A simple adhesion process has been developed for applying glass lenses to the active surfaces of Si and GaAs optical devices such as detectors and solar cells . The method, which uses a film of fluorinated ethylene propylene (FEP) offers reliability, cost and throughput advantages over the conventional dimethyl silicone adhesive. Critical to the process is the ion bombardment of individual surfaces before assembly. The resulting enhanced adhesion suggests some modification of surface properties. Four possible mechanisms are briefly discussed. The technique is believed to have broad applicability to amorphous and crystalline semiconductor systems and devices other than those under test.