Abstract: A method for avoiding damage to the eyes when using high-power lasers in the eye-transmissible spectral region is provided. By adding a laser or a radiation in the visible spectral region, the intensity of the radiation is increased as a function of time in the shape of a ramp from zero to higher values which lead to a conscious or reflex-type closing of the eyelids This therefore prevents the eyes from being damaged by the subsequent high-power laser beam.

Abstract: The invention relates to a sensor for use in the warhead of a missile, which can be used against helicopters, in that it is equipped with one or more high-resolution LRFs with respect to space and time, which identifies the helicopter on the basis of the common arrangement and size of the detected rotor blade selections with a numerical processor and activates an ignition device accordingly.

Abstract: A retromodulator in the form of a triple mirror with electromechanical transducer elements for planar deformation by which incident light radiation is retroflected in modulated form. At least one face of the retromodulator is formed as an oscillatory diaphragm which is excited to natural oscillations by the transducer elements. In a preferred form of realization, the oscillatory diaphragm comprises a piezoelectric foil, on whose inner side a reflecting layer is applied and on whose outer side electrodes are applied to which the modulation signal is applied.

Abstract: A window which is transparent to radiation in the visible, optical and near nfrared range but not transparent to the radiation of a laser, is protected against distruction or damage by the laser radiation. For this purpose the window itself is constructed of at least two layers of solid optical material which is also transparent to the high energy laser radiation. These layers form a cooling channel through which a gaseous or liquid coolant flows. The coolant is transparent to the visible and near infrared range, but opaque to the laser radiation.

Abstract: In a molecular laser a cold gas flow is mixed with the hot gas flow by inducing the cold gas flow through slots (13) arranged upstream of the neck (11) of the Laval nozzle (10) through which the hot gas stream flows. In this way a rapid mixing is accomplished for generating non-balanced conditions in a laser gas. Preferably the mixing takes place substantially in the nozzle neck.

Abstract: In a gasdynamic CO.sub.2 laser mixing of hot and cold gasses takes place simultaneously with causing an inversion. The cold gas is air supplied through a compressor at a pressure in the range of 1 to 10 bar into the combustion chamber. Preferably the compressor output is supplied to two points of the combustion chamber, namely a zone directly upstream of and adjacent to the Laval nozzle and a zone in the combustion chamber further removed from the Laval nozzle.

Abstract: A system for automatically firing or discharing a weapon, such as a mine, comprises acoustical sensors for the preliminary adjustment and firing of the weapon. An optical sensor is used in conjunction with the acoustical sensors. In a first step, prior to the first acoustical target acquisition, the target background is optically scanned to store first optical image values defining an optical image of the target background to determine a firing range and a firing horizon. Thereafter, an acoustical ranging is performed for the target acquisition. Then the optical scanning and storing is repeated with regard to a firing horizon and when a target approaches the firing horizon, to provide second optical image values which are compared with the first image values to provide, by signal differentiation, proof of the presence of a target at the firing horizon. The resulting signal is used to control the weapon.

Abstract: The efficiency of a chemically fuelled laser with regenerative cooling of its combustion chamber is increased by using the fuels as coolant in the diffuser. The heat resulting from this cooling in the diffuser is supplied in a regenerative manner to the combustion chamber or rather to the laser gas.

Abstract: The resonator of a gas dynamic laser, particularly, of a high power gas dynamic laser, is mechanically decoupled from the other components of the laser by a pair of elastic restoring ring membranes and stay bolts. The flow channel of the laser is mechanically connected through the ring membranes to the resonator. A pair of tubular, elastic sleeve membranes seal the flow channel in a vacuum tight manner. The laser beam decoupling elements are secured to bushings extending coaxially through said elastic tubular sleeve membranes. The restoring forces of the ring membranes are large relative to the differential force resulting from said tubular sleeve sealing membranes.

Abstract: Isotopes are separated from a gas mixture by accelerating the gas mixture containing the isotopes to ultrasonic speeds sufficient to bring the gas temperature to 150.degree. K or less. Simultaneously, the gas is subject to a pressure well above the vapor pressure of the gas at said temperature. Under these conditions the gas is subjected to a laser radiation having a wave length corresponding to the absorption line or band of the molecules containing the isotopes to be separated, whereby the molecules are excited so that they may be separated by conventional devices. The present apparatus has a high pressure reservoir supplying the gas mixture through a device for producing said ultrasonic speeds into an expansion chamber. As the gas flowing at said speeds is irradiated by the laser beam, it expands into a low pressure reservoir. The laser is arranged so that the laser beam extends across the expanding gas flow at a point where the expanding gas does not yet start to condense.

Abstract: The present method relates to exciting a gas dynamic CO.sub.2 laser, especially at high stagnation temperatures above 2500.degree. K and at a combustion chamber pressure above 50 bar. A liquid fuel and a liquid oxidizer are injected into the combustion chamber at these operating parameters and the produced laser gas is caused to flow through a Laval nozzle into a resonator. The flow cross sectional area of the Laval nozzle adjacent to the resonator is at least 100 times larger than the flow cross sectional area adjacent to the nozzle neck facing the combustion chamber. The flow of the laser gas through this nozzle cools the gas to about 300.degree. K, whereby an inversion state is produced. The laser for performing this type of operation has a combustion chamber connected through the above mentioned nozzle to a resonator which in turn is connected to a diffuser.

Abstract: In a laser gyroscope it is desirable for precision operation to eliminate or effectively compensate temperature variations, as well as manufacturing tolerances. To this end the present laser gyroscope has two ring lasers physically arranged so close to each other that there is an optimal thermic contact between the two ring lasers. Temperature sensors are arranged in contact with the resonator circumference to control a piezoelectric resonator tuning device in response to temperature variations to compensate the same. The modulators of the lasers are periodically switched, for example, with the aid of Faraday cells to reverse the travel direction of the travelling waves to thereby compensate for manufacturing tolerances, and any remaining temperature variations.

Abstract: In a laser system activated by a molecular gas there is provided a novel nozzle construction for the purpose of effecting expansion of the gas in a minimum period of time but without destroying laminar flow conditions therein. Instead of the relatively long single nozzle of the prior art there is provided a plurality of nozzles expanding in three dimensional directions and arranged in parallel aligned relationship in a cluster closely adjacent each other. The nozzles may be of many cross-sectional shapes but in one embodiment the walls are concave, such that a relatively large wall angle with respect to the direction of flow at the throat of the nozzle diminishes progressively toward the end of the nozzle so that at such end the nozzle walls will be substantially parallel with each other, whereby to discharge the gas stream therefrom in a jet of constant cross-sectional area.