| 摘要 |
<p>The invention relates to the detection and measurement of a plurality of items (9). More particularly, the invention detects and measures average traffic (9) speed along a multiline highway (10). A preferred embodiment of the invention comprises: means (1, 2) for capturing first and second time-spaced images of a portion of a highway surface (10), over which traffic (9) is moving, and means (5) for superimposing Fourier transformed images onto a spatial light modulator (5) for producing an interference pattern, an optical processing system comprises a laser (6) and lenses (8) having differing optical characteristics in two transverse directions, so that inverse Fourier transforms of the interference patterns can be obtained. The speed of the traffic is calculated from the inverse transforms which are incident on a charge coupled device (14). The invention overcomes problems associated with previous systems in which vehicle characterisation was required.</p> |
