42, wherein sending the message to the orbital source includes sending a message to a central controller for retransmission to the orbital source.

44. The pow er receiver of claim 37, wherein the support structure is configured to be inflated for deployment.

45. The pow er receiver of claim 44, wherein a shape of the optical concentrating means is defined by a shape of the inflated support structure.

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