Clamped cathode power supply for image intensifier
View Patent ↗A power supply for an image intensifier, the power supply including a DC voltage source generating a photocathode voltage; a bright source protection (BSP) resistor in series with the DC voltage source; and an oscillator in parallel with the DC voltage source and the BSP resistor, the oscillator providing an AC voltage component, the AC voltage component having a fixed pulse width, the AC voltage component being coupled to the photocathode by a diode, the pulse width and shape of the AC voltage component on the photocathode being determined by the photocathode current.
1. A power supply for an image intensifier, the power supply comprising:
a DC voltage source generating a photocathode voltage;
a bright source protection (BSP) resistor in series with the DC voltage source; and
an oscillator in parallel with the DC voltage source and the BSP resistor, the oscillator providing an AC voltage component, the AC voltage component having a fixed pulse width, the AC voltage component being coupled to the photocathode by a diode, the pulse width and shape of the AC voltage component on the photocathode being determined by the photocathode current.
2. The power supply of claim 1 wherein:
the anode of the diode is connected to the photocathode and the cathode of the diode is connected to the oscillator.
3. The power supply of claim 1 wherein:
frequency of the AC voltage component is fixed.
4. The power supply of claim 1 wherein:
amplitude of the AC voltage component is fixed.
5. The power supply of claim 1 wherein:
frequency and amplitude of the AC voltage component are fixed.
6. The power supply of claim 5 wherein:
frequency, amplitude and pulse width of the AC voltage component are factory configurable.
7. The power supply of claim 6 wherein:
a discharge rate of the photocathode under low light situations is less than a re-charge rate supplied by the power supply and the discharge rate of the photocathode under high light conditions is greater than the re-charge rate supplied by the power supply.
8. An image intensifier comprising:
a photocathode;
a microchannel plate;
a phosphor screen; and
a power supply including:
a DC voltage source generating a photocathode voltage;
a bright source protection (BSP) resistor in series with the DC voltage source; and
an oscillator in parallel with the DC voltage source and the BSP resistor, the oscillator providing an AC voltage component, the AC voltage component having a fixed pulse width, the AC voltage component being coupled to the photocathode by a diode, the pulse width and shape of the AC voltage component on the photocathode being determined by the photocathode current.
9. The image intensifier of claim 8 wherein:
the anode of the diode is connected to the photocathode and the cathode of the diode is connected to the oscillator.
10. The image intensifier of claim 8 wherein:
frequency of the AC voltage component is fixed.
11. The image intensifier of claim 8 wherein:
amplitude of the AC voltage component is fixed.
12. The image intensifier of claim 8 wherein:
frequency, amplitude and duty cycle of the AC voltage component are fixed.
13. The image intensifier of claim 12 wherein:
frequency, amplitude, and pulse width of the AC voltage component are factory configurable.