Quantum efficiency test set up performances for NIR detector characterization at ESTEC

Abstract

The Payload Technology Validation Section (Future mission preparation Office) at ESTEC is in charge of specific mission oriented validation activities, for science and robotic exploration missions, aiming at reducing development risks in the implementation phase. These activities take place during the early mission phases or during the implementation itself. In this framework, a test set up to characterize the quantum efficiency of near infrared detectors has been developed.The first detector to be tested will an HAWAII-2RG detector with a 2.5um cut off, it will be used as commissioning device in preparation to the tests of prototypes European detectors developed under ESA funding. The capability to compare on the same setup detectors from different manufacturers will be a unique asset for the future mission preparation office. This publication presents the performances of the quantum efficiency test bench to prepare measurements on the HAWAII-2RG detector. A SOFRADIR Saturn detector has been used as a preliminary test vehicle for the bench. A test set up with a lamp, chopper, monochromator, pinhole and off axis mirrors allows to create a spot of 1mm diameter between 700nm and 2.5um.The shape of the beam has been measured to match the rms voltage read by the Merlin Lock -in amplifier and the amplitude of the incoming signal. The reference detectors have been inter-calibrated with an uncertainty up to 3 %. For the measurement with HAWAII-2RG detector, the existing cryostat [1] has been modified to adapt cold black baffling, a cold filter wheel and a sapphire window. An statistic uncertainty of ±2.6% on the quantum efficiency on the detector under test measurement is expected.

Facility for the radiometric characterization of space-based visible-near infrared detectors

“…1.2 specifies the use of a double-monochromator to extract the required wavelength. Typically, when using a single-monochromator, additional filters shall be implemented to improve the purity of the signal, as is the case for Hill et al, 27 Crouzet et al, 18 and Coles et al 23 The advantage of using a double-monochromator is to provide a tunable monochromatic flux with a high level of straylight rejection at the output selection; the undesirable high orders of diffraction are removed thanks to the internal filter wheel equipped with high-pass filters. Typically, the wavelength scale accuracy increases from AE0.2 to AE0.1 nm, when compared against a single-monochromator, and the wavelength reproducibility also increases from AE0.05 to AE0.025 nm.…”

“…Similar to the BIRA-IASB facility, Cosentino et al 26 . use different ND filters to provide adjustable radiance, whereas facilities, such as Crouzet et al., 18 prefer the use of apertures to vary the intensity of the flux. Another example is the case of Hill et al 27 .…”

“…The stability of the lamp is continuously monitored and reported to be in the order of 1%. 18,19 However, the power is not usually higher than 500 W, 20,21 and some considerations must be taken into account to provide enough flux to the detector, especially when the system requires the use of an IS or a diffuser. Other light sources used include 3000 K blackbodies 14,19 and LED illumination sources.…”

“…What is typical among these testing facilities is the use of quartz-tungsten-halogen (QTH) and xenon lamps as their main light source. The stability of the lamp is continuously monitored and reported to be in the order of 1% 18 , 19 . However, the power is not usually higher than 500 W, 20 , 21 and some considerations must be taken into account to provide enough flux to the detector, especially when the system requires the use of an IS or a diffuser.…”

“…ISs are the general solution to provide a uniform light beam to the detector, especially when measuring QE. However, depending on its properties, some additional items could be added to achieve the desired homogeneity (usually 1% 18 ). For instance, when the IS is too small and the image of the aperture is still visible at the output port, adding flat diffusers could improve the uniformity of the beam 22 regardless attenuation.…”