Optical coherence measurements of vortex light fields using optically manipulated micro-apertures

In this paper, we make use of optically controlled phase sampling methods with the use of a dual beam optical trapping system. The dual beam trap enables us to remotely position a single birefringent particle and a second silica microsphere to form a Young's slits type experiments within a probe laser field. The controlled rotation of the birefringent particle means that it acts as both a micro-diffuser and diffracting aperture at the same time. By observing the visibility of the far-field interference fringes, we measure the relative mutual coherence of the optical field between any two selected point sources. This technique provides us with a unique localized sampling method.