LED light source with field-of-view-controlling optics

An apparatus comprising a light source which emits light for viewing at various angles, said light source comprising:

• an LED having a front surface, a back surface opposite said front surface, and four side surfaces, wherein said front surface and said four side surfaces emit light and wherein said front surface and said four side surfaces intersect along four upper edges, respectively;
• and
• a Lambertianizing cup comprising a bottom surface and four reflector surfaces, one facing each of said four side surfaces of said light-emitting diode, at least one opposed pair of said reflector surfaces configured to provide a substantially cosine fall-off of light intensity as the viewing angle deviates from a viewing direction extending from the light source in a plane perpendicular to said side surfaces of said LED that said pair of reflector surfaces face;
• wherein said reflector surfaces substantially coincide with a locus of points intersecting an arc that is translated along a line parallel to said upper edge of each of said four sides of said LED.

A nonimaging optical element comprising:

• first and second reflectors positioned in spaced, facing relationship, each reflector comprising:
• a middle section comprising a surface in the form of a parabolic cylinder which has a line focus;
• and
• two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,
• wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions.

Beam-shaping optics for shaping a beam emitted from a light-emitting diode, said optics comprising:

• (a) a first set of reflectors positioned adjacent to sides of said light-emitting diode;
• (b) a second set of reflectors oriented to limit beam divergence of light from said light-emitting diode to a limited range of angles in one plane, the second set of reflectors comprising:
• first and second reflectors positioned in spaced, facing relationship, each reflector comprising:
• a middle section comprising a surface in the form of a parabolic cylinder which has a line focus;
• and
• two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,
• wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions;
• and
• (c) an optical element comprised of transmitting material positioned to receive light from said light-emitting diode and said first and second sets of reflectors, wherein said sets of reflectors and transmitting material are oriented and configured to provide a substantially Lambertian fall-off for light intensity in said one plane within said limited range of angles and a substantially Lambertian fall-off for light intensity in an orthogonal plane within a range of angles greater than said limited range of angles.

A method of manipulating light emitted from a light-emitting diode to provide a light source that substantially obeys Lambert's cosine-law through a range of viewing angles, said method comprising the steps of:

• collecting light emitted from plural side surfaces of a light-emitting diode and redirecting said light so that the light emitted by the light source approximates light emitted by a single Lambertian surface;
• reducing the divergence of collected light in a plane orthogonal to an opposing pair of said plural sides by guiding the collected light through first and second reflectors positioned in spaced, facing relationship, each reflector comprising:
• a middle section comprising a surface in the form of a parabolic cylinder which has a line focus;
• and
• two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,
• wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions;
• and
• refracting collected light after reducing the divergence.

A method of shaping the output of a light-emitting diode having a front and a plurality of sides that emit light, said method comprising the steps of:

• collecting light emitted from said sides and redirecting said light to simulate light produced by a single substantially Lambertian surface;
• using reflectors to reduce the divergence of the beam in one direction to a limited range of angles while maintaining a substantially Lambertian fall-off within a substantial portion of said limited range, wherein the reflectors comprise first and second reflectors positioned in spaced, facing relationship, each reflector comprising:
• a middle section comprising a surface in the form of a parabolic cylinder which has a line focus;
• and
• two end sections on opposite sides of said middle section, each end section comprising a surface that joins the surface of the middle section along a parabolic line, said surface of each end section in the form of a paraboloid with a point focus, the point focus of each end section proximate a respective end of said line focus of said middle section,
• wherein the middle sections of the first and second reflectors form a compound parabolic concentrator trough, which together with the end sections of the reflectors provide beam-shaping optics for restricting beam divergence in one of two orthogonal directions.