As far as calibrated radiometric imaging is concerned, a complete prediction of oblique incidence effect on the FPA pixels’ response is required. Since a light coupling scheme needs to be used in QWIP detectors, this effect is particularly complicated to understand. This article presents two complementary test benches which allow to quantify the effect of oblique incidence on cooled infrared detectors issued from different technologies. The first test bench performs measurements over a wide angular range with low background emission levels, but gives spectrally integrated measurements. The second one delivers spectrally resolved responses for incident angles lower than 30°. In order to validate both experimental concepts, we studied QWIPs equipped with 2D periodic gratings. Relatively large pixels (100x100μm2) were chosen to ease comparison with models. Calculations based on the modal expansion method reveal that diffraction off an infinite grating does not account very well for the observed spectral responses.
An infrared spectroradiometer is being developed at the ONERA to make field measurements of radiance and emissivity of terrestrial surface materials (MISTERE). The instrument, entirely cooled, is a stationary Fourier spectrometer. The principle of measurement based on the sampling of a canted interferogram by a 2D array of detectors will be detailed and the expected performances in terms of resolution, free spectral range, signal-to-noise ratio and scan rate will be presented.
For some years, the IR laboratory of ONERA (France) carried out accurate electro-optical characterization on IR detectors. This paper presents some works about IR detector radiation hardness measurements: ONERA, in collaboration with DGA/CEG, measured the effects of gamma radiation on high wavelength IRCMOS. The test conditions respect hard constraints, particularly, during the radiation, detectors were cooled and operating. This paper reviews the implementation of these tests in very hard environment electromagnetic field, radiation, noise ...) and of a test protocol. In spite of severe environmental conditions, quality of measurement is comparable with those done in the laboratory. General component behaviors, transionnal and permanent effects, are summed up for very high dose rate.
The article deals with infrared detector Si:Ga made by CENG/LETI/LIR. This extrinsic photoconductor is hybridized to a direct voltage silicon NMOS readout circuit (DVR) and works at a temperature closed to 10 K. For some years, ONERA (Office National d'Etudes et Recherches Aerospatiales) has been studying the Si:Ga by testing 32 X 32, 64 X 64 and 128 X 192 focal plane arrays. Several measurements have been done, and permit a good comprehension of the general architecture and behavior of the component, and so the realization of driving and acquisition electronic boards. Other tests have been realized, and the points of interest which will be discussed in this article are the study of the fixed pattern noise and the temporal evolution of the performances of the nonuniformity correction. Indeed, pixel nonuniformity and nonlinearity degrade array performances. Although algorithms (two points correction) have been developed to decrease this fixed pattern noise, the temporal stability of the correction has been analyzed to show if the time since the last calibration reduces its performance. So, all this knowledge about Si:Ga leads to the integration of a 128 X 192 focal plane array (FPA) in CRYSTAL (CRYogenic System for Thermographic analysis of Aerodynamic Layer) camera for ETW (European Transonic Windtunnel).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.