Thermal imaging Technology is used in a variety of fields. Advancement in science has helped in the invention of so many thermal imaging devices which is useful in hunting, military, medical, fire fighting, electrical, plumbing, and other sectors.
Using thermal imaging devices, you can improve the visibility even in extremely dark environments by analyzing the infrared radiation emitted by the objects present in the scene.
It is necessary for us to know more about thermal imaging technology since it has applications in a lot of fields including cancer detection. In recent times, thermographic cameras were even used for helicopter rescue buy SWAT team to rescue fisherman caught in the boat.
That’s why we decided to write this mega article which covers the entire thermal imaging Technology and the various thermal imaging cameras, thermal imaging scopes, thermal imaging monoculars, thermal imaging binoculars, thermal imaging goggles and other devices operating using thermal imaging.
What is Thermal Imaging?
Thermal imaging is the night vision technology that helps to see the objects in the dark. Unlike other Night vision devices or NVDs, these thermal imaging devices use heat radiation emitted by objects and convert them into a human-readable format such as thermal image or heat image which contains the complete temperature details of the object.
As every object or life in this world emits heat energy, it can be easily detected by these thermal imaging devices as they need only a small amount of heat to detect and produce the details.
Now, Thermographic inspections become a vital part of many industries.
How Does Thermal Imaging Work?
Visible light or a ‘small part of the electromagnetic spectrum‘ is what helps all the creatures in this world. Similarly, Infrared radiation (IR) is also a part of the electromagnetic spectrum but with ‘more space‘.
Heat can be absorbed, reflected and even transmitted from all the beings. Thermal imaging technology captures this energy and processes it.
The heat radiation emitted by an object is known as its ‘Heat signature‘. The hotter the detected object, the more radiation it will emit.
Thermal imaging devices are also capable of detecting this heat signature and find the minute differences in the heat radiation. And this temperature difference is compiled as a “heat map” that shows different thermal values.
The important component of the thermal imaging device is the ‘heat sensor’ which is connected with the optical lens inside the device.
This optical lens focuses on the heat radiation emitted by the objects.
Another key component of a thermal device is the ‘IR detector‘ to which the focused heat radiation is transmitted.
This IR detector detects the IR energy and collects the temperature details of an object or scene captured.
Thermal or heat sensor inside the thermal device receives this temperature details, process, and send it to the Signal processing unit. Because, the collected details cannot be read or understood by us without processing. So the signal processing unit collects the heat details and converts it into human-readable ‘heat map’ on thermographic display.
This heat map otherwise called the thermal image shows where the heat loss and gain is.
Although still, people prefer black white displays for particular jobs as they reduce the visual errors and provide fine captured details, most of the thermographic displays are in color.
The warmer objects or areas will be in red, orange, and yellow color. Likewise, the cooler parts are usually in purple and blue color in this thermographic display.
As thermal technology processes the IR radiation and not the visible light, they can be used to find the heat emitting objects in any extreme dark environments and hidden places.
Thermal Imaging Devices
Thermal imaging is incorporated in various pro and lifesaving devices. Some of the thermal imaging devices are Thermal imaging camera, Thermal scopes, Thermal goggles, Thermal monoculars, and Thermal binoculars.
Thermal imaging cameras are the handheld devices use thermal imaging technology to view and target the object or area. The special lens inside the camera focuses the emitted IR energy and converts it to the heat zone image with the temperature details. Thermal imaging cameras are used in various real-life applications and services.
Applications of Thermal Cameras
After military thermal cameras are widely used by the Firefighters to see through the smoke or flame to find rescue people and find the hotspot of fire.
Thermal imaging cameras are used by Law enforcement officers for security actions, trap the criminals, investigate crimes and rescue works.
Power line maintenance workers are using this thermal camera to find the overheating joints and prevent the production shutdowns.
Building inspectors are using the thermal camera to ensure the correct thermal insulation in the building, heat or water leaks, to improve the heating or cooling. Thermal imaging cameras are used in Groundwater/Surface-Water Interaction Studies also.
Thermographic cameras can be used to observe physiological activities like a fever in warm-blooded beings.
Homeowners are started using thermal cameras for their regular home inspection or hiring a home inspector for whom this thermal camera is a common tool.
Thermal riflescopes highly used by the hunters to target their prey and make the perfect shot. Thermal scopes are one-eye devices like monoculars that can be mounted on any weapon and rifles. Thermal imaging scopes have the same thermal technology with common scope internal components.
Uses of Thermal Scopes
Thermal scopes are highly used by the hunters to identify the games such as feral hogs, rodents, or coyotes. They allow the users to undetected and see the pray even in any extreme darkness and climatic conditions.
Recent thermal scope models have the sharing options and allowed to upload the videos to the websites including YouTube. The complete hunting and shooting action is recorded in the thermal weapon and shared using mobile apps. Wi-Fi enabled thermal scopes to make this transfer easy. The recorded video clips can be directly stored into the SD card and viewed on computer systems.
Thermal Imaging Goggles
Thermal imaging goggles are head mounting devices mostly used by the hunters and law enforcement officials. If you have to detect or measure the temperature while moving, these thermal imaging goggles can be the best choice as they don’t want you to carry.
Thermal monoculars are almost similar to thermal scopes. But these monoculars are classified as two types.
♦ Handheld monoculars
♦ Head mount monoculars
Handheld monoculars are comparatively lightweight thermal device that you can easily carry around and cost less than another type.
However, these handheld monoculars are not suitable for the longtime hectic operations as you have to hold this throughout.
Head mount monoculars are combinedly used with the headgear so they are entirely mounted on the head. The best thing about this type is that it frees your hands.
The down part of the head mount monoculars is that they are expensive and you have to spend on monocular and headgear.
Thermal binoculars are similar to thermal goggles used by the hunters and travelers. These two-eye handheld devices used to closely see the animals or any objects from long distance.
Bi-ocular vs Binocular
Most of us get confused with Bi-ocular and Binocular while purchasing.
The basic difference between these two is, Thermal binocular has two objective lenses, that collect information from each of them whereas Bi-ocular has only one objective lens, but with an eye-piece arrangement, it allows you to see the generated thermal image with both eyes.
Night Vision Before Thermal Imaging
As we already discussed, thermal imaging is an advanced night vision technology. Before thermal imaging devices, a method called ‘Image Enhancement’ is used to see the objects in the dark.
Image enhancement systems are often called Night Vision Devices (NVDs). This is the night vision technology that most people know about. Night vision devices use the special tube named ‘Image-intensifier tube’ which collect and amplify the visible light.
How Does Image Enhancement Work?
1. The objective lens inside the NVD captures the ambient light and near-infrared light.
2. This captured light is received by the image-intensifier tube. Most of NVDs are powered by the two N-cell or two AA batteries. About 5000 volts output by this tube is transferred to image-tube components.
3. The photons of light energy are converted to electrons using the photocathode which is present inside the image-intensifier tube.
4. When the electrons transmitted using this image-intensifier tube, atoms in the tube release the similar electrons.
Then using the microchannel plate otherwise MCP available inside the tube, the original number of electrons are multiplied by a factor of thousands.
An MCP is a small glass disc which is made of fiber-optic technology and has millions of microchannels (Microscopic holes). This MCP is held in the vacuum and hold metal electrodes on both sides of the disc.
Each and every microchannel is 45 times longer than its width, works as an electron multiplier.
Electrons from the photocathode hit the first electrode of the MCP, and they accelerated into the glass microchannels using the 5000v power transferred between the pair of electrodes.
When the electrons are transferred through the microchannels, there will be a process called ‘cascaded secondary emission’ that is about to happen. This process makes thousands of other electrons to be released in each channel.
The basic reaction is what the original electrons hit the side of the channel by stimulating atoms and making other electrons be released. Then these newly released electrons hit the other atoms and thus create the chain reaction causing thousands of electrons to leave the channel with few entries.
With the small angle of 5-degree to 8-degree bias, the microchannels in the MCP are created. This is to promote the electron collisions and minimize the direct-light feedback and ion of the phosphors at the side of the output.
5. The electrons hit the phosphors coated screen at the end of the image-intensifier tube. The position of these electrons is based on the channel they traveled. The perfect image is produced, because, like the original photons, the electrons also stay in the same alignment. The energy produced by these electrons makes phosphors to reach the excited state and then allows releasing the photons. The typical green image that we aware of is created by these phosphors and displays on the screen which shows the night vision.
6. Using the ocular lens, this green phosphor image is viewed and enables the user to amplify and focus on the image. The user can connect these NVDs to external electronic displays like the monitor to see the image otherwise the user can view it directly via the ocular lens.
NVDs are categorized by generation. Every advanced change in NVD technology builds a new generation.
Generation 0: Unites States Army created the original night-vision systems and used in World War II and Korean War that use active infrared which means an IR illuminator, a projections unit is connected to the NVD. Similar to the normal flashlight beam, this unit projects the near-infrared light beam. This invisible beam is reflected from the objects and captured by the lens of NVD. These NVDs use the anode combined with the cathode to stimulate the electrons.
The first problem of this method is that this stimulation of the electrons changes the images and also reduces tube life.
Second major problem, when used these NVDs in military use, was that it was easy to the enemy countries to duplicate the technology and create their own NVDs to help their soldiers to see the infrared beam projected by the device.
Generation 1: In the next generation of NVDs, the active infrared is replaced with passive infrared. U.S. Army named this NVD as Starlight as they used ambient light from the stars and moon to expand the usual level of reflected infrared in the particular area. So here there is no need for projected infrared light sources. This means these NVDs cannot be used in moonless or cloudy nights. These Generation 1 NVDs also equipped with the same image-intensifier tube with cathode and anode as like Generation 0. The two problems mentioned above are also present here.
Generation 2: With the major changes in the image-intensifier tube, this Generation 2 NVD is established. They are more reliable and provided better resolution and performance compared to Generation 1 NVDs.
The major problem raised in Generation 1 is cleared here, so the Generation 2 NVDs are designed to work at moonless nights and low light conditions also.
To increase the sensitivity to this level, they added the microchannel plate to the image-intensifier tube. In this generation, instead of only accelerating the original electrons, MCP was designed to improve the number of electrons. So the produced image is less distorted and brighter than the previous generation NVDs.
Generation 3: Generation 3 NVDs are currently used by the U.S. military. There are no major changes in the basic technology from Generation 2, but the photocathode used is made with the gallium arsenide as they are more capable of converting photons to electrons. This change made the NVD have increased sensitivity and enhanced resolution. Another notable change we can say is that the ion barrier coating for MCP to increase the life of the tube.
Generation 4: Generation 4 otherwise “filmless and gated” technology is actually a notable improvement of NVDs in both low and high light conditions. In generation 4, the ion barrier coating to the MCP is removed to minimize the background noise which improves the signal to noise ratio. The removal of ion film allows more electrons to enter the magnification stage so the final image will be less distorted and clear. In addition, an automatic gated power supply system is added to a device that enables the voltage of photocathode to turn on and off quickly. With this, the NVD will react to the lighting fluctuation instantly. This is the most helpful feature in NVD systems and so the user can quickly shift from high to low light environments and vice versa without affecting the effects.
Most of the renting night vision scopes available in Generation-0 or Generation-1 technology because Generation 2, Generation 3 and Generation 4 NVDs are most expensive when compared to 0 and 1. But they worth if you care for them properly.
Every single image-intensifier tube undergoes several hard tests to check whether they meet the military requirements. The tubes that are succeeded in the entire tests denoted as MILSPEC and the tubes that failed even in the single test are classified as COMSPEC.
Image Enhancement (NVDs) Equipment
Night vision devices are classified into 3 major categories.
Night Vision Cameras – Night vision cameras can capture the image and connect to the monitor to see or connect to the VCR for recording. These night vision cameras are used in locations where the night vision capability is needed permanently for example on a building. Now most of the new camcorders have built with night vision.
Night Vision Scopes – Scopes are normally mounted on a rifle or weapon and they are like one-eye device such as monocular. Scopes are handheld so they can be used to view the object at the perfect sight and switched to the normal view.
Night Vision Goggles – Though goggles are handheld, mostly worn on the head. They are two-eye devices like binocular so they can have a single lens or stereo lens which is based on the brand. If you want to see the objects while moving then goggles are excellent to have a constant view of dark places.
Night Vision Device Applications
The basic purpose of using the night vision was to trap the enemy at the night. Still, these devices have broadly used by the military for the same purpose added with the targeting, navigation, and security.
Police and security officials use both thermal imaging and image enhancements technology (NVD), especially for surveillance.
Hunters also use NVDs to move at night through the forest areas.
Most of the companies have cameras built with night vision technology to ensure safety and observe the surrounding environment.
Which is Best: Night Vision or Thermal Imaging?
NVDs and thermal imaging devices have created with the purpose of seeing at night or dark. The basic differences between them are the light they used to work and some internal components. In simple words we can say, night vision devices are “passive” which need ambient light to process while the thermal imaging devices are “active” which focus the IR light in that particular area. Let compare them with the basic features and functions of night vision.
Day and Night Use
Both Night Vision and Thermal imaging devices are exclusively used for nighttime applications. But, there may a situation where you have to use the device at day or in bright lighting conditions to get the positive identification of your prey. Most of the night vision devices are designed to work well at dark using the light from the moon and stars and also the internal components of these devices can be damaged if they used in bright light conditions. This is not true in all the case as there are some high tech NV devices have functioned to work at the day time also. However, thermal imaging has won this race with their high compatibility for day and night use as thermal imaging doesn’t rely on light to work.
Night Vision Devices
For The Game
Night Vision Devices won here. Though these devices are work with the ambient light to provide the night vision image, you still receive the detailed image which helps to recognize and identify in the game. Thermal imaging also doing it’s best identifying the game but they lack in providing positive identification like the way NVD do.
Night Vision Devices
Night vision and Thermal imaging are used for security and law purposes so durability should an undoubted feature. Both the devices are durable and reliable in their way of design. Thermal and night vision scopes withstand up to 0.30 calibre recoils.
Night Vision Devices
Night vision devices used for a commercial for decades so they have high longevity. They are available to commoners for a long time. Thermal imaging is used by the military and they become available to the commoners in recent time only. Still, they are expensive products than NVDs.
Night Vision Devices
It is true that both NVD and thermal devices are a luxury and expensive hunting tools. But they are essential gear to have in any type of hunting and tactical situations.
If your needs are serious, then you have to spend dollars on this luxury tool. However, the best choice will surely make the purchase worth.
Let deep into the history of thermal imaging to know where, when and by whom all of these have started.
The History of Infrared Thermography – Evolution of Thermal Imaging
It’s all begun in the year 1800 by Sir William Herschel during his search for new optical material. The original importance of the infrared spectrum or “infrared” how it is called, a form of heat radiation is less possible at that time of discovery than today.
Sir William Herschel (1738-1822)
A Royal Astronomer to King George III, England. He is already popular for his research and discovery of planet Uranus.
1800: Infrared Discovered
Herschel was in the research of finding an optical filter material that could reduce the brightness of Sun image in telescopes while solar observations.
He tried different colored glass samples but they gave the same reduction in the brightness. Later, he was planned to find the samples that can pass very little heat of Sun as the other high sunlight passed samples hurts his eyes.
Herschel was soon decided to do it as a systematic experiment and finding the single material that can provide the required reduction in brightness and maximum reduction in heat. The experiment is taken by repeating Newton’s prism experiment by looking for the heating effect instead of the visual distribution of spectrum intensity.
The bulb in the sensitive mercury-in-glass thermometer is blackened with ink. With this and his radiation detector, he continued the testing of heating effects of different colors of the spectrum which is created on the table top by allowing sunlight via glass prism. Other thermometers worked as controls and placed outside the Sun’s rays.
There is a constant increase in the temperature from violet end to the red end when the blackened thermometer had moved with the spectrum colors. Herschel was not expected this.
A similar experiment in 1777 held by the researcher Landriani, Itlay, had experienced the same effect. Then it was Herschel. He was strong in a point that there must be a point where the heating effect reached its maximum. The measurements limited to vision part of the spectrum and failed to locate this point.
Herschel was sure about the continued heat increase while the thermometer was moving to the dark part ahead of the red end of the spectrum. Finally, when we got the maximum point, he found that it was highly extended behind the red end in what is called as “infrared wavelengths” by us now.
Herschel revealed his discovery by naming this new portion of the electromagnetic spectrum as “thermometrical spectrum“. Sometimes he called the heat radiation “dark heat” or just “invisible rays”.
Now you have to know a fact that it was not Herschel who first used the term “infrared“. In fact, the word is seen in print only after 75 years but still, no one knows who originated it.
Samuel Pierpont Langley (1834 – 1906)
An American astronomer, physicist, inventor of the bolometer and aviation pioneer. He is known for his research and works for Solar physics.
1878: Invention of the Bolometer
Samuel Pierpont Langley has developed the bolometer that can measure the change in resistance of a platinum strip after the electromagnetic radiation exposure.
At the starting of the 20th century, this bolometer technology had tested to detect a cow at 400 meters by measuring its heat. And it was successful.
Kálmán Tihanyi (1897 – 1947)
A Hungarian physicist, electrical engineer, inventor and one of the early pioneers of electronic television.
1929: First IR Electronic Camera Invented
Kálmán Tihany worked on the development of cathode ray tubes and plasma television. He introduced the first infrared-sensitive electronic television camera which could detect enemy aircraft for the British. In 1956 it was officially declared and called Evaporograph.
1945: Near-Infrared Used by WWII Snipers
700 nm to 1 mm, a range of IR wavelengths, though near-infrared, closer to the visible light spectrum, the range goes from 750 to 950 nm. As this night vision method had a range about 100m, Allied and Nazi forces were used this.
1947: First Infrared Line Scanner
Infrared line scanner was first developed by Texas Instruments and the U.S. militarily at the start of the Cold War to use on bombers and cargo planes.
In the late 1950s and 1960s, a single-element detector is developed by Texas Instruments, Hughes Aircraft, and Honeywell. This detector had produced the line images and scanned the scenes. The military has restricted this technology for others as it was expensive and includes delicate military applications. At that time, people don’t know that this detector is going to be the beginning of such great technology ‘thermal imaging’.
In 1966, the First real-time commercial thermal imager had introduced.
In the 1970s, the Pyroelectric Vidicon tube was developed by Philips and EEV. Later it was used as the core of product which was first used by the Royal Navy for shipboard firefighting.
1978: Microbolometer developed
Before the invention of microbolometers, thermal imagers required to get cooled to a subzero temperature to drop the thermal noise emission.
This was completely an expensive and sensitive process.
In the late 70s, Raytheon’s R&D group which became the part of Texas Instruments licensed the ferroelectric infrared detectors.
These detectors used barium strontium titanate (BST) as a coating to the thermal imager’s sensor.
In 1979, Raytheon first revealed the technology to the military.
In the late 1980s, HIDAD contract is awarded to Raytheon and Honeywell by the federal government as a credit to their effort of using thermal imaging technology for military applications. Later Raytheon commercialized BST technology; on the other hand, Honeywell developed vanadium oxide (VOx) microbolometer technology. These both companies received funds from federal programs such as LOCUSP to import the thermal imaging technologies into weapons and equipment system such as rifles and drivers viewers.
1982: Thermography Approved to Detect Breast Cancer
FDA approved to use thermography as a screening process for finding breast cancer. This non-invasive system finds if tumors are mild or deadly. International Academy of Clinical Thermography announced that when compared to regular checkups and mammograms, thermography provides a better detection result (95%) for early-stage cancers.
1987: Thermal Imaging on Movies
Thermal imaging technology is first seen on the mainstream in the movie ‘Predator’. The alien hunter utilized the thermal radiation to hunt his prey. FLIR, a popular thermal device manufacturer now, provided the thermal cameras. In charge of FLIR says they spray down the jungle foliage with cold water before the action, this is to provide more contrast with Arnold Schwarzenegger and other actors.
1990s: Fire Departments Adopt Thermal Cameras
The thermal technology production value got increased and the price decreased after the Gulf War in 1991. Because of that, thermal imaging technology was included in municipal firefighting services. From then on, the manufacturers are concentrated on developing specific safety features in thermal cameras for firefighters.
The introduction of high resolution, uncooled focal plane arrays happened.
In 1994, Honeywell microbolometer was awarded a patent.
2000s: VOx technology
In late 2004, Raytheon sold its Commercial Infrared Division to L-3 Communications.
Lockheed-Martin whose infrared business sold to British Aerospace often called BAE, Boeing and others got a license for VOx technology from Honeywell to develop the infrared detectors for military applications. Nowadays, the thermometers have developed with BST and microbolometer technologies are allowed to non-military applications.
The uses of thermal imaging technology have expanded in various applications from law enforcement, commercial, security, transportation to industrials.
In 1998, first thermal imager from Bullard introduced which were specially designed for firefighting.
In 1992, the standards for teaching thermal imaging courses are developed and approved by The American Society of Non-Destructive Testing. These courses are classified as Level I, II and III.
The early 2000s, the price for infrared cameras continued to decrease and the size of the cameras was getting smaller.
By 2006, infrared cameras with thermal imaging technology were commonly used by the contractors and home inspectors.
2010s: IR-Embedded Testing Equipment
With the deep research and testing into thermal technology, manufacturers like Fluke have added thermal vision to the list of device features. So the 279 FC Thermal Multimeter users had experienced faster troubleshooting and validation, and allowed to send the complete thermal data to the cloud storage.
2014: Launch of the FLIR ONE
The launch of FLIR ONE smartphone attachment allows everyone to experience the infrared spectrum for under $300.
2016: First Thermal Imaging Smartphone
Summer 2016, Caterpillar launched their first Rugged CAT S60 thermal smartphone for $599; it was designed with the FLIR Lepton camera with basic smartphone features. As per a statement by FLIR, very soon thermal cameras will be a default feature present in mobile phones just like the normal cameras.
The high-resolution, uncooled thermal imagers are available at affordable prices.
Cooling Technology of Thermal Imaging
There are two major cooling technologies available for Thermal imaging with which the thermal devices are classified.
» Cooled Thermal Devices
» Uncooled Thermal Devices
The detector used on Cooled imaging technology had cooled to a temperature of nearly 77 degrees Kelvin or -200 degrees Celcius or lower.
The detector used in Uncooled thermal technology had either stabilized to temperatures between -30°C to +30°C or not stabilized at all.
Cooled Vs Uncooled Thermal Imaging
Cooled detector thermal imaging camera has more advantages than uncooled thermal cameras. But they are expensive. The imaging sensor in these modern thermal cameras has integrated with cryocooler to reduce the sensor temperature to the cryogenic temperatures.
This reduction is important because the thermal induce noise should be lower than the signal from the scene which is under detection. Let look into the basic functional difference between the cooled and uncooled thermal imaging.
The IR image shows the difference between the capture rate of the cooled and uncooled system of a rotating tire at 20mph speed. The left image was taken by the cooled thermal camera while the right one was from the uncooled thermal camera.
The left image shows the very fast capture rate of the cooled camera like some may think that the tire is not rotating at all. As you can see the uncooled thermal imager is too slow in capturing the rotating tire.
The below thermal images compare the close-up magnification of cooled and uncooled thermal detectors.
4× close-up lens
13μm pitch cooled camera
Result: 3.5μm spot size
1× close-up lens
25μm pitch uncooled camera
Result: 2.5μm spot size
Cooled cameras sense short infrared wavelengths so they have greater magnification capabilities. As they have excellent sensitivity features, you can use thicker elements without diminishing the signal to noise ratio for better magnification performance.
To check the sensitivity level of the cooled thermal cameras over uncooled thermal cameras, let compare the above images of a man hand on wall.
The above two images captured immediately after the hand was taken from the wall.
This second set images captured after two minutes of hand removal.
Now you can see, the cooled camera thermal image (on left) still shows most of thermal signature of the handprint but the uncooled thermal image (on right) shows only the biased remains of the handprint. The cooled thermal camera clearly detects small difference in temperature and for long duration when compared to uncooled thermal detector.
One commendable advantage of the cooled thermal camera is its ability to perform spectral filtering easily which is not achieved with uncooled thermal imaging cameras.
In the example shown above, a spectral filter is either located in the filter holder back of the lens or into the dewar detector, this is to get the image through the flame. The combustion of coal particles in the flame needs to be measured and characterized. The “see through flame” spectral filter used to filter the cooled thermal detector to spectral waveband. In this waveband, the flame was transmissive and able to capture the combustion coal particles.
The first video image shows only the flame as there is no flame filter.
The second video image clearly shows the combustion of coal particles as there is a flame filter used.
Now you know how and why cooled thermal detectors are best than uncooled thermal detectors.
Infrared Thermometers Vs Thermal Camera
Temperature measurement is the delicate process that can save you from production line shutdowns, manual or natural dangers such as fire, and so much so it is very high investments needed on temperature measuring equipment.
Let discuss the difference between the two major temperature measuring equipment.
Spot IR Thermometer
Spot Infrared thermometers otherwise called IR guns used to measure the infrared radiation emitted in a spot. There are various styles and sizes of IR guns available. Mostly these IR thermometers are used by the electricians, building inspectors, plumbers, HVAC/R techies, manufacturing companies, food processing techies, and homeowners. Few of the usual models used are food grade IR thermometers, gun-style IR thermometers, and visual IR thermometers.
Field of View (FOV):
The FOV is important in any thermometer or camera to provide clear temperature details. The field of view of the device should be filled by the measured target. If the object temperature is different from the background temperature, you will notice the measurement error that is why the distance to spot ratio is essential while choosing the IR thermometer.
The D:S is the ratio of the diameter of the target area and the distance to the target. If the ratio is large then better resolution and small measurable spot size with a given distance. So while choosing the spot IR thermometer check the target distance and pick the model with the right distance to spot ratio.
Thermal imaging cameras have designed with the number of infrared detectors measuring in a pixel array and provide the heat image of the target area or object. The produced image has many values mostly includes the lens, pixel array, and sensitivity.
Benefits of a Thermal Imaging Camera over Spot IR Thermometer
Spot IR thermometers are best for single-spot measurements and they are more affordable in case of temperature measuring applications.
For detecting large areas and at a large distance, thermal cameras are highly recommended. These are best to:
1. Get helpful and clear reports.
2. Rapidly take the measurements.
3. Provide more accurate information.
Thermal Imaging on Phones
Thermal imaging cameras have expanded in their technology and features so the price is also increasing based on that. A typical well-featured thermal camera will cost around $3000 to $5000. This made thermal imaging limited to only affordable people. To solve this issue, thermal device manufacturers decided to ease the thermal imaging and scaling down into the devices like smartphones.
Seek and FLIR like popular thermal camera manufacturers have created thermal imagers which are the add-on device to be mounted on smartphone.
Thermal imagers for smartphones and thermal imaging apps for smartphones, both are doing the same. Thermal imagers can be attached to the phone and they accessed by the corresponding mobile apps. There are specific thermal imagers and apps for both Android and iOS platforms.
Thermal Imaging Apps for Android
There are many Android OS compatible thermal imaging apps are available in the Google play store, below we listed the free top rated android thermal imaging apps.
Thermal Camera Simulated
Thermal Camera Simulated Application provides the real-time thermal effect that simulates the infrared camera. You can see the objects or anything in dark using this app. But the quality of the image is purely based on the mobile camera.
Below is the video of how the Thermal camera insulated app is used to show the thermal vision.
Thermal Camera Fx
Thermal Camera FX allows you to save photos from camera, record videos and apply effects on photos from the gallery.
The effects can be changed while the recording process is going on and thus providing a more active video as output.
VR Thermal and Night Vision Camera Simulated
The VR mode allows the user to see the world as Night vision and Thermal vision.
This app resembles the night and thermal vision using the Image processing directly on device GPU and on each camera frame.
The video clips from the mobile built-in camera are processed by the app in real time with that it generates views similar to thermal and night vision.
Note: These apps only resemble the thermal camera and they won’t detect and provide the accurate temperature details.
Usually, Android phones don’t build in with an infrared sensor so they can’t detect the hot or cold spots.
Thermal Imaging Apps for iOS
Below are some of the popular iOS thermal imaging apps uses.
Night Vision Flashlight
Night Vision Flashlight is one best night vision app for iPhones. Using this, you can change the brightness, colors, and use extra effects easily on a photo. It is a Flashlight Torch. In augmented reality, you can use the Chromatic Filter for thermal vision.
The top right corner button needs to pushed to enable the Thermal Vision Filter to see in the sark. Turn on the Flashlight. Now you can see the place or object at night.
NightVision Light app turns the mobile screen into a red-lit flashlight in your astronomical observation at dark with the full-screen illumination in red color.
The red light illumination can be adjusted to dimmer or brighter by swiping on the screen. The brightness settings are saved for next time use.
Night Vision (Photo & Video)
Night Vision app captures the real night vision photos and videos at the lowest luminosity. This application uses breakthrough technology. It limits the software and hardware abilities of the phone and produces an outstanding effect.
You can change the sensitivity level of the camera while taking photo or recording video to achieve the best result.
These thermal imaging apps help you to experience the night vision and thermal vision effects on your images and videos.
You can use these apps to have fun and prank your friends. However, you can’t detect the heat or water leaks. As these apps use a phone camera, there will be no temperature details available for the scene captured, only the night vision and thermal vision effect is added to the files.
Thermal imagers do thermal imaging on phones in a better way than these apps.
Thermal Imagers for Android
Thermal imagers for Android are directly attached to any Android devices and mobile phones with a camera. They are valuable for home repair, insects control or for natural photography.
Some of the best thermal imagers for Android devices are below.
FLIR ONE Thermal Imager
- Two cameras
- a Lepton thermal module
- a traditional lens
- Allow panoramic shots
- Quick set up and start
- Lightweight and sleek
Seek Thermal Compact
- Detect temperature variation
- Sensor range: -40°F to 626°F
- Clear image from Focus lens
- Sturdy and waterproof case
- Narrow field of view
- Sleek and compact
To know even more and best thermal imagers for Android available in the thermal device industry, check out here.
Thermal Imagers for iOS
The above mentioned Seek and FLIR One thermal imagers are also compatible with iOS devices. The few more iOS thermal imagers are below:
Thermal Imaging Phones
Thermal imaging on phones went to the new height on Feb 2016.
CAT aka Caterpillar, a machinery company announced its official and world’s first Thermal imaging phone with dubbed as CAT S60. This CAT smartphone is part of a collection of Android-based devices.
CAT S60 Thermal Imaging Phone
However, these are not the typical phone for the Android fans instead because they only received the most crucial of firmware updates.
Rather, this is a smartphone for rugged environmental workers and who get benefited from thermal imaging in their day to day works.
If you are the one who needs to be benefited from the thermal vision and not worry about Android updated, this CAT S60 is for you.
- 4.7-inch LCD display
- 1280 x 720 pixels
- Drop-proof to 1.8 meters
- Drop-proof on concrete 6 feet
- MIL-SPEC 810G
- Waterproof to 2 meters(speaker switches open)
- Waterproof down to 5 meters(speaker switches open closed)
- 13MP back camera
- 5MP front camera
- Kevlar weave backside
- Rim around front and back edges
- Several beastly-sized buttons
- Wet-finger compatible Corning Gorilla Glass 4
- USB port
- SOS button connect to a Location Alert app
CAT announced its second version of Thermal imaging phone named S61 exactly after two years from CAT S60 at February 2018.
CAT S61 Thermal Imaging Phone
The Cat S61 is an all in one device that has an integrated thermal imaging camera, laser-assisted distance measuring tool, and an indoor air quality monitor. This Android Thermal imaging smartphone provides a stock experience using the advanced software and security update. Other than the basic hardware improvements, its indoor air quality sensor and laser-assisted distance measurement tool makes it reach most of the thermal users.
- Qualcomm Snapdragon 630 octa-core 2.2 GHz
- 5.2-inch LCD display
- 1920x1080 pixels resolution
- 4GB RAM
- 64GB internal memory
- Front 8 mp camera
- 16 mp back camera
- Drop proof and waterproof up to 3 meters
- 4500 mAh battery
- Matte aluminum frame
- Black plastic edges
- 3 physical buttons at the display
- Polycarbonate lip
- USB-C charging port
- Standard 3.5mm audio jack
Applications of Thermal Imaging
Initially, thermal imaging devices are only available to the military. Later they became commercialized and civilians got the permission to use the devices for home and professionals jobs. Now, thermal imaging for building diagnostics become routine for construction inspectors.
Below you can learn about some of the interesting and conventional applications of thermal cameras in today’s world.
For Non-Destructive Material Testing Industry
Active thermography is used for non-destructive material testing. Mostly Active-thermography is known as the heat flow induction by powerfully intuiting a test object. High precision IR cameras have the ability to capture the heat flow which is influenced by interior material layers and defects. This leads to the various algorithm estimation and enhances the signal-to-noise-ratio which can observe even the small defect. The uses of thermography in this field include:
» In recognizing the deficiencies in the deeper materials.
» In detecting layer structure and insert, and delamination in plastics.
» In detecting CFRPs of the aerospace and automotive industries.
» For interiors structures or honeycomb construction inspections.
» For Automated in-line and off-line solutions, active thermography is used in non-destructive and contact-free material testing.
Aerial Thermography has been used since Korean War to detect the opposite forces and enemy resources.
The infrared camera has the high geometrical resolution and able to detect even small object from the great height. So these cameras have used in monitoring and observing the enemy nation resources on the ground.
Some of its uses on other fields than military are below.
» Estimate the level of environmental damages without involving humans.
» Low smearing is possible by fast IR cameras.
» In integrating visual pictures and GPS data.
» Monitor large geologic properties for changes.
» In checking the thermal storage abilities of biotopes on industrial complexes.
Thermal cameras are highly demanded by the Aerospace industry as these devices are extremely safe and they need highly efficient materials.
Usually, the high frame rate of 100 Hz or the thermal resolution of 20 mK and more are needed.
Thermography in Aerospace is used to detect the active heat flows on newly tried composite materials to make sure the following generation of lighter, efficient, and safe aircraft like today’s models.
It is really a hectic task to deconstruct the car parts but thermal devices provide the non-invasive method of testing that can save total effort and time.
The high competitive and running towards better performance, fuel saving, and lightweight machines encourage thermal devices to offer great detection on electrical systems, machine assemblies, and heating parts.
Only by detecting the temperature changes, thermography shows the defects in products of the automotive industry.
High-Speed Image Capturing Industry
Thermal imaging is incorporated in the field of the testing high-speed image capturing to detect high-speed thermal activities.
Thermography in this field assists to understand the rapid chemical process and provide the information by observing parts and systems.
Thermal cameras used in this field have snapshot detectors which are the new acquisition units and they have the ability to provide the thermographic measurements in the millisecond range.
Chemical industries are getting benefited from thermal imaging cameras in detecting the heat flow from chemical processes.
Thermal imaging technology easily captures the heat flow and provides accurate temperature details, and also analyzes the chemical reactions throughout the chain process.
The contact-less and non-invasive characteristics of thermal imaging keep the people safe away and do all the legwork.
Electronics and Electrical Industry
Thermography benefits electrical systems and equipment.
It prevents humans from having direct contact with electrical circuits, and also the detection and observation can be performed without disturbing the power flow.
Some of the issues detected in the electrical field using thermal imaging are below.
» Loose connections
» Overheating components
» Poor contacts
» Prevented cool passages
Thermal imaging cameras can inspect any mechanical system safely and detect the issues before it causes major problems. The huge machinery that is a hassle to humans can be checked by these thermal cameras for any heat issues. The various thermal imaging applications on this field include:
» In refrigeration systems, air leaks and clogged condenser tubes are found.
» In internal combustion engines, radiator tubes and blocked air coolers can be detected.
» In compressors, fans, pumps, and blowers, unnecessary oil temperatures, increased temperature discharge, and overheating bearings are located and identified.
Material Testing Industry
Infrared thermal cameras provide better performance in testing materials in a non-destructive way.
Everything in this world emits IR energy of temperature range above absolute zero.
So the non-destructive testing can be handled using infrared as they have designed to measure temperature from any surface whether heating or cooling.
Thermal imaging has overflowed in the medical field of both humans and animals.
Thermal imaging is used in the medical industry for more than 50 years.
Earlier, thermography is used to detect breast cancer. Infrared thermal imaging used in connective tissue diseases and to found muscular and skeletal problems.
One example of thermal imaging in this field is the use of ‘Equine thermal imaging‘ to treat horses. Equine thermal imaging helps to identify the disease or inabilities in the horses.
The field of metallurgy ensuring the right materials heated to the right temperature so that it produces the expected result.
Thermal imaging and infrared cameras assist the best in this field. Thermography in this field is used to reduce the consumption of energy by detecting deficiencies in the heating chambers, cracks, or other issues related to insulation.
The speedy process and accuracy of thermal imaging make it beneficial to the metallurgy industry.
The high-quality monitoring is required in plant inspections to avoid the accidents and to make the working area safe to the employees.
Electronics and manufacturing companies are using thermography for predictive maintenance to find the issues.
Infrared systems provide a reliable inspection without risking anyone live.
After thermal camera had been used on the battlefield, they have been serving their best in the field of security.
There are commercial and professional thermal security cameras have used in home security and companies.
Other than these professional and field-based applications, thermal imaging devices are used by hunters, wildlife researchers, survivors, and campers.
Popular Thermal Imaging Manufacturers
As the value for thermal imaging technology grows, many of machinery manufacturers step front to produce the thermal imaging devices like cameras and scopes. Let see some of the popular and promising manufacturers of thermal imaging technology.
FLIR – Best Thermal Imaging Camera
FLIR, also known as ‘Forward Looking Infrared’, was established in the year 1978 to explore the high-performance, affordable thermal imaging systems development for airborne applications.
At the end of the 1980s, FLIR started extending its development in thermal imaging technology, created the hand-held and laboratory systems for the various commercial fields which need the ability to detect and inspect the temperature changes more than only requiring high image quality.
At present, FLIR works in many locations around the world and has a total of over 3,000 employees and FLIR thermal cameras are widely used in various fields.
FLIR TG165 is the editor’s choice for Best thermal imaging camera.
ATN – Best Thermal Scope
ATN (American Technologies Network) was founded in 1995, in today’s market they are one of the leading Tech Optics manufacturers. ATN is the leading developer of 4K Resolution Digital Smart Optics that can be operated in both Day and Night operations, and Thermal imaging devices for great night vision actions.
ATN optics are perfect for military, hunters, outdoor fanatics, and law enforcement.
In 2018, ATN introduced its 4th Generation line of gears in both Day and Night systems added with New Thermal product line. These new lines hold the improved image processing abilities, new Obsidian 4 core with Dual Processor, and fast performance.
ATN Thor HD 384 Smart Thermal Riflescope is the editor’s choice of Best thermal scope.
ATN is also listed as the top-rated brand to produce the best thermal imaging binoculars.
ATN Binox-THD is our editor’s choice for Best thermal binocular.
Yukon aka Pulsar – Best Thermal Monocular
Yukon Advanced Optics Worldwide is a Lithuanian company that created and developed outdoor gears like binoculars, scopes, rangefinders and some night vision systems, was founded in 1998 by a group of friends who tried to expand the human abilities.
In 1999, they released their first night vision device that was Generation 1 monocular.
In 2008, The Company had decided to broaden its range of night vision optics, this leads the company to create a new brand that can be used in law enforcement companies and professionals. This strategy explores the new trademark called Pulsar which used the Pulsar Quantum, a British made thermal imager.
From then, Pulsar has been producing the high-quality night vision devices like thermal scopes and monoculars.
Pulsar Helion XP is our editor’s choice for Best thermal monocular.
SEEK – Best Thermal Imager for Smartphones
In 2014, Seek Thermal entered the thermal imaging field by launching their first smartphone add-on thermal imager for just $199.
In 2015, in additions to its smartphone thermal imagers, it has effectively followed OEMs to add its 206 x 156/12 VOx microbolometer cores in their thermal cameras for real-time applications such as building inspection, security, surveillance for drones, automotive night vision, security cameras, etc.
In 2016, Seek Thermal launched its 320 x 240 Smartphone Thermal Imager. After a few months, they had introduced the RevealPRO Camera/Flashlight.
In 2018, Seek Thermal introduced its two new palm-sized thermal imagers using the company’s 12 micron VOx microbolometers such as Seek Shot (206 x 156) and Seek ShotPro (320 x 240) for Building and Electrical Inspection.
Seek Thermal XR is the editor’s choice for Best thermal imager for smartphones.
BLACK + DECKER – Best Budget Thermal Camera
BLACK + DECKER is a well-known manufacturer for industrial and household power tools.
In 1910, two young entrepreneurs—S. Duncan Black and Alonzo G. Decker launched a machine shop with just $1200.
In 1916, BLACK+DECKER patented for its ½-inch portable electric drill.
In 1917, the first large-scale manufacturing plant opened in Towson, Maryland, Baltimore.
In 1946, the world’s first portable electric drill for consumers is released by BLACK + DECKER.
This is how their power tools machinery development started and it is still going on.
Fluke – Best Mid-range Thermal Camera
Fluke Corporation is manufacturing industrial test, measurement, and diagnostic equipment. It is a subsidiary of Fortive, started in 1948 by John Fluke.
On October 7, 1953, by John Fluke, Fluke Corporation was launched as the John Fluke Manufacturing Company, Inc producing electrical metering devices.
Fluke Corporation is a global corporation that creates, develops, designs and sells the electronic test instruments for educational, industrial, service, scientific, and government applications. Fluke Biomedical and Fluke Networks are sister organizations.
In 1998, Fluke was sold to Danaher Corporation.
The contributions of Fluke Corporation in test and measurement technology in the past 10 years include thermal imaging and wireless remote displays.
Fluke TIS20 is the editor’s choice for Best Mid-range thermal camera.
Armasight Inc. was founded in 2011.
Now they have joined with FLIR and producing thermal devices with FLIR’s thermal imaging technology.
Armasight by FLIR Zeus 336 is the editor’s choice for Best Mid-range thermal scope.
Questions About Thermal Imaging
1. What material blocks thermal imaging?
Any warm-blooded body whether it is animal or human can be detected by thermal imaging devices from their infrared radiation.
One of the most effective materials that block thermal imaging is Glass. Yes, you cannot see through glass using thermal imaging because glass is a reflective material so here thermal imaging camera detects reflected temperature coming off objects.
2. Can thermal imaging be used during the day?
Unlike regular digital cameras sensors that detect visible light, thermal imaging camera sensors detect the heat signature emitted. With the special optical lens, thermal cameras focus the infrared energy and sensor detects it. By knowing this, thermal cameras don’t worry about the light so they will work as best as they do in darkness.
3. Can thermal imaging see-through plastic?
The window can allow the light to pass through but not the infrared. Meanwhile, thick plastic bags which has a high amount of Silicone does not allow light to travel.
A human eye will see what is behind the window, but it can’t see what is behind the plastic bag instead the person will see only the color of the bag.
Silicone is transparent to infrared, so thermal imagers will detect the temperature behind the plastic bags.
4. What is the difference between Thermal imaging and Mammography?
Mammography in the medical field produced the images called Mammograms which are captured with X-ray technology to check for abnormalities in the breasts like a tumor.
When doing a mammogram, the breast is compressed between an X-ray that is transmitted through the breast tissue and two plates.
Thermography also used to test breast cancer as it detects and records the temperature changes in the skin.
A type of thermography called DITI (Digital infrared thermal imaging) used in the testing of breast cancer that uses an infrared thermal camera to capture the pictures of the different temperature areas in the breasts. Then these details are shown as a heat map in the camera display.
5. What is the use of thermal imaging in satellites?
Based on the type of Satellites, the use of thermal imaging varies. Thermal imaging in weather satellite helps to find the hot and cold areas of Earth which will help to identify the geothermal exercises. The heat images from the satellite can be used for rain pattern, weather forecast, cyclone intensity. Taking Earth’s temperature using thermal satellites can provide valuable data about global warming and water need for the growing population.
6. What is Equine Thermography?
Equine Thermography is a type of thermography for horses. Equine Thermography for horses can detect and show the injury areas and how depth it is up to three weeks before your horse displays any symptoms.
Equine thermal imaging is precise in identifying lesions in ligaments and tendons, as a predictive measure to rapid recovery time, and letting your horse back to normal as soon as possible.
7. How thermal imaging used in Agriculture?
Thermal values of plant leaves are affected by the complex heterogeneous structure. For this, it is useful to research in every plant with thermal sensors as they can provide accurate and high-resolution thermography.
The thermal values of crops may be influenced by environmental depended thermal measures. So we need a valuable crop image based weather conditions to compare it with other images from different growth periods. Thermography can be used in all agricultural processes where there is heat loss or gain.
Some of the potential uses of thermal imaging in agriculture are nursery monitoring, irrigation planning, soil salinity test, yield calculation, maturity test, etc.
8. Is thermal imaging camera on Drone beneficial?
A thermal imaging drone camera is a powerful aerial tool. It can be widely used in various conventional applications such as construction, mining, electrical, firefighting, hunting, search, etc.
Thermal drones help to find the heat spots from the aerial view at any great distance. Thermal imaging camera on drones has highly beneficial in Photovoltaic power plants. This will avoid risking human life on dangerous plant checking and analysis.
9. Is thermal imaging can be used for fishing?
The underwater fishing camera can be used on any boat to find anything under the water surface, but it is also important to know what is there when you boating in the dark. A thermal imaging or infrared camera can be used to find any hidden hazards or danger under the water surface even in the complete darkness. But thermal cameras are not recommended for finding the fish as the devices only detect the warmest beings.
10. Is thermal imaging used in lie detection?
Yes, the thermal imaging camera has been tested in finding the liars. The University of Bradford in the north of England have created the lie detector using the thermal imaging technology and they have tested the device in an interview.
Hassan Ugail, director of the Center for Visual Computing at the university once said when someone is doing anything abnormal or unusual, the usual brain activity will change and thermal cameras can be used to detect this difference.
The ‘Future’ of Thermal Imaging
Clearly, thermal imaging cameras create a revolution in security and surveillance departments.
The researchers and developers are expecting that thermal technology will continue its updates especially in the part of improved detector performance and minimized noise equivalent temperature difference and the components.
We can expect to have large arrays (640×480, 1024×1024) and lightweight cameras that use less power.
The future cameras are integrating infrared, visual and blended images. Cameras that are allowing live infrared images to be overlaid directly onto the visual camera pictures.
Cameras with wireless network communication and connectivity. The devices will have the ability to store and transfer the thermal images, sound, and details to the PCs in the field directly.