Light rod for accelerating algae growth

Abstract

A light pipe for use in aqueous environments comprising an optical rod capable of total internal reflection, and disposed in the optical path of a light source such as a light emitting diode or other source. The optical rod has frosted and unfrosted portions, such that the light is propagated distally along the rod at the unfrosted portions, but a portion of the light is coupled out of the rod into the aqueous environment at each of the frosted portions. The relative sizes of the frosted portions are arranged so that substantially the same light power is coupled out of the rod at each frosted section, thus facilitating rapid and uniform growth of algae in the aqueous environment.

What is claimed is: 
     
         1 . A light pipe comprising:
 a rod disposed to receive at a proximal end of the rod light from a light source during use, wherein the rod comprises:
 a transverse cross-section that permits total internal reflection within the rod at a wavelength of the light; and 
 a plurality of separated frosted portions disposed along a longitudinal length of the rod, each of the frosted portions defined by a surface texture on at least a portion of a circumference of the rod that frustrates the total internal reflection; 
   wherein the light propagates along the longitudinal length of the rod, and a portion of the light is coupled out of the rod at the frosted portions during use; and   wherein the frosted portions are disposed at pre-selected positions along the longitudinal length of the rod selected to facilitate growth of a plant when disposed in proximity to the plant during use.   
     
     
         2 . The light pipe of  claim 1  further comprising a homogenizer disposed between the light source and the proximal end of the rod. 
     
     
         3 . The light pipe of  claim 1  wherein the light source is an LED. 
     
     
         4 . The light pipe of  claim 1  wherein the light source is a laser. 
     
     
         5 . The light pipe of  claim 1  wherein the cross section is circular. 
     
     
         6 . The light pipe of  claim 1  wherein the cross-section is non circular. 
     
     
         7 . The light pipe of  claim 1  and further comprising a light source which emits a pre-selected wavelength of light for a pre-selected type of plant. 
     
     
         8 . The light pipe of  claim 1  wherein each of the frosted portions is defined by a surface texture on the circumference of the rod. 
     
     
         9 . The light pipe of  claim 1  wherein the plurality of separated frosted portions have unequal lengths along the longitudinal length of the rod, increasing in length from a shortest proximate the proximal end of the rod to a longest proximate a distal end of the rod. 
     
     
         10 . The light pipe of  claim 9  wherein the plurality of separated frosted portions are comprised by substantially equal-length segments of the rod, each segment of the rod comprising a single frosted portion and a single unfrosted portion. 
     
     
         11 . The light pipe of  claim 9  wherein the plurality of separated frosted portions are comprised by different-length segments of the rod, each segment of the rod comprising a single frosted portion and a single unfrosted portion. 
     
     
         12 . The light pipe of  claim 8  wherein a distal end of the rod opposite a proximal end is rounded. 
     
     
         13 . The light pipe of  claim 1  wherein a distal end of the rod opposite a proximal end is frosted. 
     
     
         14 . The light pipe of  claim 1  wherein a distal end of the rod opposite a proximal end is reflective. 
     
     
         15 . The light pipe of  claim 1  wherein the transverse cross-section is substantially uniform along the longitudinal length of the rod. 
     
     
         16 . The light pipe of  claim 1  wherein the transverse cross-section decreases monotonically in area along the longitudinal length of the rod. 
     
     
         17 . The light pipe of  claim 1  wherein the rod is substantially straight. 
     
     
         18 . The light pipe of  claim 1  wherein the rod is curved. 
     
     
         19 . The light pipe of  claim 1  wherein a first of the plurality of frosted sections has different optical properties than a second of the plurality of frosted sections. 
     
     
         20 . The light pipe of  claim 1  wherein the light pipe is disposed alongside a plant in a plant growth enclosure.