Coherent light generators – Particular pumping means – Electrical
Patent
1993-02-11
1994-09-13
Bovernick, Rodney B.
Coherent light generators
Particular pumping means
Electrical
372 57, H01S 3097
Patent
active
053475305
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a pulsed gas-discharge laser system, in particular a pulsed excimer laser system, comprising a resonator and a gas volume filled with laser gas in which a gas discharge is ignitable, a microwave discharge structure surrounding the gas volume at least partially for maintaining the gas discharge, a microwave source for generating a microwave pulse and a microwave line leading from the microwave source to the microwave discharge structure.
In these pulsed gas-discharge laser systems known, for example, from U.S. Pat. No. 4,802,183, the achievable laser pulse power is proportional to the microwave pumping power. For this reason, pulsed, microwave-pumped gas-discharge laser systems have so far been unable to achieve high powers.
The object underlying the invention is, therefore, to provide a microwave-pumped, pulsed gas-discharge laser system in which the laser pulse power behaves over-proportionally to the pumping power.
This object is accomplished in accordance with the invention with a pulsed gas-discharge laser system of the kind described at the beginning by there being coupled to the microwave line by a coupling element a resonant microwave storage structure which leads to the gas volume and extends with at least a partial section thereof between the microwave discharge structure and the microwave line, and by the microwave storage structure being of such design and coupled to the microwave line by the coupling element in such a way that it stores the energy from the microwave pulse emitted by the microwave source until the ignition of the gas discharge and after the ignition of the gas discharge maintains the latter with the stored energy.
The advantage of the present invention is to be seen in the fact that the microwave pulse can as it were be "compressed" and a power is thus available for the maintenance of the gas discharge which lies above the power of the microwave pulse of the microwave source by a factor of from approximately 10 to approximately 1000. Therefore, laser pulse powers which are comparable with TEA pumped lasers are achievable with conventional microwave sources.
To protect the microwave source, it has proven particularly advantageous for the microwave storage structure to be of such design and coupled to the microwave line by the coupling element in such a way that after the ignition of the gas discharge it couples back into the microwave line at most a microwave power which is double the microwave power of the microwave pulse. This means that in the present invention it is not a matter of coupling the microwave storage structure to the microwave line by the coupling element in such an optimum way that as much power as possible is stored in the microwave storage structure when the gas discharge is not ignited, but also of designing and coupling the microwave storage structure by the coupling element in such a way that when the gas discharge is ignited, the microwave power coupled back into the microwave line does not destroy the microwave source.
It is even more advantageous for the microwave storage structure to couple into the microwave line, after the ignition of the gas discharge, at most a microwave power which is 1.5 times the microwave power of the microwave pulse, and it is particularly advantageous for the coupled-back microwave power to correspond at most to the microwave power of the microwave pulse.
To achieve optimum coupling in the microwave discharge structure for maintenance of the gas discharge, provision is advantageously made for an electric field vector of the microwaves in the microwave discharge structure to stand perpendicular on an optical axis of the resonator. In this way, in particular, the coupling of the microwaves to the gas discharge can be optimized.
Furthermore, in order to achieve advantageous coupling of the microwaves for maintenance of the gas discharge, it is expedient for the region of the gas volume penetrated by the electric field in the microwave discharge structure to extend in the direction of the optical axis of th
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Gekat Frank
Klingenberg Hans
Krutina Gerhard
Bovernick Rodney B.
Deutsche Forschungsanstalt fuer Luft - und Raumfahrt e.V.
Lipsitz Barry R.
Wise Robert E.
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