Abstract: For increasing the laser damage threshold (LDT) of diffraction gratings, particularly of multi-layer dielectric diffraction (MLD) gratings, the invention proposes a method for treating a diffraction grating to be used in a high energy laser apparatus having a first laser with the steps of providing the diffraction grating, providing a second treatment laser and irradiating the diffraction grating with laser light from the second treatment laser until the laser damage threshold of the diffraction grating has increased. Furthermore, the invention proposes a diffraction grating treated according to the method, as well as a laser system, which comprises such a diffraction grating.

Abstract: For increasing the laser damage threshold (LDT) of diffraction gratings, particularly of multi-layer dielectric diffraction (MLD) gratings, the invention proposes a method for treating a diffraction grating to be used in a high energy laser apparatus having a first laser with the steps of providing the diffraction grating, providing a second treatment laser and irradiating the diffraction grating with laser light from the second treatment laser until the laser damage threshold of the diffraction grating has increased. Furthermore, the invention proposes a diffraction grating treated according to the method, as well as a laser system, which comprises such a diffraction grating.

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 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 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.