Coherent, Inc.

Lanny Laughman

Leon A Newman

Vernon A Seguin

Anthony J DeMaria

Adrian Papanide

John T Kennedy

Robert Henschke

Eric R Mueller

Richard A Hart

Joel Fontanella

Peter P Chenausky

Gongxue Hua

Thomas V Hennessey, Jr

Christian J Shackleton

Raymond Michaud

Ronald Straayer

James Hyland

Michael Leigh Ermold

Joseph S Smucz

A radio-frequency excited carbon dioxide (CO) or carbon monoxide (CO) gas laser includes two electrodes, which have passivated surfaces, within a sealed housing. Features in a ceramic slab or a ceramic cylinder located between the electrodes define a gain volume. Surfaces of the ceramic slab or the ceramic cylinder are separated from the passivated surfaces of the electrodes by small gaps to prevent abrasion thereof. Reducing compressive forces that secure these components within the housing further reduces abrasion, thereby extending the operational lifetime of the gas laser.

Radio-frequency excited gas laser

Laser-drilling apparatus includes a gas-discharge for laser emitting laser-radiation pulses, and two acousto-optic modulators (AOMs). The laser radiation pulses are characterized as having two temporal central portions between temporal leading and trailing edge portions. The AOMs are arranged to spatially separate the central temporal portions of the pulses from each other and from the leading and trailing edge portions of the pulses.

Pulse-dividing method and apparatus for a pulsed carbon monoxide laser

A carbon-dioxide (CO) gas-discharge slab laser includes elongated discharge-electrodes in a sealed enclosure. Radio Frequency (RF) power is supplied to the electrodes via an impedance matching network and a co-axial electrical low inductance transmission line feed-through sealed to the enclosure. The feed-trough includes two spring contacts which are configured to be spring compression push-fit in grooves in edges of the discharge-electrodes. A central conductor of the feed-through is fluid cooled. A capacitor of the impedance matching network is assembled on the central conductor as an integral part of the feed-trough.

Hermetically-sealed RF feed-through with integrated capacitor

A mirror assembly for a carbon dioxide (CO) slab laser resonator includes a center section having a rectangular cross-section and a pair of thermal balancing bars. A concave reflecting surface formed on a front edge of a center section. The side-bars are attached to either side of the center section and extend forward of the reflective surface. Dimensions of the center section and side bars are selected to position the thermal neutral plane of the assembly close to the reflective surface. This minimizes changes the radius of curvature of the reflective surface due to heating by circulating radiation in the resonator.

Compensation for transient heating of laser mirrors

A COgas discharge laser includes a housing enclosing spaced-apart electrodes and a lasing gas. A laser resonator extends between the spaced-apart electrodes. An RF power supply provides RF power for creating a discharge in the lasing gas, causing laser radiation to be delivered by the laser resonator. The power of the output radiation is directly dependent on the RF power provided to the electrodes and inversely dependent of the temperature of the gas discharge. A signal representative of the discharge-temperature is used to adjust the RF power supplied to the electrodes such that the power of the output radiation is about constant.

[object Object]

A laser mirror assembly is disclosed with improved pointing stability. An elongated mirror includes a concave reflecting portion. A pair of elongated planar portions extend parallel to the concave reflecting portion on either side thereof. The planar portions are stepped down from the reflecting portion. The mirror is formed from copper. A pair of stainless steel strips are connected to planar portions. The bimetallic effect between the copper mirror and the stainless steel strips operates to counteract the warping of the mirror due to differential heating effects which arise during operation. In an alternate embodiment, a pair of aluminum strips are mounted on the rear surface of the mirror.

Thermal distortion compensation for laser mirrors

Through the use of a relatively inexpensive third mirror on a novel folded hybrid unstable resonator configuration, the optimum output coupling for a given laser design can be explored quickly and easily with a minimum of intracavity mirror alignment. No changes in either the radii of curvature of the three cavity optics or their spacing are required for this exploration. In addition to providing techniques for purposefully and systematically introducing mirror edge effects or avoiding edges effects altogether, the invention provides that output beams of different width can be advantageously explored in a relatively simple and straightforward manner. The invention provides that higher geometric magnification cavity designs may be made compatible with low diffraction output coupling in a configuration that uses only three totally reflecting optics.

Unstable resonator with variable output coupling

An improved laser system includes a sealed-off, RF excited, diffusion cooled, high pressure, short pulsed, high peak power waveguide and slab COlaser that avoids problems typically associated with obtaining a diffused discharge at high gas pressures, without arcing and without corona, while maintaining the unsaturated gain and gas temperature experienced at low pressures and scaling to higher pressures. Such a system has a long operating life-time, and is capable of operation at high gas pressures to obtain relative fast rise and fall time pulses. The system emits relatively short pulse widths, with pulse energies up to and exceeding 30 mJ, with reasonably high pulse repetition rates. The system also has a low pulsed RF power duty cycle, thereby enabling the generation of high peak power pulses, as well as reasonable average power and reasonably high peak powers.

Various electro-optical modulator module designs are presented, which can provide for uniform, symmetric, and efficient heat removal for mode-locking, Q-switching, and/or cavity dumping operations. Heat can be uniformly extracted from an EO crystal without imposing undue stress, thereby preventing birefringence and laser beam degradation. A liquid-cooling approach can be used for high-duty operations, such as mode-locking operations. Efficient heat removal can prevent thermal run-away from electrical heating of the crystal due to the large drop in the electrical resistance of CdTe with increasing temperature when operated above 50&#xb0; C. RF or video arcing and subsequent damage to the EO crystal can be prevented by surrounding the crystal with a low dielectric constant material that lowers the capacitance coupling to ground, while still maintaining good thermal cooling.

This disclosure discusses techniques for obtaining wavelength selected simultaneously super pulsed Q-switched and cavity dumped laser pulses utilizing high optical damage threshold electro-optic modulators, maintaining a zero DC voltage bias on the CdTe electro-optic modulator (EOM) so as to minimize polarization variations depending on the location of the laser beam propagating through the CdSe EOM crystal, as well as the addition of one or more laser amplifiers in a compact package and the use of simultaneous gain switched, Q-switched and cavity dumped operation of COlasers for generating shorter pulses and higher peak power for the hole drilling, engraving and perforation applications.

Q-switched, cavity dumped laser systems for material processing

A waveguide gas laser includes an enclosure filled with a lasing gas. A ceramic block is provided with one or more waveguide channels. At least one of the waveguide channels includes an open region which is in fluid communication with a waveguide channel. Lasing gas in the enclosure fills the waveguide channels and the lateral extension. An electric field is applied across the lateral extension of the waveguide channel while simultaneously applying a smaller electric field across the waveguide channel. The electric field across the lateral extension ignites a discharge in the lateral extension that spreads into the lasing gas in the waveguide channel. The electric field across the waveguide channel is sufficient to sustain the discharge in the lasing in the waveguide channel.

A simultaneously super pulsed Q-switched CO laser system for material processing is disclosed. The system comprises sealed-off folded waveguides with folded mirrors that are thin film coated to select the output wavelength of the laser. The system also comprises a plurality of reflective devices defining a cavity; a gain medium positioned within the cavity for generating a laser beam; a cavity loss modulator for modulating the laser beam, generating thereby one or more laser pulses; a pulsed signal generation system connected to the cavity loss modulator for delivering pulsed signals to the cavity loss modulator thereby controlling the state of optical loss within the cavity; a control unit connected to the pulsed signal generation system for controlling the pulsed signal generation system; and a pulse clipping circuit receptive of a portion of the laser beam and connected to the pulsed signal generation system for truncating a part of the laser pulses.

Q-switched CO2 laser for material processing

A folded waveguide CO laser includes a plurality of waveguides arranged in a zigzag pattern with ends thereof overlapping. The laser includes a resonator having an axis extending through the plurality of waveguides. At least a portion of at least one of the waveguides has a uniform minimum width selected cooperative with the height of the waveguide and the laser wavelength such that the resonator can oscillate in only a single mode. At least a portion of one of the waveguides is tapered such that its width increases in one direction along the resonator axis. Tapering one or more of the waveguides provides that the total waveguide area and potential power output of the laser is greater than that of a zigzag arrangement of waveguides having the same total length waveguides each having a uniform width equal to the minimum width of the waveguide in the tapered waveguide arrangement.

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Bolton, CT, United States of America

Lanny Laughman