This from Astronomy.com:

The Keck interferometer on Mauna Kea, Hawaii. The interferometer consists of two telescopes each with a 10 meter reflecting mirror, made up of 36 hexagonal mirrors on computer controlled actuators for pinpoint accuracy (4 nano-meters), in separate domes, about 279 feet (85 meters) apart.  Photo Credit: W. M. Keck Observatory.

Twin Keck 30 Meter Observatories at Sunset, Mauna Kea, Hawaii

Note the observing shutters have been opened and are facing east, so when the first objects to be observed come up over the horizon, the telescopes will be able to track them immediately. Interferometry has two great observing advantages. First, using two telescopes twice the amount of light coming from the object is captured. Second, just like having two eyes, each image is that tiny bit from a different perspective, giving the telescopes a kind of stereo vision and that allows for the computer processing the image to add in a great more detail.  The observatory to the left of the two Kecks is the Subaru 8.2 meter optical/infrared telescope operated by Japan.

Cutaway View of Twin Keck Domes and Astronomy Center

From the Astronomy.com article:

An exquisite look at black holes

The Keck Interferometer directly resolves the accreting material around supermassive black holes in galactic nuclei. Provided by Max Planck Institute, Bonn, Germany. December 8, 2009

“An international research team presents some of the first long-baseline interferometric measurements in the infrared towards nearby active galactic nuclei with the Keck Interferometric Telescope in Hawaii. The team, led by Makoto Kishimoto from the Max Planck Institute for Radio Astronomy in Bonn, Germany, found the measurements to indicate a ring-like emission from sublimating dust grains and its radius to yield insights into the morphology of the accreting material around the black hole in these nuclei.”

Cutaway Diagram of the Keck 10 Meter Telescope with Annotations

For more photos of the Kecks and their observing gallery, click here.

Photos Courtesy of the W.M. Keck Observatory.