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Proceedings Paper

Composite axilens-axicon diffractive optical elements for generation of ring patterns with high focal depth
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Paper Abstract

A binary Fresnel Zone Axilens (FZA) is designed for the infinite conjugate mode and the phase profile of a refractive axicon is combined with it to generate a composite Diffractive Optical Element (DOE). The FZA designed for two focal lengths generates a line focus along the propagation direction extending between the two focal planes. The ring pattern generated by the axicon is focused through this distance and the radius of the ring depends on the propagation distance. Hence, the radius of the focused ring pattern can be tuned, during the design process, within the two focal planes. The integration of the two functions was carried out by shifting the location of zones of FZA with respect to the phase profile of the refractive axicon resulting in a binary composite DOE. The FZAs and axicons were designed for different focal depth values and base angles respectively, in order to achieve different ring radii within the focal depth of each element. The elements were simulated using scalar diffraction formula and their focusing characteristics were analyzed. The DOEs were fabricated using electron beam direct writing and evaluated using a fiber coupled diode laser. The tunable ring patterns generated by the DOEs have prospective applications in microdrilling as well as microfabrication of circular diffractive and refractive optical elements.

Paper Details

Date Published: 15 March 2016
PDF: 6 pages
Proc. SPIE 9753, Optical Interconnects XVI, 97531D (15 March 2016); doi: 10.1117/12.2213037
Show Author Affiliations
Raghu Dharmavarapu, Indian Institute of Technology Madras (India)
A. Vijayakumar, Indian Institute of Technology Madras (India)
R. Brunner, Ernst-Abbe-Hochschule Jena (Germany)
Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)
Shanti Bhattacharya, Indian Institute of Technology Madras (India)

Published in SPIE Proceedings Vol. 9753:
Optical Interconnects XVI
Henning Schröder; Ray T. Chen, Editor(s)

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