The development of a new thermal imaging camera, for long range surveillance applications, is described together with the enabling technology. Previous publications have described the development of large arrays of 12μm pixels using Metal Organic Vapour Phase Epitaxy (MOVPE) grown Mercury Cadmium Telluride (MCT) for wide area surveillance applications. This technology has been leveraged to produce the low cost 1280×720 pixel Medium Wave IR focal plane array at the core of the new camera. Also described is the newly developed, high performance, ×12 continuous zoom lens which, together with the detector, achieves an Instantaneous Field of View (IFOV) of 12.5μrad/pixel enabling long detection, recognition and identification ranges. Novel image processing features, including the turbulence mitigation algorithms deployed in the camera processing electronics, are also addressed. Resultant imagery and performance will be presented.
A highly ruggedized infra-red sensor module has been developed which is suitable for a variety of fast framing
applications in hostile fire detection and in scientific or industrial metrology. The sensor offers <1000fps in the full
384x384 format and useful images up to 6500fps in smaller formats. High operability for either mid-wave or long-wave
IR applications is assured with high performance MOVPE fabrication technology. The paper reports design concepts
and performance data for the MW variant.
The Osprey-E sensor module consists of an integrated detector-cooler assembly (IDCA) and custom proximity
electronics mounted in a lightweight, ruggedized housing. Based on the half-TV format Osprey FPA, it implements
recent improvement in SELEX Galileo's array hybridization technique. Ongoing tests have shown that performance is
not significantly degraded after more than 5000 cooldown cycles. The FPA exploits SELEX Galileo's High Operating
Temperature (HOT) HgCdTe (MCT) and is optimized for operation at 110K. Very low levels of defective pixels
(<0.003%) have been achieved at this temperature. The proximity electronics are a new design that originates from
SELEX Galileo's Centre of Excellence in Infrared Detectors. The electronics provide all the necessary supplies and
signals for detector operation and digitize the detector output into 14-bit digital video. The sensor has been developed to
offer a very lightweight, rugged camera core particularly suited to airborne applications.
SELEX Galileo has developed avalanche photodiode technology in HgCdTe to serve a whole range of applications in
defence, security, commercial and space research. Burst-illumination LIDAR (BIL), using a near-infrared pulse laser and
a fast, gated detector, is now adopted for most long range imaging applications. New results from range trials using
prototype systems based on multifunctional and 3D detectors are reported. In the astronomy field, APD arrays at 2.5 μm
cutoff can provide near-single photon sensitivity for future wavefront sensors and interferometric applications. Under a
contract from European Southern Observatories arrays have been successfully demonstrated with gains up to 20× and
negligible dark current at 77K. Under a European Space Agency contract, a large area, single element detector has been
designed for the 2.015μm CO<sub>2</sub> absorption line. The sensor is specifically designed to be operated at 200K so that
thermoelectric cooling is viable. The element is made up of many sub-pixel diodes each deselectable to ensure high
breakdown in the macro-pixel. The latest results of the detector and its associated transimpedance amplifier (TIA) are
There is considerable interest in sensors which are optimised for detecting infrared radiation outside the normal thermal
bands (3-12μm). This paper presents the development of photodiode arrays in Hg<sub>1-x</sub>Cd<sub>x</sub>Te (MCT) that are sensitive in the
very long wave (VLW) band to 14μm or in the visible and SWIR band below 2.5μm wavelength.
The VLW arrays are heterostructure diodes fabricated from MCT grown by Metal Organic Vapour Phase Epitaxy
(MOVPE). These are staring, focal plane arrays of mesa-diodes bump bonded to silicon read-out circuits. Measurements
are presented demonstrating state-of-the-art performance over the temperature range 55-80K, for detectors with a cut-off
wavelength of up to 14μm (at 77K).
The SWIR/Visible detectors consist of an array of loophole photodiodes fabricated using MCT grown by Liquid Phase
Epitaxy (LPE). The technology is suited to imaging LIDAR, NIR/Visible imaging, spectroscopy or hyperspectral
applications. The diodes operate as avalanche photodiodes (APDs) which provides near-ideal gain in the pixel.
Measurements are presented demonstrating state-of-the-art performance in the range 80K-200K from arrays with a cut-off
Supporting technologies are also discussed. Silicon circuitry must be implemented in the SWIR and VLW bands that is
appropriate to avalanche operation or copes with the low photon flux or low photodiode impedance. Trade-offs between
conventional direct injection (DI), buffered direct injection (BDI), pixel capacitive transimpedance amplifier (CTIA) and
source-follower per detector (SFPD) are presented. Work is in progress to increase the MOVPE wafer size to 6" which
will enable large area arrays to be produced in the SW, MW, LW and VLW bands.
SELEX S&AS is developing a family of infrared sensors for earth observation missions. The spectral bands cover shortwave
infrared (SWIR) channels from around 1μm to long-wave infrared (LWIR) channels up to 15μm.
Our mercury cadmium telluride (MCT) technology has enabled a sensor array design that can satisfy the requirements of
all of the SWIR and medium-wave infrared (MWIR) bands with near-identical arrays. This is made possible by the
combination of a set of existing technologies that together enable a high degree of flexibility in the pixel geometry,
sensitivity, and photocurrent integration capacity.
The solution employs a photodiode array under the control of a readout integrated circuit (ROIC). The ROIC allows
flexible geometries and in-pixel redundancy to maximise operability and reliability, by combining the photocurrent from
a number of photodiodes into a single pixel. Defective or inoperable diodes (or "sub-pixels") can be deselected with
tolerable impact on the overall pixel performance.
The arrays will be fabricated using the "loophole" process in MCT grown by liquid-phase epitaxy (LPE). These arrays
are inherently robust, offer high quantum efficiencies and have been used in previous space programs. The use of
loophole arrays also offers access to SELEX's avalanche photodiode (APD) technology, allowing low-noise, highly
uniform gain at the pixel level where photon flux is very low.