| 摘要 |
PROBLEM TO BE SOLVED: To reduce measurement errors contained in normalization data.SOLUTION: A control circuit 36 causes a diode 10 to emit a laser beam and turning around of a pulse PA to start by outputting a control pulse to a pulse phase difference encoding circuit 32 via an OR gate 41. A comparator 31 subjects to waveform shaping a light reception pulse provided from an operational amplifier 13 via a switch 35 to output this pulse to the pulse phase difference encoding circuit 32 as a pulse PB. The control circuit 36 outputs at timing t2 the control pulse to the pulse phase difference encoding circuit 32 via the OR gate 41, outputs a substitute pulse PC1 to the pulse phase difference encoding circuit 32 via the switch 35 and the comparator 31, and outputs at timing t3 later than the timing t2 by a fixed period Ts a substitute pulse PC2 to the pulse phase difference encoding circuit 32 via an OR gate 42. An arithmetic processing circuit 34 calculates normalization data by using phase differences Da, Db and Dc. |
