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: 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: Apparatus and method for producing coherent secondary x-rays that are controlled as to direction by illuminating a mixture of high z and low z gases with an intense burst of primary x-rays. The primary x-rays are produced with a laser activated plasma, and these x-rays strip off the electrons of the high z atoms in the lasing medium, while the low z atoms retain their electrons. The neutral atoms transfer electrons to highly excited states of the highly striped high z ions giving an inverted population which produces the desired coherent x-rays. In one embodiment, a laser, light beam provides a laser spark that produces the intense burst of coherent x-rays that illuminates the mixture of high z and low z gases, whereby the high z atoms are stripped while the low z ones are not, giving the desired mixture of highly ionized and neutral atoms.

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

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: 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: 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: 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: 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: Bi-stable image storage apparatus for storing, interrogating, and erasing two-dimensional binary images represented by arrays of light and dark areas. The storage apparatus comprises a pair of image amplifiers, preferably, inverting amplifiers, coupled together into a closed loop optical circuit such that the output of one device will be read into the other device. As long as the gain of the circuit is greater than one the circuit will drive itself to saturation and store an image optically applied thereon. The system provides a very inexpensive circuit for storing images, and can be used in a wide variety of processing and display applications.

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: 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: A tunable laser is disclosed in which a plurality of laser beams different from one another in wavelength and polarization can be simultaneously oscillated. The tunable laser is advantageous among others in that an atomic absorption spectroscopic analysis can be carried out with very high sensitivity when it is used as, for example, a light source for two-wavelength measurement in the atomic absorption spectroscopic analysis.

Abstract: A laser gyroscope is disclosed wherein two pairs of waves propagating in opposite directions in a laser resonator are amplified by the laser medium of such resonator. The frequencies of such waves, which are all different, are maintained symmetrically about the center maximum gain frequency curve associated with the laser medium by operation of a pathlength stabilizer. Means are provided for combining a portion of each one of the waves in at least one of the pair of waves into a single composite beam and for controlling, in accordance with the relative levels of the energy in the components of such single composite beam, the pathlength of the laser resonator. With such an arrangement only one photodetector is required for pathlength stabilization.

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: 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: An on-line system for continuously monitoring the color, opacity and brightness of a moving web of paper or the like in which an optical shoe providing black and white backgrounds spaced in the direction of movement of the web supports a portion of the web below and generally in registry with an optical head made up of a light integrating sphere for directing light from a source onto the web over the shoe and a plurality of elongated sensing units mounted in the upper portion of the sphere and including a centrally located brightness measuring unit oriented generally perpendicularly to the web toward a point over the black background, four circumferentially spaced color tristimulus sensing units, each of which is oriented at an angle to the axis of the central unit so as to be directed at the same point as is that unit and a sixth opacity sensing unit angularly oriented with respect to the axis of the central unit so as to be directed toward a point over the white background spaced downstream of the first poi

Abstract: A dye laser, pumped by a nitrogen laser, has been made to operate in both the TE.sub.01 and TM.sub.01 rotationally symmetric modes, regardless of the variation in laser wavelength. By changing the spacing of lenses within the optical cavity, the single laser can be made to switch from the TE.sub.01 mode to the TM.sub.01 mode and back again to the TE.sub.01 mode.

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: 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.