Hot technology: Guide to thermal imaging and IR cameras
Reading time: 10 minutes
Sometimes, there’s more to our tools than first meets the eye. And in the case of thermal imaging, we mean that quite literally. Today, we’ll explore the surprisingly extensive field of thermal imaging and infrared energy use in business and discuss some of the technology’s “hottest” applications.
What is thermal imaging?
Thermal, infrared, or thermographic imaging describes both the practice and technology behind detecting and visualizing infrared energy (heat) in the environment around us.
Unlike some other animals (insects, snakes, bats), humans can’t see infrared without the use of specialized equipment because it falls just below the range of wavelengths visible to our eyes (infra = below). Nevertheless, we know it’s there.
Types of infrared wavelengths explained
Infrared radiation can be broken down into three wavelengths:
Short-wave (1.3 – 2.5 μm) – Used in night vision goggles.
Mid-wave (3.0 – 5.0 μm) – Used in long-range surveillance.
Long-wave (8.0 – 14.0 μm) – Used in most infrared cameras.
We’ll discuss how we first found out in another section, but for now, let’s just say we have convection and conduction to thank. You see, the universe is in a constant struggle to maintain equilibrium (i.e., balance). Therefore, warm things expel heat to cool down (convection) and cold things take it in to warm up (conduction).
Example: If you want to see this constant struggle for yourself, or explain it to your little one, go to the freezer and grab an ice cube. The cube will cool down your hand and melt at the same time until only water matching your body’s temperature remains.
How do infrared cameras work?
At a glance, traditional (both analog and digital) and infrared cameras may seem similar. After all, they’re all made up of the same basic components – a lens, sensor, processing electronics, and mechanical housing.
However, the way these cameras work is very different. Regular daylight cameras, like the human eye, work as follows:
Because infrared cameras have to focus longer wavelengths, the thermal sensors they use have to be much larger. Consequently, infrared cameras tend to have much smaller resolution compared to their visible light counterparts (anywhere between 80 x 60 – 1280 x 1024 pixels).
However, outside a very niche field of photography, the comparably low quality of infrared cameras isn’t really a problem – as we’ll discuss, that’s not their purpose. What’s more important is that they allow people to view objects even in low-light conditions or through pollutants (like smoke).
Professional thermal imaging equipment is able to identify differences in heat signature (the infrared energy an object emits) as small as 0.01°C and display it either as shades of grey or via varying color palettes.
The history of thermal imaging
Before we discuss the history of thermal imaging and infrared cameras, we should take a look at the humble beginnings of IR itself. Infrared radiation was first discovered by the astronomer William Herschelin the early 19th century and presented before the Royal Society in London in 1800.
Herschel accidentally both discovered IR and inspired the cover of Pink Floyd’s Dark Side of the Moon while experimenting with a prism.
After placing the glass object under sunlight, it broke down the rays into various colors of the spectrum. However, despite nothing being visible beyond the red light, Herschel detected a heat spike on his thermometer.
The scientific community spent the following years experimenting with infrared, studying the laws governing it, and seeking potential applications. Initially, IR’s use was limited to thermometers and bolometers (devices measuring heat based on a material having temperature-based electrical resistance).
Then, a breakthrough came in 1829, when Leopoldo Nobili created the first thermocouple (thermometer based on the difference in temperature-based electrical current) and thermopile (device converting heat into electrical energy) by connecting multiple thermocouples together.
In 1833, Nobili’s colleague Macedonio Melloni improved on the former’s designs and created a more sophisticated thermocouple that could detect a person <10 meters away. Just 7 years later, Herscher threw his hat back into the ring and created the first thermograph – a picture developed from infrared energy.
Finally, in 1901 Samuel P. Langley and Charles G. Abbott created a bolometer that could detect the heat signature of a cow 400 meters away. No one knew it yet, but the birth of the infrared camera was fast approaching.
History of infrared cameras
Following these inventions, the first applications for IR were developed in the civil section – for detecting icebergs in 1913 and identifying forest fires in 1934. Meanwhile, the British implemented the first night-vision anti-aircraft television camera in 1929.
The United States followed “soon” after in 1947, creating a thermographic camera based on an infrared line scanner that took an hour to develop a photo. The next significant development was in 1965 when the first commercial camera was sold for high-voltage power line inspections.
Nevertheless, until the early 1990s, the use of IR was mostly limited to military operations. Following major developments in smart sensors and the lowered costs of uncooled arrays (detectors/sensors that don’t need cryogenic cooling to function), thermographic cameras entered the commercial mainstream.
And that leads us to…
The use of thermal imaging cameras across industries
Finally, we arrive in the world of today. As we’ve seen, up till now, the use of infrared cameras has been very limited. However, that’s changed significantly in the past 3 decades. Nowadays, IR enjoys widespread application, across many industries.
IR in inspections and maintenance
The preventive maintenance (PM) field sees some of the most extensive thermal imaging use of all industries. The technology is leveraged in:
Hotspot detection in electrical systems: IR can quickly identify overheating components, loose connections, or faulty electrical wiring in panels, transformers, and other equipment, making it invaluable in preventing electrical fires and equipment malfunction.
Mechanical equipment maintenance: Targeting primarily bearings, motors, pumps, and valves; IR can detect temperature anomalies, blockages, and other associated wear and tear. This allows maintenance teams to prevent overheating, address lubrication issues, and save significantly on repairs.
Building inspections: Thermographic equipment is often utilized to detect moisture damage and evaluate insulation efficiency. Among other uses, this allows companies to assess structural integrity in floors, walls, and roofs alike; and improve the energy efficiency of buildings.
HVAC system maintenance: Thermal cameras can help visualize air leaks, check for blockages in ducts, and ensure proper heat distribution by tracking its spread through radiators.
Pipeline inspections: In the oil and gas industry, maintenance workers leverage thermal imaging to remotely view pipelines (even underground or underwater) and inspect them for blockages, leaks, and other abnormalities; helping prevent environmental damage and costly repairs.
IR in construction
As described in a previous point, infrared cameras are very important in the construction industry for quality assurance, preventive maintenance, as well as documentation. Their use cases include:
Concrete and asphalt quality control
HVAC system inspections
Structural integrity evaluations
IR in manufacturing
Thermography is also very important in the manufacturing industry for troubleshooting, preventive maintenance, process optimization, and other associated activities. Some of its most valuable uses include:
Quality control & inspections: Including product, surface, welding, electrics, and composite materials evaluations. Like before, this also applies to energy audits, preventive maintenance, etc.
Process optimization: In industries like plastics, metallurgy, and food processing, thermal cameras are highly valuable for temperature monitoring, heat treatment, and injection molding.
Material testing: IR technology is used for non-destructive material testing. It can detect material defects, assess material properties, and identify stress concentrations in manufactured components.
Safety: In manufacturing, IR cameras are used for safety inspections to identify overheating equipment, electrical faults, and potential hazards that could pose risks to workers or equipment.
Product development: Researchers and engineers use IR technology during product development to study how heat is distributed and dissipated in prototypes, which helps in the design and improvement of products.
IR in healthcare
Due to infrared’s ability to carry out non-invasive diagnostics and health screenings, it’s widely used within the healthcare industry across a variety of departments – though typically in conjunction with other medical equipment and techniques.
It can be used in:
Fever screening: Thermal cameras can quickly scan large groups of people and identify individuals with elevated body temperatures, which could be indicative of a fever.
Cancer screening: IR can detect temperature variations in tissue, that may indicate abnormal blood flow and potentially highlight areas due for further inspection.
Wound healing assessment: Infrared cameras can also help evaluate the effectiveness of treatments by monitoring the temperature of wounds, which highly correlate with the body’s immune system response.
Vascular health evaluation: Infrared imaging can assist in the assessment of vascular conditions, including identifying varicose veins or assessing peripheral vascular diseases by visualizing blood flow patterns.
Neurology: Thermal cameras can help neurologists assess conditions like migraines or reflex sympathetic dystrophy (RSD) by visualizing temperature changes in the affected areas of the body.
Rheumatology: Rheumatologists may use thermal imaging to help diagnose and monitor conditions like rheumatoid arthritis, which can be associated with temperature variations in joints.
Dentistry: Infrared cameras can be used in dentistry to identify inflammation and infection in oral tissues. They can also assist in assessing dental restorations for signs of wear or damage.
Infection control in health clinics: Thermal cameras can be used to monitor surface temperatures in healthcare facilities to identify areas of potential infection risk. This can help healthcare providers take appropriate precautions to prevent the spread of contagious diseases.
IR in emergency response
Thermography is also highly important in emergency response, specifically when dealing with various natural disasters. Its life-saving properties can be put to good use in:
Firefighting: IR cameras can detect hotspots and fire sources in smoke-filled environments where traditional visual cameras would be ineffective. This allows firefighters to quickly identify the location and intensity of fires.
Search & rescue: IR cameras can detect the heat signatures of missing persons, even in challenging conditions such as dense forests, at night, or in adverse weather. This makes them invaluable in all environments and situations, including avalanches, collapses, maritime accidents, etc.
Law enforcement: Law enforcement agencies use IR technology to track and apprehend suspects, especially at night or in low-light conditions. It can also be used to monitor large crowds for safety and security.
The main takeaway
As you’ve had the opportunity to see, thermal imaging is a highly functional technology with a rich and varied history. Thanks to the rapid development of the last 2-3 decades, IR’s become a mainstay of military and civilian applications alike.
And for good reason! It can give you new, non-invasive ways of assessing the situation anywhere from the production floor of a manufacturing plant to the emergency room of a hospital, or snowy terrain of search and rescue.
We fully encourage you to explore the applications of infrared cameras in your industry and wish you the best of luck. The saved costs on preventive maintenance and streamlined operations are more than sure to be worth it.
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