General Electric Company

Lockheed Martin Coherent Technologies, Inc.

Josef Robert Unternahrer

Phillip Randall Staver

John L August, Jr

William Taylor Lotshaw

Mark J Kukla

Farzin Homayoun Azad

Ertugrul Berkcan

Jerome Johnson Tiemann

Marshall Gordon Jones

Thomas James Batzinger

Robert S Gilmore

Joseph Lucian Smolenski

Emilie Thorbjorg Saulnier

Carl Edward Erikson

Joseph P Chernoch

Iain T McKinnie

Scott E Christensen

Michael Francis X Gigliotti, Jr

John E Koroshetz

A passive Q-switch element is disclosed that permits operating a laser with a variable pulse repetition frequency (PRF). The Q-switch comprises two wedges of material, one made from saturable absorber material, the other from transparent material, with the two wedges mounted together to form a constant optical thickness block. By translating the block transversely to a laser beam the amount of saturable absorber material seen by the laser beam is altered and as a result the PRF of the laser is varied.

Variable pulse repetition frequency passively Q-switched laser

A system for transmitting the spatial profile of laser beams with particular applicability to coherently combine laser beams into one beam. The system includes a tapered waveguide with an inlet and outlet at ends of two waveguide elements each having a reflective surface facing into the waveguide. The reflective surfaces are non-parallel such that the inlet height is different than the outlet height, e.g., inlet height greater than outlet height. The system includes a beam input assembly controlling phases of laser beams input at the waveguide inlet, and the phases of the beams are locked to a substantially single phase. The waveguide length is selected to produce at the waveguide outlet a coherently combined laser beam from the input beams. The beam input assembly includes a laser beam source, a beam splitter generating lower power beams from source beams, and phase adjusters for controlling the phase of each input beam.

Laser beam transformation and combination using tapered waveguides

A method for laser shock peening a surface is disclosed. A laser beam pulse from a laser apparatus is produced. The laser pulse has a cross-section taken perpendicular to the laser beam, a fluence profile across the cross-section. The pulse against an area on said surface. The fluence profile is controlled such that process induced defects are reduced.

Laser shock peening method and apparatus

A method and apparatus of selecting a predetermined number of pulses from a stream of laser pulses is described. The number of pulses is determined by the operator from the laser pulse repetition rate and the desired number of pulses. The invention comprises synchronizing the laser pulses with the start of the pulse selection, allowing the predetermined count of laser pulses to pass a blocking mechanism; and finally blocking the pulses after the pulses have passed.

Method and apparatus to select a predetermined number of pulses from a laser

A target is laser shock peened by directing against an ablative coating thereon a laser beam pulse having a fluence, duration, and corresponding peak power effective for ablating the coating to form a plasma and shock wave therein. The plasma is confined adjacent the target to plastically deform the target by the shock wave to develop residual compressive stress therein. The pulse has a duration less than ten nanoseconds and a corresponding peak power for increasing coupling efficiency between the pulse and plasma.

Short-pulse high-peak laser shock peening

A method and apparatus for sensing properties of glass-ceramic cooktop appliance having at least one burner assembly disposed under a glass-ceramic plate. The sensor assembly includes a waveguide having a first end disposed in the burner assembly and a second end disposed outside of the burner assembly, and at least one detector located adjacent to the waveguide's second end. A radiation collector is located adjacent to the first end of the waveguide so as to direct incident radiation substantially paraxially into the waveguide. The method includes collecting radiation from the glass-ceramic plate, and directing the collected radiation onto a detector located outside of the burner assembly via a waveguide.

Method and apparatus for sensing properties of glass-ceramic cooktop

A circulating laser beam is generated in an oscillator having a gain medium. The laser beam is dumped from the oscillator to produce a laser beam pulse. The laser beam pulse is expanded and returned through the same gain medium for amplification thereof. The circulating laser beam and returning laser beam pulse travel in different paths through gain medium allowing the use of a small Pockels cell in the oscillator.

Single head laser oscillator-amplifier

A method for laser shock peening a target surface generates laser pulses from a cavity dumping oscillator having an optically-pumped laser and directs the pulses against the target. A first technique uses pulses having rectangular cross section. A second technique passes each generated pulse two or more times through the same optical amplifier before directing the pulse against the target. A third technique drives the laser with a time pulse of electric current having a rectangular shape. A reflective laser beam homogenizer uses two abutting mirrors to split a laser beam into two equal halves and then uses an odd number of additional mirrors to reflect each half first behind and then to the opposite one of the two mirrors to be reflected back as a beam having interchanged halves.

Laser shock peening method and reflective laser beam homogenizer

A method of controlling the size of a laser beam comprises the steps of generating the laser beam with a laser, focusing the laser beam, directing the laser beam to a target, directing a portion of the laser beam to an optical detector which generates a signal representative of a fluence distribution of the laser beam, and adjusting a focal point of the laser beam based on the measured fluence distribution to control the size of the laser beam on the target. The method can be carried out with an apparatus which comprises a beam splitter which divides the laser beam into a first portion and a second portion, a lens which focuses the first portion of the laser beam for incidence on a target, a detector which receives the second portion of the laser beam and which generates a signal representative of a spatial energy distribution of the laser beam, a digitizer which digitizes the signal from the detector, a data analyzer which receives the digitized signal from the digitizer and which calculates a fluence distribution of the laser beam, and a lens controller for adjusting a position of the lens with respect to the target based on the fluence distribution.

Method and apparatus for controlling the size of a laser beam

The invention relates to a method and apparatus for shaping a laser pulse. The method comprises the steps of generating a laser pulse with a laser, opening an optical switch to allow the laser pulse to pass through the optical switch, determining a first reference time point with respect to the laser pulse, determining a second reference time point with respect to the opening of the optical switch, and adjusting an opening time of the optical switch based on the first and second reference time points to shape the laser pulse. The method may be carried out with an apparatus which comprises a laser which generates the laser pulse, a first optical detector which detects the laser pulse and generates a first signal representing the laser pulse, an optical switch through which the laser pulse passes, a second optical detector which detects the laser pulse after the laser pulse has passed through the optical switch, and which generates a second signal representing the laser pulse, a computer which receives the first and second signals and which calculates a delay period based on the first and second signals, and a pulse generator which receives the delay period from the computer and which generates a pulse delayed by the delay period to open the optical switch.

Method and apparatus for shaping a laser pulse

The invention relates to a method and apparatus for accurately measuring the energy of a laser pulse. The method according to one embodiment comprises directing a first laser pulse to an energy sensor which produces a first signal responsive to the first laser pulse, determining a time constant of the energy sensor based on the first signal, directing a second laser pulse to the energy sensor which produces a second signal responsive to the second laser pulse, and determining the pulse energy of the second laser pulse based on the second signal and the time constant. The method may be carried out with an apparatus which comprises an energy sensor which receives a laser beam and generates a signal responsive to the laser beam, a digitizer which digitizes the signal, and a computer which calculates a time constant of the energy detector based on the digitized signal of the first laser pulse incident on the energy detector and calculates an energy of a second laser pulse based on the digitized signal of the second laser pulse and the time constant. The method and apparatus provide accurate and timely energy measurements which can be used to improve the laser shock peening process.

Method and apparatus for measuring laser pulse energy

An oven for heating a crystal for nonlinear frequency conversion of a laser beam. A grasping device resiliently grasps together the first and second sides of the crystal while allowing for generally unrestricted thermal expansion of the crystal. A heater element and a temperature sensor are each supported by the grasping device and are each in thermal contact with the crystal. A temperature controller is connected to the heater element and the temperature sensor.

Oven for heating a crystal for a laser frequency conversion

An exemplary laser apparatus comprises an amplification medium which amplifies a coherent beam passing through the amplification medium, a pump which provides energy to the amplification medium, a tunnel having a first end proximate to the pump and a second end proximate to the amplification medium, wherein the energy provided by the pump passes through the tunnel en route to the amplification medium, and a moveable member for adjusting a spatial distribution of the energy provided to the amplification medium by the pump. The moveable member typically comprises a flat, reflecting strip or flap which redirects a portion of the energy of the pump beam to a peripheral region of the amplification medium. The angular and translational position of the flap is adjustable on line so that the pump distribution can be adjusted while the laser is running to reduce observed optical distortions caused by heating of the amplification medium.

Method and apparatus for adjusting the pump distribution in a laser

A laser head includes a body having opposite ends, and a bore extending axially therethrough for defining a reflector. The body is a unitary member circumferentially around the reflector. The reflector includes a center cavity for coaxially receiving a laser rod, and a plurality of lateral cavities disposed parallel to and extending radially outwardly from the center cavity for receiving flashlamps for optically pumping the laser rod. Reflector and lamp endcaps are removably mounted to the body for mounting the lamps and rod, and allowing individual replacement thereof.

Unitary body laser head

A laser shock peening apparatus includes a cavity dumping laser oscillator including in optical serial alignment a first mirror, a Pockels cell, a polarizer, a laser rod, and a second mirror defining a cavity having an optical length between the mirrors. The laser rod is optically pumped to generate a laser beam in the cavity, and the Pockels cell has selective wave retardation to allow the beam to oscillate between the mirrors and increase energy therein, followed in turn by dumping the beam into a laser amplifier. The laser amplifier directs the amplified pulse at a target for laser shock peening thereof. The cavity length is selected to develop a substantially square-wave laser pulse for temporally shaping the resulting pressure pulse at the target.

Growing community of inventors

Niskayuna, NY, United States of America

Josef Robert Unternahrer