Quantitative comparison of different mounting media for transmissive DUV imaging of label-free biological specimens.

Deep ultraviolet has emerged as a robust imaging method for label-free histopathology and cytology. This study quantitatively evaluates various mounting media to optimize transmissive DUV imaging. We identified glycerol as the optimal candidate, achieving an internal transmittance of 99.15% at 265 nm and providing a refractive index (n ≈ 1.53) that matches biological specimens and fused silica substrates. While alcohol offers high transparency, its volatility prevents extended imaging; conversely, traditional xylene-based media exhibit near total DUV extinction. Quantitative validation using local entropy, Tenengrad sharpness, and speckle contrast confirms that glycerol suppresses interfacial scattering and improves nuclear visualization across cervical cells and various murine and human tissues. These results establish glycerol as a robust, high-performance medium for enhancing diagnostic fidelity in label-free deep ultraviolet microscopy.