Label-free surface sectioning deep ultraviolet tissue imaging in multimodalities.

Histology is essential for accurate and effective diagnosis of many diseases and cancers. However, the slicing and staining processes are often expensive, complex, and sometimes invasive to biomedical samples. deep ultraviolet (DUV) microscopy has recently emerged as a promising label-free imaging technique due to the strong absorption of nucleic acids at DUV wavelengths. Here, we present a DUV confocal microscope for label- and slide-free, high-resolution tissue imaging. Compared to visible light, DUV illumination offers thinner optical sectioning and improved contrast due to its shallow penetration depth. We demonstrate that larger pinhole sizes can be used without loss of image quality, enhancing system efficiency. In addition to the DUV confocal microscopy, we explored transmission, epi-illumination, and oblique illumination modes for cost-effective DUV imaging platforms. To evaluate their performance, we conducted side-by-side comparisons using a range of samples, including paraffin-embedded and fresh mouse tissues, as well as health and cancerous human tongue specimens. Among these, oblique illumination demonstrates the best performance for imaging fresh tissues, minimizing background signals while revealing detailed cellular structures. Our findings provide a comprehensive analysis and strongly support the potential of DUV microscopy as a promising tool for rapid, stain-free, and slide-free histopathology. This approach could significantly streamline diagnostic workflows by reducing preparation time and costs.