text: In the early 1990s, the market was becoming more familiar with the potential of laser peening to increase fatigue life. In 1991, the U.S. Air Force introduced Battelle and Wagner engineers to GE Aviation to discuss the potential application of laser peening to address a foreign object damage (FOD) problem with fan blades in the General Electric F101 engine powering the Rockwell B-1B Lancer Bomber. The resulting tests showed that laser peened fan blades severely notched after laser peening had the same fatigue life as a new blade. After further development, GE Aviation licensed the laser shock peening technology from Battelle, and in 1995, GE Aviation and the U.S. Air Force made the decision to move forward with production development of the technology. GE Aviation began production laser peening of the F101 fan blades in 1998.
  The demand for industrial laser systems required for GE Aviation to go into production attracted several of the laser shock peening team at Battelle to start LSP Technologies, Inc. in 1995 as the first commercial supplier of laser peening equipment. Led by founder Jeff Dulaney, LSP Technologies designed and built the laser systems for GE Aviation to perform production laser peening of the F101 fan blades. Through the late 1990s and early 2000s, the U.S. Air Force continued to work with LSP Technologies to mature the laser shock peening production capabilities and implement production manufacturing cells.
  In the mid 1990s, independent of the laser peening developments ongoing in the United States and France, Yuji Sano of the Toshiba Corporation in Japan initiated the development of a laser peening system capable of laser peening welds in nuclear plant pressure vessels to mitigate stress corrosion cracking in these areas. The system used a low-energy pulsed laser operating at a higher pulse frequency than the higher powered lasers. The laser beam was introduced into the pressure vessels through articulated tubes. Because the pressure vessels were filled with water, the process did not require a water overlay over the irradiated surface. However, the beam had to travel some distance through the water, necessitating using a shorter wavelength beam, 532 nm, to minimize dielectric breakdown of the beam in the water, instead of the 1054 nm beam used in the United States and France. Also, it was impractical to consider using an opaque overlay. This process is now known as Laser Peening without Coating (LPwC). It began to be applied to Japanese boiling water and pressurized water reactors in 1999.
  Also in the 1990s a significant laser peening research group was formed at the Madrid Polytechnic University by José Ocaña. Their work includes both experimental and theoretical studies using low-energy pulsed lasers both without and with an opaque overlay.