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Proceedings ArticleDOI

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

15 Mar 2016-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 9753, pp 233-238

AbstractA 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.

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References
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Journal ArticleDOI
TL;DR: A novel aspheric holographic optical element, the holographic axilens, is reported for achieving extended focal depth while keeping high lateral resolution.
Abstract: We report a novel aspheric holographic optical element, the holographic axilens, for achieving extended focal depth while keeping high lateral resolution. The element is designed according to special optimization techniques and recorded as a computer-generated hologram. The results for a specific element, which has a depth of focus of 30 mm, a lateral resolution of 80 microm, a focal length of 1250 mm, and a diameter of 12.5 mm at a wavelength of 633 nm, are presented.

208 citations

Journal ArticleDOI
TL;DR: The purpose of this paper is to show that when a lens-axicon combination is illuminated by a Gaussian beam, the transverse distribution of the focal ring is also aGaussian distribution.
Abstract: An axicon and a lens are combined to form an optical system producing a ring-shaped pattern. The purpose of this paper is to show that when a lens-axicon combination is illuminated by a Gaussian beam, the transverse distribution of the focal ring is also a Gaussian distribution. The typical width of this distribution was found to be, in the case of the lens-axicon combination, 1.65 times greater than the typical width of the Gaussian beam obtained by focusing the same beam using the lens alone. This focusing system is well suited for the drilling of good quality large diameter holes using a high power laser beam.

135 citations


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MonographDOI
27 Oct 2009

74 citations

Journal ArticleDOI
TL;DR: Noncontact cornea trephination was performed on human eye-bank eyes by using a Q-switched Er:YAG laser with a axicon-lens combination to demonstrate the possibility of replacing mechanical trephinations in corneal surgery.
Abstract: A new laser beam delivery system using axicon beam shaping has been designed to produce controllable surface ablation as well as trephination for the corneal surgery. Noncontact cornea trephination was performed on human eye-bank eyes by using a Q-switched Er:YAG laser with a axicon-lens combination. The results shows that the uniformity of the trephination along the ring depends on the radial symmetry of the beam. The histological results of the samples show that the damage zone of the laser cut is less than 10 mu m. This demonstrates the possibility of replacing mechanical trephination in corneal surgery. >

61 citations

Journal ArticleDOI
Abstract: (Received 26 October 2011; revised manuscript received 24 January 2012; published 27 March 2012) Microparticle self assembly under the influence of optical forces produced by higher-order optical beams or by projection of a hologram into the trapping volume is well known. In this paper, we report the spontaneous formation of a ring of identical microspheres (each with diameter 1.1 μm) in conventional single-beam optical tweezers with a usual TEM00 Gaussian beam coupled into a sample chamber having a standing wave geometry with a cover slip and glass slide. The effects of different experimental parameters on the ring formation are studied extensively. The experimental observations are backed by theoretical simulations based on a plane wave decomposition of the forward- and backward-propagating Gaussian beams. The ring patterns are shown to be caused due to geometrical aberrations produced by focusing the Gaussian beam using a high-numerical-aperture microscope objective into stratified media. It is found that the thickness of the stratified media and the standing wave geometry itself play a critical role in the formation of stable ring structures. These structures could be used in the study of optical binding, as well as of biological interactions between cells in an optical trap.

19 citations