Infrared detectors for first generation extremely large telescope instruments and their characterization program

Abstract

The detectors for the three first generation extremely large telescope (ELT) instruments MICADO (Multi‐AO Imaging Camera for Deep Observations), HARMONI (A High Angular Resolution Monolithic Optical and Near‐infrared Integral Field Spectrograph), and METIS (A Mid‐infrared ELT Imager and Spectrograph) cover from the optical to longwave infrared wavelengths. MICADO and HARMONI detector focal planes require 17 H4RG (Hawaii‐4RG) near‐infrared whilst the METIS focal planes consist of 5 SWIR (shortwave infrared) detectors and one longwave infrared detector. Procurement of the optical and SWIR detectors has been completed, whilst the H4RGs and long wavelength detectors are still in progress. A custom cryogenic facility for infrared array testing (FIAT) has been designed and developed at European Southern Observatory (ESO) over the last few years in order to characterize the infrared detectors for ELT and future Very Large Telescope instruments. FIAT is currently being commissioned in our labs with an H4RG engineering detector. FIAT will be used to characterize the science H4RG‐15 detectors for MICADO and HARMONI, the two first‐light instruments of the ELT while the existing Mosaic Test Facility (MTF) will be used for characterizing the SWIR detectors for METIS. This paper presents an overview of the detector systems for the three instruments, their engineering challenges, and the requirements for the detectors' performance and their characterization program. The paper will also describe a test setup for H4RG detectors including a new preamplifier design with options to operate the detector in different modes and it will also report on the test results from the engineering H4RG detector, as part of the commissioning of FIAT and discuss detector performance and related detector issues.

Output buffer glow and its mitigation in H4RG-15 detectors

“…The PMOS buffers close to the fast shift register glow every time the array is read out. [6][7][8] The glow is a broadband optical signal that is detected at the bottom of the array and affects a few hundred rows. Figure 4 shows the output buffer glow at the bottom (close to the wire-bond edge) of the array in a 300 s dark bitmap with 100 UTR samples.…”