Abstract: A system for temporal pulse shaping of laser radiation beams particularly for use as photoexcitation radiation in isotope separation. Each pulse of laser radiation is temporally segmented into two or more sections. The sections may be superimposed after a delay in the leading one to augment the pulse intensity, or the segmented pulses may be separately used as segments in a desired application, or the pulse rise time may be decreased by segmenting the pulse so as to permit rejection of the more slowly rising leading edge.

Abstract: A mirror for reflecting the high power radiation of laser beams while maintaining the predetermined shape of the reflecting surface. Radiation is reflected by a front, typically dielectric, surface on a transparent substrate. Since some power is unavoidably absorbed at the reflecting surface, the mirror will experience a thermal expansion. Some incident radiation is also transmitted to the opposite side of the substrate where at least a portion of the transmitted radiation is absorbed to a degree preselected to provide thermal expansion of that opposite side complementary to the expansion of the reflecting surface. The two expansions can be adjusted such that the shape of the reflecting surface is affected far less by the incident radiation than in the case where no opposite side absorption is provided.

Abstract: The ion separation electrodes in isotope separation apparatus are provided with removable collection shields to collect neutral particles which would normally pass through the ionization region. A preferred collection shield comprises a U-shaped section for clipping onto the leading edge of an electrode and a pair of flanges projecting substantially perpendicular to the clipping section for collecting neutral particles.

Abstract: An optical commutation system for commutating pulsed radiation between a common path of relatively high pulse rate and plural, closed spaced, slowly diverging paths on which the pulses are distributed. The system may thus act as a combiner or decombiner. The system employs a reflective or refractive optical element which is driven to produce a very slight oscillation in the orientation of the refractive or reflective surface of the element typically ranging over only a few degrees. The angle of oscillation is kept as small as possible, being only large enough to resolve or separate the radiation pulses on the slowly diverging paths. The very slight angular variation between adjacent ones of the diverging paths permits a large number of beams to be packed together in the bundle of diverging paths, but because of the slight angular variation, only a small angular scan resulting from the finite pulse duration is experienced. This can be kept well within acceptable limits for use with long path lengths.

Abstract: A CO.sub.2 medium is optically pumped by a five micron CO laser to the 03'0 level which radiates with 16 micron emission to the 02.degree.0 level. The resulting 16 micron laser finds application in laser uranium enrichment operating to provide excitation of uranium hexafluoride particles. Terminal level blockage, or bottlenecking, in the 02.degree.0 level is optionally avoided for continuous mode operation by 10 micron excitation with a CO.sub.2 laser from the 02.degree.0 to the 00.degree.1 level. The CO.sub.2 is then diluted by mixing nitrogen gas with it to promote energy transfer to the V=1 vibrational level of the nitrogen, thereby insuring maintenance of the inversion necessary for efficient, high power lasing in the 03'0 to 02.degree.0 transition.

Abstract: A system of wholly passive or static elements for increasing laser pulse rate by interleaving the pulses of a plurality of beams of pulsed laser radiation. The system of static elements includes an array of beam splitters which are operative to receive a plurality of beams of pulsed laser radiation and provide a plurality of output beams, each sharing the radiation in each of the input beams. The invention includes a methodology for expanding the array of beam splitter elements to combine any number of input beams, of whatever differing characteristics, to provide a corresponding number of output beams, each sharing a portion of the radiation in each of the input beams.

Abstract: In an injection-locked laser system, a timing system for assuring the locking of an injection-locked oscillator to the frequency of a master oscillator. The system automatically controls the firing of the injection-locked oscillator in accordance with the difference in time between the production of a master oscillator pulse and the time that a predetermined population inversion level has been reached in the injection-locked oscillator as measured by a predetermined level of fluorescence produced by the injection-locked oscillator.

Abstract: Method and apparatus for sputtering particles of plural isotope types to produce a particle flow of the plural isotope types into a region where laser radiation is generated to produce isotopically selective ionization of at least one isotope type in the sputtered particle flow. Separate collection of the ionized particles is accomplished through application of a magnetic field in the region of ionization and beyond.

Abstract: Apparatus and method for supplying feedstock to a reservoir containing material having a portion which is heated to a molten condition and vaporized by an electron beam. The electron beam is supplied from a heated filament and directed to impact on the vapor source material by electric and magnetic fields. The feedstock is suspended above a portion of the reservoir out of the path of the electron beam. Skip electrons along with some secondary electrons emitted from the surface of the material in the vicinity of the region of electron beam impact, together with radiant heating therefrom, are utilized to melt an exposed portion of the feedstock, allowing it to drip into the reservoir, and replenish the supply of material which is depleted by vaporization. Vaporization is maintained substantially uniform from the region of electron beam impact and splatter of the feedstock is largely avoided.

Abstract: A system for making optimum use of frequency shifted radiation by extracting both front and back travelling frequency shifted radiation beams. The two extracted laser beams are later combined in the same polarization for energization of a dye laser channel or cell for increased pumping efficiency in the dye laser operation. Additionally, where the generating cavity for the two beams is mode locked, the two extracted beams may be applied to the dye laser cell in time staggered manner in order to maintain the stability of subsequent amplification stages between pulses.

Abstract: A system for temporal pulse shaping of laser radiation beams particularly for use as photoexcitation radiation in isotope separation. Each pulse of laser radiation is temporally segmented into two or more sections. The sections are superimposed after a delay in the leading one to augment the pulse intensity.

Abstract: Method and apparatus for achieving isotopically selective adiabatic inversion, particularly for improved isotope separation efficiency. In a preferred embodiment for practicing the invention, chirped laser radiation induces photoionization of a vapor state material in isotopically selective excitation and ionization energy steps. A frequency sweep or "chirp" is provided in the excitation laser radiation at a controlled rate and over a range of frequencies which is limited to prevent loss of selectivity in the excitation. The frequency swept radiation has a theoretical capability of producing 100% inversion of ground state particles in the vapor. The features of the invention additionally permit excitation of a material to very high energy states useful in producing high frequency, ultraviolet lasing.

Abstract: A system for providing multiple traversal illumination of a region with a beam of radiation wherein the illumination provides substantial but not complete overlap at each repeated pass of the beam throughout the region. Because there is a slight shift in direction of the beam on each traversal of the region, it is possible to apply the beam and extract it after a predetermined number of traversals, and means are provided for this purpose. In addition, more than one beam may be applied to the same region, each having a different, predetermined number of traversals before extraction. In this manner, a form of beam combination is achieved.

Abstract: A CO.sub.2 laser capable of emitting at 16 microns in the transition from the 02.degree.O to the 01'0 energy levels. The laser is particularly adaptable for use in laser enrichment to photoexcite uranium hexafluoride molecules. The CO.sub.2 medium is originally excited to many levels above and including the 02.degree.0 level. De-excitation to the 02.degree.0 level is induced from several upper levels populating it highly for improved laser gain. The transition between the 02.degree.0 and 01'0 levels at 16 microns is then permitted by depopulating the 01'0 level with 5 micron radiation from a CO laser. In the preferred case, excitation of the CO.sub.2 medium is by an electronic discharge, and all levels are excited from the ground state by the discharge without selectivity. The pumping from the terminal 01'0 level maintains the inversion for 16 microns lasing.

Abstract: A system for correcting misalignment and divergence in a long, propagating beam of radiation as is typically applied through a plurality of chambers to produce isotopically selective photoexcitation in a system for isotope separation. The corrective apparatus comprises a reflective relay system placed at predetermined intervals along the path of propagation of the radiation where correction of alignment and/or divergence are required. The reflective relay includes a concave mirror employed to correct divergence and which receives radiation directed at it by a first plane reflective surface which in turn responds to the radiation on the path of propagation. The concave mirror reflects toward a second plane mirror which in turn reflects the radiation back onto the path of beam propagation with correction of alignment and divergence.

Abstract: Method and apparatus for isotope separation by selective ionization of a desired isotope in an environment of plural isotopes without corresponding ionization of the other isotopes in the environment. The selective ionization is achieved through a three step excitation of atoms of the desired isotope in response to laser radiations applied to the environment. The transition for each step is selected to be less than one half the ionization potential for the isotopes to avoid two step nonselective ionization.

Abstract: Apparatus to reduce pyrophoricity in deposits collected upon collection plates within a chamber employed for vapor deposition. The apparatus is preferably employed in a chamber utilized for isotopically selective photoexcitation, ionization and separation of metallic uranium vapor. The uranium vapor which collects on all surfaces exposed to it within the chamber is caused to collect in a relatively dense, non-porous body by maintaining a suitably elevated temperature for those surfaces while at the same time keeping the chamber itself cooled. The elevated temperature is achieved by baffles shielding the collection plates from the cooler chamber walls to reduce thermal radiation thereto and/or by applying additional thermal energy to the plates.

Abstract: A system for multiplexing or demultiplexing pulsed laser radiation having an acousto-optical device which is electrically controlled to switch a common path of high pulse rate laser radiation between a plurality of spatially distinct paths for relatively lower pulse rate laser radiation at which the pulses are sequenced according to a predetermined time pattern. The acousto-optical element typically includes a Bragg cell which is electrically driven by a set of distinct frequencies, causing deflection of radiation passing therethrough at a predetermined set of angles whereby pulsed radiation on a single path may be distributed onto the plural separate paths or radiation on plural separate paths of time-sequenced pulses of radiation can be combined into a single path of augmented pulse rate.

Abstract: A ring laser configuration operative to reduce divergence in the laser beam circulating within the ring and provided as an output. The ring laser configuration includes an odd number of reflectors in the ring path with one or more polarizer crystals for providing input and output coupling. The use of an odd number of reflectors creates an inversion in each pass of the radiation through a flowing active medium within the ring path to provide averaging of the divergence effects of the medium in the flow direction.

Abstract: A system for frequency locking the output of one or many laser amplifiers to a reference laser oscillator beam without injection of the reference beam into the amplifier medium. This avoids the necessity of exciting at the frequency of the desired output and of beam splitting from the oscillator to inject a portion of the oscillator radiation into each of several controlled amplifiers. The amplifier includes a lasing medium confined within a cavity and having a portion of the radiation in the medium directed onto a closed loop. A frequency selecting element is supplied within the closed loop and controlled electronically to maintain a predetermined frequency relationship to the laser beam of the reference laser oscillator. Radiation in the closed loop is thus controlled in frequency and a portion of it within the amplifier medium is diverted for repeated medium traversals in an unstable cavity configuration to achieve a desired amplification and pulse elongation.