I guarantee this will be your first image when you unpack your Thermal Imaging Camera and try it out.
Alongside frequently asked questions about how thermal imaging cameras work in general, there are also a number of common queries regarding specific use scenarios and the effectiveness of the technology in particular environments or applications.
In this section, we’ll examine a few of the better answers and the reasoning behind them.
Why do thermal imaging cameras work better at night?
Thermal imaging cameras tend to work better at night, but it has nothing to do with the state of the surrounding environment being light or dark.
Rather, because the ambient temperature - and, more importantly, the core temperature of otherwise-unheated objects and environments - is nearly always significantly lower at night than during sunlight hours, thermal imaging sensors are able to display warm areas at higher contrast.
Even on relatively cool days, heat energy from the sun will be gradually absorbed by buildings, roads, vegetation, construction materials, and more while ever it’s daylight outside.
And, for every degree these sorts of objects gain in ambient temperature over the course of the day, they become less clearly distinguishable from other warm objects the camera’s sensor is being used to detect and highlight.
For the same reason, most thermal imaging cameras will display warm objects in sharper contrast after several hours of darkness, rather than just after the sun sets - and, even during full daylight hours, they’ll usually be more effective in the early morning than in the middle of the afternoon.
Do thermal cameras work through glass?
You may be surprised to learn that thermal imaging cameras don’t generally work through glass.
A full explanation of the technical reasons for this would be somewhat complex from a physics standpoint, but the principle is pretty straightforward. In essence, a sheet of glass allows visible light through but acts a bit like a mirror for infrared wavelengths (this is why the lenses on IR cameras are commonly made from germanium or zinc selenide, not glass).
An infrared, IR or thermal imaging camera works by detecting and measuring the infrared radiation emanating from objects - in other words, their heat signature.
In order to do so, the camera must first be fitted with a lens that allows IR frequencies to pass through, focusing them on to a special sensor array which can, in turn, detect and read them.
The sensor array is constructed as a grid of pixels, each of which reacts to the infrared wavelengths hitting it by converting them into an electronic signal. Those signals are then sent to a processor within the main body of the camera, which converts them using algorithms into a colour map of different temperature values. It’s this map which is sent on to be rendered by the display screen.
Many types of thermal imaging camera will also include a standard shooting mode that works with the visible light spectrum, much like any other point-and-click digital camera. This allows for easy comparison of two identical shots - one in IR and one in normal mode - to help quickly identify specific problem areas once the user steps out from behind the lens.
If you were to point a thermal detection camera at a window, what you’d see onscreen wouldn’t be a clear thermal rendering of what’s on the other side, but most likely a blurry mess - and possibly a vague reflection of yourself holding the camera! and not anything Paranormal either.
Civilian application of FLIR technology using "IR Mode".
Do thermal cameras work underwater?
Not that you ever would on a paranormal investigation.
Thermal cameras don’t tend to work well underwater. The reasons are, in part, related to the issues with glass outlined above.
Water blocks a lot of infrared wavelengths, much as an opaque barrier blocks visible light wavelengths. In the same way that we can’t see through paint, infrared sensors can’t ‘see’ through any significant depth of water, because the waves it detects don’t pass through water easily.
Water also provides another challenging issue for IR cameras, related to thermal conductivity and specific heat. Water has a much higher heat capacity than air, requiring four times as much energy to raise or lower the temperature of an equivalent volume by one degree.
In practical terms, this means that objects lose (or gain) their own heat energy relative to water much faster, and over shorter distances. For thermal imaging purposes, objects are therefore naturally harder to differentiate when submerged than they would be in the air.
Can thermal imaging cameras see through walls?
Well, no - but to be fair, they don’t ‘see-through’ anything at all. A thermal imaging camera detects the surface temperature of the first object in its line of sight; point one at a wall or other solid surface, and it will register the heat being radiated outward by that surface.
Because most buildings are engineered and insulated to trap heat, exterior thermographic imaging seldom reveals much about what’s going on inside and vice versa. There are some caveats here: an IR camera can be used to detect extreme heat radiating from behind a wall (such as in the case of a house fire), because the wall itself would quickly heat up too.
Similarly, some thermal cameras are sensitive enough (up to +/- 0.01 Celsius) to register the warmth given off by a person, for instance, standing against the opposite side of a sufficiently thin (and cold!) wall - but only if they remain in place long enough for their own body heat to partially transfer through the materials of the wall in that spot.
Uses of thermal imaging cameras
Beyond basic engineering applications, the emergency services are among the more familiar users of thermal detection cameras today.
The technology is deployed regularly in scenarios including firefighting, night-time police pursuits, and disaster response search and rescue, and more recently Paranormal Investigating.
thermal imaging cameras
It’s not an absolutely hard and fast rule; certain infrared frequencies can pass through glass, and certain types and configurations of glass may allow varying degrees of infrared to pass through.
Car windscreens tend to yield better results than standard household glazing, for example.
In most cases though, the image will be largely obscured by infrared reflection from the ‘wrong’ side of the glass, overlaid in varying degrees of opacity.
At the very least, the object being viewed will lack significant detail and contrast.
In short, you won’t want to be using a thermal imaging camera to get accurate readings through glass (or various other types of highly reflective surfaces).
However, there are a number of other widespread uses of thermal imaging cameras today that may be less obvious.
In this section, we’ll look briefly at some of the more common scenarios.
PRIVATE PARANORMAL INVESTIGATORS
GHOST INVESTIGATION TEAM
It's not the first we have used military technology in the paranormal investigation community.
With so many varieties, designs and sensitivities of thermal imaging cameras available, it’s important to know exactly what it is you’re shopping for before deciding on a specific product or accessories. Key considerations that will influence your ideal purchase include:
Size and weight
Ergonomics and design
Military application of FLIR technology using "Normal Mode".
You must know about and understand reflection and deflection when using Thermal Imagining detection equipment as you will catch more false-positive images of what is not paranormal, than positive images of the paranormal.
This makes using a TIC a great debunking tool, rather than capturing the apparition of a paranormal spirit.
|Thermal cameras for drones||Thermal imaging is often used in remotely piloted drones (UAVs), greatly enhancing general recon capabilities in dangerous or difficult-to-observe conditions. In hobbyist drones, thermal imaging can be a great asset to photographers for a wide range of purposes, while UAV thermal imaging is also highly beneficial to emergency response units, search and rescue teams, and in tactical military applications|
|Thermal imaging cameras for fire detection||Thermal imaging not only helps firefighters to locate survivors in low-visibility conditions where dust, fog, ash, and other contaminants occlude visibility - it can also help detect hotspots, further potential sources of ignition, or indicate the presence of still-burning fires which may be originating from unexpected locations (such as underground or within cavity walls, for example).|
|Thermal imaging cameras for Apple & Android devices||There are a plethora of ‘thermal’ and ‘infrared’ photo apps available for Apple iOS and Android phones these days. However, they’re pretty much all just simulations; standalone apps don’t really do much besides putting a fancy filter on your phone camera, effectively mimicking the overall look of thermal detection imaging.|
For a real experience of thermal imaging on a smartphone, you’ll need to buy an auxiliary thermal camera device that can be attached to the handset and used in conjunction with a dedicated app for the hardware. Good quality versions are sold in the UK and beyond by brands including Flir.
They’re not cheap by most mobile accessory standards - but until iPhones start shipping with a dedicated true IR camera, these third-party add-ons are currently the only way to perform genuine heat detection with a smartphone.
|Thermal imaging cameras for wildlife|
Wildlife photography, animal tracking and environmental monitoring are all common uses of thermal imaging technology today. IR cameras equipped with smart sensors can be set up and left unmanned in natural habitats, triggering automatically in the presence of nocturnal or otherwise hard-to-spot wildlife. This enables far more comprehensive monitoring of species and behaviours in some regions than has previously been possible.
|Thermal imaging marine cameras||There are some very important marine applications of thermal imaging, not least as a significant boost to collision detection systems when sailing at night, in fog, or during severe weather. |
While underwater thermal imaging per se is rather limited in its effectiveness (even with the most advanced technologies) as previously discussed, it’s not unusual today to find heat detection cameras manufactured to marine grade specifications and mounted in multiple positions aboard seagoing vessels of all sizes.
|Thermal security cameras||Almost all business premises today deploy security camera technologies in one form or another. In recent years, it has become increasingly standard practice to rely on thermal imaging surveillance equipment for the best possible results in terms of protection, identification, and return on investment.|
Thermal security cameras reliably perform very well in low light and poor visibility areas, as well as providing the ability to strip away much of the visual camouflage - such as dense foliage - that’s often found close to offices and warehousing. In addition, thermal imaging CCTV cameras are usually bundled with smart sensors and advanced analytics technology, helping to reduce the number of false alarms.
Finally, heat detection-based systems are often cheaper to install and run long-term than standard CCTV setups, which need to be placed along every available line of sight in order to be fully effective - and which frequently require costly additional lighting to be rigged nearby in order to provide even basic functionality.
|Night vision cameras||Although both thermal imaging IR cameras and standard ‘night vision’ units can be used to increase visibility in low light or otherwise occluded conditions, they’re actually two distinct products that rely on different technologies.|
The key difference is those night vision cameras, of the type seen in dozens of films (usually characterised by a grainy green-and-white night-time display), rely on there being just the right amount of ambient light present to amplify what little it detects. For obvious reasons, the sensor can’t cope with too much light - but many people don’t realise that in a completely dark environment, night vision technologies can’t outperform a human eye either.
Many night vision cameras are therefore equipped with an additional infrared illumination function, in order to provide a greater wavelength of amplifiable electromagnetic signals to help the sensor out in very murky conditions. These are invisible to the naked eye, but can easily be detected by anyone else using night vision; not a problem in many applications, but far from ideal in many military or surveillance uses.
While night vision often provides a more naturalistic image in the right conditions, it’s also significantly less effective than thermal imaging in revealing targets obscured by fog, smoke, dust, or camouflage.
|Industrial infrared cameras||Many current thermal imaging cameras are certified specifically for industrial use, with various different configurations and manufacturing standards available on the UK market to suit a range of particularly challenging applications and environments.|
Examples include cameras certified for use in areas subject to explosive gasses (e.g. the petrochemical industry); in below-ground applications such as mining; or around high volumes of airborne dust particles found in industries like sugar production and grain-handling.
If you’re likely to need a specific certification for your industrial infrared camera use, always check with suppliers and consult manufacturing guidelines to confirm that all relevant standards - such as ATEX and IECEx approval for safe use in Zone 1 explosive atmospheres - have been met.