Diffractive X-Ray Telescopes

Table 2

The primary focus efficiency, in the absence of absorption, of a stepped approximation to a PFL (see [34]).

Levels	2 (PZP)	3	4	8	16	𝑛
Efficiency	40.5%	68.4%	81.1%	95.0%	98.7%	sinc^2(𝜋/𝑛)