| 摘要 |
<p>The microfiche is laid onto a fixed glass plate and illuminated from underneath. An objective is supported inside an outer sleeve on four pins at 90 degrees to each other and locating in slots in the objective mounting. This allows axial adjustment for focussing while anabling the lens to be tilted to align the optic axis perpendicular to the microfiche. The image is projected via an overhead, angled mirror (25) and the focus control is by a geared control knob (40). The alignment aid for the objective allows high quality projection without precision mountings for the objective.</p> |
