This drawing shows the interior of the McMath solar telescope. You are looking at only part of telescope which is above ground. The tunnel for the light beam and the observing rooms where the scientific work is done are buried under the mountain. The picture illustrates the light path of the McMath main beam. At the top of the telescope is a 2 meter flat mirror. It is mounted in heliostat which will track the Sun (or stars), and it directs the light down the polar axis 135 meters to a 1.6 meter image forming, concave mirror. This mirror returns the beam back up the tunnel to a 1.5 meter flat which directs the beam into the observing room below. The beam from the 2 meter mirror, (the main beam), produces an image of the Sun about 84 cm in diameter in the main observing room.
The observing room has a 13.5 meter vertical spectrograph which spreads the sunlight into its component colors, and enables astronomers, from around the world, to study the composition, motions and magnetic fields of our nearest star - the Sun. The spectrograph can be seen in this drawing, going straight down into the mountain below the observing room. The observing room also contains a more compact stellar spectrograph is used for night-time use to study stars that are similar to the sun. There is also a laboratory to the east of the telescope
building where the beam may be diverted to do further study of sunlight. In the laboratory, physicists simulate the high temperature solar gas for study.
Focusing of the telescope, and set-up of the light feeds is accomplished by moving the mirrors along railroad tracks in the long tunnel. There are two smaller "auxiliary" telescopes on either side of the main instrument. These can be operated simultaneously. This allows for three different astronomers to work at the same time, with different instruments.
The McMath, named for Robert R. McMath, a Detroit engineer who pursued a life-long interest in the Sun and this observatory on played a major role in the founding of this observatory on Kitt Peak. This the largest solar observatory in the world. It is operated by the National Solar Observatory 24 hours a day for daytime-solar and night time-stellar research programs, carried out by staff and visiting scientists.