What is IR Thermal Infrared Imaging Cameras Imaging & White Paper Applications for Security & Surveillance MWIR Cooled Thermal VS LWIR Uncooled

 By Infiniti Electro Optics

Thermal cameras, unlike traditional visible cameras, use heat rather than light to see an object, giving them a huge advantage over other imaging technologies. Using minute differences in infrared (IR) radiation they produce a high-contrast thermal image in complete darkness. It is unaffected by bright light and has the ability to see through obstructions such as smoke, dust, and light fog. This makes thermal ideal for a number of applications including but not limited to surveillance & security search and rescue, fire, marine and land navigation, machine vision, and wide area situational assessment 24/7 day or night.

See it all 24/7 Day Night                            

Everything above absolute zero (-273°C) emits thermal IR radiation. Thermal cameras convert this into a digital image that can be displayed, distributed and recorded. Humans, animals, and vehicles are very hot in contrast to a background making them easily detectable by a thermal imaging camera, even at distances up to 50km using Infiniti Viper HD MWIR cooled MWIR thermal with 1400mm GE lens. This technology gives you state-of-the-art protection that can be used in the most demanding applications where the limitations of traditional visible day night IP/CCTV camera technologies just cannot compare in terms of detection and night vision distance even in complete darkness.

See Through Fog/Haze & smoke    IR Infrared radiation (Heat) passes through smoke, dust, modest foliage, and light fog with ease, making a person clearly visible even in the worst lighting conditions. Thermal energy is passive and, unlike other technologies, does not artificially increase light or require illumination for clean crisp images both day and night for detection of intruders at extreme ranges, Infiniti's HD Cooled thermal cameras let you see further than any other night

vision technology with up to 55km of vehicle detection and 40km human detection based on DRI johnson criteria. 

Reliable Robust Imaging for long range target detection

There are also certain situations where thermal imaging can be better than regular CCTV/IP CCD/CMOS cameras even during the day. Standard cameras can be rendered useless by direct or reflected sunlight, and they rely on the contrast in order to identify an intruder. In areas where contrast is poor, visible cameras can be rendered useless. Since humans always give off much more thermal energy than their environment they are easily picked up by video analysis software or human viewers. Trespassers hiding in shadows or bushes are easily spotted, providing maximum protection of your assets

Passive Stealth Imaging

Thermal imaging is a passive technology meaning that, unlike other active night vision technologies, thermal does not artificially increase light or require any illumination or light source it uses heat which is emitted by all objects above absolute zero. This is extremely important as standard Active IR (NIR 750nm to 840nm) illumination emits a faint red glow which can allow intruders to find possible blind spots in your surveillance system. There are many applications that require stealth, such as SWAT teams, investigation units, counter surveillance and military personnel who require their presence to be undetected in order to achieve their objective. Thermal is the best technology for these applications as it is a completely passive technology allowing you to conduct covert reconnaissance day or night.

Types of Thermal Infrared Cameras Cooled MWIR & uncooled LWIR 

Cooled InSb & MCT MWIR Medium Wave Infrared Thermal Imagers

 Cooled thermal imaging cameras are traditionally made out of Indium Antimonide (InSb) but recently Mercury Cadmium Telluride (MCT) detectors are available as well. InSb and MCT are very similar; both require an integrated cryocooler, hence the name cooled camera, and come in 640x480~ HD resolution. . Since thermal cameras work by using heat waves cooling the core exponentially increases the sensitivity increasing both range and performance.

Cooled Thermal Cameras use Cryocoolers

Since the cooler has to constantly keep the core well below freezing the cryogenic cooler is continuously running and requires replacement every 8,000~10,000 hours on InSb detectors and 15,000~20,000 hours of operation on MCT detectors (Not the rated distance are often half the actual performance in hot climates) . MCT cores are more expensive but since they require less cooling they have a longer lifetime and lower cost of ownership over InSb giving them a higher ROI. Cooled thermal infrared cameras are extremely sensitive to minute temperature differences allowing even a fraction of a degree temperature difference between a target and the background clearly visible. Cooled cameras work on mid-wave infrared or MWIR and typically use wavelengths of 3-5μm (3,000nm–5,000nm).

The combination of a cooled image core and the ability to work on the MWIR spectrum results in ultra-long range detection capabilities up to 55 km|35 miles, even if there is only a few degrees temperature variance between the target and the background. While cooled cameras are a significant investment. and are considerably more expensive than uncooled, and require regular maintenance their superior range and performance allows them to replace up to 8 uncooled cameras making them a viable and cost effective solution for applications such as homeland security and coastal surveillance.

Uncooled Thermal Infrared LWIR Long Wave Infrared (VOX) 

Uncooled thermal cameras are infrared cameras that do not require cryogenic cooling. A common detector design is based on the microbolometer, a tiny Vanadium Oxide (VOx) resistor with a large temperature coefficient on a silicon element with large surface area, low heat capacity, and good thermal isolation. Changes in scene temperature cause changes in the bolometer temperature which are converted to electrical signals and processed into an image. Uncooled sensors are designed to work in the Long-Wave Infrared (LWIR) band from 7 to 14 microns (7,000nm–14,000nm) in wavelength where terrestrial temperature targets emit most of their infrared energy. Infinit Optics Uncooled infrared cameras provide up to 20km of detection and have no maintenance costs or ITAR/ import restrictions in most regions making them much more common than their cooled counterparts and are no longer just availible to Military and defense applications.

Germanium Thermal Infrared Lens & Optics                           Since thermal infrared cameras use heat (3μm–14μm spectrum) they do not use standard glass optics. Instead, they use a rare earth metal called Germanium (Ge). Just as a standard glass lens focus light and determines the view of visible/CCTV/IP CMOS or CCD camera GE focuses thermal engery (heat) to a thermal infrared sensor. Principles and terminology such as F-stop, & Focal length apply to both thermal and visible len's difference is one is light and other is heat. Germanium, because it is a rare earth metal, is much more expensive than optical glass making Ge lenses much more expensive than their visible camera counterparts. Due to their higher cost, thermal cameras tend to have a much smaller lens, and uncooled cameras usually have a fixed lens that does not exceed 100mm.

The Importance of F stop for Thermal Imaging

While Germanium is the best material for thermal lenses thermal energy is not is not as efficient at delivering heat to a thermal sensor as optical Glass is at delivering light to a visible CCD/VMOS sensor. This means the larger the lens the more heat loss that takes place resulting in lower performance and range. This is why Ge lenses are often smaller and continuous zoom lenses offer less performance than fixed lenses especially at focal lengths greater than 150mm. This is not to say that thermal zoom lenses do not have merit as they allow you to gradually zoom throughout the whole focal length while staying in focus. However, this advantage comes at a cost of range and performance. White paper on F stop and aperture 

Infiniti Electro Optics Low F stop precision GE optics

 Our engineers have combated this problem by building and collaborating with leading optic suppliers to offer continuous zoom lens's that have large focal lengths but are also bigger while which allows them to gather more heat and thus have a lower f-stop resulting not only in continuous zoom lenses with longer ranges. This results in not only longer ranges but increased performance. Our uncooled germanium continuous zoom optics boast an industry-leading f1~f1.1 aperture, compared to others that are f1.5~F1,6.

What is the relationship between lens f-number and a camera performance -FLIR Link

 "In general, uncooled thermal imagers require relatively fast optics for best performance. The most common figure of merit used to describe how well a thermal imager performs is known as Noise Equivalent Temperature Difference, or NEdT. The units of NEdT are milli-Kelvins, or mK (thousandths of a degree). The lower the NEdT value of a system, the better the performance. Because the f/number of a lens has an effect on how well the system will perform, and in order to be able to fairly compare the performance between thermal imaging systems, the specification for NEdT is often referred, or normalized, to f/1.0.

A simple formula can be used to calculate how the NEdT of a thermal imager will be affected by changing the f/number. The formula involves 3 variables: 1) the f/number of the optic being used on the camera; 2) the NEdT that is typical of the camera with that optic; and 3) the f/number to which the camera performance is to be normalized (usually f/1.0). By assigning a value of X to variable 1, and Y to the NEdT value of the camera using optic X, then the normalized value (to f/1.0) can be calculated as: (1.0÷X)2 x Y. As an example, assume a thermal imager with an NEdT of 87mK using an f/1.6 lens. To normalize its performance to f/1.0, the calculation is: (1.0÷1.6)2 x 0.087; or (0.625)2 x 0.087; or 0.3906 x 0.087; equals 0.03398; which is 34.0mK.

This means that a camera with an f/1.6 optic has about 2.5 times less thermal sensitivity than the same camera with an f/1.0 lens."

This means our F1.0 optics allow 2.5x more thermal energy than a F1.6 lens. Our 180mm zoom lens is F1 to F1.1 and our 270mm is F1.3. When We pair our uncooled VOx core with our precision-engineered germanium lens with a dual-FOV design allowing you to view targets at either 95mm or 275mm. This allows for long-range detection of targets by switching between a 6.5° and 2.3° field of view. This lens also feature auto-focus capabilities, delivering crisp, clear images even when changing in between FOVs, ensuring optimal performance and situational awareness in the wide field of view and crisp details in the narrow field of view allowing for 20km of uncooled non ITAR imaging which is up to 2x our competitors and even exceeds some cooled thermal systems. Infiniti also offer HD cooled thermal camera systems with around 1400mm focal length for 50km of vehicle detection and HD resolution. A thermal camera is not about the specs of the individual components but about the performance of the integrated system there is major difference between a F1.0 100mm lens and the standard F1.6 if though they look the same on a spec sheet the F.10 will have a qualitative difference in clarity and performance achieved. 

If Thermal is so great why use multi-sensors?

Multi-Sensor EO/IR PTZ Camera Systems

Thermal imaging systems boast a variety of advantages, but because they use passive heat radiation they only have the ability to render images in 256 grey scale. Visible cameras operate on the same spectrum as the human eye and reproduce images with up to 16.7 million colours, allowing you to identify a target rather then just detect and classify it. When there is sufficient amounts of light visible cameras often have larger zoom lenses to optically zoom on a target with focal lengths over 5000mm and resolution 12k for video and 40MP for snapshot. In short Thermal is the best imaging technology for long range detection and situational assessment and night vision over 5km however other technologies like SWIR, Visible, NIR, ZLID illumination provide advantages over thermal in terms of zoom range, resolution and ability to provide identification, not just detection. This is why Infiniti Electro optics custom builds PTZ cameras implementing multiple technologies in order to meet the requirements of the customer and application to provide long range complete turnkey solutions for long range Detection, Recognition & Identification on Gyro stabilized military grade PTZ camera systems.

Thermal ratings are misleading:

Detection, Recognition, and Identification (DRI) are terms used to compare the performance of thermal infrared cameras. This paper explains these standards that have been set in place by The Night Vision Thermal Imaging Systems Performance Model, also referred to as the Johnson criteria, the universal standard for measuring thermal cameras.

DRI is a universally accepted set of standards providing a means of measuring the distance whereby a thermal sensor can produce an image of a specific target. This tool was initially developed by the US Army and takes into consideration many different criteria such as noise, array size, optical blur, lens depletion, aperture, atmospheric depletion, detector pitch and much more. It is important to pay attention to the following definitions, as they are not what many people expect when they see these terms.

It’s all in the pixels

As you can see the terms detection, recognition, and identification can be quite misleading, especially to end users who do not have a military or electro-optics background. In addition, the ratings for detection, recognition, and identification are not determined based on perception, but rather are calculated based on their pixel counts. The original 1950s specifications were based on much older monitor technologies. While they have been updated from line pairs to pixels in an effort to modernize the standard, the increasing resolution of thermal sensors has shrunk the perceived size of these images in relation to the overall field of view, which is not measured anywhere in the standard. These changes are important to keep in mind when looking at DRI ratings. For example, our high-res uncooled thermal sensors have a resolution of 640×480, which is over 300,000 pixels. Human “detection” only requires 3.6 of those pixels and “identification” only requires 230 pixels, which is an extraordinarily small portion of the screen that can easily go unnoticed by the human eye. In fact, if this page were the size of your video feed, the area required for a human detection rating would be equivalent to the size of this rectangle: Even when magnified, the amount of detail visible at the detection, recognition and identification distances is not as high as one might expect, as seen in the chart below. Industry Standard DRI Requirements

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