December 26, 2005, Surrey, England--Optical Surfaces Ltd. has been selected to supply two high precision mirrors to the Central Laser Facility at the renowned Rutherford Appleton Laboratories (Didcot, UK) for the Astra Gemini project. The mirrors will be critical beam focusing components that will help increase the intensity of the existing Astra laser by three orders of magnitude.
The Astra Gemini project is funded by a CCLRC £3million grant in a development that will create the most intense laser in the world. The new development will provide the UK with a unique dual-beam facility, delivering a total power of 1 petawatt. The development will, when completed in 2007, 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 make best use of this enhanced power the highest quality achievable off-axis parabolic focusing mirrors are required to maximize beam intensity while keeping the target outside the beam aperture.
The first stage of the mirror fabrication will be to produce, in Zerodur, a single 460mm diameter, f 0.62 on-axis parabolic parent. From this Optical Surfaces Ltd. will use its proprietary, flexible lapping technology and uniquely stabilised production environment to produce two 175mm diameter, f1.9 off-axis parabolic mirrors.
Typical specifications achieved by Optical Surfaces Ltd's highly experienced and skilled team of engineers and craftsmen include off-axis parabolic mirrors up to 600 mm in diameter with surface accuracy's to lambda/20 p-v depending upon off-axis angles. With proprietary polishing techniques Optical Surfaces can, depending on the surface accuracy required, achieve the natural limit to the off-axis angle of around 25-30 degrees and surface micro-roughness on aspherics of ~ 1 nm rms.