WO2025106570A1 - Beam-splitting optics for power beaming - Google Patents

Abstract

An apparatus and method for dividing an incoming power beam among multiple power converters by an arrangement of beam splitters. The incoming power beam may be divided approximately equally between the multiple power converters. A portion of the beam may pass through some or all of the arrangement of beam splitters multiple times en route to the power converters.

Description

BEAM-SPLITTING OPTICS FOR POWER BEAMING

Cross-Reference to Related Applications

This application claims benefit under 35 U.S.C. § 119(e) of United States Provisional Patent Application No. 63/600,573, filed November 17, 2023, which is incorporated herein by reference to the extent not inconsistent herewith.

Background

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 power beam.

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

In one aspect, a method of splitting a power beam includes receiving the power beam at a receiver surface, splitting the received power beam into a first portion and a second portion, directing the first portion toward a first power converter that is configured to convert the first portion into electrical energy, splitting the second portion into a third portion and a fourth portion, directing the third portion toward a second power converter that is configured to convert the third portion into electrical energy, and directing the at least a portion of the fourth portion toward a third power converter that is configured to convert the fourth portion into electrical energy. Splitting the receiver power beam into a first portion and a second portion may include providing a beam splitter in a path of the received power beam, which may be selected from the group consisting of a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam splitter, a waveguide beam splitter, a diffractive beam splitter, a birefringent beam splitter, a mirror including both reflective and transmissive areas, a variable beam splitter, and a partially reflective coating applied to the first power converter or to the second power converter. A ratio of an amount of optical power in the second portion to an amount of optical power in the first portion may be about equal to an integer, which may be equal to a number of power converters in the receiver minus one. Splitting the power beam may include providing a mirror in the path of the received power beam that has a smaller surface area than a transverse beam area of the power beam. The method may further include splitting a remainder of the fourth portion into a fifth portion and a sixth portion, wherein the fifth portion and the sixth portion are directed toward different members of the group consisting of the first power converter, the second power converter, and the third power converter. The method may further include harvesting power from the first, second, and third power converters, for example by serially connecting PV cells of each of the first, second, and third power converters at corresponding positions relative to a profile of the power beam.

In another aspect, an apparatus for splitting a power beam includes an aperture for receiving the power beam, a first power receiver, a first beam splitter, a second power receiver, and a second beam splitter. The first beam splitter splits the power beam received from the aperture into a first portion and a second portion and is arranged to direct the first portion toward the first power receiver. The second beam splitter splits the second portion into a third portion and a fourth portion and is arranged to direct the third portion toward the second power receiver. The apparatus may further include a third power receiver, wherein the second beam splitter may be further arranged to direct the fourth portion toward the third power receiver. The apparatus may further include a third beam splitter, wherein the second beam splitter may be further arranged to direct the fourth portion toward the third beam splitter. The apparatus may further include one or more turning mirrors configured to direct at least a portion of the fourth portion into one or more of the first beam splitter and the second beam splitter. Any of the above-mentioned beam splitters may selected from the group consisting of a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam splitter, a waveguide beam splitter, a diffractive beam splitter, a birefringent beam splitter, a mirror including both reflective and transmissive areas, a variable beam splitter, and a partially reflective coating applied to the first power converter or to the second power converter. The apparatus may be configured to divide the power beam received through the aperture into a plurality of substantially equal portions, wherein each member of the plurality is directed into a different power receiver from the other members of the plurality⁷. Two of the power receivers may each include a plurality of photovoltaic (PV) cells having a geometric arrangement, and each PV cell of the plurality in one of the two power receivers may' be wired in electrical series with a geometrically corresponding PV cell of the other.

In another aspect, a method of splitting a power beam includes receiving the power beam at a receiver surface, splitting the received power beam into a first portion and a second portion, directing the first portion toward a first power converter that is configured to convert the first portion into electrical energy, and directing at least a portion of the second portion toward a second power converter that is configured to convert the directed at least a portion of the second portion into electrical energy. The method may further comprise directing a remainder of the second portion toward a third power converter that is configured to convert the remainder into electrical energy or directing a remainder of the second portion toward the first power converter.

This Summary⁷ 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

The drawing figures depicts one or more implementations in according 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.

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

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

Fig. 3 is an abstracted diagram of the power receiver of Fig. 1. showing interrelationships between components of the receiver. Fig. 4 is a schematic diagram of a beam-splitting system for power harvesting.

Fig. 5 is a schematic diagram of another beam-splitting system for power harvesting, where the components of Fig. 4 have been rearranged into a different aspect ratio.

Fig. 6 is a schematic diagram of yet another beam-splitting system for power harvesting, where the components of Fig. 4 are rearranged into yet another configuration.

Fig. 7 is a schematic diagram showing a '’loopback" configuration, where a receiver uses fewer individual receiver modules than an original design.

Fig. 8 is a schematic diagram showing a configuration where the beam splitters are replaced by partially reflective coatings.

Fig. 9 is a schematic diagram showing a "branched" configuration.

Fig. 10 is a schematic diagram showing a series of annulus-shaped reflectors directing power to different receiver modules.

Fig. 11 is a view of the mirrors of Fig. 10 showing the shapes and sizes of the overlapping mirrors.

Fig. 12 illustrates the difference between beam splitters that preserve the overall shape of a beam profile and those that segment it.

Fig. 13 shows a wiring scheme for maintaining balanced current levels for PV cells in receiver modules.

Detailed Description

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:

U.S. Patent No. 9,800.091 Issued 10/24/2017 Aerial Platform Powered Via an Optical Transmission Element

U.S. Patent No. 10,374,466 Issued 8/6/2019 i Energy Efficient Vehicle with

: Integrated Power Beaming

Each of these related applications and patents is incorporated by reference herein to the extent not inconsistent herewith.

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 pow er transmitter to power a remote sensor, to recharge a battery, or to power an unmanned aenal 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.

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.

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 micro wave 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) may⁷ be substituted without departing from the scope of the application.

Power beaming systems

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 1 10 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 1 16 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.

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 electricity as 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 communication unit 138 is in communication with TX communication unit 124 (as indicated by the dashed line), and may be used for safety', tracking, telemetry, 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.

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) 1 14. 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.

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, International Patent 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 pow er 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.

As shown in Fig. 2, power beam 108 emerges from light source 106 and enters optics unit 110. It will be understood that while light 108 maintains the same reference numeral throughout Fig. 2, the characteristics of light 108 may change in various w ays (e.g., polarization, convergence/divergence angle, beam profde, 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.

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.

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.

After passing through optics unit 110, power beam 108 is directed by steering 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.

Fig. 3 shows functional relationships between 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. Power 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 system may 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).

Power converter 302 may further be connected to power management and distribution (PMAD) system 308. PMAD system 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 cunent 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.

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.

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 by converter 302, the system might include a battery (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.

Daisy Chaining of Receivers

Because the amount of power in beam 108 can be quite large (from hundreds of watts to tens of kW or more), the PV array 130 may be made of multiple PV cells, as illustrated in Fig. 1 and described in more detail in International Patent Application Nos. PCT/US22/13570 and PCT/US23/70783 and in US Patent Application No. 18/262,513. In addition, it may further be convenient to use a modular set of small arrays (which we refer to as “modules” below) to convert fractions of the power beam, as discussed below.

Fig. 4 is a schematic diagram of a system 400 for directing an incoming power beam to several receiver modules. Five receiver modules are shown in the illustrated diagram, but those of ordinary⁷ skill in the art will understand how⁷ this configuration may be adjusted to apply to a system with two, three, four, six, seven, eight, or even more receiver modules. While components may be described below using directional language such as “down” or “left,” it will be understood that these directions are for understanding of the figure, and that the system may be used in any convenient physical orientation.

Incoming power beam 402 is shown entering receiver assembly 400 at an intensity⁷ of 100% (the full beam is captured by the receiver). Beam splitter 406 reflects 1/5 (20%) of the received power and allows the other 4/5 (80%) to pass through the splitter. Beam splitter 406 may be a classic partially silvered mirror, or may be any other suitable type of splitter, such as a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam spliter, a waveguide beam spliter, a diffractive beam spliter, a mirror including both reflective and transmissive areas, a variable beam splitter, and a partially reflective coating applied to one or more power converters. Those of ordinary skill in the art will understand the functional advantages and disadvantages of various types of spliters for different applications, which are also further discussed below. The 1/5 of the beam that is split off at beam spliter 406 proceeds to the right to encounter the receiver module which may include optics 408A. PV cells 410A, electrical components 412A, and thermal components 414A. As discussed above in connection with Fig. 3, optics 408A may further shape or condition the portion of the beam before it enters PV cells 410A. PV cells 410A convert this portion of the beam to electricity', which is transported away by’ electrical connections 412A. Some of these components may include other components, such as but not limited to sensors (e.g., to measure electrical output) or voltage regulators (e.g., a voltage boost board), and some implementations may not include all of the illustrated elements. To avoid clutering the figure, optics, PV cells, electrical components, and thermal components to the right of beam spliters 416 and 418 are not labeled, but those components may be present. Methods of interconnecting electrical connections 412A, 412D, 412E, and any other electrical components of the receiver for extracting power are further discussed in U.S. Patent Application No. 18/262,513 and PCT Application No. PCT/US23/70783. Thermal components 414A act to remove waste heat from PV cells 410A and electrical connections 412A. In some embodiments, thermal components 414A may include a dedicated heat sink just for one receiver module, while in other embodiments, the thermal components may work together to remove heat from multiples receiver modules, for example by means of heat pipes or a fluid circulation system.

The 4/5 of power beam 402 that is not reflected by beam spliter 406 continues in a downward direction to beam spliter 416, which splits 1/4 of the remaining beam (which represents 20% of the original beam 402) to the right to enter the associated optics, while the remaining 3/4 (60% of the original beam 402) continues downward. Beam spliter 418 splits 1/3 of the remaining beam (another 20% of the original beam 402) to the right to enter the associated optics, and the other 2/3 continues downward. Finally, beam spliter 420 splits 1/2 of the remaining beam (another 20% of original beam 402) tow ards optics 408D. The last 20% of beam 402 then passes through optics 408E, to reach PV cells 410E, which are served by electrical connections 412E to remove electricity and thermal components 414E to remove heat. In this illustration, each receiver module is designed to receive a substantially equal amount of power, and beam splitters 406, 416, 418, 420 are designed to reflect 1/5, 1/4, 1/3 and 1/2 of the beam toward their respective receiver modules. (In general, for a system with N modules, splitters reflecting 1/N, 1/(N- 1 ), ... 1/2 will result in substantially equal amounts of power being directed to each module.) Those of ordinary skill in the art will understand that in some implementations, it will be preferable not to direct the same amount of power to each module, and that this can be accomplished by adjusting the amount reflected by each beam splitter.

It will be understood that each of receiver modules described above is substantially identical except for the fraction of light reflected by the beam splitters 406, 416, 418, 420, and further that the last set of components 408E, 410E, 412E, and 414E are also identical to these modules except for lacking a beam splitter. For manufacturing convenience, each set of components 408, 410, 412, 414 could be manufactured as an identical receiver module, to be attached to a single splitter unit including components 406, 416, 418, 420. It will be understood that in some embodiments, receiver modules may differ in other ways.

Fig. 5 shows substantially the same receiver modules as Fig. 4, rearranged into a configuration with a lower aspect ratio. Each module 404X includes the components labeled 408X, 410X, 412X, and 414X in the previous figure for ease of reference. The beam splitters differ slightly from the ones of Fig. 4; beam splitter 506 reflects 4/5 of the light energy to the left and allows 1/5 to pass through. Beam splitter 516 allows 1/4 to pass straight through and reflects 3/4 down; beam splitter 518 allows 1/3 to pass straight through and reflects 2/3 to the left, and beam splitter 520 allows 1/2 to pass straight through and reflects 1/2 down. Thus, each splitting ratio becomes the fraction transmitted instead of the fraction reflected in this implementation (because in this implementation, unlike the one shown in Fig. 4, the '‘straight” path leads to the receiver module, and the redirected path leads to the next beam splitter or to the final receiver module). Each module 404X performs the same function as in Fig. 4 and is internally arranged in substantially the same way; they merely have been placed in a different configuration, which changes the overall aspect ratio of the system. The thermal components are farther apart in this configuration, possibly making it less convenient (but still feasible) for them to share a cooling system, but the arrangement is more compact and may be easier to fit into a small space, and it may spread out the heat, which may be convenient if each module radiates its heat directly. The modular system makes it easy to create different geometries using mostly the same components. Fig. 6 is another schematic diagram expanding the concept of rearranging the modules of Fig. 4 (and Fig. 5) into a third dimension in a summary fashion. Details of individual components have been omitted, but will generally be substantially similar to those shown in the preceding figures. Beam splitters are shown as light-colored boxes, and power receiver modules are shown as dark boxes. Expanding into this type of three- dimensional arrangement may increase flexibility' in design to accommodate various size and shape restrictions in packaging, electrical or thermal interfaces, or the like.

Fig. 7 shows another configuration illustrating the abi 1 i ty to put a ‘loopback” reflector at the end of a chain of receivers to send power back towards the transmitter, and to use slightly different integer-fractional beam splitters to pick off more power on the way back. This may enable the number of receiver modules to be changed after installation. In the depicted example, a system that had been designed and installed for 5 receiver modules (as shown in Fig. 4) has been cut down to 3 receiver modules (positions of the receiver modules 404 have been separated to accommodate more detail in the figure). The light is first split by 1/5 at beam splitter 602 (analogous to beam splitter 406 in Fig. 4). then by 1/4 at beam splitter 604 (analogous to beam splitter 416). then by 1/3 at beam splitter 606 (analogous to beam splitter 418), sending 20% of light beam to each receiver module 404. The light is then reflected back upwards by 100% reflective turning mirrors 608, 610. As it goes back up towards the transmitter, it reaches beam splitter 612 which splits it by 1/3. beam splitter 614 which splits it by 1/2, and a final turning mirror 616. Beam splitters 612, 614 and turning mirror 616 each effectively add another 2/15 of the power to each of receiver modules 404, summing to a net 33.33% to each of the now-3 receiver modules 404. Each of beam splitters 602, 604, 606. 612, 614 is assumed to pass/reflect the same amount of light regardless of direction of the beam. Note that Fig. 7 does not graphically indicate light that goes through multiple loops, but calculations (assuming the plain turning mirrors 608, 610, 616 are 100% reflective) show that each of the three receivers does, indeed, receive equal amounts of power (33.3% of the originally incident power), as shown in Table 2 below.

Table 2

Table 2 shows the amounts of three cycles of light going around the loopback module into different components, as shown in Fig. 7. Column 1 shows the position that light is coming from, column 2 shows the beam splitter and whether the light is passed through or reflected, column 3 shows the percentage of light split into each direction, column 4 shows the location the light is directed to (as marked on Fig. 7), column 5 shows the percentage of the original light beam sent to that direction, and column 6 shows the amount of power delivered to each receiver during the cycle (which is equal for all three receivers in this example, so only one column is shown). In cycles 2 and 3. there are multiple entries for beam splitters B and C, because light enters those splitters from two directions (from A and from E for beam splitter B, and from B and from D for beam splitter C). For a given splitter ratio (in this example, 80% pass-through for splitter A), 80% of the light that arrives from the left will proceed to the right (while 20% will be reflected down), while 80% of the light that arrives from the top will proceed to the bottom (while 20% will be reflected to the right), so two lines are needed to correctly account for all light entering and leaving the beam splitter. Since only three cycles appear in Table 2, receivers RX1, RX2, and RX3 each are shown to receive 32.8% of the light shown (20% + 10.67% + 2. 13%), and the remaining 1.6% of the light is still circulating, but as the cycles continue, all of the light is eventually accounted for and each receiver receives 33.33% of the total amount. If different reflectivity percentages are chosen, then the receiver modules will not necessarily each receive the same amount of light, but the same techniques can be used to predict how much optical power each receiver module will receive. If the mirrors do not have the same splitting properties for light coming from the left-hand side of Fig. 7 as for light coming from the top of the figure, that also can be accommodated by changing the reflectivity percentages listed above.

Another novel implementation of the same beam-splitting concept is shown in Fig. 8. In this arrangement, the beam splitters shown in Fig. 4-Fig. 7 are replaced by reflective coatings directly attached to the receiver modules. Receiver module 702 has partially reflective coating 704, which reflects 4/5 of light received toward receiver module 706 and allows 1/5 of the light to reach receiver module 702. Receiver module 706 has partially reflective coating 708, which reflects 3/4 of light received tow ard receiver module 710 and allows 1/4 of light received (which is 1/5 of the original total) to reach receiver module 706. Similarly, receiver module 710 has partially reflective coating 712 that reflects 2/3 of light received toward receiver module 714, and receiver module 714 has partially reflective coating 716 that reflects 1/2 of light received toward final receiver module 718, which has no reflective coating and accepts substantially all light received. In alternate embodiments (not shown), the same type of splitter may include loopback turning mirrors (with substantially 100% reflectivity) to reflect any stray light reflected from receiver module 718, either back to receiver module 718 or around to reenter receiver module 702 or receiver module 706. In these alternate embodiments, reflectivities of the partially reflective coatings may need to be adjusted if it is desired to direct equal amounts of optical power to each of the receiver modules. Of note is that the coatings and optics of the receiver modules in the embodiment shown in Fig. 8 must be able to accommodate an entrance angle of about 45°.

By the nature of beam splitting, multiple branches of receivers can also be formed. Fig. 9 shows one example. In this example, light is first split by a 50%/50% splitter 902, but instead of sending some of that light into a receiver module, the two beams are separately directed to a chain of splitters + receivers (in the illustrated case, '‘simple” chains like those shown in Fig. 4). This example also show s that the two separate branches do not need to be equal to each other in the number of receiver modules in the chain. The bottom branch is substantially similar to Fig. 4, and evenly divides its input power into fifths that reach five receiver modules 904. Because its input is only half of the overall input, each of the five receiver modules 804 gets 10% of the original beam 402. The topright branch, however, only has four receiver modules 806, so its input power is split into quarters. The four receiver modules 806 each get 12.5% of the original input power of beam 402. This kind of structure might be used if the 3D geometry constraints on the overall structure could be better solved with a multi-branch solution, or if one branch represents a partial system upgrade with more efficient receivers, enabling the use of four modules instead of five to get the same output power, or if two power outputs require different amounts of power.

In another embodiment, especially if the incident beam has a substantially flat -top beam intensity profile, then the “beam splitters” can instead be implemented as fully reflective mirrors that are smaller than the full beam size and cover a fraction of the total beam area equal to the fraction of the total power to be redirected. If the beam is not substantially flat-top, this type of implementation can still be used as long as the expected beam profile is known, so that substantially similar (or at least predictable) amounts of power can be directed to each PV module. Those of ordinary skill in the art will understand how to integrate the expected irradiance of a non-flat-top beam in order to direct similar amounts of optical pow er to each PV module.

Fig. 10 show s an example implementation using a square, collimated, flat-top beam and a set of rectangular, annular mirrors, which are also shown in Fig. 11. While the annular mirrors have a rectangular shape when viewed from direction A as shown in Fig. 10, the mirrors and the holes within them have a substantially square shape when viewed from direction B. For simplicity, the mirrors described below⁷ are presumed to be infinitely thin and exactly the same w idth as the flat-top beam, but of course in a real implementation, mirror shapes may be adjusted to account for beam divergence, imperfect collimation, or other “real-world” factors. Incoming light 402 reaches first mirror 1002, which reflects 1/5 of it 1004 toward receiver module 1006 (the width of the hole in the mirror is 89.4% of the width of the full mirror for this simple case). As illustrated, reflected light 1004 will form a square annulus (a “picture frame” shape). If desired, additional optics can be used at the entrance to the PV module to flatten the intensity profile or otherwise change the profile for optimal use by the PV cells in the module. Light which is not reflected by mirror 1002 continues on, where 1/4 of it is reflected by mirror 1008 (which has a hole that is 77.5% of the width of the full mirror) toward receiver module 1010, and so forth through mirrors 1012 (63.2% width hole) and 1014 (44.7% width hole) in substantially the same manner described above in connection with Fig. 4. Fig. 11 shows mirrors 1002, 1008, 1012, 1014 as view ed from direction A in Fig. 10. In other implementations, mirrors may be round, elliptical, or of any other appropriate shape, and as discussed above, the size and placement of the holes may be adjusted to account for a non-uniform beam profile. The type of beam splitting shown in Fig. 10 can be contrasted with that shown in Fig. 4-Fig. 9 in that the beam profile in Fig. 10 is geometrically segmented, while the beam profile in Fig. 4-Fig. 9 has its shape preserved. This difference is illustrated in Fig. 12, which show s a contour plot of a beam profile, and shows two ways of splitting the beam. At left is a pure “profile segmenting” embodiment, where each quadrant of the beam is directed to a different PV module, and at right is a pure “profile preserving” embodiment, where the shape of the beam profile is perfectly preserved as it is sent to each PV module. Of course, most real-world beam splitters will not exactly match either of these two ideals, but a substantially profile preserving splitter that splits the beam into equal parts of reduced intensity may allow the use of novel PV array wiring schemes, as discussed in the next section. Copending and commonly owned patent application no. 17/613,015, entitled “Remote Power Beam-Splitting” and filed November 17, 2023, also splits beams and redirects them to individual PV cells, but does so in a profile segmenting manner, rather than the profile preserving manner discussed below' in connection with the section “Wiring for Use with Daisy Chained Receivers.”

In general, beam splitters can be broadly categorized as either polarizing or nonpolarizing. While most beam splitters have a degree of polarization sensitivity as a function of incidence angle, polarizing beam splitters are specifically designed to split light into its constituent orthogonal polarizations through the use of birefringent materials (e.g, a Wollaston prism) or through polarization-dependent surface reflectivities (e.g, a wire-grid polarizer or a MacNeill mirror). Polarization-dependent surface reflectivity can be enhanced through the use of multilayered optical thin films (MacNeill), or by aligning a patterned reflective film to a particular polarization axis (w ire grid). Patterned surfaces can also be engineered to split or reshape the beam through diffraction.

When the number or power capacity of different receiver modules is not known in advance (or changes), it may be desirable to use a tunable beam splitter, which can be realized by adjusting the reflectivity of mirror surface(s). Both polarizing and nonpolarizing beam splitters can be made tunable through mechanical, thermal, or electrical adjustment of the effective film thickness, film reflectivity, or surface pattern. In a dielectric mirror consisting of one or more thin dielectric films deposited on a substrate (e.g. , a Bragg mirror), tuning can be done through heating the films, which changes their optical thickness and reflectivity at a particular w avelength. For semiconductor films, in addition to the thermo-optic effect, the optical thickness can often be tuned through electric carrier injection or by applying an electric field. Electro-optic tuning (e.g, Kerr effect, Pockels effect) is the primary' mechanism for tuning bulk crystals or thin films of electro-optic materials such as LiTaOs and LiNbOs, though they can be thermally tuned as well. Birefringence is often induced with the electro-optic effect, which can either enhance or diminish the polarization sensitivity' of the tuning. In another implementation, an etalon, consisting of an air cavity' and two partially reflecting mirrors, can be tuned mechanically by adjusting the distance between the mirrors.

As alternative to changing the reflective properties of the reflective surface, a tunable beam splitter can also be realized by combining a polarizing beam splitter with an adjustable input polarization. The polarizing beam splitter can be formed from a grid of metal wires (e.g., wire grid polarizer), a stack of dielectric films (e.g., MacNeill mirror), or through the divergence of beams aligned to the fast and slow axes of a birefringent prism (e.g., Wollaston prism). The input polarization can then be adjusted mechanically through rotation of a waveplate, or electrically through electric field-induced birefringence to change the overall retardance (e.g, Kerr cell, Pockels cell, liquid cry stal).

Wiring for Use with Daisy Chained Receivers

The previous section has described various ways that an incoming light beam maybe divided so that portions of the beam may be directed to different receivers. For embodiments like those shown in Fig. 4-Fig. 9 where the beam profile is substantially preserved at each receiver array, this feature can also be used to improve array efficiency.

As discussed extensively in copending and commonly owned U.S. Patent Application No. 18/262,513, filed July 21, 2023, and titled ‘Tower Receiver Electronics/’ PV cells may often be wired in series in order to build up to reasonable voltage levels, especially' when cells having only one or two junctions are used. This practice is often beneficial for solar cells, because the intensity' of sunlight generally does not vary' substantially on the scale of a solar panel. In contrast, laser illumination for power beaming frequently involves significant variation of beam profile intensity’ on a distance scale comparable to the size of individual PV cells. Wiring PV cells in simple series for this application may hinder array efficiency, because (barring the use of bypass diodes or similar solutions) series-w ired cells are usually limited to approximately the current of the least-illuminated cell in a series group. The ’513 application mentioned above uses a physically dispersed parallel wiring scheme to alleviate this issue. For some embodiments of the daisy -chained receivers described in the previous section, a different scheme may be used. As shown in Fig. 12 (at the arrow labeled “profile preserving”), the receiver embodiments discussed in connection with Fig. 4-Fig. 9 split a power beam into several parts, which each maintain approximately the beam profile (at least for collimated beams). If the beam splitters are designed to create approximately equal total illumination on each array, then the arrays can be wired in series so that each series string consists of cells that correspond to the same portion of the beam profile and thus are expected to produce similar currents. This arrangement is illustrated in Fig. 13.

In Fig. 13, beam profile 402 is split across four PV arrays 410A-D, preferably with about 25% of the total beam irradiance going to each of the four arrays as discussed above. Each PV array 410A-D includes 16 PV cells arranged in a 4x4 pattern. When wiring these arrays to harvest their power, corresponding cells in each of the four arrays 410A-D are wired in series - for example, the four individual cells 1302A-D are wired in series to one another, adding together their voltages for the output. (These cells have been displaced somewhat from their actual physical positions in the drawing for ease of illustration of their wiring.) Since each of these cells should be seeing approximately the same level of illumination from the same portion of the beam, little power is lost to current mismatch. While the beam profile may vary along the length of a power beam, the amount of variation is expected to be small on the scale of the positioning of arrays 410A-D for a collimated beam. Thus, the illustrated embodiment would have sixteen series-wired strings of four cells each, where each group of four cells receives approximately the same amount of optical power. These sixteen strings may themselves all be wired in parallel, be wired into parallel groups as discussed in the ’513 application, or they may be individually used for power harvesting (with voltage boosting if desired). While the illustrated embodiment uses sixteen strings of four cells each, it will of course be understood that other embodiments may use different numbers and/or arrangements of PV cells.

In the following, further features, characteristics, and advantages are described byitems:

Item 1 : A method of splitting a power beam including receiving the pow er beam at a receiver surface, splitting the received powder beam into a first portion and a second portion, directing the first portion tow ard a first power converter that is configured to convert the first portion into electrical energy, splitting the second portion into a third portion and a fourth portion, directing the third portion toward a second power converter that is configured to convert the third portion into electrical energy, and directing the at least a portion of the fourth portion toward a third power converter that is configured to convert the fourth portion into electrical energy. This method may have the advantage of allowing the received power beam to be efficiently directed to a variety of different power converters in the system.

Item 2: The method of item 1, wherein splitting the receiver power beam into a first portion and a second portion includes providing a beam splitter in a path of the received power beam.

Item 3: The method of item 1 or 2, wherein the ratio of an amount of optical power in the second portion to an amount of optical power in the first portion is about equal to an integer.

Item 4: The method of any of items 1-3, wherein the integer is equal to a number of power converters in the receiver minus one.

Item 5: The method of any of items 1-4, wherein the beam splitter is selected from the group consisting of a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam splitter, a waveguide beam splitter, a diffractive beam splitter, a birefringent beam splitter, a mirror including both reflective and transmissive areas, a variable beam splitter, and a partially reflective coating applied to the first power converter or to the second power converter.

Item 6: The method of any of items 1-5, wherein splitting the power beam includes providing a minor in the path of the received power beam that has a smaller surface area than a transverse beam area of the power beam.

Item 7 : The method of any of items 1 -6, further including splitting a remainder of the fourth portion into a fifth portion and a sixth portion, wherein the fifth portion and the sixth portion are directed toward different members of the group consisting of the first power converter, the second power converter, and the third power converter.

Item 8: The method of any of items 1-7, further including harvesting power from the first, second, and third power converters.

Item 9: The method of item 8, wherein the first, second, and third power converters each include a plurality of photovoltaic (PV) cells, and one PV cell from each of the first, second, and third power converters at corresponding positions relative to a profile of the power beam are wired in series.

Item 10: An apparatus for splitting a power beam, including an aperture for receiving the power beam, a first power receiver, a first beam splitter for splitting the power beam received from the aperture into a first portion and a second portion, wherein the first beam splitter is arranged to direct the first portion toward the first power receiver, a second power receiver, and a second beam splitter for splitting the second portion into a third portion and a fourth portion, wherein the second beam splitter is arranged to direct the third portion toward the second power receiver. This apparatus may have the advantage of allowing the received power beam to be efficiently directed to a variety⁷ of different power converters in the system.

Item 11: The apparatus of item 10, further including a third power receiver, wherein the second beam splitter is further arranged to direct the fourth portion toward the third power receiver.

Item 12: The apparatus of item 10 or 11, further including a third beam splitter, wherein the second beam splitter is further arranged to direct the fourth portion toward the third beam splitter.

Item 13: The apparatus of any of items 10-12, further including one or more turning mirrors configured to direct at least a portion of the fourth portion into one or more of the first beam splitter and the second beam splitter.

Item 14: The apparatus of any of items 10-13, wherein the first beam splitter and the second beam splitter are each selected from the group consisting of a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam splitter, a waveguide beam splitter, a diffractive beam splitter, a birefringent beam splitter, a mirror including both reflective and transmissive areas, a variable beam splitter, and a partially reflective coating applied to the first power converter or to the second power converter.

Item 15: The apparatus of any of items 10-14, wherein the apparatus is configured to divide the power beam received through the aperture into a plurality⁷ of substantially equal portions, wherein each member of the plurality⁷ is directed into a different power receiver from the other members of the plurality.

Item 16: The apparatus of item 15, wherein two of the power receivers include a plurality of photovoltaic (PV) cells having a geometric arrangement, and each PV cell of the plurality in one of the two power receivers is connected in electrical series with a geometrically corresponding PV cell of the other of the two pow er receivers.

Item 17: A method of splitting a pow er beam, including receiving the power beam at a receiver surface, splitting the received power beam into a first portion and a second portion, directing the first portion toward a first power converter that is configured to convert the first portion into electrical energy⁷, and directing at least a portion of the second portion toward a second power converter that is configured to convert the directed at least a portion of the second portion into electrical energy. This method may have the advantage of allowing the received power beam to be efficiently directed to a variety of different power converters in the system.

Item 18: The method of item 17, further including directing a remainder of the second portion toward a third power converter that is configured to convert the remainder into electrical energy.

Item 19: The method of item 17 or 18, further including directing a remainder of the second portion toward the first power converter.

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.

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.

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 be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

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. 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.

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 vanous 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. A method of splitting a power beam, comprising: receiving the power beam at a receiver surface; splitting the received power beam into a first portion and a second portion; directing the first portion toward a first power converter that is configured to convert the first portion into electrical energy; splitting the second portion into a third portion and a fourth portion; directing the third portion toward a second power converter that is configured to convert the third portion into electrical energy; and directing the at least a portion of the fourth portion toward a third power converter that is configured to convert the fourth portion into electrical energy.

2. The method of claim 1, wherein splitting the received power beam into a first portion and a second portion includes providing a beam splitter in a path of the received power beam.

3. The method of claim 2, wherein the ratio of an amount of optical power in the second portion to an amount of optical power in the first portion is about equal to an integer.

4. The method of claim 3, wherein the integer is equal to a number of power converters in the receiver minus one.

5. The method of claim 2, wherein the beam splitter is selected from the group consisting of a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam splitter, a waveguide beam splitter, a diffractive beam splitter, a birefringent beam splitter, a mirror including both reflective and transmissive areas, a variable beam splitter, and a partially reflective coating applied to the first power converter or to the second power converter.

6. The method of claim 1 , wherein splitting the power beam includes providing a mirror in the path of the received power beam that has a smaller surface area than a transverse beam area of the power beam.

7. The method of claim 1, further comprising splitting a remainder of the fourth portion into a fifth portion and a sixth portion, wherein the fifth portion and the sixth portion are directed toward different members of the group consisting of the first power converter, the second power converter, and the third power converter.

8. The method of claim 1, further comprising harv esting power from the first, second, and third power converters.

9. The method of claim 8, wherein: the first, second, and third power converters each include a plurality of photovoltaic (PV) cells; and one PV cell from each of the first, second, and third power converters at corresponding positions relative to a profile of the power beam are wired in series.

10. An apparatus for splitting a power beam, comprising: an aperture for receiving the power beam; a first pow er receiver; a first beam splitter for splitting the powder beam received from the aperture into a first portion and a second portion, wherein the first beam splitter is arranged to direct the first portion toward the first power receiver; a second power receiver; and a second beam splitter for splitting the second portion into a third portion and a fourth portion, w herein the second beam splitter is arranged to direct the third portion toward the second power receiver.

11. The apparatus of claim 10, further comprising a third power receiver, wherein the second beam splitter is further arranged to direct the fourth portion toward the third power receiver.

12. The apparatus of claim 10, further comprising a third beam splitter, wherein the second beam splitter is further arranged to direct the fourth portion toward the third beam splitter.

13. The apparatus of claim 10, further comprising one or more turning mirrors configured to direct at least a portion of the fourth portion into one or more of the first beam splitter and the second beam splitter.

14. The apparatus of claim 10, wherein the first beam splitter and the second beam splitter are each selected from the group consisting of a dielectric coated mirror, a semiconductor coated mirror, a metal coated mirror, a pellicle, a MEMS beam splitter, a waveguide beam splitter, a diffractive beam splitter, a birefringent beam splitter, a mirror including both reflective and transmissive areas, a variable beam spliter, and a partially reflective coating applied to the first power converter or to the second power converter.

15. The apparatus of claim 10, wherein the apparatus is configured to divide the power beam received through the aperture into a plurality of substantially equal portions, wherein each member of the plurality is directed into a different power receiver from the other members of the plurality⁷.

16. The apparatus of claim 1 , wherein: two of the power receivers include a plurality of photovoltaic (PV) cells having a geometric arrangement; and each PV cell of the plurality in one of the two power receivers is connected in electrical series with a geometrically corresponding PV cell of the other of the two power receivers.

17. A method of spliting a power beam, comprising: receiving the power beam at a receiver surface; spliting the received power beam into a first portion and a second portion; directing the first portion toward a first power converter that is configured to convert the first portion into electrical energy; and directing at least a portion of the second portion toward a second power converter that is configured to convert the directed at least a portion of the second portion into electrical energy.

18. The method of claim 17, further comprising directing a remainder of the second portion toward a third power converter that is configured to convert the remainder into electrical energy.

19. The method of claim 17, further comprising directing a remainder of the second portion toward the first power converter.