Lens axicon illuminated by polychromatic Gaussian beams for generating uniform focal segments

In this paper, we investigate a lens axicon, which actually is a lens with spherical aberration, illuminated by a polychromatic Gaussian beam for producing an extended axial line image of a desired length and nearly uniform intensity. A numerical calculation is performed to investigate the dependence of the axial intensity distribution of the focal segment on the parameters of the incident polychromatic Gaussian beam. It is shown that, compared with monochromatic Gaussian beam illumination, the illumination of the polychromatic Gaussian beam may improve the uniformity of the distribution of the axial intensity, and this improvement in the uniformity of the axis intensity is strongly dependent on the spectral width of the incident Gaussian beam. Moreover, apodization with annular super-Gaussian amplitude distribution is employed to reduce the undesired oscillation of the axial intensity.