Focusing diffractive cylindrical mirrors: rigorous evaluation of various design methods

The performance characteristics of focusing diffractive mirrors designed wi th various methods are evaluated by using the rigorous boundary element met hod. Quantitative results are presented for (1) conventional-zero-thickness mirror designs, (2) alternative-zero-thickness designs that incorporate an off-axis correction factor and (3) finite-thickness designs. For TM polari zation, the mirrors designed by using the alternative-zero-thickness method perform considerably worse than those designed by using the conventional-z ero-thickness method, which contradicts predictions made in an earlier pape r [J. Opt. Sec. Am. A 17, 1132 (2000)]. (C) 2001 Optical Society of America .