Mindrum Precision Inc. machines its clear and colored filter multioptical lenses to tight 0.00001-in. tolerances and bonds these lenses together in flow cells that become integrated into lasers, computers, medical devices and other applications requiring exacting performance. The company's high quality standards meant that it had to scrap as much as 20 percent of its lens assemblies because of the formation of bubbles in the adhesive layer after curing. A high-clarity UV-curing adhesive from Loctite Corp., 349 Impruv, reduced Mindrum's scrap rate to less than 5 percent.Loctite's 349 Impruv UV-curing adhesive provided optical clarity and reduced the formation of bubbles between Mindrum Precision's lens assemblies. Courtesy of Loctite Corp."In a lot of cases, we bond six or seven layers of glass," said Rick Adams, Mindrum's production control manager. "We have to experiment setting up the lenses at the same time, applying the cement, keeping out air bubbles. Loctite's adhesive worked real simply the first time around." Previous products sampled by Mindrum required some trial and error before achieving the right process. Loctite's 349 Impruv is a one-part adhesive that cures within seconds with the application of ultraviolet light. Adams said that, once cured, the adhesive provides optical clarity for Mindrum's lens systems. The company also tamper-proofs its lens assemblies by bonding stainless steel screws into the glass or sapphire. The epoxy used previously required five to 10 minutes of mixing prior to being applied. Mindrum reduced this process time to 5 to 10 s using another bonding product from Loctite, Prism 410. Like 349 Impruv, Prism 410 is a single-component instant adhesive that bonds in small or large gaps. "The quality of our process improved immediately," Adams said. "We ... used Prism 410, and it worked real well from the start."