| 摘要 |
PROBLEM TO BE SOLVED: To measure photoacoustic vibration with high sensitivity and accuracy.SOLUTION: The physical property measuring device 10 on the basis of photoacoustic vibration includes: an LED 12 which is an optical input element; an acoustic detection sensor 14; an amplifier 30 whose input terminal is connected to a signal output terminal 15 of the acoustic detection sensor 14; a phase compensation circuit 32 which is disposed between an output terminal of the amplifier 30 and a signal input terminal 21 of an LED drive circuit 16 and changes the frequency of a signal so that a phase difference between an input waveform to the LED drive circuit 16 and an output waveform from the acoustic detection sensor 14 becomes zero; a frequency change detection unit 34 for detecting an amount of change of a frequency of a self-oscillation vibration occurring due to zero compensation of the phase difference, according to a state of a medium 6 which is an object; and an output unit 40 for preliminarily obtaining and storing a characteristic correlation 38 between the amount of change of the frequency and a characteristic value of the object, and outputting the characteristic value of the object corresponding to the detected amount of change of the frequency. |
