Aerospace Engineering at Illinois Prof. John Lambros
and his PhD student, Owen Kingstedt
, have managed a scientific first in producing real-time, high-speed imaging of a laser strike onto a thin aluminum film.
The accomplishment, potentially helpful in designing microelectronics materials by visualizing thin film debonding as it happens, has won for Lambros and Kingstedt the 2017 Society of Experimental Mechanics M. Hetényi Award. The scientists’ research paper, entitled “Ultra-high Speed Imaging of Laser-Induced Spallation,” was chosen as the best research paper published in 2015 in SEM’s flagship journal, Experimental Mechanics.
Lambros and Kingstedt, now an assistant professor at the University of Utah, were able to precisely configure their experiment to capture images of the damage to a thin aluminum film while laser loading was in progress over a time frame of 35 nanoseconds.
“In the past we had looked at the damage caused to the thin aluminum film after the laser strike, but in this work we wanted to look at it in real time with very high time resolution,” Lambros said. “(The experiment) took photos of the failure event every 5 nanoseconds, or at 200 million frames per second. In this experiment there is a lot of information about what is happening as it happens.
Captured images of the spallation event
“What makes this difficult is synchronizing everything. We had 35 billionths of a second to catch the event as it was happening,” he continued. “The main purpose for this experiment is to look at the strength and failure of microelectronics films – how strong they are and when do they fail.”
This is Lambros’ second Hetényi award from SEM; he and AE Prof. Ioannis Chasiotis and their students won in 2012 for investigating the strain rate dependence of nanocrystalline Pt films.
An AE faculty member since 2000, Lambros has simultaneously garnered SEM’s 2017 P.S. Theocaris Award, which recognizes a senior individual for distinguished, innovative and outstanding work in optical methods and experimental mechanics.
Lambros noted that his PhD advisor, A.J. Rosakis, professor at the California Institute of Technology, had been a previous recipient of the Theocaris Award, one of the society’s highest honors. The recognition is made only of an existing SEM Fellow, and only once every two years.
Lambros has been an SEM Fellow since 2013, and is also a Fellow of the American Society of Mechanical Engineers and of the American Academy of Mechanics.