title: Diffraction of conic and Gaussian beams by a spiral phase plate.
abstract: An analytical expression for the spatial spectrum of the conic wave diffracted by a spiral phase plate (SPP) with arbitrary integer singularity of order n is obtained. Conic wave diffraction by the SPP is equivalent to plane-wave diffraction by a helical axicon. A comparison of the conic wave and Gaussian beam diffraction on a SPP is made. It is shown that in both cases a light ring is formed, with the intensity function growing in proportion to rho(2n) at small values of radial variable rho and decreasing as n(2)rho(-4) at large rho. By use of direct e-beam writing on the resist, a 32 level SPP of the 2nd order and diameter 5 mm is manufactured. By use of this SPP, a He-Ne laser beam is transformed into a beam with phase singularity and ringlike intensity distribution. A four-order binary diffractive optical element (DOE) with its transmittance proportional to a linear superposition of four angular harmonics is also manufactured. With this DOE, simultaneous optical trapping of several polystyrene beads of diameter 5 microm is performed.
authors.affiliation: Image Processing Systems Institute, Russian Academy of Sciences, Samara State Aerospace University.
authors.forename: Victor V
authors.initials: VV
authors.lastname: Kotlyar
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Kovalev
authors.forename: Svetlana N
authors.initials: SN
authors.lastname: Khonina
authors.forename: Roman V
authors.initials: RV
authors.lastname: Skidanov
authors.forename: Victor A
authors.initials: VA
authors.lastname: Soifer
authors.forename: Henna
authors.initials: H
authors.lastname: Elfstrom
authors.forename: Noora
authors.initials: N
authors.lastname: Tossavainen
authors.forename: Jari
authors.initials: J
authors.lastname: Turunen