Infrared Search and Track systems are an essential element of the modern and future combat aircrafts. Passive automatic
search, detection and tracking functions, are key points for silent operations or jammed tactical scenarios.
SKYWARD represents the latest evolution of IRST technology in which high quality electro-optical components,
advanced algorithms, efficient hardware and software solutions are harmonically integrated to provide high-end
affordable performances. Additionally, the reduction of critical opto-mechanical elements optimises weight and volume
and increases the overall reliability.
Multiple operative modes dedicated to different situations are available; many options can be selected among multiple or
single target tracking, for surveillance or engagement, and imaging, for landing or navigation aid, assuring the maximum
The high quality 2D-IR sensor is exploited by multiple parallel processing chains, based on linear and non-linear
techniques, to extract the possible targets from background, in different conditions, with false alarm rate control.
A widely tested track processor manages a large amount of candidate targets simultaneously and allows discriminating
real targets from noise whilst operating with low target to background contrasts.
The capability of providing reliable passive range estimation is an additional qualifying element of the system.
Particular care has been dedicated to the detector non-uniformities, a possible limiting factor for distant targets detection,
as well as to the design of the electro-optics for a harsh airborne environment.
The system can be configured for LWIR or MWIR waveband according to the customer operational requirements. An
embedded data recorder saves all the necessary images and data for mission debriefing, particularly useful during inflight
system integration and tuning.
Cooled infrared detectors are typically characterized by well-known electro-optical parameters: responsivity, noise equivalent temperature difference, shot noise, 1/f noise, and so on. Particularly important for staring arrays is also the residual fixed pattern noise (FPN) that can be obtained after the application of the nonuniformity correction (NUC) algorithm. A direct measure of this parameter is usually hard to define because the residual FPN strongly depends, other than on the detector, on the choice of the NUC algorithm and the operative scenario. We introduce three measurable parameters: instability, nonlinearity, and a residual after a polynomial fitting of the detector response curve, and we demonstrate how they are related to the residual FPN after the application of an NUC (the relationship with three common correction algorithms is discussed). A comparison with experimental data is also presented and discussed.
Due to the fast-growing of cooled detector sensitivity in the last years, on the image 10-20 mK temperature difference between adjacent objects can theoretically be discerned if the calibration algorithm (NUC) is capable to take into account and compensate every spatial noise source. To predict how the NUC algorithm is strong in all working condition, the modeling of the flux impinging on the detector becomes a challenge to control and improve the quality of a properly calibrated image in all scene/ambient conditions including every source of spurious signal. In literature there are just available papers dealing with NU caused by pixel-to-pixel differences of detector parameters and by the difference between the reflection of the detector cold part and the housing at the operative temperature. These models don’t explain the effects on the NUC results due to vignetting, dynamic sources out and inside the FOV, reflected contributions from hot spots inside the housing (for example thermal reference far of the optical path). We propose a mathematical model in which: 1) detector and system (opto-mechanical configuration and scene) are considered separated and represented by two independent transfer functions 2) on every pixel of the array the amount of photonic signal coming from different spurious sources are considered to evaluate the effect on residual spatial noise due to dynamic operative conditions. This article also contains simulation results showing how this model can be used to predict the amount of spatial noise.
The raw output of a generic infrared vision system, based on staring arrays, is spatially not uniform. This spatial noise
can be much greater than the system NETD, and determines a strong drop in system performance.
Therefore we need to model all system non-uniformity (NU) sources to highlight the parameters that should be
controlled by optical and mechanical design, the ones depending on the focal plane array and those that can be corrected
In this paper, we identify the main NU sources (optical relative irradiance, housing straylight, detector pixel-pixel
differences and non linearity), we show how to model these sources and how they are related to the design and physical
parameters of the system. We then describe the total signal due to these sources at the detector output. Applying different
NUC algorithms to this signal, the final results on the image can be simulated finding a proper correction algorithm. At
the end we show the agreement between the model with the experimental data taken on a real system.
Changing a limited set of parameters, this model can be applied to many third generation thermal imager configurations.
In the framework of a modernization program, supported by Italian Army, Galileo Avionica (a Finmeccanica company)
has developed a family of small equipments based on suites of electro-optics sensors. These modules, designed and built
by GA, range from uncooled V0x 25 micron thermal imagers, small and very compact laser rangefinders, CMOS
Visible sensors to the last generation of colour OLED microdisplay based visual units. All the EO assemblies are
integrated to form very small and lightweight Integrated Sight, a Multi Function Target Locator, and Dynamic Aiming
System. Even if the equipments have been developed for military applications many other applications such as law
enforcements or surveillance can be envisaged.
The definition and preliminary design of a thermal imager for earth observation applications has been performed, justified by a thorough analysis of user requirements. A survey of international programmes and other sources have been used to derive the radiometric requirements at ground level. Then instrument requirements at top of atmosphere have been obtained by means of the usual split-window techniques for land and sea. Preliminary instrument radiometric performances have been estimated on the basis of a review of possible instrument concepts (detectors and scan modes). A trade-off analysis between instrument requirements and performances led to the identification of two classes of instruments - the first based on high performance, cooled infrared detectors, and the second relying on microbolometer technology, with lower performance but not constrained by the need for a cryocooler. The applications feasible by means of each of them have been identified. The chosen instrument baseline was that using uncooled microbolometers, for which the best spatial and radiometric resolution achievable has been assessed, in order to cover as many applications as possible in view of the analysis of requirements. The selected baseline has been further detailed, up to a complete outline of the instrument, in order to confirm the achievable performance and assure its feasibility.
The in-flight radiometric calibration of satellite multispectral sensor for earth and atmospheric observations can be conveniently based on solar diffusers. Theoretically, a knowledge of the spectral bi-directional scatter distribution function (BSDF) of the diffuser panel, and the solar incidence angle is all that is needed to allow the retrieval of the earth albedo in the observed direction. At the request of the ESA, the Centre Spatial de Liege, with the support of Officine Galileo as subcontractor, is currently designing a high-versatility high-accuracy BSDF measurement set-up with application to the calibration of space solar diffusers. This instrument will allow a BSDF measurements uncertainty within 1 percent for any angle in the wavelength range from 200 nm to 2400 nm. Vacuum measurements, polarization analysis capabilities and thermalization of the test sample between 200K and 300K are other unique features of this set-up.