Coherent, Inc.

Coherent Radiation

Wayne S Mefferd

James L Hobart

Michael W Sasnett

Joseph L Dallarosa

Peter N Allen

Bruce Peuse

Juan L Chilla

Richard J Saunders

Phillip J Gardner

William P Kolb

Donald E Smith

A laser-resonator terminated by two end mirrors is folded by a plurality of OPS-structures and a plurality of fold-mirrors. The OPS-structures are energized by focused radiation from diode-laser bars. The fold-mirrors are configured and arranged with respect to the OPS-structures and the end-mirrors such that a beam of laser radiation circulating in the resonator has about the same dimensions on each OPS-structure.

Optically pumped external-cavity semiconductor laser with multiple gain structures

A laser system is disclosed which is capable of selectively generating radiation at two competing wavelength regions. A gas discharge tube is provided which includes krypton as the lasing medium. A primary mirror is mounted at one of the tube. A switchable mirror assembly is mounted at the other end of the tube. The mirror assembly includes a frame. A cradle is pivotally mounted in the frame and is rotatable between two angular positions. A pair of mirrors are mounted to the cradle in a manner such for each of the two angular positions of the cradle, one of the two mirrors is in optical alignment with discharge tube. Each of the mirrors is provided with a wavelength selective coating which permits operation of the laser at different wavelengths. In the preferred embodiment used for ophthalmic applications, the laser can selectively generate red light or light in the yellow/green regime.

Laser system selectively operable at two competing wavelengths

A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in the waveguide dimension but the mirror spacing from the end of the guide is based in part on the configuration of the unstable resonator. A unique support structure is disclosed for maintaining the electrodes in a spaced apart orientation without confining the discharge. Further refinements are disclosed for cooling the laser and for accommodating thermal expansion of the parts. Finally, an improved adjustable mirror assembly (26,28) is provided which allows the tilt angle of the mirror to be varied from outside of the housing.

RF excited CO.sub.2 slab waveguide laser

A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in the waveguide dimension but the mirror spacing from the end of the guide is based in part on the configuration of the unstable resonator. A unique support structure is disclosed for maintaining the electrodes in a spaced apart orientation without confining the discharge. Further refinements are disclosed for cooling the laser and for accommodating thermal expansion of the parts. Finally, an improved adjustable mirror assembly (26, 28) is provided which allows the tilt angle of the mirror to be varied from outside of the housing.

A CO.sub.2 slab laser is disclosed having a pair of spaced apart electrodes defining a rectangular discharge region. RF energy is fed through the electrodes to excite the CO.sub.2 gas. A pair of mirrors are located adjacent the electrodes to define the resonant cavity. A recombinant surface is placed between the ends of the electrodes and the mirrors to quench oxidizing species generated by the discharge before they reach the mirrors. In this manner, the degradation of the mirrors is reduced so that the high power performance of the laser can be maintained. The recombinant surfaces can be defined by forming extension regions at the end of the electrodes between which the discharge is minimized. Alternatively, a mirror shield having a beam transmitting aperture can be used to quench the oxidizing species.

Slab laser with enhanced lifetime

A laser system employing one or more mirror sets having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, for example, to compensate for thermally-induced distributed lensing. In one class of preferred embodiments, the invention is a high power gas laser system having a folded optical cavity with a periodic intracavity refocusing means to compensate for distributed negative thermal lensing in the hot plasma that comprises the active medium, and thus maintain a substantially constant beam diameter throughout the optical cavity. The periodic intracavity refocusing means preferably includes a corner mirror set (including at least one curved mirror and at least one other mirror) at each corner of the folded optical cavity. In one preferred embodiment, each corner mirror set is a mirror pair including a spherical mirror and cylindrical mirror. In another preferred embodiment, each corner mirror set comprises three mirrors (including three spherical mirrors, or two spherical mirrors and a planar mirror). In another class of preferred embodiments, the inventive focusing mirror sets are not included within the optical cavity of a high power laser, but instead, one or more such focusing mirror sets are included within the output beam delivery optical components of a high power laser. For example, one of the inventive focusing mirror sets may replace a conventional lens to direct the output beam of a high power laser system along a desired path and maintain a desired beam diameter.

High power laser with focusing mirror sets

A servo alignment method and apparatus for maintaining laser beam alignment. An operating parameter of the laser (such as output beam power) is measured, and error signals are generated from the measured operating parameter signal for controlling the laser beam alignment. In one class of embodiments, modulation signals are supplied to an intra-cavity component of a laser system to modulate the beam path. The beam path may be modulated by reciprocating a laser resonator mirror about a mirror axis or two substantially orthogonal mirror axes. In the latter case, the mirror may be vibrated about the axes either alternately (first about one axis and then about the other) or simultaneously. In embodiments in which an intra-cavity component is modulated, the laser operating parameter is measured during such modulation, the measured operating parameter signal is demodulated (preferably by multiplication in a mixer with a selected frequency component of the modulation signal currently being asserted, and error signals are generated from the demodulated signal for controlling the laser beam alignment.

Laser alignment servo method and apparatus

A laser system employing one or more mirror sets having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, for example, to compensate for thermally-induced distributed lensing. In one class of preferred embodiments, the invention is a high power gas laser system having a folded optical cavity with a periodic intracavity refocusing means to compensate for distributed negative thermal lensing in the hot plasma that comprises the active medium, and thus maintain a substantially constant beam diameter throughout the optical cavity. The periodic intracavity refocusing means preferably includes a corner mirror set (including at least one curved mirror and at least one other mirror) at each corner of the folded optical cavity. In one preferred embodiment, each corner mirror set is a mirror pair including a spherical mirror and cylindrical mirror. In another preferred embodiment, each corner mirror set comprises three mirrors (including three spherical mirrors, or two sperical mirrors and a planar mirror). In another class of preferred embodiments, the inventive focusing mirror sets are not included within the optical cavity of a high power laser, but instead, one or more such focusing mirror sets are included within the output beam delivery optical components of a high-power laser. For example, one of the inventive focusing mirror sets may replace a conventional lens to direct the output beam of a high power laser system along a desired path and maintain a desired beam diameter.

The subject invention relates to a laser system where the length stability of the resonant cavity is important. Three unique mounting assemblies are disclosed to improve the stability of the cavity. The first assembly relates to a kinematic support for mounting an Invar bar. The second assembly defines a once-piece gimbal pivot ring designed to mount laser mirrors. The final aspect of the invention includes a mounting assembly designed to automatically compensate for changes in length of an Invar support bar due to temperature variations which could alter the cavity length of the laser.

Kinematic resonator support

A servo alignment method and apparatus for maintaining laser beam alignment. An operating parameter of the laser (such as output beam power) is measured, and error signals are generated from the measured operating parameter signal for controlling the laser beam alignment. In one class of embodiments, modulation signals are supplied to an intra-cavity component of a laser system to modulated the beam path. The beam path may be modulated by reciprocating a laser resonator mirror about a mirror axis or two substantially orthogonal mirror axes. In the latter case, the mirror may be vibrated about the axes either alternately (first about one axis and then about the other) or simultaneously. In embodiments in which an intra-cavity component is modulated, the laser operating parameter is measured during such modulation, the measured operating parameter signal is demodulated (preferably by multiplication in a mixer with a selected frequency component of the modulation signal currently being asserted), and error signals are generated from the demodulated signal for controlling the laser beam alignment.

The subject invention relates to a laser system where the length stability of the resonant cavity is important. Three unique mouning assemblies are disclosed to improve the stability of the cavity. The first assembly relates to a kinematic support for mounting an Invar bar. The second assembly defines a once-piece gimbal pivot ring designed to mount laser mirrors. The final aspect of the invention includes a mounting assembly designed to automatically compensate for changes in length of an Invar support bar due to temperature variations which could alter the cavity length of the laser.

The subject invention is related to a new and improved bore assembly for use with a gaseous ion laser. Each bore assembly is mountable to a heat conducting member located within the tube. The heat conducting member is provided with a central opening and is connected at the periphery thereof to the inner surface of the tube. The bore assembly of the subject invention includes a discharge confining element having a central channel and formed from a sputter-resistant material such as graphite. An outer support member is provided which is disposed about at least a portion of the discharge confining element and is brazed to the heat conducting member in a manner to mechanically constrain the discharge confining element. During assembly, the opening of the channels of the discharge confining elements are coaxially aligned. During operation of the laser, the mechanically constrained discharge confining element will be heated and expand radially into the outer support member until thermal equilibrium is achieved thereby defining a thermally conductive pathway for cooling the laser.

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Los Altos Hills, CA, United States of America

Wayne S Mefferd