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 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: 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.