First e2v CCDs for Gaia
29 September 2003The first batch of CCD wafers for Gaia's Astro (AF) instrument has recently been completed at the UK headquarters of e2v technologies in Chelmsford.
The CCD91-72s represent one of the largest area CCDs produced by e2v. They are nearly 50% bigger than e2v's successful astronomy products used worldwide in ground-based telescopes. The Gaia device is designed to work in TDI (Time Delay and Integrate) mode. This allows an integrated image to be built up by the continuously scanning satellite, an essential concept at the heart of Gaia's mission to map with unprecedented accuracy the space position and motions of over a billion stars.
Under contract to EADS-Astrium (Toulouse) to design and manufacture custom designed chips for both the Astro and Spectro instruments on Gaia, e2v is also working with EADS-Astrium to develop advanced packaging techniques using the unique Silicon Carbide capability of EADS-Astrium. These techniques are necessary to achieve the alignment accuracy required across the huge focal plane in order to allow the TDI concept to work. At approximately 0.5 metre square the Astro focal plane of CCDs will be the biggest ever flown in space.
The 32 high performance, large format imaging devices that will be delivered to EADS-Astrium over the next 10 months will be used to verify the operational concepts in the design of the device. They will also be used in the assembly of a test section of the focal plane to be used in alignment tests.
[Pictured above: part of the team from the e2v wafer fabrication area that has produced the initial batch of CCDs. Back row, left to right: Roy Steward, Gaia CCD Project Manager; Pat Mandell, Wafer Fabrication Operative; Sheila Clift, Photolith Inspector; Alan Bidewell, Wafer Fabrication Operative; Glenn Wood, Wafer Fabrication Manager.
Front Row, left to right: Derek Nunn, Team Leader; Phil Etheridge, Line Engineer; Andy Raine, Inplant Operator
Inset: Two CCD91-72 CCDs on a silicon wafer. Each CCD comprises 4500x1966 pixels each 10x30µm in size. (Small test structures are visible on either side of the CCDs.)]