[5] MORITA T,NIINO T,ASAMA H.Rotational feedthrough using ultrasonic motor for high vacuum condition[J].Vacuum,2002,65:85-90
[6] MORITA T,TAKAHASHI S,ASAMA H,et al..Rotational feedthrough using an ultrasonic motor and its performance in ultra high vacuum conditions[J].Vacuum,2003,70:53-57
