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A unique tool

The strategy for the construction of the Megajoule Laser (LMJ) has four main thrusts:

A large-scale project

After the completion of the preparatory works stage in 2002 (earthworks and installation of the road system and service networks), construction began in 2003 and the building was finished in 2008. The first experiments are planned for late 2014.

As many as 1,200 people were involved in the project at any one time and worked on extremely varied tasks. The priority for CEA's Military Applications Division (DAM), the owner and site manager for the entire project, is worker safety and protection of the environment, a key concern that was addressed right from the design stage of the building (undertaken in accordance with the ISO 14001 environmental management standard).

The building's dimensions give an idea of the scale of the project:

  • 300 meters (~984 feet) long;
  • 100 meters (~328 feet) wide;
  • 50 meters (~164 feet) high (above-ground height: 35 meters).

Its construction required the use of more concrete and reinforcement materials than used to build the Millau viaduct.

The building has 140,000 m² of floor space, of which 40,000 m² are ISO 7 and ISO 8 clean rooms. Four 100 × 30 m laser halls have been built to house the laser equipment. The building also contains an experimental hall measuring 60 meters in diameter.


The equipment of the building, which was sized to house 240 beams, includes:

  • 10,000 optical devices;
  • 10,000 motors;
  • 2,000 cameras;
  • 2 metric tons of single crystals;
  • 300 metric tons of glass.

Extreme technical requirements

The building and its associated services have been designed and built primarily to meet two requirements of its use:

  • A very high degree of stability to ensure alignment of the laser beams and the diagnostic equipment;
  • A very high degree of cleanliness, as dust accelerates lens aging and leads to increased running costs.

The air-handling facility guarantees the required level of cleanliness and temperature stability to within one-half of one degree. It filters and regulates the temperature and humidity levels of five million cubic meters of air per hour.

The facility has a capacity of 50 MW.

MàJ: 20/11/2014
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