Image edge enhancement in optical microscopy with a Bessel-like amplitude modulated spiral phase filter

We experimentally demonstrate that a Bessel-like amplitude modulated spiral phase filter can be used in a real-time spatial image edge enhancement system in optical microscopy for biological sample imaging. Compared with previous methods based on a conventional spiral phase filter, a dark-field spiral phase filter and the Laguerre–Gaussian modulated spiral phase filter, the proposed technique further reduces the imaging diffraction noise. Experimental verifications in edge enhancement are implemented by a phase-only spatial light modulator for realizing the amplitude modulated spiral phase. It is shown that the proposed technique is able to efficiently suppress the diffraction noise and achieve high quality edge enhancement images for biological samples.