| 摘要 |
<p>An optical imaging system comprises a solid state electrically controlled variable density optical filter, the filter comprising a polymer dispersed liquid crystal device (6) disposed adjacent, for example, to an image forming lens (5) of the system, and drive means (7) for causing a common electric field to be set up in the liquid crystal device (6) over the active area thereof, the electric field being variable for controllably varying image intensity whilst substantially maintaining the definition of the image.</p> |
