Shortwave-Infrared Line-Scan Confocal Microscope for Deep Tissue Imaging in Intact Organs

Imaging at wavelengths beyond the visible spectrum enables imaging depths of hundreds of microns in intact tissue, making this attractive for volumetric imaging applications. The development of fluorophores with photoemission beyond 1000nm provide the opportunity to develop novel fluorescence microscopes sensitive to those wavelengths. Here, we present a shortwave-infrared line-scan confocal microscope that is capable of deep imaging of biological specimens, as demonstrated by visualization of labelled glomeruli in a fixed uncleared kidney at depths beyond 400 m. We also show imaging of brain vasculature labelled with the near-infrared organic dye indocyanine green, the shortwave-infrared organic dye Chrom7, and rare earth-doped nanoparticles, thus encompassing the entire spectrum detectable by a typical shortwave-infrared sensitive InGaAs detector.