Electronic Materials Inc. has released Optocast 3580 and 3590 curable epoxies with refractive indexes of 1.4823 and 1.550, respectively. They contain no monomers, have no odor and are nontoxic. These clear, low-viscosity liquids cure to a tough, resilient plastic with a high D hardness of 85 and 84. They contain no solvents, which eliminates the need for a special exhaust system. UV epoxy chemistry and other curing mechanisms allow the adhesive to be cured between substrates that are either completely opaque or functionally opaque to UV light.