• L.J. Nevay, G.A. Blair, S.T. Boogert, D.F. Howell, R. Walczak
  JAI, Oxford
• L. Corner, N. Delerue, L.J. Nevay, M. Newman, M. Rosenberger
  OXFORDphysics, Oxford, Oxon

Funding: Work supported by the STFC LC-ABD collaboration and the Commission of the European Communities under the 6th Framework Programme Structuring the European Research Area, contract RIDS-011899

We present the latest results on the development of a high power fibre laser system for the laser-wire project on ILC-like laser based beam diagnostics. The laser consists of a crystal oscillator at ~ 1um that can be synchronised to an external frequency reference followed by chirped pulse amplification in ytterbium doped double clad fibre. This system produces 1uJ pulses in an adjustable burst envelope at a chosen frequency. These pulses are further amplified in a large mode area rod type photonic crystal fibre, allowing amplification to high pulses energies whilst maintaining a single spatial mode. The fibre is pumped in pulsed mode by a specially commissioned 400W diode laser fixed at the absorption peak of ytterbium at 976nm, independent of pumping regime. Pumping in a pulsed mode allows the high energies required for laser-wire at MHz repetition rates to be created without the need for active cooling of the laser. The light is frequency doubled to ~500nm to achieve higher laser-wire resolution.

• A.S. Aryshev, V. Karataev
  JAI, Egham, Surrey
• G.A. Blair, S.T. Boogert, G.E. Boorman, A. Bosco, L.C. Deacon
  Royal Holloway, University of London, Surrey
• L. Corner, N. Delerue, B. Foster, F. Gannaway, D.F. Howell, L.J. Nevay, M. Newman, R. Senanayake, R. Walczak
  OXFORDphysics, Oxford, Oxon
• H. Hayano, N. Terunuma, J. Urakawa
  KEK, Ibaraki

Funding: STFC LC-ABD Collaboration, Royal Society, Daiwa Foundation, Commission of European Communities under the 6th Framework Programme Structuring the European Research Area, contract number RIDS-011899

The KEK Accelerator Test Facility (ATF) extraction line laser-wire system has been upgraded, enabling the measurement of micron scale transverse size electron beams. The most recent measurements using the upgraded system are presented, including the major hardware upgrades to the laser transport, the laser beam diagnostics line, and the mechanical control systems.