Abstract: An explosive gas detector wherein power to a catalytic impedance element is held at a constant impedance level via a D.C., amplified, automatic bridge balancing circuit, and gas levels are indicated by an electrical meter connected between the output of a bridge and an adjustable level D.C. bias.

Abstract: An explosive gas detector employing an electrically conductive element which, when powered, changes temperature in the presence of an explosive gas, and a control circuit which senses the increases in temperature and decreases the power input to the element as an inverse function of changes in temperature of the element. The level of electrical power provided the element is indicative of the concentration of explosive gas present.

Abstract: A hydrogen fluoride/deuterium fluoride chemical laser having low concentration of deactivants is provided by the application of external heat rather than by internal combustion to cause thermal decomposition of the normal diatomic fluorine to convert it to atomic fluorine. This is accomplished by external heating of inert gases that then heat the diatomic fluorine or by directly heating from an external source the diatomic fluorine to form atomic fluorine. The formed atomic fluorine is then mixed with hydrogen and/or deuterium in a laser chamber to produce lasing of the gases when brought together in a conventional manner and therefrom a laser output.

Abstract: An FM radar for the measurement of coal thickness wherein an FM transmitter is modulated by the combination of two signals, one, for example, being of a frequency of 100 Hz, and the other being of a frequency of 15 Hz. A horn-type antenna is used which is filled with a material having a dielectric constant approximating that of coal, the antenna being positioned flush against the coal.

Abstract: A continuous wave chemical laser device in which useful species such as free radicals as vibrationally excited molecules are generated by interaction of suitable chemicals such as hydrogen, sulfur hexafluoride, and carbon dioxide with laser radiation. The chemical laser device is capable of generating active species by interaction of its own laser radiation after first being initiated by a suitable initiator. The chemical reactions involved can take place at atmospheric pressure or higher and overcome disadvantages of ordinary chemical lasers.

Abstract: Method for producing continuous wave chemical laser output in which useful species such as free radicals as vibrationally excited molecules are generated by interaction of suitable chemicals such as hydrogen, sulfur hexafluoride, and carbon dioxide with initiator laser radiation. The chemical laser output is sustained by feeding back a portion of the laser output after first being initiated by a suitable initiator. The chemical reactions involved can take place at atmsopheric pressure or higher and overcome disadvantages of ordinary chemical lasers.

Abstract: A mechanism for the protection of optical glass plates against high energy laser radiation effects. The mechanism includes a water coated or water impregnated film positioned in a manner to shield the optical plates and absorb radiation from an attacking high energy laser source. An automatic means is provided for advancing the film when it experiences a rapid rise in temperature.