Slide-free histological imaging by microscopy with ultraviolet surface excitation using speckle illumination

Microscopy with ultraviolet surface excitation (MUSE) is a promising slide-free imaging technique to improve the time-consuming histopathology workflow. However, since the penetration depth of the excitation light is tissue dependent, the image contrast could be significantly degraded when the depth of field of the imaging system is shallower than the penetration depth. High-resolution cellular imaging normally comes with a shallow depth of field, which also restricts the tolerance of surface roughness in biological specimens. Here we propose the incorporation of MUSE with speckle illumination (termed MUSES), which can achieve sharp imaging on thick and rough specimens. Our experimental results demonstrate the potential of MUSES in providing histological images with ∼ 1 μm spatial resolution and improved contrast, within 10 minutes for a field of view of 1.7 mm × 1.2 mm . With the extended depth of field feature, MUSES also relieves the constraint of tissue flatness. Furthermore, with a color transformation assisted by deep learning, a virtually stained histological image can be generated without manual tuning, improving the applicability of MUSES in clinical settings.