4-5 November 2013, 2013 Annual NAHEL Meeting, LULI, Palaiseau, France

Venue: "Salle de Conseil", Institut d'Optique

For directions, please see 'how to reach LULI' and the campus plan.

Agenda:

- Facility updates (CLF, GSI, PALS, LULI)
- Discussion session 1: Interfacing devices to the Control system
- Discussion session 2: Beam alignment and propagation issues
- Presentations for upcoming facilities and European laser projects
   * ELI-Beamlines and the ELI pillars
   * The Spanish Petawatt Laser Facility
   * Wavefront control and compensation of prompt pump-induced aberrations
- Discussion session 3: Wavefront control and compensation of prompt pump-induced aberrations
- Discussion session 4: Laser System Performance Diagnostics
- Discussion session 5: Optics issues for large scale infrastructure

The 2013 Networking Activity on High Energy Lasers (NAHEL) Workshop was organized by the Laboratoire l'Utilisation des Lasers Intenses (LULI) and held in the Salle du Conseil, Institut Optique (Palaiseau, France) on 4-5 November 2013. The workshop was attended by over thirty participants from France, Germany, the UK, Spain, Portugal, and the Czech Republic.

This meeting was organized in three parts: two oral presentation sessions, five discussion sessions, and lab tours. The first oral presentation session was devoted to the current status of the facilities and updates on development projects given by representatives of each of the working group members (LULI, CLF, GSI and PALS). The second one focused on the new and upcoming facilities (Orion, Salamanca and ELI). These two sessions were followed by five discussion sessions covering a wide range of technical topics. Each session was presided over by a chair who gave a kick-off talk introducing a series of questions to guide the discussion. The first of these sessions was about how devices used in the laser facilities, such as cameras, motor drivers, oscilloscopes and delay generators, can be controlled with the facility's control system. Several device interfaces, such as Ethernet, USB, RS, and FireWire were discussed.

The second session was about beam alignment. Among other things, it was discussed whether the beams should be aligned by technical staff or by the scientists themselves, and to what extent the alignment could be automated. Another topic discussed in this session was about beam propagation, including optical delay lines, the impact of deformable mirrors, and compensation of chromatic aberration.

Another session was about wavefront control and focal spot quality. Central to this discussion was how to measure the focal spot of the laser beam (using either commercial sensors or home-made ones), and how to improve the quality of the focal spot using deformable mirrors and adaptive optics. The fourth discussion session was dedicated to diagnostics of the laser system performance, which was started with a summary of the about characterisation of ultra-short high energy laser pulses organised by CLF in September 2013.

The final discussion involved the peculiarities of optics for large scale infrastructures. Among other things, optics under vacuum can be affected by oil contamination, leading to lower reflectivity and damage threshold. Possible cleaning procedures were discussed, as well as damage thresholds for various optical elements and p-polarized light. Finally, the ultimate optical quality for large scale optics was touched upon, since for the next generation of large scale laser infrastructures the size of the optics will be close to one meter.

The workshop concluded with tours of the LULI laser facilities (LULI2000, ELFIE, LUCIA project).

Organiser: Ji Ping ZOU, LULI