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Dark Energy Spectroscopic Instrument Project Delivers Major Optical Elements

DESI Corrector Lens, C1, measuring 1.15m in diameter

The Dark Energy Spectroscopic Instrument (DESI) project has delivered major optical elements to Arizona Optical Science and L3-Brashear for figuring and polishing. Above is an image of the largest corrector lens, C1 measuring 1.15m in diameter. The homogeneity of the fused silica glass came in at an astounding 1ppm (exceeding the 3ppm spec). C1 and C4 are about to be packed up and shipped from Corning to L3-Brashear. L3-Brashear was recently selected to figure and polish C1 and C4. Arizona Optical Sciences is already at work on C2 and C3. DESI expects all four of these lenses to be completed through polishing by the end of 2015.

The Dark Energy Spectroscopic Instrument (DESI) will measure the effect of dark energy on the expansion of the universe. It will obtain optical spectra for tens of millions of galaxies and quasars, constructing a 3-dimensional map spanning the nearby universe to 10 billion light years.

DESI will be conducted on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018. DESI is supported by the Department of Energy Office of Science to perform this Stage IV dark energy measurement using baryon acoustic oscillations and other techniques that rely on spectroscopic measurements.