PURPOSE: To suppress blooming or the degradation of a CCD by supplying a power supply voltage to the CCD only at the time of outputting a synchronizing signal from a laser unit.

CONSTITUTION: A power supply control part 35 controls turning-on/off of a switch 31 in accordance with the presence/absence of a synchronizing signal P from a laser unit 10; and when the signal P exists, the switch 31 is turned on to supply a voltage from a main power source 30 to a CCD power supply part 32, a clock generator 33, and a signal processing part 34. When the signal P from the unit 10 does not exist, the CCD power supply part 32 is set to the unoperated state, and consequently, a CCD 6 is not operated and photoelectric charge is not stored.