Nonimaging optical concentrators and illuminators

• US 5,971,551 A
• Filed: 07/07/1995
• Issued: 10/26/1999
• Est. Priority Date: 07/07/1995
• Status: Expired due to Term

• Current Assignee: ARCH Development Corporation (University of Chicago)
• Original Assignee: ARCH Development Corporation (University of Chicago)
• Inventors: Jenkins, David Gerard, Winston, Roland
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US08/499,403
• Time in Patent Office: 1,572 Days
• Field of Search: 359/851, 359/853, 359/868, 359/869, 359/364, 359/726, 359/727, 359/730, 126/683, 126/684, 126/688, 126/689, 126/690, 126/691, 126/692, 126/693, 126/694, 126/695, 126/698
• US Class Current: 359/868
• CPC Class Codes: F24S 2023/838 involutes
• CPC Class Codes: F24S 23/00 Arrangements for concentrating solar-rays for solar heat collectors
• CPC Class Codes: F24S 23/80 having discontinuous faces
• CPC Class Codes: G02B 5/10 with curved faces
• CPC Class Codes: Y02E 10/44 Heat exchange systems

Abstract

A nonimaging concentrator (or illuminator) of light. The concentrator (or illuminator) has a shape defined by dR/dφ=Rtanα where R is a radius vetor from an origin to a point of reflection of a light edge ray from a reflector surface and φ is an angle between the R vector and an exit aperture external point of the concentrator (illuminator) and coordinates (R, φ) represent a point on a reflector curve and α is an angle the light edge ray from an origin point makes with a normal to the reflector curve. The reflector surface allows the light edge ray on the reflector curve to vary as a function of position. In the concentrator an absorber has a shape variable which varies with position along the absorber surface.

Claims

1. A nonimaging concentrator of light, comprising:

a two dimensional reflector shape having a longitudinal axis, said reflector shape defined by solutions for all points along the two dimensional reflector shape of a differential equation of polar coordinates;

##EQU23## where R is a radius rector from an origin to a point of reflection of a light edge ray from the two dimensional reflector shape and φ

is an angle between the R vector and a reference direction and coordinates (R, φ

) represent a point on said reflector shape and α

is an angle the light edge ray from an origin point makes with a normal to said two dimensional reflector shape; and

said two dimensional reflector shape defined by a reflector curve which allows the light edge ray on said two dimensional reflector shape to vary as a function of position, thereby providing a plurality of edge rays for collection by the concentrator.

2. The nonimaging concentrator as defined in claim 1 wherein the concentrator is a compound elliptical concentrator (CEC) wherein α

has the following functional behavior, ##EQU24## where θ

₁, is a maximum angle of light rays striking an entrance aperture of said concentrator and θ

₂ is a maximum angle of the light rays leaving an exit aperture of said concentrator.

3. The nonimaging concentrator as defined in claim 1 wherein a three dimensional shape is selected from the group consisting of the shape formed by rotating the two dimensional reflector shape about the longitudinal axis and translating the two dimensional reflector shape perpendicular to a plane of the shape.

4. The nonimaging concentrator as defined in claim 1 wherein the concentrator is a compound elliptical concentrator (CEC) wherein α

has the following functional behavior;

##EQU25## where θ

₁, is a maximum angle of light rays striking an entrance aperture of said concentrator and θ

₂ is a maximum angle of the light rays leaving an exit aperture of said concentrator.

5. The nonimaging concentrator as defined in claim 1 wherein said concentrator is a compound hyperbolic concentrator (CHC) and solutions to dR/dφ

=R tan α

are determined in two parts over angles φ

, a first part uses an angle θ

₁ defined as the maximum angle of light rays striking an entrance aperture obtained by starting from an origin at an edge of a source distribution, drawing a ray from an opposite source edge through said reflector curve with the ray not passing though the region between entrance edge points A and A'"'"' defining said entrance aperture and in a second part the θ

₁ is defined by a second light ray from the opposite source edge passing between A and A'"'"' and raytracing backwards toward the source until the largest angle is founds and α

is defined by, ##EQU26## .

6. The nonimaging concentrator as defined in claim 5 wherein the solutions to dR/dφ

commence with an outside edge of the reflector curve and continue inwardly.

7. The nonimaging concentrator as defined in claim 1 wherein an absorber is not flat and said α

is defined by, ##EQU27## where θ

₁ is a maximum angle of the light rays striking an entrance aperture of said concentrator and δ

(R,φ

) is an angle the extreme edge ray makes at the point (R,φ

).

8. The nonimaging concentrator as defined in claim 7 wherein the absorber is circular and δ

=arc sin (ρ

/R) where ρ

is a radius of the absorber.

9. The nonimaging concentrator as defined in claim 1 further adding a lens and the light edge ray is defined by a backward raytrace through the lens determining the maximum angle inside a source distribution.

10. The nonimaging concentrator as defined in claim 1 and said reflector shape causing all light rays to satisfy total internal reflection such that α

is defined by, ##EQU28## where θ

₁ is a maximum angle of the light rays striking an entrance aperture of said concentrator and n is an index of refraction of a medium within said concentrator.

11. The nonimaging concentrator as defined in claim 10 wherein the n is a variable value.

12. The nonimaging concentrator as defined in claim 1 further including a nonimaging secondary element for restoring aberrational losses in concentration.

13. The nonimaging concentrator as defied in claim 12 wherein the location and aperture of said nonimaging secondary element is defied by an envelope curve rotated by θ

_track which includes all angular deviations within said concentrator and the envelope is expressed as;

space="preserve" listing-type="equation">X=rsin.sup.3 γ

space="preserve" listing-type="equation">Y=(-3/2)rcosγ

+rcos.sup.2γ

where r is a primary arc radius of a curvature and γ

defines an angular position a ray reflects from said reflector shape and a position on said envelope to which it is tangent.