Method and apparatus for limiting optical radiation intensity at an optical sensor using solid particles oscillating in an electric field

US5280169A · kind A · utility

Inventors

• Richard C. Honey · San Mateo, US
• Robert Allen Brown · Redwood City, US
• Karen Marie Nashold · San Francisco, US
• Richard C. Adamo · Palo Alto, US

Key dates

• Filing date: Dec 22, 1992
• Grant date: Jan 18, 1994
• Expiry date: Dec 22, 2012

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/009
• WIPO field: Optics
• WIPO sector: Instruments

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.