Like most geeks in my generation, my first real glimpse of thermal imaging was provided by John McTiernan’s 1987 film Predator, where Arnold Schwarzenegger and his team of badasses are stalked and killed by an even badassier three-meter-tall alien out on safari. The eponymous "predator" perceives the world through machine-augmented infrared vision, and Ahnold’s body heat is brightly visible to the creature as he and his crew scurry around amidst the comparatively cool jungle foliage.

It makes for a neat visual effect, and Ahnold must figure out how to evade the hunter’s thermal vision as the movie violently explodes toward the inevitable final showdown. But real-time infrared thermal imaging is expensive—McTiernan had a Hollywood budget and could afford to rent the bulky equipment required to capture the film’s iconic imagery. Thermal imaging is still most often seen as a tool of military and law enforcement, with even small hand-held thermal cameras costing thousands of dollars.

FLIR Systems wants to change that. The Oregon-based company is the largest manufacturer of thermal imaging systems in the world, and it has a substantial customer base in the United States Department of Defense (the company’s name comes from the acronym FLIR, which stands for forward looking infrared). The company also makes medical grade thermal imaging devices and even professional-level thermal cameras intended for use by civilian agencies (like local fire departments). But FLIR Systems’ newest product is aimed at normal folks who don’t necessarily have thousands of dollars to spend on a pro-grade thermal imaging system.

The FLIR One is a $349 iPhone accessory. It’s a self-contained device with its own standard camera, infrared-based thermal imaging camera, its own SoC, and its own battery. It relies on an attached iPhone solely as a display and as a means to store and share images and video. FLIR Systems sent us one, and we’ve been spending the past few days wandering around, looking at things in a whole new light—and, sometimes, looking at them without any light at all.

Lee Hutchinson

Lee Hutchinson



Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

It’s an unquestionably cool gizmo—Predator vision in your pocket!—and producing the device in public quickly draws a crowd of people eager to see what they look like in infrared. But is being able to see heat useful enough to justify the $349 price?

Stick around and let’s find out.

Geez, you got a small sensor

Specs at a glance: FLIR One Visible light camera VGA (640 × 480), used for MSX blending only IR sensor FLIR "Lepton" LWIR (long wave infrared) Wavelength sensitivity 8-14 ?m Temperature sense range 0-100 degrees Celsius Thermal variance detection 0.1 degrees Celsius Onboard battery 1400mAh (~2 hours of continuous use) Ports MicroUSB (charge only) Size 140 mm × 61 mm × 22 mm Weight 110 g Supported smartphones iPhone 5 and 5S only Price $349

The core component that makes the iPhone-sized FLIR One work is FLIR’s Lepton long-wave infrared sensor. The imaging device is smaller than a dime (it measures 10.6mm by 10.6mm, with a height of 5.9mm), and it produces a relatively low-resolution 80x60 thermal image. It’s also uses very little power, unlike its larger brethren, with a nominal power draw of 150mW.

The Lepton sensor detects infrared in the "long wavelength" region, between 8 and 14 ?m, which means it’s best suited for detecting infrared radiation from things in a normal human-comfortable range of temperatures (FLIR tells Ars that the FLIR One can best see objects that range in surface temperature from 0 to 100 degrees Celsius). Within its detection range, the Lepton sensor can differentiate temperature variances as small as 100 millikelvins, or 0.1 degrees Celsius. It’s got a maximum rated range of about 30 meters (about 100 feet)—unlike military systems, which work at distances of many miles.

For all the sensor’s sensitivity to deltas, its resolution of 80x60 makes it seem like like FLIR doesn’t have the Lepton pushing too many pixels. But the FLIR One has a trick up its sleeve: the second camera. If there’s sufficient light, the FLIR One combines the output of the Lepton thermal sensor with the VGA-resolution output of its standard visual-light camera using a method the company calls "MSX blending" (the "MS" stands for "multi-spectral"). The device algorithmically detects edges in the visual image and overlays them on top of the sensor’s thermograph, resulting in a much sharper picture with well-defined details.

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Of course, this only works in situations where there’s enough light for the standard camera to see—it’s also possible to use the FLIR One in complete darkness. When doing so, you lose the extra detail provided by the image blending, but the 80x60 thermograph is still quite easy to interpret if you have some idea of where you are and what you’re looking at.

If it radiates, we can see it

Guys, I am not going to lie and tell you that I didn’t walk around my house with the FLIR One in hand making predator clicky-noises and whispering "turn around" and "over here," because I did. The FLIR One turns familiar surroundings into amazing unexplored landscapes—I spent almost twenty minutes just splashing hot and cold water around in the kitchen sink, watching the heat and cold radiate out across the stainless steel.

Just screwing around with the FLIR One feels a lot like you’ve found a cheat code in a game, except in this case the game is real life. Want to see where your hot water pipes are inside your home’s walls? Turn on the faucet and look. Want to see which bread at the bakery is freshest or which beer in the cooler is coolest? Just look. Curious if there’s a bunny hiding in your bushes in the back yard? Just look.

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

It even grants you some limited superhuman powers—though not as many as you might think. Here we can point the finger squarely at movies that use thermal imaging as a wall-hacking magical tool for setting our expectations just a bit too high. Drywall and other common building materials are opaque to infrared—they absorb and radiate their own heat, but you cannot use the FLIR One to see though walls like Robocop (though you can see the outlines of particularly warm localized heat sources, like hot water pipes, if they’re hot enough and close enough to the drywall). I also couldn’t find a keypad that I could lift a number sequence off of Splinter Cell-style, no matter what material the buttons were made of.

You can see footprints, though not on all materials. I found it very easy to catch sight of my tracks while walking around on carpet, which retained visible traces of my feets’ heat for nearly a full minute. Tracks on tile, on the other hand, barely registered and were gone after a second or two. And, obviously, wearing shoes cloaked my footfalls entirely.

There are more serious use cases that suggest themselves beyond just pointing at stuff and going "wow, cool!" The FLIR One makes it practical to get an assessment of where your home might be leaking heat during the winter or cool during the summer. A quick glance around various rooms in Casa Hutchinson showed that as good a job as our builders did, there are hot spots in every single room, almost always in the corners—likely because corners are harder to jam insulation into. It’s also pretty darn obvious that while my double-paned windows are doing a great job at keeping the inside and outside thermally separate, my doors are leaking huge amounts of precious cool air out into the Texas summer.

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Long tall Sally

The FLIR One package includes an iPhone 5-sized shell that snaps around your phone, and then the FLIR One itself, which clamps onto the back of the shell and plugs into the iPhone via the Lightning jack at the bottom. When attached to the phone, the FLIR One extends about a centimeter below the phone’s bottom, and it includes a hole through which you can plug in your headphones to the iPhone’s headphone jack (with the aid of an included adapter to bridge the gap).

With the FLIR One in place, you can’t plug your iPhone into your computer—the FLIR One has a microUSB port at the bottom for charging its own 1400mAh battery (which lasts for about two hours of continuous use), but your iPhone’s Lightning jack is occupied by the FLIR One itself.

On its back, the FLIR One has a cutout at the top for the phone’s built-in camera, and a central chrome-ringed circle inside of which rests its own tandem camera arrangement. Below this is a three-position switch. The top position puts the FLIR One in standby and closes protective shutters over the cameras; the middle position wakes the Flir ONE from standby; and the bottom position is used to "tune" the FLIR One.

In use, I found myself being prompted to "tune" the FLIR One every few minutes. The app tells you the device needs "tuning" by showing you an image of the rear switch; to "tune," you hold the switch in its bottom position until the app displays a check-mark, and then you release the switch.

The FLIR folks explained that "tuning" the FLIR One is like adjusting the white balance on a camera. If you shift the scene in front of the Flir ONE a lot—like I was doing as I walked around my house and yard, eagerly peering at everything—the sensor needs to be "tuned" again in order to properly measure temperatures. It takes a few seconds, but you won’t have to bother with it unless you’re looking at lots of different things one after the other. If the FLIR One is being held relatively stationary, you won’t have to re-tune.

Lee Hutchinson



Lee Hutchinson

Lee Hutchinson

Lee Hutchinson

Changing colors (like the chameleon)

The primary way to interact with the FLIR One is with its iOS app. The app lets you view the live output from the FLIR One’s Lepton sensor, automatically blended with the visible light camera if there’s enough light for it to operate. You can capture still images or movies, and also use reticle in the center of the app’s viewport to spot-check surface temperatures.

Infrared-based thermal imaging is colorless, of course, because what our brains interpret as an object’s "color" is a function of the wavelengths of light the object emits or reflects. Red is at the "bottom" end of the visual light spectrum (remember ROY G BIV?), and as an object’s emissions lengthen past what we can see, the object’s color fades from red to black—this is easy to see if you watch a red-hot piece of metal cool. Because we can’t perceive colors with long wavelengths, thermographic images are always presented in false color.

Many military infrared systems use black and white to show temperature variances, allowing the user to select which represents higher and lower temperatures (it might be useful in some circumstances to see hot temperatures in white against a black background, or in black against a white background, depending on the environment and ambient infrared noise). The FLIR One’s app comes with seven different false color schemes, including a military-style white-on-black. Which one you use is personal preference, though after fiddling them I found the default to be the most useful.

Lee Hutchinson



Lee Hutchinson

Havin’ me some fun—but only on iPhones

At least for now, the FLIR One is compatible only with Lightning-equipped iPhones—that would be the iPhone 5 and 5S (the 5C isn’t listed as a supported device in FLIR’s technical documentation). The reasoning behind this isn’t necessarily technical, but practical: FLIR wanted to design and sell the FLIR One as a single device in a single form factor.

This, unfortunately, means that the FLIR One will be compatible only with iPhones—at least for now. The FLIR folks say that they’re looking at ways to support Android, but that would mean supporting not just another operating system but a whole slew of differing physical form factors. There are ways around this, like perhaps releasing a version with an updated enclosure that snaps into different shells on different phones, but the company made the decision with their initial release to support only a single device in a single shape.

From a software standpoint, there are a few free iOS apps available that use the FLIR One’s capabilities. FLIR seeded a beta SDK to about 20 developers prior to the FLIR One’s release, and the launch apps do a few neat tricks (there’s one that assists with taking close-up macro photos, and another to take thermographic panoramas, for example), but there are only five FLIR One-compatible apps in the iOS App Store right now. Now that the FLIR One is available, FLIR plans to release their SDK at some point in the near future, but no date has been set for its availability.

Some video clips with me and the FLIR one, showing how thermographic imaging makes even everyday ordinary stuff look amazing.

Get to the future

One thing that came up over and over again when talking with representatives from FLIR was the company’s desire to see "infrared everywhere." The analogy painted by FLIR marketing director Bruce Cumming in a phonecall to Ars was that of the global positioning system: GPS is a military creation that used to be reserved exclusively for military use. These days, though, tiny GPS receivers are located in tons of devices (I’ve even got one in my watch!). FLIR is hoping to spark a similar level of consumer adoption with thermal imaging, and the FLIR One is a step on that path.

And just as civilian GPS receivers started out with high price tags, we come back to the FLIR One’s biggest weakness: it costs $349. That is, frankly, a hell of a high price to pay for a device that—let’s be honest—most folks would use intensely for a few days and then leave sitting on a shelf after the "oooh, cool" shininess wears off.

But from FLIR’s perspective, that’s probably just fine. This isn’t a one-shot device produced by a startup with limited means—FLIR Systems is a 3,500 employee company with $1.5 billion in yearly revenue, much of which stems from Department of Defense contracts. It’s the kind of company that can invest in new product areas like the FLIR One, even if those products aren’t going to generate buckets of money.

As a sustainable, affordable, consistently useful piece of kit, the FLIR One falls short. But as a first step into a world where thermal imaging is as easy to use and accessible as a point-and-shoot camera or a hand-held GPS navigation system?

From that perspective, this is a damned interesting device. If this cost $99 instead of $349, I’d buy it in an instant. And I suspect that in a couple of years and after a few iterations, that price point is exactly where FLIR’s consumer products will be.

The Good

Dead easy to use—very much an "it just works" device

Augments reality and gives you superhuman abilities

SDK will eventually be available for developers to build apps with new functionality

3-5 times cheaper than other handheld thermal imaging systems

The Bad

No Android or Windows Phone compatibility—iPhone only

More than just "iPhone only," you must have a Lightning-equipped iPhone 5 or 5S to play.

Constant re-tuning needed if you're going to be moving around a lot

No SDK available yet, so would-be FLIR One app developers will have to wait

Limited app selection right now

The Ugly