The concept of second-stage nonimaging 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 of ideal reflectors with shielding windows are discussed.
© 1983 Optical Society of America
Eli M. Kritchman, "Second-stage concentrators—a new formalism," J. Opt. Soc. Am. 73, 508-511 (1983)