High-quality optic increases laser intensity at Rutherford Appleton Laboratory

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Optical Surfaces has delivered a high-quality F0.8 on-axis parabola of 175mm diameter to the Central Laser Facility at the STFC Rutherford Appleton Laboratory. The optic will be used to focus a laser beam at the facility to extremely high intensities for experiments into laser-matter interactions.

Peta Foster, Astro Gemini Link Scientist, commented: 'Our primary aim is the production of the highest intensity ever produced with a laser. This optic was extremely demanding in specification and we are delighted to take receipt of it. The focus of this optic should deliver a five times increase in laser intensity that we hope will enable the study of an exciting new regime in laser-matter interactions.'

Due to be installed on the Astra Gemini laser beam line, the diffraction limited on-axis mirror will be used to focus the beam line energy to produce a maximum focused intensity of c. 1021Wcm-2 enabling researchers to explore new areas of physics.

Using proprietary production techniques, Optical Surfaces highly experienced and skilled production team produced the fast focusing on-axis parabolic mirror with a surface accuracy of better than lambda/10 P-V and smoothness of 20/10 scratch/dig. The excellent surface quality achieved during manufacturing together with the exceptional high reflectivity coatings will enable RAL researchers to achieve the high optical performance and efficiency required by their experiments.

The optics were manufactured in Zerodur and coated using a special type high-performance UV-silver coating suitable for high reflectivity (R>98 per cent) throughout the wavelength range between 350-800nm.

Dr Aris Kouris of Optical Surfaces commented: 'We were delighted to have again been selected by a world-class laser facility to produce optics key to their future research. In this project the great challenge was to achieve the targeted surface accuracy and local gradients simultaneously for such a highly aspheric mirror (0.4mm of asphericity) and of this size. The higher the asphericity and the smaller the size of the optic the more difficult is to control both optical performance parameters but especially the local gradients. This is due to the fact that the gradients are changing directions very rapidly over a short distance making it extremely challenging to achieve. Optical performance at that level requires mastering of technical and practical aspects at multiple levels.'

The Central Laser Facility (CLF) at the STFC Rutherford Appleton Laboratory (RAL) is one of the world's leading laser facilities providing scientists from the UK and Europe with state-of-the-art laser technology. The CLF's wide ranging applications include experiments in physics, chemistry and biology, accelerating subatomic particles to high energies, probing chemical reactions on the shortest timescales and studying biochemical and biophysical process critical to life itself.