All Publications

  • Wide-field fluorescence lifetime imaging of neuron spiking and subthreshold activity in vivo. Science (New York, N.Y.) Bowman, A. J., Huang, C., Schnitzer, M. J., Kasevich, M. A. 2023; 380 (6651): 1270-1275


    The development of voltage-sensitive fluorescent probes suggests fluorescence lifetime as a promising readout for electrical activity in biological systems. Existing approaches fail to achieve the speed and sensitivity required for voltage imaging in neuroscience applications. We demonstrated that wide-field electro-optic fluorescence lifetime imaging microscopy (EO-FLIM) allows lifetime imaging at kilohertz frame-acquisition rates, spatially resolving action potential propagation and subthreshold neural activity in live adult Drosophila. Lifetime resolutions of <5 picoseconds at 1 kilohertz were achieved for single-cell voltage recordings. Lifetime readout is limited by photon shot noise, and the method provides strong rejection of motion artifacts and technical noise sources. Recordings revealed local transmembrane depolarizations, two types of spikes with distinct fluorescence lifetimes, and phase locking of spikes to an external mechanical stimulus.

    View details for DOI 10.1126/science.adf9725

    View details for PubMedID 37347862

  • Nanosecond Photoemission near the Potential Barrier of a Schottky Emitter PHYSICAL REVIEW APPLIED Reynolds, J. L., Israel, Y., Bowman, A. J., Klopfer, B. B., Kasevich, M. A. 2023; 19 (1)
  • Transmission electron microscopy at the quantum limit APPLIED PHYSICS LETTERS Koppell, S. A., Israel, Y., Bowman, A. J., Klopfer, B. B., Kasevich, M. A. 2022; 120 (19)

    View details for DOI 10.1063/5.0086148

    View details for Web of Science ID 000795812900008

  • Resonant Electro-Optic Imaging for Microscopy at Nanosecond Resolution. ACS nano Bowman, A. J., Kasevich, M. A. 2021


    We demonstrate an electro-optic wide-field method to enable fluorescence lifetime microscopy (FLIM) with high throughput and single-molecule sensitivity. Resonantly driven Pockels cells are used to efficiently gate images at 39 MHz, allowing fluorescence lifetime to be captured on standard camera sensors. Lifetime imaging of single molecules is enabled in wide field with exposure times of less than 100 ms. This capability allows combination of wide-field FLIM with single-molecule super-resolution localization microscopy. Fast single-molecule dynamics such as FRET and molecular binding events are captured from wide-field images without prior spatial knowledge. A lifetime sensitivity of 1.9 times the photon shot-noise limit is achieved, and high throughput is shown by acquiring wide-field FLIM images with millisecond exposure and >108 photons per frame. Resonant electro-optic FLIM allows lifetime contrast in any wide-field microscopy method.

    View details for DOI 10.1021/acsnano.1c04470

    View details for PubMedID 34546704

  • Fast pulse shaping for a novel gated electron mirror REVIEW OF SCIENTIFIC INSTRUMENTS Klopfer, B. B., Koppell, S. A., Bowman, A. J., Israel, Y., Kasevich, M. A. 2021; 92 (4)

    View details for DOI 10.1063/5.0039523

    View details for Web of Science ID 000638192900001

  • High-extinction electron pulses by laser-triggered emission from a Schottky emitter APPLIED PHYSICS LETTERS Israel, Y., Bowman, A. J., Klopfer, B. B., Koppell, S. A., Kasevich, M. A. 2020; 117 (19)

    View details for DOI 10.1063/5.0028493

    View details for Web of Science ID 000590844900001

  • Design for a 10keV multi-pass transmission electron microscope. Ultramicroscopy Koppell, S. A., Mankos, M., Bowman, A. J., Israel, Y., Juffmann, T., Klopfer, B. B., Kasevich, M. A. 2019; 207: 112834


    Multi-pass transmission electron microscopy (MPTEM) has been proposed as a way to reduce damage to radiation-sensitive materials. For the field of cryo-electron microscopy (cryo-EM), this would significantly reduce the number of projections needed to create a 3D model and would allow the imaging of lower-contrast, more heterogeneous samples. We have designed a 10keV proof-of-concept MPTEM. The column features fast-switching gated electron mirrors which cause each electron to interrogate the sample multiple times. A linear approximation for the multi-pass contrast transfer function (CTF) is developed to explain how the resolution depends on the number of passes through the sample.

    View details for DOI 10.1016/j.ultramic.2019.112834

    View details for PubMedID 31520925

  • Electro-optic imaging enables efficient wide-field fluorescence lifetime microscopy. Nature communications Bowman, A. J., Klopfer, B. B., Juffmann, T. n., Kasevich, M. A. 2019; 10 (1): 4561


    Nanosecond temporal resolution enables new methods for wide-field imaging like time-of-flight, gated detection, and fluorescence lifetime. The optical efficiency of existing approaches, however, presents challenges for low-light applications common to fluorescence microscopy and single-molecule imaging. We demonstrate the use of Pockels cells for wide-field image gating with nanosecond temporal resolution and high photon collection efficiency. Two temporal frames are obtained by combining a Pockels cell with a pair of polarizing beam-splitters. We show multi-label fluorescence lifetime imaging microscopy (FLIM), single-molecule lifetime spectroscopy, and fast single-frame FLIM at the camera frame rate with 103-105 times higher throughput than single photon counting. Finally, we demonstrate a space-to-time image multiplexer using a re-imaging optical cavity with a tilted mirror to extend the Pockels cell technique to multiple temporal frames. These methods enable nanosecond imaging with standard optical systems and sensors, opening a new temporal dimension for wide-field low-light microscopy.

    View details for DOI 10.1038/s41467-019-12535-5

    View details for PubMedID 31594938