Focusing Properties of Spirally Polarized Axisymmetric QBG Beams with 4pi Configuration

4Pi Focusing properties of spirally polarized axisymmetric QBG beams are investigated theoretically by vector diffraction theory. Calculation results show that intensity distribution in focal region can be altered considerably by beam parameter μ and spiral parameter C that indicates polarization spiral degree.By properly tuning the beam parameter and spiral parameter generated multiple focal structure for potential application are also dicussed.The author expect such an investigation is worth will for optical manipulation and material processing technologies.