Unveiling Hidden Targets: How Advanced Thermal Imaging Technologies Conquer Darkness, Fog, and Smoke

Rajesh Uppal March 9, 2024 Industry, Photonics Comments Off on Unveiling Hidden Targets: How Advanced Thermal Imaging Technologies Conquer Darkness, Fog, and Smoke 1,272 Views

In a world predominantly reliant on vision, we are often limited by our ability to see in adverse conditions. In the absence of daylight, in dense fog, or within a veil of smoke, our vision is compromised. In a world where visibility is essential for safety and security, the limitations of human vision can be a significant obstacle. Whether you’re in the military, law enforcement, or even just interested in outdoor activities, the ability to see clearly in the darkest of nights, dense fog, or thick smoke can be a game-changer.

But what if there was a way to transcend these barriers and see what’s hidden from our eyes? This is where advanced thermal imaging technology takes center stage, enabling us to unveil concealed targets in conditions where conventional vision falls short. In this article, we delve into the remarkable world of thermal imaging and how it conquers darkness, fog, and smoke to reveal what lies beneath.

The Power of Thermal Imaging

Thermal imaging cameras, sometimes referred to as infrared cameras, work by detecting and visualizing heat, not visible light. They operate within the infrared spectrum, which encompasses wavelengths longer than those of visible light. Here’s how they do it:

1. Detecting Infrared Radiation: All objects warmer than absolute zero (-273°C/-459°F) emit infrared radiation. This radiation in the MWIR and LWIR wavelengths (3µm–14µm) is emitted in an amount proportional to the temperature of the object. Thermal imaging focuses and detects this radiation, then translates the temperature variations into a greyscale image, using brighter and darker shades of grey to represent hotter and cooler temperatures, which gives a visual representation to the heat profile of the scene.

2. Translating Heat into Images: These cameras focus on and detect the emitted infrared radiation, capturing even the slightest variations in heat, as small as 0.01° Celsius. This data is then translated into a greyscale image, with brighter and darker shades representing hotter and cooler temperatures, creating a visual representation of the heat profile in the scene.

3. Overcoming the Invisibility of Infrared: Although infrared energy is invisible to the human eye, thermal imaging technologies can convert this energy into visible colors. The camera processes this information, and the output is a standard video signal that can be viewed on a regular monitor.

IR Spectrum

Infrared (IR) radiation constitutes a segment of the electromagnetic spectrum extending beyond visible light. This spectrum can be divided into several categories based on wavelength, each possessing unique characteristics and applications. These categories include near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR).

Near-Infrared (NIR) is characterized by wavelengths ranging from about 0.75 to 1.4 micrometers (µm). It is often referred to as “short-wavelength” IR and bears similarities to visible light. NIR is extensively used in applications involving imaging, sensing, and communication, such as TV remote controls and agricultural monitoring.

Short-Wave Infrared (SWIR) spans from approximately 1.4 to 3.0 µm. Positioned between NIR and MWIR, SWIR is known as the “water absorption window” due to its resilience to water absorption. It is vital for applications like night vision, surveillance, and material analysis, especially in low-light conditions and through haze.

Mid-Wave Infrared (MWIR) ranges from about 3.0 to 5.0 µm. MWIR captures images in the thermal band and detects temperature differences, making it ideal for thermal imaging. It is widely used in military surveillance, search and rescue operations, and industrial monitoring.

Long-Wave Infrared (LWIR) covers wavelengths from around 8.0 to 14 µm and is often referred to as “thermal infrared.” Objects at or near room temperature emit LWIR radiation, and this range is crucial for thermal imaging. Applications include medical thermography, building inspections, heat leak detection in buildings, and military and industrial thermal imaging.

In summary, the IR spectrum’s division into NIR, SWIR, MWIR, and LWIR is based on wavelength, and each category serves distinct purposes. NIR and SWIR are used for imaging and remote sensing, while MWIR and LWIR are prominent in thermal imaging and temperature measurement. Understanding these IR categories is essential for selecting the appropriate technology for a wide array of applications.

Defeating Darkness

As a technology originally developed for military purposes, thermal imaging allows soldiers to effectively see in areas where little to no light is present, such as in the evening, or during incidents where smoke, fog, dust or any other airborne obscurant is present. These cameras allow soldiers to operate effectively in situations where little to no light is present, such as during nighttime operations or when smoke, fog, or dust obscures visibility. Key features include:

1. Wide-Angle Detection: Humans, animals, and vehicles typically have a higher temperature than their surroundings. This temperature contrast provides the advantage of detecting threats from a considerable distance, sometimes up to 50 kilometers, much farther than optical imaging allows.

2. Penetrating Obscurants: Thermal energy can pass through various visible obscurants, including smoke, dust, light fog, and light foliage. This means that thermal imaging remains reliable even in adverse environmental conditions.

3. Revealing Concealed Objects: Precise temperature differences detected by thermal imaging can sometimes expose objects hidden beneath other materials, such as revealing structural elements behind walls or detecting concealed items under clothing.

New applications for thermal imaging

The advancements in thermal imaging technologies have led to a number of new applications for thermal imaging. For example, thermal imaging cameras are now being used to:

Detect early signs of disease: Thermal imaging cameras can be used to detect early signs of disease, such as inflammation and infection. This is because diseased tissues often have a different temperature than healthy tissues.
Improve energy efficiency: Thermal imaging cameras can be used to identify areas of heat loss in buildings and industrial facilities. This information can then be used to improve energy efficiency and reduce costs.
Enhance safety and security: Thermal imaging cameras can be used to detect people and objects in low-light or no-light conditions. This can be used to improve safety and security in a variety of settings, such as construction sites, airports, and borders.

Future of thermal imaging

The future of thermal imaging is very promising. As the technology continues to advance, thermal imaging cameras will become even more sensitive, affordable, and portable. This will lead to new and innovative applications for thermal imaging in a wide range of industries.

Here are some of the potential future applications of thermal imaging:

Autonomous driving: Thermal imaging cameras could be used to help autonomous vehicles detect people and objects in low-light or no-light conditions. This could improve the safety and reliability of autonomous vehicles.
Precision agriculture: Thermal imaging cameras could be used to monitor crop health and identify areas of disease or stress. This could help farmers to improve their yields and reduce their use of pesticides.
Medical diagnosis: Thermal imaging cameras could be used to diagnose a wider range of diseases, such as cancer and heart disease. This could lead to earlier diagnosis and better treatment outcomes.

Military Applications

Thermal imaging plays a crucial role in various military applications. Whether scanning large areas from aircraft, guiding systems to prevent sea collisions, identifying, locating, and targeting enemy forces, or providing enhanced perimeter security, these technologies are indispensable.

Motion detection is an important element of Automatic Target Recognition (ATR) and perimeter monitoring systems. Thermal imaging has become an integral part of these systems because of its ability to operate in all weather conditions. Generally, for long range surveillance applications, the images containing the moving target are transmitted to the base station for manual interpretation. In short range surveillance, moving target identification (MTI) systems intelligently recognize if the moving target is a potential enemy target and transmits this information to a firing system.

Thermal imagers mounted on combat vehicles offer long-range surveillance, rapid identification, and threat location. In addition, early warning thermal imaging systems enable the military to assess potential threats and respond effectively, even before they materialize.

Technology Trends

A thermal imaging camera is a contactless device that detects infrared energy (heat emitted by objects) and converts it into a visual image. It consists of a lens, thermal sensor, a mechanical housing, and processing electronics. Some of the important characteristics of thermal imaging cameras are resolution, field of view, range, thermal sensitivity, focus, and spectral range.

As technology continually evolves, thermal imaging cameras are no exception. Some notable trends include:

1. Miniaturization: Advancements have led to the miniaturization of thermal imaging cores, making them lightweight and energy-efficient.

2. Improved Sensors: Developments aim to enhance the resolution, sensitivity, and pixel density of thermal sensors, resulting in higher-quality images. Smaller pixels, high-resolution capabilities, and faster frame rates are sought after for military applications.

3. Bi-Spectral Cameras: Cameras that integrate both thermal and visible light imaging capabilities offer enhanced target detection and tracking capabilities.

4. SWaP Optimization: Size, Weight, and Power (SWaP) optimization is a priority, with the goal of reducing the size and weight of thermal sensors without compromising performance. Thermal imaging cameras are becoming smaller and lighter. This makes them more portable and easier to use in field settings.

Reduced costs: The cost of thermal imaging cameras has fallen dramatically in recent years. This is due to a number of factors, including the development of new manufacturing techniques and the increasing availability of commercial components.

In the realm of thermal imaging, technological advancements have embarked on a quest for excellence. The pursuit of high-definition imaging is marked by the combination of a reduced pixel pitch and the evolution of readout circuit technology. An infrared sensor’s image quality is intricately tied to pixel count and spatial resolution.

As a reflection of this, a surge in the development of MWIR (Mid-Wave Infrared) cooled infrared sensors tailored for military use has become evident. The emphasis now lies in designing smaller pixels, often less than 10µm, within a larger format exceeding VGA resolution, and achieving higher operating temperatures above 150 Kelvin. This meticulous calibration aims to enhance performance while remaining aligned with the multifaceted demands of the defense sector, ranging from night vision to the integration of thermal imaging in binoculars, drones, and armored equipment. Such endeavors even find a home in futuristic concepts like the Infantry of the Future program, exemplified by innovations like shooting glasses equipped with infrared sensors

Artificial Intelligence: A Catalyst of Innovation

Artificial intelligence (AI) is becoming increasingly integrated into thermal imaging systems. AI algorithms can provide advanced analytics for intrusion detection and enhance overall scene understanding, helping soldiers make more informed decisions. In this dynamic landscape, algorithms and AI have proven to be instrumental in providing supplementary insights and added value, with their significance amplified within the military domain.

One notable trend is the seamless integration of AI and deep learning, specifically tailored for classification-based analytics, a development that has greatly enhanced intrusion detection. However, the realm of AI’s influence extends beyond mere detection. It empowers soldiers to comprehend the unfolding scene in a holistic manner. When a thermal image is subjected to the discerning filter of artificial intelligence, its capabilities expand to analyzing, adapting, evaluating alternative strategies, and crafting new approaches. This principle is becoming increasingly integral in the provisioning of state-of-the-art equipment for infantry, base camps, and military vehicles.

The confluence of improved processing power and the evolution of deep learning algorithms has ushered in a new era. This transformation equips Visual Content Analysis (VCA) systems with the ability to focus with pinpoint precision on relevant targets within a scene, be it individuals or vehicles. Simultaneously, it excels at filtering out inconsequential elements such as small animals or other scene disturbances, thus minimizing unnecessary alarms. In this synergy of thermal imaging and AI, we witness the birth of a more sophisticated, efficient, and perceptive defense ecosystem, setting new benchmarks in military innovation.

Leading the Way

Several companies are at the forefront of advancing thermal imaging technologies. ULIS, for instance, offers high-precision thermal image sensors with improved detection ranges and energy efficiency. BAE introduces sensors with smaller pixels that reduce lens size and optics costs while maintaining image quality.

Thermal Imaging Cameras

ULIS, the renowned French manufacturer of thermal image sensors for both commercial and military applications, has unveiled a groundbreaking advancement with the introduction of the Pico1024E GenII. This high-precision, energy-efficient megapixel thermal image sensor represents a significant leap in threat-detecting performance, boasting an expanded panoramic field of view and an extended detection range spanning from 3 to 5 kilometers. At the heart of this innovation lies the Pico1024E GenII’s remarkable features, including a 1024 x 768 resolution and a 17-micron pixel pitch. These attributes not only deliver extraordinary image quality but also excel in energy efficiency, consuming a mere 200mW of power. Most notably, this sensor exhibits exceptional thermal sensitivity, registering at less than 50mK—a 15 percent improvement over its predecessor. With a swift frame rate frequency of over 100Hz for rapid target tracking, this thermal image sensor empowers real-time situational awareness for helicopter pilots and land vehicle drivers in challenging conditions, such as low-light scenarios or dusty and smoky environments. Moreover, it augments operational capabilities, even enabling ‘man in the loop’ functionality for anti-surface missile systems. ULIS’ PICO E products have earned their place in various critical applications, including airborne local situation awareness in both European and North American contexts, as well as enhancing vision for drivers of land vehicles and contributing to European anti-surface missile programs. ULIS, a subsidiary of Sofradir and GE Equity, is renowned for its specialized design and manufacture of high-quality thermal image sensors catering to the diverse needs of commercial and military sectors.

On the other side of the English Channel, UK-based BAE has presented the TWV640 core, featuring a notable reduction in pixel size from 17 to 12 microns. This breakthrough enables imaging system manufacturers to cut lens dimensions by half and reduce optics costs by a substantial 20 percent, all without compromising image quality. What sets this sensor apart is its remarkable capability to capture images through adverse conditions such as fog, smoke, dust, and haze, all at a high frame rate of 60 Hz. Additionally, the TWV640 core demonstrates versatility by accommodating off-the-shelf lenses from typical optical component suppliers while adhering to standard interface protocols. This adaptability makes it suitable for a broad spectrum of applications, including day and night security cameras, firefighting vision systems, process monitoring, handheld targeting systems, automotive cameras, and thermography systems. BAE’s TWV640 core thus represents a significant advancement in thermal imaging technology with far-reaching implications for enhanced vision and surveillance across numerous domains.

Team Challenger 2 offers world-leading, thermal imaging technology for Challenger 2 tank upgrade

Developed by Leonardo in the UK, this technology is a pivotal component of Team Challenger 2’s proposal to upgrade the British Army’s Main Battle Tank. It harnesses the extraordinary capability of hundreds of thousands of individual pixels, each measuring a mere one-twelfth the thickness of a human hair, to detect temperature variances as subtle as one-fiftieth of a degree Celsius, resulting in exceptionally sharp imagery. With sighting being an indispensable aspect of a battle tank’s role, Leonardo’s sight system offers British troops unmatched 24-hour visibility, providing an advanced long-range threat identification system that maximizes the tank’s firepower. In collaboration with BAE Systems, this infra-red technology not only supports British troops in the most challenging environments but also promises to extend the life of the Challenger 2 tank beyond 2035. From a military perspective, this thermal imaging system has a notable history, having been deployed in Afghanistan to enable Chinook Helicopters to navigate mountain valleys undetected, even in adverse weather conditions. Moreover, it has empowered the detection, recognition, and identification of coalition troops or vehicles from a safe standoff range before they enter drop or landing zones.

Qioptiq Dragon S thermal weapons sight

The Qioptiq Dragon S (sniper) clip-on thermal sight stands as a ruggedized and uncooled thermal imager, equipping snipers with 24/7 surveillance and target engagement capabilities, regardless of adverse visibility conditions, total darkness, or battlefield obscurants. Remarkably, it boasts the capability to detect human-sized targets at distances of approximately 3 kilometers, rendering it invaluable to operatives. Additionally, the Dragon S incorporates a hot-swappable battery system, ensuring uninterrupted target tracking and adaptability for a variety of weapon mounting options, whether it be the Picatinny or NATO rail.

Moreover, Qioptiq’s Kite image-intensified weapons scope offers versatility as a stand-alone scope or an inline optic, maintaining pinpoint accuracy even during daylight. In peak conditions, it empowers users to detect individuals at distances of up to 2.5 kilometers, while the Maxkite-1 version further extends its prowess, enabling the detection of targets at impressive distances of up to 4.5 kilometers. This comprehensive range of optical solutions significantly enhances the situational awareness and operational effectiveness of military personnel.

Photonics-enabled medical imaging techniques hold immense potential for early disease detection.

Photonics is catalyzing a transformative shift in various fields, from medical diagnostics to autonomous vehicles and robotics. Employing principles like compressive sensing and computational imaging algorithms, advanced cameras leverage photonics to capture low-resolution images from multiple angles, amalgamating them into high-resolution imagery that outperforms traditional cameras. MIT researchers have showcased the impact of photonics on medical imaging, using laser-induced ultrasound to visualize biological tissue non-invasively, thus revolutionizing early disease detection and treatment monitoring.

In the automotive and robotics sectors, innovative solutions are emerging, exemplified by TriEye’s CMOS-based short-wave infrared (SWIR) image sensors and Coherent’s solid-state laser diodes. This collaboration pioneers a laser-illuminated SWIR imaging system with applications in vehicle cameras, industrial and autonomous robots, significantly enhancing situational awareness. TriEye’s Sedar (spectrum-enhanced detection and ranging) platform introduces high-resolution SWIR sensing that can detect and classify objects at greater distances, even in adverse weather conditions, without the need for moving parts, offering a novel approach for applications in automotive and robotics while prioritizing power efficiency.

Furthermore, Coherent has designed semiconductor laser diodes tailored for the Sedar platform, addressing limitations of LED-based modules, expanding the SWIR ecosystem. Operating in the SWIR wavelength range offers several advantages over NIR-based systems, including improved signal-to-noise ratios, heightened eye safety, and enhanced visibility in adverse conditions. The laser-illumination module contributes to the growth of SWIR imaging by providing a compact, reliable, and efficient light source.

The collaboration between Coherent and TriEye promises to unlock new applications for SWIR imaging, particularly in robotics, farming, construction machinery, and security systems, enhancing performance and safety. Prioritizing efficiency in power-constrained environments, their shared vision aims to drive SWIR lasers to higher levels of efficiency, ultimately closing the gap with NIR lasers and expanding the horizons of photonics in these industries.

The Future of Thermal Imaging

The applications of thermal imaging are diverse and continue to expand across various sectors, including defense, law enforcement, industrial, and commercial use. These technologies are breaking new ground in improving our ability to see clearly in the darkest, most challenging conditions.

As we look ahead, it’s clear that the power of thermal imaging will only continue to grow. With ongoing advancements in sensor technology, artificial intelligence, and miniaturization, the future promises even more remarkable capabilities. So, whether you’re on the battlefield or navigating your way through dense fog or smoke, thermal imaging technologies will remain your invaluable ally in unveiling hidden targets and ensuring safety and security.