| 摘要 |
<p>The instrument, which avoids "manipulative imprecisions involved in lens mounting, is a design giving immediate direct double axis reading and is based on bi-lateral scales incorporating horizontal and vertical graduated sliders. The vertical centring w.r.t. the frame is carried out using the graduated vertical support (4). The horizontal support (1) governs horizontal frame positioning while a sliding scale serves to fix the semi eye separation distance. A second slider (3) positions the focus. All sliding scales can be fixed in their runs by screws. The instrument is used in conjunction with a translucent plate which may be translated independently of the frame and on which the normalised traces of various lens diameters are superimposed to match the frame opening.</p> |
