Generation of arbitrary spatially variant polarization beams with a trapezoid Sagnac interferometer.

We present a flexible approach to generate arbitrary vector beams with a trapezoid Sagnac interferometer. With the interferometer, the different orders of two orthogonally polarized beams from computer-generated holograms coincide with each other in Fourier spectrum domain, and coaxially combine into the vector beams. This approach provides convenient way to experimentally study the properties of vector beams with complex polarization.