| 摘要 |
A device (19), for measuring changes in the intensity of a beam (52) of ultra-violet light, includes a gas tight container (10) having a window (11) translucent to ultra-violet light and containing detector means (12a, 20) sensitive to changes in the amount of ultra-violet light entering the container. The detector means (12a) might be a gas, ionisable by ultra-violet light, which fills the container (10), or a plate (20) having photo-electric sensitivity to ultra-violet light. The device includes means (13, 14, 15, 17. 17; 25, 26, 27, 28) for measuring the ultra-violet light. The device can be used as a gas detector, measuring the loss in ultra-violet light in a beam (52) from a lamp (51) crossing a passage (50) through which flows an airflow containing a contaminant gas of the type which absorbs or is ionised by ultra-violet light. <IMAGE> |
