Coherent, Inc.

Phillip J Gardner

Joseph L Dallarosa

John T Kennedy

Christian J Shackleton

Anthony J DeMaria

Vernon A Seguin

James L Hobart

J Michael Yarborough

Leon A Newman

Wayne S Mefferd

Joel Fontanella

William Clayton Brand

Donald E Smith

Raul Wong Gutierrez

The quality of pulses output from laser systems such as super-pulsed COslab lasers can be improved using half-wavelength electro-optic modulators (EOMs), in combination with thin film polarizers (TFPs). A voltage applied across a CdTe crystal of the EOM rotates the polarization of a pulse passing through the EOM by 90&#xb0;. The polarization determines whether the pulse passes through, or is redirected by, the TFP. The voltage applied to the crystal can be pulsed to prevent a drop in charge, which could allow radiation to leak to the application. A totem pole switch used to apply voltage to the EOM can receive a pulsed voltage for improved performance. Directing by the EOM allows pulses to be clipped at the front/back end(s), split into portions, and/or directed to separate scanners. Directing pulses or pulse portions to different scanners can increase the output of systems such as hole drilling systems.

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A slab laser includes two elongated electrodes arranged spaced apart and face-to-face. Either one or two slabs of a solid dielectric material extend along the length of the electrodes between the electrodes. A discharge gap is formed either between one of the electrodes and one dielectric slab, or between two dielectric slabs. The discharge gap is filled with lasing gas. A pair of mirrors is configured and arranged to define a laser resonator extending through the gap. An RF potential is applied across the electrodes creating a gas discharge in the gap, and causing laser radiation to circulate in the resonator. Inserting dielectric material between the electrodes increases the resistance-capacitance (RC) time constant of the discharge structure compared with the RC time constant in the absence of dielectric material. This hinders the formation of arcs in the discharge, which enables the laser to operate with higher excitation power, higher lasing gas pressure, and higher output power than would be possible without the dielectric inserts.

An slab CO2 laser includes spaced-apart elongated slab electrodes. A lasing gas fills a discharge gap between the electrodes. An RF power supply is connected across the electrodes and sustains an electrical discharge in the lasing gas in the discharge gap. Either one or two ceramic inserts occupy a portion of width of the electrodes and in contact with the electrodes. A discharge gap is formed between the portions of the width of the electrodes not occupied by the insert or inserts. Provision of the ceramic insert or inserts increases the resistance-capacitance (RC) time constant of the electrode impedance by increasing the capacitive component of the time constant. This hinders the formation of arcs in the discharge, which, in turn enables the inventive laser to operate with higher excitation power or higher lasing-gas pressure than would be possible without the dielectric insert. The ceramic insert also decreases the difference in impedance of the electrodes with and without a discharge. This leads to a better-behaved discharge, and a discharge that is easier to light.

A pre-ionizing arrangement for a gas laser includes two ceramic-jacketed ionizer electrodes extending into an enclosure including spaced-apart slab electrodes of the laser and a lasing gas at reduced pressure. RF power is applied to the dielectric-jacketed ionizer electrodes creating a gas discharge between the dielectric-jacketed ionizer electrodes. This discharge provides ions in the laser gas. The presence of these ions in the lasing gas facilitates ignition of a gas discharge between the slab electrodes for energizing the laser.

Pre-ionizer for RF-energized gas 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. 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. The subject laser is capable of generating high energy short duration pulses which can be used to treat tissue with reduced trauma.

Resonator for CO.sub.2 slab waveguide laser

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 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. 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. Finally, a lamp (110) is provided for preionizing the discharge to faciliate starting.

RF excited CO.sub.2 slab waveguide laser

A CO.sub.2 slab waveguide laser (10) disclosed including a pair of spaced apart electrodes (36,38) having exposed 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.

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West Hartford, CT, United States of America

Phillip J Gardner