No strangers to dark energy, we are proud to be involved in machining the cast Invar components for a new spectroscopic instrument designed to measure the spectra of more than 30 million galaxies and quasars covering 14,000 square degrees over a five year period.

The Dark Energy Spectroscopic Instrument (DESI), which is mounted on the Mayall telescope at Kitt Peak National Observatory in Arizona, USA, began its five year operating life last year.

Astronomers use the term ‘dark energy’ to describe the unknown form of energy hypothesised to be responsible for the constant expansion of the universe. Scientists such as DESI hope to be able to learn more about the nature of dark energy in an attempt to help us better understand the universe.

Cast Invar components

We opted to use Invar to cast the components for the instrument due to its unique properties:

Low thermal expansion

The key reason Invar is so popular as a component for the likes of telescopes and microscopes is its low thermal expansion properties. This means that unlike other alloys, it is able to maintain between temperatures of -100°C & 260°C without changing shape. Even small changes can have a huge impact on the accuracy of results, so being able to use a material which isn’t impacted is a huge bonus.


Invar’s low thermal expansion also means it is an incredibly durable material. In fact, it’s a popular choice for transporting liquid natural gases due to the significant insulation it provides.


This combined makes Invar the primary industry choice for machining parts where a high level of accuracy is required. Its stability as an alloy mean it is unrivalled in applications such as clock pendulums (where it was originally used), optical engineering and precision instruments, as well as a variety of scientific instruments.