| 摘要 |
<p>Apparatus for measuring an opaque object including a frame, a transparent support in the frame for supporting an object to be measured, a light source and a transmitted light detection system on opposite sides of the support, the detection system including a measuring bridge containing a window defined by an overlapping area 2.1 of two slots in bodies which are relatively movable so that the window can linearly scan the body to be measured. The bodies may comprise inner and outer tubes, the outer tube being opaque apart from a part-helical slot and the inner tube being of glass which is silvered except for a longitudinal strip. Photodetectors may be housed at each end of the inner tube and receive light by multiple reflections from the silvered wall of the inner tube. The inner tube may also include a ribbed transparent bar to refract light entering the inner tube. The outer tube may be rotated in synchronism with translation of the bridge relative to the object and may carry a pulse generator connected to a counter controlled by the output of the photosensor(s). <IMAGE></p> |
