A US specialist in cleaning processes for cleanroom equipment, JST Manufacturing, has designed a cleaning system for the optics used by the National Ignition Facility (NIF), the high-energy laser system at Lawrence Livermore National Laboratories (LLNL) in California.
Each of NIF’s 192 beamlines has around 50 optics to focus the laser beams. To maintain the large inventory of optics, LLNL partnered with JST Manufacturing to develop a unique cleaning tool.
‘If these lenses were not as clean as possible then we would start to degrade the performance of our laser,’ explained Patrick Williams, NIF optics maintenance manager. ‘The cleanliness of our optics is crucial to our ability to produce maximum fluency that is required to perform many tests.’
One of the innovations in the NIF cleaning tool, which was a tank-like configuration, was to eliminate the need to move the optics to different locations in order to perform the washing, rinsing and drying functions.
‘The optics are heavy and rather large, so we don’t want to handle them a lot,’ Williams said. ‘Our engineers suggested that rather than transport these heavy optics for such functions, we could simply transport the chemistry to the optics in a fixed location,’ explained Louise Bertagnolli, president of JST Manufacturing. ‘We also designed a sling-like device to hold the optics and also let technicians rotate them during the inspection process.’
To date, JST has built two cleaning tools for NIF. The first tool was used for the very beginning of the facility. ‘A second tool was built to provide us with dual capacity,’ Williams said. ‘Because NIF has become a production facility, where many scientists and companies are performing research, we also wanted to be able to clean a higher volume of optics and also get away from single-point failure.’
There is also other experimental work ongoing at the UK’s Central Laser Facility to improve the damage threshold of the optics used in these high-energy laser facilities.