Optical switch

Abstract

An optical switch, which may be a part of a fuze for an explosive project, comprises a housing made up of a hollow cylindrical part with two end plates welded thereto and having a pair of aligned glass windows sealed through opposite sides for transmitting light transversely therethrough, a gas piston with O-ring seals slidable in the housing to define an end wall of a variable volume gas chamber therein and adapted to be moved by inertia during projectile launch to decrease the volume of the chamber and thereby increase the gas pressure, means for locking the piston in the new position, a valve in the housing for admitting a light attenuating gas to the chamber, an adjustable pressure relief valve in the housing adapted to open when the internal gas pressure exceeds the external pressure by a given amount, a light source positioned adjacent to the outside of one of the windows to project light through the windows and the attenuating gas, and a light-sensitive device positioned on the other side of the housing to receive the attenuated light. When the intensity of the light received by the device equals a critical value, the device responds by performing a desired function, such as arming a firing circuit of the fuze. The gas pressures in the chamber before and after piston movement are higher than a critical pressure at which the light reaching the output device has the critical value. When the projectile is projected to a desired altitude, the reduced atmospheric pressure causes the relief valve to open, reducing the chamber pressure below the critical pressure, thereby exciting the light sensitive device to arm the fuze. The switch may be used with a gas chamber of fixed volume, with a higher initial gas pressure.

Dependencies are inferred from the claim text.