Challenging Focusing Mirror Expands Scope of Rutherford Petawatt Laser

Optical Surfaces Ltd. has delivered three challenging off-axis parabola of 175mm diameter to the UK's prestigious Rutherford Appleton Laboratory

Using a new technique – Optical Surfaces highly experienced and skilled production team manufactured a very fast parent F 0.6 parabola from which 3 fast focusing off-axis parabolic mirrors with surface accuracy of better than lambda/8 P-V, surface quality of 20/10 scratch/dig and surface slope error of lambda/10/cm P-V were produced.

The world class Gemini laser based at the Rutherford Appleton Laboratory, delivers Petawatt power laser pulses to targets only a few microns in size. The temperatures, pressures and magnetic fields at the laser focus reach levels that otherwise exist only inside stars, making Gemini a unique facility for scientists to conduct experiments that cannot be attempted anywhere else.

Laser-plasma interactions under these conditions can produce energetic beams of electrons and protons as well as bright, coherent sources of X-rays and can also address fundamental questions in astrophysics and plasma physics. The laser focus is routinely generated with the use of precise parabolic focusing optics, which can only be made by a few companies in the world.

The order for the most recent focusing optic was tendered and awarded to Optical Surfaces Ltd. The key focusing mirror was particularly challenging as it was required to have a hole through the optic, on the focusing axis. This hole facilitates the co-propagation of a much longer focal length beam enabling a whole range of additional science to be explored.

To enable a range of new experiments on their Gemini laser, Rutherford ordered three off-axis paraboloids - one with a slanted conical hole in the centre and two without a hole.  Due to tight operational constraints the delivery of the OAP with the hole had to be within a specific timeframe.

For this reason, and due to the very demanding specification for this optic, we developed a new manufacturing technique that enabled us to speed up the manufacturing time of the parent parabola significantly. The method has successful and we managed to deliver it within the requested timeframe.

Dr Aris Kouris - Optical Surfaces Ltd

Optical Surfaces Ltd has been producing optical components and systems for more than 50 years and is now accepted as one of the world’s leading manufacturers of high-precision optics for high power laser research facilities.

The company’s ISO 9001-2008 approved manufacturing workshops and test facilities are deep underground in a series of tunnels excavated in solid chalk where temperature remains constant and vibration is practically non-existent. With such stable conditions testing, particularly with long path lengths, becomes quantifiable and reliable. Working with these natural advantages is a highly skilled team of craftsmen with a commitment to excellence in both product quality and customer service.

For further information relating to Central Laser Facility at the STFC Rutherford Appleton Laboratory please visit here

For further information relating to diffraction limited parabolic mirrors please visit here

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