Abstract: Electron beam generator and the applying of such a generator to a gas laser head comprising, more particularly, an anode and a cathode arranged in an enclosure under low pressure; it comprises, moreover, a device for lighting up the cathode by ultra-violet radiation. The generator can be applied to the ionizing of the gaseous mixture of a gas laser generator.

Abstract: This invention concerns a traveling wave amplifier of pillbox configuration hat can be made for battery operation. It has a high perveance cylindrical electron gun between closely spaced, parallel, flat surfaces of a pair of thin ceramic disks sealed at their perimeters to a conductive collector ring coaxial with the electron gun. One or both of the disks support a novel planar slow wave circuit. The slow wave circuit is termed a ring-bar circuit but differs from cylindrical ring-bar structures. It includes a series of concentric conductive rings. Along one diameter of the rings, to one side of the center of the rings, the first and second, third and fourth, fifth and sixth rings, etc., are conductively connected, and to the other side of the center of the rings, the second and third, fourth and fifth, sixth and seventh rings, etc., are conductively connected.

Abstract: An ultra wide band traveling wave tube amplifier is disclosed. The amplifier employs a helix derived slow wave circuit arranged for electromagnetic interaction with a beam of electrons passable axially through the helix circuit. Signals to be amplified within the passband of the circuit interact with the electron stream to produce an amplified output signal which is extracted from the helix and coupled to a suitable utilization device. The bandwidth of the traveling wave tube amplifier is substantially increased by the provision of a conductive circuit loading structure disposed surrounding the helix circuit and extending for at least half of its length and preferably for substantially its entire length.

Abstract: Helium in the superfluid state has been found to emit copious amounts of radiation in the ultra-violet region when excited by an electron stream. Conventional laser action using mirrors is impossible in superfluid helium because there are no mirrors that will reflect VUV radiation. By utilizing the well known method of "distributed feedback" the superfluid helium can be made to lase. By setting up a standing wave in superfluid helium that has a wavelength equal to, or harmonically related to, half the wavelength of the photon radiation chosen to be emitted as laser radiation by the superfluid helium, the need for end mirrors to produce reflection of the laser radiation is eliminated and reflection occurs instead at the wavefronts of the standing wave. The photons leave the superfluid helium at right angles to the standing wave as coherent radiation having a very high intensity.

Abstract: A high power, cw, high pressure, electrically excited flowing gas laser is disclosed wherein a laser excitation transverse to the direction of gas flow is initiated by a uniform electron beam perpendicular to the gas flow direction. Laser gas supplied to a plenum chamber at a pressure substantially greater than atmospheric pressure is conditioned by a perforated plate nozzle to flow through the laser cavity in a uniform stream at the desired subsonic velocity. A variable angle diffuser is provided downstream from the laser cavity to decelerate and compress the laser gas before exhausting it into the ambient atmosphere such that at the downstream end of the laser excitation region the laser gas is maintained at a pressure slightly lower than atmospheric pressure.

Abstract: A gas dynamic-transfer chemical laser is formed by burning a halogenated and deuterated tetrazole and expanding the combustion products through a supersonic nozzle and injecting into the expanding products, a secondary stream of cold D.sub.2 or cold H.sub.2.

Abstract: A diode discharge device may include a tubular anode concentrically encircled by and spaced from a tubular cathode electrode with ends intermediate the ends of said anode electrode, and a metal conductive housing having a tubular wall disposed around the cathode electrode with end walls connected to the anode electrode. High energy electron current coupling is through an opening in the housing tubular wall to a portion of the cathode electrode intermediate its ends. Suitable utilization means may be within the anode electrode at positions to be irradiated by electrons emitted from the cathode electrode and transmitted through the anode walls.

Abstract: A gas laser including a discharge tube containing a gas mixture, the discharge tube having one or more inlets and an outlet, in which a reaction vessel is in communication with said outlet and with the inlet of a vacuum pump, and in which the outlet of the vacuum pump is in communication with the or each inlet of the discharge tube.

Abstract: Broadly tunable infrared lasers analogous to dye lasers operating in the visible spectrum are provided by significant improvements upon an F.sub.A (II) color center laser previously demonstrated in a limited way. The improvements include techniques for also using F.sub.B (II) and F.sub.2 .sup.+ color centers and include substantially increased concentrations of the F-centers in regions of pumpable geometry, judicious choice of pumping frequencies and powers and variable, frequency-selecting resonators that are capable of producing oscillation anywhere in the color center fluorescence bands. All solid-state cooling by means of contact between the crystal and a solid heat sink is provided in a way that provides the optical quality needed for efficient operation and for greatest tuning bandwidth of the laser. Use of the color centers in distributed feedback devices is described.

Abstract: A regenerative laser device having remotely located optical components. A resonant cavity having a plurality of transverse modes is defined at one end by a highly reflective retrodirective member and at the other end by a retrodirective member formed of a converging lens and a highly transmissive mirror. A body of laser material is located within the resonant cavity, and there are provided means for exciting the material to create a loop gain of the device that is substantially equal to unity. A collimating lens receives light transmitted through the mirror. An energy source supplies additional energy into the resonant cavity through the collimating lens and mirror to increase the radiation, in at least one of the transverse modes, in the resonant cavity.

Abstract: An optical cavity for a flash lamp pumped dye laser including a pumping cavity, a birefringent filter and a plurality of frequency doubling crystals. Within the pumping cavity the flash lamp is cooled by forced air convection and operated with a D.C. simmer current. Simultaneously, the dye carrying conduit within the pumping cavity is cooled with water. The operating life of the dye is increased by using selectable filters to remove the ultraviolet radiation eminating from the flash lamp before it falls on the dye. The construction of the pumping cavity permits changing the flash lamp and the dye conduit without disturbing the optical path of the laser.

Abstract: Non-return optical Faraday device comprising plates made of a material having a Verdet constant, placed in a magnetic field and acting, simultaneously, as a polarizer, an analyzer and a rotator.

Abstract: A laser cavity electron beam injection device provided with a single elongated slit window for passing a suitably shaped electron beam and means for varying the current density of the injected electron beam.

Abstract: A high power, cw, high pressure, electrically excited flowing gas laser is disclosed wherein a laser excitation transverse to the direction of gas flow is initiated by an electron beam perpendicular to the gas flow direction. The electron beam has a cross-sectional area conforming substantially to that of the excitation region and is especially profiled to have a cross-sectional electron density which varies as a function of distance along the direction of gas flow from substantially a minimum value at the upstream and downstream extremities of the excitation region to a maximum value approximately midway along the excitation region. This profiling, which may be achieved by tapered width apertures in either an electron beam window support member or in an electron gun grid, provides an appropriate heat input to the laser gas to minimize gas density variations in the excitation region and thereby optimize the beam quality of the generated laser beam.

Abstract: A chain reaction laser system which operates with two species lasing simultaneously is disclosed. The laser is combustion-driven and provides an output of continuous wave radiation. A fluorine interhalogen and atomic fluorine are mixed together with hydrogen to induce chemical reactions which provide two species of hydrogen halides which are vibrationally excited as well as atomic hydrogen and atomic fluorine. The latter, atomic fluorine, is then available to react with additional hydrogen in a chain reaction sequence. The various preferred reactants and two preferred structures are discussed. In a first embodiment the fluorine interhalogen and atomic fluorine which are both essential to the operation of the invention are both formed as they are needed in a reaction region at relatively high temperature and pressure. In a second embodiment one reactant is formed under conditions of relatively high temperature and pressure and the other at low temperature and pressure conditions.

Abstract: In a laser system, the method of operating a laser simultaneously as an oscillator to produce a beam of coherent light and as an amplifier for backscattered light from targets illuminated by the coherent light in such beam is disclosed.

Abstract: A semiconductor is positioned as the anode of an electron tube, and is borded with a radio-frequency modulated stream of electrons. This bombardment produces carrier pairs in the semiconductor in a well known manner. However, in this case the carrier pairs are bunched, in the same manner as the modulating electrons, as they are drawn through the semiconductor by its bias voltage. A radio-frequency coil or meander line adjacent to the semiconductor interacts with the bunched carrier pairs traveling through the semiconductor -- in the same manner as the radiofrequency coil of a traveling wave tube interacts with the electrons of a traveling wave tube, as they become bunched -- to produce an amplified r-f signal in the coil.

Abstract: An improved apparatus and technique for providing tunable high power millimeter and submillimeter radiation. A tunable source of microwave energy is coupled to an evacuated drift tube in which an intense relativistic electron beam is propagated while constrained in a magnetic field having a direction parallel to the direction of the electron beam. The microwave energy is directed in a direction opposite to the direction of the electron beam to generate millimeter or submillimeter radiation by backscattering from the intense relativistic electron beam. By tuning the frequency of the microwave energy to be mismatched by a specific amount from the electron cyclotron frequency in the rest frame of the electrons at high beam currents, a coherent scattering of microwave energy from electron bunches will produce enhanced power output of millimeter and submillimeter radiation.

Abstract: A plurality of thermionic filaments are arranged in side-by-side relationship. A spreader electrode which may be in the form of a flat plate is placed on one side of the filaments, while an anode is placed on the other side of the filaments, with a grid being interposed between the filaments and the anode. The various aforementioned elements are given dimensions and positioned relative to each other and the voltages thereon adjusted so as to shape the trajectory of the electrons to provide a uniform distribution of electrons at the anode with a minimum dissipation of energy in the grid and spreader electrodes.

Abstract: An electrode switch arrangement for producing a fast-rise, long-path-length, uniform electron beam for short wavelength laser pumping.

Abstract: A laser system and method for exciting lasing action in a molecular gas lasing medium which includes cooling the lasing medium to a temperature below about 150 K and injecting fission fragments through the lasing medium so as to preferentially excite low lying vibrational levels of the medium and to cause population inversions therein. The cooled gas lasing medium should have a mass areal density of about 5 .times. 10.sup.-.sup.3 grams/square centimeter, relaxation times of greater than 50 microseconds, and a broad range of excitable vibrational levels which are excitable by molecular collisions.

Abstract: Low frequency noise in a gas laser is suppressed by providing an auxiliary cathode in proximity to the anode to provide an auxiliary gas discharge between these elements. The anode and another cathode provide a primary gas discharge for lasing operation.

Abstract: An optical amplifier particularly for use in a high data-rate fibre-optics communication link utilizing a body of a dielectric substance transparent to signal light of a given band of wavelengths and transparent also to pumping light of a different band of wavelengths, a smooth continuous surface along the length of the body having as amplifying component a layer of laser material adhered contiguous to the surface. Both signal light and pumping light are introduced into an end face of the body, which may be a passive dielectric fibre core such as glass, or a passive dielectric slab with parallel side walls, utilising mode order converting holograms. By the phenomenon of penetration by light of both frequencies within a thin layer of the adhered material as the light beams undergo multiple total internal reflections at the interface between the body and the laser material, atoms of active material, e.g. Nd.sup..sup.

Abstract: A laser heterodyne system is disclosed wherein received reflections of a beam of coherent light are amplified in a laser. The amplified received reflections are heterodyned with the light produced by the laser and the resulting beat frequency is detected using a photodetector. A controller, responsive to the beat frequency, controls, in one case, the frequency of a transmitting laser, and hence the frequency of the received light, and, in another case, the frequency of the light produced by the amplifying laser so that, in either case, the difference between the frequency of the received light and the frequency of the light produced by the amplifying laser is adjusted to maximize the amplification of the received light by the amlifying laser prior to detection by the photodetector.

Abstract: An intermediate amplifier for a transmission system intended for communications transmission applications using light waves in optical wave guides employs an optical amplifier for amplifying the light waves on the laser principle, wherein an optical filter is provided to restrict the frequency band of the optical amplifier to the frequency band of the pulses being transmitted. The filter comprises a dielectric multi-layer system arranged upon an inclined surface of the optical amplifier through which the signal light passes in one embodiment. In another embodiment the filter is a zone of the output wave guide of the amplifier which has an absorption characteristic outside of the frequency band of the light pulses which are to be transmitted.

Abstract: An aerodynamic window for isolating different gases or different states of ases when typical transparent window material is not feasible. An adjustable, supersonic conical nozzle is mounted coaxially with an opening and a cylindrical tube is mounted to the opening and extends coaxially toward the conical nozzle. A sliding-wedge-type gate valve is used to close the tube. The start up procedure consists of adjusting the conical nozzle axially to equalize the pressure on both sides of the wedge valve. Once the pressure is equalized the wedge may be removed.

Abstract: New lasers employ a halide crystal including alkali metals and rare earths with a very high concentration of the active ions that are arranged to have largest possible separation between themselves. Such laser crystals provide very high energy storage that is finally released in the form of optical radiation. The high energy storage is attributable to a relatively low gain per unit length. The halide crystal is of the perovskite type and typically includes two alkali metals, one of which, for example, sodium, has a much smaller ionic charge than the rare earths and, therefore, will be ordered on the octahedral sites of the perovskite crystal with respect to the rare earth atoms. The stoichiometry of the materials facilitates the high concentration of the rare earth active ions; and the ordering or strict sequencing of alkali and rare earth ions facilitates the large separation of the rare earth active ions which is necessary to minimize non-radiative decay via rare earth pair interaction.

Abstract: An optical intermediate amplifier intended for a system of communications transmission by means of light waves through optical wave guides employs an optical amplifier for amplifying the light waves on the laser principle. The amplifier is provided with rectangular cross sectional areas traversed by the light waves which correspond in size with the cross-sectional areas of the core zones of the wave guides with which the amplifier is serially coupled, the rectangular cross sectional areas having heights of 0.1 to 10 .mu.m and widths of 100 to 300 .mu.m.

Abstract: To prevent deleterious effects from the sputtering of the cathode of a laser, the cathode surface portions exposed to the gaseous filling within the laser envelope are coated with a vaporizable metal. The coated cathode surface portions are held during laser operation at a temperature within a small range of values including the vaporization temperature of the metal coating the cathode surface. The atoms of the coating metal are sputtered off of the cathode surface by ion bombardment during operation but are immediately redeposited from the vapor of the coating metal adjacent to the cathode surface. Cataphoretic containment of the metal vapor within the central portion of the laser envelope is obtained by providing access to the cathode electrode from an anode electrode in each end of the envelope only through insulating tubular members having a length-to-inner diameter ratio greater than 2 and optimally around 5.

Abstract: A high power density continuous wave (c. w.) gas dynamic laser system is described which includes a non-equilibrium plasma jet for generating excited gaseous species having high vibrational temperature and low gas temperature. Gas flow through the plasma jet is reduced to highly turbulent subsonic flow by an expanding nozzle. Lasing in an optical cavity oriented transversely with resspect to the flow of the gaseous plasma extracts vibrational energy from the excited gaseous species as the emerge from the expansion nozzle.The described system also includes, immediately upstream from the optical cavity, an injection system which introduces and uniformly mixes a lasing gaseous species into the highly turbulent subsonic gaseous plasma flow from the plasma jet. Gas sweeps are established in the arms of the optical cavity to cool and sweep high temperature unexcited gas species therefrom in order to reduce absorption in the optical cavity.

Abstract: A Nernst lamp is used as the pumping means for a solid state laser. The l materials are selected so that the light energy emitted is essentially concentrated in the relatively narrow pump region of the absorption spectrum of the laser crystal. The input power in to the laser is equivalent to that of much higher power lamps operating over a much wider spectrum.

Abstract: A laser amplifier system having plural parallel paths for amplification of laser radiation from a single, stable laser oscillator. The plural paths of laser amplification are excited to produce sequential pulses of amplified output radiation that are interleaved by an optical combining system to produce a single path of amplified, pulsed radiation of increased repetition rate.

Abstract: A laser system for producing short optical pulses with higher energy and controllable shape from a high power solid state laser system. The system includes two gratings at the output with an adjustable interferometer between the laser source and an amplifier element. Thus, the output pulse may be tailored to a particular shape.

Abstract: Light that is initiated in a laser device includes a diffusion of scattered and reflected light around the laser beam. This diffusion of light occurs because light in the optical cavity of the laser is reflected from the surfaces of the bore and becomes misaligned, so that it leaves the laser along paths which are outside of the cone of light formed by the laser device. This diffusion of part of the laser light reduces the efficiency of the device and is objectionable in many applications. The diffused light is eliminated by providing a restriction in the optical cavity of the laser device which blocks off the stray or misaligned light. This restriction, or beam cleaner, may be positioned at various points along the axis of the optical cavity.

Abstract: An optical power amplifier system for extracting high power radiation from a basic active laser media. The system includes a plurality of basically confocal mirrors so positioned that radiation output from a laser is amplified, that no power is absorbed in the supporting structure and it has no feedback from the secondary mirror. In the system, the laser beam passes through the active laser media region at least four times which increases the output power.

Abstract: In the present application there is disclosed an improvement in the operation of transverse energization systems for atmospheric pressure CO.sub.2 lasers using a plasma forming plate in which a subsidiary or auxiliary spark gap is provided between one end of the cathode bus bar and the plasma forming plate. Most of the current for the main discharge thus passes through this subsidiary spark gap, and small glow discharges rather than arcs occur between the tips of the cathode pins and the edges of the holes in the plasma forming plate. The use of elongated slots in the plasma forming plate and the use of a mesh in place of the discrete slots is also disclosed. The results of experiments conducted utilizing apparatus of the prior art and of the present invention are also included.

Abstract: Method and apparatus are described for reducing amplifier distortion by establishing a first signal at a first frequency to be amplified in an amplifier which while amplifying the first signal produces a second undesired signal at another frequency, producing on a cycle by cycle basis of the first signal a third signal at the other frequency, adjusting by no more than substantially 180.degree. the relative phase and amplitude of the first and third signals for mutual cancellation of the second and third signals and then amplifying the first signal in the amplifier and reducing the power of signals at the other frequency relative to the power of the amplifier signal at the first frequency. Examples are given where the second signal is a harmonic or an intermodulation frequency signal of the first signal.

Abstract: A laser gyro is disclosed having a long life cathode located therein. The laser gyro comprises a block having a plurality of lasing tubes bored therethrough and being angularly disposed to each other to form a closed path within the block. A plurality of mirrors are positioned at the intersection of the tubes to reflect light from one tube into the next. A pair of anodes are inserted into two of the lasing tubes. A cavity is formed within the center of the block and is connected to the triangular laser path via a conduit. The cavity contains a cathode for conducting direct current to each of the anodes. These current flows energize the lasing gas to create a pair of laser beams moving in opposite directions in the closed path. The cathode is a closed end, hollow cylinder made of aluminum having a layer of oxide formed thereon by means of anodization.

Abstract: A method and means are disclosed for obtaining high pulse rate metal vapor laser transitions by vaporizing a metal halide of the desired metal. The vapor of the metal halide is transversely passed at at least sonic velocities through a discharge region where it is dissociated to provide a neutral metal atom excited to an upper laser level by electrons of sufficient energy to create resonance radiation trapping and a population inversion of the upper laser level. The flow rate is maintained to permit the excited metal atom to emit laser radiation by stimulated emission to a lower laser level in the discharge region and to remove the lower laser level atoms therefrom. Dissociation and excitation of the flowing metal atoms are repeated periodically.

Abstract: The body current of a TWT (traveling wave tube) is measured by generating a voltage that is proportional to the difference between the cathode and collector currents of the TWT without materially affecting either by passing the cathode and collector currents through separate transformer windings, wound in opposition, on both a linear core transformer and a nonlinear core transformer with separate windings coupling each transformer to the other. A voltage pulse is introduced into another winding on the nonlinear transformer causing a current flow in the circuit coupling the two transformers, the voltage magnitude of which is proportional to the difference between the cathode and collector currents which is the body current.

Abstract: Cold cathode gas lasers where the cathode of the circuit exciting the discharge, is an aluminium tube which forms an integral part of the sealed envelope of the laser.Such a structure can be used in lasers whether coaxial or otherwise. It makes it possible to improve their performance characteristics and to reduce their cost.

Abstract: Gas laser comprising a flat electric energizing line consisting of an insulating layer inserted between two metallic layers brought to different potentials, one of whose edges is cut out in the shape of a parabola, one slot being provided in one of the layers, an active gaseous medium flowing in the slot, a circuit for setting up a substantially punctiform discharge between the metallic layers at the level of the focus of the parabolas. The electric line is arranged on a massive plate comprising on the one hand a cut provided in its lower face substantially opposite the slot and communicating with the latter and on the other hand two grooves provided on its upper face each having fitted in it a flexible seal and arranged opposite the walls of the slot.

Abstract: A molecular gas laser capable of operating at or near atmospheric pressure in which electrical energy is coupled into an active molecular gas medium comprising molecules having vibrational rotational energy levels by means of an electric field transverse to the lasing axis. By applying an impulse voltage to the electrode configuration, high current glow discharges can be created. The pulse discharge takes place between electrodes having parallel planar surfaces facing each other. The lateral edges of these faces are suitably profiled to avoid field concentrations and thus provide a diffused glow discharge in a uniform electric field transverse to the lasing axis. Initiatory electrons required to produce the high current diffused glow are provided by generating an intense burst of corona in the gap between spacer members having very high dielectric constants which are interposed between the electrodes.

Abstract: A single electrooptic crystalline material, having a first pair of electrodes affixed thereto along opposite faces, and a second set of electrodes affixed to alternate opposite faces, is disposed within a laser cavity. The orientation of the crystal and selection of electrode faces is such that the application of two different electric fields can achieve simultaneous mode-locking of the laser with output coupling of the optical pulses.

Abstract: The invention is directed to a method for obtaining pulsed metal vapor laser transitions. The method comprises placing a metal halide of the desired metal within an enclosure and vaporizing the metal halide to provide a metal halide vapor. The metal halide vapor is thereafter dissociated to provide ground state metal atoms of sufficient number density to create a condition for resonance trapping and, substantially simultaneously therewith, ground state metal atoms are excited to an upper laser level, while maintaining a sufficient number in the ground state to preserve said resonance radiation trapping condition, with electrons sufficiently energized to create a population inversion between the upper and lower laser level. The excited metal atom is permitted to emit laser radiation by stimulated emission to a lower laser level and the emission is resonated, preferably between a pair of externally mounted mirrors.

Abstract: A laser featuring, in one aspect, a volume of gas having a lasing constituent, a light source arranged to emit light having ionizing photons for ionizing the gas, the effective photon energy spectrum of the ionizing photons lying below the ionization potential of the lasing constituent and below the level of photon absorption bands of the gas, the spectrum being selected to provide an average penetration depth of the ionizing photons into the gas of at least 1 cm. and to photoionize the gas predominantly by a multiple step process involving absorption of successive photons at least the first of which has a photon energy less than the ionization potential of said lasing constituent, and an electric field source for applying to the gas a voltage sufficient to produce an avalanche breakdown in the gas to effectively raise the lasing constituent to its lasing level; and in another aspect a seed gas comprising an amine having the structure ##EQU1## where R.sub.1, R.sub.2, and R.sub.

Abstract: The noise in a crossed field amplifier output is reduced by providing a non-uniform magnetic field across the surface of the cathode. This may be achieved by providing a curved magnetic field across the cathode or by providing a concave shaped cathode. Additionally the cathode may be tilted with respect to the cross magnetic field.

Abstract: The cell of a liquid laser is defined between the rounded, parallel edges four coaxial cylinder sectors of fused quartz. The narrow gaps circumferentially bounded by the flat, converging side faces of the sectors provide conduits for rapid flow of dye liquid into and out of the cell which extend over the full axial length of the cell. The light of a flash tube is directed toward the cell through the cylindrically arcuate outer face of each sector.

Abstract: A fluid-filled amplifier cell for laser generation comprises an elongated housing wherein at least one end contains, within the cell, a window supported at the Brewster angle and wherein such end is plugged with a mirror.

Abstract: A circuit is provided in a traveling-wave tube package which eliminates the need of manually setting the power supply voltage to match the proper operating voltage of the tube. The circuit utilized within the traveling-wave tube package forms a part of the power supply, the remainder of which is provided externally of the traveling-wave tube package. By selecting the proper circuit components, the traveling-wave tube package can be connected without adjustment to a power supply and still operates at the desired voltage.