Non-local edge enhanced imaging with incoherent thermal light

Spiral phase contrast imaging is an effective technique for the edge enhancement of a phase object. The spiral phase filter is the core component of the system and it provides sensitivity to the phase and amplitude gradients of the object. General spiral phase contrast imaging depends on the 4f imaging system in a single light beam with the coherent light source of visible or infrared wavelengths. Here, we constructed a non-local edge enhanced imaging system using an incoherent thermal light source. The detected object and the adopted spiral phase filter were non-locally placed in two separated light beams. The edge enhanced ghost image of the phase object can then be achieved through second-order intensity correlation measurements. The classical nature of the spatial degree of freedom of our proposed edge enhanced ghost imaging system was also demonstrated through the measurement of Bell-type inequality.