Coherent light generators – Particular resonant cavity – Folded cavity
Reexamination Certificate
1998-09-14
2001-07-03
Kim, Robert H. (Department: 2877)
Coherent light generators
Particular resonant cavity
Folded cavity
Reexamination Certificate
active
06256332
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention:
The invention relates to a stripline laser.
Stripline or slab lasers are disclosed, for example, in U.S. Pat. No. 4,719,639 and U.S. Pat. No. 5,048,048. In the case of those lasers, an elongate narrow parallelepipedal discharge chamber for a gas, in particular CO
2
, is formed between planar electrodes which are parallel to one another. The gas is electrically excited by a radiofrequency voltage applied to the electrodes. In order to achieve a laser effect, resonator mirrors are disposed opposite rectangular end surfaces of the discharge chamber. Those resonator mirrors form a resonator only in a plane which is parallel to the electrodes, that is to say in the direction of the width of the discharge chamber. Transversely thereto, that is to say in the direction of the distance between the electrodes or the height of the discharge chamber, the two electrodes behave as waveguides.
U.S. Pat. No. 4,719,639 explains in further detail that both stable and unstable resonators are suitable. In particular, an unstable confocal resonator of the negative branch is proposed in U.S. Pat. No. 5,048,048.
Unstable resonators have a number of advantages which are important for high-power lasers, in particular. Thus, with unstable resonators it is possible, for example, to achieve high mode volumes and better utilization of the total volume region of the discharge chamber, that is to say of the entire excited gas, even in relatively short resonators. Compact high-power lasers can thus be built with the aid of unstable resonators.
However, unstable resonators have the property that the intensity distribution in the cross-section of the laser beam differs in the near-field and far-field range and that the far-field distribution moreover has, as a rule, secondary maxima which have to be filtered out by suitable devices.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a stripline laser, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which is distinguished by a high beam quality and a high laser power in conjunction with a compact overall structure of the laser.
With the foregoing and other objects in view there is provided, in accordance with the invention, a stripline laser, comprising two planar electrodes; a discharge chamber or space disposed between the two planar electrodes and having a longitudinal direction, a width and end surfaces oriented perpendicularly to the longitudinal direction; and a planar multipass resonator being associated with the end surfaces and being stable referring or relative to the width of the discharge chamber, the resonator having a folding mirror configuration within the resonator.
The use of a stable multipass resonator configuration having a resonator-internal folding mirror configuration ensures that, on one hand, the entire discharge chamber is utilized and that, on the other hand, the advantageous properties of the laser beam that are associated with the use of a stable resonator, are obtained. Those advantageous properties are, in particular, an intensity distribution over the beam cross-section that is virtually independent of the distance from the beam exit window, as well as the absence of interfering secondary maxima.
In accordance with another feature of the invention, the folding mirror configuration is a telescopic folding mirror configuration.
In accordance with a further feature of the invention, the telescopic folding mirror configuration has an optical axis running outside the discharge chamber.
In accordance with a concomitant feature of the invention, the telescopic folding mirror configuration includes a mirror associated with one of the end surfaces and having a reflecting surface curved convexly toward the discharge chamber; and a mirror facing the other of the end surfaces and having a reflecting surface curved concavely toward the discharge chamber.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a stripline laser, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
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Flores Ruiz Delma R.
Greenberg Laurence A.
Kim Robert H.
Lerner Herbert L.
Rofin-Sinar Laser GmbH
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