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Proceedings Paper

Performance limitations of small-format high-speed infrared arrays for active control loops in interferometry and adaptive optics
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Paper Abstract

The detector mounted in the VLTI fringe sensor FINITO is a 256x256 HgCdTe array with a cut-off wavelength of 1.9 micron. The same arrays having cut-off wavelengths of 2.5 micron will be used in the tip tilt sensor IRIS and the PRIMA instrument of the VLT interferometer. The arrays are part of an active control loop with integration times as short as a few hundred microseconds. The fringe tracker FINITO uses only 7 pixels of the array. To take advantage of the four parallel channels of the PICNIC multiplexer, the pixels illuminated in each quadrant are positioned at the same location within the quadrants. A noise analysis of the PICNIC array shows that the main sensitivity limitation of the array is contained in the low frequency part of the noise power spectrum. Similar behaviour has been observed with other infrared arrays. In an effort to optimize the unit cell pixel buffer to achieve high speed and low noise, a prototype multiplexer is being developed at Rockwell for adaptive optics. However, low frequency noise may still be the limiting factor dominating the noise performance of infrared arrays. To overcome this noise barrier, detector architectures have to be envisaged which should allow double correlated sampling on shorter time scales than a full exposure. This might be accomplished by some kind of gate in the IR material which allows charge to be shifted from an integrating well in the infrared pixel to a small sensing node capacitance of the multiplexer unit cell buffer.

Paper Details

Date Published: 29 September 2004
PDF: 11 pages
Proc. SPIE 5499, Optical and Infrared Detectors for Astronomy, (29 September 2004); doi: 10.1117/12.554322
Show Author Affiliations
Gert Finger, European Southern Observatory (Germany)
Roger M. Smith, California Institute of Technology (United States)
Serge Menardi, European Southern Observatory (Germany)
Reinhold J. Dorn, European Southern Observatory (Germany)
Manfred Meyer, European Southern Observatory (Germany)
Leander Mehrgan, European Southern Observatory (Germany)
Joerg Stegmeier, European Southern Observatory (Germany)
Alan F. M. Moorwood, European Southern Observatory (Germany)


Published in SPIE Proceedings Vol. 5499:
Optical and Infrared Detectors for Astronomy
James D. Garnett; James W. Beletic, Editor(s)

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