Controlled focus shaping with generalized cylindrical vector beam.

An optical system is proposed for the controlled focus shaping of generalized cylindrical vector beams by a high-numerical-aperture lens. A segmented electro-optical filter with four concentric belts is introduced and works with a double-λ/2-plate. By controlling the rotational angle of the plate and the voltage applied to the filter with proper azimuth angle, a three-dimensional engineered focusing field, such as an electrically controlled axial-shifted focus, extended depth of focus, and a diffraction-limited optical tube, can be achieved. The main advantage of this focusing system is that the focused field can be adjusted and formed by the applied voltage and the rotational angle of the half-wave plates. It can provide a new focus shaping technique with free adjustability and flexibility. [ABSTRACT FROM AUTHOR]