drawtube

n.

（显微镜的）镜筒，伸缩管；

1. Finally, inside this reflection of the secondary, you can see the focuser drawtube and your eye.
   最后，在副镜的反射像中，你能看到调焦座的伸缩管和你的眼睛的像。

Martin Drawtube Telescope
.965 rough focus drawtube wobbly
Dynamic Analysis of CCD Drawtube of the Lightweight Space Camera
Realtime Measurement of Bend of Periscope Drawtube by Linear Array CCD
Apparatus for adjusting the position of a drawtube in an optical instrument
Apparatus for adjusting the position of a drawtube in an optical instrument
A study on a multi-controller design of the drawtube for aerial boom refueling
Design and Lightweight Research of Cassegrain Drawtube in Space Remote Instrument
Analysis of Excitation Response Caused by the Periscope Drawtube Abstract
Approach to Improve Response Speed of Drawtube-Scan-Velocity Control System for TDI Side-Glance Aeronautical Camera