We demonstrate an inner surface profile measurement that has a smooth spatial distribution. A supercontinuum beam suppresses the speckle contrast to 22% and the standard deviation of the point cloud to 40%, compared to equivalent values obtained by use of a conventional green He-Ne laser at a wavelength of 543.5 nm. A compact probe for the inner surface profile measurements using the supercontinuum beam measures the depth removed by wear of a small hole in an automobile component. The radial spatial resolution was evaluated to be 2 μm, which was of the same order as the wavelength of the supercontinuum beam. The supercontinuum beam enables fivefold improvement of the radial spatial resolution compared to the monochromatic wavelength beam because of a reduction in speckle effects.
XUV spectra of 150 ps laser-produced samarium (Sm) plasmas in the 1.8-10 nm wavelength region, where Δn=1, n=4−n=5 and Δn=0, n=4−n=4 transitions dominate the observed emission, were investigated experimentally and theoretically. Ab initio calculations using the flexible atomic code, as well as consideration of isoelectronic trends, are all employed to identify a number of new features in spectra from Sm 16+ to Sm 34+ . The results show that Δn=0, n=4−n=4 emission from highly charged ions merge to form an intense unresolved transition arrays in the 7.5 nm region and Δn=1, n=4−n=5 resonance transitions contribute in the 3-7 nm region of the Sm spectrum. In addition, a number of strong individual lines at shorter wavelengths are seen to arise from Cu-and Zn-like ions and a number of new assignments are made for Zn-like Sm 32+ .
We have characterized the soft x-ray and extreme ultraviolet (XUV) emission of rhodium (Rh) plasmas produced using dual pulse irradiation by 150-ps or 6-ns pre-pulses, followed by a 150-ps main pulse. We have studied the emission enhancement dependence on the inter-pulse time separation and found it to be very significant for time separations less than 10 ns between the two laser pulses when using 6-ns pre-pulses. The behavior using a 150-ps pre-pulse was consistent with such plasmas displaying only weak self-absorption effects in the expanding plasma. The results demonstrate the advantage of using dual pulse irradiation to produce the brighter plasmas required for XUV applications.
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