Curved holographic optical elements for diffuse light collimation and concentration

A new type of optical instrument, the carved hologram, is introduced that allows us the unique opportunity to independently control its spatial phase function and its shape (whereas in reflecting or refracting optical elements the shape uniquely determines the spatial phase function). We show how proper design of the 2D hologram shape for a given light source intensity distribution (using a simple analytic procedure) yields perfect uniform collimation. We then demonstrate how the same hologram shape leads, for the same light source shape now used as a target, to concentration of diffuse (monochromatic) light at the thermodynamic limit of brightness conservation. Specific practical examples of flat and cylindrical Labertian targets are considered. The procedure is then extended for finite source-target distances, possibly applicable for efficient and uniform side-pumping of laser rods. Finally, extension possibilities for 3D geometries are investigated.