SOUND MEASUREMENT METHOD

WIPO Patent Application WO/2022/024217

A1

Provided is a technology that is for measuring a sound-induced optical phase modulation amount and is not affected by noise included in an average light intensity. This method comprises: an interference light generation step for obtaining, from light that has been emitted from a light source, first light including light optically modulated in phase by a sound measurement unit and second light that is different from the first light and includes light optically modulated in phase by the sound measurement unit; a first photodetection step for obtaining a first electrical signal from the first light; a second photodetection step for obtaining a second electrical signal from the second light; and a differential signal generation step for obtaining a differential signal that is the difference between the first electrical signal and second electrical signal. The phase of the light that is included in the first light and has been optically modulated in phase and the phase of the light that is included in the second light and has been optically modulated in phase are in an inverse relationship. A sound-induced optical phase modulation amount φs is measured as the current Δi of the differential signal expressed by the equation Δi = βIAcos(φs + φ0) (where β is a prescribed constant, IA is the interference fringe amplitude, and φ0 is the optical phase modulation amount caused by factors other than the sound).

ISHIKAWA KENJI (JP)
SHIRAKI YOSHIFUMI (JP)
MORIYA TAKEHIRO (JP)
HITACHI KENICHI (JP)
ISHIZAWA ATSUSHI (JP)
OGURI KATSUYA (JP)

PCT/JP2020/028872

February 03, 2022

July 28, 2020

Click for automatic bibliography generation  

NIPPON TELEGRAPH & TELEPHONE (JP)

G01H9/00

JPH035875Y2	1991-02-14
JPH05172738A	1993-07-09

NAKAO, Naoki et al. (JP)

View/Download PDF      PDF Help

Previous Patent: SETTING-OFF ASSISTANCE DEVICE

Next Patent: POWER CONVERSION DEVICE