Atherm Editorial

I took a graduate class and then worked with Dan Vukobratovich. He had an interesting approach to passive athermalization. To paraphrase a hallway conversation:

“The lens designer should ignore thermal effects when designing his lens. The lens designer should focus on minimizing aberrations at ambient conditions. It is my [the opto-mech engineers] job to provide an athermal structure. If the optical designer worries about thermal aberrations, he will be unable to control all aberrations over temperature. Consequently one could be left with thermal dependent spherical aberration”.
- Dan Vukobratovich

Indeed a lens designer can go to herculean efforts to eliminate thermal defocus only to see his optical performance still degrade with temperature due to thermal spherical aberration. This is a complicated subject and it is beyond the scope of this discussion. Still...

I believe it is the lens designers responsibility to minimize thermal defocus.
Otherwise the opto-mech engineer may be left to design multi-material structures out of un-obtanium to keep the system in focus.