title: Long-distance optical guiding of colloidal particles using holographic axilens.
abstract: We report the use of an aspheric holographic optical element (axilens) that essentially combines the properties of the long focal depth of an axicon and the high energy concentration of a conventional spherical lens for long-distance guiding of microscopic objects. With the use of the axilens, polystyrene spheres (~6 μm diameter) could be transported over a distance of ~16 mm that was ~3 times longer compared with that obtained using a spherical lens of focal length identical to the mean focal length of the axilens. Further, due to the availability of good on-axis power density, even objects having very marginally higher refractive index than the medium (differing only at third decimal place) could be guided with a guiding speed of ~5 μm/s.
authors.affiliation: Laser Biomedical Applications and Instrumentation Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India. rsunita@rrcat.gov.in
authors.forename: Sunita
authors.initials: S
authors.lastname: Ahlawat
authors.forename: Ravi Shanker
authors.initials: RS
authors.lastname: Verma
authors.forename: Raktim
authors.initials: R
authors.lastname: Dasgupta
authors.forename: Pradeep Kumar
authors.initials: PK
authors.lastname: Gupta
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004867:Equipment Design; D006696:Holography; D007834:Lasers; D007909:Lenses; D008081:Liposomes; D008853:Microscopy / Q000379:methods; D016011:Normal Distribution; D055095:Optics and Photonics; D011137:Polystyrenes / Q000737:chemistry*; D012031:Refractometry
chemical_list: D003102:Colloids; D008081:Liposomes; D011137:Polystyrenes