Abstract: A vacuum envelope having a longitudinal axis and a light input faceplate disposed coaxial of the axis and at one end of the tube includes therein coaxially of the axis adjacent the faceplate a photocathode which is responsive to an optical pulse train to emit electrons in the envelope in a direct proportion to incident photon flux of the optical pulse train. Electric field deflection plates are disposed within the envelope and spaced along the longitudinal axis from the photocathode toward the other end of the tube to produce an electric field perpendicular to the longitudinal axis to deflect the electrons. A readout device is disposed within the envelope and coaxial of the axis at the other end of the tube to provide a readout for the tube. A magnetic focusing device is disposed externally of the envelope and coaxial with the longitudinal axis to provide a magnetic field within the envelope perpendicular to the electric field to focus the electrons on the readout device. Several embodiments are disclosed.