[OPTICAL REVIEW Vol. 7, No. 3 (2000) 266-274]

Imaging Properties of Hard X-Ray Zone Plates with Corrugated Boundary Roughness

Kazutoshi NAKAJIMA

Osaka National Research Institute, AIST, 1-8-31 Midorigaoka, Ikeda, Osaka, 563-8577 Japan

(Received October 8, 1999; Accepted February 17, 2000)

The imaging properties of hard X-ray multilayer zone plates with corrugated roughness along circular zone boundaries are investigated. First, the transmission function for zone plates with the roughness is derived using a geometric optical approach, and based on the Fresnel-Kirchhoff diffraction theory formulas are developed to calculate the point spread function (PSF) efficiently, assuming that the roughness increases with radius. Then, the PSFs for various magnitudes and angular configurations of the roughness are presented, and the imaging properties are discussed particularly in terms of the focusing efficiency (or the Strehl ratio) and the resolution. Tolerances for the maximum magnitude of the roughness, and the relationship between the angular configuration of the roughness and the symmetry of the PSF are also discussed.

Key words : X-ray zone plate, multilayer zone plate, X-ray focusing optics, boundary roughness, diffraction, image formation, imaging properties