2ND-STAGE CONCENTRATORS - A NEW FORMALISM

The concept of second-stage nomimaging concentrators is redefined. A model of an incoherent source of limited emitting angle serves to simulate the input rays to these elements. Hence the second stages may be classified as a subgroup of ideal concentrators that collect all the radiation emitted by such sources and concentrate it up to the maximum achievable limit. As a consequence of this discussion, it becomes obvious that, for any given plane behind a primary, an ideal second stage can be designed with its entrance aperture located on that plane. Implications for the design reflectors with shielding windows are discussed. 18 refs.