Axicons in oblique illumination produce broadened focal lines, a problem, e.g., in scanning applications. A compact mathematical description of the focal segment is presented, for the first time, to our knowledge, and the results are compared with elliptical axicons in normal illumination. In both cases, analytical expressions in the form of asteroid curves are obtained from asymptotic wave theory and caustic surfaces. The results are confirmed by direct diffraction simulations and by experiments. In addition we show that at a fixed angle an elliptical axicon can be used to compensate for the adverse effects of oblique illumination.
© 2003 Optical Society of America
[Optical Society of America ]
(050.1960) Diffraction and gratings : Diffraction theory
(050.1970) Diffraction and gratings : Diffractive optics
(230.3990) Optical devices : Micro-optical devices
(260.1960) Physical optics : Diffraction theory
Anna Thaning, Zbigniew Jaroszewicz, and Ari T. Friberg, "Diffractive Axicons in Oblique Illumination: Analysis and Experiments and Comparison with Elliptical Axicons," Appl. Opt. 42, 9-17 (2003)