Optical detection system

Abstract

Abstract A method and a system for detecting the spectral radiant energy which is characteristic of an explosion or fire. The disclosed example uses methane-air ignitions which are analyzed by first determining their particular spectral radiance and comparing it with background irradiance from stray and ambient sources. Optimum spectral ranges which indicate the characteristic signature for an explosion or fire from the methane-air ignitions are determined and a plurality of suitable optical detectors are selected for the ranges involved. When preselected combinations of values of ranges are sensed, circuitry is then activated to signal the the occurrance of the methane-air ignitions. Two embodiments of circuitry are disclosed, one of which uses logic gates and the other a bridge of optical detectors. Should the invention be used in a coal mine environment, the actuated signal can be used to trigger a quenching mechanism located near the ignition point. The simplified embodiment of the circuitry which employs a bridge circuit, has three detectors in their branches and a fourth element. Each detector is optically filtered. In this way one detector is responsive only to the center emission peak, and the other two respond to side bands where there is no emission from the fire or explosion. The fourth element is masked and does not respond to any radiant energy. When the bridge becomes unbalanced, indicating the occurrence of a sensed explosion, a triggering device can be actuated to suppress the explosion.

Inventors

• 👤 Martin Hertzberg
• 👤 Charles D Litton
• 👤 John N Murphy
• 👤 H Kenneth Sacks

Bibliographic Details