Adaptive Optics for Extremely Large Telescopes 4 – Conference Proceedings
State of the art IR cameras for wavefront sensing using e-APD MCT arrays
- Author(s): Feautrier, Pilippe
- Gach, Jean-Luc
- et al.
Published Web Locationhttps://doi.org/10.20353/K3T4CP1131556
The recent discovery of electron initiated avalanche photodiodes (e-APDs) using mercury cadmium telluridesemiconductor materials has permitted a significant advance in short-wave infrared imaging. In the visible spectrum,electron-multiplying charge-coupled devices (EMCCDs) improved imaging techniques—especially in the life sciences.And yet, no significant breakthroughs have been made in infrared imagery since the hybridization of III-V or II-VIsemiconductors with low bandgap on complementary metal-oxide semiconductor (CMOS) read-out integrated circuits(ROICs).In 2012, Philippe Feautrier et al. and Gert Finger et al.  of the European Southern Observatory (ESO; Garching,Germany) reported successful hybridization of HgCdTe e-APDs on CMOS ROICs with a significant number of pixels(320 × 256). Feautrier et al.  also reported the use of a Sofradir/CEA-LETI APD array on the ESO Very Large TelescopeInterferometer (VLTI), called RAPID, demonstrating for the first time the successful operation of this technology in arepresentative environment.First Light Imaging  is the first commercial company to make e-APD infrared array technology available in its C-REDOne camera. Using a 320 × 256, 2.5 μm cutoff wavelength HgCdTe e-APD array deeply cooled to 80 K with a highreliabilitypulse-tube cryocooler (mean-time between failure or MTBF of approximately 90,000 hours), the camera has ahigh readout speed of 3500 frames/s (full frame) while exhibiting a readout noise below one electron—thanks to the APDgain in the range of 1 to 60.This paper reports on the results of the Sofradir/CEA-LETI RAPID program  and on the development of the C-REDone infrared camera from First Light Imaging based of the SELEX SAPHIRA detector . The interest of ShortWavelengths InfrRed (SWIR) e-APD versus more classical HgCdTe arrays as infrared tilt sensors or pyramid wavefrontsensor like what is currently developed at Keck Observatory is also discussed in this paper.