Abstract: Systems, methods, and apparatus by which solar energy may be collected to provide heat, electricity, or a combination of heat and electricity are disclosed herein.

Abstract: Method of maintaining or widening the long-term operating temperature range of a heat transfer medium and/or heat storage medium comprising a nitrate salt composition selected from the group consisting of alkali metal nitrate and alkaline earth metal nitrate and optionally alkali metal nitrite and alkaline earth metal nitrite, wherein all or part of the nitrate salt composition is brought into contact with an additive composed of a combination of elemental oxygen and nitrogen oxides.

Abstract: Method of maintaining or widening the long-term operating temperature range of a heat transfer medium and/or heat storage medium comprising a nitrite salt composition comprising, as significant constituents, an alkali metal nitrate or an alkaline earth metal nitrate or a mixture of alkali metal nitrate and alkaline earth metal nitrate and in each case an alkali metal nitrite and/or alkaline earth metal nitrite, wherein all or part of the nitrite salt composition is brought into contact with an additive composed of nitrogen and/or noble gases, in each case with elemental oxygen, the latter in an amount in the range from 0 to 20% by volume based on the total amount of the additive in combination with nitrogen oxides and/or compounds which generate nitrogen oxide.

Abstract: The present invention is a solar panel that generates electricity and extracts heat. A set of such panels may be assembled into a blind. The blind may have a frame that can be retrofit on an existing window. Fluid in the panel is heated by incoming solar radiation, causing it to move, constrained by a one-way valve, in one direction. A Tesla Valve may be used as the one-way valve. The moving fluid may pass through a generator, generating electricity. Heat may be extracted from the fluid by a heat exchanger. The heat may be used to heat a building.

Abstract: An apparatus includes a sample chamber constructed according to a design certified by the Department of Transportation for transporting fluids at a first pressure P1. A cylindrical sample compartment exists within the sample chamber. The sample compartment is designed to withstand the pressure P1. The cylindrical sample compartment has a cylindrical inner surface with a radius r and a height h. A hollow cylindrical sleeve is secured to the cylindrical inner surface of the sample compartment and has a wall of thickness t. The sample chamber is capable of transporting fluids at a second pressure P2. P2 is higher than P1.

Abstract: A solar collector system is for support in a building opening to furnish heated air to the interior of the building. The solar collector system includes a collector shell supported at the opening and including a front heating chamber, at least one air intake channel and at least one air outlet channel and a fan disposed within the collector shell for providing a closed loop air circulation from the air intake channel, through the heating chamber and to the air outlet channel. The front heating chamber is defined in part by a parabolic reflector having a focal point facing out from the heating chamber. A heat exchanger is disposed within the parabolic reflector for absorbing solar energy directed to the heating chamber.

Abstract: A receiver for a solar power generation plant with a plurality of heliostats is provided. The solar receiver is mounted above the heliostats on a tower and faces downwardly towards the heliostats. The solar receiver includes a plurality of receiver modules mounted on a frame which allows individual columns of receiver modules to pivot inwardly and into the tower for service.

Abstract: A solar receiver having a radiation capturing element for capturing solar radiation passing through a radiation receiving aperture into a cavity formed by the radiation capturing element, the aperture having a first diameter and the cavity having cylindrical walls of a second diameter, the second diameter being larger than the first diameter, preferably about twice as large. Furthermore, the length of the cavity is greater than the first diameter, preferably about twice as great.

Abstract: The present invention provides a process for absorbing solar energy and, simultaneously having a continuous control of the light admission making it possible to install the device in external openings of buildings and equipment, such as windows, shutters or skylights. The system comprises two frames which support plates of transparent material, between which it is possible to introduce a colourful solution coming from an external reservoir. Both frames are interconnected through a flexible membrane which allows the plates to be pushed against each other, making the window transparent, or pushed away interposing the colourful solution, which will make the window uniform and gradually translucent or opaque. The said liquid comes from a reservoir and the access to the gap between the plates through is obtained by means of a channel that separates the two frames, allowing the liquid to flow evenly into the whole surface, thus being a homogenous and adjustable darkening obtainable.

Abstract: A solar collector having two axis control and cogeneration capabilities is provided. The solar collector may have a primary collecting mirror, a second reflecting mirror, and a solar collector positioned adjacent to the primary mirror. The collector may realize both direct solar to electricity production via photovoltaic cells or the like, as well as heat collection generated by the collected solar energy. The collected heat may be transferred to a fluid which may be transferred for productive uses such as electricity production, heating, cooling, and the like.

Abstract: The invention relates to a device for collecting solar energy (1), characterized in that it includes at least one solar receiver (2) including at least one suspension of solid particles fluidized by a gas, each suspension circulating between an inlet and an outlet of the receiver (2), wherein the volume of particles is between 40% and 55% of the volume of the suspension, and the average size of the particles is between 20 and 150 ?m.

Abstract: The radiation-selective absorber coating for absorber tubes of parabolic trough collectors includes two or more barrier layers (24a, 24b); an infrared reflective layer (21) on the barrier layers (24a, 24b); at least one cermet absorption layer (22) above the infrared reflective layer (21) and an antireflection layer (23) above the at least one cermet absorption layer (22). The two or more barrier layers (24a, 24b) include a first barrier layer (24a) of thermally produced oxide and a second barrier layer (24b) arranged above it. The second barrier layer (24b) is a cermet material including at least one oxide compound and at least one metal. The oxide compound is aluminium oxide, silicon oxide, nickel oxide and/or chromium oxide. The metal is molybdenum, nickel, tungsten and/or vanadium. The invention also includes an absorber tube with the absorber coating on it.

Abstract: In a “once-through” configuration, feedwater is pressurized, preheated, and evaporated in a series of pipes exposed to concentrated solar energy to produce a water-steam mixture for direct distribution to an industrial process such as enhanced oil recovery or desalination. Active steam quality management, in a preheat mode, vents warm/hot water and low-quality steam to a return vessel where steam is recondensed via contact with water and fed back in as feedwater. In an operating mode, the venting is disabled, and high-quality steam is directed as an outlet stream. Inlet water flowrate and outlet valves are managed to reduce effects of variation in the solar energy. A steam generator continuous piping system uses a single continuous receiver pipe that is illuminated by segmented parabolic mirrors enabled to track the sun to reduce high-temperature fouling. Provisions for steam generator piping recurring maintenance are provided.

Abstract: One embodiment of the invention relates to a light concentrator apparatus including a reflector with an open substantially hemispherical reflecting surface characterized by a radius R, and an aperture for admitting light onto the hemispherical reflecting surface. The light concentrator apparatus further includes a movable elongated light collector having a first end located proximal to the reflecting surface; and extending along a longitudinal axis in a direction substantially normal to the reflecting surface to a second end. The light concentrator further includes a tracker configured to move the first end of the collector to points proximal to the reflecting surface.

Abstract: An apparatus includes a closed loop circuit that has a concentrated solar receiver and a particulate thermal transfer media moveable through the closed loop circuit. The particulate thermal transfer media has a melting temperature of greater than 600° C./1112° F. A heat exchanger is in communication with the particulate thermal transfer media.

Abstract: A protective transparent enclosure (such as a glasshouse or a greenhouse) encloses a concentrated solar power system. The concentrated solar power system includes one or more solar concentrators and one or more solar receivers. Thermal power is provided to an industrial process, electrical power is provided to an electrical distribution grid, or both. In some embodiments, the solar concentrators are parabolic trough concentrators with one or more lateral extensions. In some embodiments, the lateral extension is a unilateral extension of the primary parabolic trough shape. In some embodiments, the lateral extensions are movably connected to the primary portion. In some embodiments, the lateral extensions have a focal line separate from the focal line of the base portion. In some embodiments, the greenhouse is a Dutch Venlo style greenhouse.

Abstract: A protective transparent enclosure (such as a glasshouse or a greenhouse) encloses a concentrated solar power system. The concentrated solar power system includes one or more solar concentrators and one or more solar receivers. Thermal power is provided to an industrial process, electrical power is provided to an electrical distribution grid, or both. In some embodiments, the solar concentrators are parabolic trough concentrators with one or more lateral extensions. In some embodiments, the lateral extension is a unilateral extension of the primary parabolic trough shape. In some embodiments, the lateral extensions are movably connected to the primary portion. In some embodiments, the lateral extensions have a focal line separate from the focal line of the base portion. In some embodiments, the greenhouse is a Dutch Venlo style greenhouse.

Abstract: A hybrid solar collector is disclosed having a passive solar collector unit and active photovoltaic panels. The inclination angle of the photovoltaic panels is optimized by linking the panels to the passive unit and its associated tracking controls.

Abstract: A solar energy conversion system may include a receiver with a first heat transfer fluid channel having at least two opposite sides. Each side may present an external surface facing in a direction opposite to that of the external surface of the other opposite side. Each side may be configured to contact a heat transfer fluid carried in the first heat transfer fluid channel. A heliostat field may be configured to direct solar energy to each of the at least two opposite sides during the course of a day such that a thermal stress tending to bend the channel remains below a specified level.

Abstract: A solar reflective assembly includes a plurality of reflective segments radially configured to collectively at least partially define a dish-shaped reflector having a center axis, each reflective segment having a generally conical shape and being discontinuous relative to the conical shape of an adjacent reflective segment, and an elongated receiver having a length generally extending in a direction of the center axis. Each reflective segment reflects and focuses sunlight on the receiver along the length of the receiver.

Abstract: A concentrating solar energy device for use in buildings is configured to share structural elements with a building for cost savings. The device incorporates a shallow cylindrical trough mirror comprising mirrored sheets that are conformed to curved rafters, a receiver that is moveable within the cumulative area of focus of the cylindrical trough mirror, a secondary mirror integrated with the receiver that augments solar energy collection, and parallel linear tracking assemblies that move the receiver and that mount to a building's side walls.

Abstract: It is to heighten the heat collecting efficiency of a linear type solar heat collecting apparatus. A plurality of reflection lines and one reception line are included. The reflection lines are arranged in parallel substantially in the south-north direction on earth. Each reflection line L1, L2, . . . has a heliostat 1. The heliostat 1 is composed of a plurality of mirror segments disposed in series on each reflection line L1, L2, . . . . The reception line C extends in the east-west direction perpendicular to the reflection lines L1, L2, . . . , and is disposed at a predetermined position above the reflection lines L1, L2, . . . The reception line C has a single receiver. The mirror segments disposed on each reflection line L1, L2, . . . radiate reflected light of sunlight that has impinged on the mirror surface toward the reception line C. The receiver 2 disposed on the reception line C collects the heat of the reflected light of sunlight radiated from the mirror segments disposed on each reflection line.

Abstract: A solar water heating and cooling system including a solar energy collection assembly having a heat absorbing element, a heat exchanger and a shield. The system also includes a cooling assembly, the cooling assembly is integral with the shield. The system has a check valve in fluid communication with the solar collection assembly and the cooling assembly, and a fluid pump in fluid communication with the solar energy collection assembly. A working fluid is disposed within the solar energy collection assembly, the cooling assembly, the check valve and the fluid pump. A cooling loop is defined by the solar energy collection assembly, the cooling assembly and the check valve. When the fluid pump is off, the working fluid circulates through the cooling loop, but when the fluid pump is on, the working fluid circulates through a heating loop that is defined by the solar energy collection assembly and the fluid pump.

Abstract: A system of passively heating water using solar energy and an absorber formed from two identical halves of molded darkened glass that are fused together. The absorber is essentially a plurality of black glass struts that are sandwiched between two black glass surfaces. The struts act as baffle plates and define cells. Water is carried through the system via the thermosiphoning effect.

Abstract: In a solar concentrator of a type having a curved mirror adapted to focus light onto an energy collecting body mounted at the mirror's focal axis, an alignment correction apparatus and method includes a linear array of light detectors adapted to be mounted at a bottom of and across a centerline of the curved mirror so as to intercept the shadow cast by the energy collecting body mounted along the focal axis. Outputs of each of the detectors are measured and plotted according to an order of arrangement of the light detectors on the array. The output results in a dip across adjacent detectors when a shadow falls across the array. A shadow detection means is adapted to determine a center point of the dip and correction means are configured to output a correction command if the center point is different from an optimal position.

Abstract: A solar receiver for a thermal power plant including a plurality of absorber modules, each absorber module including at least one face configured to be illuminated by a solar flux, wherein the modules are arranged side by side forming a paving. Each absorber module further includes its own fluid circuit in which a fluid to be heated by the solar flux can flow, the fluid circuits of the absorber modules being connected to one another.

Abstract: A boiler for a solar receiver includes a panel support structure. A boiler stay is operatively connected to the panel support structure. A panel stay is slideably engaged to the boiler stay. A boiler panel is operatively connected to the panel stay with the panel stay being affixed to a plurality of tubes of the panel. The boiler stay and panel support assemblies are configured and adapted to slide with respect to one another to accommodate thermal expansion of the boiler panel. In certain embodiments, a pin connects the boiler stay and the panel stay, wherein the pin is removable for installation and removal of the panel from the support structure.

Abstract: A parabolic trough solar collector system has a parabolic reflector used with an independently supported collector tube. The parabolic reflector has a reflective surface formed on a reflective surface support structure, supported by a circular support beam. This assembly rests on a plurality of support and drive rollers supported by a roller support arm, supported by a roller support column. The parabolic reflector assembly rotates against the rollers along a single axis to maintain a focus line of the parabolic reflector surface at the same location as the center of the circle described by the outer edge of the circular support beam. Located at this same focus line is the independently supported collector tube not attached to the parabolic trough reflector. The collector tube is supported on pipe roller hangers, which in turn are supported by a wire catenary system connected to support towers which straddle the parabolic reflector.

Abstract: Apparatus and methods related to solar energy are provided. Light concentrators are mechanically coupled and arranged as respective groups within a system. Groups are disposed along upper and lower levels. Lower level groups are aligned with respective gaps defined between upper level groups. Angular positioning of the light concentrators tracks the motion of the sun, resulting in varying gap widths. Light concentrators on the lower level receive varying amounts of sunlight accordingly, yet contribute to the overall energy yield from the system.

Abstract: The present invention relates to a solar thermal system which has improved use efficiency, enables heat acquired in a heat-collecting unit to be quickly used for a heating and hot water supply load, and can be operated in a stable manner.

Abstract: A solar reflection apparatus (60) is disclosed comprising a rotatable reflection (assembly 20) and a drive mechanism (12) which is operable to drive rotation of the reflection assembly (20) at its axis of rotation. The reflection assembly (20) comprises a curved linear reflector (4) defining a focal axis F, a counter weight (17) operable to balance the self weight of the reflector (4), and a support structure (15) via which the reflector (4) and counter weight (17) are rotatably mounted at locations along the focal axis F of the reflector (4). A solar collection apparatus (2) is also disclosed comprising a solar reflection (apparatus 60) as disclosed above and a heat collecting element (6), fixedly mounted along the focal axis F of the reflector (4).

Abstract: An energy collecting module for assembling, together with a plurality of similar energy collecting module, a modular energy collecting system. The energy collecting module comprises a fluid channel having a lumen for conducting fluid from a first connectable opening to a second connectable opening and an energy collecting element mounted in front of the fluid channel for concentrating radiation along the fluid channel.

Abstract: An auto-tracking sun solar energy power generator. The power generator includes an eight-diagram-shaped photovoltaic power generator of 8.8 multiples, an eight-diagram-shaped thermal energy generator of 30-50 multiples, a Striling external-combustion photothermal power generator of an eight-diagram-shaped thermal energy generator and a wind-light mutual complementing power generator with the power more than 20 kW. The first three devices are eight-diagram-shaped and of multiple sun structure. The fourth device is a wind-light mutual complementing planar silicon batteries power generator. The first three devices comprise a named multiple suns machine and a named tracking sun machine. The multiple suns machine comprises a metal bracket and planar glass. The tracking sun machine comprises a mechanical drive assembly for tracking sun and a counter-weight.

Abstract: A solar concentration plant which uses water/steam as a fluid, in any thermodynamic cycle for the exploitation of process heat, comprising an evaporation subsystem, where saturated steam is produced, a superheater subsystem through which the steam reaches the required conditions of pressure and temperature at the turbine inlet, and an attemperation system interconnected by a drum. A field of heliostats is pointed towards either of the subsystems (evaporator or superheater), in such a way to control both the pressure within the drum and the outlet temperature of the superheated steam.

Abstract: Non-evaporable getter pump assembly (1) for a vacuum solar thermal panel, ensuring a quick and efficient heating of the getter pump, comprising: a solar receiver plate (2), having an outer side (20) predisposed for absorbing solar radiation; at least a first supporting plate (3a); at least a non-evaporable getter element (4) interposed between an inner side (21) of the solar receiver plate (2) and the first supporting plate (3a); and holding means for pressing the solar receiver plate (2) and the first supporting plate (3a) against one another sandwiching the non-evaporable getter element (4) between the two plates (2, 3a).

Abstract: Apparatus and methods related to solar energy are provided. A system includes a solar array supported to be angularly repositionable. A shuttle and linkage arrangement is coupled to the solar array. Thermally activated actuators sequentially control the linear translation of the shuttle such that the solar array is incrementally angularly repositioned over the course of a daylight period. Concentrated solar energy is used to heat the actuators in their sequential order. Systems for generating electrical and/or thermal energy, embodied as panels or other form-factors, are contemplated.

Abstract: A solar-tower system includes a raised solar receiver disposed on a tower and a mirror array including multiple flat mirrors for reflecting sunlight onto the raised receiver. The mirror array is disposed on a carousel-type platform that is rotatable around a vertical axis, and the raised receiver is maintained at a substantially fixed position relative to the mirror array for all rotational positions of the platform. A solar azimuth tracking controller controls the platform's rotational position to track the sun's azimuth angle such that sunlight shines on the mirror array from a fixed apparent azimuth angle at all times during daylight hours. Each flat mirror pivots around a corresponding unique axis, and a solar elevation tracking controller individually controls each mirror's pivot position to track the sun's elevation angle such that sunlight is accurately reflected onto the raised solar receiver at all times during daylight hours.

Abstract: A method for harvesting solar power by concentrating sunlight onto a raised solar receiver disposed on a tower. The method involves rotating a mirror array made up of multiple flat mirrors as a unit around a vertical axis such that sunlight shines on the mirror array from a fixed apparent azimuth angle at all times during daylight hours, and controlling each mirror's pivot position to track the sun's elevation angle such that sunlight is accurately reflected onto the raised solar receiver at all times during daylight hours. In one embodiment the mirror array is disposed on a roundabout-type platform whose rotational position is controlled to track the sun's azimuth angle and the raised receiver is maintained at a substantially fixed position relative to the mirror array for all rotational positions of the platform.

Abstract: An offshore vessel embodies a mobile buoyant energy recovery system enabled to extract energy from solar power. An exemplary energy recovery system comprises concentrating solar thermal power systems (CSP) or concentrating photovoltaic power (CPV) systems on the deck of the vessel. Within the vessel hull, ballast water serves multiple purposes. The ballast not only stabilizes the vessel, but also provides reactant for hydrogen electrolysis or ammonia synthesis, or steam for a turbine. For CPV systems the ballast conducts heat as a coolant improving the efficiency and durability of photovoltaic cells. For CSP systems the ballast water becomes superheated steam through a primary heat exchanger in the concentrator. In some embodiments, some steam from the CSP primary heat exchanger or from the CPV coolant system undergoes high-pressure electrolysis of enhanced efficiency due to its high temperature.

Abstract: This invention provides a solar fluid heating assembly that generally increases efficiency by reflecting the sun's energy onto heat generating surfaces that face away from the sun. It also provides an aesthetic structure that is readily installed in a variety of outdoor settings and can be used as a boundary fence in certain applications. In an illustrative embodiment, the solar heater comprises one or more conduits and a reflective mechanism, such that in use, heat energy falls onto a front surface of the conduit, thereby heating water or another fluid within the conduit, and heat energy is reflected by the reflective mechanism onto another surface of the conduit, thereby further heating the fluid within the conduit.

Abstract: A solar boiler includes a boiler support defining an axis along an inboard-outboard direction. A hanger rod is rotatably mounted to the boiler support. A bracket is rotatably mounted to the hanger rod, and a solar boiler panel is mounted to the bracket. The solar boiler panel defines a longitudinal axis that is substantially perpendicular with the axis of the boiler support. The hanger rod connects between the boiler support and the bracket to support the weight of the solar boiler panel from the boiler support. The hanger rod and bracket are configured and adapted to maintain a substantially constant orientation of the bracket during inboard and outboard movement of the bracket relative to the boiler support.

Abstract: An energy transmitting solar panel (12, 22, 32, 42, 52, 62) intended for invisible incorporation into a building, a part or component thereof, behind and in thermal contact with a climate shield (12, 21, 31, 41, 51, 61) on said building, a part or component thereof, is made of a heat-conducting material and has a substantial heat transmitting surface area and at least one through-going fluid impervious channel or duct (15, 25, 35, 45, 55, 65) embedded in or integrally connected with said panel for the flow of an energy carrying-capable fluid therein. The solar panel is mounted below and close up to a climate shield of a building so that good thermal contact is established there between providing excellent transmission of converted sun radiation to an energy carrying-capable fluid in the fluid impervious channel or duct.

Abstract: Solar energy concentrating apparatus having an array of lenses to receive and concentrate the solar radiation towards a plurality of stationary targets. The lenses are supported on a moveable structure to enable the lenses to move laterally in the east-west and north-south directions. Each lens of the array is also configured to rotate about an axis extending in the north-south direction. Drive means is coupled to a plurality of lateral and rotational movements mechanisms to orientate the lenses towards the target as the sun moves throughout the day and year.

Abstract: This invention relates to a fluid heating system, wherein the fluid is capable of being heated by means of solar energy, the fluid heating system including: an outer housing; an inner housing contained within the outer housing and including an absorbent material core located within the inner housing to define a flow passage between it and the walls of the inner housing; the absorbent material core being suitable for absorbing solar energy transmitted through the outer and inner housings; and wherein the outer housing; inner housing; and the absorbent material core are arranged such that solar energy is transferred through the fluid in the flow passage before being absorbed by the absorbent material core.

Abstract: A solar reflector assembly is provided for generating energy from solar radiation. The solar reflector assembly is configured to be deployed on a supporting body of liquid and to reflect solar radiation to a solar collector. A solar reflector assembly comprises an inflatable elongated tube having an upper portion formed at least partially of flexible material and a lower ballast portion formed at least partially of flexible material. A reflective sheet is coupled to a wall of the tube to reflect solar radiation. The elongated tube has an axis of rotation oriented generally parallel to a surface of a supporting body of liquid.

Abstract: The solar concentrator includes a base with a support frame that is rotatably connected thereto. A torsion box is tiltably mounted to the support frame to provide a wide range of movement of the torsion box and the finish surface thereon, which is preferably of a single plane parabolic shape that carries linear mirror strips. A receiver is mounted above the surface of the mirror strips at the focus of the parabola by a bracket to optimize reflection of radiation thereto. Plumbing transports liquid, such as water, through the receiver for heating thereof for various purposes, such as water desalinization. Thus, the solar concentrator is an optimized low cost and easy to manufacture solar concentrator.

Abstract: A solar concentration system and a solar collection and concentration system both comprising a wave generator immersed in a fluid and processes for collecting and/or concentrating solar energy are disclosed. The solar collection and concentration system comprises a vibrating ring or ring assembly (1001), a pole or column (1009), a liquid medium used as a reflective surface, a vibration or actuation element (1001, 1003) and an energy absorption, transfer, or converting element (1019, 1020).

Abstract: The invention relates to a thermal energy storage system comprising at least one thermal reservoir and at least one thermal energy transfer means that, at least at times, are able to transfer thermal energy from at least one first section of the thermal reservoir to at least one second section of the thermal reservoir. The invention also relates to a method changing the energy distribution of a thermal reservoir wherein thermal energy is transferred from at least one first section of the thermal reservoir to at least one second section of the thermal reservoir.

Abstract: A solar water heating arrangement comprising a solar water heating element and a hot water storage vessel having a heat insulated internal volume for storage of hot water for use by a user and conduits linking them to form a fluid circulation loop is improved by providing a further, intermediate storage tank linked to the solar water heating arrangement to form another fluid circulation loop whereby the flow of fluid from the solar water heating element to the hot water storage vessel and the intermediate storage tank through the respective fluid circulation loops may be controlled for enhanced heat capture efficiency and heat storage management.

Abstract: A system for switching a focus position comprises a plurality of active focus-switch devices capable of changing a focal length for several times, a plurality of objects to be focused, a plurality of incident light beams passing through the active focus-switch devices and then being focused on the objects to be focused, and at least one external power supply electrically connected to the active focus-switch devices, wherein the external power supply is electrically conducted or not conducted to the active focus-switch devices, and the plural incident light beams are focused on the objects to be focused by the active focus-switch devices, or the plural incident light beams passing through the active focus-switch device are projected to the outside in form of a plurality of exit light beams parallel to the plural incident light beams.