Optical Spatial Differential Incoherent Microscopy

Abstract Optical spatial differential microscopy is an effective tool for non‐toxicity and label‐free imaging of biological samples. Existing methods mainly focus on coherent light illumination, which inevitably influences imaging quality by laser scattering effects. In this paper, a compact and broadband optical spatial differential microscopy under incoherent illumination is proposed by only inserting a pair of polarizers into a conventional microscopy. The 2D differentiation operation is performed with the polarizers extracting the cross‐polarization term from transmitted light field. Moreover, the effects of light source coherence and wavelength on spatial differentiation are discussed in detail. The results show that this scheme can realize high‐quality spatial differentiation imaging for the biological cells, transparent plastic scratches, and real‐time monitoring of bubbles. It is experimentally demonstrated that the system can still perform stably when the incident angle exists a large misalignment with a single short‐focus lens imaging. This method may further reduce the size of the differential system and drive the advancement of optical microscopy with incoherent light.