UNIFORMIZATION OF THE AXIAL INTENSITY OF DIFFRACTION AXICONS BY POLYCHROMATIC ILLUMINATION

The axial intensity of axicons illuminated by a coherent wave usually exhibits rapid oscillations from diffraction on the sharp edges of the aperture of the element. These oscillations can be suppressed when th e diffractive version of the axicon is illuminated from a polychromati c source. This possibility is examined based on the example of the ann ular-aperture logarithmic axicon. The estimate for the wavelength inte rval of the illuminating source required for uniformization is obtaine d with the help of Furthermore the shape of the radial intensity distr ibution can be These findings are con firmed by numerical evaluation o f the Fresnel the stationary-phase method. maintained almost unchanged . diffraction integral. (C) 1996 Optical Society of America