A method, system, and computer program product provide a shared virtual memory space via a cluster-aware virtual inputoutput server. In the time-of-flight mass spectrometer, the ion reflector has plural thin plate electrodes and a final electrode. The voltage comparator compares the terminal voltage of the capacitor with its input voltage and actuates the charging circuit or the discharging circuit according to a comparison result. There are, between the current source positive and negative poles serially connected transistor, regulation tube, with the regulation tube negative pole linked to the current source negative pole, and its positive pole, incorporated to form the primary current. The light absorbing layers are each provided at a place in close proximity to the focal point of one of the lenticular lenses and are separated from each other by a predetermined distance for forming light passing windows.