X Arm End Station
View the panorama named "Rooftop" and you'll see that the X arm of LIGO Hanford's H1 detector forms the clockwise leg of the site's 90 degree layout. This panorama provides a view of the interior of the end station that terminates the path of the laser beam along H1's X arm. Notice that the beam tube does not protrude from the rightmost chamber -- you've reached the end of the detector. The vacuum chambers visible in the photo are identical to the chambers tha you can see in the "LVEA Infrasound Detector" panorama.
No equipment rests inside the rightmost chamber, which formerly held the terminal mirror for LIGO's H2 detector -- a second detector that operated at LIGO Hanford during the Initial LIGO era. H2 underwent a complete upgrade in the Advanced LIGO program along with H1 and L1, but the components for this new third detector remain in storage at LIGO Hanford, waiting to cross the ocean to be built into a fully operational LIGO interferometer at a location in India.