Optical Surfaces Delivers Parabolic Mirrors for Petawatt Laser

Optical Surfaces Ltd. has delivered three parabolic mirrors to Rutherford Appleton Laboratory for use in the Gemini petawatt laser.

Optical Surfaces manufactured a very fast parent f/0.6 parabola from which three fast-focusing off-axis parabolic mirrors with a diameter of 175 mm, surface accuracy of better than λ/8 P-V, surface quality of 20/10 scratch/dig, and surface slope error of λ/10/cm P-V were produced.

Technicians work on the Rutherford petawatt laser. Courtesy of the STFC Rutherford Appleton Laboratory.

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 copropagation of a much longer focal length beam, enabling a range of additional science to be explored.

"Due to tight operational constraints, the delivery of the [off-axis parabola] with the hole had to be within a specific timeframe," said Aris Kouris, sales manager at Optical Surfaces. "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 was successful and we managed to deliver it within the requested timeframe.”

A fast-focusing off-axis parabolic mirror. Courtesy of Optical Surfaces Ltd.

The Gemini laser delivers high-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, allowing experiments that can't be attempted elsewhere.

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 the Science & Technology Facilities Council operates the Rutherford Appleton Laboratory in Didcot, England.

Optical Surfaces has been producing optical components and systems for more than 50 years.