  OPTIMA is a small, versatile high-speed photometer which is primarily
intended for time resolved observations of young high energy pulsars at optical
wavelengths. The detector system consists of eight fiber fed photon counters
based on avalanche photodiodes, a GPS timing receiver, an integrating CCD
camera to ensure the correct pointing of the telescope and a computerized
control unit. Since January 1999 OPTIMA proves its scientific potential by
measuring a very detailed lightcurve of the Crab Pulsar as well as by observing
cataclysmic variable stars on very short timescales. In this article we
describe the design of the detector system focussing on the photon counting
units and the software control which correlates the detected photons with the
GPS timing signal.
