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How does thermal imaging work

How Does Thermal Imaging Work?

From thermal binoculars to thermal scopes, there are hundreds of products that use thermal imaging to make night vision possible. These are popular among hunting enthusiasts security pros, and military members. But how does thermal imaging work in the first place? Let’s find out!

Have you ever pondered the question; how does thermal imaging work? If so, you’re in the right place!

This technology is pretty incredible; thermal imaging devices can detect temperatures as low as -40 degrees and as hot as to 3,600 F (2,000 C)!

Naturally, there are tons of uses for this kind of tech, so it’s not surprising you want to find out more on the subject. So, without further ado, let’s dive on in!

Thermographic image of a human face and neck showing different temperatures in a range of colors from blue cold to red hot. Red in the neck might indicate raised CR-P levels, this could be a sign of inflammation, and Carotid Artery inflammation which could be linked to a stroke.

A Bit of Background

Thermal imaging devices were initially used by sailors to detect icebergs, way back in the early 1900s!

Eventually, thermal imaging underwent numerous innovations so the military could harness this tech for military.

Then eventually, thermal technology arose for both civilians and police to use in complete darkness. These are especially handy for searching for missing persons and pets and launching rescue operations.For example, the applications of thermal binoculars and thermal monocular.

What is It?

Put simply; thermal imaging permits you to see a visual representation of the level of heat radiating from various objects that fall within the frame of the camera.

Then, each temperature is assigned a different color; this allows you to compare the various heats radiating off the variety of objects in the frame.

How Does it Work?

Let’s get into the nitty-gritty of how thermal imaging works. Thermal imaging involves a heat-sensitive camera that’s able to detect subtle changes in temperature.

Whether, you’re analyzing an object as small as a singular part of an electrical circuit, or as large as an office block; there’s a thermal imaging device you can utilize!

Now for the Techy Stuff

Here’s a brief breakdown of the tech involved:

The hotter an object is, the more infrared radiation it produces- simple right? This is crucial to bear in mind because thermal cameras can ‘see’ this radiation and then convert it into an image for us to see.

To achieve this, a unique lens is necessary. These can focus and detect the infrared light secreting from everything within its view.

Then, this light is further broken down and scanned by a plethora of infrared-detector elements (microbolometers). These are designed to capture and record the infrared emissions, and each pixel of the image has one.

These cleverly knit together to create a complete temperature pattern (also known as a thermogram). To create a complete picture, the camera takes and processes information from thousands of different points.

Fun Fact: On average, it takes roughly one-thirtieth of a second for a thermal imaging device to create a thermogram.

Last but not least, the microbolometers report the temperatures and assign each pixel of the thermogram an appropriate color.

What Do the Different Colors Mean?

Obviously, the different colors on the map indicate varying temperatures:

Cold temperatures are assigned the following colors:

  • Blue
  • Purple
  • Green

Whereas, hotter temperatures are usually associated with the following shades:

  • Red
  • Orange
  • Yellow

You get the idea!

Is There More Than One Thermal Imaging Device?

The short answer is, yes. There are two primary types of device:

  1. Un-cooled
  2. Cryogenically cooled

Let’s delve a deeper into the difference between the two:

1. Un-cooled

Un-cooled thermal imaging devices are the most common of the two types. The infrared-detector components are kept at room temperature inside the camera.

The device is virtually silent, immediately jumps into action, and has the correct battery pre-built into the model.

2. Cryogenically Cooled

Cryogenically cooled devices are way more expensive, and can’t withstand rough treatment. This system is sealed inside a unit that keeps everything below 32 F (zero C).

Although these devices are more fragile, they provide images with an incredible resolution which makes them worth the extra care and attention; so if accuracy is the aim, these are a sure bet!

Amazingly, cryogenically-cooled systems can detect differences as minimal as 0.2 F (0.1 C) from as far away as 1,000 ft (300 m)!

What’s Thermal Imaging Used for?

There are loads of uses for thermal imaging. For example:

Utility and energy business: these use devices to locate where houses are losing the most heat; with this knowledge, consumers can save money on their heating bills.

Police helicopters: use thermal imaging to find criminals and missing persons at night. You can detect unusual activity from a long distance, even in darkness and in adverse conditions like smoke, fog, woods, etc. This enables the police to approach unseen, and gather high-quality intelligence.

Weather stations: utilize these devices to track storms, hurricanes, and other freak weather forecasts. This intel goes a long way in helping people stay safe.

In medicine: thermal cameras are used to diagnose an array of ailments.

Home security systems and CCTV cameras: thermal imagery is sometimes used in conjunction as part of a broader network to provide the best possible service.

As you can see, thermal imaging is super useful!

How Does Thermal Imaging Work: Do You Now Have a Better Idea?

Do you now have an answer to the question; “how does thermal imaging work?” If you found this article useful, then we’re confident you’ll love the features published on our blog.

Alternatively, if you have any questions, comments, or queries about this blog post or about the subject more generally, then please feel free to reach out and contact us.

Or, if this blog post has inspired you to get a couple of gadgets of your own that utilize this fabulous technology, we thoroughly suggest perusing through our online store.

When somebody mentions cameras, most people will immediately think of ordinary cameras. Everybody is familiar with them – we know their purpose and what they’re capable of. What about thermal imaging cameras?

In recent years, these devices went from being something only seen in movies to commercially available products. Nowadays, thermal imaging cameras are used in many different sectors – construction, medical, industrial, law enforcement, and more.

How do these gadgets work? What can they detect? What features do they possess? How are they different from the night vision cameras? Keep reading – we have all the answers.

The Backstory

  • William Herschel (1738 – 1822) discovered the presence of infrared light in 1800. While studying the visible light spectrum, Herschel discovered that one form of light produces more heat than the others.
  • In 1929, Kálmán Tihanyi invented the very first infrared video camera. It was used by the anti-aircraft branch of the British Army.
  • In the 1970s, solid-state thermal-imaging arrays were invented. These were quickly upgraded to single-crystal-slice imaging appliances.
  • During the 1980s and 1990s, handheld units finally appeared. Unlike the earlier versions, these were more versatile and user-friendly.
  • However, it was only during the 2000s that these devices became cheap enough to be used by civilians. The production costs of uncooled arrays decreased, making these cameras a financially viable option.
  • As expected, this leads to a boom in popularity. Nowadays, thermal imaging cameras are used for applications such as autopiloting systems, environmental control, transport navigation, architecture analysis, emergency response, and more.

What is Thermal Imaging?

To put it simply, thermal imaging allows a person to see the heat that a particular object is radiating off itself.

Devices like thermal imaging cameras (also known as thermographic cameras) are capable of recording the temperature of the objects they’re pointed at. In order for the user to notice how much heat an object is radiating, these cameras assign different shades of color to different temperatures.

In almost all cases, warmer temperatures are given shades of yellow, orange, and red. Colder temperatures, on the other hand, are given shades of green, purple, and blue. For example, an object that radiates more heat than the surrounding objects will be redder.

Some cameras of this type use a greyscale. They can convert fine temperature variations into thousands of different shades of grey.

How Does Thermal Imaging Camera Work?

Thermographic cameras can recognize and capture different degrees of infrared light. In that way, they can detect temperature. Although it’s invisible to the naked eye, it is possible to feel infrared light as heat in case of high-enough intensity.

In nature, heat can be transferred in many different ways. The emanation of infrared radiation is one of them. When you’re holding hands over the fire, heat will be transferred to your hands through infrared radiation.

Objects that are hotter generate more infrared radiation. Thermographic cameras are capable of seeing this radiation. They can also convert it to images visible to the human eye. This principle of operation is similar to that of the night-vision cameras.

Much of the hardware of a thermal imaging camera consists of minute measuring devices. These are called microbolometers, and each pixel has one microbolometer assigned to it. Once the microbolometer detects the temperature, it gives its pixel an appropriate color. This is how a thermal image is created.

This complex construction is precisely why most of these devices use a low resolution. This is especially true when they’re compared to modern cameras, TVs, or smartphones. In fact, even the best thermal imaging cameras rarely go above the resolution of 640 x 480 pixels.

Types of Thermal Imaging Cameras

These types of devices can be separated into two categories:

Un-Cooled

Un-cooled thermal imaging cameras are common and widely used. The device operates at room temperature and uses batteries that are contained inside the unit. It’s a system that activates immediately and produces minimal noise.

Cryogenically Cooled

As their name suggests, these cameras have their elements sealed and cooled to subfreezing temperatures. This type of system provides better resolution and greater sensitivity. However, this also makes them more susceptible to damage, as well as more expensive.

What’s the Difference Between Thermal Imaging Cameras and Night-Vision Cameras?

Technically speaking, thermal imaging can be used to better perceive objects/persons in the dark. However, if you only want to see in the dark, a thermographic camera is overkill.

For example, thermal night vision can be of great use in police helicopters. This camera can easily discern people from the environment. As you may suspect, this makes it ideal for use in the dark, but can also be helpful for finding suspects who blended in with their surroundings in plain daylight.

However, thermal cameras capture longer wavelengths of infrared. This makes their manufacture more expensive. Night vision cameras rely on shorter wavelengths of infrared and are, therefore, cheaper to make. They can’t detect heat but allow the user to see in the dark.

Thermal Imaging Camera Applications

Originally developed for army use, these types of devices are now used for a variety of purposes. These are the most common applications:

  • Autopiloting systems
  • Animal & pest management
  • Architecture analysis
  • Firefighting
  • Law enforcement
  • Healthcare & medicine
  • Emergency response
  • Science & research
  • Security
  • Transport navigation
  • Electrical maintenance
  • Plumbing

What to Look for in a Thermal Imaging Camera?

The best thermal imaging cameras come in several varieties, ranging from personal to professional models. Their price depends on the quality of construction, as well as on bells and whistles they feature. If you’re planning to purchase one, ask yourself the following questions:

Accuracy – What level of accuracy of detection do I need?

Mass & Volume – Do I need a portable or stationary model?

Spectral Band – Which areas of the electromagnetic spectrum do I want to see?

Input Power – Will I be using batteries or AC power?

Measurement Modes – How many different measurement modes will I be using?

Screen Size – Do I need a large screen? What about touchscreen controls?

Resolution – How detailed do I need the images to be?

Image Overlay – Do I need image fusion and picture-in-picture functions?

Field of View – What angle should the lens detect?

Sensor Lifetime – How many images/hours should the sensor be rated for?

Video Storage – Live imaging only or video storage?

Wireless Connectivity – Will I be sending images to other devices?

Conclusion

Knowing how thermal imaging cameras work will allow you to put your model to greater use. However, these devices are much more user-friendly than before and can be operated by almost anyone. With time, they will become even more sophisticated and their applications and uses will increase further.

How does thermal imaging work

This article provides answers to the following questions, among others:

  • How do thermal imaging cameras work?
  • Why is the thermal image displayed in false colors?

Thermal imaging cameras are based on the same principle as the pyrometer. These cameras capture the radiation spectrum of an object, which then allows conclusions to be drawn about the temperature (see article Black-body radiation). In comparison to an infrared thermometer, however, the thermal imaging camera does not only detect the temperature at a single point but in a wide optical range and displays it.

Since the infrared radiation emitted by objects is not visible to the human eye, the radiation is converted into a spectrum visible to us and displayed. Since the image displayed by the camera does not correspond to the radiation actually emitted, one speaks of false colors in this context.

The figure below shows the thermal image of a driven car taken by a thermal imaging camera. The hot spots can be seen in white and the cold spots in dark blue.

Thermal imaging cameras are always suitable when the distribution of temperature is to be determined. They are used, for example, by the fire brigade to quickly identify potential sources of heat or fire.

How does thermal imaging work

Thermal cameras, when combined with video analytics, have long been considered the best way to detect people in the outdoors. At one time, they were used primarily only for the most critical sites. But innovations and advancements, along with price reductions, now make them available for more common security applications, like for preventing theft and vandalism. We’ve written this article to help explain how a thermal imaging camera works and why it represents a great choice for outdoor security.

Thermal Imaging Cameras “See” Heat

Our eyes work by seeing contrast between objects that are illuminated by either the sun or another form of light. Thermal security cameras work by “seeing” heat energy from objects. All objects – living or not – have heat energy that infrared cameras use to detect an image. This is why a thermal imaging camera can operate at all times, even in complete darkness.

Because they act like a heat vision camera rather than one which uses reflected light, thermal images look very different than what’s seen by a visible camera or the eye. In order to present heat in a format appropriate for human vision, thermal security cameras convert the temperature of objects into shades of gray which are darker or lighter than the background. On a cold day a person stands out as lighter because they are hotter than the background. On a hot day a person stands out as darker because they are cooler than the background.

Outdoor challenges for thermal imaging cameras

For these reasons, thermal energy cameras are known for “seeing in the dark” because at night background objects tend to be cooler than a person at 98.6 degrees. Under ideal conditions, people are well emphasized at night because they appear brighter than the background and stand out, even in zero light.

However, outdoor security conditions are rarely “ideal”, especially during the day when darker objects absorb the sun’s energy and heat up, an effect known as thermal loading. When objects in the scene become uniformly hot in any given area, many cameras have difficulty presenting the narrow range of temperature differences into a useful image. The result is sometimes an image with large areas that look “whited out” or “grayed out” and undefined. This makes it difficult to see what is happening in the scene, and can make it difficult for video analytics to detect intruders accurately.

How does thermal imaging work

Thermal Loading Can Cause Blurry Images

To help illustrate, the capture shown depicts a daylight image from a thermal video camera which cannot effectively compensate for white-out from thermal loading. Details such as the power lines, pavement, and other objects have become impossible to discern due to the effect of thermal loading. It’s even difficult to tell that this is a daytime image. In this situation, with cameras not designed to deal with thermal loading, the video analytics will have a difficult time detecting intruders with the reliability needed for security.

How Video Processing Makes Thermal Video Cameras Work Better

Thermal imagery is very rich in data, sensing small temperature variations down to 1/20 th of a degree. Thermal imaging cameras must convert these fine temperature variations – representing 16,384 shades of gray – into about 250 gray scales to more closely match the capability of human vision to decipher shades of gray. Such compression is also used by some camera to send video over the network for video content analysis.

The image below shows the difficulty distinguishing between close levels of gray. The top row shows six levels of gray which the eye can see. The bottom row shows sixteen shades of gray – you can see how it is increasingly difficult to distinguish where the shades transition from one block to the next. Consider the fact that a thermal imager has 16,000 shades of gray, over 1000 times more than show in the lower bar graph, and the magnitude of the problem becomes clearer.

How does thermal imaging work

In the past, most cameras converted this data in a simplistic way by mapping gross areas together that are close in temperature. This is why thermal images often look blurry, lack detail and conceal intruders, while the analytics would often misdetect intruders entirely.

New heat sensor cameras with a high-level of image processing can emphasize small variations between objects and the background to exaggerate the fine details in contrast to other image features, while automatically detecting intruders accurately, every day, every night, under all outdoor conditions.

The image below shows how image processing can overcome outdoor issues and provide a very clear thermal image. The left shows a camera which lacks the processing to create good contrast and displays objects as “whited out.” On the right, the same image has been intelligently remapped by image processing to emphasize the small temperature differences in the hotter objects, presenting an image that approaches a black and white photo, which will better reveal potential intruders.How does thermal imaging work

Using Thermal Imaging Cameras with Video Analytics

Combining thermal imaging cameras with video processing is a great way to improve their ability to work better under even difficult conditions. When paired with video analytics, they can detect intruders over very large outdoor areas, ignoring all the movement – headlights, reflections, small animals, trees and blowing trash – that cause alarms with visible light cameras. This means that you can detect more reliably, over larger distances, even in difficult situations.

This is why SightLogix incorporates a high degree of processing power inside our smart thermal cameras. This processing is used to filter the effects from wind, lighting, precipitation, moving clouds, shadows and vibrations from causing nuisance alerts. The system’s ability to accurately detect intruders with minimal nuisance alarms is the reason many organizations have come to trust SightLogix for their outdoor security applications.

Thermal images cannot see through walls, although you can gather much information about the inside of the wall as well as what is happening on the other side of the wall. For example you would not be able to see people and plants involved in an illegal indoor growing operation from the outside of the building. You would be able to see and monitor the heat escaping from the building that would be a telltale sign of an illicit growing operation. Click here for legal cases involving thermal infrared for narcotics detection

You would also be able to see things like studs inside the walls, or damaged insulation in roofing applications. You cannot hide from thermal imaging by covering yourself in mud to blend in like that movie tough guy. This might work momentarily, but infrared “heat” energy transfers well when objects are touching. Your body heat would quickly warm your camouflage resulting in a thermal image. We hope that dispels a few of the most common questions regarding infrared energy. Thermal imagers in Hollywood and in real life are very different. The remainder of this paper will focus on the real life thermal imagers and how they work.

Thermal energy is transmitted in the infrared wavelength ( 1 micron to 100 microns ). You can see by the image above that thermal energy is closely related to visible light in that it travels in a wave. The human eye can only see the narrow middle band of visible light that encompasses all the colors of light in the rainbow. Thermal infrared imagers translate the energy transmitted in the infrared wavelength into data that can be processed into a visible light spectrum video display. Visible light is dependent on a light source ( the sun or artificial ) reflecting off an object to be received by our eyes. Remember, all objects above 0 degrees Kelvin emit thermal infrared energy so thermal imagers can passively see all objects regardless of ambient light. This can give you an enormous advantage. Thermal infrared imaging performs in a wider range of environments than other night vision technologies. Additionally, IR devices can serve your inspection needs at night or in broad daylight.

How does thermal imaging workThe image on the left shows two adults and a child through an infrared thermal imager. After a minute of sitting on the couch the thermal infrared energy of the people is transferred and stored in the couch until they get up. The image on the right illustrates the fact that all objects radiate heat. The heat from their bodies that transferred to the couch is now being emitted from the couch and displayed on a thermal imaging device. No visual light technology can record this type of data. The properties of heat transmission are more than an interesting novelty, this information can prove useful in a variety of applications. Law enforcement applications include criminal tracking, land/airborne surveillance, drug facility detection, or vehicles which have been recently operated all from a safe distance, industrial users can detect flaws in manufacturing or weakened insulators, fire safety professionals can detect full vs. empty flammable storage containers, and forestry workers can easily track game or poachers. Other applications include non destructive testing, process control, predictive/preventative maintenance, building/factory diagnostics, energy audits, roofing/insulation inspection, insurance fraud prevention, veterinary/human medical imaging, border patrol, remote security monitoring, and many more applications being discovered.

Thermal infrared imagers come in different configurations to suit your specific needs. Some imagers are designed to give you actual temperature measurement of the scene along with a color video representation. This type of imager is called “radiometric” and is used mostly for industrial ( predictive maintenance, process control, R&D ) and medical ( human & veterinary ) applications. Other imagers are designed primarily for surveillance and / or target acquisition environments. These units can be either hand held or fixed mount remote installations. The chief differences in surveillance units is going to be the optical components and the resolution of the imager. High end units for surveillance and target acquisition scenarios are capable of human detection at over 1 mile and vehicle detection at over 5 miles. Another type of detector is the aerial surveillance mounted thermal imager. These units are mounted to aircraft in gyro stabilized all weather housings. Typically they are remote controlled and are either alone or paired with a CCD TV camera. Primarily these units are used by law enforcement agencies and electronic news gathering teams.

How does thermal imaging workCan You Explain Thermal Imaging?

Thermal imaging is a method of improving visibility of objects in a dark environment by detecting the objects’ infrared radiation and creating an image based on that information. At ACS Underground Solutions we believe Thermal Imaging is an excellent tool that complements any leak detection strategy. Water which is a colorless, transparent, odorless, tasteless liquid always chooses the path of least resistance so a thermal imaging service can help identify the often mysterious origin of water leaks and steam leaks.

How Does Thermal Imaging Work?

All objects produce infrared energy as a function of temperature. The infrared energy that is released by an object is known as its heat signature. The hotter an object is, the more radiation it produces. A thermal imager is essentially a heat sensor that is capable of picking up tiny differences in temperature. The imager collects the infrared radiation from objects in the scene and creates an electronic image based on information about the temperature differences. Because objects are rarely precisely the same temperature as other objects around them, a thermal camera can detect them and they will appear as distinct in a thermal image.

What Are The Benefits Of Thermal Imaging?

  • Water infiltration (roof leaks located with recent rain fall within 24

48 hours)

  • Cold air infiltration
  • Excessive moisture in building materials
  • Stud / Joist / Beam / Rafter placement and structure
  • Insulation gaps, insufficient and unevenness
  • Electrical drops, panels, breakers, switches and wire connections
  • Heating and cooling duct placement, insulation, air leaks
  • Pipe location
  • Special Inspections
    • Pest infestation
    • Energy audits
    • Insurance claims
  • What Are The Common Uses of Thermal Imaging?

    • Building Heat Loss: Find and reduce sources of energy waste
    • CMU Wall Inspection: Detect and document structural deficiencies
    • Electrical Infrared Inspection: Detect electrical system overloads
    • Mechanical Infrared: Locate excess friction and wear on mechanical parts
    • Radiant Heat Leak Detection: Locate leaks in hot water and radiant heat systems and floors
    • HTHW Leak Detection: Locate High Temperature Hot Water (HTHW) leaks
    • Steam Leak Detection: Find costly steam leaks
    • Underground/Under Slab Pipe Leaks: Pinpoint leaks and prevent random digging

    ACS Underground Solutions | Thermal Imaging Services

    ACS Underground Solutions is private family owned consulting company with decades of experience and expertise in Underground Utility Locating with GPR, Underground Storage Tank Locating, Concrete Imaging & Scanning, Drain Pipe Inspections and Infrared Thermal Imaging Services. ACS Underground Solutions serves Connecticut, New York, New Jersey, Massachusetts, and Rhode Island.

    CALL ACS AT 203.544.7190 OR Email ACS Underground Solutions TO LEARN MORE.

    How does thermal imaging work

    Popular media has been responsible for a wealth of misinformation throughout the years about thermal—or infrared—imaging. What exactly can thermal cameras “see” through? To answer that, here’s a rundown of the most commonly asked questions we receive about what you can and can’t see through using a thermal camera.

    (Knowledgeable individuals might point out that thermal cameras don’t “see” anything: they detect heat and then assign colors based on the range of temperatures detected by the sensor. However, we’ll use it as a shorthand in this article.)

    Can thermal imaging see through walls?

    No, thermal cameras cannot see through walls, at least not like in the movies. Walls are generally thick enough—and insulated enough—to block any infrared radiation from the other side. If you point a thermal camera at a wall, it will detect heat from the wall , not what’s behind it. However, if something inside the wall causes enough of a temperature difference, a thermal imager will be able to sense it on the surface of the wall. Building maintenance professionals often use thermal imagers to detect issues like water leaks or missing insulation without needing to tear down walls to assess the problem.

    Studs inside the wall (vertical lines) are colder than the insulation, causing a temperature difference on the surface of the wall.

    Can thermal imaging see through smoke?

    Yes, thermal cameras can detect heat through smoke, and are widely used by firefighters for this purpose. Soot particles in smoke effectively block visible light, but allow infrared radiation to pass through, letting firefighters or other first responders navigate through smoke-filled environments.

    How does thermal imaging work

    The person in the doorway is concealed by smoke in the visible light spectrum, but easily detected by thermal imaging.

    Can thermal imaging see through fog?

    Fog and rain have the potential to severely limit the range of a thermal camera due to the scattering of radiation off water droplets. However, in many circumstances, thermal cameras can penetrate fog much more successfully than visible light cameras or the human eye. This is one reason why car manufacturers are incorporating thermal imagers into the sensor suites of autonomous vehicles.

    Under certain circumstances, thermal imaging can detect objects through fog much more clearly than visible light detectors.

    Can thermal imaging see through glass?

    Fun fact: glass acts like a mirror for infrared radiation. If you point a thermal imager at a window, you won’t see anything on the other side of the glass, but you will get a nice reflection of yourself in thermal. This is because glass is a highly reflective material, meaning it shows the reflected temperatures of objects rather than letting infrared radiation be transmitted through. The same principle applies to other reflective materials, like polished metal.

    How does thermal imaging work

    The digital camera sees through the glass to the trees outside, while the thermal camera sees the reflected heat of the photographer.

    Can thermal imaging see through concrete?

    The answer to this question is basically the same as the question for walls—no, but a thermal camera might be able to detect something inside the concrete like a pipe or radiant heating that causes a temperature difference on the surface of the concrete.

    Radiant underfloor heating is clearly visible under a concrete floor.

    Can thermal imaging see through metal?

    Metal can be a tricky material in the thermography world. Shiny metal—any metal object that is smooth or polished—will reflect infrared radiation, acting as an infrared mirror just like glass. This can cause difficulties for anyone trying to monitor pipes or machinery for overheating parts. Oxidized metal or metal that has been painted with a matte material is much easier to measure accurately (check out our article Using Low-Cost Materials to Increase Target Emissivity to learn more). In all cases, thermal cameras can never see “through” metal objects, but conductive metals might reveal hot spots, cold spots, or the level of a substance inside a metal container.

    How does thermal imaging work

    It’s easy to see how full these tanks are in infrared because of the temperature difference on the metal surface caused by the liquid inside.

    Can thermal imaging see through trees?

    A thermal camera can’t detect objects through the trunk of a tree, but thermal can help with spotting people or animals in forested areas. Search and rescue teams often employ thermal imaging to spot heat signatures when searching through large tracts of wilderness.

    Thermal imaging cannot see through trees (or wood), but it can be helpful for spotting people in forested areas where their heat signatures stand out much more than a visible image might.

    Can thermal imaging see through plastic?

    A fun party trick to perform with a thermal camera is to hold up a thin, opaque sheet of plastic (like a garbage bag) in front of a warm object or person. Infrared radiation will pass through the plastic, allowing the thermal camera to detect whatever is behind it, while visible light will be blocked. However, this trick only works with very thin plastic—thicker plastics will block infrared radiation.

    How does thermal imaging work

    Visible light is mostly blocked by the plastic bag, but infrared radiation is transmitted.

    Can thermal imaging see in the dark?

    Final bonus question! The answer: yes! Thermal imaging is not affected by darkness at all, requiring no visible light to visualize heat. (Check out our article on Thermal Imaging vs. Night Vision to learn more.)

    How does thermal imaging work

    CCTV footage vs thermal imaging demonstrates that thermal requires no visible light to form an image.

    How does thermal imaging work?
    Thermal imaging cameras detect heat, whereas normal digital cameras have sensors which detect light. On a thermal imaging camera, a special lens focuses the heat (infrared energy) given off by an object onto a detector which is sensitive to heat. Therefore thermal imaging will work both in daylight as well as in complete darkness as it is unaffected by light.

    Can thermal imaging see through objects/does it work like X-Ray Vision?
    No – because thermal imaging only detects heat, it will not ‘see’ through solid objects, clothing, brick walls, etc. It will see the heat coming off the surface of an object. In fact, thermal imaging technology cannot see through glass, either. Because of this, the lenses on thermal imaging cameras have to be made of a special element (Germanium) and not from glass. This makes the lenses of thermal imaging cameras more expensive than regular camera lenses. Contrary to popular belief, thermal imaging cannot really see through somebody’s clothing.

    How far can thermal imaging cameras see?
    This depends on a number of factors:

    1. How large and how hot the object is you are looking at
    2. The size (resolution) of the detector in the thermal imager
    3. The pixel pitch of the detector (how far apart each pixel is on the detector – this is measured in microns – the closer together they are, the higher the thermal image quality)
    4. The type/size of lens being used on the thermal imaging camera
    5. The weather conditions

    To give a rough idea: A Thermoteknix TiCAM 750MR (Medium Range) Thermal Imaging Binocular with a 75mm lens and a 384 x 288 resolution detector with a 17µ pitch can detect a man at 2km in standard weather conditions.

    What is thermal imaging useful for?

    Energy Efficiency
    For example, thermal imaging can be used to see how much heat is escaping from a house/building and to check how well insulated that building is or to monitor water ingress in buildings (dampness shows up as cold on brickwork/plaster/flooring, etc).

    Police and Law Enforcement
    For example, to see fugitives hiding in darkness or under the cover of trees, to see if a car is warm which would suggest it had been driven recently, to follow vehicles at night (e.g. from a helicopter). Thermal Imaging can detect such slight difference in temperatures that it can even see, for example, the heat left by skid marks from a recently departed vehicle. Police also use thermal imagers to look at houses where it is suspected that a cannabis farm is operating as they tend to give off more heat than neighbouring buildings – especially from the roof generally. Small differences in temperature can indicate hidden compartments in walls and my show if somebody is concealing a weapon or gun under their clothing.

    Mountain/Fire/Rescue
    To find people/bodies lying injured in remote or other areas/burning buildings/natural disaster zones such as earthquakes/floods. Thermal Imaging will also see through fog/smoke. It is also used for detecting forest fires.

    Surveillance/Reconnaissance/Border Control
    To see movement/presence of people/vehicles. It is also widely used in maritime environments for the same purpose.

    Industry
    For monitoring hotspots in electrical equipment (Predictive Maintenance) and for monitoring high temperature processes such as in boilers, furnaces/kilns. Thermal Imaging is routinely used in the monitoring of cement kilns.

    Defence/Military
    For seeing in the darkness for combat environments and for general situational awareness.

    Medical/Veterinary
    For seeing differences in body temperature – inflammation in the body of a mammal creates extra localized heat which is visible/detectable by a thermal imaging camera.

    Motorsport/R&D/Scientific
    Thermal imaging is used in so many applications in this area that it is almost impossible to list them all. However, F1 and Indycar racing teams use thermal imaging cameras to monitor the heat of the tyres on their cars to optimize traction, to track the heat signature of missiles, to film lions hunting at night and NASA even used Thermoteknix thermal imaging cameras to look for water on the moon (and they found it!).

    What is the difference between Night Vision and Thermal Imaging?
    Night Vision (also known as I 2 or Image Intensification) relies on at least a very low level of light (less than the human eye can detect) in order to amplify it so that it can produce a picture. Night Vision will not work in complete darkness whereas thermal imaging will because it only ‘sees’ heat.
    To summarise, Night Vision is good for identification purposes, can see through glass but cannot see in complete darkness. Thermal Imaging cannot see through glass, but can see in complete darkness, it is therefore a more powerful detection technology, cannot be blinded by light and can see through fog and smoke. Combine the two technologies into Fused Night Vision with, for example, a Thermoteknix ClipIR Thermal Imager Clip On device and you have the best of both worlds.

    Thermal Imaging

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    How does thermal imaging work

    Kilauea on the Island of Hawaii is one of the most active volcanoes in the world. In late April 2018, the volcano started showing signs of increased activity. On May 3, 2018, the first crack, also known as a fissure, opened up followed by 19 more fissures, for a total of 20. The activity sparked widespread attention as images circulated of lava flows and destruction on the island.

    Since then, news and information provided by the United States Geological Survey (USGS) and their Hawaii Volcano Observatory has escalated, and on May 15, 2018, the USGS alert level changed from “orange” to “red” indicating a “major volcanic eruption is imminent, underway, or suspected with hazardous activity both on the ground and in the air.”

    Scientists collect a variety of critical information and data to better understand erupting volcanoes, including temperature measurements from handheld thermal imagers. They use the information to help make potentially lifesaving predictions. The United States has approximately 169 active volcanoes and there are about 1,500 worldwide.

    Capturing Thermal Energy at Kilauea

    Much of the monitoring activity performed by the USGS is gathered from instruments installed during inactive times, many of them temporary. However, when volcanic activity increases, so does the opportunity for the USGS and other interested organizations to gain hardcore information about how volcanoes act in real time.

    USGS scientists collect data using an assortment of aerial (aircraft), orbiting (satellites) and handheld sensing instruments, such as thermal imaging cameras. Once the data is collected, it can be analyzed and used to predict future eruptions.

    “There are many advantages to taking measurements using a handheld thermal camera,” said Steve Lundblad, Chair of the University of Hawaii at Hilo Geology Department. “USGS scientists must often have their wits about them when entering some of these potentially dangerous areas. With a portable thermal imager, data can be captured instantly and easily as events unfold in real-time. Using other methods to measure temperature might require the extra time to install and recover the equipment.”

    An example would be thermal couplers, which must be physically placed in the ground and then removed once the measurements have been taken. A thermal IR imaging camera, however, offers a non-contact way to quickly measure temperatures.

    “It’s worth it for the USGS to collect thermal infrared (IR) image measurements when possible,” said Lundblad. “Because of the length of time they’ve been capturing and analyzing data from other eruptive episodes, the USGS has been able to make accurate predictions about Kilauea’s movements and behaviors. Knowing what the volcano will do next has been very helpful in keeping citizens safe.”

    Making sure surrounding communities stay safe and informed during volcanic eruptions is paramount to successfully managing the event. In addition to USGS operations and the observatory, critical groups such as the Hawaii Civil Defense provide crucial warnings and informational messages, including the possible need to evacuate. The USGS also strives to keep its scientists safe.

    “A decision about whether to take measurements or not in certain areas is likely done on a case by case basis,” said Lundblad. “For instance, fissure No. 17 has been extremely active and spewing huge lava bombs, and therefore too dangerous to get very close to. However, valuable data can still be taken from other less volatile vents or fissures to help predict the possibility of a recurring episode.”

    How does thermal imaging work

    How do IR cameras work?

    Unlike regular cameras, which capture visible light to create pictures, thermal cameras create images by detecting the amount of IR energy an object emits, such as the energy radiated from a lava flow. The thermal camera uses infrared-sensitive sensors to detect the IR energy and converts it into a thermal image. It also assigns colors to the differing temperatures to indicate variations, such as hot spots.

    Measuring thermal energy from a distance

    Thermal imaging devices mounted on aircraft and satellites also collect measurements for the USGS. Each method, whether up-close or from a distance, has an optimum time and place for use, depending on volcanic conditions.

    As with field-based monitoring, where safely capturing thermal activity can sometimes be dangerous, capturing thermal images from a distance also has disadvantages because of its reliance on favorable weather and atmospheric conditions. For instance, fissure No. 20 is producing large amounts of ash plumes and therefore, obstructing camera visibility and causing unreliable measurements.

    Trying to pinpoint the exact time of volcanic eruptions is still not possible, however, thermal imaging cameras greatly assist USGS scientists by capturing valuable data for current and historical reference. The more USGS scientists can understand how volcanoes behave during inactive and active times, the closer they can come to determining exactly when a volcano will erupt.