Volume VII–System Description
OMEGA EP Operations Manual
Page 1 of 35
G6967J1
Upper
compressor
OMEGA EP grating compressor chamber
Target chambers
Beam
combiner
TC
selector
Lower
compressor
Sidelighter
periscope
Sidelighter
Backlighter
OMEGA
OMEGA EP
oriented Brewster’s angle plate or polarizer. Support structures mounted on the laser bay floor house the
fold mirror, the PEPC, polarizers, and the cavity end mirror.
The components of the beamline are interconnected with nitrogen-filled beam tubes. The nitrogen
in these tubes prevents oxygen from degrading the internal silver reflecting surfaces of the amplifiers
at the ends of the main and booster amplifiers and maintains the low-percent RH working environment
required by the coatings on the polarizers. The tubes and amplifiers are positively pressurized to ~0.1 in.
of H
2
O and a temperature, percent-oxygen and percent-RH monitoring system provides an out-of-
specification alarm in the Control Room.
1.5.1 Beam Transport
Depending on the individual beamline and experimental conditions, the amplified pulse emerging
from the transport spatial filter may take one of several paths, as shown in Fig. 1.7. For short-pulse
experiments, Beam 1 or Beam 2 may be routed to the upper or lower compressor in the GCC, where
four matched MLD tiled grating assemblies temporally compress the pulse. A deformable mirror after
the fourth tiled grating assembly provides static wavefront correction. After passing through individual
compressors, the beams are co-aligned through a polarizing beam splitter called the beam combiner.
Beam 1 is reflected off this optic in s-polarization while Beam 2 is transmitted in
p
-polarization. The
co-aligned beams are routed to one of the target chambers using the target chamber selection mirror
and focused using an
f
/1.8 off-axis parabolic mirror. Transport from the GCC is in an evacuated beam
transport tube connected to the target chamber being used.
Alternatively, after the compressed pulses reflect off their respective DM, the beams may be
independently and simultaneously directed to the OMEGA EP backlighter and sidelighter (see Fig. 1.4).
The beam from the upper compressor may be directed to the backlighter and the beam from the lower
compressor may be sent to the sidelighter. This capability allows for stereoscopic viewing of target
experiments. This capability does not exist for the OMEGA target chamber as there is only one beam
transport tube. The flow chart below and Fig. 1.7 illustrate this concept.
Summary of Contents for Volume VII-System Description
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