Abstract: A preionization device for a gas laser comprises an internal preionization electrode having a dielectric housing around it and an external preionization electrode displaced from the dielectric housing by a small gap. The dielectric housing includes two cylindrical regions of differing outer radii of curvature. An open end of the housing has a larger radius of curvature than the other end which is closed. The internal electrode connects to circuitry external to the discharge chamber via a conductive feedthrough which penetrates through the housing. The external circuitry prevents voltage oscillations caused by residual energy stored as capacitance in the dielectric housing. The external preionization electrode, which is connected electrically to one of the main discharge electrodes, is formed to shield the internal preionization electrode from the other main discharge electrode to prevent arcing therebetween.

Abstract: A laser for an excimer or molecular fluorine laser includes an electrode chamber connected with a gas flow vessel and having a pair of main electrodes and a preionization unit each connected to a discharge circuit. A spoiler is provided within the electrode chamber and is shaped to provide a more uniform gas flow through the discharge area between the main electrodes, to shield one of the preionization units from one of the main electrodes, and to reflect acoustic waves generated in the discharge area into the gas flow vessel for absorption therein. A spoiler unit may include a pair of opposed spoiler elements on either side of the discharge area. One or both main electrodes includes a base portion and a center portion which may be a nipple protruding from the base portion. The center portion substantially carries the periodic discharge current such that the discharge width is and may be significantly less than the width of the base portion.

Abstract: A laser for an excimer or molecular fluorine laser includes an electrode chamber connected with a gas flow vessel and having a pair of main electrodes and a preionization unit each connected to a discharge circuit. A spoiler is provided within the electrode chamber and is shaped to provide a more uniform gas flow through the discharge area between the main electrodes, to shield one of the preionization units from one of the main electrodes, and to reflect acoustic waves generated in the discharge area into the gas flow vessel for absorption therein. A spoiler unit may include a pair of opposed spoiler elements on either side of the discharge area. One or both main electrodes includes a base portion and a center portion which may be a nipple protruding from the base portion. The center portion substantially carries the periodic discharge current such that the discharge width is and may be significantly less than the width of the base portion.

Abstract: A wavelength calibration system determines an absolute wavelength of a narrowed spectral emission band of an excimer or molecular laser system. The system includes a module including an element which optically interacts with a component of an output beam of the laser within the tunable range of the laser system around the narrowed band. An inter-level resonance is detected by monitoring changes in voltage within the module, or photo-absorption is detected by photodetecting equipment. The absolute wavelength of the narrowed band is precisely determinable when the optical transitions occur and are detected. When the system specifically includes an ArF-excimer laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 193 nm and the element is preferably a gas or vapor selected from the group consisting of arsenic, carbon, oxygen, iron, gaseous hydrocarbons, halogenized hydrocarbons, carbon-contaminated inert gases, germanium and platinum vapor.

Abstract: A laser is provided having a gain medium including a laser gas and a photoabsorbing species. The photoabsorbing species has at least one photoabsorption line within an output emission spectrum of the laser. When the laser is an ArF-excimer laser, the photoabsorbing species is preferably either atomic carbon or molecular oxygen, which are formed after carbon- or oxygen-containing molecules introduced into the gain medium with the laser gas interact within the gain medium. An absolute wavelength of a narrowed emission of the laser can be calibrated when a narrowed output emission of the laser is tuned through at least one photoabsorption line of the photoabsorbing species. Preferably, a processor communicates with a detector and a wavelength selection unit, as well as a power supply when output beam energy is held constant, to automatically perform the calibration.

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 wavelength calibration system determines an absolute wavelength of a narrowed spectral emission band of an excimer or molecular laser system. The system includes a module including an element which optically interacts with a component of an output beam of the laser within the tunable range of the laser system around the narrowed band. An inter-level resonance is detected by monitoring changes in voltage within the module, or photo-absorption is detected by photodetecting equipment. The absolute wavelength of the narrowed band is precisely determinable when the optical transitions occur and are detected. When the system specifically includes an ArF-excimer laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 193 nm and the element is preferably a gas or vapor selected from the group consisting of arsenic, carbon, oxygen, iron, gaseous hydrocarbons, halogenized hydrocarbons, carbon-contaminated inert gases, germanium and platinum vapor.

Abstract: A molecular fluorine (F.sub.2) laser is provided wherein the gas mixture comprises molecular fluorine for generating a spectral emission including two or three closely spaced lines around 157 nm. An etalon provides line selection such that the output beam only includes one of these lines. The etalon may also serve to outcouple the beam and/or narrow the selected line. Alternatively, a prism provides the line selection and the etalon narrows the selected line. The etalon may be a resonator reflector which also selects a line, while another element outcouples the beam. The etalon plates, preferably uncoated, comprise a material that is transparent at 157 nm, such as CaF.sub.2, MgF.sub.2, LiF.sub.2, BaF.sub.2, SrF.sub.2, quartz and fluorine doped quartz. The etalon plates are separated by spacers comprising a material having a low thermal expansion constant, such as invar, zerodur.RTM., ultra low expansion glass, and quartz. A gas such as helium or a solid such as CaF.sub.

Abstract: Even in the case of variations in the pulse repetition frequency, a solid-state laser generates laser pulses with constant beam characteristics in such a way that when the pulse repetition frequency of the laser pulses is varied the pulse duty factor of the pumping radiation is kept constant and Q switching is triggered in each case at a prescribed period after the start of the pumping pulse.

Abstract: A solid state laser, especially a solid state laser pumped by laser diodes (3b, 3c) comprises a polarizing beam splitter (5) to couple out from the resonant cavity some part (11) of the radiation energy. An electro-optic modulator (Pockels' cell) (4) serving as couple-out modulator is adjusted such that the ratio of the pulse energy of the laser beam pulses (10) emitted to the coupled-out part (11) of the radiation energy is variable and thus the pulse energy is adjustable by keeping the pulse duration constant.

Abstract: The present invention is an apparatus and method for stabilization of laser output beam characteristics by automatically adjusting the angular and the lateral positions of the output beam. A component of the output beam is detected at a far field location and also at a near field location along an optical path of the component. Both the angular and the lateral positions of the output beam are determined, as well as characteristics of the output beam, after the component is detected at both the near and the far field locations. Both the angular position and the lateral position of the output beam are automatically adjusted to optimize the output beam. The adjustment of both the angular position and the lateral position are made possible by using a beam steering device preferably including two mirrors.

Abstract: A solid state laser is provided including a rare earth-doped YAG, YLF, YVO, GSGG, YALO or GdVO oscillator crystal, at least one laser diode pumping source, a Q-switch short pulse generator, a frequency doubling stage and frequency quadrupling or quintupling stages. The frequency quadrupling or quintupling stages include a nonlinear optical crystal such as CLBO, BBO or LBO built into a housing. The housing is sealed off to prevent external moisture and other atmospheric impurities from accessing the crystal at its interior. The housing interior is configured for purging with one or more external inert gases or dry air through valve controls. The housing is equipped with a mechanism for controlling the temperature of the interior of the housing, and consequently for controlling the temperature of the crystal. The temperature controlling mechanism enables heating and cooling of the crystal, as well as maintaining the crystal at a constant selected temperature.

Abstract: A laser system having a resonant cavity that is stable in one axis so that a wavelength selector can be used for producing a narrow line output, and is unstable in an orthogonal axis for high energy extraction efficiency and for low output beam divergence. The resonant cavity terminates at one end with a cylindrical mirror and at the other end with a dispersive wavelength selector. A gain medium is disposed in the resonant cavity, and is excited by a power supply to generate a laser beam that oscillates in the resonant cavity. A portion of the laser beam is coupled out of the resonant cavity as an output laser beam. The cylindrical mirror has a cylindrical reflecting surface oriented to diverge the laser beam at a first azimuthal angle relative to an axis of the resonant cavity. The dispersive wavelength selector disperses the laser beam as a function of wavelength at a second azimuthal angle relative to the resonant cavity axis. The second azimuthal angle is orthogonal to the first azimuthal angle.

Abstract: A source of narrow-band coherent radiation has a first optical parametric oscillator (OPO 1) for producing seed radiation, and a second optical parametric oscillator (OPO 2), into which the seed radiation is input after passing through a wavelength-selective element (G). In order to stabilize and adjust the bandwidth of the radiation (14) emitted by the second optical parametric oscillator (OPO 2), radiation of this type is also input into the wavelength-selective element (G) and thereby analyzed, in order, in accordance with the analysis, to adjust the wavelength-selective element or the OPO 2.

Abstract: A Q-switched solid-state laser has a narrow-band laser diode (18) whose narrow-band output radiation serves as seed radiation for exciting a solid (14), with the result that only a single wavelength-stable longitudinal mode oscillates in the resonator (10, 12) of the solid-state laser and corresponding radiation (16) is emitted.

Abstract: A laser arrangement for generating narrow-band, tunable coherent radiation has an optical parametric oscillator (10) and a tunable seed oscillator (20) whose emitted seed radiation can be set in a narrow-band fashion by means of at least one wavelength-selective element (30). In order to achieve simple tunability of the output radiation (38) of the OPO in conjunction with a narrow bandwidth, good spatial beam quality and high beam intensity without maladjustment of the OPO resonator, the lineshape, set using the wavelength-selective element (30), of the seed radiation I.sub.seed (.lambda.), and the intensity transmission function T.sub.opo, (.lambda.) of the non-pumped resonator (12, 14) of the OPO (10) are set in such a way that given tuning of the center wavelength .lambda..sub.max seed of the seed oscillator (20) in the middle between two neighboring transmission maxima of the intensity transmission function T.sub.opo (.lambda.) it holds for all wavelengths .lambda. not equal to .lambda..sub.

Abstract: A tunable source of narrowband coherent radiation comprises a pulsed pump laser (10), an optical parametric oscillator or amplifier (12) and a so-called master oscillator (14). The narrowband output radiation of the master oscillator serves as seed radiation which is injected into the optical parametric oscillator or amplifier (12). In order to obtain a beam profile of the emitted output radiation as homogeneous as possible, optically imaging elements (28) are arranged in an optical delay line (24) for the partial pulses which pump the optical parametric oscillator or amplifier, which transform the spatial beam profile at the output (30) of the pump laser (10) with respect to amplitude, phase and, preferably, the divergence, too, into the crystal of the optical parametric oscillator or amplifier.

Abstract: A tunable narrowband source of a coherent radiation, comprisinga first optical parametric oscillator (OPO1) which includes at least one first optical parametric amplifier medium (K.sub.1) in a resonator (18, 20; 20, 34) or an optical parametric generator;at least one second optical parametric oscillator (OPO2) which includes at least one second optical parametric amplifier medium (K.sub.

Abstract: A tunable, optical, parametric oscillator including at least one non-linear optical crystal (10) comprises a first deflector mirror (18) arranged inside the resonator between the resonator mirror (12) and the crystal (10) to couple in the pump radiation (16) as well as a second deflector mirror (20) arranged outside the resonator behind a second resonator mirror (14) to separate the pump radiation (22) from the radiation (24) generated in the optical parametric oscillator.

Abstract: A tunable narrowband optical parametrical oscillator (OPO) is excited in pulsed fashion to generate tunable narrowband radiation. A wavelength selective means (T, G) disposed outside the resonant cavity (M3, M4) of the optical parametrical oscillator reduces the bandwidth of the OPO radiation generated. A pumping pulse is divided by a beam splitter (DM1) into at least two partial pulses, and the delay between the two partial pulses is adjusted by means of a delay distance (D) in such a mannner that the first partial pulse will pump the crystal of the optical parametrical oscillator, part of the OPO radiation thus generated passing through the wavelength selective means which is arranged outside the resonant cavity, being coupled back into the resonant cavity, and passing through the crystal (C) once again when the second partial pulse (2) pumps the crystal (C).