Abstract: In a general aspect, a chirped optical pulse is compressed by operation of diffraction gratings and a dispersive mirror having a smooth reflective surface. In some aspects, a chirped pulse laser system includes a programmable optical dispersive filter (PODF) operable to modify a spectral phase of optical pulses and a pulse compressor that receives an optical pulse based on an output of the PODF. The pulse compressor includes optical elements in a vacuum chamber. The optical elements define an optical path through the pulse compressor, and are arranged to disperse the optical pulse in the optical path. The optical elements include diffraction gratings and a dispersive mirror, which has a smooth reflective surface that defines a portion of the optical path.

Abstract: A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

Abstract: A laser chamber with a circuitous gas return path dissipates shock waves. In one embodiment, the laser chamber includes a heat exchanger with a large surface area that defines an aerodynamic passage through which gas circulates in the laser chamber. The passage through which the gas circulates directs shock waves away from the discharge region so that the shock waves may dissipate elsewhere in the laser chamber. In addition, the large surface area of the heat exchanger efficiently cools the thermally energetic gas within the laser chamber. In another embodiment, ancillary chambers that are fluidically coupled to the main laser chamber are provided to permit shock waves to be directed away from the discharge area and to be dissipated within the ancillary chambers. Openings to the ancillary chambers are positioned such that shock waves generated by the electrode structure of the laser chamber may propagate directly into the ancillary chamber, where the shock waves then dissipate.

Abstract: The COIL gain generator system includes a reactor for producing singlet delta oxygen and a mechanism for mixing high momentum diluent with the singlet delta oxygen and with iodine for producing a high momentum, low static temperature mixture of the singlet delta oxygen, diluent and iodine. The singlet delta oxygen and the iodine react to produce excited iodine atoms which can lase efficiently due to the low static temperature and can, after lasing, recover to high pressure in a diffuser due to the high momentum of the mixture. This provides the capability of using a chemical pump which allows a completely sealed system with no outside exhaust.

Abstract: In an optical path of a laser beam, a reflection mirror (11) is located to divide the laser beam into two split laser beams. By the use of the split laser beams, workpieces (17a, 17b) are simultaneously processed.

Abstract: A laser oscillator includes a housing which seals a laser medium gas from the atmosphere, concave mirrors (or a set of concave and convex mirrors) positioned in the housing and having the laser medium gas therebetween, an apertured mirror positioned between the concave mirror and the other concave or convex mirror on a line connecting the spherical centers of the mirrors at a predetermined angle relative to the line, and a window through which a laser beam reflected by the apertured mirror is output from the housing. The apertured mirror has a curved reflective surface, thereby simplifying the optical system in the housing and increasing the system's reliability.

Abstract: Aerodynamic window for a gas laser, whose active chamber emits a focussed ser beam and is flow connected by means of a beam passage opening with a window chamber connected to a vacuum pump and which has a beam exit opening in an outer area which is preferably under atmospheric pressure. In order to reduce the pumping power necessary for the aerodynamic window and improve the laser beam quality, the window is so constructed that the laser beam emitted by the active chamber has a first focus in the vicinity of the beam passage opening and is deflected onto a focussing mirror arranged in the window chamber and which gives the laser beam leaving the latter a second focus located in the vicinity of the beam exit opening.

Abstract: In a pulsed gas laser apparatus for operation at ambient pressure comprising a laser module having a tubular window open at its distal end for the coupling or uncoupling of a laser beam, the tubular window has a volume which is at least equal to, or a multiple of, the volume change of the laser gas in the module during pulsed laser operation and extends essentially vertically from the laser module. The window includes a mixing zone in which during pulsed laser operation both laser gas and ambient gas are present, the window extending downwardly if the laser gas is lighter than the ambient gas and upwardly if the laser gas is heavier than the ambient gas thereby to counteract infiltration of ambient gas into the window. Also, means are provided for controlling the laser gas volume supplied to the module such that the concentration of the ambient gas in the mixing zone in the window remains below a predetermined limit.

Abstract: An aerodynamic window for gas lasers, has an active chamber with a beam penetration opening free of solids. An end of a beam duct is connected to the beam penetration opening and is transversely penetrated by a nozzle duct of a gas flow window through which compressed gas can flow. A beam outlet opening delivers a laser beam to an exterior space which is preferably at atmospheric pressure. A suction chamber of a differential pump is provided between the other end of the beam duct and the beam outlet opening, and the working pressure of the differential pump is approximately equal to the pressure in the other end of the beam duct on the suction chamber side.

Abstract: In an aero-optical interface for an aircraft optical aperture, the separation of the upstream boundary layer from the edge of the aperture creates a region of turbulance which persists downstream over the full area of the aperture. This invention promotes an early develpment of a steady velocity profile at the upstream aperture edge which is approximately the same as a stable, self-similar shear flow velocity profile over the entire aperture. This is accomplished by thickening the boundary layer upstream of the aperture, and blowing a curtain of air across the aperture from its upstream edge at the point of separation of the boundary flow. This produces a shear flow region foot that causes the overall velocity profile to be equal to a stable self-similar free shear layer.

Abstract: A system for controlling fluid turbulence inside and just outside of a cay adjacent to an opening in a wall, the wall having a forward lip which defines the leading edge of the opening and an aft lip having a leading edge which defines the trailing edge of the opening, the forward lip terminating in a sharp edge lying generally in the plane of the outer surface of the wall. The aft lip has a length of 10 to 50% of the length of the opening and extends into the opening at an angle of 30 to 60 degrees to terminate in an arcuate portion having a radius of 2 to 6% of the length of the opening.

Abstract: A laser beam scanning apparatus, a device for stabilization of the beam intensity distribution, the device comprising an air turbulence generator disposed adjacent a portion of the laser beam optical path and adapted to provide forced air flow substantially thereacross, the forced air flow tending to eliminate variations in the index of refraction of the air layers in the optical path.

Abstract: In order to so improve an aerodynamic window device for a laser which isolates the laser cavity pressure and comprises a jet nozzle and a diffuser arranged opposite the jet nozzle for generating a free jet extending from the jet nozzle to the diffuser and covering an exit aperture, that variable setting of the pressure level in the laser cavity is possible, it is proposed that a side wall (80) of the diffuser (72) which faces away from the laser cavity (34) be adjustable, at least in sections thereof, relative to a free jet direction (68).

Abstract: The aerodynamic window of the present invention provides a barrier between two different environments of a high energy laser device. The first environment is a transverse gas flow across the laser beam and the third environment is an axial flow beam path. The window having a second environment therein changes both the gas temperature and the gas pressure along the laser beam to minimize optical path differences between the first and third environments. The second environment has a thermal transition section and an injection section. In the thermal transition section before the injection section, a gas manifold provides a varying gas flow field. The thermal transition section changes the gas temperature while maintaining its pressure and velocity constant. A transverse flow is exhausted in a location opposite to the gas manifold. The axial flow enters into the injection section. Gas ejectors in the injection section mix the axial flowing gas and increase the gas pressure and velocity.

Abstract: An adaptive gas lens provides a radial flow of gas that makes phase corrections on a distorted annular wavefront passing therethrough. A flexible flange controlled by precision actuators provides for variation in gas stream width yielding variations in the optical path difference over a range of azimuthal periods.

Abstract: An aerodynamic window for a gas laser, comprising a chamber positioned at one end of a structure forming part of a laser cavity in which lasing action can take place the chamber having first and second apertures aligned with the optical axis of the laser cavity and its longitudinal axis at an acute angle to the optical axis of the optical cavity and means whereby the chamber can be continuously evacuated, wherein the chamber is of uniform cross section and the apertures are situated in a side wall and an end wall of the chamber respectively.Preferably, the second aperture is displaced from the longitudinal axis of the chamber towards the first aperture.

Abstract: A boundary-controlled aerodynamic window positioned adjacent the exit aperture of a gas laser is transparent to the laser beam emitted from the cavity of the laser. The boundary-controlled aerodynamic window is formed by a high velocity gas flow directed by a duct across the exit aperture for the laser beam isolating the low pressure region of the cavity from the high pressure of the atmosphere. The exit aperture is enlarged and an auxiliary gas flow injected along the sidewall of the duct adjacent the exit aperture to expand the thickness of the boundary layer. In a second embodiment, particulate matter is fixedly attached to the sidewall of the duct to increase the roughness of the wall surface. A third embodiment uses a plurality of nozzles, each injecting gas with a predetermined velocity.

Abstract: A system for lowering the level of turbulence in an opening through a wall ver which air is flowing at a subsonic velocity wherein an arcuate flange is secured to the downstream edge of the opening and extends into the opening a distance of 0.11 to 0.22 times the length of opening in the direction air flow, the flange being tangent to the wall at the part of attachment of the branch.