Measurement of absolute optical length of Fabry-Perot cavity using frequency measurement

(Fourth report : An absolute optical distance measurement of a Fabry-Perot cavity with a movable mirror)

Abstract

An absolute optical distance of Fabry-Perot cavity can be determined by measuring its Free Spectrum Range(FSR). In the previous reports, we reported a FSR measurement method using electric optical modulator. Real time FSR measurement can be performed, because this method is based on the null-method. In this report, we demonstrate the capability of proposed method by measuring FSR of a Fabry-Perot cavity with a movable mirror.