We have a “new” (used) Nd:YAG pulsed laser (labelled Nd:YAG B in the photo below) that can produce up to 600 mJ of 1064 nm light in 6 ns pulses which we frequency double to 532 nm to pump our Radiant Dyes Narrowscan laser. The dye laser has a high-power, narrow bandwidth (5 GHz), near infra-red (730-750 nm) output.
As before, the 1064nm output of the “old” Nd:YAG (labelled as Nd:YAG A) is doubled to 532 nm and the sum-frequency of the first and second harmonic is used to generate 170 mJ of 355 nm light. This third harmonic pumps the Sirah Cobra-Stretch laser (another dye laser), which outputs broadband (85 GHz) 486 nm pulses that are then doubled to 243 nm (UV).
The 243 nm UV photons can resonantly excite ground-state Positronium into the 2P state; the excited atoms can then be driven to high-n Rydberg states with our infra-red laser (see Ref 1).
The laser systems (A and B) are completely independent, so we can easily fine-tune the timing of the two and optimise the two-step excitation process.
 Selective Production of Rydberg-Stark States of Positronium. T. E. Wall, A. M. Alonso, B. S. Cooper, A. Deller, S. D. Hogan, and D. B. Cassidy, Phys. Rev. Lett. 114, 173001 (2015) DOI:10.1103/PhysRevLett.114.173001.