Liisa Hirvonen edited Method.tex  almost 9 years ago

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This investigation was performed using a dual mode cooled Hamamatsu C1790-13 EBCCD comprised of 512$\times$512 pixels where each pixel is 24$\times$24~$\mu$m in size. The photocathode in the EBCCD is a GaAsP plate with an approximate quantum efficiency of 50\% at 520~nm. Upon liberation from the photocathode, the photoelectrons are accelerated across a potential difference into a back-thinned CCD. The vacuum chamber has an aluminium sheet 1.3~mm from the cathode to protect the back-thinned CCD from back-scattered photoelectrons. During data acquisition, the EBCCD was cooled to an operation temperature of -15$^\circ$C and the EBCCD read-out was operated using the HiPic 7.1.0 software package from Hamamatsu, which acquired data using an exposure time of 10$\mu$s and a Super-High (EB?) gain.  The EBCCD was attached to the output port of an inverted Nikon Eclipse TE2000-E microscope. microscope, see Fig~\ref{fig1}a.  For the biological cell sample imaging, the microscope was used with a 100$\times$ 1.4NA air objective (Nikon) and for the 1951 USAF resolution test chart, chart (Fig~\ref{fig1}b),  the microscope was used with a 4$\times$ 0.13NA air objective (Nikon). 2,000 frames were collected for the biological cell sample and 30,000 frames were collected for the USAF test pattern. The exposure time was set to 10$\mu$s. 10$\mu$s, and the illumination intensity adjusted such that single photon event could be observed (Fig~\ref{fig1}c,d).  \subsection{Data processing}