2007/01/18 by Walter D. Furlan, Furlan, Walter D., Genaro Saavedra +3
Computer Science · Engineering · Physics and Astronomy · #Digital Holography and Microscopy #Image Processing Techniques and Applications #Optical measurement and interference techniques #physics.optics
paper · pdf · doi:10.48550/arxiv.physics/0701211
7 pages, 4 figures
arxiv created 2007/01/18 · arxiv updated 2009/12/01
Fresnel zone plates are diffractive elements that are essential to form images in many scientific and technological areas, especially where refractive optics is not available. One of the main shortcomings of Fresnel zone plates, which limit their utility with broadband sources, is their high chromatic aberration. Recently presented, Fractal Zone Plates (FZPs) are diffractive lenses characterized by an extended focal depth with a fractal structure. This behaviour predicts an improved performance of FZPs as image forming devices with an extended depth of field and a reduced chromatic aberration. Here we report the achievement of the first polychromatic images obtained with a FZP that confirm these predictions. We show that the polychromatic modulation transfer function (MTF) of a FZP affected by defocus is about two times better than one corresponding to a Fresnel zone plate. This result opens the possibility to improve imaging techniques that use conventional Fresnel zone plates over a wide range of the electromagnetic spectrum, ranging from x-rays to THz.