text: The beginning of the 1970s saw the first investigations of the effects of pulsed laser irradiation within the target material. L. I. Mirkin observed twinning in ferrite grains in steel under the crater created by laser irradiation in vacuum. S. A. Metz and F. A. Smidt, Jr. irradiated nickel and vanadium foils in air with a pulsed laser at a low power density and observed voids and vacancy loops after annealing the foils, suggesting that a high concentration of vacancies was created by the stress wave. These vacancies subsequently aggregated during post-iradiation annealing into the observed voids in nickel and dislocation loops in vanadium.
  In 1971, researchers at Battelle Memorial Institute in Columbus, Ohio began investigating whether the laser shocking process could improve metal mechanical properties using a high-energy pulsed laser. In 1972, the first documentation of the beneficial effects of laser shocking metals was published, reporting the strengthening of aluminum tensile specimens using a quartz overlay to confine the plasma. Subsequently, the first patent on laser shock peening was granted to Phillip Mallozzi and Barry Fairand in 1974. Research into the effects and possible applications of laser peening continued throughout the 1970s and early 1980s by Allan Clauer, Barry Fairand, and coworkers, supported by funding from the National Science Foundation, NASA, Army Research Office, U.S. Air Force, and internally by Battelle. This research explored the in-material effects in more depth and demonstrated the creation of deep compressive stresses and the accompanying increase in fatigue and fretting fatigue life achieved by laser peening.