Coherent light generators – Particular active media – Gas
Reexamination Certificate
2000-05-05
2003-09-02
Ip, Paul (Department: 2828)
Coherent light generators
Particular active media
Gas
C372S066000, C372S087000, C372S039000
Reexamination Certificate
active
06614826
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to systems and methods for tailoring transverse profiles of laser beams, and more particularly, to internally incorporating the systems and methods for tailoring transverse profiles of laser beams into resonator cavities and gain media of the lasers.
BACKGROUND OF THE INVENTION
Considerable efforts have been undertaken to improve the performance of lasers with particular attention to physical size, cost, efficiency and device complexity. A prime consideration in achieving these desirable characteristics is that lasers make efficient use of their discharge gain medium.
Conventional methods have included use of optical telescopes inside or outside optical cavities, but these tend to be complex and costly. Other efforts have focused on so-called large-area discharge or slab type lasers to increase efficiencies. These lasers typically have a gain medium
4
disposed between first and second reflector systems
6
a
and
6
b
forming a hybrid resonator configuration that is stable in a first dimension, such as the y-axis dimension of
FIG. 1
, with their gain medium having a narrow thickness in the first dimension to provide waveguide effects. These lasers further typically have an unstable resonator configuration in a second dimension with their gain medium
4
having a wider thickness in the second dimension, such as the x-axis dimension of
FIG. 1
, to provide free space effects. Both the first and second dimensions generally form a plane transverse to the laser beam path.
Further efforts have been directed at thermal expansion or distortion of key laser components, alignment stability of optical components, improving efficiencies related to size of the gain medium, and using additional mirrors to improve power stability and decrease effects of mirror defects.
Unfortunately, these and other conventional systems and methods share a common problem in that output beams obtained are asymmetrical (usually rectangular or elliptical) and often astigmatic with respect to the plane that is transverse to the laser beam path, such as depicted by the illustrative example of a cross-section of an output laser beam shown in FIG.
1
B. Consequently, undesired beam artifacts can occur, such as beam ellipticity, astigmatism, and the presence of a significantly non-Gaussian profile in some transverse beam planes during propagation away from the conventional lasers. These undesired beam artifacts can adversely impact the utility of these conventional systems and methods.
Attempts have been made to address this beam artifact dilemma. For instance, a resonator that is free space in both transverse directions has been used, but requires such a large inter-electrode gap that overall performance greatly suffers. Other attempts take advantage of a low frequency RF drive voltage, however, still promote the extraction of a high aspect ratio, transversely asymmetrical output beam, which suffers from the aforementioned shortcomings.
Given the limited results of prior attempts, conventional wisdom has come to accept that high efficiency configurations of large-area discharge lasers have an undesirable aspect of high aspect ratio, transversely asymmetrical output beams. Those conventionally minded expect that these output beams require reformatting such as to have circular transverse cross-sections, such as depicted by the illustrative example of a cross-section of an output laser beam shown in
FIG. 1C. A
conventional implementation typically employs a cylindrical optical telescope immediately following the laser output aperture to form a laser beam having a symmetrical cross-section transverse to the beam path. Unfortunately, these conventional remedies add further manufacturing costs and complexity, which would be better avoided if possible.
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Bethel Jason W.
Broderick Jeffery A.
Yelden Eugene F.
Davis , Wright, Tremaine, LLP
Ip Paul
Johnson Brian L.
Menefee James
Rondeau, Jr. George C.
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