Natural and man-made obscurants like fog, cloud, smoke and dust are an impediment to the conduct of military operations, preventing effective pilotage, denying the ability to carry out surveillance and reconnaissance, and restricting situational awareness. Additionally, there is a growing interest in the ability to penetrate haze and fog for the safe navigation of autonomous vehicle applications.
There are several electro-optic technologies that offer improved ability to image through obscurants [1,2]. In this study the authors assessed 4 different active imaging technologies in the presence of an artificial smoke, and obtained 3D imagery of targets at ranges of 100m out to 1400m. The four systems tested were:
• a scanned time-correlated single photon counting (TCSPC) sensor using a InGaAs/InP single-photon avalanche diode (SPAD) detector operating at ~ 1.55 µm ;
• a 32 32 InGaAs/InP SPAD array using TCSPC at ~ 1.55 µm;
• a coherent frequency modulated continuous wave (FMCW) scanned lidar system ~ 1.55 µm , ;
• a CMOS SPAD array camera operating as a time gated imager operating at ~ 670nm.
The selection of sensors enables comparisons to be drawn between scanning and staring systems and direct detection and coherent detection, and between short-wave infrared and visible wavelengths.
Three-dimensional structured targets were placed at ranges of 100 – 150m and smoke was introduced between the targets and the sensors. The smoke transmission was measured with a separate laser device to correlate the imagery with the level of attenuation presented by the smoke and thereby relate the image quality to the degree of optical loss in the system. For the coherent lidar system, long range 3D images were obtained out to a distance of 1400m, and imaging through smoke of a target at 900m was achieved. Under the test conditions at least 2 of the systems have demonstrated the ability to obtain images through greater than 4 attenuation lengths of obscurant between transceiver and target, and work is progressing on image processing approaches to reconstruct images at greater levels of loss.
Imagery from the systems will be presented, the relative merits of the different techniques discussed, and the prospects for future practical systems will be explored.
 “Demonstration of frequency modulated continuous wave (FMCW) eye-safe, coherent LIDAR to See Through Clouds”, M.Silver, P.Feneyrou, L.Leviander, A.Martin and J Parsons, Optro, Jan 2018.
 “Depth imaging through obscurants using time-correlated single-photon counting”, R.Tobin, A.Halimi, A.McCarthy, M.Laurenzis, F.Christnacher and G.S.Buller, SPIE Vol 10659, April 2018
Supplying thermal imagers for today's operational needs requires flexibility, responsiveness and ever reducing costs. This paper will use the latest thermal imager development in the Catherine range from Thales UK to address the technical interactions with such issues as modularity, re-use, regions of deployment and supply chain management. All this is in the context of the increasingly public operations and the pressures on validating performance especially when weapon aiming is involved.
The phenomenon of polarisation causes smooth man-made objects, such as metal and glass, to have a different polarisation signature to that of natural vegetation. Therefore, polarisation has the potential to discriminate man-made objects from background clutter. Polarimetric information, combined with conventional thermal imaging, provides a powerful means of reducing false alarms in applications such as situational awareness, detection of low signature targets and disturbed earth. The paper presents results of discriminative imaging algorithms that were designed to augment polarimetric signatures. Recent results from a LWIR polarimetric imager are presented and these show the merit of discriminative imaging techniques when applied to polarimetric thermal imagers.
Since 2005, the THALES Group has successfully manufactured TV/4 format QWIP sensitive arrays in high rate
production at the THALES Research and Technology Laboratory. The full-TV array manufacturing started in 2007.
Uniformity and stability were the key parameters which led to the selection of this technology for thermal cameras.
Another widely claimed advantage for QWIPs was the versatility of the band-gap engineering and of the III-V
processing allowing the custom design of quantum structures to fulfill the requirements of specific applications such as:
very long wavelength (VLWIR); multi-spectral detection; and polarimetric detection.
Serial production of CATHERINE-XP and CATHERINE-MP has now started for the various programs for which both
cameras have been selected. A review of the QWIP Production status, CATHERINE achievements and current programs
are presented. THALES has based its current strategy on very compact TI in order to address the largest range of
platforms and applications, and is working in cooperation with Sofradir and TRT / III-Vlab on the evolution of the
product to take advantage of the new capabilities offered by QWIP technology. In addition, future products based on
dual band, multi-band and polarimetric imagery are under development. An overview of these developments is presented.
The first generation of high performance thermal imaging sensors in the UK was based on two axis opto-mechanical
scanning systems and small (4-16 element) arrays of the SPRITE detector, developed during the 1970s. Almost two
decades later, a 2nd Generation system, STAIRS C was introduced, based on single axis scanning and a long linear
array of approximately 3000 elements. The UK has now begun the industrialisation of 3<sup>rd</sup> Generation High Performance
Thermal Imaging under a programme known as "Albion". Three new high performance cadmium mercury telluride
arrays are being manufactured. The CMT material is grown by MOVPE on low cost substrates and bump bonded to the
silicon read out circuit (ROIC). To maintain low production costs, all three detectors are designed to fit with existing
standard Integrated Detector Cooling Assemblies (IDCAs). The two largest focal planes are conventional devices
operating in the MWIR and LWIR spectral bands. A smaller format LWIR device is also described which has a smart
ROIC, enabling much longer stare times than are feasible with conventional pixel circuits, thus achieving very high
sensitivity. A new reference surface technology for thermal imaging sensors is described, based on Negative
Luminescence (NL), which offers several advantages over conventional peltier references, improving the quality of the
Non-Uniformity Correction (NUC) algorithms.
The first generation of high performance thermal imaging sensors in the UK was based on two axis opto-mechanical scanning systems and small (4-16 element) arrays of the SPRITE detector, developed during the 1970s. Almost two decades later, a 2nd Generation system, STAIRS C was introduced, based on single axis scanning and a long linear array of approximately 3000 elements. This paper addresses the development of the UK's 3rd Generation High Performance Thermal Imaging sensor systems, under a programme known as "Albion". Three new high performance detectors, manufactured in cadmium mercury telluride, operating in both MWIR and LWIR, providing high resolution and sensitivities without need for opto-mechanical scanning systems will be described. The CMT material is grown by MOVPE on low cost substrates and bump bonded to the silicon read out circuit (ROIC). All three detectors are designed to fit with existing standard Integrated Detector Cooling Assemblies (IDCAs). The two largest detectors will be integrated with field demonstrator cameras providing MWIR and LWIR solutions that can rapidly be tailored to specific military requirements. The remaining detector will be a LWIR device with a smart ROIC, facilitating integration times much longer than can typically be achieved with focal plane arrays and consequently yield very high thermal sensitivity. This device will be demonstrated in a lab based camera system.
THALES have developed for volume manufacture two high performance low cost thermal imaging cameras based on the THALES Research & Technology (TRT) 3<sup>rd</sup> generation gallium arsenide long wave Quantum Well Infrared Photodetector (QWIP) array. Catherine XP provides 768 x 575 CCIR video resolution and Catherine MP provides 1280 x 1024 SXGA video resolution. These compact and rugged cameras provide 24-hour passive observation, detection, recognition, and identification in the 8 to 12μm range, providing resistance to battlefield obscurants and solar dazzle, and are fully self-contained with standard power and communication interfaces. The cameras have expansion capabilities to extend functionality (for example automatic target detection) and have network battlefield capability. Both cameras benefit from the high quantum efficiency and freedom from low frequency noise of the TRT QWIP, allowing operation at 75 K, low integration times and non-interruptive non-uniformity correction. The cameras have successfully reached
technology readiness level 6/7 and have commenced environmental qualification testing in order to complete the development programmes. These latest additions to the THALES Catherine family provide high performance thermal imaging at an affordable cost.