November_December_2021_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 2 1 1 3 photoelectron spectroscopy is com- bined with x-ray light sources, precise measurements with specific atomic selection are possible. “Our approach opens up a vari- ety of exciting new developments,” the researchers say. “This ranges from extending our method for simultaneous energy- and angle-resolved electron measurements to experiments with x-rays to obtain atom-specific informa- tion.” As another benefit of their new approach, the sensitivity of the multi- dimensional spectroscopy experiments has been improved by orders of magni- tude. The increased sensitivity allows for the study of very clean samples in an ultrahigh vacuum environment. www. uni-freiburg.de/en. CONTACTLESS DAMAGE DETECTION A collaborative research team from Shibaura Institute of Technology and Photron Ltd., Japan, developed a novel framework for the generation and detection of zero-order symmetrical mode Lamb waves in transparent mate- rials. First, the team had to find a suit- able technique to generate Lamb waves without damaging the sample. They leveraged a previously used approach to generate mechanical oscillations in a contactless way—laser-induced plasma shock waves. Next, the researchers measured the generated waves with a high-speed polarization camera. This polarization contains informa- tion directly related to the material’s mechanical stress distribution, which in turn reflects the propagation of Lamb waves. To put their strat- egy to the test, the team created micro- scopic scratches on a few flat, transparent polycarbonate plates and compared the propagation of Lamb waves on damaged and pristine sam- ples. As predicted, the scratches caused noticeable differences in the stress distribu- tion of the plates as the waves propagated over the damaged areas, demonstrating the potential of this novel approach by detect- ing scratches measuring only several dozen micrometers. According to the researchers, this nondestructive dam- age detection scheme could help reduce the production costs of high- quality transparent materials, though further studies are warranted. www.shibaura-it.ac.jp/en. Nondestructive Lamb waves are captured on a transparent plate produced by shock waves from a laser-induced plasma. Courtesy of Prof. Naoki Hosoya/SIT.