What Exactly Can Thermal Cameras “See” Through? Addressing Common FAQs

 

What Exactly Can Thermal Cameras "See" Through? Addressing Common FAQs

Short-wave infrared (SWIR), midwave infrared (MWIR), and longwave infrared (LWIR) refer to distinct segments of the electromagnetic spectrum, particularly within the realm of infrared (IR) radiation. Each of these terms denotes a specific range of wavelengths within the IR spectrum, and they find widespread applications in diverse fields such as remote sensing, thermal imaging, and spectroscopy.

Selecting between SWIR, MWIR, and LWIR hinges on factors like the application, budget, atmospheric conditions, and desired features such as image quality and temperature sensitivity. Each infrared spectrum region has unique strengths and limitations, catering to varied scenarios. Explore the distinctions and commonalities among SWIR, MWIR, and LWIR, along with a specific use case for each.

Differences Between SWIR, MWIR and LWIR

SWIR, MWIR, and LWIR represent segments of the infrared spectrum, each possessing unique features, applications, and technologies. Specifically, SWIR encompasses shorter wavelengths, typically spanning from around 1,000 nanometers (nm) to 3,000 nm or 1 to 3 micrometers (μm). SWIR is commonly employed in material identification, moisture detection, and specific medical imaging techniques through imaging and spectroscopy.

MWIR covers wavelengths from approximately 3,000 nm to 8,000 nm, equivalent to 3 to 8 μm. This range of radiation is frequently applied in thermal imaging to detect variations in heat and finds utility in tasks such as missile detection and imaging through atmospheric haze.

LWIR encompasses extended wavelengths, typically spanning from approximately 7,500 nm to 15,000 nm, or 7.5 to 15 μm. LWIR radiation is commonly utilized in thermal imaging and thermography, specifically for detecting the naturally emitted heat from objects. This range proves valuable in applications such as night vision, temperature measurement, and thermal analysis.

SWIR cameras tend to have higher costs attributed to the utilization of specialized materials and technologies. In contrast, MWIR and LWIR technologies have become increasingly accessible over time, resulting in a broader range of cost options.

Media often spreads misinformation about thermal, or infrared, imaging. What surfaces can thermal cameras effectively penetrate? Here, we'll delve into frequently asked questions about what thermal cameras can or cannot reveal, although technically, they detect heat and represent it with colors based on temperature ranges.

Can Thermal Imaging See Through Walls?

Thermal cameras, contrary to cinematic portrayals, are unable to see through walls. Typically, the thickness and insulation of walls prevent the penetration of infrared radiation. When directed at a wall, a thermal camera captures the heat emitted by the wall itself, not the objects behind it. Nevertheless, if there is a significant temperature difference caused by something within the wall, a thermal imager can detect it on the wall's surface. This capability is often utilized by building maintenance professionals to identify problems such as water leaks or inadequate insulation without resorting to tearing down walls for assessment.

Camera Captures the Heat

The studs within the wall, forming vertical lines, exhibit a lower temperature compared to the insulation, creating a temperature contrast on the wall's surface.

Can Thermal Imaging See Through Smoke?

Indeed, thermal cameras have the capability to identify heat through smoke, making them extensively utilized by firefighters. The presence of soot particles in smoke acts as an effective barrier against visible light while enabling the passage of infrared radiation. This feature aids firefighters and other first responders in navigating through environments filled with smoke.

Thermal Imaging Through Smoke

 The individual standing in the doorway remains hidden from view due to smoke in the visible light range yet is readily identifiable through thermal imaging

Can Thermal Imaging See Through Fog?

Fog and rain can significantly reduce the effectiveness of thermal cameras by causing radiation to scatter off water droplets, thereby limiting their range. Nevertheless, thermal cameras often outperform visible light cameras and the human eye in penetrating fog under various conditions. This capability is a key factor prompting car manufacturers to integrate thermal imagers into the sensor arrays of autonomous vehicles.

Object Detection

In specific situations, thermal imaging has the ability to detect objects through fog with greater clarity compared to visible light detectors.

Can Thermal Imaging See Through Glass?

Interesting fact: Glass functions akin to a mirror for infrared radiation. When you aim a thermal imager at a window, you won't observe anything beyond the glass, but you'll witness a clear thermal reflection of yourself. This occurs because glass, being highly reflective, showcases the reflected temperatures of objects rather than allowing the transmission of infrared radiation through it. Similar principles apply to other reflective surfaces, such as polished metal.

Digital Camera and Thermal Camera Detection

The digital camera captures the view of the trees outside through the glass, whereas the thermal camera detects the heat reflection of the photographer.

Can Thermal Imaging See Through Concrete?

The response to this query is essentially similar to that for walls—no, but a thermal camera could potentially identify elements within the concrete, such as pipes or radiant heating, causing temperature variations on the concrete surface.

Thermal Imaging Detect Through Concrete

Radiant underfloor heating is distinctly noticeable beneath a concrete floor.

Can Thermal Imaging See Through Metal?

Metal presents challenges in the field of thermography. Shiny metal, characterized by smooth or polished surfaces, behaves like an infrared mirror by reflecting infrared radiation, much like glass. This reflection can pose challenges for those attempting to monitor pipes or machinery for signs of overheating components. On the other hand, oxidized metal or metal coated with a matte material is more conducive to accurate measurements (refer to our article "Using Low-Cost Materials to Increase Target Emissivity" for further insights). It's important to note that thermal cameras cannot penetrate through metal objects, although conductive metals may reveal hot spots, cold spots, or provide insights into the level of a substance within a metal container.

Thermal Imaging Detect Through Metal

Observing the infrared images makes it evident how much the tanks are filled, as the temperature contrast on the metal surface is a result of the liquid contained within

Can Thermal Imaging See Through Trees?

While a thermal camera cannot penetrate the trunk of a tree to detect objects, it proves valuable in identifying people or animals within forested regions. Search and rescue teams frequently utilize thermal imaging to locate heat signatures when navigating extensive wilderness areas.

Thermal Imaging Detect through Trees

Thermal imaging lacks the capability to penetrate through trees or wood, yet it proves advantageous in detecting individuals within forested areas, where their heat signatures are more conspicuous compared to what a visible image might reveal.

Can Thermal Imaging See Through Plastic?

An entertaining party demonstration with a thermal camera involves holding up a thin, opaque sheet of plastic, such as a garbage bag, in front of a warm object or person. In this scenario, infrared radiation can pass through the plastic, enabling the thermal camera to detect what lies behind it, while visible light remains blocked. It's worth noting that this trick is effective only with very thin plastic; thicker plastics will impede the passage of infrared radiation.

Thermal Imaging detect through plastic

The plastic bag predominantly obstructs visible light, yet it allows the transmission of infrared radiation.

Can Thermal Imaging See In The Dark?

 The answer is yes! Thermal imaging remains unaffected by darkness as it doesn't rely on visible light to visualize heat.

Thermal Imaging In The Dark

Comparing CCTV footage with thermal imaging highlights that thermal imaging doesn't depend on visible light to create an image.

What are your plans for utilizing a thermal camera? View our range of thermal cameras or contact us to find out further.

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