| 摘要 |
A camera includes a photocathode operable in a night mode wherein electrons are generated in response to incident light, an active pixel sensor including an array of pixels for sensing electrons in the night mode, a power supply for energizing the photocathode in the night mode in response to a control signal, and a power supply control circuit for providing the control signal to the power supply in response to a sensed incident light level. The control signal may be a gating signal having a duty cycle that increases as the sensed incident light level decreases. The camera may be operable in a day mode wherein a fraction of the incident light is transmitted through the photocathode and is sensed by the active pixel sensor. The camera may further include an electron shielded light detector. A light detector signal generated by the electron shielded light detector may be used to control switching between the day mode and the night mode. |
