Abstract: A method and apparatus is provided for stabilizing output beam parameters of a gas discharge laser by maintaining a constituent gas of the laser gas mixture at a predetermined partial pressure using a gas supply unit and a processor. The constituent gas of the laser gas mixture is provided at an initial partial pressure and the constituent gas is subject to depletion within the laser discharge chamber. Injections of the constituent gas are performed each to increase the partial pressure by a selected amount in the discharge chamber preferably less than 0.2 mbar per injection. A number of successive injections is performed at selected intervals to maintain the constituent gas substantially at the initial partial pressure for maintaining stable output beam parameters. The amount per injection and/or the interval between injections may be varied based on the measured value of the driving voltage and/or a calculated amount of the constituent gas in the discharge chamber.

Abstract: In a method for determining the life of a laser light source for use with an exposure apparatus using KrF or ArF excimer laser as a light source for exposure, the method for determining the life of the laser light source is implemented by subjecting an excimer laser light source to single oscillation by blocking a pulse light, acquiring data relating to plural parameters for learning a periodical variation of the excimer laser light source and its structuring parts through an interface, and determining the life of the excimer laser light source on the basis of the data acquired. Those data is acquired on a regular basis in accompany with the work for exchanging gases at the time of exchanging gases for the excimer laser light source.

Abstract: A laser assembly, particularly one employing a gas lasing medium, has at least one lasing gas supply reservoir that is separate from the housing enclosure for the laser's optical cavity. A flexible or semi-flexible conduit supplies lasing gas from the reservoir to the optical cavity, so as to allow the laser per se and the gas reservoir to be manufactured separately and then connected by the tubing, thus simplifying the design and manufacturing process. The laser is preferably operated as a pulsed gas discharge laser that produces a continuous laser output. One or both of the laser's cavity mirrors may be coated with fine parallel lines which constrain the laser output to be linearly polarized. The lasing medium may have a stepwise or tapered structure, which provides for selection of the most desirable TEM00 mode. In addition, the lasing medium cavity may be cooled by a multiple cooling jacket structure to facilitate placement of the coolant inlet and outlet ports.

Abstract: A technique of stabalizing during operation a gas mixture with a gas composition initially provided within a discharge chamber of an excimer or molecular fluorine gas discharge laser includes monitoring a temporal pulse shape of the laser beam and adjusting and/or determining the status of the gas mixture based on the monitored temporal pulse shape. The monitored temporal pulse shape is preferably compared with a reference temporal pulse shape. The difference or deviation between the monitored temporal pulse shape and a reference temporal pulse shape is calculated. The amount of and intervals between gas replenishment actions are determined based on the calculated deviation. The energy of the beam is also monitored and the driving voltage and gas actions are adjusted to stabilize the energy, energy stability and/or energy dose.

Abstract: A gas mixture of a gas discharge laser such as an excimer or molecular fluorine laser is stabilized. The gas mixture of the laser includes a constituent halogen containing molecular species such as F2 or HCl which is subject to depletion from an initial optimum concentration. When the gas mixture is energized by a pulsed discharge circuit, the amplified spontaneous emission (ASE) signal is monitored. The status of the gas mixture is determined based on the monitored ASE signal. Stimulated emission is preferably filtered or blocked for more precise ASE signal monitoring. The gas mixture is preferably replenished using small halogen injections, total pressure adjustments and mini and partial gas replacements based on the evolving gas mixture status determined from the monitored ASE signal.

Abstract: A method and apparatus are provided for delivering a laser beam from a laser, such as an F2 laser, to a target through a sealed enclosure. The enclosure is evacuated and back-filled with an inert gas repeatedly for a number of times sufficient to adequately deplete any air, water, hydrocarbons or oxygen within the enclosure. Thereafter, an inert gas flow is established and maintained within the enclosure during operation of the laser. Propagation with significant transmittance of a sub-200 nm beam through the enclosure is particularly enabled.

Abstract: In a method for determining the life of a laser light source for use with an exposure apparatus using KrF or ArF excimer laser as a light source for exposure, the method for determining the life of the laser light source is implemented by subjecting an excimer laser light source to single oscillation by blocking a pulse light, acquiring data relating to plural parameters for learning a periodical variation of the excimer laser light source and its structuring parts through an interface, and determining the life of the excimer laser light source on the basis of the data acquired. Those data is acquired on a regular basis in accompany with the work for exchanging gases at the time of exchanging gases for the excimer laser light source.

Abstract: A laser apparatus comprises a plurality of laser beam sources which use, as laser media, mixed gases containing at least one common gas component; at least one common gas supply source for supplying, to the respective laser beam sources, the common gas component for constituting the mixed gases; and one or more gas flow amount-adjusting units for adjusting flow amounts of the common gas component supplied from the common gas supply source and other gas components for constituting the mixed gases so that the gas components are supplied to the respective gas laser beam sources. It is unnecessary to provide gas tanks for each of the laser beam sources. The arrangement of the gas supply equipment is simplified, and the safety is improved. A plurality of the laser apparatuses are preferably installed to a circuit element production line provided with a plurality of exposure apparatuses.

Abstract: A method is provided for determining the status of a gas mixture of a laser system including a gas discharge laser which generates an output beam and has a discharge chamber containing a gas mixture within which energy is supplied to the gas mixture by a power supply via application of a driving voltage to a discharge circuit. A master data set of an output parameter such as any of output beam energy, bandwidth, spectrum width, long axial beam profile, short axial beam profile, beam divergence, energy stability, energy efficiency, width of the discharge, temporal beam coherence, spatial beam coherence, spatial pulse width, amplified spontaneous emission and temporal pulse width versus an input parameter such as driving voltage is generated corresponding to an optimal gas mixture status, preferably after a new fill and typically at the factory, and alternatively following a new fill at the fab.

Abstract: The average power capability of a solid-state laser is increased by cooling the lasing element to a cryogenic temperature. The laser pump chamber is configured to define a flow path for circulating cryogenic fluid. The cryogenic cooling is achieved for rod, slab, active-mirror or disc amplifier-type lasing elements.

Abstract: An excimer laser system with an automatic fluorine control system to permit precise control of the fluorine concentration within an F.sub.2 "sweet spot" in a gas discharge laser chamber. This is done with a computer control system which monitors laser parameters, determines .DELTA.E/.DELTA.V, the change of pulse energy with voltage, and automatically and precisely controls the fluorine concentration based on .DELTA.E/.DELTA.V without the need to actually measure the fluorine concentration.

Abstract: A gas laser outputs a prescribed high power from the start of laser oscillation immediately after the laser gas is changed. The laser, in which used laser gas in a laser chamber (1) is replaced with a fresh laser gas, is provided with: a gas leaving means, which leaves a prescribed amount of used gas for mixing with the fresh laser gas during laser gas replacement, or an impurity gas adding means which provides a prescribed amount of impurity gas for mixing with the fresh laser gas; and a controller (11). It is preferable that the concentration of the used gas after a replacement is within a range of 1.5-60%. The gas leaving means can be a gas discharge control mechanism (10), which controls the amount of used gas exhausted so that a prescribed amount of used gas can be left for mixing with the fresh gas, or a laser gas container (21), which can provide a prescribed amount of stored used gas for mixing with the fresh gas.

Abstract: In an excimer laser apparatus in which halogen gas, rare gas and buffer gas are fed into the laser chamber, before laser oscillation, the oscillation stop time is calculated, and, if the calculated oscillation stop time exceeds a prescribed time, the calculated oscillation stop time is used to calculate a feeding amount of mixed gas comprising rare gas or buffer gas, and the mixed gas is fed, prior to laser oscillation, in the calculated feeding amount; stable laser output is thereby obtained from the initial period of laser oscillation.

Abstract: The present invention relates to a method and a device for purifying methane gas in a Raman cell (20). When pumped laser light having a high power passes through the Raman cell containing methane gas, a portion of the methane can be decomposed, and then highly reactive methyl radicals are formed. They can react with each other and as time passes form organic compounds, which are deposited on the inner side of the windows (22a, 22b) of the Raman cell. A trap (26) comprising calcium grains (27), which absorb the methyl radicals, is introduced in the Raman cell (20). The methane gas, which comprises a small content of methyl radicals, is made to come in contact with the calcium grains (27), whereby a reaction occurs between the methyl radicals and the calcium grains, so that calcium carbide and calcium hydride are formed. The methane gas is driven around in the Raman cell (20) and through the trap (26) by means of a compressor wheel (28) driven by a motor (29c).

Abstract: The present invention provides an electric discharge gas laser having a laser cavity in which is contained a laser gas and a fan for circulating the laser gas. The fan is supported by an active radial magnetic bearing system and driven by a brushless DC motor in which the rotor of the motor and the rotors of at least two radial bearings are sealed within the gas environment of the laser cavity and the motor stator and the coils of the bearing magnets are located outside the gas environment. No thrust bearing is provided. Axial positioning of the shaft is provided by reluctance centering produced by the at least two radial magnetic bearings and the brushless DC motor. In a preferred embodiment the motor stator is larger in the axial direction than the rotor to increase the magnetic centering effect.

Abstract: An improved excimer laser is disclosed. In one embodiment, the laser includes laser beam generating circuitry operable to generate a laser beam and a vessel enclosing the laser beam generating circuitry. The vessel contains a volume of gas conducive to the formation of the laser beam by the laser beam generating circuitry. The vessel has a wall with a beam aperture formed therein to permit the laser beam generated by the laser beam generating circuitry to pass through it. A window mount assembly is attached to the wall of the vessel. The window mount assembly encloses a beam cavity and has a window that transmits the laser beam. The window is positioned at a first, closed end of the beam cavity. The beam cavity has a second, open end adjoining the beam aperture formed in the vessel wall. The beam cavity has a lateral surface extending between the first and second ends. A plenum lies outside the beam cavity. A gas handling system extracts the gas from the vessel and provides the gas to the plenum.

Abstract: The device and method of the invention provide a neutralizing compound that reacts with acid gases generated in laser exhaust to yield an insoluble non-toxic powder.

Abstract: A continuous wave photolytic iodine laser has a gain cell for receiving a continuous supply of gaseous fuel. The gain cell is connected to laser beam transfer optics, a laser resonator for shaping a laser beam, and a lamp. The lamp is driven by a microwave subsystem such that a laser gain medium is pumped through the gain cell. The continuous wave photolytic iodine laser of the present invention incorporates a closed loop fuel system for presenting gaseous fuel to the gain cell at a rate sufficient to sweep any lasing by-products out of the gain cell, thereby preventing quenching of the lasing process. The fuel system also includes a condenser for converting the gaseous fuel to a liquid after it has passed through the gain cell, a scrubber for removing the by-products of the lasing process from the fuel, and an evaporator for converting the recycled liquefied fuel back to a gas. The closed loop fuel system also includes a pump for pressurizing and transporting the liquefied fuel.

Abstract: A gas discharge laser with fast response gas temperature control to maintain laser gas temperature within desired limits during burst mode operation. Preferred embodiments include a passive temperature stabilizer having fins with surface areas exposed to flowing laser gas at least equal to the surface area of the cooling fins of a laser gas heat exchanger. Preferred embodiments utilize heating elements and coolant flow control to regulate laser gas temperatures using processors programmed to anticipate idle periods.

Abstract: An excimer laser system with a fluorine control having a fixed volume inject bottle in which fluorine is injected prior to it being injected into the laser chamber. A manifold and feedback control system is provided to permit precise injection at rates approaching continuous fluorine injection. The system permits the laser to be operated in a small sweet spot as measured by a narrow range of charging voltage.

Abstract: Disclosed is a laser useful in, e.g., photolithography or medical surgery. In one embodiment, the laser comprises a discharge chamber and heat-generating electronics that are enclosed in a baffled enclosure that requires less cooling air to reliably cool the components in the enclosure than previous unbaffled enclosures. A method of reducing the amount of conditioned air is also provided. In a further embodiment, the laser has a heat-exchange system that acts quickly in response to changes in laser gas temperature by adjusting a flow-proportioning valve regulating water flow through a heat exchanger, thereby providing a continuously variable rate of heat exchange through the heat exchanger to maintain the lasing gas temperature constant. Methods of providing a laser beam and of improving the uniformity of a laser beam are disclosed, as are photolithography methods utilizing a laser and method of this invention.

Abstract: An excimer laser with a laser gas containing fluorine in which the fluorine concentration is maintained continuously at or substantially at desired predetermined levels. A real time or substantially real time fluorine monitor provides a feedback signal to a fluorine flow control system which provides continuous fluorine injection flow into the laser chamber to precisely compensate for fluorine depletion and maintain fluorine concentration precisely at desired levels. In a preferred embodiment, fluorine detector which may be a chemical detector periodically measures the fluorine concentration in laser gas discharged from the laser in order to calibrate the real time or substantially real time fluorine monitor. In a second preferred embodiment, the continuous inlet flow is from two gas sources, one containing fluorine, a noble gas and a buffer gas and the other containing only the noble gas and the buffer gas.

Abstract: A method for extending the gas lifetime of an excimer laser by removing CF.sub.4 impurity, which comprises:a) reacting CF.sub.4, an undesirable impurity which forms and is contained in the lasing gases, with an amount of an oxidizing gas additive effective to produce one or more compounds which are condensible with refrigeration means, without reducing laser output below a predetermined acceptable level; andb) condensing said one or more compounds produced in step a) with refrigeration means, substantially without condensing said one or more rare gases therewith, thereby removing said CF.sub.4 impurity from said excimer laser and extending the gas lifetime of the laser.

Abstract: A gas laser includes an enclosure forming a first chamber, a second chamber and a lasing chamber which communicates through a first opening to the first chamber and through a second opening to the second chamber. The lasing chamber has a pair of reflectors defining a Fabry-Perot cavity. Separate inlets enable different gases to be introduced into the first and second chambers. A first cathode within the first chamber is provided to produce positive ions which travel into the lasing chamber and a second cathode of a pin-hollow type within the second chamber is provided to produce negative ions which travel into the lasing chamber. A third inlet introduces a molecular gas into the lasing chamber, where the molecular gas becomes excited by the positive and negative ions and emits light which lases in the Fabry-Perot cavity.

Abstract: A process for selecting an operating range for a narrow band KrF or ArF excimer laser. The laser is operated at a desired pulse energy until the fluorine concentration has depleted sufficiently so that the charging voltage needed for the desired pulse energy is at or near a predetermined maximum range. The average charging voltage, the average line width, and the average energy sigma are recorded; and the fluorine concentration is estimated or determined. A quantity of fluorine, at least sufficient to cause a measurable decrease in the charging voltage needed to produce the desired pulse energy, is injected; and another set of data is recorded. Another similar quantity of fluorine is injected, and another set of data is recorded. These two steps are repeated until the voltage is at or near a predetermined minimum voltage range. The recorded data are used to select an optional operating range. The data may be plotted to make the selection easier.

Abstract: There is provided a cylindrical valve 20 for placement in the flow path of a singlet-delta oxygen generator 12 that feeds O.sub.2.sup.* to a chemical laser gain medium 14. The feed path 22 includes a sharp 90.degree. bend 24 that causes fluid velocity variations in O.sub.2.sup.* entering the gain medium 14. Integral with the valve 20 is a tubular structure 12 having a partial circumferential radially extending surface 44 fitted with "O" ring for sealing and opening the feed path between the "O.sub.2.sup.* " generator 12 and gain generator 14. A series of vanes 32, 34, 36 disposed in velocity control zones 50, 52, 54 and 56 are integral with the valve 20 for leveling out the velocity variations and controlling the wake formation 58, 59 and 60 in the O.sub.2.sup.* entering the gain generator 14.

Abstract: A gas laser oscillator has at least a partial reflection unit and a total reflection unit, each of which comprises an extension unit for connecting between a gas introducing unit and a fixed block unit. The gas introducing unit has a gas inlet port for circulating laser gas in a laser tube, and the fixed block unit is provided for fixing a reflector. A gas inlet port of the gas introducing unit is arranged with a predetermined interval of 120 mm or more so that the reflectors are free from contamination by floating powders and deterioration by ultraviolet lays.

Abstract: An improved method and apparatus for regeneration and reuse of He--N.sub.2 --CO.sub.2 mixed gas for carbon dioxide gas laser. The laser gas after use is contacted with a noble metal catalyst (for example, Pt--Al.sub.2 O.sub.3) at a temperature of 200.degree.-300.degree. C. to react CO and O.sub.2 formed by laser discharge so as to form CO.sub.2. A suitable quantity of moisture in the contained laser gas causes steam-reforming reaction of H.sub.2 O and CO, and reaction of H.sub.2 and O.sub.2 following thereto, and continuous operation over a long period is thus possible. Poisoning of the catalyst by NO.sub.x is suppressed at this relatively high temperature of reaction. Activity of the catalyst, when decreased, may be recovered by reactivation by passing a reactivating gas consisting of carbon monoxide, oxygen and helium through the catalyst bed at a temperature of 400.degree. to 500.degree. C.

Abstract: In order to improve an oxygen-iodine laser comprising a reaction unit for the generation of a gas stream composed of excited oxygen by chemical reaction between a reaction liquid and a reaction gas, a steam trap with a condensation chamber, in which steam entrained by the gas stream is condensed onto cold surfaces, an iodine injector, which injects iodine into the gas stream to generate a laser-active gas mixture, and a laser resonator with the laser-active gas mixture flowing through it, in such a way as to obtain a gas stream as free from steam as possible using the simplest possible means, it is proposed that the cold surfaces for separation of the steam are formed by liquid surfaces of a condensation liquid moved in the condensation chamber.

Abstract: A continuous wave photolytic iodine laser has a gain cell for receiving a continuous supply of gaseous fuel. The gain cell is connected to laser beam transfer optics, a laser resonator for shaping a laser beam, and a lamp. The lamp is driven by a microwave subsystem such that a laser gain medium is pumped through the gain cell. The continuous wave photolytic iodine laser of the present invention incorporates a closed loop fuel system for presenting gaseous fuel to the gain cell at a rate sufficient to sweep any lasing by-products out of the gain cell, thereby preventing quenching of the lasing process. The fuel system also includes a condenser for converting the gaseous fuel to a liquid after it has passed through the gain cell, a scrubber for removing the by-products of the lasing process from the fuel, and an evaporator for converting the recycled liquefied fuel back to a gas. The closed loop fuel system also includes a pump for pressurizing and transporting the liquefied fuel.

Abstract: The gas mixture leaving the laser apparatus (1) is recycled to a permeator (45) which separates it into two flows. The discharge from the permeator is expanded in an expansion turbine (27) coupled to a compressor (35) for exerting suction on the recycled mixture, which makes it possible to obtain the desired reduced pressure in the laser apparatus. Applications to power laser apparatuses with nitrogen/carbon dioxide mixture, intended for cutting materials.

Abstract: A laser oscillator has a casing 10. A cooling medium is supplied from an inlet port 134 to a heat exchanger 8 via a pipe 35, and discharged form it via a pipe 37 and an outlet port 136. The ports 134 and 136 are symmetrically positioned relative to a center line of the casing when seen from upward. An inlet port 340 and an outlet port 342 have a similar positional relation ship thereto.

Abstract: A getter for immobilizing water and organic molecules which may be present as impurities in an enclosure for a high power laser. The getter is formulated from selected zeolite compositions having a pore or channel size suitable for immobilizing water and a size range of organic molecules up to about 40 microns. A binder is used to provide a getter having sufficient strength to allow use of the getter in a laser enclosure in a telecommunications application. The binder also provides a substantially dust free getter body to maintain the cleanliness of the interior of the laser enclosure. Getters which immobilize only organics or only water are contemplated.

Abstract: Provided is method and apparatus for regenerating basic hydrogen peroxide (BHP) solution. Such solution is run through filters which are alternated for continuous filtration thereof, while the non-used filter is being cleaned. The filtered BHP solution is then reacted with H.sub.2 O.sub.2 and KO.sub.2 or KOH in a cooled reactor and again filtered and fed to a cooled storage tank as replenished BHP solution. The replenished BHP solution can then be fed to a singlet oxygen generator (SOG) for reaction with Cl.sub.2 to emit singlet delta oxygen (to fuel a COIL laser system) and depleted BHP solution, which is then recycled for filtration and regeneration as before. Thus the process of the invention provides for continuous regeneration of BHP solution for extended use in a COIL. That is, extended COIL run times are required by a COIL for welding and/or cutting operations. At the same time the process of the invention minimizes the amount of BHP required to run the COIL since the BHP is regenerated and recycled.

Abstract: In a gas laser (1) with a laser gas circulation path (5) in which a fan (4) conveys the laser gas (6) through a laser discharge space or tube (2) and a cooling system (3a, 3b), the gas throughput is increased by a bypass (8) of the laser discharge space (2). In the bypass may be a filter, cooler and catalyst for treating that portion of the laser gas flowing therethrough. The volume of gas diverted through the bypass may be adjusted to improve the efficiency of the laser.

Abstract: A decontaminate apparatus for a laser system includes a laser having a compartment housing having a base and walls formed into a cavity and having a compartment cover having at least a portion thereof porous to predetermined gases used in laser system optical cavities. The compartment housing cavity is filled with a selected decontaminating material held therein by the porous cover and is attached in the laser system housing so that selected contamination in the laser system optical compartment gas is absorbed by the selected material in the compartment. The compartment cover can be made of a porous silica.

Abstract: A high power, closed cycle photolytic atomic iodine laser system having a high molecular weight gas as a laser fuel and which requires a high velocity flow of the laser fuel, the laser fuel to be in a selected low pressure range, and the laser fuel to be of very high purity. The laser system has a turbo-molecular blower for circulating the laser fuel. The turbo-molecular blower provides the high velocity flow, the selected low pressure through the laser gain cell, and a high compression ratio. The velocity is in a range of about 1 m/s to 100 m/s, the compression ratio being in a range from about 10:1 to 1000:1, the selected low pressure in a range of about 5 to 60 Torr, and the turbo-molecular blower not contaminating the laser fuel of the closed cycle fuel system by the use of ferrofluidic rotary seals. The turbo-molecular blower has a blower assembly that provides a continuous, high velocity and pressurized gas flow.

Abstract: A laser system which realizes its stable operation. In the system, a spectrum width of laser light dischargingly excited in a laser chamber is detected by a spectrum width monitor. A controller controls, on the basis of the detected spectrum width, a replenishment amount of gas to be replenished from an F2 gas cylinder into the laser chamber through a sub-tank and on-off valves to cause the spectrum width to become constant.Further, when replenishment of a halogen gas diluted with a buffer gas is carried out, a gas exhaustion step of keeping the internal total gas pressure of the laser chamber constant is omitted.In addition, a laser oscillation pulse number is counted for a predetermined period of time and a replenishment amount of the halogen gas is carried out according to the count value.

Abstract: A laser arrangement includes an outer envelope and an inner alumina tube between which insulating material is located. The insulating material has a plurality of apertures therein in its transverse end faces, the aperture being arranged at each end on two circle of similar radii. Hydrogen reservoirs are located within the apertures. During operation of the laser arrangement, the reservoirs become heated causing hydrogen to be evolved and diffused through to the laser active medium, improving the efficiency of the laser operation. When laser action ceases, the arrangement cools and hydrogen returns to the reservoirs. Efficiency enhancing gases other than hydrogen may be used in the arrangement.

Abstract: An excimer gas laser using a fluorine/krypton/neon gas mixture is provided with separate fluorine/krypton/neon and krypton/neon gas sources for use in replenishing the gas mixture. A bleed-down mechanism is also provided for draining a portion of the gas mixture from the excimer laser. A control mechanism controls operation of the separate fluorine/krypton/neon and krypton/neon sources and the bleed-down mechanism to selectively vary the gas mixture within the excimer laser to maintain an overall optimal laser efficiency. Preferably, the control system monitors operational parameters of the excimer laser including gain, wavelength, bandwidth and pulse rate, to determine whether the gas mixture within the excimer laser may have changed from an optimal mixture. The control system controls operation of the separate fluorine/krypton/neon and krypton/neon sources to compensate for changes in the operation parameters of the laser to thereby maintain high overall laser efficiency.

Abstract: An apparatus for purifying laser gas, in particular for excimer and F.sub.2 lasers, employs liquid nitrogen (12) for freezing impurities out of the laser gas, the freeze-out temperature being set by means of the pressure above the surface (14) of the liqid nitrogen (12).

Abstract: An excimer laser including a gas reservoir in which gas discharge is effected with the participation of halogen gas, comprises a collecting receptacle which communicates both with the gas reservoir and a halogen gas supply through conduits provided with shutoff valves. This apparatus is suitable for carrying out a method of refilling the gas reservoir of the excimer laser with halogen gas even if the pressure of the halogen gas supply is low and its volume restricted.

Abstract: A housing in a laser system encloses a cathode and a displaced anode and gases ionizable and reactive chemically when a voltage pulse produces a cathode-anode electrical discharge. Moving air cools the components (capacitors, thyratron and triggering circuitry) for producing the voltage pulses. The laser gas temperature is continuously regulated at a particular value whether or not there is an electrical discharge. The concentration of one of the gases in the chamber is regulated to values alternately on opposite sides of an optimal value to provide an optimal energy in each chemical reaction of the gases. The gases are recirculated as by a fan driven on a shaft by a pair of motors and are filtered during such recirculation. The shaft speed is regulated at a particular value and the motor currents are regulated to be equal. Any ozone formed in a compartment holding the high voltage terminals is purged by passing a neutral gas (nitrogen) through the compartment to the atmosphere.

Abstract: An excimer laser apparatus is provided with a compact high efficiency dust particle removal means which is capable of maintaining the windows clean with only a small volume of purging gas, and which prevents deterioration of aperture masks without having to increase the cavity length or risking the possibility of leakage from piping connections. The excimer laser apparatus uses, as dust particle removal means, filters (13a and 13b) made of metal or ceramic which is non-reactive with fluorine. A ground potential dust collector can be provided at a downstream side of a static dust particle remover, having an anode and a cathode, for collecting any dust particles which have passed through the static dust particle remover.

Abstract: Mixing power laser apparatus, comprising a generator of a flow of excited nitrogen (1), and structure (6; 19) to introduce a flow of CO.sub.2 into the flow of excited nitrogen. The generator (1) is of the cold corona electric discharge type operating at a pressure greater than 0.3.times.10.sup.5 Pa, and is coupled to a waveguide (2) with mirrors (3, 4) opposed along a principal direction of the waveguide. For use particularly in cutting material.

Abstract: A repetitively pulsed, high energy, closed cycle photolytic atomic iodine lasers operates at 1.315 microns. Using an iodine (I.sub.2) removal system for the photolyzed C.sub.3 F.sub.7 I laser fuel, more than 70 joules/pulse is output in the fundamental mode from a M=3 confocal unstable resonator at a 0.5 Hz repetition rate. The closed cycle iodine (I.sub.2) removal system consisted of a condensative-evaporative section, two Cu mesh I.sub.2 sections, and an internal turbo-molecular blower. This closed cycle system uses C.sub.3 F.sub.7 I gas at 10-60 torr absent of I.sub.2. The turbo-molecular blower is able to push high molecular weight gases at high velocities. The turbo-molecular blower is able to produce longitudinal flow velocities greater than 10 m/s through the 150 cm long by 7.5.times.7.5 cm.sup.2 cross sectional photolytic iodine gain region. In addition to the high energy output, the resulting 7-12 .mu.sec laser beam has a beam quality less than 1.

Abstract: A halogen generator which uses a material which absorbs commercially available halogen and, on being heated, releases the halogen in a very pure form, i.e. >99.7%. Such a generator can be used in a gas management system for an excimer laser in which the laser gas contains a halogen donor, an active rare gas and an inert gas diluent. Cleaners are provided to enable the removal from the laser gas mixture of contaminants which build up in operation of the laser and the halogen gas generator is provided to replace halogen lost in the contaminants and elsewhere. The generator can be operated even when the laser is in operation so that a desired partial pressure of the halogen can be maintained.

Abstract: A laser having a roughened, catalytic surface to regenerate fluid within the lasing chamber that decomposes during operation of the laser. The roughness of this surface greatly increases its surface area thereby greatly increasing the rate of action of this catalytic surface in regenerating fluid. This structure is particularly useful in producing small, handheld CO.sub.2 lasers.

Abstract: Dust in a gas laser, particularly an excimer laser, is removed from the gas charge by one or more electrostatic precipitators that are located inside the laser vessel in the path of gas circulation that is produced by a fan and passes through the discharge area defined by the main discharge electrodes. The gas is caused to travel rapidly past the precipitator so that only a minor proportion of the dust is removed at each pass, but a low background level of dust in the gas is soon achieved and maintained by repeated such passes. This technique of employing multiple passes, each removing only a small percentage of the dust in the gas at any given time, can also be applied to a system in which the precipitator is located outside the vessel and is connected thereto by conduits.

Abstract: A modularized system for controlling the gas pressure within a copper vapor or like laser is described herein. This system includes a gas input assembly which serves to direct gas into the laser in a controlled manner in response to the pressure therein for maintaining the laser pressure at a particular value, for example 40 torr. The system also includes a gas output assembly including a vacuum pump and a capillary tube arrangement which operates within both a viscous flow region and a molecular flow region for drawing gas out of the laser in a controlled manner.