Tunable edge enhancement by higher-order spiral Fresnel incoherent correlation holography system

Abstract Tunable edge enhancement can selectively emphasize the edge features of objects. We demonstrate a higher-order spiral Fresnel incoherent correlation holography system to realize isotropic edge enhancement with tunable width. The spatial light modulator is space-division multiplexed by a conventional lens and a spiral lens with a series of higher-order Laguerre–Gaussian phases. The effects of the radial quantum number p and the angular quantum number l on the spatial filtering are theoretically discussed, as well as confirmed by simulations and experiments. Reconstruction images of resolution target, hairs and label-free onion cells all show obvious tunable edge enhancement effects, which makes the edge information easier to be identified. Furthermore, double-edge enhancement is also detected for the first time.