Rigid adaptor ring for CTE mismatched optical device components

An optical device assembly within a telescope, a camera or a laser rangefinder, the optical device assembly comprising:

• an optical housing having a cylindrical cavity therein defining an annular inner wall;
• an optical lens having an annular outer peripheral wall and an axially facing end abutment surface, the optical lens made of silicon carbide and configured to be disposed in the optical housing such that the peripheral wall of the optical lens engages the inner wall of the housing;
• an optical device support structure having an annular outer peripheral wall and an axially facing end abutment surface, the support structure made of a metallic material and having a coefficient of thermal expansion (CTE) different from a CTE of the optical lens made of silicon carbide and configured to be disposed in the optical housing such that the peripheral wall of the support structure engages the inner wall of the housing;
• and
• a rigid adapter ring having an annular outer peripheral wall, the adapter ring configured to be disposed in the optical housing such that the peripheral wall of the adapter ring engages the inner wall of the housing, wherein the rigid adapter ring is made of Invar, wherein the rigid adapter ring is disposed between the optical lens made of silicon carbide and the optical device support structure made of the metallic material and within the optical housing, and wherein the rigid adapter ring has a plurality of circumferentially spaced mounting pads on each axial side of the rigid adapter ring that are configured to interface between the CTE mismatched optical lens made of silicon carbide and the optical device support structure made of the metallic material such that the mounting pads engage the respective end abutment surfaces of the optical lens and the optical device support structure, a central web section of the adapter ring extending between each pair of adjacent mounting pads, and a threaded hole extending through each mounting pad and central web section, and wherein the CTE of the rigid adapter ring made of Invar is substantially closer to the CTE of the optical lens made of silicon carbide.