For many years, André Lallemand (1904-1978) had been developing at the Paris Observatory a new light detector: the electronic camera, a much more sensitive device than the photographic plate. In this instrument, the image of the object under study is projected onto a photo-cathode; the resulting electrons are accelerated, then focused onto a sensitive plate to make an electronic image of the object.  However, the instrument, temporarily installed at Lick and over the long term at the Haute-Provence observatory, was not easy to use. It was abandoned as soon as CCD detectors made their appearance in the 1970s; these are now used everywhere for visible light imagery.

caption : The electronic camera at Lick Observatory - credits : Observatoire de Paris