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Long wavelength type-II superlattice barrier infrared detector for CubeSat hyperspectral thermal imager

Rafol Sir B., Gunapala Sarath D., Ting David Z., Soibel Alexander, Khoshakhlagh Arezou, Keo Sam A., Pepper Brian J., Hill Cory J., Maruyama Yuki, Fisher Anita M., Sood Ashok, Zeller John, Wright Robert, Lucey Paul, Nunes Miguel, Flynn Luke, Babu Sachidananda, Ghuman Parminder

Opto-Electronics Review

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2023

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Vol. 31, Special Issue

art. no. e144569

EN

The hyperspectral thermal imaging instrument for technology demonstration funded by NASA’s Earth Science Technology Office under the In-Space Validation of Earth Science Technologies program requires focal plane array with reasonably good performance at a low cost. The instrument is designed to fit in a 6U CubeSat platform for a low-Earth orbit. It will collect data on hydrological parameters and Earth surface temperature for agricultural remote sensing. The long wavelength infrared type-II strain layer superlattices barrier infrared detector focal plane array is chosen for this mission. With the driving requirement dictated by the power consumption of the cryocooler and signal-noise-ratio, cut-off wavelengths and dark current are utilized to model instrument operating temperature. Many focal plane arrays are fabricated and characterised, and the best performing focal plane array that fulfils the requirements is selected. The spectral band, dark current and 8-9.4 μm pass band quantum efficiency of the candidate focal plane array are: 8-10.7 μm, 2.1∙10ˉ⁵ A/cm², and 47%, respectively. The corresponding noise equivalent difference temperature and operability are 30 mK and 99.7%, respectively. Anti-reflective coating is deposited on the focal plane array surface to enhance the quantum efficiency and to reduce the interference pattern due to an absorption layer parallel surfaces cladding material.

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Discussion around IR material and structure issues to go toward high performance small pixel pitch IR HOT FPAs

Gravrand Olivier, Baier Nicolas, Ferron Alexandre, Rochette Florent, Lobre Clément, Bertoz Jocelyn, Rubaldo Laurent

Opto-Electronics Review

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2023

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Vol. 31, Special Issue

art. no. e144561

EN

In the last decade, infrared imaging detectors trend has gone for smaller pixels and larger formats. Most of the time, this scaling is carried out at a given total sensitive area for a single focal plane array. As an example, QVGA 30 μm pitch and VGA 15 μm pitch exhibit exactly the same sensitive area. SXGA 10 μm pitch tends to be very similar, as well. This increase in format is beneficial to image resolution. However, this scaling to even smaller pixels raises questions because the pixel size becomes similar to the IR wavelength, but also to the typical transport dimensions in the absorbing material. Hence, maintaining resolution for such small pixel pitches requires a good control of the modulation transfer function and quantum efficiency of the array, while reducing the pixel size. This might not be obtained just by scaling the pixel dimensions. As an example, bulk planar structures suffer from excessive lateral diffusion length inducing pixel-to-pixel cross talk and thus degrading the modulation transfer function. Transport anisotropy in some type II superlattice structures might also be an issue for the diffusion modulation transfer function. On the other side, mesa structures might minimize cross talk by physically separating pixels, but also tend to degrade the quantum efficiency due to a non-negligible pixel fill factor shrinking down the pixel size. This paper discusses those issues, taking into account different material systems and structures, in the perspective of the expected future pixel pitch infrared focal plane arrays.

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Acceleration algorithm for constant-statistics method applied to the nonuniformity correction of infrared sequences

Jara-Chavez A. G., Torres-Vicencio F. O.

Opto-Electronics Review

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2015

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Vol. 23, No. 1

116-119

EN

Non-uniformity noise, it was, it is, and it will probably be one of the most non-desired attached companion of the infrared focal plane array (IRFPA) data. We present a higher order filter where the key advantage is based in its capacity to estimates the detection parameters and thus to compensate it for fixed pattern noise, as an enhancement of Constant Statistics (CS) theory. This paper shows a technique to improve the convergence in accelerated way for CS (AACS: Acceleration Algorithm for Constant Statistics). The effectiveness of this method is demonstrated by using simulated infrared video sequences and several real infrared video sequences obtained using two infrared cameras.

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Teoretyczne aspekty zastosowania monolitycznego analizatora obrazu do obserwacji gwiazd w wyznaczeniach astronomicznych

Bobkiewicz P.

Prace Wydziału Nawigacyjnego Akademii Morskiej w Gdyni

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2008

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Z. 22

5-16

PL

W artykule opisano niektóre aspekty zastąpienia obserwacji wzrokowych w wyznaczeniach astronomicznych obserwacją przy użyciu monolitycznego analizatora obrazu. Przedstawiono wpływ parametrów technicznych przykładowego analizatora zastosowanego w teodolicie elektronicznym na dokładność wartości wchodzących do redukcji, przy czym do niezbędnego minimum ograniczono informacje o analizatorach obrazu. Zasadniczą treść pracy stanowi opis modelu matematycznego przejścia z danych uzyskanych w wyniku obróbki obrazu na dane do redukcji oraz opis metody kalibracji analizatora w teodolicie. Wykorzystanie analizatora obrazu pozwala na automatyczną obserwację przejść gwiazd w polu widzenia optycznych urządzeń geodezyjnych. Zarejestrowany obraz zostaje poddany komputerowej obróbce z uwzględnieniem kierunku osi celowej urządzenia, w wyniku czego określa się równanie ruchu ciała w układzie horyzontalnym. Zaproponowany sposób automatyzacji obserwacji można zrealizować dzięki rozwojowi technologii układów optoelektronicznych i komputerów. Szczególne znaczenie w tym zastosowaniu mają małe wymiary i niski poziom szumów monolitycznych analizatorów obrazu oraz bardzo dobra dostępność komputerów o dużej mocy obliczeniowej, niezbędnej do obróbki obrazu.

EN

The article is describing some aspects of replacing visual observation in geodetic astronomical measurements with observation with help of the focal plane array. Some essential information about focal plane array are announced. The mathematical model of converting from data get as a result of processing of the image to data for reduction formulas is presented. Also the method of the calibration of the theodolite with focal plane array is described. An influence of technical parameters of the focal plane array applied in the theodolite on the accuracy of the measurements is analyzed.

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InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

Rehm R., Walther M., Schmitz J., Fleißner J., Fuchs F., Ziegler J., Cabanski W.

Opto-Electronics Review

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2006

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Vol. 14, No. 1

19-24

EN

The first fully operational mid-IR (3–5 um) 256x256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detector chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement.

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High-performance IR detectors at SCD present and future

Nesher O., Klipstein P. C.

Opto-Electronics Review

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2006

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Vol. 14, No. 1

61-70

EN

For over 27 years, SCD has been manufacturing and developing a wide range of high performance infrared detectors, designed to operate in either the mid-wave (MWIR) or the long-wave (LWIR) atmospheric windows. These detectors have been integrated successfully into many different types of system including missile seekers, time delay integration scanning systems, hand-held cameras, missile warning systems and many others. SCD's technology for the MWIR wavelength range is based on its well established 2D arrays of InSb photodiodes. The arrays are flip-chip bonded to SCD's analogue or digital signal processors, all of which have been designed in-house. The 2D focal plane array (FPA) detectors have a format of 320×256 elements for a 30-µm pitch and 480×384 or 640×512 elements for a 20-µm pitch. Typical operating temperatures are around 77–85 K. Five years ago SCD began to develop a new generation of MWIR detectors based on the epitaxial growth of antimonide based compound semiconductors (ABCS). This ABCS technology allows band-gap engineering of the detection material which enables higher operating temperatures and multi-spectral detection. This year SCD presented its first prototype FPA from this program, an InAlSb based detector operating at a temperature of 100 K. By the end of this year SCD will introduce the first prototype MWIR detector with a 640×512 element format and a pitch of 15 µm. For the LWIR wavelength range SCD manufactures both linear Hg1–xCdxTe (MCT) detectors with a line of 250 elements and time delay and integration (TDI) detectors with formats of 288×4 and 480×6. Recently, SCD has demonstrated its first prototype uncooled detector which is based on VOx technology and which has a format of 384×288 elements, a pitch of 25 µm, and a typical NETD of 50 mK at F/1. In this paper, we describe the present technologies and products of SCD and the future evolution of our detectors for the MWIR and LWIR detection.