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A method using synchrotron radiation parallel beam x-ray optics with a small incidence angle α on the specimen and 2Θ-detector scanning is described for depth profiling analysis of thin films. The instrumentation is the same as used for Θ:2Θ synchrotron parallel beam powder diffractometry, except that the specimen is uncoupled from the detector. There is no profile distortion. Below the critical angle for total reflection αc, the top tens of Angstroms are sampled. Depth profiling is controlled to a few Angstroms using a small α and 0.005° steps. The penetration depth increases to several hundred Angstroms as α approaches αc. Above αc there is a rapid increase in penetration depth to a thousand Angstroms or more and the profiling cannot be sensitively controlled. At grazing incidence the peaks are shifted several tenths of a degree by the x-ray refraction and an experimental procedure for calculating the shifts is described. The method is illustrated with an analysis of iron oxide films.

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An investigation of thermal lensing effects in longitudinally diode-pumped Nd:YVO 4 lasers is made in detail both numerically and experimentally. A finite-element model is used to theoretically simulate thermal lensing in various Nd:YVO 4 crystals and pumping scenarios. The predicted values for thermally induced lens strengths are compared with experimentally observed results. We find that these two sets of results are in broad agreement, provided that the spatial profile of the pump-induced heat generation is accurately modeled. The saturation of the pump absorption is found to be of particular importance in producing an accurate prediction of the thermal lens strength, and a composite structure of the crystals is desirable to relieve the thermal lensing.Index Terms-Composite crystal, diode-pumped laser, Nd:YVO 4 , thermal effect, thermal lensing.

An effective and novel technique for improving the biocompatibility of a biograde 316 LS stainless steel through the application of CO(2) laser treatment to modify the surface properties of the material is described herein. Different surface properties, such as surface roughness, surface oxygen content, and surface energy for CO(2) laser-treated 316 LS stainless steel, untreated, and mechanically roughened samples were analyzed, and their effects on the wettability characteristics of the material were studied. It was found that modification of the wettability characteristics of the 316 LS stainless steel following CO(2) laser treatment was achieved. This improvement was identified as being mainly due to the change in the polar component of the surface energy. One-day cell adhesion tests showed that cells not only adhered and spread better, but also grew faster on the CO(2) laser-treated sample than on either the untreated or mechanically roughened sample. Further, compared with the untreated sample, MTT cell proliferation analysis revealed that the mechanically roughed surface resulted in a slight enhancement, and CO(2) laser treatment brought about a significant increase in cell proliferation. An increase in the wettability of the 316 LS stainless steel was observed to positively correlate with the cell proliferation.