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Infrared

Infrared cameras detect light frequencies beyond the visible spectrum, capturing heat signatures and objects that standard cameras and the human eye cannot see. This technology is widely used in surveillance systems to identify people and objects even when they attempt to conceal themselves.

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About this video

Infrared light occupies the portion of the electromagnetic spectrum just below visible red light, sitting outside the range that human eyes can perceive. On the opposite end of the visible spectrum, ultraviolet light extends beyond violet in the same way — both represent frequencies our vision cannot detect, but that technology can capture and interpret. The prefix "infra" means below, which reflects infrared's position beneath the red boundary of visible light. Specialized infrared cameras detect this invisible light by capturing heat signatures, rendering warm objects — including people — as clearly visible against cooler backgrounds. This capability makes infrared imaging a powerful tool for surveillance and security applications, since concealing a body's natural heat output requires purpose-built materials that are not readily available. A simple demonstration of infrared light in everyday life is a television remote control, whose signal is invisible to the human eye but appears as a flashing light when viewed through a standard camera sensor, which happens to be partially sensitive to infrared frequencies. Dedicated infrared cameras take this further by filtering exclusively for heat-based signatures, producing imagery that makes individuals easy to identify regardless of lighting conditions or attempts at visual concealment. For security and surveillance professionals, understanding how infrared systems work — and their inherent limitations, such as the possibility of heat-blocking countermeasures — is essential to deploying them effectively within a broader sensing and monitoring strategy.

What you'll learn

Explain how infrared radiation differs from visible light and describe how infrared cameras detect heat signatures for surveillance applications

What's covered

Infrared Surveillance Systems

What Is Infrared
- Below Visible Red
- Beyond Normal Sight
- Part of Wave Spectrum
Visible Light Spectrum
- Red to Blue Range
- Ultraviolet Beyond Violet
- Infrared Below Red
Infrared Camera Types
- Standard Cameras
  - Can Detect Some IR
- Specialized IR Cameras
  - Capture Heat Signatures
Practical Applications
- Remote Control Example
- Detecting People by Heat
- Hiding from IR Difficult

Key terms

Incident Response: A structured process for identifying, containing, eradicating, and recovering from security incidents.
Visible Light Spectrum: The range of electromagnetic wavelengths perceivable by the human eye, spanning from red on the lower end to violet on the upper end.
Heat Signature: The infrared radiation emitted by a person or object due to its temperature, detectable by infrared cameras for identification and surveillance.
Infrared Camera: A specialized imaging device that detects infrared radiation rather than visible light, producing images based on heat signatures emitted by objects or individuals.

Topics

Infrared Thermal Imaging Surveillance Heat Signatures Electromagnetic Spectrum Physical Security

Transcript

Another great way for surveillance and sensing things is some sort of infrared system. Infrared is able to see and pick up things that normal cameras are not able to pick up, so we can easily identify certain objects.

Where infrared sits in the spectrum

When it comes to waves going through the air, we have a certain range that are radio frequencies. We also have visible light. But we have something that's called infrared. On one side of the visible light spectrum we have red; on the other side we have blue. If you go past blue you get into violet, and then ultraviolet. Ultraviolet is beyond violet, so it's beyond our visible sight. Same thing if we go below our visible range: we go from red to infrared. Infrared means below, so we're below the red frequency. And that is where we can still pick up some of this through specialized cameras, through infrared cameras, but normal cameras can't pick that up and our eyes can't pick that up.

Examples

One example of infrared is going to be on a remote control. What I can see here is, through the camera I can see that flashing light, but if I look at it like this, I can't see that. So that's an example: it's below the visible light spectrum, so my eyes can't pick it up, but the camera can pick that up. And this is not actually a special camera — it just picks up that infrared.

But there are specialized cameras that just pick up infrared, and this is what those look like. Essentially what this is is it's showing you the heat signatures, so we can see the people. It makes it really hard for somebody to actually hide with this, right? Because how do you hide your heat signature? You'll have to get some sort of special material in order to hide from that perspective. So that's an example of an infrared camera.

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