Infrared Arrays at the European Southern Observatory

Abstract

This paper gives an overview of infrared array detectors which have been tested and used at ESO. The performance of arrays using Reticon type readouts, CCD readouts and switched FET multiplexers have been evaluated for both InSb and Hg1−xCdxTe detectors. Performance limitations specific to the NICMOS3 256 × 256 Hg1−xCdxTe detector installed in the ESO infrared array camera IRAC2 are addressed. The first test results with a high well capacity SBRC 256 × 256 InSb array are also presented.Advanced readout techniques for image sharpening tested on a 2.2-m telescope are discussed briefly. A new generation of instruments being built for the VLT, the very large telescope project of ESO, is designed to house large format 1024 × 1024 IR arrays. A fast data acquisition system is currently being developed at ESO. The system is capable of handling the high data rates generated in the thermal infrared by large format low well capacity arrays. It can also cope with the low read noise required for flux levels of ≤ one photon/sec. It will first be installed in ISAAC, the Infrared Array Camera and Spectrometer built for the VLT (Moorwood 1993). The present status of both the detector developments and the data acquisition system is reviewed.

Highlights of IAU Symposium No. 167

“…At this meeting we had the opportunity to hear directly on the status of different projects ( A R C O N from C T I O , SDSU from San Diego, A C E from E S O and the controller for the Italian Galileo telescope) and to witness a lively discussion on the relative merits of transputers and DSP. Equally interesting developments for the control of infrared detectors were reported by Finger et al (1995) (ESO system IRACE) and Glass et al (1995) (The Rutherford-SAAO controller). As a user, my impression is that there is no unique technical solution to the problem of building a fast, flexible C C D controller and the present technology does provide all the necessary tools to do the job.…”

“…Just a few years ago it was possible to speak of two-D detectors for the UV-red wavelength range only. At this meeting we have witnessed presentations on array characteristics from the extreme U V (Bonanno 1995), through the blue-visual range (DOdorico 1995, Jorden and Oates 1995, Iwert 1995and Luppino et al 1995; the infrared 1 to 5 μπι window (McLean 1995, Finger et al 1995, Gilmore et al 1995, Fazio 1995, Glass et al 1995and Ueno et al 1995; the 10 -20 μπι window (Fazio 1995, Gezari 1995 and finally to an array of bolometers to operate at submillimeter wavelengths (Moseley 1995). Field imaging and spectroscopy are now possible across this entire energy spectrum and some of the first exciting astronomical results obtained with these devices have been presented here.…”

“…Arrays of 256 2 pixels, InSb-based by SBRC and NICMOS M C T by Rockwell are now in regular operation at different observatories. Still, their operational characteristics are not yet fully investigated (see the presentation by Finger et al (1995) for a flavor of the present status). Experience with CCDs shows that only by the use by different scientists on different programs can the detector behavior be fully explored and its capabilities well understood.…”

“…Experience with CCDs shows that only by the use by different scientists on different programs can the detector behavior be fully explored and its capabilities well understood. The Shift-and-Add and Weighted SAA techniques to enhance the image quality discussed by Finger et al (1995) and Ueno et al (1995), respectively, are examples of potential, added-value applications of infrared detectors. In the spectroscopy field the user experience with the new arrays is even more limited because to our knowledge there are just two spectrometers based on 256 2 detectors which started operation in 1994 (KSPEC of the University of Hawaii and the upgraded CRSP of N O AO), although many are in the construction phase.…”