Understanding IR Technology

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Thermal ID

Seeing Thermal ID Markers From Far Away

Why take this lesson?

We are often asked,  “How far away can I see a thermal ID marker ?”

While this is actually a complicated question,  let me breakdown it for you to help you understand.

You will learn:

  • Major factors which affect detection in a thermal imager
  • Steps to Determine Distance Calculations:
  • Steps to Determine Size Calculations:

Ok, let’s get started!

First, keep in mind that thermal imagers DO NOT amplify energy while night vision goggles DO amplify energy.  Because of this amplification a small night vision combat ID marker will appear larger than it really is.

Second, there are numerous major factors which affect detection in a thermal imager.

  • Distance: How far away is the target
  • IFOV: Basically the optics
  • Resolution: How many pixels in the thermal imager’s sensor
  • Display: If a human is looking at a screen, that resolution and their eyes effect detection.
  • Object size
  • Emissivity of the marker: The quality of the marker

You can access a SPREADSHEET that allows you understand how the first four items relate.

Steps to Determine Distance Calculations:

  1. Input the object size
  2. Input the IFOV and resolution from your thermal imager’s user’s manual.
  3. Determine how many pixels on the screen will need to be covered for the human to detect the combat ID marker
  4. The result will be the distance at which you can detect the object.

Steps to Determine Size Calculations:

  1. Input the distance to the object
  2. Input the IFOV and resolution from your thermal imager’s user’s manual.
  3. Determine how many pixels on the screen will need to be covered for the human to detect the combat ID marker
  4. The result will be the size of combat ID marker you could detect.

If the emissivity of the combat ID marker is insufficient, it will not appear distinct from the ambient environment and will not be detectable.

Finally, detection and identification are different.  You can detect something without being able to identify it.  In order to differentiate in the spreadsheet, change the pixels requirement.  Generally, the pixels to detect will be less than the pixels required to identify.

If you have questions, contact us and we will help.