Seeing What You Can’t See, or: How I Learned to Stop Worrying and Love Thermal Vision
Tom McHale 12.17.14
If you really want to be able to see, sometimes you have to use a lens that you can’t see through.
I recently toured one of FLIR’s manufacturing facilities and got quite the lesson on how to see things you can’t really see. While FLIR makes a wide variety of “sensing” gear, not just infrared products, they’re most commonly known for commercial and military products that help folks see things not normally visible to the human eye. By using lenses made from exotic materials like Germanium and Zinc Selenide and adding a touch of sensing and computer image-enhancement technology, FLIR products are able to present the user with a picture of the environment based on relative heat signatures, or infrared.
The hardest thing to get my head around was the fact that visible light is irrelevant to infrared imaging. You can’t see through the lenses at all, which is kind of freaky when you think about it—especially since they’re called lenses. As visible light has no effect on the infrared image, FLIR products are equally useful in daylight, darkness, and obscured-visibility conditions.
Everything has a temperature signature, even if that signature is a lack of temperature. Objects that do not “generate” heat still have a signature as they absorb and release heat based on environmental conditions. Every material reacts differently and even minute variances in material shape or thickness result in different relative heat levels. The result of all this is that a FLIR device can create a very accurate picture of your surroundings—regardless of ambient light conditions.
Unlike light-amplification technology like standard night vision, it’s difficult to camouflage an object from FLIR. One notable exception is glass. Infrared does not travel well through that medium, so objects behind glass are essentially invisible. For now.
The FLIR Scout is a great product for people who enjoy outdoor activities like hunting, camping, hiking, and critter watching. As we’ll see, it has a variety of other interesting uses. A monocular, handheld device, it offers different modes of heat map display including InstAlert options that highlight the hottest objects in bright red.
The FLIR One is a hardware and software combination that turns your iPhone into an infrared-enabled camera. The case contains a rechargeable battery and two cameras: one IR and the other optical. The software combines input from the two cameras to generate a representation of what it sees based on infrared signature and whatever it can detect optically.
Rather than talk about features, let’s take a look at some of the uses I found for these two products.
NOTE: I shot all of the FLIR Scout photographs in this article with a regular camera “through the FLIR lens” so please forgive the quality. The clarity of the images with the FLIR Scout was far better than the representations shown here.
1. Spot game
The FLIR Scout base model I tested is capable of spotting a man-sized target at distances up to 350 yards. I believe it. During my informal tinkering, I spotted the doe shown here at a distance of 80-plus yards and she was bedded down in a brushy area—completely invisible to the naked eye. This photo was taken in the dark but would have looked the same if taken in broad daylight.
The InstAlert feature of the FLIR Scout has four intensity modes. If you crank up the sensitivity, as in the photo above, you’ll see “warmer” spots on other objects besides living things. You can easily see moving animals at distances up to a couple hundred yards.
2. Measure the temperature of an object without having to touch it
Jeff doesn’t know this yet, but I’m using him as an example of how the FLIR One can remotely measure the temperature of an object in addition to generating an infrared image representation. As you can see, Jeff has warmed his shirt up to 74.9 degrees by working diligently on his laptop. I’m not implying that I treat Jeff as an object…
3. Finding your way around
I took these photos in pitch-black conditions to provide an illustration of how well you can “see” for navigation purposes. If you have to get from point A to point B in dark, hazy, or smoky condtions, you can do that with the FLIR Scout. As it’s a handheld monocular, you can keep your other eye open to assist with peripheral and short-range vision.
4. Viewing inanimate objects
FLIR devices don’t just work on living or heat-generating objects. As you can see from this photo I took with the FLIR One, inanimate objects, like my son, are clearly visible. Everything has a heat signature, even if it doesn’t generate its own.
5. Tracking game
The InstAlert feature of the FLIR Scout is great for spotting living things. If you’re tracking game after a shot, it can also be used to spot and follow blood trails, day or night. While I did not have the opportunity to use these devices on a hunt, I did test out the bodily fluid spotting capability when I let my dogs out before bedtime to “do their thing.”
6. Finding stuff
If you remember that an infrared camera sees things differently than your eyes, you can use it for all sorts of things. One shooting-related use is finding spent brass cases in the dirt, leaves or grass. Even when it’s no longer hot, brass cases have a different infrared profile than whatever they’re sitting on. Finding your brass on the ground is a piece of cake. People might look at you funny for waving your iPhone around over the ground, but hey, brass is worth real money!
7. Check the status of your campfire
You can make Smokey the Bear proud by viewing your doused campfire with a FLIR device. If there’s anything still burning down in the ashes, you’ll see it!
8. Illicit teenage car use
Got teenage kids? Suspicious about unauthorized use of the family wheels? Take a look with your FLIR to see if it’s recently been driven.
9. Who or what was there?
One of the more mind-blowing capabilities of FLIR is the ability to see into the past. When you, or an animal, steps on the ground, it changes the temperature profile of that spot for a period of time. Depending on conditions, you can see footsteps after their creator is gone. The FLIR Scout clearly shows my dog’s footsteps over leaves and pine needles for a short period of time.
10. Use your imagination
While the FLIR Scout is marketed as an outdoors device, the FLIR One is handy around the house, office, campsite or virtually anywhere else. Use it to find electrical boxes and wiring. Spot leaks in your air conditioning and heating systems. See where you might have leaks in doors and windows. Find critters or bugs in the rafters or the shed. The possibilities are endless.
Tom McHale is the author of the Insanely Practical Guides book series that guides new and experienced shooters alike in a fun, approachable, and practical way. His books are available in print and eBook format on Amazon.