| 摘要 |
PURPOSE:To decide easily the position of a vibration node point by comparing the size of a respective fringe line of interference fringes, by making a phase shifting of an optical axis phase modulation of a laser beam to the extent that the stripes are able to be observed periodically from a reference phase. CONSTITUTION:An output of a waveform shaping circuit 3 is delayed by a delay circuit 17 and a phase adjustment between the output and the vibration state of an object 8 by an amplifier 7 system is made. The output of the circuit 17 is divided into two at a dividing circuit 18 and one of its complementary output is made to a trigger signal of a monostable multivibrator 21 via a monostable multivibrator 19 and the other of the output is made to a trigger signal via a delay circuit 20. By this way, a modulated pulse signal in which an optical axis modulated phase is shifted at every period by them is taken out, and a modulated pulse signal of a reference phase is taken to the monostalbe multivibrator 19 and a modulated pulse signal shifted by several percent from a reference phase is taken to the monostable multivibrator 21. Both modulated pulse signals are synthesized by an NOR circuit 22 to be made a modulated pulse signal of an optical modulator 5. |
