Control of luminous intensity distribution from an array of point light sources

Abstract

In various embodiments, a lens array comprises a plurality of aspheric lens elements each optically coupled to a light-emitting element and producing an out-of-focus image thereof. The images combine to generate a target luminous intensity distribution, e.g., providing constant illuminance on a plane.

What is claimed is: 
     
         1 . A luminaire producing light having a substantially quadrilaterally symmetric spatially constant luminous intensity distribution, the luminaire comprising:
 an array of light-emitting elements; and   a lens array comprising a continuous layer of transparent material having a first surface for receiving light from the light-emitting elements and, formed on a second surface thereof opposed to the first surface, a two-dimensional array of aspheric lens elements each (i) having an outer edge having a substantially square shape, (ii) being optically coupled to a closest one of the light-emitting elements, and (iii) producing an out-of-focus image thereof on a planar surface located at a predetermined distance from the lens array, the images combining to generate a substantially quadrilaterally symmetric spatially constant illumination over the planar surface.   
     
     
         2 . The luminaire of  claim 1 , wherein the lens elements each have a lens profile described by the lowest-order mathematical equation that generates a predetermined luminous intensity distribution when light emitted by the light-emitting elements and passing through the lens elements is combined, the profile specifying a lens shape and a lens thickness. 
     
     
         3 . The luminaire of  claim 2 , wherein the equation comprises parameters including a refractive index of the lens and dimensions of the light-emitting element, the thickness corresponding to a distance from a front surface of the lens element to the light-emitting element. 
     
     
         4 . The luminaire of  claim 2 , wherein the equation is a quadratic equation. 
     
     
         5 . The luminaire of  claim 2 , wherein the equation is a cubic equation. 
     
     
         6 . The luminaire of  claim 2 , wherein each lens element is a Fresnel lens. 
     
     
         7 . The luminaire of  claim 2 , wherein each lens element has a hyperbolic lens profile. 
     
     
         8 . The luminaire of  claim 2 , wherein each lens element has a conic linear lens profile. 
     
     
         9 . The luminaire of  claim 2 , wherein each lens element produces a batwing luminous distribution profile. 
     
     
         10 . The luminaire of  claim 2 , wherein each lens element produces a substantially collimated light distribution profile. 
     
     
         11 . The luminaire of  claim 10 , wherein the collimated light distribution profile has a beam angle less than 15°. 
     
     
         12 . The luminaire of  claim 2 , wherein the light distribution of each lens element is asymmetric. 
     
     
         13 . The luminaire of  claim 12 , wherein the asymmetric light distribution is an asymmetric collimated light distribution. 
     
     
         14 . The luminaire of  claim 13 , wherein the asymmetric collimated light distribution has a beam angle less than 15°. 
     
     
         15 . The luminaire of  claim 1 , wherein the light-emitting elements have rectangular emission surfaces. 
     
     
         16 . The luminaire of  claim 1 , wherein the light-emitting elements have square emission surfaces. 
     
     
         17 . The luminaire of  claim 1 , wherein an aspheric profile of each lens element is analytically described by the cubic equation z=c×a 3 +b, where a is the distance from the lens center in a plane perpendicular to the lens axis of rotation, z is the lens thickness at distance a, and b and c are constants. 
     
     
         18 . The luminaire of  claim 17 , wherein c is −0.02, b is 4.0, a is between 0 and 5.0, and z, a, and b are measured in millimeters. 
     
     
         19 . The luminaire of  claim 1 , wherein a center of each light-emitting element is shifted relative to a center of the aspheric lens element to which it is optically coupled. 
     
     
         20 . The luminaire of  claim 1 , wherein a center of each light-emitting element is substantially aligned with a center of the aspheric lens element to which it is optically coupled. 
     
     
         21 . The luminaire of  claim 1 , wherein each of the lens elements is in contact with neighboring lens elements. 
     
     
         22 . The luminaire of  claim 1 , wherein the light-emitting elements are uniformly offset relative to the lens element optical axes. 
     
     
         23 . The luminaire of  claim 1 , wherein each of the light-emitting elements is directly bonded to the first surface of the layer of transparent material. 
     
     
         24 . A method of manufacturing a luminaire for achieving a predetermined luminous intensity distribution, the method comprising:
 designing one or more optical elements to produce an out-of-focus image of a light source by computationally modifying an initial lens profile until a resulting profile is described by the lowest-order mathematical equation that will generate the predetermined light intensity distribution from the light source;   providing a plurality of the light sources arranged in an array;   manufacturing a plurality of the optical elements; and   associating the optical elements with the light sources such that each of the optical elements produces an out-of-focus image of an associated light source, the images combining to generate the predetermined luminous intensity distribution, thereby forming a luminaire comprising:
 an array of light-emitting elements; and 
 a lens array comprising a continuous layer of transparent material having a first surface for receiving light from the light-emitting elements and, formed on a second surface thereof opposed to the first surface, a two-dimensional array of aspheric lens elements each (i) having an outer edge having a substantially square shape, (ii) being optically coupled to a closest one of the light-emitting elements, and (iii) producing an out-of-focus image thereof on a planar surface located at a predetermined distance from the lens array, the images combining to generate a substantially quadrilaterally symmetric spatially constant illumination over the planar surface. 
   
     
     
         25 . The method of  claim 24 , wherein the initial lens profile is spherical. 
     
     
         26 . The method of  claim 24 , wherein at least one optical element is manufactured by molding. 
     
     
         27 . The method of  claim 24 , wherein at least one optical element is manufactured by embossing.