Optical System Alignment

Educational Series:

Factors That Influence Thermal Focus Shift: A Thin Lens Model

As a supplement to Deriving a Passive Athermalization Figure of Merit for Length Comparison, this video explores the effect of thermal expansion and refractive index on a thin lens' thermal focus shift. Different classes of lens materials are then compared using this simple equation.

Deriving a Passive Athermalization Figure of Merit for Length Comparison

Infrared optic lens materials present a unique challenge to opto-mechanical design. In this video, we derive a Figure of Merit (FOM) that describes a commonly used passive solution to the infrared optic negative thermal focus shift problem. This FOM is used in subsequent videos to compare the performance of different optic housing materials.


Length Effects of Materials

The choice of housing materials for athermalizing infrared optics can drastically change the length of the optic. This video uses a previously derived Figure of Merit (FOM) to estimate the length of a passively athermal housing based on housing material selection. A 40% reduction in length is realized by replacing Aluminum with ALLVAR Alloy 30 in the commonly used Aluminum-Delrin material pair.



Negative Thermal Expansion Components for use in IR Optics

Dr. James Monroe at AR/VR/MR 2020

Jeremy McCallister Discusses ALLVAR at AR/VR/MR


ALLVAR Alloy Constant Force Washer Demonstration

Thermal Focus Shift: ALLVAR Alloy-30 Versus Other Metal