Before revision: A changing thermal environment can cause an optic to bend due to either 1) thermal gradients on the optic and a non-zero coefficient of thermal expansion, or 2) coefficient of thermal expansion gradients in an optic and a temperature change.
After revision: A chan averagechangingnging thermal environment can cause an optic to bend due to either 1) thermal gradients on the optic and a non-zero coefficient of thermal expansion, or 2) coefficient of thermal expansion gradients in an optic and a temperature change.