The SR400 Dual-Channel Photon Counter features a highly advanced photon counting approach without the complication of earlier counting systems. It eliminates the complexity of mixing and matching different parts like amplifiers, discriminators, gate generators and counters. This compact equipment incorporates all these functions into a single, less complicated microprocessor controlled instrument. This equipment can perform background subtraction, synchronous detection, source compensation and pile up correction. The counters of SR400 enables the user to count for a fixed amount of time, until a specific number of counts are received.