| 摘要 |
<p>The reflective equipment has a matrix of separate flat mechanical components turning through 180 deg. on axes in their plane between end positions so as to look bright in one and dark in the other. Each component has a first linear polarisation filter whose direction is at 45 deg. to the axis of rotation. At a distance from this filter sufficient not to impede its rotation is a second such filter of direction also at 45 deg. to the axis. This in one end position the directions of the filters are parallel, and in the other at right angles to each other. The first filter has a non-transparent layer covering part of its surface and with a light-coloured reflective surface on one sided and a dark light-absorbent one on the other. The reflective surface is visible when the two polarisation directions are parallel, and the absorbent one when they are at right angles. A light source is mounted behind the filters.</p> |
