Abstract: A method of stabilizing an operation of a continuous axial gas laser including at least one gas flow tube system comprising at least one excitation tube, and a gas flow circulation arrangement connected to the gas flow tube system to generate a gas flow therethrough. The gas flow circulation system generates a timed pulsating gas flow and an output pressure signal having a predetermined frequency spectrum. The flow tube system has a pressure-versus-frequency damping transmission characteristic between an input from the gas flow circulation arrangement and the excitation tube, with the damping varying with a frequency of the pressure pulsations applied to the input. The continuous axial gas laser is stabilized by shifting the predetermined frequency spectrum of the pulsating gas flow generated by the gas circulation arrangement with respect to frequency and the damping transmission characteristic to minimize the pressure pulsations to the excitation tube from the gas flow circulation arrangement.

Abstract: A gas laser device in which a laser medium gas is circulated in an airtight container and a laser beam is generated from the gas excited by an electric discharge, includes a main unit (10) including an air blower (13) for circulating the gas, heat exchangers (12a, 12b) for cooling the gas, and a discharging power supply (11). A laser beam emitter (20) includes a discharging unit (23) and resonator reflecting mirrors (21a, 21b). The main unit (10) and the laser beam emitter (20) are separate and spaced from each other. The main unit (10) and the laser beam emitter (20) are interconnected by a gas pipe assembly having a plurality of highly rigid steel pipes and flexible, expandable/contractable, airtight connector members (31a, 31b) connecting the steel pipes.

Abstract: A laser system having a high power output and a large volume gaseous discharge has a plurality of electrodes at each end of a channel to establish a plurality of discharges and a housing arranged to provide a continuous recirculating lasing gas flow through the channel. An ejector connected to a main circulating pump is fixed to discharge into the recirculating lasing gas flow adjacent the channel to mix lasing gas streams and cause diffusion of the gas and thereby provide a uniform plasma flow in the channel. In one embodiment, magnets are arranged to surround the channel to eliminate thermal instabilities, if they arise, and to further homogenize the lasing gas streams and insure their uniformity.

Abstract: There is disclosed herein several gas resupply valves for replenishment of lost gas in gas lasers in general and argon ion lasers in particular. The first embodiment uses a valve which controls flow of gas into a metering volume. The metering volume has an aperture therein which is microscopically small and which has a diffusion constant for gas moving through the aperture which is less than the time the valve is held open. The second embodiment uses the same general structure, but separates the soft sealing member of the valve from the solenoid core which moves to open and close the valve. The soft sealing member is attached to the valve body and supported above a valve seat surrounding the opening of the metering volume. The third embodiment uses a thin diaphragm which overlies a flat surface of the valve body in which are formed an input port and an output port. A solenoid applies pressure against the diaphragm to cause it to flatten against the flat surface thereby sealing the valve.

Abstract: A CO.sub.2 gas laser device comprises a plurality of divided cathode electrodes disposed in a linear row extending transversely across a high-speed flow of a gas containing CO.sub.2, and parts of the cathode electrodes producing negative glow are disposed at the same height as anodes at a downstream position. Additionally, a device for controlling the distribution of gas flow velocity, which functions doubly as means for creating turbulent flow, and a preliminary discharge electrode are disposed on the upstream side of the cathode electrodes, the former being set at a height position corresponding substantially to that of the middle portions of the cathode electrodes.

Abstract: A honeycomb structure is coated with a catalyst to promote reassociation of CO and O.sub.2 gases to form CO.sub.2. The structure is positioned near the outlet of an optical resonator of a flowing gas CO.sub.2 laser. It is preferably positioned within a gas feedback flow system. Utilization of a honeycomb structure minimizes interference of the gas flow within the laser assembly and reduces the introduction of contaminants.

Abstract: An optical assembly isolator and laser system incorporating the same. The isolator attaches to an end of the laser system along the optical axis of the laser system. The isolator includes a flow loop wall, an optical assembly wall, an outer wall connecting the foregoing two walls, and at least one baffle wall included in the volume defined by the outer wall. The flow loop wall and the baffle wall include open first and second apertures, and the optical assembly wall supports an optical assembly. When the isolator is in place on the laser system, the first and second apertures and the optical assembly all align with the optical axis of the laser system. The edges of the first aperture and the flow loop wall can be slanted and oriented with respect to the primary flow through the laser system to induce a small circulation and redirect any entering shock waves and entrained contaminated gas toward the outer wall.

Abstract: A gas transport laser with longitudinal gas flow and complete integration of the components, having at least one laser tube, wherein the laser gas is drawn off in the center of the respective laser tube, fed through a radial blower, a cooling system and a gas supply system and then supplied to the respective two ends of the laser tube. The laser tube is disposed in general perpendicularly to the direction of the gas flow in the cooling system and the gas supply system extends in the direction of the lesser dimension of the laser system, so as to optimize the use of space. The laser gas is subjected simultaneously to a high frequency and a high voltage discharge to achieve a high degree of efficiency.

Abstract: A co-axial laser tube structure of the kind used in a flowing gas laser has an inner axially extending tube for confining the flowing gas in a discharge region, a single pin cathode mounted adjacent the hot end of the inner tube, a single pin anode mounted intermediate the cool end and the hot end of the inner tube, a gas entrance orifice for permitting gas to flow from the exterior tube into the interior of the tube at the location of the anode electrode means, and an outer tube which is separate from and which extends co-axially with the inner tube. The outer tube is made of plastic and conducts flowing gas along the outside of the inner tube from the cool end to the gas entrance orifice. The co-axial laser tube structure includes tube installation and mounting means effective to permit installation and/or replacement of the inner and outer tubes without the need for subsequent adjustment or bore registration of the tubes.

Abstract: A high-speed axial-flow gas laser generator has a plurality of anodes radially provided at the inlet section of the laser tube, and a ring-shaped cathode is provided on the gas discharge section side of the laser tube. On the upstream side from the anodes, viewed from the laser gas flow in the laser tube, a nozzle is provided which imparts a spiral rotary motion to the gas flow in the laser tube.

Abstract: A fast axial flow gas laser apparatus comprising an at least essentially closed loop defining a flow path for a laser gas, an arrangement for exciting gas flowing in the loop of the apparatus to cause the gas to lase, and a regenerative compressor for flowing gas through the closed loop along the flow path. The compressor is capable of operating with a pressure ratio sufficient to flow the gas along at least a portion of the loop at a speed at least half the speed of sound in the gas with inlet pressures of only a small fraction of an atmosphere. The uniform discharge pressure of the compressor results in a uniform laser discharge or output. A positive pressure fluid pressure seal prevents lubricant at a bearing support for the impeller shaft of the compressor from moving to the impeller and possibly contaminating the laser gas being compressed thereby and also prevents surrounding air from contaminating the laser gas.

Abstract: There is disclosed herein several gas resupply valves for replenishment of lost gas in gas lasers in general and argon ion lasers in particular. The first embodiment uses a valve which controls flow of gas into a metering volume. The metering volume has an aperture therein which is microscopically small and which has a diffusion constant for gas moving through the aperture which is less than the time the valve is held open. The second embodiment uses the same general structure, but separates the soft sealing member of the valve from the solenoid core which moves to open and close the valve. The soft sealing member is attached to the valve body and supported above a valve seat surrounding the opening of the metering volume. The third embodiment uses a thin diaphragm which overlies a flat surface of the valve body in which are formed an input port and an output port. A solenoid applies pressure against the diaphragm to cause it to flatten against the flat surface thereby sealing the valve.

Abstract: A device for the preparation of a gas mixture includes a closed circuit. Mixture components of a gas mixture are fed with greatly differing partial pressures ranging from low to highest partial pressures to the closed circuit. The gas mixture is circulated in the closed circuit. At least one of the mixture components with low partial pressure is replenished at increasingly shorter intervals. The gas mixture is completely exchanged when a given minimal length of the intervals is reached. At least one branch parallel to a section of the closed circuit conducts the gas mixture substantially completely free of flow losses.

Abstract: A high frequency discharge excited coaxial type CO.sub.2 laser is provided, which has both the advantageous characteristic of high frequency excitation type, namely, small size and high efficiency, and the advantageous characteristic of coaxial type, namely, high quality beam mode. This laser includes a dielectric laser tube and two helical electric conductors of the same pitch, and a high frequency voltage is applied between the conductors by a high frequency power source while the CO.sub.2 laser gas is passed axially in the laser tube.

Abstract: A laser resonator system including an optical resonator whose side wall has an orifice through which gas may enter the resonator's interior, and may subsequently flow along the resonator's longitudinal axis. An elongated electrode (which preferably is an anode) is positioned at the orifice in electrical communication with the entering gas so that the projection of the electrode's tip on the plane of the orifice does not coincide with the center of the orifice. In a preferred embodiment, the electrode's longitudinal axis is aligned generally perpendicular to the plane of the orifice. In another preferred embodiment, two such electrode-orifice pairs are provided and are separated by a small distance along the resonator's axis. The orifice positions are preferably on opposite sides of the resonator, so that they are separated by an azimuthal angle substantially equal to 180.degree. with respect to the resonator tube's longitudinal axis.

Abstract: A laser fluid control apparatus and method provide selective, precise control of the fluid supplied to the laser. The flow of the fluid to the laser can be automatically adjusted according to a selected, programmed control to provide a high volume of the fluid to the laser during initial operation of the laser for a quick warm-up of the laser and a reduced volume after the laser has warmed-up for more economical operation of the laser. Different fluid mixes can also be provided for enhancing laser performance. A control for pulsed or continuous wave laser operation can be actuated to automatically change the composition of the fluid supplied to the laser for continuous wave laser operation as compared to that for pulsed operation.

Abstract: A metal vapor laser which can produce two or more discrete outputs from a single vacuum chamber. This is achieved by using two or more different materials and by confining each material to its own area so that the materials do not mix one with the other and optimum lasing performance can be obtained from each material. All the lasing areas have a common optical axis. The lasing outputs can be produced separately or mixed together as required.

Abstract: A gas laser generator comprises a frame, a gas channel through which a gas flows, a mirror for obtaining a laser beam, defining a resonant cavity, an anode electrode and at least two first and at least two second cathode electrodes arranged in the lower and the upper portions of the resonant cavity, respectively, and a power source, in which a first voltage of a first electric field between the first cathode electrodes connected to the power source through a first ballast resistance and the anode electrode and a second voltage of a second electric field between the second cathode electrodes connected to the power source through a second ballast resistance and the anode electrode are so determined that the former is smaller than the latter so that the current flowing in the first electric field may be substantially equal to the current flowing in the second electric field during the electric discharges between the electrodes.

Abstract: A chemical iodine laser system 10 is provided with a reactive iodine producing container (12) for housing a reactive iodine generating composition. Singlet delta oxygen produced by oxygen generator (30) is mixed with iodine atoms and conveyed to a laser cavity.

Abstract: The premixed cold reaction CW chemical laser places the secondary injectors which input fuel and/or diluent in the exit walls of the primary nozzle. These injectors are acutely angled thereto and are arranged in rows and are further grouped therein where a first injector inputs a pure diluent, a second group of injectors inputs independently of a third group.

Abstract: A gas laser device comprises a discharge tube made of a dielectric material; a laser medium gas which is circulated at a high speed within the discharge tube in the axial direction of the discharge tube; an optical resonator composed of a total refelection mirror and a partial reflection mirror, both being disposed in mutual confrontation at both ends of the discharge tube; a plurality of electrodes oppositely provided on the outer periphery of the discharge tube; and a power source for applying an a.c. voltage to the oppositely provided electrodes to generate silent discharge.

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: A gas laser oscillator having a gas flow smoothing device, preferably made of a cylindrical mesh, installed in the gas inlet of the electrical discharge region of the oscillator.

Abstract: A metal vapor laser which has an optical cavity, and a sputtering cell arranged at one end. The sputtering cell has a sputtering surface for sputtering metal deposited on the surface or from which the surface is formed. A gas stream is introduced into the cavity for entraining the sputtered metal into a metal vapor beam and the gas stream is introduced such that the gas stream flows substantially parallel to at least a part of the sputtering surface to ensure that the passage for introducing the gas is aligned correctly relative to the sputtering surface, there is provided an insulative ring formed in two portions defining the passage therebetween and the first portion of the ring is moveable with respect to the second portion thereof to align a passage. Two sources of gas are provided for forming the gas stream and are selectively switched so that each source of gas can be selectively coupled to the cavity for forming a gas stream of a particular variety of gas.

Abstract: A chemically driven HF overtone laser operates from either thermal or electrical dissociation of a molecular gas containing fluorine. Significant output powers are produced from .DELTA.v=2 vibrational transitions. Free F atoms produced by both thermal and electrical dissociation techniques are reacted with a molecular gas containing hydrogen to produce excited HF molecules. Overtone transitions, i.e., .DELTA.v=2 transitions are preferentially depleted by both optical enhancement and preinjection techniques to produce overtone laser transitions.

Abstract: A laser discharge tube is provide having a ceramic rod of rectangular cross section through which extends a discharge channel and at least one gas return channel, and cooling plates affixed at the larger outside surfaces of the rectangular ceramic rod.

Abstract: A high frequency cross-flow gas laser has a tubular conduit divided into a multiplicity of gas flow sections with gas inlets adjacent each of the mirrors therein and outlets therebetween. A pair of electrodes is provided along each flow section to produce a high frequency electrical discharge in the lasing gas mixture, and a cooler is used to chill the gas withdrawn from the conduit for recycling thereto. The electrode pairs are desirably radially rotated relative to one another to produce uniformity of the energy discharge across the cross-section of the lasing gas mixture.

Abstract: For the excitation of a discharge in a laser gas, an electrode arrangement is provided which consists of at least two elongated electrodes wound approximately in a cylindrical helical line. The double helix thus formed is arranged on or concentrically within a gas flow tube.

Abstract: A piezoelectric fan is comprised of two counter-oscillating flexible blades that are driven at resonance by a bimorph comprised of two piezoceramic bending elements. The fan is provided within the flow duct of a circulating gas laser. The operation of the piezoelectric fan serves to create a flow of a laser gas medium in a desired direction through the flow duct, thereby replenishing the gas medium between a pair of laser electrodes. The fan has no wearing elements, such as bearings, and requires no bearing lubricant resulting in the elimination of lubricant hydrocarbon and bearing particulate contamination of the laser gas medium.

Abstract: In a gas laser device according to this invention, a gas inlet having an electrode protrudes within each of expanded portions protruding on the side, where the gas inlet is disposed, of the principal portion of the discharge tube. Gas medium ejected from the gas inlet in the principal portion of a discharge tube collides with the inner surface of the principal portion of a discharge tube, while forming a flame extending along the ejected gas medium from the electrode and is divided into two partial flows. One of them flows along the wall of the expanded portion; collides with the gas inlet; and is divided further into two partial flows. Therefore it does not collide with the gas medium within the gas inlet. Consequently the gas medium and the flame fluctuate hardly and are stabilized. In this way it is possible to stabilize the laser output.

Abstract: A laser tube for a laser generator used in a laser machining tool is formed by a plurality of disks laminated together to form an integral unit. The disks have a main hole for the passage of laser gas and at least one sub-hole for a sub-flow of laser gas. The sub-hole of each disk is connected with the respective main hole of the disk by a gas injection channel through which laser gas is injected into the main hole at a plurality of longitudinal positions in the laser tube to provide a homogeneous laser gas velocity distribution in the laser tube.

Abstract: The subject invention relates to a conduction cooled ion laser capable of producing higher output power. The device includes an insulated tube and a plurality of heat conducting members mounted in thermal contact with the wall of the tube. Primary and secondary ring gas barriers or shields project axially from the heat conducting members with the primary shield being located radially inward with respect to the secondary shield. The shields are mounted such that they axially overlap to define a reentrant configuration. The reentrant configuration allows for the operation of the laser at a higher power with the same voltage safety margin above the instability voltage.

Abstract: A laser oscillating apparatus has a compact, simple structure by utilizing the laser housing itself as an optical bench. Means for thermal expansion and contraction in the longitudinal direction of the laser housing are supported in the laser housing as a united body. The blower which circulates the lasing gases is constructed of a plurality of fans mounted for separate thermal expansion and contraction, enabling the use of high speed fans. Means are provided between the blower and the lasing region for cooling and smoothing the gas flow. The cap of the laser apparatus is arranged at the strength center of the housing to ensure a gas-tight interior.

Abstract: A laser oscillating apparatus includes a laser housing, means for generating a prescribed gas flow within the housing, a discharge electrodes assembly for carrying out predetermined discharge within the gas flow, and an optical oscillating apparatus for resonating the ray of radiation generated in the discharge. The discharge electrodes assembly includes an insulated substrate, a plurality of pin-shaped electrodes planted on the substrate a ballast capacitor arranged on the rear side of the substrate and connected to the pin-shaped electrodes end and a cooling tube arranged adjacent to the capacitor and the insulated substrate. At least the ballast capacitor and the cooling tube are molded on the rear side of the substrate.

Abstract: In a gas laser including a discharge tube forming a resonant cavity, a mirror disposed at each end of the cavity, a pump, a gas source and a manometer, a first valve is connected between one end of the tube and a first of the mirrors and a second valve is connected between the other end of the tube and a second of the mirrors. Within the body of each valve is a moving element which may assume a first working position, a second position permitting mirror access and a third position for changing gas. This arrangement permits changing mirrors and/or replacing gas without exposing the cavity to atmospheric pressure and without loss of time.

Abstract: The present invention provides a Ram airbreathing laser adapted to use with an aircraft which operates primarily in the Mach 3 to Mach 6 regime. Valves, or gates, are provided in the propulsive flow path and the auxiliary flow path for laser in a manner such that the air entering the aircraft engine inlet duct system is either directed to the laser or to the propulsive flow path depending upon the desired mode of operation of the aircraft.

Abstract: A gas laser is provided with elongated electrodes having apertures therein. he electrodes provide a transmission line for an HF electromagnetic pump which ionizes the gas, and the apertures are distributed and offset to provide passageways for efficient interaction between the hot ionized gas and a replenishing supply of cooled gas.

Abstract: A fast axial flow folded laser includes a vessel which houses heat exchangers and a pump which imparts the pumping action throughout the laser. Only one housing is necessary and this housing can also be used as an optical bench for the resonator. In one embodiment a positive displacement rotary pump is utilized and a retroreflector included to mount three fold mirrors. In the folded configuration the retroreflector provides angular stability in any two orthogonal planes parallel to the laser beam.

Abstract: The generator comprises an optical cavity (3, 4) resonating according to an axis (2) and two annular electrodes (5, 6) disposed along said axis, one of said electrodes (5) being provided with gas injection channels (9, 10) having injection axes (11, 12) directed toward the other electrode (6) and inclined at an angle of 45.degree. with respect to the axis (2) of the resonator, the number and the cross-section of said channels (9, 10 . . . ) being selected to enable the laser gas to be injected at supersonic speed. The operating method consists in maintaining a laser gas pressure upstream from the injection channels (9, 10) which is at least 50% greater than the downstream pressure.

Abstract: An axial flow gas transport laser comprising an excitation tube through which gas flows along an axis of the tube, an inlet arrangement to feed gas towards the excitation tube and an outlet arrangement to discharge gas from the excitation tube. At least one of the inlet and outlet arrangements comprises a circumferential opening arrangement evenly distributed along the periphery of the excitation tube, substantially in a cross-section plane of the tube. A gas flow channel arrangement to the opening arrangement is directed at least substantially in the direction of the excitation tube axis and into the excitation tube at the opening arrangement for preventing wide-areal turbulances of the gas flowing in the excitation tube.

Abstract: A laser having a deflector in which bypass gas is separated from a cathode and the local discharge region around the cathode, and in which the bypass gas has a relatively long open passage around the deflector to the cathode. The deflector has an open end surrounding at least a portion of the cathode and an aperture and having an aperture and a raised shoulder connected to the end of a laser tube. The aperture is aligned with the discharge bore of the laser tube with gas bypass bores outside of the aperture enclosed by the shoulder. The anode end of the laser tube may also have a deflector which is an annular washer having an aperture and a raised shoulder. The washer has a diameter nearly as large as the anode in which it is mounted.

Abstract: To improve the power transfer of a glow discharge between a cathode (3) and an anode (4) in a glow discharge space (2), through which a laser-active is being passed (5) at high speed, the cathode is constructed to have a rotating surface, projecting through slits (8) of the walls (1) defining the discharge space into the discharge space, the tangential or surface speed of the cathode (3) being at least approximately equal to the flow speed of the gas, so that the gas will flow along the cathode in essentially laminar, linear flow, thereby avoiding turbulence at the surface and instabilities in the glow discharge.

Abstract: A gas laser of the type in which gas is impelled transversely through a region where lasing of the flowing gas occurs, employs a crossfield blower to propel the gas around a closed loop. The crossfield blower has an elongate impeller that is substantially the same length as the lasing region. The impeller generates at least one vortex in the gas flow. A part of that vortex is situated outside the path of the main gas flow to the lasing region. To remove heat from the gas without appreciably interfering with the main gas flow to the lasing region, cooling means are situated in that part of the vortex that is outside the path of the main gas flow to the lasing region.

Abstract: A plasma tube for a gas laser includes a series of heat webs and insulative spacers between the heat webs, with tungsten bore insert members supported by the heat webs and having aligned apertures defining a laser discharge path. To produce the plasma tube, the heat webs, spacers and other connected components are assembled in a vertical stack outside the ceramic tube of the laser, with a stacking gauge which helps assure that the heat webs are correctly spaced apart within close tolerances. The heat webs lie adjacent to annular metallized areas on the inside surface of the ceramic tube when the assembly is inserted into the tube, which is precision-formed ceramic tubing. The tube assembly is heated in vertical orientation to expand the heat webs diametrically so that they engage outwardly against and are brazed to the metallized areas of the ceramic tube.

Abstract: A fast axial flow carbon dioxide laser has a laser head arranged to provide multiple folding of the laser beam into two, four or more linear passes. The construction of the head is such as to provide for generating either one laser beam or a pair of beams, by adjustment of optics. Located centrally in the laser head is a single exhaust manifold for exhausting all of the axially flowing gas from a series of colinear and spaced parallel discharge tubes on opposite sides of the exhaust manifold. Gas flow is from two outer inlet manifolds toward the central exhaust manifold, so that optics of the system are isolated from contamination and from the hot exhaust. Adequate distribution of gas within each discharge tube is assured by the manner in which the flowing gas is directed into the discharge tubes.

Abstract: In a gas transport laser with axial gas flow, a radial blower is provided for the gas circulation on the axis of which a laser resonator has been arranged. The laser resonator is concentrically enclosed by a ring channel serving as a cooling section. For this purpose, several heat exchangers are provided in the ring channel which are connected to a water reservoir. The water reservoir preferably serves as the cover plate of the radial turbine, and carries--at the same time--the cathode being shaped as a ring electrode.

Abstract: In a laser resonator having a gas-introducing portion at one end of a laser tube, where the gas introducing portion comprises an inner tube communicating with the laser tube and an outer tube covering the inner tube. The inner tube has a plurality of circumferentially spaced apart flow passages so that a gas mixture fed from a gas source to an annular chamber defined between the inner surface of the outer tube and the outer surface of the inner tube, is led into the inside of the inner tube via the flow passages. As a result, turbulence occurs within the inner tube so that radial distribution of gas flow speed in the laser tube is made uniform, thereby increasing the maximum output and stability. The flow passages may be slits, oval or circular openings, triangular openings or the like.

Abstract: A high-speed axial flow gas laser oscillator has plurality of laser tubes arranged parallel to and interconnected with one another to form a plurality of parallel, straight length sections for resonating and amplifying a laser gas, electrode means associated with the laser tubes for ionizing and thereby incidently heating a laser gas circulated therethrough, means for circulating the laser gas through the laser oscillator, and heat exchanger means for cooling the laser gas circulated through the laser oscillator. A plurality of gas recirculation paths are positioned on opposite sides of the laser gas circulating means and are disposed symmetrically with respect to the laser gas circulating means and the parallel, straight length sections formed by the laser tubes.

Abstract: A pulsed electrical discharge gas laser uses acoustic diodes to cause the gas to circulate between the active region of the laser and a gas heat exchanger. The diodes take the form of asymmetrical obstacles placed within the gas flow exhibit asymmetrical resistance to the passage of compression waves in the gas that are generated by the electrical discharge and, as a consequence, cause a net flow of gas in one direction through the obstacles, thus causing the gas to circulate from the active region of the laser through the gas heat exchanger and return. A series of columns having cup-shaped cross sections act as the acoustic diodes.

Abstract: An optical path length changing arrangement employing a selected cross-section of pressurized gases or other fluid and usable in a space weapon chemical laser and in other optical equipment for phase changes along a transmitted wavefront. Use of a heavy, high-refraction index gas such as Freon.RTM. or nitrogen as the optical path length correcting medium is disclosed, along with adjacent buffering streams of a light, low optical refraction gas such as helium.