Abstract

The change of focal length with temperature of a radial gradient index lens is modeled using finite differences. It is found that the gradient and homogeneous contributions to the focal length change can be balanced against each other for a net change of zero. It is important to emphasize that using this method, these athermalized solutions can be found for single element lenses even when using materials with high expansion coefficients, i.e., polymers. A double graphing technique is developed which visually identifies these athermalized solutions by comparing the effect of the gradient and homogeneous contributions to the focal length change. An athermalization coefficient for the special case of a flat surfaced radial gradient index lens (Wood lens) is derived and presented in simplified form.

© 1989 Optical Society of America