Summary We present an integrated light‐electron microscope in which an inverted high‐NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high‐resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub‐10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum‐compatible immersion oil. For a 40‐nm‐diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry.
Ultrafast electron pulses enable imaging of transient dynamics with nanometer and femtosecond resolution. Such pulses are typically created by illuminating a flat photocathode or a cold-field emitter with femtosecond laser pulses. [1,2] Using a cold field emitter, an ultrafast Scanning Electron Microscope (USEM) has been realized enabling to image charge carrier diffusion in time and spatial domain. [3] Another approach to achieve ultrafast electron pulses is to use beam blankers using GHz magnetic or electric fields with resonant cavities, hence such blankers are relatively large. [4,5] Recently, we presented the concept of a laser-triggered beam blanker for use in regular EMs that allows easy and quick switching between continuous-beam and ultrafast modes of operation.[6] In this concept we propose to use a micro fabricated beam blanker controlled by a photoconductive switch, which is illuminated with femtosecond laser pulses, shown in Figure 1. Using COMSOL simulations we show that our design can in principle deliver sub 100 fs electron pulses by limiting the dimensions of the device to micrometer scales. We will also discuss the performance enhancement of the Auston switch using plasmonic contact electrodes. [6] We fabricated and integrated the beam blanker and a LT-GaAs photoconductive switch in one micrometer scale device. The ultrafast blanker is built on top of a LT-GaAs chip. Also a stick is designed containing the blanker into the beam line of a commercial Quanta FEG SEM. Finally we will present our progress towards experimental realization and characterization of an ultrafast beam blanker, showing laser-triggered electron beam deflection. With a single photon detector we show that electron pulses triggered with a femtosecond laser pulse are created, as indicated in Figure 2.
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