2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/195146We describe a UV photo-detector with single photon(electron) counting and imaging capability. It is based on a CsI photocathode, a GEM charge multiplier and a self triggering CMOS analog pixel chip with 105k pixels at 50 micron pitch. The single photoelectron produced by the absorption of a UV photon is drifted to and multiplied inside a single GEM hole. The coordinates of the GEM avalanche are reconstructed with high accuracy (4 micron rms) by the pixel chip. As a result the map of the GEM holes, arranged on a triangular pattern at 50micron pitch, is finely imaged.6 pages, 14 figures, presented at the 11th Vienna Conference on Instrumentation VIC 2007, submitted to Nuclear Instruments and Methods AInstrumentation and DetectorsAstrophysicsMedical Physicstext