High Power laser optics

High precision On-Axis Paraboloid helps provide one of the first examples of interaction of Ultra-hi

Optical Surfaces Ltd.has provided the Central Laser Facility at the Rutherford Appleton Laboratory (RAL), Didcot, England, with a high precision, fast focussing On-axis Paraboloid of 255mm diameter for use in the short pulse beam of the ultra-high power Vulcan laser.

The RAL Central Laser facility maintains its position as one of the world’s leading laser facilities through the development of state-of-the art high power lasers targeted towards understanding the fundamental interactions of laser light with matter in high electric fields.

Drawing upon 30 years of design and manufacturing experience & benefiting from a stabilised manufacturing environment, Optical Surfaces were able to supply the required large diameter optic with a very short focal length (225 mm). To produce the best quality resultant wavefront Optical Surfaces were also required to produce the mirror with a surface accuracy of better than lambda/15 and surface smoothness of better than 10 Å. As a consequence the Vulcan laser system can produce power levels up to 100 TW in pulses of less than 1 ps into a spot measuring only a few microns in diameter.

Utilising the Paraboloid as the key focussing optic in the short pulse beam of the Vulcan laser, operating at a wavelength of 1053 nm, the group has developed a focussed intensity in excess of 1019 W/ cm2 producing one of the first ever example of laser light interaction with atomic nuclei. Results from the system demonstrate the laser generation of different isotopes.

The research group conducting the experiments is made up from a consortium of UK universities and their work is leading into exciting and previously uncharted area of plasma physics. In addition the new system has opened up the possibility of advances in applications including fusion energy production, x-ray laser probes and the possible next generation particle accelerators where the laser can generate up to four orders of magnitude higher intensity electric field than any existing magnetic accelerators today.

The above mirror, working at around f#1, is not quite our limit. In fact, we are not sure where the limit is! We produce off-axis paraboloids cut from parents which work as fast as f#0.5, though due to high demand, you may need to wait a while.