| 摘要 |
A detector (2) of combustion products from a fire comprises an enclosure (4) having an opening (6) and a focussing means (24, 26) arranged for converging light from the opening (6) to a focus (12). A detector (14) is prevented from detecting the light at the focus (12) by a screening member (16). When a combustion product is present in the enclosure (4) the light is either refracted or scattered off-focus where it can then be detected by the detector (14). <IMAGE> |
