Abstract Kidneys, like other organs, have an inherent capacity to recover from acute injury; however, severe or recurrent injury can result in chronic kidney disease (CKD), the sequelae of which result in 82,000 deaths annually in the US alone. Regardless of the etiology of the initial injury, the common final pathway leading to- end stage renal disease is closely connected to fibrosis (excess or aberrant collagen distribution), one of the most important determinants of renal disease severity and prognosis. Histology is the gold standard for evaluation, typically using histochemical stains such as trichrome and PAS that highlight the presence of collagens and basement membrane, respectively. Nevertheless, these stains are not completely specific, can be technically challenging to perform well and reproducibly, and thus contribute to interobserver variability and a concomitant decrease in diagnostic precision. Moreover, they also require the preparation of extra slides and additional staining procedures, and thus increase cost and can prolong the diagnostic process. We propose to optimize, deploy, and test a new kind of microscope, DUET (DUal mode Emission and Transmission microscopy), developed at UC Davis, that will be a low-cost and very rapid solution for detection and digital characterization of the presence and distribution of collagen and other macromolecules, directly from standard formalin-fixed, paraffin-embedded hematoxylin and eosin-stained slides. Specifically, we will finalize the design of the hardware and software components of the instrument itself, validate imaging performance against standard histology and immunohistochemical stains for collagen and other components, and with the assistance of scientists at our partnering institutions (John Hopkins University and University of Buffalo) develop robust tools for analysis and quantitation of fibrosis. DUET instrument hardware will be shared with JHU to ensure that the methods are technically reproducible across multiple sites. The application leverages the expertise across three institutions in optics, biomedical engineering, renal pathology and novel artificial intelligence approaches. The goal of the project is development and validation of DUET, which promises to be a robust, inexpensive, and practical approach for the rapid and accurate evaluation of fibrosis, extensible to other renal pathologies, and indeed across other organs systems, with significant positive impact on disease research, clinical practice, and patient outcomes.