Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1992-12-22
1994-01-18
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
359241, H01J 314, G02F 101, G02B 523
Patent
active
052801691
ABSTRACT:
Method and apparatus for limiting optical radiation to an optical sensor are disclosed for protecting the sensor against damage from high intensity optical radiation. A fixed electric field is established between a pair of spaced electrodes by connection of the electrodes to a DC voltage source. Small solid particles oscillate back and forth in the electric field between the electrodes. Incident optical radiation is focused at a focal plane at the oscillating solid particles, and energy transmitted through the oscillating particles is focused at the optical sensor. The transmittance of the particle-containing space is substantially constant for incident optical radiation intensity up to a threshold level below which the sensor is undamaged by the radiation. Above the threshold, oscillating particles are heated to a high temperature for vaporization, ionization and thermal expansion thereof for increased scatter and absorption thereby limiting optical radiation to the sensor to an intensity below which damage to the sensor occurs.
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Adamo Richard C.
Brown Robert A.
Honey Richard C.
Nashold Karen M.
Beckman Victor R.
Lee John R.
Nelms David C.
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