Abstract: An optical mirror having coolant means for compensating thermal tilt of the reflective surface is disclosed. The optical mirror has a laminated structure formed of a plurality of plates including a faceplate, a second plate, a third plate, a substrate plate and a back plate each having coolant means therein for passing a coolant therethrough. The plurality of plates are bonded together to form the laminated structure. Each of a plurality of first coolant channels disposed within the faceplate have a substantially parallel relationship with one another and a substantially vertical, parallel relationship with each of a plurality of second coolant channels disposed within the second plate.

Abstract: An apparatus and method for minimizing gas density perturbation within an optical region of a gas dynamic laser to improve the optical quality of the output laser is disclosed. Gas disturbance generators disposed intermediate the throat region of the nozzle and the optical region are adapted for producing a disturbance to the flow to oppose flow density disturbances resulting from shock or expansion waves emanating from the intersection of the ends of the nozzle and side walls. In one embodiment the gas disturbance generator is a protrusion into the gas path. A further embodiment utilizes a jet of gas into the gas path to produce the disturbance. A further embodiment utilizes suction along the side wall to produce the disturbance. The optical quality of the laser energy passing across the gas flow is significantly improved.

Abstract: A cryopump having a cryopanel adapted for being cooled by a first refrigerant and shielded from radiation incident thereon by shields adapted for being cooled with a second refrigerant is disclosed. The cryopanel and the radiation shield are fabricated with a first material having high thermal conductivity, such as aluminum, while means for distributing refrigerant from refrigerant dewars to the cryopanel and shields are made of a second material, such as stainless steel. The stainless steel and aluminum sections are connected by an aluminum-steel transition connector adapted for providing vacuum tight connections at cryogenic temperatures. Both the cryopanel and chevrons comprising the shields are fabricated and extruded aluminum with coolant passages formed therein. Thermal distortions during operation are compensated by the use of stainless steel bellows within refrigerant distribution lines.

Abstract: A high power gas dynamic mixing laser capable of having an energizing gas formed by an exothermic decomposition process is disclosed. The laser includes a housing having a reaction chamber in which an excitation gas is formed by thermal decomposition of a starting material, a nozzle connected to the housing for expanding the excitation gas to supersonic velocity, means for injecting a lasing gas into the supersonic stream of excitation gas to produce an inversion of populated energy levels of the lasing gas, optical means for extracting a laser beam and exhaust means for passing the gas mixture to the atmosphere. An embodiment of the present invention includes a return duct attached at one end to the exhaust means and at the other end to the housing for circulating the gas through the laser and a lasing gas capable of thermal decomposition downstream the optical means to form the excitation gas.

Abstract: A closed cycle chemical laser adapted for continuous wave operation is disclosed. A first gas such as sulphur hexafluoride is decomposed by an electrical discharge means to provide at least some fluorine atoms which when combined with molecular hydrogen in a mixing chamber located upstream of and proximate to an optical power extraction chamber forms an excited laser species capable of stimulated emission to produce a continuous wave output beam. After passing through the optical cavity the effluent is purified by selective absorption and adsorption processes to eliminate the laser species from the effluent and to separate the hydrogen for recirculation back to the mixing chamber. The remaining effluent has its pressure increased, is supplemented with makeup feed gases and is recycled. The operation of the system using sulphur hexafluoride and hydrogen gases is discussed in detail and various combinations of other suitable reactants are disclosed.

Abstract: An apparatus adapted for providing an aerodynamic window having a cylindrical configuration with an annular cross section capable of enveloping annularly a cavity therein is disclosed. The apparatus includes an annular injector adapted for providing a flow of first gas therefrom through a gas path having an annular cross section, an annular collector disposed in a spaced apart relation with the annular injector and adapted for collecting gas flowing through the gas path wherein the annular collector, the annular injector and the gas path cooperate to enclose a cavity therebetween and a gas insertion means for providing a flow of second gas within the cavity. In one embodiment electrodes disposed within the cavity are adapted for enhancing the energy level of the recipient elements of the second gas, as for example by ionization, to produce a high intensity light source.

Abstract: An optically pumped laser system having a configuration capable of efficiently coupling pumping radiation with a gain medium to provide an outlet beam having a wavelength in the ultraviolet and visible spectrum is disclosed. A gain medium including halide, rare and noble gas elements is contained within a cell at total pressures from four to thirty atmospheres. The gain medium is ionized by a spark source within the cell and interacted with optical pumping radiation to provide a diffuse electrical discharge. An optical resonator having the discharge disposed therein efficiently extracts energy from the gain medium to provide an output beam having a wavelength in the visible spectrum when the total pressure of the gain medium is high, typically greater than nine atmospheres and a wavelength in the ultraviolet spectrum when the pressure is moderate, typically less than five atmospheres.

Abstract: A pressure balancing fluid transfer manifold for use with fluid cooled laser mirrors is disclosed. The manifold is adapted for connection to the inlet and outlet ports of a fluid cooled laser mirror and includes an interface fitting adapted for being fixedly connected to a mounting plate which supports the laser mirror and a housing fixedly attached to the mirror wherein the interface fitting is sealably engaged within the housing with O-ring type seals. Elongated slots within the walls of the fitting are adapted for passing coolant from the fitting to the mirror coolant distribution system. Hydraulic pressures within the fitting are decoupled from the mirrors by a vented cavity located between the end of the fitting and the mirror and the pressure forces are transmitted through the fitting to the mounting plate thereby minimizing distortion of the mirror resulting from unbalanced pressure forces. In one embodiment the interface fitting is coupled directly to the coolant distribution system within the mirror.

Abstract: A method for cavity dumping a Q-switched laser having a gaseous gain medium to obtain submicrosecond output pulses, typically controllably variable between ten and three hundred nanoseconds at a high pulse repetition frequency typically up to at least twenty-five thousand pulses per second is disclosed. In a laser adapted for continuous wave operation, a combination of a retardation element and an electrooptic modulator provides a first polarization state to intracavity radiation incident onto an intracavity polarization coupler oriented to couple out of the cavity radiation having the first polarization state to provide a high loss condition to the cavity to maintain the laser below threshold. A voltage applied quickly to the modulator converts the first polarization state to a second polarization state to provide a low loss condition to the cavity to Q-switch the laser.

Abstract: A laser having a gaseous gain medium capable of continuous wave operation and including an etalon with a Stark active gas disposed therein, adapted for providing submicrosecond pulses is disclosed. A method of utilizing the Stark effect to tune rapidly an etalon to form an output mirror having a variable reflectivity to Q-switch and cavity dump the optical flux within a laser to provide an output pulse of laser radiation having a submicrosecond pulse width, typically variable between fifty and three hundred fifty nanoseconds, at a pulse repetition frequency up to twenty-five kilohertz is disclosed. A laser typically having a carbon dioxide gain medium adapted for continuous wave operation includes a grating defining one end of the laser resonator and an output mirror defining the other end wherein the output mirror is an etalon formed with two mirrors containing a switching cell having a Stark active gas disposed therein.

Abstract: A method of separating isotopes of hydrogen utilizing isotopically selective photodissociation of organic acid is disclosed. Specifically acetic or formic acid containing compounds of deuterated and hydrogenated acid is irradiated by radiation having a wavelength in the infrared spectrum between 9.2 to 10.8 microns to produce deuterium hydroxide and deuterium hydride respectively. Maintaining the acid at an elevated temperature significantly improves the yield of isotope separation.

Abstract: A resonator is disclosed having a mode control cavity and a power extraction cavity capable of being independently optimized to produce a laser beam having high power and good optical quality in the far field. The mode control cavity is a positive branch confocal unstable resonator having large geometric magnification and a low Fresnel number to provide mode discrimination against higher order radial and azimuthal modes such that the lowest loss mode, typically the lowest order fundamental mode is strongly favored. The power extraction cavity is adapted to accommodate a gain medium having a large volume. A first cone adapted to provide line of sight communication between the mode control cavity and the power extraction cavity optically couples the cavities and provides means for varying the diameter of radiation passing between the mode control cavity and the power extraction cavity.

Abstract: A variable output resonator is disclosed having a mode control cavity and a power extraction cavity both capable of being independently optimized to produce a laser beam having high power and good optical quality in the far field. A cone having a conical reflective surface is adapted to be linearly moved along a beam axis of the power extraction cavity in the resonator to intercept a portion of the radiation circulating therein to produce the laser beam. Both the diameter and power level of the laser beam are dependent upon the area of the reflective surface of the cone which interacts with the radiation circulating within the resonator. The insertion of the cone into the resonator does not influence the overall resonator alignment since the cone is external to the optical components defining the resonator.

Abstract: An improved laser gain tube for use in a differential laser gyro is disclosed. The gain tube comprises a housing having a cathode located therein with a pair of chambers located within the cathode, a pair of discharge tubes extending from anode regions on each side of the cathode into each of the chambers and means for providing an electrical discharge within the chambers. An aperture positioned between the chambers is adapted to provide optical communication therebetween while maintaining electrical isolation of an electrical discharge in each chamber. The chamber walls are adapted for maintaining the discharge with a current density below the threshold for cathode sputtering.

Abstract: An improved spatial filter for operation with high power laser beams is provided wherein a first gas flow system and a second gas flow system cooperate to enclose a cavity therebetween capable of accommodating a filter having an aperture located therein for spatially filtering the beam. The first and second gas flow systems are adapted for providing a first aerodynamic window across a beam entrance and a second aerodynamic window across a beam exit to maintain a selected gas pressure within the cavity while providing a transmission path for a high power laser beam. The first and second aerodynamic windows are in optical line of sight communication with one another through the aperture in the filter.

Abstract: A method of material processing, in particular welding, utilizing high frequency interruption of a continuous wave beam of radiation is disclosed. The pulses of laser radiation are generated at a pulse repetition rate more rapid than the thermal response time of the material, typically greater than one kilohertz, wherein the material reacts with the pulses such that the characteristics of the surface reflectivity of the material are dominated by the peak power in the pulse and the characteristics of the melting of the material are controlled by the average power of the pulses. The duration of each pulse is controlled to be less than the time required to generate a beam absorbing plasma adjacent the weld zone. The absence of beam absorbing plasma and the efficient destruction of the reflectivity of the surface of the material results in increased welding efficiency and/or increased welding speed.

Abstract: An unstable ring resonator capable of providing an output beam having high power and high optical quality is disclosed. The unstable ring resonator is formed with a first region capable of providing transverse mode discrimination, beam magnification and improved beam quality, a second region capable of accommodating a gain medium and means for out coupling a beam of electromagnetic radiation to provide an output beam. Transverse mode discrimination is provided by the lowest loss mode characteristic of unstable resonators, improved mode discrimination and optical quality is obtained by utilizing mirrors having curved surfaces to focus the circulating electromagnetic radiation through spatial filters having line apertures and beam magnification is provided by the relative spacing of the curved surfaces.