Wide angle solar concentrator

Abstract

A non-imaging optical collecting and concentrating apparatus for use in i.e., optical communications, passive lighting, and solar power applications that is relatively immune from optical incidence angle(s) and therefore does not need to track the movement of the sun to efficiently collect and concentrate optical energy is described. The apparatus includes a tubular support structure having a source-facing entrance and an energy-outputting exit. An interior surface of the structure includes a scattering, reflecting and/or diffractive medium to direct incident energy toward an exit of the tubular structure, such that the rays exiting the tube are more collimated and substantially more parallel to the axis of the tube. The collimated beam is then focused or directed by a lens or similar optical element toward a point where the energy may be collected by a detector, optical fiber, or other collection means.

1 . An apparatus for collecting solar or other optical radiation comprising: 
 a tubular structure, defining an interior surface; and    a diffracting medium, disposed on the interior surface of the tubular structure;    such that light rays striking the interior of the tubular structure are directed to a common point, said common point being substantially an exit aperture of the tubular structure, along ray paths which are substantially more aligned with the axis of the tube than the paths along which the rays enter the tube;    a lens or functional equivalent optic, located at a point past the exit aperture of the tube, relative to the direction of propagation of rays;    such that the rays exiting the tube will be directed by the lens to a collection point, such collection point being essentially the focal point of the lens or similar optic.    
   
   
       2 . The apparatus of  claim 1 , where the diffractive surface of the tube is made from a surface relief grating.  
   
   
       3 . The optical apparatus of  claim 2 , wherein the surface relief grating is designed to diffract principally in a direction away from the specular reflection from the surface.  
   
   
       4 . The optical apparatus of  claim 3 , where the surface grating uses any combination or superposition of triangular, sinusoidal, step width, or step height variations to achieve the desired diffraction characteristic.  
   
   
       5 . The optical apparatus of  claim 1 , where the diffractive surface of the tube is made from a volume hologram or other periodic refractive index structure.  
   
   
       6 . The apparatus of  claim 1 , where the diffractive surface of the tube is made from a photonic bandgap, moth-eye, or other subwavelength, periodic, or quasi-periodic, diffractive or preferentially scattering structure.  
   
   
       7 . The optical apparatus of  claim 1 , where the tubular structure is designed to preferentially reflect or diffract light through geometric variations such as flared ends, tapered ends, or curved sides.  
   
   
       8 . The optical apparatus of  claim 1 , where the lens or focusing optic is replaced or used in conjunction with a transparent tapered structure located inside the tube to extract or guide light from inside the tube.  
   
   
       9 . The optical apparatus of  claim 1 , where a diffusing element, diffraction grating, or similar device is used to more evenly distribute light over the collection area.  
   
   
       10 . A method of collecting solar or other optical energy comprising the steps of: 
 receiving the optical energy on a substantially tubular structure having a diffractive surface for receiving the optical energy;    directing the optical energy by scattering, reflecting, coherently reflecting, diffracting, or any combination thereof, to a common point which is substantially an exit point of the tubular structure, such that the rays exiting the tubular structure are substantially more parallel to the axis of the tube than the rays entering it;    focusing or otherwise directing the rays exiting the tubular structure using a lens or similar optical instrument to a collecting point, said collecting point being essentially a focal point of the lens;    collecting the optical energy into a collector positioned at the collecting point.    
   
   
       11 . The method of  claim 10 , where the diffractive surface of the tubular structure is made from a surface relief grating.  
   
   
       12 . The method of  claim 11 , wherein the surface relief grating is designed to diffract principally in a direction away from the specular reflection from the surface.  
   
   
       13 . The method of  claim 12 , where the surface grating uses any combination or superposition of triangular, sinusoidal, step width, or step height variations to achieve the desired diffraction characteristic.  
   
   
       14 . The method of  claim 10 , where the diffractive surface of the tube is made from a volume hologram or other periodic refractive index structure.  
   
   
       15 . The method of  claim 10 , where the diffractive surface of the tube is made from a photonic bandgap, moth-eye, or other subwavelength, periodic, or quasi-periodic, diffractive or preferentially scattering structure.  
   
   
       16 . The method of  claim 10 , where the tubular structure is designed to preferentially reflect or diffract light through geometric variations such as flared ends, tapered ends, or curved sides.  
   
   
       17 . The method of  claim 10 , where the diffractive surface of the tube is made from a volume hologram or other periodic refractive index structure.  
   
   
       18 . The method of  claim 10 , where the lens or focusing optic is replaced or used in conjunction with a transparent tapered structure located inside the tube to extract or guide light from inside the tube.  
   
   
       19 . The method of  claim 10 , where a diffusing element, diffraction grating, or similar device is used to more evenly distribute light over the collection area.  
   
   
       20 . An optical collector/concentrator comprising: 
 a curved, tubular means for supporting a scattering, reflective, or diffractive surface or any combination thereof wherein said curved supporting means defines an interior surface; and    a means for preferentially directing light rays, disposed upon the supporting means of the tubular support structure;    such that light rays striking the interior surface of the tubular support means are directed to a common point, said common point being substantially an exit aperture of the tubular support means;    a means for directing the rays exiting the tubular support means to a collection point, said collection point being essentially the focal point of the focusing or directing means;    such that optical energy directed to the collection point may be collected by a collection device or other means for collecting the optical energy.