Abstract: A waveguide laser having a gain medium excited by a capacitively coupled self-sustained discharge is disclosed. The gain medium is disposed within a dielectric waveguide having a capillary bore centrally located therein. A gain medium such as a rare gas halide mixture is excited by a capacitively coupled discharge between a power electrode circumferentially and axially enveloping a central portion of the waveguide and ground electrodes disposed proximate the ends of the waveguide between the mirrors defining the optical cavity of the laser. A preferred embodiment of the laser further includes means for circulating the gain medium through the waveguide. The present invention is adapted for providing pulses of radiation having a wavelength in the ultraviolet and visible spectrum and pulse widths typically less than 30 nanoseconds with peak powers in excess of one kilowatt.

Abstract: An apparatus adapted for rotating a beam of radiation to obtain azimuthal and radial time averaging of the intensity distribution incident onto a workpiece is disclosed. The apparatus includes a housing adapted for rotation about a centerline axis, an entrance port and an exit port adapted for transmitting a beam of radiation through the housing, an inverter disposed within an internal passage within the housing and fixedly attached to the housing for rotation therewith includes a first mirror having a reflective surface angularly disposed to the rotation axis adapted for reflecting radiation incident thereon to a second mirror, a second mirror having a reflective surface adapted for reflecting radiation incident thereon to a third mirror having a reflective surface angularly disposed to the rotation axis adapted for passing radiation incident thereon through the exit port.

Abstract: In accordance with the present invention, output beams from a plurality of optical amplifiers in an oscillator-amplifier optical configuration are phase matched utilizing a feedback system employing phase error signals generated by optically heterodyning a frequency shifted, two-wavelength reference beam, with a portion of the output from each of the plurality of amplifiers. Electrical signals from detectors responsive to the optical heterodyned signals are processed in control circuits to provide coarse and fine phase error signals to control elements for controlling the optical path difference of the beams of radiation passing through each of the amplifiers for phase matching the beams.

Abstract: A method of mitigating 2.pi.N phase ambiguity in an adaptive optics control system is disclosed wherein the radiation sensed by a detector within a feedback loop is passed through an aperture having a variable diameter. The turn-on of the adaptive optics control system is initiated with the aperture in an open position to transmit radiation from all actuator zones onto the detector resulting in a convergence free of the 2.pi.N phase ambiguity. The diameter of the aperture is then reduced slowly compared to the bandwidth of the control system to converge to a near diffraction limited output beam at the aperture.

Abstract: A mechanical scanning apparatus adapted for oscillating the focus zone of a beam of radiation having high power to modify and control the nature and extent of the interaction zone on a workpiece is disclosed. The apparatus includes a compound beam adapted for being vibrated in a vibratory mode resulting in oscillatory motion of at least a first end of the compound beam; a reflective surface attached to the first end of the compound beam and adapted for focussing radiation incident thereon to a focus zone, and means for vibrating the compound beam to induce oscillatory motion of the reflective surface resulting in oscillatory motion of the focus zone. For vibration frequencies greater than the characteristic thermal response time of the workpiece material, the effect is a broadening of the interaction zone with a beam-material interaction characteristic of a reduced incident average power intensity while maintaining a high local intensity essential to the establishment of effective radiation-material coupling.

Abstract: An improved electrode configuration and method for the deposition of electrical power into an electric discharge laser having a gas path transversely disposed to an optical axis and the electric field is disclosed. The electrode configuration includes a cathode, having one or more common geometry rod elements of a thoriated material disposed transverse to a gas path and a planar anode disposed opposite the cathode in a parallel relationship thereto wherein the cathode and the anode define the gas path therebetween. The electrode configuration is adapted for operation without ballast resistance in the electrical circuit and without the utilization of preionization means. The electrode configuration provides a discharge having substantially diffuse and uniform characteristics within the discharge region.

Abstract: An apparatus for monitoring the optical quality of a beam of coherent radiation or of an image from an incoherent source is disclosed. The apparatus includes a disk capable of being rotated, a plurality of slit sets circumferentially disposed about the disk at a radial position where each slit set includes a first and second slit disposed in an orthogonal relationship to one another and symmetrically disposed about a radius line extending from the radial position of the slit sets to the center of the disk and a third slit disposed symmetrically between the first and second slits. The slit sets are adapted for scanning a focused beam of radiation in the zero, forty-five and ninety degree direction to provide data pulses proportional to beam jitter and astigmatism. Variable positioning of successive slit sets within the axial dimension of the disk provides pulses having configurations proportional to the defocus of the focused beam.

Abstract: A mirror adapted for compensating thermal distortions resulting from the absorption of energy in a beam of radiation incident thereon is disclosed. Coolant channels disposed within the mirror proximate the reflective surface are adapted for passing coolant therethrough to minimize the temperature rise in the mirror resulting from the absorbed energy and the resulting thermal distortions therein. Heating channels disposed within the mirror proximate the back surface are adapted for passing a heating fluid therethrough for increasing the temperature of the back surface to induce thermal distortions therein, said induced thermal distortions having a direction and magnitude to counter the distortions resulting from the absorption of radiant energy at the reflective surface of the mirror.

Abstract: A resonator feedback system is disclosed wherein the output from a resonator having adaptive optics is monitored by a detector within a feedback loop to provide electrical control signals to actuators attached to the adaptive optics to control the phase of the radiation within the resonator to produce an output beam having a near diffraction limited distribution. In one embodiment, a portion of the output beam is phase modulated at discrete frequencies and focused through an aperture onto a detector. Far field amplitude fluctuations at the focal point resulting from phase perturbations of the radiation within the resonator produces an amplitude varying electrical input signal which is synchronously detected with multidither signals utilized to impress the phase modulation to produce multicorrection signals.

Abstract: An improved apparatus for monitoring the optical quality of a beam of coherent radiation or an image from an incoherent source is disclosed. The apparatus includes a disk capable of being rotated and having a plurality of rings of slit sets radially disposed within the disk symmetrically about a central axis at a plurality of radial positions wherein each ring of slit sets includes a plurality of slit sets, symmetrically disposed about the ring, each adapted for passing a focused beam of radiation therethrough. A suitable beam steering mechanism such as an adjustable mirror is adapted for directing focused radiation from a first ring to a second ring for varying the intensity of the radiation passing through the slits to detector means for improved signal processing and for varying the parameters of the slits passing the radiation for optimizing the measurement of various beam parameters for determining the optical quality of the radiation.

Abstract: An improved nozzle array adapted for use in chemical lasers is disclosed. The sidewalls of the nozzle array include a restoring bar fixedly attached thereto adapted for elastically restoring plastic thermal deformation of the array. The nozzle array includes a plurality of nozzle manifolds disposed along the length of the array with relief slots disposed between each of the nozzle manifolds. Rigid support walls of the laser housing constrain thermal deformation of the array in the lengthwise direction while the array is adapted for unrestrained thermal expansion in the spanwise direction thereby minimizing corner shear strains resulting from thermal deformation during the operation of the laser.

Abstract: An improved electro-optic moduator device is disclosed which provides strain-free mounting of an electro-optic crystal within a housing assembly and suppression of acousto-optic effects within the crystal. An acoustic matching liquid having an acoustic impedance substantially matching the acoustic impedance of the electro-optic crystal is disposed within the housing enveloping longitudinally the crystal. The acoustic matching liquid effectively suppresses the acousto-optic resonances within the crystal by coupling the acoustic energy out of the crystal into the liquid. The liquid enveloping the crystal also provides a uniform heat conduction path for minimizing thermal gradient variations and the resulting thermally induced strain within the crystal. A zinc oxide suspension in silicone oil is an exemplary acoustic matching liquid for gallium arsenide or cadmium telluride crystals.

Abstract: An automated welding facility for the fabrication of shell sections suitable for ship construction utilizing laser welding is disclosed. The facility includes a panel welding station which includes an optical system for providing radiation for automated two-sided welding of plates to form panels utilizing sequential welding of the top and bottom halves of the plates. The panel welding station is adapted for aligning the plates to form a seam therebetween and for providing tack welds along the length of abutting plates while simultaneously providing position coordinates of the seam to a controller adapted for controlling the positioning of laser welding heads for automating finish welding of the plates to form panels. The panel welding station further includes automated means for marking the panels for positioning stiffeners, webs and/or bulkheads thereon.

Abstract: An apparatus for welding T-frame stiffeners circumferentially to the interior surface of a cylindrical shell at selected axial positions to fabricate reinforced hull sections suitable for boat construction is disclosed. The apparatus is adapted for providing simultaneous two-sided Tee welds of the T-frame to the shell using radiation from a laser source to form quickly the welds which significantly reduces the time and costs of fabricating hull subassemblies.