Besides, the focus vibration control device 40 is configured to set the vibration frequency (fs) so that the vibration frequency (fs) may be nearly equal to Ns times (Ns is integer ≥1) of a basic frequency, where 1/Ti which is a reciprocal of an imaging period Ti during the TDI drive of the imaging apparatus 20 is regarded as the basic frequency. また、焦点振動制御装置40は、撮像装置20におけるTDI駆動での撮像期間Tiの逆数1/Tiを基本周波数として、振動周波数fsが基本周波数のNs倍(Nsは1以上の整数)に略一致するように、振動周波数fsを設定する。 - 特許庁