| 摘要 |
<p>A pressure actuated light pen attached to the end of an optical fibre bundle has a retractable shutter mechanism at its forward end. The shutter mechanism comprises a plurality of wedge-shaped sections, resiliently urged in a forward direction to at least substantially close off light admittance, and moveable rearwards along inclined paths to produce an aperture at their forward ends, the light pattern at the aperture focussed on the ends of the fibres. - i</p> |
