Hughes Aircraft Company

Wayde H Affleck

David B Cohn

Thomas P Moser

George D Lawrence

Robert E Eldridge

The invention is a laser power limiter. The limiter incorporates a layer of plasma forming particulate material supported optically in front of a sensor. A focussing means is positioned optically forward of the particulate layer to concentrate incident threat radiation on the particulate layer. The position of the particulate layer relative to the focussing means is selected such that the focal area encompassed by concentrated incident radiation encompasses a sufficient number of particulates to insure protective plasma formation and to insure that damage level incident radiation will be concentrated to an energy level exceeding the plasma formation threshold of the particulate material. The particulate layer is supported on a rotating window such that new areas of the layer can be exposed to incident radiation after a damage radiation incident.

Surface particulate laser power limiter which generates a plasma

A laser preionization electrode (15, 17) formed of a dielectric tube (16) of square cross-section enclosing an electrode (18) of circular cross-section, the electrode (18) being of a large diameter on the order of 6.35 millimeters. A pair of such electrodes (15, 17) are located on either side of a main electrode (11) in a laser with the result that longer length preionization electrodes may be constructed while eliminating alignment problems of the prior art.

Preionization electrode for pulsed gas laser

A directly heated catalyst 10 is comprised of an electrically conductive ceramic substrate 12 having a catalytic coating 14 applied to at least an outer surface thereof. In an illustrative embodiment of the invention the catalytic coating is a noble metal or non-noblemetal coating. In accordance with one embodiment of the invention a high surface area form of platinum (Platinum Black) is deposited upon a ceramic substrate, such as a substrate comprised of SiC or SnO.sub.2. The coating is brought to its activation temperature by resistively heating the substrate with an electrical current. A temperature sensing device (20, 40), such as a thermocouple or a thermostat, may be coupled to the catalyst structure for sensing the temperature of the catalyst to control the heater current supplied to the substrate. The catalyst is shown to be useful for CO.sub.2 gas lasers.

Directly heated ceramic catalyst support

A piezoelectric fan is comprised of two counter-oscillating flexible blades that are driven at resonance by a bimorph comprised of two piezoceramic bending elements. The fan is provided within the flow duct of a circulating gas laser. The operation of the piezoelectric fan serves to create a flow of a laser gas medium in a desired direction through the flow duct, thereby replenishing the gas medium between a pair of laser electrodes. The fan has no wearing elements, such as bearings, and requires no bearing lubricant resulting in the elimination of lubricant hydrocarbon and bearing particulate contamination of the laser gas medium.

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El Segundo, CA, United States of America

Wayde H Affleck