Abstract: A laser device has a plurality of electrodes mounted on an electric discharge tube and high-frequency power supplies connected respectively to the electrodes. The laser device comprises output detecting means (6, 7) for detecting output conditions of the high-frequency power supplies, respectively, fault detecting means (1b) for detecting the failure of a high-frequency power supply from the output conditions detected by the output detecting means (6, 7), and on/off switching means (1a) for turning off the failing high-frequency power supply in response to a failure signal from the fault detecting means (1b). When one of the high-frequency power supplies (21) fails, its output is cut off, and the operation of the laser device is continued by the remaining normal high-frequency power supplies.

Abstract: Generation of monochromatic coherent electromagnetic radiation by application of Bose-Einstein condensation of electromagnetic radiation which is achieved by causing a sufficiently large, overcritical mean energy density of electromagnetic radiation in a suitable cavity for electromagnetic radiation.

Abstract: A method for creating population inversions for use in stimulated emission devices which beam combine, beam clean-up, or frequency up-convert electromagnetic radiation. The invention comprises near resonantly enhanced multiphoton pumping of a multilevel quantum medium with pump beams of appropriate intensities and frequencies detuned from the transition frequencies of the medium. The intensities are orders of magnitude lower than those required for non-resonantly enhanced multiphoton pumping. The detuning is smaller for the maximum multiphoton resonance than for the single photon resonances. Appropriate medium decay constants are required for creating a population inversion between energy levels of the quantum medium. The population inversion exists between energy levels of the medium whose energy difference may exceed the energy of any single pump photon energy.

Abstract: A microwave pumped excimer laser and method.

Abstract: Apparatus is provided for generating energy in the form of laser radiation. A tokamak fusion reactor is provided for generating a long, or continuous, pulse of high-energy neutrons. The tokamak design provides a temperature and a magnetic field which is effective to generate a neutron flux of at least 10.sup.15 neutrons/cm.sup.2.s. A conversion medium receives neutrons from the tokamak and converts the high-energy neutrons to an energy source with an intensity and an energy effective to excite a preselected lasing medium. The energy source typically comprises fission fragments, alpha particles, and radiation from a fission event. A lasing medium is provided which is responsive to the energy source to generate a population inversion which is effective to support laser oscillations for generating output radiation.

Abstract: A laser having a combination of end and side pumping so as to produce high power pulsed output with little or no delay between side pump pulses and laser output pulses, with suppressed spiking due to gain switching, and with high modulation rates. An active medium, such as a solid state laser rod, in a resonant optical cavity is pumped by a first optical pump source directing radiant energy into an end of the active medium so as to encourage or establish lasing operation in a desired transverse cavity mode, such as the TEM.sub.00 mode. A second optical pump source directs additional radiant energy into a side of the active medium so as to amplify the intensity of the laser output in the desired mode.

Abstract: A diode pumped slab laser (DPSL) that is cooled by a capillary heat pipe cooling apparatus. The DPSL contains a diode array that is cooled by one or more capillary evaporators that are adjacent to the diode array of the DPSL or contained within a thermally conductive substrate surrounding the diode array of the DPSL. The capillary evaporators convert the liquid phase of a working fluid to a vapor phase which is circulated to a condenser. The condenser causes the phase of the working fluid to change to a liquid phase which is then drawn back to the capillary evaporators by the evaporation of the working fluid within the capillary evaporator. In one embodiment, the diode array is interleaved with heat sink strips that conduct the heat away from the diode array strips and toward a closely spaced capillary evaporator wick facing the diode array. The vapor is carried away from the diode array in the channels formed between consecutive heat sink strips.

Abstract: A process and apparatus are disclosed for producing a beam of coherent radiation at essentially 459 nm by mixing, in a nonlinear crystal consisting essentially of KTP, two laser beams, one at essentially 1064 nm and the other at essentially 808 nm. The 1064 nm radiation is derived from a Nd:YAG laser that consists of an input mirror, an output mirror and a Nd:YAG crystal, and contains also the KTP crystal. The Nd:YAG laser is pumped by an essentially 808 nm semiconductor diode laser beam, which passes through the input mirror and through the KTP crystal into the Nd:YAG laser crystal where it is absorbed. The 1064 nm radiation oscillating inside the Nd:YAG laser resonator is mixed either with the said 808 nm pump beam or with 808 nm radiation provided by a second semiconductor diode laser whose light is coupled with the 1064 nm beam using a beamsplitter. The essentially 459 nm beam passes through the output mirror to a utilization device.

Abstract: A gas-laser arrangement in which the laser medium is optically pumped. An arc or spark discharge is formed to a helix, particularly by an axial magnetic field. The volume surrounded by the helical arc or spark discharge is optically excited, unimpeded by a physical wall, by radiation from the discharge, especially in the vacuum-uv spectral region, or by resonance lines. Due to the temperature difference between the helical discharge and the gas column along the helix axis, an inversion may be produced in the vicinity of the axis by appropriate choice of gas and the gas composition.

Abstract: The method of producing at least quasi-continuous lasing operation between initial and terminal lasing states comprising the steps of selecting a laser medium and cavity configuration (lasing frequency) with the laser medium containing upconverting material which provides for the exchange of energy between sufficient number of electrons at the terminal lasing state (manifold) so as to maintain population inversion between the initial and terminal lasing states during the lasing operation; and applying excitation energy of a suitable amount to the laser medium during at least a quasi-continuous time period.

Abstract: An optical fiber laser comprising a gain cavity in the form of a single mode optical fiber with integrally formed dichroic mirror end sections to provide feedback. The fiber core comprises a host material of silicate glass preferably doped with 0.01 to 1 weight percent of just erbium oxide as a lasing medium. The laser is end pumped at approximately 1.49 micrometers with a laser diode, preferably InGaAsP, and has an output at 1.54 micrometers.

Abstract: An apparatus and method for the deposition of uniform high-energy in a high pressure gaseous medium using an electrical discharge which is suitable for providing a population inversion therein with the consequent support of laser oscillation or amplification. The electric discharge is achieved without the use of a fast high-voltage, high current switch which must carry the entire discharge current, and requires lower discharge voltages than are normally used for such discharges. The high-energy, high-voltage discharge is initiated and controlled by a low-energy, high-voltage discharge which is in turn initiated and controlled by a yet lower energy preionization pulse which may derive from an electrical discharge or ionizing radiation. The simplicity of the present design permits the construction of rugged, reliable and inexpensive high-power gas lasers.

Abstract: Apparatus and a related method for controlling the characteristics of a high-power laser beam to provide a desired beam divergence, spectral content, and phase. A high-power beam, as from a free-electron laser, is directed into a conical Raman amplifier, together with a Stokes seed beam having the desired characteristics. The amplified output from the amplifier is divergent and its intensity falls of rapidly enough to allow the use of solid material optics without damage or destruction of the optical elements. The Raman amplifier is contained in part by two moving-gas windows, which seal the amplifier from the vacuum environment of the laser without the use of solid material optics. In one embodiment of the apparatus, the resulting output beam is precorrected for phase aberrations caused by optical elements and the transmission medium through which the beam is directed.

Abstract: An amplifier for use with fiber optic systems comprises a neodymium YAG crystal placed in series with a signal-carrying optical fiber. The ND:YAG crystal is supplied by the optical fiber with both the signal to be amplified, and pumping illumination. The pumping illumination is coupled onto the optical fiber by a multiplexing coupler which is used to combine the signal to be amplified and illumination from a pumping illumination source onto a single optical fiber. The pumping illumination inverts the neodymium ions within the ND:YAG crystal. The signal to be amplified propagates through this crystal to stimulate emission of coherent light from the neodymium ions, resulting in amplification of the signal.

Abstract: An improved railgap switch for use with pulse discharge gas lasers. The blade of the prior art railgap switches is replaced by an electrode having an "T" shaped cross section which provides two edges along which arcs are generated. The thickness of the "T" cross section near the edges at which arcs are formed is relatively uniform and oriented at a constant distance from the second electrode so that the thickness and distance remains unchanged despite ablation of the edges of the electrode. As a consequence the electrical properties of the switch are not altered significantly by ablation caused by repetitive operation of the switch.

Abstract: An adjustable, constant current power supply for use in electrically pumping negative impedance gas discharge lasers is disclosed. The power supply includes a voltage regulator and a constant current power source the output of the voltage regulator which is variable and controlled being connected to the input of the constant current power source. The output from the power supply is passed through a gaseous lasing medium located within a laser tube of the gas discharge laser in order to pump to the lasing medium. Be controlling the voltage fed into the constant current power source the current output therefrom can be altered in order to effectively vary the power output of the gas discharge laser.

Abstract: The present invention relates to a laser device in which an optical resonator and a slab-geometry laser medium are dioposed within said optical resonator. There is also a pump which optically excites said laser medium from one or both sides of the slab-geometry laser medium.

Abstract: An optically pumped single mode laser, e.g., Nd:YAG crystal (20) with planoconcave mirrors is increased in efficiency by an order of magnitude to about 8% by optics (25, 27) for focusing the high power multimode output of laser diode arrays (21, 22) into the mode volume (20') of the laser medium (20). A plurality of these optically pumped single mode lasers (1-4) may be cascaded in a ring with dichroic mirrors (M.sub.1 -M.sub.4) at the corners for coupling in the laser diode arrays, each having its own means for spatially tailoring its beam to concentrate pump distribution inside the lasing mode volume of the medium. An InGaAlAs pump diode (30) with its wavelength the same as the lasing medium makes the ring unidirectional.

Abstract: A plurality of slab-shaped laser media are surrounded by an internal reflection surface of a reflector member and kept substantially parallel to each other by a supporting member. Internal gaps are left between two adjacent ones of the media and additional gaps are left between two endmost ones of the media and the internal reflection surface. A plurality of lamp members are located within the internal and additional gaps so that each lamp member effectively excites two adjacent media in the internal gaps, and a single medium in cooperation with the internal reflection surface in each additional gap. Each medium produces a laser beam along a traveling direction as a result of excitation. Each lamp member may be a single or a plurality of elongated flash lamps parallel to or transverse to the traveling direction. Alternatively, each lamp member may be a flat excitation lamp having flat surfaces juxtaposed to each medium.

Abstract: A far-infrared laser structure is provided wherein a uniform longitudinal ectric field mode is provided for a radio frequency pump by means of a set of fully or near-fully circular ring shaped electrodes.

Abstract: A method is described for generating tunable far-infrared radiation. The apparatus includes a Schottky-barrier diode which has one side coupled through a conductor to a waveguide that carries a tunable microwave frequency, the diode having an opposite side which is coupled through a radiating whisker to a bias source. Infrared light is directed at the diode, and infrared light with tunable sidebands is radiated by the whisker through an open space to a reflector. The original infrared is separated from a tunable infrared sideband by a polarizing Michelson interferometer.

Abstract: An amplifier for use with fiber optic systems comprises a neodymium YAG crystal placed in series with a signal-carrying optical fiber. The ND:YAG crystal is supplied by the optical fiber with both the signal to be amplified, and pumping illumination. The pumping illumination is coupled onto the optical fiber by a multiplexing coupler which is used to combine the signal to be amplified and illumination from a pumping illumination source onto a single optical fiber. The pumping illumination inverts the neodymium ions within the ND:YAG crystal. The signal to be amplified propagates through this crystal to stimulate emission of coherent light from the neodymium ions, resulting in amplification of the signal.

Abstract: A method and apparatus for reducing gas pressure in a laser wherein a miniature cryogenic pump is constructed to comprise an integral part of a laser plasma tube. The pump includes a container which holds molecular sieve material, a conduit which permits communication between the container and the plasma tube, and a valve which controls the communication along the conduit. All connections between the container, conduit, valve and plasma tube are gas-tight so as to maintain the ion integrity of the plasma tube with respect to the atmosphere. In operation, a service engineer immerses the container in a refrigerant, such as liquid nitrogen, and opens the valve until the pressure in the plasma tube reaches the desired level. Thereafter the valve is closed and the container permitted to return to ambient temperature. Further in accordance with the present invention, means are provided for preventing over pressure in the container.

Abstract: X-ray laser method and apparatus for producing coherent radiation at, for example, energies of at least 40 eV, using Be-like Cr, N-like Ni, He-like Na, B-like Cr, Be-like Mn or similar multiply ionized species to pump appropriate high energy transitions in He-like or H-like N, O, F, C or rare gases, with associated laser transition gains of 4-50 cm.sup.-1.

Abstract: Prior power supplies adapted to provide power to the lasers of multiple ring laser gyros were inefficient in that they were required to have power output capabilities far in excess of that required to sustain laser operations. Such inefficiency is greatly reduced by the present power supply comprising a DC power source (30) for producing a firing voltage at a first terminal (40) and a sustaining voltage at a second terminal (42), and interface means (50) associated with each laser (12, 13, 14) for coupling the laser to the first and second terminals. The firing voltage is capable of firing each laser, and the sustaining voltage is capable of sustaining current flow through each laser after firing. Each interface means comprises a resistor (52, 53, 54) connecting the laser to the first terminal and a diode (55, 56, 57) for connecting the laser to the second terminal such that the diode does not permit current flow between the first and second terminals.

Abstract: A method of producing individual short laser pulses in which a stimulatable laser medium is excited by a pump pulse in order to produce a population inversion above a laser threshold value, the population inversion being kept below the threshold value after emission of the short radiation pulse. The laser medium is common to two resonators and from it energy in the form of the desired individual short laser radiation pulse is first taken from the first resonator by means of a first relaxation process of given threshold value, relatively short time constant and relatively low quality factor, after which the inversion in the laser medium is kept below the preset threshold value of the first resonance process by a second relaxation process of relatively long time constant and relatively high quality factor in the second resonator coupled to the first.

Abstract: In a slab laser, the optical pumping lamps extend transversely to the mean direction of the laser beam with the spatial period of the lamps being harmonically related to the spatial period of the zig-zag laser beam path within the slab, preferably with equal periods. In addition, the lamps are preferably positioned in registration over the lines of intersection of the central ray of the laser beam with respective broad face of the laser slab. A planar flashlamp reflector is employed for economy of fabrication. Directional lamp reflectors are employed for increasing laser efficiency and performance by discriminating against amplified surface waves.

Abstract: Apparatus and method for generating continuous wave 16 .mu.m laser radiation using gaseous CF.sub.4. Laser radiation at 16 .mu.m has been observed in a cooled static cell containing low pressure CF.sub.4 optically pumped by an approximately 3 W output power cw CO.sub.2 laser. The laser cavity employed was a multiple-pass off-axis-path two spherical mirror ring resonator. Unidirectional CF.sub.4 laser output power at 615 cm.sup.-1 exceeded 2 mW. Computer calculations indicate that for modest pump powers of about 40 W, approximately 1 W of emitted laser radiation at 16 .mu.m might be obtained.

Abstract: A lasing system for lasing at x-ray wavelengths. In one embodiment, a neoike sulfur ion S.sup.6+ plasma is caused to radiate on its 3d.fwdarw.2p transition to pump a lithium-like neon Ne.sup.7+ plasma to obtain x-ray lasing. In a second embodiment, a lithium-like silicon S.sub.i.sup.11+ ion plasma is caused to radiate on the 3d.fwdarw.2p transition to pump lithium-like magnesium Mg.sup.9+ plasma to obtain x-ray lasing.

Abstract: A method of optical pumping of an erbium laser and an apparatus therefor with an erbium laser medium, a light source for side-pumping the erbium laser medium, a neodymium laser medium for emitting a laser beam upon optical pumping by the light source, and an optical system for directing the laser beam from the neodymium laser medium to the erbium laser medium for side-pumping the erbium laser medium. Thus the erbium laser medium is side-pumped by the light source and also end-pumped by the laser beam emitted from the neodymium laser medium side-pumped at the same time by the light source in the same lamp house. Therefore the erbium laser can be optically pumped with high efficiency and offer a low threshold value.

Abstract: A passive thermal control system for a flashlamp-pumped dye laser utilizes heated deionized water in a heat exchanger located in the reservoir of the dye lasing solution to minimize the temperature gradients in the dye lasing solution by decreasing the difference in temperature between the dye lasing solution and the deionized water flashlamp coolant.

Abstract: The effective lasing lifetime of coumarin 102 in 50:50 ethylene glycol is gnificantly extended by increasing the rate of pumping and photolysis, with a flashlamp in a laser system having a pyrex ultraviolet filter and an inert cover gas.

Abstract: Laser apparatus having a very narrow (<1A) spectral output comprises a laser cavity having a metal vapor cell as one of the reflecting elements. This cell reflects the laser beam over a narrow wavelength region in the vicinity of one of the metal vapor's resonant absorption lines and achieves frequency locking to an atomic resonance line without any external frequency sensors or feedback loops.

Abstract: A pair of small diameter optical fibers are arranged in a side-by-side configuration, the first fiber providing a pumping source, and the second fiber doped with a material which will lase at the signal frequency. The signal to be amplified propagates through the second fiber to stimulate emission of coherent light from the lasing material, resulting in amplification of the signal. The refractive index of the first and second fibers are selected such that the signal in the second fiber is well guided, while the pumping light in the first fiber is unguided, yielding low losses in the second fiber but high transfer of the pumping light from the first fiber to the second fiber.

Abstract: A laser device pumped by RF microwaves at frequencies in the range of 8 to 12 GHz (X-band). An optical cavity containing a lasing medium is located within an RF cavity resonant at a frequency in the X-band. X-band RF energy is supplied from an RF source to a waveguide. A coupling plate, forming a common wall between the waveguide and the RF cavity, couples the RF energy from the waveguide into the cavity to produce a standing wave pattern therein which excites the lasing medium. Various coupling plate designs are disclosed. In an alternative embodiment, a plurality of separate optical cavities containing separate lasing media are located within the RF cavity and are commonly excited by the microwave energy.

Abstract: Method and apparatus for amplification of a laser pulse in a free electron laser amplifier where the laser pulse duration may be a small fraction of the electron beam pulse duration used for amplification. An electron beam pulse is passed through a first wiggler magnet and a short laser pulse to be amplified is passed through the same wiggler so that only the energy of the last fraction, f, (f<1) of the electron beam pulse is consumed in amplifying the laser pulse. After suitable delay of the electron beam, the process is repeated in a second wiggler magnet, a third, . . . , where substantially the same fraction f of the remainder of the electron beam pulse is consumed in amplification of the given short laser pulse in each wiggler magnet region until the useful electron beam energy is substantially completely consumed by amplification of the laser pulse.

Abstract: A method for simultaneous amplification of laser beams with a sequence of frequencies in a single pass, using a relativistic beam of electrons grouped in a sequence of energies corresponding to the sequence of laser beam frequencies. The method allows electrons to pass from one potential well or "bucket" to another adjacent bucket, thus increasing efficiency of trapping and energy conversion.

Abstract: The invention relates to a method and an apparatus for maintaining a predetermined beam direction in a laser pulse transmitter having a laser resonator including a laser rod (1) with a rotating prism (2) at one end and output coupler (3) at its other end, as well as a flash lamp (4) which is energized to emit a flash pulse for pumping the laser rod (1) with light energy. In accordance with the invention, the deviation of the beam from the predetermined beam direction is measured with the aid of a measuring circuit (13-18), subsequent to which the working point of the laser pulse transmitter is adjusted in response to the magnitude and polarity of the deviation to a predetermined working point corresponding to the predetermined beam direction, e.g. by altering the flash pulse energy.

Abstract: An anti-Stokes Raman laser is disclosed which is tunable over a range of 10-70 cm.sup.-1. An alkali halide is used as the lasing medium and a metastable halide population inversion is created with respect to the ground state of the halide by selective photodissociation of the alkali halide. A pump laser is then employed to move the population from the metastable state to a region near an intermediate state of the halide. The population subsequently falls back to the initial ground state, thereby creating the anti-Stokes Raman emission. Since the intensity of the photodissociation is directly proportional to the amount of population inversion achieved, and hence, to the region the population may be pumped to, the tuning of the output anti-Stokes Raman lasing is a function of the intensity of the initial photodissociation.

Abstract: A laser cooling system has a coolant formulated to act as a heat exchanger and a transparent optical medium of matching refractive index between the flashlamp, silver reflectors and laser rod. The coolant has one or more fluorescent dyes and an inorganic pH buffering additive therein and the lamp is in a cerium doped envelope. A method is provided for measuring the operation time of a laser having a cooling system and a coolant having fluorescent dyes therein and actuating a solenoid valve after a predetermined operational life of the laser to release a dye additive into the coolant to maintain the efficiency of the laser.

Abstract: An ion laser with a gas discharge vessel, for example a helium-selenium ion laser, utilizing cataphoretic vapor transport provides monochromatic exit radiation in a parallel beam of high intensity. The discharge takes place in a tube of high silica glass surrounded at some spacing by an envelope tube that is subject to cooling and is therefore gas-tight for helium. The envelope tube has a configuration or partial partition that provides condensation chambers for the vapor. Advantages are increased power especially for compact and short configurations, with high reliability, safety, and service life.

Abstract: A laser system generates high energy ultra-short pulses using a dye cell amplifier driven by ultra-short pulses from a dye laser and pumped by pump pulses from a laser amplifier. The laser amplifier and dye laser are synchronously driven and pumped by the same laser such that the signal pulse from the dye laser arrives at the dye cell amplifier immediately upon the completion of population inversion therein in response to the pump pulse. Efficient high-power, ultra-short laser pulses are obtained from the dye amplifier, since amplified spontaneous emission (ASE) is avoided. Doubler crystals are used to provide the pump pulses to the dye laser from the common driver laser and to provide pump pulses from the laser amplifier to the dye cell amplifier at the proper wave length for the materials used therein. This system is tunable by selecting appropriate dyes for the dye laser and dye cell amplifier and/or tuning elements within the dye laser cavity.

Abstract: A method and apparatus for producing stable and reproducible ultra-short lasing radiation pulses are disclosed. The duration of incoming pumping pulses for the dye laser arrangement is reduced in stages to produce the ultra-short pulses. A first dye laser cavity of a series of at least two cascaded dye laser cavities is excited with lasing radiation pulses. The lasing radiation pulses emerging from each dye laser cavity of the series are directed into the next successive dye laser cavity of the series. The photon cavity lifetime of each dye laser cavity of the series is sufficient for a given duration of the incoming pumping pulses to produce the ultra-short pulses emerging from the final dye laser cavity of the series. The maximum photon cavity lifetime of each dye laser cavity of the series is selected to thereby reduce in stages the duration of the incoming pumping pulses. This reduction yields from the final dye laser cavity of the series the ultra-short lasing radiation pulses.

Abstract: A device which uses a light signal to control the amplification of light is disclosed. Optically active ions in a laser material are pumped to an intermediate energy state by light of a first frequency, and thereafter pumped from the intermediate energy state to an upper energy state by light of a second frequency. Lasing occurs when the optically active ions fall back to the intermediate energy state. When the intensity of the light of the first frequency is below the threshold pumping level, no laser action can occur even though the intensity of the light of the second frequency is above its threshold pumping level. Thus a large output power can be controlled by a small input power.

Abstract: A long rare-gas halide excimer light source excited by a capacitively coupled discharge pumps a dye laser with high efficiency in a configuration matched to the length of the discharge.

Abstract: An efficient recombination laser comprises a resonant laser cavity, a gaseous laser material disposed in the cavity, and means for providing a plasma discharge in said laser material, which plasma discharge is confined to a cylindrical region along the axis of the laser cavity. The plasma in the gaseous laser material expands outward radially from the cylindrical region at the axis of the cavity and cools by interacting with the adjacent unexcited gas. The maximum laser gain is provided in an annular region, which annular region is adjacent to and surrounds the initial discharge cylindrical region. In one embodiment of the present invention, the means for providing the plasma discharge comprises two pin-type electrodes which extend into the cavity along the cavity axis.

Abstract: The invention disclosed is a dual wavelength output laser for use in laser rangefinders. Two different laser active media, e.g. CO.sub.2 and DF, are operated in separate laser cavities arranged in tandem in the same optical resonant cavity, resulting in a co-linear dual wavelength laser output.

Abstract: A technique for lasing a gas in a gas lasing device to obtain stimulated light emission at a desired wavelength by bottlenecking the high gain transitions in the gas so that certain low gain transitions which will yield the desired wavelength are now able to oscillate. This technique comprises the steps of optimizing the mirror transmission for the desired light frequency, and pumping the laser gas with a pulse whose width is much longer than that required to bottleneck the high gain transitions. This technique may be utilized with both molecular and atomic gases.

Abstract: A thermally pumped laser. The laser features an emitter, a collector spaced apart from the emitter, and reflecting elements adjacent to the space between the emitter and collector to form a cavity. A heat source is provided for heating the emitter to drive electrons from the emitter to the collector. Vapor such as cesium vapor is disposed in the cavity between the emitter and the collector to form the lasing medium. An additive selected to be in resonance with specific excited states of the atoms may be intermixed with the chosen vapor. The additive assists in depopulating the specific states of the atoms, thereby creating or enhancing a population inversion in the atoms of the vapor so that lasing may occur. The laser may be operated both in a pulsed and in a d.c. mode.

Abstract: The present invention relates to a system for generating extreme ultraviolet (XUV) radiation. The process utilizes pulsed plasmas to create a high density of ions in which non-linear frequency upconversion into the XUV region can occur. In particular, metals are utilized as the lasing medium in the present invention, since the ions of these metals do not absorb wavelengths in the XUV region and a significant level of XUV output may be obtained. Conventional UV lasers are utilized as the upconverters for the ionized metals.