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 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 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).

Abstract: For stabilizing the frequency of a narrow-band Excimer laser beam the interference rings of a Fabry-Perot interferometer 16 are projected onto a solid-state image sensor 18 and by means of the solid-state image sensor an electrical signal is generated which is dependent on the frequency of the laser beam. The electrical signal is compared with a stored reference signal to derive an adjusting signal 32 for an optical reflection grating 38 with which the frequency of the laser beam 12 is regulated to a desired value. The absolute value of the frequency of the laser beam 12 is determined by means of the optogalvanic effect.