All Publications

  • 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

  • Fast pulse shaping for a novel gated electron mirror. The Review of scientific instruments Klopfer, B. B., Koppell, S. A., Bowman, A. J., Israel, Y., Kasevich, M. A. 2021; 92 (4): 043705


    We present the design and prototype of a switchable electron mirror, along with a technique for driving it with an arbitrary pulse shape. We employ a general technique for electronic pulse-shaping, where high fidelity of the pulse shape is required, but the characteristics of the system, which are possibly nonlinear, are not known. This driving technique uses an arbitrary waveform generator to pre-compensate the pulse, with a simple iterative algorithm used to generate the input waveform. This is a broadly applicable, general method for arbitrary pulse shaping. Driving our switchable electron mirror with a flat-top pulse, we demonstrate an improvement in rms error of roughly two orders of magnitude compared to an uncompensated waveform. Our results demonstrate the feasibility of high fidelity waveform reproduction in the presence of nonidealities, with immediate applications in the realization of novel electron optical components.

    View details for DOI 10.1063/5.0039523

    View details for PubMedID 34243461

  • 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