A major technological milestone in optical glass melting has been achieved by Hoya Corporation USA, a laser glass manufacturer in Fremont, California. Hoya is using a novel continuous glass melting system (approximately 150 feet long and two stories high) to produce 20 tons of high quality laser glass per month. To date, the system has produced more than 600 neodymium-doped laser amplifier glass slabs for Lawrence Livermore National Lab's National Ignition Facility (NIF) in Livermore, California and 125 slabs for Laser Megajoule Project (LMJ), a French government facility currently under construction in Bordeaux, France.
Each laser glass slab, which measures 790 mm by 440 mm and is 45 mm thick, is carefully fine annealed and extensively tested and inspected in Hoya Corporation's new 32,000 square-foot laser glass manufacturing facility in Fremont. The glass produced by Hoya's continuous melting system has successfully achieved all of the stringent glass specifications required for NIF and LMJ. In particular, the glass contains essentially no microscopic platinum particles that could cause laser-induced damage within the glass at NIF and LMJ's high operating fluence. In addition, the "water" (OH) content in the glass is less than 200 ppm thus minimizing Nd fluorescence quenching. Finally, the optical homogeneity surpasses the transmitted wavefront specification by about a factor of two.
"Hoya's work in this area is outstanding," said Ed Moses, NIF project manager. "Along with the glass slabs produced by Schott Glass Technologies, roughly half of the total glass slabs needed for NIF have been produced. "This technological achievement is significant. Our goal was for Hoya to produce 500 glass slabs during their current melting campaign - they've exceeded that by 50 percent."
Hoya's current continuous glass melting campaign, which began in June 2000, will end as planned in February 2001. Beginning in Summer 2001, Hoya will begin to produce the remaining laser glass needed to supply their 50 percent share of the amplifier slabs required for NIF and LMJ. Schott is to provide the other 50 percent. It is anticipated that between Hoya and Schott, approximately 1500 slabs will be produced annually. The combined amount needed for NIF and LMJ is about 8000 laser slabs.
"We appreciate the opportunity to work with LLNL and the French Government on these very important projects," said Gerald Bottero, President and Chief Executive Officer of Hoya Corporation USA. "We've worked with this special glass since 1973 and we commend our employees for their dedication and commitment to perfecting this technology."
Hoya was founded in 1941 as Japan's first specialty manufacturer of optical glass. The company is the world's leading supplier of molded aspheric lenses for cameras, VCRs and DVD players, and operates a state-of-the-art melting facility in Akishima, Japan. In addition, Hoya offers glass magnetic disks, semiconductor photomask blanks, eyeglasses, contact lenses and a variety of other products through 46 subsidiaries in 22 countries.
Hoya is headquartered in Tokyo, Japan and expects fiscal year 2000 sales to exceed $2.3 billion. Hoya maintains a Web site at http://www.hoya.co.jp .
The National Ignition Facility, currently under construction at Lawrence Livermore National Lab, is one of the cornerstones of the Department of Energy's Stockpile Stewardship Program. NIF will use the world's largest laser to heat fusion fuel to thermo-nuclear ignition.
The experiments will help scientists sustain confidence in the nuclear weapons stockpile without actual testing. NIF will also produce additional benefits in basic science and fusion energy. Further information can be found at http://www.llnl.gov/nif