Figure 2
The experimental arrangement for the generation and measurement of a caustic vector vortex optical field. An expanded and collimated laser beam is incident on the Spatial Light Modulator (SLM) with a two-dimensional (2D) holographic grating displayed on the SLM. At the Fourier plane of the 4f system, only two of the first orders, located respectively in the x and y axes, are allowed to pass through two separate open apertures and then converted by two λ/4 plates into the left- and right-hand circularly polarized beams, respectively. A Ronchi phase grating is placed in its rear focal plane by 45° with respect to the x direction to recombine the selected orders. The resulting intensity distribution of the beams is recorded by a charge-coupled device (CCD) camera after passing the x-direction linear polarizer, y-direction linear polarizer, left-hand circular polarizer and right-hand circular polarizer analyzers.
