An effective pulse is determined based on a pulse signal corresponding to the rotation of the imaging core from a pulse signal corresponding to the A line representing the period of the light source, and the polarization state of light transmitted by the light transmitting / receiving unit is switched according to the effective pulse. A signal of interference light between the light received by the light transmitting / receiving unit and the reference light is acquired according to the effective pulse.光源の周期を表すＡラインに応じたパルス信号から、イメージングコアの回転に応じたパルス信号に基づいて有効パルスを決定し、光送受信部が送信する光の偏光状態を、該有効パルスに従って切り替える。光送受信部が受信した光と参照光との干渉光の信号を、有効パルスに従って取得する。
