In MALDI TOF-MS a pulsed laser is used to vaporize and ionize the sample from a planchet placed directly in the acceleration region of the TOF-MS. The laser pulse repetition rate is low to moderate (10 Hz to 1 kHz), but the number of ions in each group reaching the detector is very large. Consequently, a  FASTFLIGHT-2  signal averager can be used to advantage in MALDI TOF-MS.

In this application, the acceleration potential is a constant HV from a Model 556-P (i.e. not pulsed), and the starting time for the time-of-flight is determined by the laser pulse. The laser provides an electronic trigger output pulse synchronized to each laser optical pulse, which is used to trigger the start of each scan in the FASTFLIGHT-2. Each ion that arrives at the microchannel plate detector cause a small pulse signal which is then amplified by the Model 9326-P preamplifier to match the input range of the digital signal averager. At its input, the FASTFLIGHT-2 incorporates an ADC (analog-to-digital converter) that periodically samples the input voltage at 500 ps intervals, and converts those samples to an 8 bit digital representation. The amplitude of the sampled signal is proportional to the number of molecular ions simultaneously arriving at the detector, while the arrival time, which is a measure of the mass-to-charge ratio, is determined by the sampling time at the maximum amplitude of the pulse. For better statistical precision, the centroid of the sampled pulse can be used to define the arrival time, which ultimately identifies the mass of the molecular ion.

To improve the signal-to-noise ratio, time-of-flight records from a large number of acceleration pulses are summed (and thereby linearly averaged) in the FASTFLIGHT-2 hardware memory. The final, summed spectrum is compressed and passed to the supporting computer to display the time-of-flight spectrum.