焦距-焦长
external workfocal length
螺距补偿
pitch compensation
screw distance compensation
双源距补偿中子测井
cDN
compensated dual neutron log
相间多相补偿距离继电器
polyphase compensated distance relay
凹透镜焦距
focal length of concave lens
变焦距变波长的非准确联合变换相关
inaccurate joint transform correlation with change
变焦距光学系统
variable focal length optical system
Zoom optical system
zoom system
变焦距立体显微镜
zoom stereoscopic microscope