Thermal imaging cameras have been widely used in many industries for decades: soldiers find targets through thermal sights, police set them on helicopters to search for people, and builders use sensors to find sources of cold air leaking into houses. To identify temperature deviations from surrounding things, today it is enough to purchase thermal imagers for smartphones or tablets in the form of a prefix.
Handyman
Perhaps hunting for Arnold Schwarzenegger in the classic 1987 film Predator is not your thing. But today there are enough application methods for the thermal imager - to find a missing cat hiding in the dark under the porch, diagnose a pipe block in the bathroom, or see how much propane is left in the gas grill tank. These cameras allow you to see previously invisible thermal landscape, revealing amazing worlds around us.
There are also limitations. For example, glass transmits visible light well, but filters infrared radiation, which we call heat. This makes the windows virtually opaque to thermal imagers. The device can show the surface temperature of the glass, but if someone stands behind the window without touching it, this person will remain practically invisible, although thermal reflection in the glass can be seen. That is why thermal camera lenses are not made of ordinary glass; they require special materials, such as germanium, which transmit light in the infrared range.
Their resolution is much lower than that of conventional multi-megapixel cameras built into smartphones today. Images are blurry and video speed is slow. But with all this, the sensations of a person who looks into complete darkness and sees a lively thermal landscape are simply indescribable.
Flir One vs Seek Thermal
If you look for a thermal imager for a smartphone on Google, then there are not many manufacturers. They can be counted on the fingers of one hand. Even a Chinese thermal imager for a smartphone is a rarity. Among this handful of manufacturers, the most famous are Seek Thermal and Flir Systems. Their cameras can be connected to the phone jack. Seek has an advantage in size: the thermal imager for an Android smartphone is smaller than a 9-volt battery, and the Flir One is slightly wider than the iPhone 5S and almost twice as thick. Both devices are protected against damage when carried in a bag, but Seek is also waterproof and looks much more durable.
The thermal imager for the Seek Thermal smartphone does not have a power switch, battery or charging port. Thanks to this, the design of the camera is very elegant, simple, without any additional cables or chargers. But it puts a serious strain on the phone’s battery. Flir has a different approach, with an internal battery that needs to be charged using the included mini USB cable. The battery lasts for an hour of continuous use.
Another difference that ultimately makes FLIR the best choice for most people is that it has two cameras - a traditional one with VGA resolution and thermal. In real time, the image on the phone is composed of two channels. At the same time, high-contrast contours of the full-color camera provide the necessary clarity of temperature clots. This is especially necessary when you need to return to images later. Otherwise, it is difficult to understand what exactly is captured in the picture.
Both cameras are available for devices using the Lightning interface and for Android devices with a micro-USB connector.
In shape, the thermal imager for smartphone and tablet Seek Thermal is a prefix, and FLIR ONE is made in the form of a bumper for the iPhone. Despite the various form factors, the device combines high build quality, stable performance and user-friendly design.
FLIR ONE: thermal imager for smartphones. Description
In the first generation, the FLIR ONE VGA camera for the visible spectrum and the Lepton long-wave infrared sensor were combined in the form of neat removable “skids” that can be pulled out if necessary. The bumper remained on the iPhone all the time, and the “slide” was disconnected for charging via micro-USB. In models for iOS and Android, such a decision was abandoned in favor of a separate console.
Unlike the Seek, which is powered by the phone, ONE has a built-in battery. It should be noted that ONE FLIR does not act as an external battery pack for the iPhone, all energy is consumed by the temperature sensor and camera.
Such a solution a little “complements” the slim profile of the iPhone 5s. The convex shape and cut-out for the lens and flash visually make the soft polycarbonate construction more than it actually is.
In addition to the two logos, the no-frills design matches the design of the rest of the company's high-quality products. A micro-USB port, a charging status indicator, and a headphone cutout are located at the bottom, while the thermal imager, mode switch, and lens cap are located on the back. A multi-color LED is mounted directly above the cameras to signal power status and successfully calibrate.
The thin bumper has cutouts for accessing the volume and mute keys, the rear lens and Lighting port, speaker, headphone jacks, microphone jacks, and even the Apple logo.
Seek Thermal: a thermal imager for smartphones. Specifications
The size of the Seek does not exceed that of the thumb and, when connected, adds 2.5 cm to the total height of the phone. The thickness of the device is sufficient so as not to go too far beyond the profile of the smartphone.
The Seek's magnesium body is almost weightless, but it will take time to get used to the extra “chin.” Since the Lightning iPhone or Android micro-USB connector is the only point of contact with the phone, the thin metal protrusion carries the function of supporting the entire structure, that is, the module can simply fall in a collision.
Externally, the thermal imager for a smartphone and tablet is attractive, small in size with concentric circles around the lens made of chalcogenide lenses, a material commonly used in photonics. On traditional lenses, these ridges deflect reflected light, but here they are larger for appearance.
The kit includes a sturdy case filled with dense protective rubber with a recess under the device for reliable protection during transportation.
MSX Technology
Thermal imagers for smartphones FLIR and Seek use completely different hardware and software.
As mentioned above, FLIR uses two specialized sensors to output hybrid thermal images. Marketed under the name MSX, the system combines the VGA camera’s visual information and temperature data captured by FLIR’s 80x60 Lepton sensor. This approach gives impressive results that give a clear shape to blurred heat spots.
In practice, the dual sensor is calibrated so that there is no need to constantly adjust the parallax if the objects are at a sufficient distance from the phone (more than one meter).
At the same time, MSX mixing is imperceptible, but at close distances, parallax is becoming an increasingly important problem. To compensate for this, you need to use the FLIR ONE Closeup application, which allows users to manually adjust the horizontal merge points of the MSX. The program works in standard color modes, but it lacks the finer settings offered by the main FLIR program, such as setting emissivity coefficients to adjust the ability of a material to radiate thermal energy.
Useful tools
The image response is instant - the delay is felt only when panning. Photo processing is just as fast. Video recording starts immediately, and the image adjustment tools provided by FLIR ONE are high-end. Of these, the most useful is a point meter, which can decrypt the value of the thermal signature in the form of the thermometer readings of any selected point.
There is one inconvenient aspect of the FLIR ONE design - it's a self-calibration mechanism. From time to time, the app requires you to slide the switch located just below the dual lens. Since the finger, as a rule, is already in the right position, this is not difficult to do, but the program asks you to perform this procedure constantly. Switching makes the whole phone move, which spoils the video quality.
Calibration resets the sensor, not the MSX-parallax, so performing this setup operation is not so necessary for image quality. For accurate readings, however, periodic adjustment is necessary.
Reliable FLIR ONE Software
FLIR, with its rich history of military and professional thermal imaging solutions, has provided its hardware with reliable programs that allow various operating modes, temperature display methods and much more. Unfortunately, many features are distributed between different applications, which is not very convenient.
It is clear that some functions may not be needed by users - professionals do not need a thermal panorama, but many files clutter up the screen and require constant switching between programs to find the right tool. Consolidation is a must.
As for the applications themselves, FLIR ONE Paint, for example, allows you to paint a regular photo with thermal readings. The program splits the MSX photo data into two different images, which can then be mixed manually.
FLIR ONE Timelapse is another useful tool that allows you to take pictures at intervals of several seconds or minutes and play them in video mode.
True temperature sensor
The thermal imager for Android smartphones Seek uses a "true thermal sensor", or a vanadium oxide microbolometer capable of detecting long-wave infrared radiation in the range from 7.2 to 13 microns. According to the technical specification, the sensor has a total of 32,136 thermal pixels on an array measuring 206 by 156 pixels.
Thermal imagers for Seek and FLIR smartphones use completely different sensors. Since the first relies solely on the temperature sensor, its output image is spherical and fuzzy. Without sharp edges and contrasting tones, like the two-lens FLIR, Seek shots are deceptively blurred. With a higher pixel count, True Thermal Sensor captures much more information than Lepton FLIR.
Another area in which Seek is superior to FLIR is the detectable temperature range –40 ° C to 330 ° C, and tests confirm this. The maximum that FLIR ONE is capable of is 100 ° C. When measuring temperatures well above 330 ° Seek software crashes and starts to show values of tens of thousands of degrees. But this is most likely some minor mistake.
Instead of constantly manually reconfiguring the temperature sensor, Seek performs this task automatically when the camera temperature changes. The operation of the electromechanical shutter is accompanied by a slight click, but its audibility is minimal.
Seek offers 3 levels of IR sensitivity, detection, recognition and identification for distances of 300, 75 and 45 m. A 36 ° field of view is inconvenient when shooting close up. You can use digital zoom, but the quality decreases so much that it is practically impossible to use.
Rich opportunities
The only Seek app is well debugged, with many great features that will satisfy both professionals and amateurs. Along with several viewing modes - color, white, black, etc. - the program displays the maximum and minimum temperatures, which is very useful when searching for objects in the dark. A threshold mode is also available for detecting thermal signatures above a certain level, which is useful when used in hot environments such as the engine compartment of a car.
Thermal + is similar to the FLIR Paint application and superimposes temperature data on top of a normal shot. Unfortunately, this feature uses a camera that is 12 cm at the opposite end of the phone. Parallax is not calculated exactly, as a result of which the image does not fit correctly.
Pros and cons
At $ 250, the thermal imager for an Android-based smartphone FLIR ONE may cost more than the phone to which it is attached, but for some, the positional accuracy offered by MSX technology is worth it.
The price of Seek Compact is the same and the device has a higher resolution of the sensor, although the images it creates are not so perfect.
FLIR ONE is a thermal imager for a smartphone, the user reviews of which are most favorable. Consumers are thrilled with the MSX overlay detailing the image, their own battery and powerful visualization software.
Among the shortcomings are the need for periodic sensor calibration, iPhone 5 / 5s-specific bumper model design, and software broken into separate components.
The positive quality of Seek Thermal is the presence of a fast self-calibrating sensor, and the negative - a narrow field of view and a small detail of the image.
In terms of overall quality, FLIR ONE is on par with its competitor, but lags behind when it comes to thermal radiation recognition . But the lack of sensitivity of the Lepton sensor is compensated by the superposition of a VGA camera on the image, which allows for incredible detail. FLIR ONE snapshots look amazing and the software is robust, albeit fragmented. Nevertheless, whatever thermal imagers for smartphones would be chosen, any of them will allow you to look at a world never before seen, despite the fact that it was always before our eyes.