Many aspects of geometric optics and wave optics are compatible with the finite element method of analysis. This fact provides a new and powerful tool in the fields of optomechanical design and optical systems engineering. Using special features available in some commercially available finite element codes, it is possible to include optical system parameters as a portion of the finite element model. The simultaneous solution of the optical and mechanical problems provides higher accuracy and consistency of the results, efficient calculation of many different load cases, and solutions to optics design problems which are difficult or impossible to handle in traditional lense design codes. This paper shows results possible in commercially available finite elements codes used to calculate optical system parameters, including surface figure changes, generalized optical ray tracing and wavefront error computation. The paper is illustrated with examples drawn from recent practice.