Multiple annular linear diffractive axicons

Abstract

We propose a chromatic analysis of multiple annular linear diffractive axicons. Large aperture axicons are optical devices providing achromatic nondiffracting beams, with an extended depth of focus, when illuminated by a white light source, due to chromatic foci superimposition. Annular apertures introduce chromatic foci separation, and because chromatic aberrations result in focal segment axial shifts, polychromatic imaging properties are partially lost. We investigate here various design parameters that can be used to achieve color splitting, filtering, and combining using these properties. In order to improve the low-power efficiency of a single annular axicon, we suggest a spatial multiplexing of concentric annular axicons with different sizes and periods we call multiple annular aperture diffractive axicons (MALDAs). These are chosen to maintain focal depths while enabling color imaging with sufficient diffraction efficiency. Illustrations are given for binary phase diffractive axicons, considering technical aspects such as grating design wavelength and phase dependence due to the grating thickness.

Diffraction of ultrashort optical pulses from circularly symmetric binary phase gratings

“…Binary amplitude diffractive optical elements with circular symmetry under femtosecond pulsed illumination have been theoretically studied in [10,11] and also experimentally in [12]. The chromatic analysis of circularly symmetric binary phase multiple annular linear diffractive axicons has been carried out in [13]. Circularly symmetric binary amplitude diffraction gratings have been studied in [14], where expressions for the total diffraction field in the time and spectral domain are provided using the Rayleigh-Sommerfeld formulation of the diffraction.…”

Characterization of Bessel beams generated by polymeric microaxicons

“…Axicons can be designed refractively [4,7,8] or diffractively [9][10][11][12] and, depending on the applications, with very different sizes: base diameters range from 200 μm [6] up to several centimetres. Microaxicons (diameter of about a mm or less) [13] are used for example at the ends of optical fibres [14,15], for near-field microscopes [16], with pulsed lasers [17], for optical coherence tomography [8], and also for optical manipulation of micrometric (biological) objects [2,3,5,[18][19][20][21][22][23].…”