Kotlyar Victor V, Kovalev Alexey A, Khonina Svetlana N, Skidanov Roman V, Soifer Victor A, Elfstrom Henna, Tossavainen Noora, Turunen Jari
Image Processing Systems Institute, Russian Academy of Sciences, Samara State Aerospace University.
Appl Opt. 2006 Apr 20;45(12):2656-65. doi: 10.1364/ao.45.002656.
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.
