Motion System Design

Motion controllers aid space exploration

Exploring the deepest corners of space depends on savvy astronomers with access to the right tools, not the least of which are powerful telescopes. A team of scientists at the University of California Observatories (UCO) is in the process of creating the first comprehensive map of the distant universe. Known as the DEEP Project (Deep Extragalactic Evolutionary Probe), the team uses twin 10-meter W.M. Keck telescopes in Hawaii, the Lick Observatory on Mount Hamilton in California, and the orbiting Hubble Space Telescope.

Telescopes collect light emitted from stars or faint galaxies about 14 billion years ago. Detecting and analyzing this light requires advanced mechanical, electronic, and optical instruments, sensors, and software. Many of these instruments, including the DEIMOS spectrograph (Deep Imaging Multi-Object Spectrograph, which is able to magnify the telescope's capacity by a factor of seven for faint-galaxy optical spectroscopy), require precise motion control. Motion controllers from Galil Motion Control, Rocklin, Calif., have been specified for more than 15 years by Barry Alcott, development engineer at UCO, to handle the motion control tasks.

For example, Alcott is using Galil's RIO Pocket PLC to automate portions of the manually operated Hamilton Spectrograph system, the first cross-dispersed spectrograph installed at the Lick Observatory. It operates by having light fed to a grating that sends it in one direction and then immediately feeds it to a prism that disperses it at a 90° angle, resulting in very high-resolution spectra. Alcott configured the multiple I/O points provided by the RIO to automatically control four pneumatic stages used for moving an iodine cell into a beam, opening a light port, moving a mirror into a beam, and opening a mirror cover. The logic control provided by the RIO ensured proper sequencing of events. Automating control of these functions lets astronomers remotely control telescope instruments from a home base, rather than coming to the Mount Hamilton Observatory.

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