Coherent light generators – Particular pumping means – Pumping with optical or radiant energy
Reexamination Certificate
2001-02-02
2002-08-20
Scott, Jr., Leon (Department: 2828)
Coherent light generators
Particular pumping means
Pumping with optical or radiant energy
Reexamination Certificate
active
06438152
ABSTRACT:
The invention relates to a laser amplification system comprising several solid-state volumes having a laser-active medium, a pumping radiation source for generating a pumping radiation field for the optical pumping of the laser-active medium, a pumping radiation reflector which is associated with each solid-state volume and allows a leg of the pumping radiation field entering the solid-state volume to pass through the solid-state volume again as an outgoing leg such that the incoming leg and the outgoing leg form an angle with one another located in a plane and thereby form a first pumping branch, a first pumping radiation path through the solid-state volumes, in which the first pumping branches are arranged so as to follow one another such that the pumping radiation field passes through the several solid-state volumes in a first sequence.
Laser amplification systems of this type are known, for example, from EP 0 632 551.
In the case of laser amplification systems with solid-state volumes having a laser-active medium the problem exists that a pumping light excitation of the individual solid-state bodies is brought about with varying pumping power.
The object underlying the invention is therefore to provide a laser amplification system with several solid-state volumes, with which the individual solid-state volumes are acted upon with pumping power as uniformly as possible.
This object is accomplished in accordance with the invention, in a laser amplification system of the type described at the outset, in that each solid-state volume is penetrated by a second pumping branch, the incoming leg of which and the outgoing leg of which are located in a second plane different to the first plane and in this form an angle with one another, that a second pumping radiation path is provided, in which the second pumping branches of the several solid-state volumes are arranged so as to follow one another such that the pumping radiation field passes through the solid-state volumes in a second sequence.
The advantage of the inventive solution is to be seen in the fact that with the second pumping radiation path the possibility is created of pumping each of the solid-state volumes with the same number of pumping branches and, in addition, of introducing the pumping power in the solid-state volumes to be pumped as uniformly as possible on account of the fact that the two pumping branches are located in different planes.
This has the advantage, in particular, with a view to the type of thin, disk-shaped solid-state bodies, which are provided in the inventive solution and are preferably located with a flat side on a cooling surface, that, as a result, the design of as uniform a temperature curve as possible with planes of essentially the same temperature extending parallel to the flat sides of the solid-state bodies is facilitated which is essential for the advantageous working within the scope of the inventive concept.
It is particularly favorable when in the second sequence the order of the solid-state bodies is changed in relation to the first sequence. This solution allows the reduction in intensity in the sequence to be counteracted as a result of the changed order.
With respect to the type of supply to the first and second pumping radiation paths, no further details have so far been given. One advantageous embodiment, for example, provides for each of the pumping light radiation paths to be supplied by its own pumping radiation source, wherein it is preferably provided for the pumping radiation sources to have essentially the same power.
Another alternative embodiment provides for the pumping radiation paths to be supplied by a single pumping radiation source. This has the advantage that—insofar as the radiation power of a single pumping radiation source is sufficient—this can be used for both pumping radiation paths.
In this respect, there are different possibilities for realizing the supply to the two pumping radiation paths with one pumping radiation source.
One possibility is for the pumping radiation field from the pumping radiation source to be divided between the two pumping radiation paths by a beam divider.
This solution has the advantage that, as a result, the possibility exists of supplying both pumping radiation paths with pumping radiation fields of essentially the same intensity.
Another advantageous solution provides for the pumping radiation paths to be coupled to one another by an optical deflection means, i.e. for the pumping radiation field to be coupled in by an optical deflection means with the intensity which is present at the end of one of the pumping radiation paths such that this supplies the next pumping radiation path. This solution is particularly expedient when the intensity absorbed per pumping radiation path is not very large and so following the first pumping radiation path a power of the pumping radiation field is nevertheless available which is sufficiently large to supply the second pumping radiation path.
In principle, it is provided within the scope of the inventive solution for the pumping radiation field to pass through each pumping radiation path in one direction. To improve the pumping of the solid-state bodies it is, however, also advantageous when the pumping radiation field passes through each pumping radiation path in two opposite direction. This is irrespective of whether two pumping radiation sources are provided for supplying the pumping radiation paths or only one pumping radiation source, the power of which can be coupled into the pumping radiation paths in the different ways already described.
A solution, which is particularly simple to realize and with which the pumping radiation field passes through each pumping radiation path twice, provides for a reflector to be arranged at one end of each pumping radiation path and for this to reflect back the pumping radiation field exiting from the pumping radiation path.
In conjunction with the preceding solutions it has merely been specified that the order of the solid-state volumes in the second sequence is intended to be different to that in the first sequence. This may be realized in the most varied of ways, in particular, in a different manner when not only a first sequence and a second sequence are provided but rather several sequences exceeding the first and the second sequences. In the simplest case of a first and a second sequence it is, however, preferably provided for the order of the solid-state volumes in the second sequence to be reversed in relation to the first sequence.
So far, it has been specified in conjunction with the inventive solution that there is a first pumping radiation path and a second pumping radiation path. The inventive solution is, however, not limited to two pumping radiation paths with first and second pumping branches, respectively. On the contrary, it is possible in a further inventive solution for at least one additional pumping radiation path to be provided, with which the pumping radiation field passes through the solid-state bodies in the form of at least one additional sequence. The advantage of this solution is to be seen in the fact that with it an even more uniform excitation of the solid-state bodies can be realized.
This may be realized particularly favorably when the at least one additional sequence runs such that this counteracts varying pumping excitations of the laser-active material in the solid-state volume as a result of the first and the second sequences.
It is, in particular, advantageous when the number of pumping radiation paths is an even number so that the fact that with each pumping radiation path the pumping radiation field pumps from the one pumping branch to the other pumping branch with lower power can be compensated particularly favorably.
With respect to the manner, in which the individual pumping branches of one pumping radiation path are coupled, no particular details have been given. One advantageous embodiment, for example, provides for the individual pumping branches of a pumping radiation path to be coupled by optical refocusin
Contag Karsten
Erhard Steffen
Giesen Adolf
Karszewski Martin
Stewen Christian
Lipsitz Barry R.
Universitaet Stuttgart Institut fuer Strahlwerkzeuge
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