Infrared detector development programs for the VLT instruments at the European Southern Observatory

Instrument platforms like the VLT represent a new challenge to infrared focal plane technology. Since the large telescope diameter and the improved image quality provided by adaptive optics reduce the pixel scale, larger array formats are needed. To meet this challenge ESO is participating in development programs for both InSb and HgCdTe large format arrays. To cover the spectral region of I to 5 micron ESO has funded a foundry run at SBRC to produce 1024x1024 InSb arrays, which will be installed in ISAAC, the Infrared Spectrometer and Array Camera built for the VLT. Since the delivery of the 1Kx1K InSb array is delayed, the test results obtained with a 256x256 InSb array and the application of off chip cryogenic amplifiers to InSb detectors will be discussed. Results obtained with a lambda(c)=2.5 mu m Rockwell 1024x1024 HgCdTe array will be presented, where an off chip cryogenic operational amplifier was used yielding a rms read noise of 3 electrons. Sensitivity profiles of individual pixels have been measured with a single mode IR fiber. Limitations of PACE 1 technology, such as persistence, will be discussed. First results with the 1Kx1K array, which was installed in SOFI, an infrared focal reducer providing 1-2.5 micron imaging and long slit grism spectroscopy at the NTT telescope, will be presented. Advanced techniques of real time image sharpening will also be included. An outlook to the development of lambda(c)=2.5 mu m 2048x2048 HgCdTe array formats will be given. The optical layout of NIRMOS, a multi-object spectrograph for the VLT telescope, is based on the availability of 2Kx2K HgCdTe arrays.