UK Firm Making Astra Gemini Mirrors

KINGSTON, England, Jan. 16, 2006 -- Optical Surfaces Ltd., a Surrey, England-based provider of optical components and instruments, will supply two high-precision mirrors to the Central Laser Facility at Rutherford Appleton Laboratories (Didcot, England) for the Astra Gemini project.
The mirrors will be critical beam-focusing components that will help increase the intensity of the existing Astra Gemini laser by three orders of magnitude, from 1019 Wcm-2 in a single beam to 1022 Wcm-2 on target in each of two beams.
The Astra Gemini project, funded by a UK government grant, will create the most intense laser in the world and will provide the UK with a unique dual-beam facility, delivering a total power of 1 petawatt (1000 million million watts). When completed in 2007, it will enable scientists to create and investigate extreme conditions in a controlled way in the laboratory. These conditions include temperatures as high as those found on the surface of the sun and colossal magnetic fields that are found in the polar fields of neutron stars.
To best use this enhanced power, the highest quality achievable off-axis parabolic focusing mirrors are needed to maximize beam intensity while keeping the target outside the beam aperture. Optical Surfaces said the first stage of the mirror fabrication will be to produce, in Zerodur (a glass-ceramic material with a very low coefficient of thermal expansion), a single 460-mm-diameter, f0.62 on-axis parabolic parent. The company will then use its flexible lapping technology to produce two 175-mm-diameter, f1.9 off-axis parabolic mirrors.
Typical specifications achieved by Optical Surfaces include off-axis parabolic mirrors up to 600 mm in diameter with surface accuracies to lambda/20 p-v, depending on off-axis angles. Optical Surfaces said that, depending on the surface accuracy required, it can achieve the natural limit to the off-axis angle of around 25-30 degrees and surface microroughness on aspherics of ~1 nm rms.
For more information, visit: www.optisurf.com