Caltech uses COSMOSM to correct drift in light measuring spectrograph

Company California Institute of Technology (Caltech) Industry Educational Location U.S.A. Product Used COSMOSM™ Type of Analysis Linear Static More Details

The Challenge
Hawaii's dormant Mauna Kea volcano is home to the W.M. Keck Observatory, where astronomers explore the deepest regions of the universe. Operated jointly by the California Institute of Technology (Caltech) and the University of California, the Keck Observatory houses the world's two largest optical and infrared telescopes, Keck I and Keck II, each of which has a segmented hexagonal primary mirror measuring ten meters across. To analyze and record the light collected by these massive telescopes, the observatory uses the Low Resolution Imaging Spectrograph (LRIS), one of several instruments designed by Caltech's Astronomy and Astrophysics Department.

LRIS, a 3,000 pound, six-foot wide tapered cylinder encasing a faint-light instrument, is capable of taking spectra of the universe's most distant objects and capturing their images. Yet, a combination of gravitational torque and stresses induced during the rotation of the instrument have led to small but undesirable drifts of the images or spectra over time. The Caltech team needed to better understand what was happening to avoid making the problem worse. Therein lies the problem- there was no in-house analysis method in place.

"Our analysis was mostly done on paper, using established formulate," explains Associate Mechanical Engineer Tony Grewal. "There were problems in the structure that the analysis done on paper did not catch. The critical need of the department was to have software that could recreate solid geometry and then import it directly into an analysis program."

The Solution
"COSMOSM met this requirement perfectly," Grewal states. "With this software, you can see exactly where your stresses are occurring. The old way of doing it wouldn't tell you that at all-it would only tell you how much things would bend and deflect and what the implications might be, not exactly where and how."

The department boasts that this method of analysis has resulted in a 50 percent time savings, compared to its manual methods.

Grewal believes COSMOSM has made implementing the new design changes efficient and accurate to a degree that could not have been possible with their old techniques.

Summary and Metrics:

• Resulted in a 50% time savings.
• Implemented new design changes efficiently and accurately to a degree that could not have been possible with their old techniques.