What are zero expansion optics?
Zero expansion optics are made from a glass-ceramic. The glass properties are formulated to result in a near zero coefficient of thermal expansion. This means that the glass will not change shape due to changing temperatures and is therefore desirable for use in telescope optics. Some examples of this type of material are Zerodur, Astro-Sital and ULE. These materials are more expensive than Pyrex and for this reason are most often found in research telescopes. Optical Mechanics, Inc. uses zero expansion glass in all of our Nighthawk series telescopes.
