The Use of a Kaleidoscope to Obtain Uniform Flux Over a Large Area in a Solar or Arc Imaging Furnace

The use of properly designed light pipes to redistribute the energy of a solar furnace or an arc imaging furnace is discussed. Compared to alternate schemes of obtaining uniform irradiation over a large area, the light pipe has the advantage of good uniformity without a serious loss of efficiency. Theoretical analyses concerning the principle of operation, as well as formulas for estimating the flux uniformity and reflection losses, are discussed. The results also indicate that the only suitable cross sections are the square, triangular, hexagonal, and rectangular. Other cross sections, including the circular, are not satisfactory unless used with diffusely reflecting surfaces.