Carl-zeiss-stiftung

Wolfgang Rupp

Peter Greve

Martin Blumentritt

Alexander Hinz

In a process for the correction of non-rotationally-symmetrical image errors in an assembly, e.g., an objective with optical elements, particularly lenses, several Peltier elements are arranged on at least one of the optical elements, distributed over its periphery, and are differently driven electrically in order to act on the temperature distribution in the optical element. A respective temperature-conducting connection is provided between the Peltier elements and the optical element. The invention also relates to an objective with optical elements, particularly lenses, and Peltier elements.

Process for the correction of non-rotationally-symmetrical image errors

A gas laser 1 such as a .sup.13 CO.sub.2 -laser emits at two different wavelengths (.lambda..sub.1, .lambda..sub.2) with a sine-shaped adjustment of a resonator mirror or a grating 13 such as a Littrow grating. The gas laser emits radiation at the two desired wavelengths (.lambda..sub.1, .lambda..sub.2) in two mutually adjacent intervals of the resonator length L because of a suitable dimensioning of the grating 13 with respect to grating structure and angle position, the outcoupling factor of the outcoupling mirror 12, the resonator length L and the composition of the gas of the laser. The laser emission is inhibited at the crossover between the two intervals and the sine-shaped modulation (for example with a piezo element) of the resonator length L is essentially symmetrical about this crossover. The invention is also directed to an arrangement for detecting a substance such as NH.sub.3 in a flue gas. This arrangement includes a two wavelengths laser light source 1, a modulation unit 14 and a reference detection unit D1; a transmission optic 2; a measuring path 3 which contains the substance to be detected; a receiving optic 4 and a measuring detector D2. An evaluation apparatus 5 is also provided which determines the ratio of the light absorption in the measuring path 3 at the two wavelengths (.lambda..sub.1, .lambda..sub.2) and determines therefrom the concentration of the substance to be detected in the measuring path 3.

Gas laser for emitting light modulated at two different wavelengths and

The invention is directed to a laser arrangement for converting frequency wherein the fundamental frequency or the converted frequency can be selectively emitted by means of an optical element which can be pivoted into and out of the beam path. An especially slim configuration of the overall arrangement is obtained with the aid of an additional deflection element.

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Aalen, Germany

Wolfgang Rupp