Coherent, Inc.

United Technologies Corporation

Other

Demaria Electrooptics Systems, Inc.

Leon A Newman

John T Kennedy

Richard A Hart

Lanny Laughman

Vernon A Seguin

Anthony J DeMaria

Adrian Papanide

Joel Fontanella

Peter P Chenausky

Christian J Shackleton

Frederick T Olender

Robert Henschke

Thomas V Hennessey, Jr

Bernard A Woody

Gerald Meltz

Gary A Ball

Eric R Mueller

Frederick W Hauer

James R Dunphy

R Russel Austin

Hisashi Matsumoto

Gongxue Hua

Richard S Harris

William W Morey

Phillip J Gardner

Corey M Dunsky

Erroll H Drinkwater

W Shef Robotham, Jr

Martin C Foster

Archie D Heath

James Hyland

Michael Leigh Ermold

Vernon Sequin

Mathew David Rzewnicki

Kennedy, Jr John T

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

A compact COslab-laser is contained in a fluid cooled housing having three compartments. One compartment houses discharge electrodes and a laser resonator. Another compartment houses a radio-frequency power supply (RFPS) assembled on a fluid-cooled chill plate and an impedance-matching network. The remaining compartment houses beam-conditioning optics including a spatial filter. The housing and RFPS chill-plate are on a common coolant-fluid circuit having a single input and a single output. The spatial filter is optionally fluid-coolable on the common coolant fluid circuit.

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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 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

The laser tube housing of a COslab laser is provided with a cooling system in which coolant fluid tubes are inserted into hollowed out portions formed in the longitudinal sidewalls of the laser tube housing; mounting the coolant fluid tubes in this way provides for enhanced cooling and increased stiffness of the laser tube housing. Also, a cooling system is provided for the laser's electrode assembly that relies on a manifold system that is mounted on a longitudinal sidewall of the laser tube housing to route coolant fluid through the sidewall to the electrode assembly; sidewall flow of the coolant fluid enables the end flanges of the laser tube housing to be remove without disturbing either the electrodes or the optical resonator of the laser. Also, a bracket assembly is provided for attaching the laser's electrode assembly to a longitudinal sidewall of the laser tube housing; the bracket assembly includes two brackets each of which is attached to a respective end of the electrode assembly and each of which is also attached to a longitudinal sidewall of the laser tube housing in proximity to a respective longitudinal end of the laser tube housing.

An RF impedance-matching transformer for matching the output impedance of an RF amplifier to the discharge of a gas-discharge laser includes upper and lower dielectric plates arranged face-to-face and bonded together. A primary U-shaped strip winding is embedded in the bonded surface of one of the dielectric plates. A secondary strip-winding is formed on an exposed surface of the upper dielectric plates. A ground-plane electrode formed on an exposed surface of the lower dielectric plate. An electrical connector connects one end of the secondary strip-winding to the ground-plane electrode via a via-hole extending through the dielectric plates. The other end of the secondary strip-winding can be connected to the laser.

Transformer for impedance-matching power output of RF amplifier to gas-laser discharge

A RF shielded, series inductor, high power impedance matching network interconnector is provided for connecting an RF power supply to electrodes contained in the shielded, hermetically sealed laser tube housing of a slab laser system. The impedance matching interconnector comprises a short length of co-axial conductor and an impedance matching network that includes two L shaped networks. The inner conductor of the co-axial conductor is connected between the power supply output and the impedance matching network. The outer conductor of the co-axial conductor is grounded. The co-axial conductor has an impedance characteristic to match the power supply output impedance. The first L-shaped network includes a first inductor having a first end connected to the inner conductor of the co-axial conductor and a first capacitor connected to the second end of the first inductor and a second plate connected to ground. The second L shaped network includes a second inductor having a first end connected to the common connection between the second end of the first inductor and the first plate of the first capacitor and a second capacitor having a first plate connected to the second end of the second inductor and a second plate connected to ground. The common connection between the second end of the second inductor and the first plate of the second capacitor is connected through the shielded, hermetically sealed laser tube housing to the electrodes of the slab laser system. The two L-shaped networks may be implemented in a 'single capacitor' configuration for lower power applications or in a 'multi-capacitor' configuration for higher power applications.

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.

Multiple laser beams, each having a shape such as a Gaussian profile, can be incoherently combined to obtain a shaped, flat top laser beam. The combined laser beams can provide power levels necessary for material processing applications such as annealing, drilling, and cutting, while minimizing the amount of unused power. The lasers can be positioned in an array in order to shape the flat top beam, and can be staggered in position where necessary to give each output beam an equal beam path length. The relative frequencies and/or powers of the lasers can be adjusted to control the flatness and stability of the incoherently combined beam.

Systems and methods for forming a laser beam having a flat top

An electro-optical switch includes an optical assembly arranged to transmit laser-radiation. The optical assembly comprises an active optical crystal. On one of two opposite surfaces of the crystal is an optical window formed from a material having a refractive index lower than the material of the crystal. Heat deposited, as a result of transmission of the laser-radiation, at the surface of the crystal in contact with the widow is transferred to the window, thereby reducing the potential for optical damage to the crystal surface. The window is sufficiently thick that it has an odd integer multiple of quarter-wavelengths optical thickness at a wavelength about equal to a wavelength of the laser-radiation, thereby behaving as an antireflection device for the crystal at that wavelength. In one embodiment of the optical assembly, the active optical crystal is a cadmium telluride crystal and the window is formed from cesium bromide.

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.

Growing community of inventors

Glastonbury, CT, United States of America

Leon A Newman