Optical Surfaces has delivered a pair of ground-breaking target chamber focusing mirrors for the Astra Gemini dual-beam Petawatt laser facility at the Rutherford Appleton Laboratory (RAL) in the UK
The highly aspheric, f1.6, 175mm diameter off-axis paraboloic mirrors have a focal length of 285mm coupled with an off axis angle of 27deg.
To achieve the demanding specification and close matching, the pair were cut from an f0.6, 450mm diameter Zerodur parent.
Despite the extreme aspheric correction of 1.8mm a form accuracy of lambda/13 and slope errors of less than lambda/10 per cm were achieved, reinforcing the position of Optical Surfaces, as a world leader in the manufacture of large aspheric optics.
The off-axis parabolic mirrors will operate as critical beam focusing components that will help increase the intensity of the existing Astra laser by three orders of magnitude from 10^19Wcm-2 in a single beam to 10^22Wcm-2 on target in each of two beams.
To make best use of this enhanced power the Rutherford Laboratory stipulated state-of-the-art tolerances for the off-axis parabolic focusing mirrors in order to maximise beam intensity while keeping the target outside the beam aperture.
Optical Surfaces was selected, following a tender process, as the supplier for these mirrors due to its technical excellence, reasonable pricing and a proven record in manufacturing and testing large high precision optics for leading plasma physics groups around the world.
Iain Brock, general manager of Optical Surfaces, said: " Through a combination of skilled craftsmen and proprietary production techniques we have achieved the demanding target tolerances required of the target chamber focusing optics".
He added: "We are delighted to have been able to help a world-renowned laboratory like Rutherford move towards its research goals".
Peta Fosterat of the Rutherford Appleton Laboratory commented: "The Astra Gemini Project aims to produce the world's highest focused intensity and these precision mirrors will form a key part in achieving that".
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 1petawatt (1000 million million watts).
The development will, when completed in June 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.
