Abstract: A method and apparatus for quality control of laser shock processing. The method includes measuring emissions and characteristics of a workpiece when subjected to a pulse of coherent energy from a laser. These empirically measured emissions and characteristics of the workpiece are correlated to theoretical shock pressure, residual stress profile, or fatigue life of the workpiece. The apparatus may include a radiometer or acoustic detection device for measuring these characteristics.

Abstract: A method and apparatus for quality control of laser shock processing. The method includes measuring emissions and characteristics of a workpiece when subjected to a pulse of coherent energy from a laser. These empirically measured emissions and characteristics of the workpiece are correlated to theoretical shock pressure, residual stress profile, or fatigue life of the workpiece. The apparatus may include a radiometer or acoustic detection device for measuring these characteristics.

Abstract: A method and apparatus for quality control of laser shock processing. The method includes measuring emissions and characteristics of a workpiece when subjected to a pulse of coherent energy from a laser. These empirically measured emissions and characteristics of the workpiece are correlated to theoretical shock pressure, residual stress profile, or fatigue life of the workpiece. The apparatus may include a radiometer or acoustic detection device for measuring these characteristics.

Abstract: Atoms in a neodymium:glass rod 20 are excited to a substantially spatially uniform metastable state by flashlamps 21. A flowing fluid 26 cools the flashlamps, but not the rod; so that low temperature gradients are maintained in the rod during isothermal laser operation. Automatic control means 22 turn off the electrical power supply 24 when the temperature in the rod reaches a predetermined limit. A flowing fluid 23 then cools the rod, at a rate low enough to avoid thermal stress therein, while it is not lasing. Segments of reflectors 25 focus the pump photons in the rod so as to substantially balance the cylindrical lensing action of the rod against the radial attenuation through it, and thus to provide substantially uniform density of stored energy in the rod.

Abstract: Methods and apparatus for improving properties of a solid material in a target (11) by providing shock waves therein. There are directed to the surface of the material (11) pulses of coherent radiation (12) having average energy fluence of at least about 10 Joules per square centimeter and rise time of not longer than about 5 nanoseconds within a fluorescence envelope lasting about 0.5 to 5 milliseconds, at a rate of about 1 radiation pulse per 100 to 200 microseconds.The leading edge of each pulse (12) is sharpened by providing in its path an aluminum film (18) about 150 to 5000 angstroms thick that is vaporized by the pulse and then is moved across the path so that a later pulse (12) strikes an area of the film (18) not already vaporized by an earlier pulse (12).The radiation (12) is amplified by an amplifier (23) comprising a rod of phosphate laser glass that was strengthened by an ion exchange process.

Abstract: Apparatus for improving properties of a solid material by providing shock waves therein. A laser oscillator 10a provides a plurality of pulses 112 of coherent radiation. The leading edge of each pulse is sharpened either by a metal foil 18 or by phase conjugation reflection means 18a, 18e including a stimulated Brillouin scattering cell 18d,18e and optionally a Faraday isolator 18b. Each pulse is directed onto an amplifier 123 comprising first and second laser amplifier rods 23a,23b in series. At least a major portion of the radiation 112 amplified by the first amplifier rod 23a is directed to the second amplifier rod 23b, where it is amplified and then directed to a surface of the solid material.

Abstract: Apparatus 10 (FIG.

Abstract: Apparatus for providing X-rays (11) to an object (12) in air. A lens (13) directs energy (14) from a laser (27) onto a target (15) to produce X-rays (11) of a selected spectrum and intensity. A substantially fluid-tight first enclosure (16) around the target (15) has a pressure therein substantially below atmospheric pressure. An adjacent substantially fluid-tight second enclosure (18) contains helium (24) at about atmospheric pressure. A wall (19) has an opening (20) large enough to permit X-rays (11) to pass through and yet small enough that gas (21) can be evacuated from the first enclosure (16) at least as fast as it enters through the opening (20) at the desired pressure. Intermediate enclosures (34, 34') at logarithmically increasing air pressures have similar openings (20', 20") in line with the opening (20) and a transparent portion (36) in the near wall (35) of the second enclosure (18).

Abstract: Apparatus (10) for obtaining fluorescence laser EXAFS (Extended X-ray Absorption Fine Structure). A lens (12) directs a pulse of radiant energy (13) onto a metal target (15) to produce X-rays (16). A baffle (17) directs the X-rays (16) onto a spectral-dispersive monochromator (18) which directs the spectrally-resolved X-rays (16R) therefrom onto a sample (11). Fluorescence X-rays (27) from the sample (11) strike a phosphor (26) on a grid (19). Emitted light (21) from the phosphor (26) corresponds spatially to the spectral resolution of the X-rays (16R). Emitted light intensity at a point along the spatial distribution corresponds to the absorption characteristics of the sample (11) at a particular wavelength of the incoming X-rays (16R). An imaging lens (20) directs the emitted light (21) onto photographic film or an array detector (22).

Abstract: Apparatus (10) for obtaining EXAFS data of a material (11). A lens (12) directs a pulse of radiant energy (13) from a laser (14) onto a metal target (15) to produce X-rays (16) of a selected spectrum and intensity at the target (15). A baffle (17) directs X-rays (16) from the target (15) onto a spectral dispersive monochromator (18) which directs the spectrally resolved X-rays (16R) therefrom onto a photographic film 20. A film of material (11) is located in the path (22) of only a portion (16L) of the X-rays (16) throughout a selected spectral band, and the resolved X-rays (16R) directed onto the photographic film (20) form two separate images thereon comprising a reference spectrum (26R) representative of a portion of the X-rays (16U) throughout the selected band that was not affected by the film of material (11) and an absorption spectrum (26A) representative of a portion of the X-rays (16L) throughout the selected band that was modified by transmission through the film of material (11).

Abstract: A two-step method for separating mineral grains from their ores is practised by first applying a shock discharge directly through the ore sample producing shock waves emanating from along the discharge path and reflected shock waves (tension waves) from grain boundaries and other discontinuities in the ore, such tension waves resulting in tensile stresses in the ore greater than the strength of the boundary or discontinuity whereby to gross spall the sample generally along the discharge path and to microfracture the region near the discharge path. The second step comprises comminuting the microfractured ore by impact or non-impact means to further reduce the ore generally along microfractures wherein considerably less energy is expended in the second step than would be required to reduce the ore to the same condition without the first step.

Abstract: Method and apparatus for applying radiation by producing X-rays of a selected spectrum and intensity and directing them to a desired location. Radiant energy is directed from a laser onto a target to produce such X-rays at the target, which is so positioned adjacent to the desired location as to emit the X-rays toward the desired location; or such X-rays are produced in a region away from the desired location, and are channeled to the desired location.The radiant energy directing means may be shaped (as with bends; adjustable, if desired) to circumvent any obstruction between the laser and the target. Similarly, the X-ray channeling means may be shaped (as with fixed or adjustable bends) to circumvent any obstruction between the region where the X-rays are produced and the desired location.For producing a radiograph in a living organism the X-rays are provided in a short pulse to avoid any blurring of the radiograph from movement of or in the organism.

Abstract: Methods and apparatus for directing radiation pulses to a region wherein either a pulse or a substance in the region is adversely affected by the presence of more than a given power density therein. A laser pulse is split into a plurality of portions and each portion is directed along a path of different length to provide in rapid succession a plurality of pulses each having less than the given power density. Each pulse is caused to arrive at the region at an angle differing by at least its divergence angle from the arrival angle of every other pulse (or, if at a smaller angle from another pulse, with opposite polarization therefrom) and at a time enough later than the arrival time of the preceding pulse that the total power density in the region at any instant is less than the given power density. Thus, the effective total power density of the radiation directed through the region may exceed the given power density without adversely affecting any pulse or substance in the region.

Abstract: A method of producing X-rays by directing radiant energy from a laser onto a target. Conversion efficiency of at least about 3 percent is obtained by providing the radiant energy in a low-power precursor pulse of approximately uniform effective intensity focused onto the surface of the target for about 1 to 30 nanoseconds so as to generate an expanding unconfined coronal plasma having less than normal solid density throughout and comprising a low-density (underdense) region wherein the plasma frequency is less than the laser radiation frequency and a higher-density (overdense) region wherein the plasma frequency is greater than the laser radiation frequency and, about 1 to 30 nanoseconds after the precursor pulse strikes the target, a higher-power main pulse focused onto the plasma for about 10.sup.

Abstract: Methods and apparatus for directing a radiation pulse from a laser to a target or other selected location and preventing undesired earlier radiation from the laser having less than a selected intensity from reaching the selected location.A beam splitter directs a major portion of the radiation pulse energy along a longer main path to a predetermined region and continuing on toward the selected location, and directs a minor portion along a shorter secondary path to the predetermined region. A reflective surface on a transparent support in the predetermined region prevents energy having less than the selected intensity from continuing on toward the selected location.