Mirrors and other optical elements are disclosed that include a body defining an optical surface (typically a reflective surface) and an opposing second surface. The body has a coefficient of thermal expansion (CTE). The optical element includes a correcting portion (e.g., a layer) attached to the second surface and having a CTE that, during heating of the optical element, imparts a bending moment to the body that at least partially offsets a change in curvature of the optical surface caused by heating. The body can be internally cooled. The body and correcting portion desirably are made of respective thermally conductive materials that can vary only slightly in CTE. The body desirably has a lower CTE than the correcting portion, and the correcting portion can be tuned according a variable property of the body and/or reflective surface. The body and correcting portion desirably function cooperatively in a thermally bimetallic-like manner.