When we put night vision devices on the spot, there are a lot of different scenarios, where the performance of the night vision is unquestionable. But if we specifically put thermal cameras to a certain test – is it possible that they successfully work underwater?
Unfortunately, for Thermal Cameras an underwater scenario will not be one of the scenarios, where the performance of this night vision device would be unquestionable. Thermal Cameras will not work successfully underwater, or for some higher generation Thermal Cameras the performance will be greatly hindered and there will be close-to-none useful information or clear image that can come in handy to the user. So to answer our main question, thermal cameras will definitely not work as they are intended to underwater. This is the case, because the water works like a ‘’’blocker’’ for all of the infrared wavelengths and the detecting of emitted heat from certain objects, both factors that are needed for the adequate operation of a Thermal Camera.
It’s crucial to know how a Thermal Camera operates, before you can understand how/why it will/will not perform underwater. Thermal Cameras fully rely on a special lens, that focuses any infrared light emitted by objects in its view. That same focused light is scanned by a phased array of numerous infrared detectors that ‘’catch’’ any infrared wavelengths it detects. Those detectors give the user of the thermal camera a very detailed temperature-based image that is called a thermogram. All of this happens in literally one-thirtieth of a second, from the detection of the emitted light of a certain object to the image that is received by the user.
The main answer to the main question in hand, do thermal cameras work underwater at all, would be that thermal cameras DON’T tend to work well when submerged under a water scenario. But the question doesn’t really end here as there are certain exceptions and points that need further clarification. Keep on reading to find out what the case with the performance of thermal cameras underwater really is.
Thermal Camera Performance Underwater
At first glance, the main thing that hinders the performance of thermal cameras when underwater is that the ‘’thickness’’ of the water blocks out a lot of the infrared wavelengths, that the thermal camera needs for it to adequately perform. You can pretty much look at the water as an ‘’opaque barrier’’ that doesn’t allow for the passing of visible infrared wavelengths.
In a quick simplified comparison – exactly the same way how the human sight cannot see through paint for example, this same way the infrared sensors of the thermal camera cannot ‘’see’’ through a significant depth of water. This is the case because the waves, that the thermal camera can possibly detect, do not pass through water as easy as through the air.
Water can also add an additional harm to the performance of the Thermal cameras – mainly related to the thermal imaging/emitted heat conductivity of the water itself. Water tends to have a much higher heat capacity compared to the air. Comparing the performance of a thermal camera in the two scenarios, water and air – the thermal camera requires 4 times more performance power to successfully detect any minimal emitted heat or infrared wavelength. Practically speaking, this is so because an object in the air will gain/lose its own emitted heat much faster over water, hence it’s much easier to be detected by the thermal camera.
Detecting underwater animals with Thermal Cameras
Seeing through water with a Thermal Night vision camera can be challenging, but is it possible to actually detect underwater animals with Thermal Cameras?
Thermal Cameras can actually help you find and detect fight in the water for example, if the depth is not greater than 10 meters. With Thermal Cameras, while detecting fish , you might also detect different weed lines and kelp paddies in the water at night. Different floating vegetation, which actually attracts offshore fishes, possesses a changing minute-by-minute heat differences that Thermal Cameras can possibly detect.
Thermal Cameras are also sensitive enough to see certain temperature breaks – areas that have the tendency to attract different baitfish and even smaller predators. There has to be one factor present at all times nevertheless – the water temperature to change rapidly within a few meters, so that the Thermal Camera can see and detect those differences, as that is all it relies on.
Thermal Cameras can successfully detect fish underwater and there are even different feedback from Thermal night vision users that successfully go fishing through the night with the help of a Thermal night vision camera. Many angles also gave a feedback that they can often spot schools of smaller bait-fish dimpling underwater and on the surface too, in pitch black darkness. Different schools of fish change the characteristics of the water’s surface, which results in this detection and being ‘’caught’’ by the radars of the Thermal camera.
To this day and based on this information, many anglers use an installed Thermal Imaging Camera for spotting different fish and sea creatures when going out in the night to fish. With FLIR systems for example, the best system setting for this kind of activity would be the Night Running. This setting has an automatic image format set to ‘’ Black Hot ‘’ which mainly detects the heat emitted from living creatures while missing out emitted heat from non-living objects.
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To completely understand the correct answer to the question, do Thermal Cameras work underwater you have to be aware of the water that you are talking about. From wave activity to the depth of the water that you are using your Thermal Camera on really changes the factors and answers the possibility if you are going to be able to use your thermal camera underwater. Shortly, if the water that you are using your thermal imaging camera is muddied and dirtier than normal and has a lot of frequent waves, you will have a much harder time detecting anything compared to a clearer, more calm water condition.