Vulcan Laser refocuses on electron acceleration experiments

09 Jan 2013

New mirror improves research potential of UK-based high energy laser.

The Central Laser Facility at the STFC Rutherford Appleton Laboratory (RAL) in Didcot, UK, has taken delivery of an ultra-high precision off-axis parabolic mirror from Optical Surfaces.

The mirror will form a crucial focusing element in RAL's ongoing experimentation using the Vulcan Nd:Glass High Energy Laser.

Trevor Winstone, Operations Manager for the Vulcan Laser at RAL commented, "We will use the F/15 off-axis parabola for experiments that require long Rayleigh focal length such as electron acceleration.”

The advance in laser technology to ultra-high intense (>1018Wcm^-2) short-pulse (<1ps) lasers has made it possible to study laser-plasma interactions at ultra-high intensities.

Applications include particle acceleration, inertial confinement fusion reactions and biological and medical technologies. He added, "We selected Optical Surfaces Ltd to supply this precison focusing optic because of the company’s track record in manufacturing and supplying high quality, demanding optics to ultra high power laser facilities worldwide."

Quality focus

Optical Surfaces’ production team produced the 320mm diameter off-axis parabolic mirror with a surface accuracy of better than lambda/8 P-V, achieving a surface gradient better than lambda/20 P-V and smoothness of 20/10 scratch/dig.

This surface quality achieved during manufacturing together with the exceptional high reflectivity coatings will enable RAL researchers to achieve the optical performance and efficiency required by their experiments. The off-axis mirror was manufactured in ClearCeram HS and coated using a special high performance coating to achieve reflectivity (R>99%) at both 1053nm and 527nm.

Dr Aris Kouris of Optical Surfaces commented, “The most demanding part of the producing this demanding optic was to achieve the surface gradients which required an iterative process in order to achieve the required smoothness.

“To achieve lambda/20 P-V surface gradients specification using an iterative process added a significant amount of handling during the manufacturing that increased the risks for markings. Fortunately our skilled craftsmen are highly experienced in handling optics and maintaining a very high surface quality.”

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 an unparalleled range of 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.

About the Author

Matthew Peach is a contributing editor to optics.org.