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Dr. Martin Fischer’s research focuses on exploring novel nonlinear optical contrast mechanisms for molecular imaging. Nonlinear optical microscopes can provide non-invasive, high-resolution, 3-dimensional images even in highly scattering environments such as biological tissue. Established contrast mechanisms, such as two-photon fluorescence or harmonic generation, can image a range of targets (such as autofluorescent markers or some connective tissue structure), but many of the most molecularly specific nonlinear interactions are harder to measure with power levels one might be willing to put on tissue. In order to use these previously inaccessible interactions as structural and molecular image contrasts we are developing ultrafast laser pulse shaping and pulse shape detection methods that dramatically enhance measurement sensitivity. Applications of these microscopy methods range from imaging biological tissue (mapping structure, endogenous tissue markers, or exogenous contrast agents) to characterization of nanomaterials (such as graphene and gold nanoparticles). The molecular contrast mechanisms we originally developed for biomedical imaging also provide pigment-specific signatures for paints used in historic artwork. Recently we have demonstrated that we can noninvasively image paint layers in historic paintings and we are currently developing microscopy techniques for use in art conservation and conservation science. Fischer is a research professor in the Departments of Chemistry and Physics.

Dr. David Grass’s research interests are novel nonlinear microscopy techniques such as pump-probe microscopy. Pump-probe microscopes not only provide image contrast, but also resolve the ultrafast excited state dynamics of the sample providing high chemical specificity. The broad range of nonlinear optical processes provides molecular contrast without the need for exogenous labels and thus preserves the local biochemical environment of the target molecules. Dr. Grass also focuses on experimental and data driven methods to analyze and interpret data from nonlinear microscopes to simplify usage of our advanced optical microscopes.