Compact optics by multichanneling the ray bundles
Compacting devices is an increasingly demanding requirement for many applications in nonimaging and imaging optics. “Compacting” means here decreasing the volume of the space between the entry and the exit aperture without decreasing the optical performance. After reviewing the different techniques to do so, we analyze here the multichannel strategies in both fields: imaging and non-imaging. These type of designs split the incoming bundle of rays in different sub-bundles that are optically processed (independently) and then recombined in a single outgoing bundle. Because the etendue of each sub-bundle is smaller than that of the full bundle, the volume of the optics rapidly decreases as the number of sub-bundles increases. These designs usually need to be combined with freeform optics for optimum performance.