| 摘要 |
Infrared radiation from a light source (10) such as a laser diode illuminates the field of view of a surveillance camera (14). The amount of illumination is varied in intervals (fig. 3), which may, for example, be about 3/4 of a second, by varying the power applied to the light source. The radiation may emanate from optical fibers (12) surrounding a camera lens (14), or through other ports. The power to the laser diode (10) may be altered in response to background light sensed by a photo cell (51).
|
