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Proceedings Paper

LGSD/NGSD: high speed optical CMOS imagers for E-ELT adaptive optics
Author(s): Mark Downing; Johann Kolb; Philippe Balard; Bart Dierickx; Arnaud Defernez; Philippe Feautrier; Gert Finger; Martin Fryer; Jean-Luc Gach; Christian Guillaume; Norbert Hubin; Paul Jerram; Paul Jorden; Manfred Meyer; Andrew Payne; Andrew Pike; Javier Reyes; Robert Simpson; Eric Stadler; Jeremy Stent; Nick Swift
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Paper Abstract

The success of the next generation of instruments for ELT class telescopes will depend upon improving the image quality by exploiting sophisticated Adaptive Optics (AO) systems. One of the critical components of the AO systems for the E-ELT has been identified as the optical Laser/Natural Guide Star WFS detector. The combination of large format, 1760×1680 pixels to finely sample the wavefront and the spot elongation of laser guide stars, fast frame rate of 700 frames per second (fps), low read noise (< 3e-), and high QE (> 90%) makes the development of this device extremely challenging. Design studies concluded that a highly integrated Backside Illuminated CMOS Imager built on High Resistivity silicon as the most likely technology to succeed. Two generations of the CMOS Imager are being developed: a) the already designed and manufactured NGSD (Natural Guide Star Detector), a quarter-sized pioneering device of 880×840 pixels capable of meeting first light needs of the E-ELT; b) the LGSD (Laser Guide Star Detector), the larger full size device. The detailed design is presented including the approach of using massive parallelism (70,400 ADCs) to achieve the low read noise at high pixel rates of ~3 Gpixel/s and the 88 channel LVDS 220Mbps serial interface to get the data off-chip. To enable read noise closer to the goal of 1e- to be achieved, a split wafer run has allowed the NGSD to be manufactured in the more speculative, but much lower read noise, Ultra Low Threshold Transistors in the unit cell. The NGSD has come out of production, it has been thinned to 12μm, backside processed and packaged in a custom 370pin Ceramic PGA (Pin Grid Array). First results of tests performed both at e2v and ESO are presented.

Paper Details

Date Published: 23 July 2014
PDF: 8 pages
Proc. SPIE 9154, High Energy, Optical, and Infrared Detectors for Astronomy VI, 91540Q (23 July 2014); doi: 10.1117/12.2055407
Show Author Affiliations
Mark Downing, European Southern Observatory (Germany)
Johann Kolb, European Southern Observatory (Germany)
Philippe Balard, Lab. d'Astrophysique de Marseille (France)
Bart Dierickx, Caeleste (Belgium)
Arnaud Defernez, Caeleste (Belgium)
Philippe Feautrier, Institut de Planétologie et d’Astrophysique de Grenoble (France)
Gert Finger, European Southern Observatory (Germany)
Martin Fryer, e2v technologies plc (United Kingdom)
Jean-Luc Gach, Lab. d'Astrophysique de Marseille (France)
Christian Guillaume, Observatoire de Haute-Provence (France)
Norbert Hubin, European Southern Observatory (Germany)
Paul Jerram, e2v technologies plc (United Kingdom)
Paul Jorden, e2v technologies plc (United Kingdom)
Manfred Meyer, European Southern Observatory (Germany)
Andrew Payne, e2v technologies plc (United Kingdom)
Andrew Pike, e2v technologies plc (United Kingdom)
Javier Reyes, European Southern Observatory (Germany)
Robert Simpson, e2v technologies plc (United Kingdom)
Eric Stadler, Institut de Planétologie et d’Astrophysique de Grenoble (France)
Jeremy Stent, e2v technologies plc (United Kingdom)
Nick Swift, e2v technologies plc (United Kingdom)

Published in SPIE Proceedings Vol. 9154:
High Energy, Optical, and Infrared Detectors for Astronomy VI
Andrew D. Holland; James Beletic, Editor(s)

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