Zygo wins Virgo upgrade order

04 Mar 2013

High-precision optics to feature in upgrade to “Virgo” project designed to test Einstein’s theory of gravitational waves.

Precision optics and metrology company Zygo Corporation has won what it calls “a substantial order” to manufacture a series of very high precision components for the European Advanced Virgo project.

The project is an upgrade of the Virgo gravitational wave detector located near Pisa in Italy, which was completed in 2003. The second-generation instrument should gain an order of magnitude improvement in sensitivity compared with the existing setup, and be able to explore a volume of universe 1,000 times larger.

Its ultimate goal is to detect gravitational waves that, according to the theories of Albert Einstein, originate from giant cosmic events like collisions between black holes.

Frank Nowak, optical products manager at subsidiary ZygoLOT in Germany, said: "We have a long tradition in manufacturing large optics with sub-nanometer specifications for gravitational wave detection that utilizes similar manufacturing technology offered to our semiconductor lithography customers."

Raffaelle Flaminio, director of the Laboratoire des Materiaux Avances (LMA) and responsible for the procurement of Virgo’s optics, confirmed that Zygo would be the sole supplier, saying: "After a comprehensive evaluation of many potential suppliers worldwide, the LMA has selected Zygo as the key, and only, supplier of optics for our Advanced Virgo program. We look forward to interacting with their world class team throughout the duration of this program."

The optical components will be manufactured by Zygo's Precision Optics and Extreme Precision Optics groups in Middlefield, CT and Richmond, CA.

Extreme sensitivity required
Virgo is one of a number of gravitational-wave detectors that have been constructed around the world to test Einstein’s predictions – though none has yet been able to directly detect the phenomenon.

Projects such as Virgo and the US-based Laser Interferometer Gravitational-Wave Observatory (LIGO) are designed to use high-precision interferometry to detect the waves. They feature a pair of “light storage” arms – kilometres long – that are predicted to change in length when a gravitational wave passes through.

Virgo features a Michelson interferometer design, and its two arms are both 3 km long - although by using multiple reflections the effective optical path length is as high as 120 km.

Because of the extreme sensitivity required to detect the waves, the interferometer mirrors must be fabricated from high-purity materials, and have very low heat absorption at the laser wavelength used.

Japan’s Large-Scale Cryogenic Gravitational Wave Telescope (LCGT) features a high-purity sapphire optical blank made by GT’s Crystal Systems subsidiary.