Teledyne e2v, the UK subsidiary of Teledyne Technologies, has delivered 125 of its high-performance CCD sensors to the site of the Large Synoptic Survey Telescope (LSST) in Chile.
The 8.4 meter diameter optical telescope, which is nearing completion at the summit of Cerro Pachó, is due to carry out a decade-long survey of the night sky following the expected “first light” milestone in 2021.
Infrared efficiency
At the heart of the telescope’s design is a three-mirror optical system to ensure an extremely wide field of view, and a huge 3.2 gigapixel light sensor constructed from nearly 200 of Teledyne e2v’s 16 megapixel (4096 by 4004 pixel format) CCDs.
The result will be the largest digital camera ever built for ground-based astronomy, say the project partners. Once up and running, it is expected to capture 1000 images every night, creating a database of some 37 billion stars and galaxies over the course of a decade.
“e2v’s CCD sensors have been uniquely designed and manufactured to achieve the performance and delivery time required for this project,” announced the UK firm. “The 16 megapixel sensors have been manufactured in a custom 4-side butting precision package that enables a closely packed mosaic assembly providing a high fill factor.”
Since the camera requires an extremely flat focal surface, each of the individual sensors has been produced with extreme surface flatness precision. They also offer high sensitivity over a wide wavelength range, including a quantum efficiency of 80 per cent at 900 nm – an important part of the spectrum for infrared astronomy.
The sensors also feature 16 output channels, enabling a two-second readout with low read-noise, meeting the requirements for LSST’s high rate of high-resolution image collection.
Site arrivals
Paul Jorden, astronomy product specialist at Teledyne e2v, said in a company release: “We are thrilled to have partnered with SLAC National Accelerator Laboratory in the US to deliver what are among the world’s most powerful image sensors, tuned to a level of performance and exacting standards we are so pleased to have achieved. We anticipate superb results of this very important ground-based astronomy system.”
LSST director Steve Kahn added: “During its ten-year survey, LSST will capture images of billions of never-before-seen astronomical objects, generating unprecedented amounts of data and helping to answer some of the universe’s biggest questions. The benefits produced by LSST will extend far beyond the astronomy community.”
The CCD sensors arrived at the telescope site in a key year for its construction. At SPIE’s Astronomical Telescopes and Instrumentation symposium, held earlier this year in Austin, Texas, said that around $100 million worth of equipment would arrive over the coming year.
Around a month ago a huge optical coating chamber was delivered, while its secondary mirror - believed to be the largest convex mirror ever produced - is currently en route to the summit, having arrived in Chile December 7. It was made by contractor Harris Corporation.
LSST’s combined primary/tertiary mirror is still undergoing tests at the University of Arizona’s UA’s Richard F. Caris Mirror Lab, and is expected to arrive at the summit site next summer.
Supported by the US National Research Council, LSST will seek to answer fundamental questions about dark matter, dark energy, near-Earth asteroids, transient optical objects including supernovae, and the formation of the Milky Way galaxy once it begins operations.
