Beam Transport

NIF Laser Bay
Each NIF laser bay is 122 meters (400 feet) long and contains 96 beamlines. This side view of Laser Bay 2 shows the four-high laser transport beamline enclosures above the preamplifier support structure.

As NIF’s laser beams are propagated four times through the main amplifier and twice through the power amplifier, their energy is boosted to about 4 megajoules of infrared laser light.

Within the laser beam enclosures are two stages of spatial filters that condition the beams after amplification. Before being transported to the Target Chamber, each beam is focused through a series of tiny, millimeter-sized pinholes and recollimated in NIF’s spatial filters. These pinholes are located at the center of the huge beam tubes that create a vacuum environment so the laser beams can be concentrated into such a small spot size without ionizing the air molecules.

NIF Deformable Mirror
Deformable mirrors, located at the ends of NIF’s main amplifiers, use an array of 39 actuators to create a movable surface that corrects aberrations in a beam due to minute distortions in the optics.

Passing the beams through the pinholes eliminates scattered laser light, creating smooth, high-quality beams capable of meeting stringent performance requirements at high power and energy.


After the laser beams leave the laser bays, they enter the switchyards, which redirect the beams to the upper and lower hemispheres of the Target Chamber. The switchyards convert the parallel laser beam layout to the spherical configuration of the Target Chamber so they converge radially on the target.

The beams travel through the switchyards in groups of four called “quads.” With the help of several series of transport mirrors, 24 beam quads are redirected to the upper portion of the Target Chamber and 24 are redirected to the bottom portion. Four mirrors are required to accomplish this, along with a fifth mirror for one-third of the beams because of geometric constraints. The mirrors are specially coated and conditioned to survive NIF’s high-energy laser environment. They are also designed to be extremely stable in the vibration and thermal environment of the huge NIF facility so that the laser beams can hit the target with a precision of better than 50 micrometers—about the thickness of a piece of paper.

Next Up: Final Optics