Tracking Concentrator Employing Inverted Off-Axis Optics and Method

Abstract

Solar concentrators are arranged in an array to define an input aperture such that the solar collector is positionable to face the input aperture of the concentrators skyward. An input axis of rotation extends through the aperture in the skyward direction, and a focus region is smaller than the aperture. Each concentrator includes at least one optical arrangement that is supported for rotation about the input axis for tracking the sun within a predetermined range of positions of the sun using no more than the rotation of the optical arrangement around the input axis. An optical concentrator is described in which a receiving direction extends at an acute angle from an optical axis and in one azimuthal direction outward from the optical axis such that a component of the concentrator is rotatable about the optical axis for alignment to receive input light. A previously unknown inverted off-axis lens is described.

1 . A solar collector comprising:
 one or more solar concentrators arranged in an array such that each of said concentrators is in a fixed position with a fixed alignment in said array and each of said concentrators is configured to define (i) an input aperture having an input area such that the solar collector is positionable to face the input aperture of each concentrator in a skyward direction such that said input aperture is oriented to receive sunlight from the sun, (ii) an input axis of rotation that extends through said aperture in said skyward direction, and (iii) a focus region that is substantially smaller than said aperture area, and each of said concentrators includes an optical assembly having at least one optical arrangement that is supported for rotation about said input axis for tracking the sun within a predetermined range of positions of said sun using no more than said rotation of the optical arrangement around the input axis such that said rotation does not change the direction of the aperture from said skyward direction,   wherein for any specific one of said positions within said predetermined range of positions, said optical arrangement is rotatably oriented, as at least part of said tracking, at a corresponding rotational orientation as at least part of concentrating the received sunlight within said focus region, for subsequent collection and use as solar energy.   
     
     
         2 . The solar collector of  claim 1  wherein for said specific one of said positions of said sun, a rotational misalignment caused by rotating the optical arrangement away from said corresponding rotational orientation causes at least some of said received sunlight to be directed outside of said focus region. 
     
     
         3 . The solar collector of  claim 1  wherein said optical arrangement serves as an input arrangement for initially receiving the sunlight, and said optical assembly includes an additional optical arrangement following said input arrangement to accept the sunlight from the input arrangement and configured for rotation about an additional axis of rotation, and said input arrangement and said additional arrangement are configured to cooperate with one another in performing said tracking based at least in part on a predetermined relationship between (i) said rotation of said input arrangement about said input axis of rotation and (ii) rotation of said additional arrangement about said additional axis of rotation to focus the received sunlight into the focus region. 
     
     
         4 . The solar collector of  claim 3  wherein said additional axis of rotation and said input axis of rotation are at least approximately parallel with one another. 
     
     
         5 . The solar collector of  claim 3  wherein said additional axis of rotation and said input axis of rotation are collinear with one another. 
     
     
         6 . The solar collector of  claim 3  wherein said input optical arrangement is configured for bending the received sunlight for acceptance by said additional optical arrangement, and said additional optical arrangement is configured for accepting and redirecting the bent light to cause said focusing. 
     
     
         7 . The solar collector of  claim 3  including a group of two or more of said solar concentrators and a drive mechanism rotatably couples all of said input arrangements in said group to collectively rotate all of said input arrangements while maintaining, during said tracking, at least approximately the same rotational orientation for all of the input arrangements as at least part of causing the optical assemblies in the group to track the sun in a synchronized way. 
     
     
         8 . The solar collector of  claim 7  wherein said drive mechanism is further configured for rotatably coupling all of said additional arrangements in said group to collectively rotate all of said additional arrangements while maintaining, during said tracking, at least approximately the same rotational orientation for all of the additional arrangements as at least part of causing the optical assemblies in the group to track the sun in said synchronized way. 
     
     
         9 . The solar collector of  claim 8  wherein said additional arrangement and said input arrangement of each concentrator are rotatably coupled with one another through said drive arrangement such that a first amount of rotation of one of said input arrangement or said additional arrangement causes a second amount of rotation in the other one of the input arrangement or the additional arrangement, and the predetermined relationship is maintained throughout said tracking at least in part as a result of said coupling. 
     
     
         10 . The solar collector of  claim 3  wherein said optical assembly is configured to define a receiving direction as a vector that is characterized by a predetermined acute receiving angle with respect to the input axis such that the input axis and the receiving direction define a plane, and which receiving direction extends in one azimuthal direction outward from the input axis in said plane, such that said receiving direction is adjustable, based on a coordinated rotation of said input arrangement and of said additional arrangement, for performing said tracking of said sun. 
     
     
         11 . The solar collector of  claim 10  wherein said input optical arrangement is configured for bending the received sunlight for acceptance by said additional optical arrangement, and said additional optical arrangement is configured for accepting and redirecting the bent light to cause said focusing. 
     
     
         12 . The solar collector of  claim 3  wherein said input arrangement defines an at least generally planar configuration, and said input arrangement includes a planar input surface that defines said input aperture. 
     
     
         13 . The solar collector of  claim 12  wherein said input arrangement is configured for bending the received light rays. 
     
     
         14 . The solar collector of  claim 13  wherein said additional arrangement is a CPC following said input arrangement to accept the light rays from the input arrangement, and the CPC is configured to cause said focusing. 
     
     
         15 . The solar collector of  claim 14  wherein said CPC is a reflective CPC configured for performing said focusing by reflecting the light rays received from the input arrangement to the focus region. 
     
     
         16 . The solar collector of  claim 13  wherein said optical assembly includes an IOA following said input arrangement to accept the light rays from the input arrangement, and the IOA is configured to cause said focusing. 
     
     
         17 . The solar collector of  claim 1  wherein said optical arrangement serves as an input arrangement for initially receiving the sunlight, and said optical assembly includes an additional optical arrangement following said input arrangement to accept the sunlight from the input arrangement and configured for rotation about an additional axis of rotation, and said input arrangement and said additional arrangement are configured to cooperate in performing said tracking based at least in part on said rotation of said input arrangement about said input axis of rotation. 
     
     
         18 . The solar collector of  claim 17  wherein said optical assembly is configured to define a receiving direction as a vector that is characterized by a predetermined acute acceptance angle with respect to the input axis such that the input axis and the receiving direction define a plane, and which receiving direction extends in one azimuthal direction outward from the input axis in said plane, such that said receiving direction is rotatably adjustable, based at least in part on said rotation of said input arrangement. 
     
     
         19 . The solar collector of  claim 18  wherein said input optical arrangement is configured for bending the received sunlight for acceptance by said additional optical arrangement, and said additional optical arrangement is configured for accepting and redirecting the bent light to cause said focusing. 
     
     
         20 . The solar collector of  claim 17  wherein said input arrangement defines an at least generally planar configuration, and said input arrangement includes a planar input surface that defines said input aperture. 
     
     
         21 . The solar collector of  claim 20  wherein said input arrangement is configured for bending the received light rays for acceptance by said additional arrangement. 
     
     
         22 . The solar collector of  claim 21  wherein said additional arrangement is a CPC following said input arrangement to accept the light rays from the input arrangement, and the CPC is configured to cause said focusing. 
     
     
         23 . The solar collector of  claim 22  wherein said CPC is a reflective CPC configured for performing said focusing by reflecting the light rays accepted from the input arrangement to the focus region. 
     
     
         24 . An optical concentrator comprising
 an optical assembly having one or more optical arrangements including an input optical arrangement, and said optical assembly is configured for   defining (i) an input aperture having an input area for receiving a plurality of input light rays, (ii) an optical axis passing through a central region within said input aperture, (iii) a focus region having a surface area that is substantially smaller than the input area and is located at an output position along said optical axis offset from the input aperture such that said optical axis passes through said focus region, and (iv) a receiving direction defined as a vector that is characterized by a predetermined acute receiving position with respect to said optical axis such that the optical axis and the receiving direction define a plane, and which receiving direction extends in one azimuthal direction outward from the optical axis in said plane such that at least the input arrangement is rotatable about the optical axis for alignment of the receiving direction to receive a plurality of input light rays that are each at least approximately antiparallel with said vector, and   thereafter, focusing the plurality of input light rays to converge toward said optical axis until reaching said focus region such that the input light is concentrated at the focus region.   
     
     
         25 . The optical concentrator  claim 24  wherein said focus region includes a given area and for at least some of said input light that is characterized by at least a particular amount of misalignment with the receiving direction, that input light is rejected by falling outside of the given area of the focus region. 
     
     
         26 . The optical concentrator of  claim 24  wherein said input arrangement defines an at least generally planar configuration, and said input arrangement includes a planar input surface that defines said aperture. 
     
     
         27 . The optical concentrator of  claim 26  wherein said optical assembly includes an additional optical arrangement following said input arrangement, and said input arrangement is configured for bending the received light rays for acceptance by said additional arrangement. 
     
     
         28 . The optical concentrator of  claim 27  wherein said additional arrangement is a CPC configured to accept the light rays from the input arrangement, and the CPC is configured to cause said focusing. 
     
     
         29 . The optical concentrator of  claim 27  wherein said CPC is a reflective CPC configured for performing said focusing by reflecting the light rays received from the input arrangement to the focus region. 
     
     
         30 . The optical concentrator of  claim 27  wherein said additional arrangement is an IOA configured to accept the light rays from the input arrangement, and the IOA is configured to cause said focusing. 
     
     
         31 . The optical concentrator of  claim 30  wherein said IOA is configured for selective rotation about said optical axis, and said input arrangement and said IOA are configured to cooperate with one another in performing said receiving and said focusing based at least in part on (i) said rotation of said input arrangement about said optical axis and (ii) said rotation of said IOA. 
     
     
         32 . An inverted off-axis lens, comprising:
 an optical arrangement having an at least generally planar configuration defining (i) a planar input surface having an input surface area and (ii) an axis of rotation that is at least generally perpendicular thereto; and   said optical arrangement is configured for   defining an acceptance direction as a vector that is characterized by a predetermined acute acceptance angle with respect to said axis of rotation such that the axis of rotation and the acceptance direction define a plane, and which acceptance direction extends in one fixed azimuthal direction outward from the axis rotation in said plane such that the optical arrangement is rotatable about the axis for alignment of the acceptance direction to accept a plurality of input light rays that are each at least approximately antiparallel with said vector, and   thereafter, transmissively passing the plurality of input light rays through said optical arrangement while focusing the plurality of input light rays to converge toward one another until reaching a focus region that is substantially smaller than the input surface area such that the input light is concentrated at the focus region.   
     
     
         33 . The inverted off-axis lens of  claim 32  wherein said focus region includes a given area and for at least some of said input light that is characterized by at least a particular amount of misalignment with the acceptance direction, that input light is rejected by falling outside of the given area of the focus region. 
     
     
         34 . The inverted off axis lens of  claim 32  wherein said focal region is located along said axis of rotation offset from the input surface area such that said axis of rotation passes through said focal region. 
     
     
         35 . The inverted off axis lens of  claim 32  wherein said optical arrangement further defines an output surface that is at least generally parallel with said input surface and spaced therefrom by a thickness, and at least part of said thickness refracts said plurality of input light rays to cause the focusing of the light rays. 
     
     
         36 . The inverted off axis lens of  claim 32  wherein said optical arrangement is integrally formed of an optical material. 
     
     
         37 . The inverted off axis lens of  claim 36  wherein said optical arrangement includes a plurality of optical prisms to accept and focus said input light rays. 
     
     
         38 . The inverted off axis lens of  claim 35  wherein said optical arrangement includes a plurality of optical prisms that are configured to cooperate with one another to accept and the focus said input light rays, and the prisms are integrally formed of an optical material. 
     
     
         39 . The inverted off axis lens of  claim 38  wherein at least a subset of said plurality of prisms is integrally formed with said input surface. 
     
     
         40 . The inverted off axis lens of  claim 38  wherein at least a subset of said plurality of prisms is integrally formed with said output surface. 
     
     
         41 . The inverted off axis lens of  claim 38  wherein a first subset of said plurality of prisms is integrally formed with said input surface, and a second subset of said plurality of prisms is integrally formed with said output surface, 
     
     
         42 . The inverted off axis lens of  claim 41  wherein said first and second subsets of prisms are cooperatively configured to cooperate with one another for accepting and focusing said input light rays, and wherein said first subset of prisms is configured for bending the input light rays for acceptance by said second set of prisms, and said second subset of prisms is configured to cause said focusing of said input light rays. 
     
     
         43 . A solar concentrator for collecting and concentrating a plurality of mutually parallel incoming rays of sunlight, said solar concentrator including the inverted off axis lens of  claim 32  arranged in a series relationship following an input optical arrangement with the input surface of the off axis lens facing towards the input arrangement, and the inverted off axis lens and the input arrangement are each configured for selective rotation to cooperate with one another such that
 the input arrangement initially receives said incoming light rays and bends the incoming light rays to produce intermediate light rays for acceptance by said inverted off-axis lens such that the intermediate light rays are at least approximately oriented antiparallel to said acceptance direction, and   said inverted off axis lens is aligned for accepting said intermediate light rays such that said intermediate light rays serve as said input light rays for said inverted off axis lens and the inverted off axis lens concentrates the intermediate light rays at said focus region of said inverted off-axis lens.   
     
     
         44 . The solar concentrator of  claim 43  wherein said input arrangement is aligned with said axis of rotation, and said inverted off axis lens and said input arrangement are configured to cooperate with one another to define a receiving direction as a vector that is characterized by a predetermined acute acceptance angle with respect to the axis of rotation such that the axis of rotation and the receiving direction define a plane, and which receiving direction extends in one azimuthal direction outward from the axis of rotation in said plane, such that said receiving direction is rotatably adjustable, based on a coordinated rotation of said input arrangement and of said additional arrangement. 
     
     
         45 . The solar concentrator of  claim 43  wherein said input arrangement is concentrically aligned on said axis of rotation of said inverted off axis lens such that said selective rotation of said input arrangement revolves around said axis of rotation. 
     
     
         46 . The solar concentrator of  claim 45  wherein said input arrangement includes an input axis of rotation that is skewed with respect to said axis of rotation of said inverted off axis lens such that said input arrangement is tiltable toward the sun. 
     
     
         47 . The solar collector of  claim 44  including a receiver following said inverted off-axis lens, said receiver having a receiving surface facing towards the off axis lens and aligned such that the receiving surface at least partially overlaps said focus region, and said receiver is configured such that at least some of the concentrated input light is absorbed by said receiver and converted into a form of energy. 
     
     
         48 . The solar collector of  claim 47  wherein said receiver is configured for converting the absorbed input light into electrical energy as said form of energy. 
     
     
         49 . The solar collector of  claim 48  wherein the receiver is configured for converting the absorbed light into thermal energy as said form of energy. 
     
     
         50 . The solar collector of  claim 49  wherein said receiver is in thermal communication with a fluid and said receiver is configured such that at least a portion of said thermal energy is transferred to said fluid. 
     
     
         51 . The solar collector of  claim 50  wherein said receiver is configured for passing a liquid therethrough, and at least some of said thermal power is transferred to said liquid for subsequent use outside of said receiver. 
     
     
         52 . A multi-element inverted off-axis optical assembly, comprising:
 an optical assembly having two or more optical arrangements including a first arrangement that defines (i) an input aperture having an input area and (ii) an axis of rotation that is at least generally perpendicular thereto; and   said optical arrangements are configured to cooperate with one another for   defining an acceptance direction as a vector that is characterized by a predetermined acute acceptance angle with respect to said axis of rotation such that the axis of rotation and the acceptance direction define a plane, and which acceptance direction extends in one azimuthal direction outward from the axis of rotation in said plane, and at least said first arrangement is supported for motion that is limited to rotation about said axis of rotation for alignment of the acceptance direction to accept said plurality of input light rays that are each at least approximately antiparallel with said vector, and   thereafter, focusing the plurality of input light rays to converge toward one another until reaching a focus region that is substantially smaller than the input surface area such that the input light is concentrated at the focus region.   
     
     
         53 . The multi-element inverted off axis optical assembly of  claim 52  wherein said first arrangement is positioned for initially accepting said plurality of input light rays and said optical assembly includes a second optical arrangement following said first arrangement to collect the light rays from the first arrangement, and said first arrangement and said second arrangement are configured to cooperate in performing said accepting and said focusing based at least in part on said rotation of said first arrangement about said axis of rotation. 
     
     
         54 . The multi-element inverted off axis optical assembly of  claim 53  wherein said second optical arrangement is rotatably fixed such that the second optical arrangement is not rotatable. 
     
     
         55 . The multi element inverted off axis optical assembly of  claim 53  wherein said first arrangement and said second arrangement are fixedly attached to one another for simultaneous rotation such that said first arrangement and said second optical arrangement co-rotate together with one another as part of said alignment of said acceptance direction. 
     
     
         56 . The multi element inverted off axis optical assembly of  claim 53  wherein said first optical arrangement is configured for bending the received input light rays for acceptance by said second optical arrangement, and said second optical arrangement is configured for collecting and redirecting the bent light to cause said focusing. 
     
     
         57 . The multi-element inverted off axis optical assembly of  claim 53  wherein said second arrangement is a CPC. 
     
     
         58 . A solar concentrator for collecting and concentrating a plurality of mutually parallel incoming light rays, said solar concentrator including the multi-element inverted off axis optical assembly of  claim 52  arranged in a series relationship following an input arrangement that is aligned on said optical axis of said inverted off axis optical assembly with the input arrangement with the input surface of the off axis optical assembly facing towards the input arrangement, and the inverted off axis optical assembly and the input arrangement are each configured for selective rotation to cooperate with one another such that
 the input arrangement initially receives said incoming light rays and bends the incoming light rays to produce intermediate light rays for acceptance by said inverted off-axis optical assembly such that the intermediate light rays are at least approximately oriented antiparallel to said acceptance direction, and   said intermediate light rays serve as said input light rays for said inverted off axis optical assembly such that the inverted off axis optical assembly concentrates the intermediate light rays at said focus region of said inverted off-axis optical assembly.   
     
     
         59 . The solar collector of  claim 58  including a receiver having a receiving surface facing towards the off axis optical assembly and aligned such that the receiving surface at least partially overlaps said focus region, and said receiver is configured such that at least some of the concentrated input light is absorbed by said receiver and converted into power. 
     
     
         60 . A method for solar collection, said method comprising:
 arranging one or more solar concentrators in an array to position each of said concentrators in a fixed location with a fixed alignment in said array and configuring each of said concentrators for defining (i) an input aperture having an input area such that the solar collector is positionable to face the input aperture of each concentrator in a skyward direction with said input aperture oriented to receive sunlight from the sun, (ii) an input axis of rotation that extends through said aperture in said skyward direction, and (iii) a focus region that is substantially smaller than said input aperture;   configuring each of said concentrators with an optical assembly having at least one optical arrangement and supporting said optical arrangement for rotation about said input axis for tracking the sun within a predetermined range of positions of said sun using no more than said rotation of the optical arrangement around the input axis such that said rotation does not change the direction of the aperture from said skyward direction; and   for any specific one of said positions within said predetermined range of positions, rotatably orienting said optical arrangement, as at least part of said tracking, to a corresponding rotational orientation as at least part of concentrating the received sunlight within said focus region, for subsequent collection and use as solar energy.   
     
     
         61 . A method for focusing collimated light, said method comprising:
 configuring an optical IOA arrangement for defining (i) a planar IOA input surface having an input surface area and (ii) an axis of rotation that is at least generally perpendicular thereto; and   further configuring said optical IOA arrangement for   defining an acceptance direction as a vector that is characterized by a predetermined acute acceptance angle with respect to said axis of rotation such that the axis of rotation and the acceptance direction define a plane, and which acceptance direction extends in one fixed azimuthal direction outward from the axis rotation in said plane such that the optical arrangement is rotatable about the axis for alignment of the acceptance direction for accepting a plurality of input light rays, as said collimated light, that are each at least approximately antiparallel with said vector, such that said plurality of input light rays transmissively pass through said optical IOA arrangement and are concentrated by focusing the plurality of input light rays to converge toward one another until reaching a focus region that is substantially smaller than the input surface area.   
     
     
         62 . A method for concentrating a plurality of mutually parallel rays of sunlight, said method comprising:
 providing an input optical arrangement for initially receiving a plurality of incoming rays of sunlight;   positioning the optical IOA arrangement of  claim 61  in a series relationship following the input arrangement with the input surface of the optical IOA arrangement facing towards the input optical arrangement;   supporting the optical IOA arrangement and the input arrangement for selective rotation to cooperate with one another such that the input optical arrangement re-directs the incoming rays of sunlight to produce a set of intermediate rays of sunlight, for acceptance by said optical IOA arrangement, such that said intermediate rays of light are at least approximately oriented anti-parallel to said acceptance direction of said optical IOA arrangement; and   accepting said intermediate light rays with said optical IOA arrangement such that said intermediate light rays serve as said input light rays for said optical IOA arrangement and (ii) concentrating the intermediate light rays at said focus region of said inverted off-axis lens.