polar activation

in order to determine the position of the theodolite, a star-observing tv system with adjustable image position and fixed focal length was developed.

为了标定试验设备空间位置，研制了一种像面位置可调的定焦距标星电视系统。

in order to measure quantity of target-axis offset more conveniently, photograph and image pick-up usually use fixed focal length and angle of view.

摄影和摄像测量中，为计算脱靶量方便，通常都采用固定焦距、固定视场。

this thesis analyses the design and simulation of micro optical lens system having a fixed focal length, improving on it, making with simulation and design preferable.

本文首先介绍了微型光学镜头的发展状况，分析了光学镜头与影像感测元件之间的匹配问题，并对定焦镜头的技术参数以及发展历程作了详细的介绍。

Polaroid cameras have a fixed focal length.

偏光照相机有固定的焦距。