Position-sensitive detector for the 6-m optical telescope

A position-sensitive detector (PSD) for photometrical and spectral observation on the 6-m optical telescope of the Special Astrophysical Observatory (Russia) is described. The PSD consists of: a position-sensitive tube; amplifiers of output signals; analog-to-digital converters (ADC) and a digital logic plate, which produces a signal for ADC start and an external strobe pulse for reading the information by registration system. If necessary, a thermoelectric cooler can be used. The position-sensitive tube has the following main elements: a photocathode, electrodes of inverting optics, a block of microchannel plates and a quadrant position-sensitive collector.The main parameters of the PSD are: the diameter of the sensitive surface is 25 mm; the spatial resolution is better than 100 μm in the centre and a little worse on the periphery; the dead time is near 0.5 μs; the detection quantum efficiency is defined by the photocathode and it is not less than 0.1, as a rule; dark current is about hundreds of cps, or less, when cooling. PSD spectral sensitivity depends on the type of photocathode and input window material. We use a multialkali photocathode and a fiber or UV-glass, which gives the short-wave cut of 360 or 250 nm, respectively.