Associate Research Professor in the Department of Chemistry
Associate Research Professor of Physics (Secondary)
Faculty Network Member of the Duke Institute for Brain Sciences
Dr. 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.
Robles, Francisco E., et al. “Stimulated Raman scattering spectroscopic optical coherence tomography..” Optica, vol. 4, no. 2, Feb. 2017, pp. 243–46. Epmc, doi:10.1364/OPTICA.4.000243. Full Text
Villafana, T. E., et al. “High-resolution, three-dimensional imaging of pigments and support in paper and textiles.” Journal of Cultural Heritage, vol. 20, July 2016, pp. 583–88. Scopus, doi:10.1016/j.culher.2016.02.003. Full Text
Robles, Francisco E., et al. “Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography..” Optics Express, vol. 24, no. 1, Jan. 2016, pp. 485–98. Epmc, doi:10.1364/OE.24.000485. Full Text
Robles, Francisco E., et al. “Pump-probe imaging of pigmented cutaneous melanoma primary lesions gives insight into metastatic potential..” Biomed Opt Express, vol. 6, no. 9, Sept. 2015, pp. 3631–45. Pubmed, doi:10.1364/BOE.6.003631. Full Text
Wilson, Jesse W., et al. “Flexible digital signal processing architecture for narrowband and spread-spectrum lock-in detection in multiphoton microscopy and time-resolved spectroscopy..” The Review of Scientific Instruments, vol. 86, no. 3, Mar. 2015. Epmc, doi:10.1063/1.4916261. Full Text
Park, Jong Kang, et al. “Femtosecond pulse train shaping improves two-photon excited fluorescence measurements..” Optics Letters, vol. 39, no. 19, Oct. 2014, pp. 5606–09. Epmc, doi:10.1364/ol.39.005606. Full Text
Robles, Francisco E., et al. “Femtosecond pulse shaping enables detection of optical Kerr-effect (OKE) dynamics for molecular imaging..” Optics Letters, vol. 39, no. 16, Aug. 2014, pp. 4788–91. Epmc, doi:10.1364/ol.39.004788. Full Text
Villafana, Tana Elizabeth, et al. “Femtosecond pump-probe microscopy generates virtual cross-sections in historic artwork..” Proceedings of the National Academy of Sciences of the United States of America, vol. 111, no. 5, Feb. 2014, pp. 1708–13. Epmc, doi:10.1073/pnas.1317230111. Full Text