title: Fabrication of binary Fresnel lenses in PMMA by femtosecond laser surface ablation.
abstract: We report on the fabrication of binary Fresnel lenses by femtosecond laser surface ablation of poly(methyl methacrylate) (PMMA) substrates. Tight focusing of the laser pulses produced a minimum ablated feature size of 600 nm, enabling the creation of lenses with numerical apertures as high as 0.5 and focal lengths ranging from 500 µm to 5 mm. A precise control of the ablation depth allowed the achievement of a 30% focusing efficiency, close to the maximum theoretical value for this kind of lenses.
authors.affiliation: Istituto di Fotonica e Nanotecnologie-CNR, Dipartimento di Fisica-Politecnico di Milano, Milano, Italy. rebeca.martinezvazquez@ifn.cnr.it
authors.forename: Rebeca Martínez
authors.initials: RM
authors.lastname: Vázquez
authors.forename: Shane M
authors.initials: SM
authors.lastname: Eaton
authors.forename: Roberta
authors.initials: R
authors.lastname: Ramponi
authors.forename: Giulio
authors.initials: G
authors.lastname: Cerullo
authors.forename: Roberto
authors.initials: R
authors.lastname: Osellame