Temperature stable optical bonding method and apparatus

Optical elements (52, 54) are bonded to supports (58) by a resilient bonding agent (68) and a rigid bonding agent (78). The resilient bonding agent has the property of shrinking upon curing and is placed within a bonding space (66) defined by rails (64) of a rail assembly (56). Upon curing, the bonding agent shrinks and securely pulls the contacting surfaces (52b, 64a) of the element and the rails under tension of the bonding agent. A donut (80) of resilient material spaces the bonding agent from contact with or adjacent to the contacting surfaces (64a, 52b) so that, for a rail assembly and an optical element of significantly different coefficients of thermal expansion, temperature variations will not cause glass pieces to be pulled from the optical element. The base (62) of the rail assembly is also made thin to bend and provide relief upon contraction of the bonding agent rather than to unduly stress the optical element.