Based on the vectorial Debye theory, the tight focusing properties of partially coherent, radially polarized vortex beams are investigated in detail. In this paper, we propose to use an amplitude modulated filter in combination with a high NA lens to generate long focal depth in the focal region. Numerical results show that the generation of long focal depth of FWHM (22.08λ) is achieved, which finds useful application in microscopy techniques such as particle acceleration, laser processing, optical micromanipulation, and beam shaping.
For partially coherent hollow Gaussian beam (HGB), the turbulent distance, in which all of the spatial and angular spreading and the beam propagation factor increasing due to turbulence can be neglected, has been investigated in detail. It is shown that the turbulent distance of partial coherent HGBs increases with increasing beam order and wavelength, and decreasing turbulent parameter and coherent parameter. With increasing waist width, the turbulent distance first increases and then decreases. Furthermore, the turbulent distance of a HGB is much larger than that of the corresponding Gaussian Schell-model (GSM) beam when choosing the appropriate value of the waist width, implying that a HGB may be more appropriate to be used in optical communication links than a GSM beam.
Partially Coherent, Radially Polarized Beam with Annular Apodization