We present a coordinate-sensitive detector with a gallium-arsenide photocathode-a vacuum photoelectronic device featuring microchannel gain and a multi-element collector-which had several prototypes manufactured. Quantum efficiency of the photocathode amounts to 48% at maximum, its sensitivity range spans from 350 to 900 nm. The microchannel gain unit consists of two plates with an ion barrier film at the entrance. The coordinates of electron avalanches are determined using a 16-element collector. The spatial resolution, diameter of the working field, and temporal resolution of the detector are equal to 25 μm, 18 mm, and about 1 μs, respectively.