Method and apparatus for concentrating light

Abstract

An apparatus for obtaining radiant energy has first and second photovoltaic receivers. A primary curved reflective surface is disposed to reflect incident polychromatic radiation toward a first focal plane. A spectral separator is disposed between the first focal plane and the primary curved reflective surface. The spectral separator has a dichroic separating surface, convex with respect to the incident reflected polychromatic radiation and treated to reflect a first spectral band toward the first photovoltaic receiver and to transmit reflected polychromatic radiation outside the first spectral band. The spectral separator also has a curved separator reflective surface, convex with respect to the light transmitted through the dichroic separating surface and treated to reflect at least a portion of the light transmitted through the dichroic separating surface toward the second photovoltaic receiver.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a conventional dual-mirror photovoltaic module according to the cassegrain model.

FIG. 2 is a schematic block diagram showing the basic arrangement of an apparatus for obtaining radiant energy according to the present invention.

FIG. 3 is a schematic block diagram showing an apparatus using a prism for light dispersion in one embodiment.

FIG. 4 is a partial perspective diagram of an apparatus for concentrating radiant energy using a prism array for spectral dispersion.

FIG. 5 is a cross-sectional diagram of an apparatus for concentrating radiant energy using a refractive body formed and oriented to provide spectral dispersion.

FIG. 6 is a perspective view of an array of light concentrators.

FIGS. 7A and 7B are perspective views, from input face and rear side respectively, of the structure of a light concentrator.

FIG. 8 is a cross-sectional diagram of an apparatus for concentrating radiant energy using a dichroic spectral separator.

FIG. 9 is a cross-sectional diagram of an apparatus for concentrating radiant energy using a dichroic spectral separator in an alternate embodiment.

FIGS. 10A and 10B are cross-sectional diagrams showing the behavior of a spectral separator for directing light to each of two photovoltaic receivers.

FIGS. 11A and 11B are cross-sectional diagrams showing the behavior and composition of a spectral separator as used in the embodiments of FIGS. 8 and 9.

FIGS. 12A and 12B are top and side views, respectively, of the light concentrator of the present invention in a toric embodiment.

FIGS. 13A, 13B, and 13C are perspective views showing light-handling behavior of the light concentrator of the present invention in a cylindrical embodiment, for incident light at different angles.

FIG. 14 is a cross-sectional diagram showing light handling with improper orientation of the light concentrator.

FIG. 15 is a cross-sectional side view showing stray light traveling within an array of light concentrators.

FIG. 16 is a schematic diagram in perspective, showing a solar energy apparatus with tracking to adapt to the changing position of the radiation source.

Claims

1. An apparatus for obtaining radiant energy comprising: a) first and second photovoltaic receivers;b) a primary curved reflective surface disposed to reflect incident polychromatic radiation toward a first focal plane; andc) a spectral separator disposed between the first focal plane and the primary curved reflective surface, the spectral separator comprising: (i) a dichroic separating surface, convex with respect to the incident reflected polychromatic radiation and treated to reflect a first spectral band toward the first photovoltaic receiver and to transmit reflected polychromatic radiation outside the first spectral band;(ii) a curved separator reflective surface, convex with respect to the light transmitted through the dichroic separating surface and treated to reflect at least a portion of the light transmitted through the dichroic separating surface toward the second photovoltaic receiver.

2. The apparatus of claim 1 wherein the dichroic separating surface is optically decentered with respect to the curved separator reflective surface.

3. The apparatus of claim 1 wherein the curved separator reflective surface is further treated to transmit light in a second spectral band.

4. The apparatus of claim 3 further comprising a third photovoltaic receiver disposed near the first focal plane for receiving light in the second spectral band.

5. The apparatus of claim 3 wherein the second spectral band includes infrared wavelengths.

6. The apparatus of claim 1 wherein the primary curved reflective surface has a dichroic coating.

7. An apparatus for obtaining radiant energy comprising at least two radiation concentrators, wherein each radiation concentrator is extended along its respective cylindrical axis and comprises: a) a three-dimensional body of a substantially transparent material having an input face for accepting an incident polychromatic radiation;b) a primary curved reflective surface disposed to reflect the polychromatic radiation toward a first focal plane; andc) a spectral separator disposed between the first focal plane and the primary curved reflective surface, the spectral separator comprising: (i) a dichroic separating surface, convex with respect to the incident reflected polychromatic radiation and treated to reflect a first spectral band toward a first photovoltaic receiver and to transmit reflected polychromatic radiation outside the first spectral band;(ii) a curved separator reflective surface, convex with respect to the light transmitted through the dichroic separating surface and treated to reflect at least a portion of the light transmitted through the dichroic separating surface toward a second photovoltaic receiver.

8. An apparatus for obtaining radiant energy comprising: a) a three-dimensional body of a substantially transparent material having an input face for accepting an incident polychromatic radiation;b) a primary curved reflective surface disposed to reflect the polychromatic radiation toward a first focal plane;c) a first photovoltaic receiver disposed near the first focal plane; andd) a spectral separator disposed between the first photovoltaic receiver and the primary curved reflective surface, the spectral separator comprising: (i) a second curved reflective surface, convex with respect to the incident reflected polychromatic radiation and treated to reflect a first spectral band toward a second photovoltaic receiver and to transmit reflected polychromatic radiation outside the first spectral band;(ii) a third curved reflective surface, convex with respect to the incident reflected polychromatic radiation and treated to reflect a second spectral band toward a third photovoltaic receiver and to transmit reflected polychromatic radiation outside the second spectral band;wherein the first photovoltaic receiver receives polychromatic radiation transmitted through the second and third curved reflective surfaces.

9. The apparatus of claim 8 wherein the second curved reflective surface is optically decentered with respect to the third curved reflective surface.

10. An apparatus for obtaining radiant energy comprising: a) a dispersion element for conditioning incident polychromatic radiation to obtain a dispersed polychromatic radiation;b) a primary curved reflective surface disposed to reflect the dispersed polychromatic radiation toward a first focal plane;c) a secondary curved reflective surface disposed before the first focal plane and convex with respect to the incident reflected dispersed polychromatic radiation, wherein the secondary curved reflective surface is treated to reflect at least a portion of the dispersed polychromatic radiation toward a second focal plane;d) a first photovoltaic receiver disposed near the second focal plane for receiving a first spectral band of the dispersed polychromatic radiation reflected from the secondary curved reflective surface;ande) a second photovoltaic receiver disposed near the second focal plane for receiving a second spectral band of the dispersed polychromatic radiation reflected from the secondary curved reflective surface.

11. The apparatus of claim 10 wherein the secondary curved reflective surface is treated to transmit a third spectral band and to reflect other light outside the third spectral band and wherein there is a third photovoltaic receiver disposed near the first focal plane for receiving the third spectral band.

12. The apparatus of claim 10 further comprising a body of a dielectric material disposed between the primary and secondary curved reflective surfaces.

13. The apparatus of claim 10 wherein the primary curved reflective surface has an optical power in a first axis that is different from its optical power in a second axis that is orthogonal to the first axis.

14. The apparatus of claim 10 wherein the dispersion element is a prism.

15. The apparatus of claim 10 wherein the dispersion element is a prism array.

16. The apparatus of claim 10 wherein the primary curved reflective surface is substantially parabolic.

17. The apparatus of claim 10 wherein the secondary curved reflective surface is substantially hyperbolic.

18. The apparatus of claim 10 wherein the primary curved reflective surface has a dichroic coating.

19. An apparatus for obtaining radiant energy comprising: a) a dispersion element for conditioning incident polychromatic radiation to obtain a dispersed polychromatic radiation;b) a primary curved reflective surface disposed to reflect the dispersed polychromatic radiation toward a first focal plane;c) a secondary curved reflective surface disposed before the first focal plane and convex with respect to the incident reflected dispersed polychromatic radiation, wherein the secondary curved reflective surface is treated to transmit a first spectral band and to reflect dispersed polychromatic radiation outside the first spectral band toward a second focal plane;d) a first photovoltaic receiver disposed near the first focal plane for receiving the first spectral band;e) a second photovoltaic receiver disposed near the second focal plane for receiving a second spectral band of the dispersed polychromatic radiation reflected from the secondary curved reflective surface;andf) a third photovoltaic receiver disposed near the second focal plane for receiving a third spectral band of the dispersed polychromatic radiation reflected from the secondary curved reflective surface.