Cooled vs Uncooled Thermal Imagers

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Last updated on May 11, 2021

Thermal imaging is used for a wide variety of tasks and activities. It can be used for military defense purposes, defect detection, assistance purposes, and much more. A thermal camera imager picks up on the heat that objects radiate and displays it so that the object can be seen by the human eye. 

There are two types of thermal imagers, the cooled thermal imager and the uncooled thermal imager. In this article, we’ll discuss both imager types and analyze their applications.

What is a thermal imaging camera?

A thermal imaging camera uses infrared radiation that a body emits to create an image of that particular body. This process is known as thermal imaging, and a thermal imaging sensor utilizes the temperature of a body to create a representation.

This technology was first developed for military use, but thermal imaging systems are now used in a wide variety of industries. The human eye can only see certain parts of the electromagnetic spectrum. It cannot perceive infrared radiation, so a thermal imaging camera helps people see a clear image of an object despite the lack of light.

thermal camera detecting body heat

What is an imager?

An imager, also known as an image sensor or imaging sensor, is something that analyzes and transmits information taken from the radiation of objects to develop an image. An imager picks up thermal radiation, light, or electromagnetic waves and converts them into signals.

Various analog and digital electronic imaging devices use imaging sensors. Camera phones, thermal imaging devices, night vision devices, digital cameras, and radars are just some of the tools that utilize imagers.

What is the difference between cooled and uncooled thermal imaging cameras?

Not all thermal cameras work the same way. More advanced systems have better capabilities, and these are often the same ones that are used to obtain more accurate measurements. This section details the different features of both systems and which one offers a better image quality.

What is a cooled thermal imager?

Cooled thermal imaging cameras have an imaging sensor that is equipped with a cryocooler. A cryocooler is a cooling system that allows for the sensor temperature to dip to cryogenic temperatures. When the sensor temperature is greatly reduced, it also reduces any noise caused by thermal energy by a notch lower than the signal that comes from the objects being imaged.

Cryocoolers are made with parts that work very closely together, and they are also equipped with helium gas that seeps through gas seals. These make cryocoolers break down over time, and they would need to be rebuilt after roughly 13,000 hours of use. Since a cryocooler is a vital part of a cooled thermal camera, this means that a cooled thermal camera would have relatively the same life span.

What is an uncooled thermal imager?

Uncooled thermal imagers are relatively small. These devices do not need to be put into bulky packaging, and they work better for mobile-related applications. Unlike a cooled thermal imaging system, it does not utilize a cryocooler. Because of this, an uncooled thermal imager can be used for more compact devices. Such devices are powered by an uncooled microbolometer, and they are also known as bolometer-based devices.

What is an uncooled microbolometer?

An uncooled microbolometer is a thermal sensor. Complex and expensive cooling methods used to be necessary to operate high-resolution thermal sensors. However, there have been developments over the last few years in infrared imaging using uncooled microbolometers, and they have been widely used in many industries. This is what allows uncooled thermal imagers to operate without the need for cryogenic cooling.

microbolometer

Cooled vs. uncooled thermal imagers

Either type of thermal imaging camera has its own set of advantages. In terms of price, a cooled thermal imager tends to be more expensive because of the necessary hardware. Naturally, an uncooled thermal imaging camera is more budget-friendly. Additionally, an uncooled thermal imager has a more limited range than a cooled thermal imaging system. However, it is still important to determine what the thermal imager will be used for to assess what type is the best to use since they have different capabilities.

R&D applications of cooled thermal imagers vs. uncooled thermal imagers

For R&D purposes, cooled thermal imagers may be more apt. R&D specialists stand to benefit more from cooled thermal imagers than uncooled thermal imagers. Here are some of the features to look out for and how either type of imager compares.

Speed

A cooled thermal imaging camera has an extremely fast camera capture rate. Its camera system allows it to capture even the motion of a rapidly spinning tire. An uncooled thermal imager has a much slower capture rate and does not have such capabilities. This particular feature is important when studying objects that are moving rapidly. Standard IR cameras would show a blur instead of a clear image.

Spatial resolution

Cooled thermal camera systems, as mentioned above, can capture a much greater range than uncooled thermal imaging cameras. A cooled thermal imaging camera has much better magnification capabilities than an uncooled thermal imager. Cooled thermal cameras are excellent for close-up magnification, but they are more apt for ranges over five kilometers, as an uncooled thermal imager would need to be equipped with costly lenses to extend its range.

Sensitivity

Cooled thermal cameras can pick up more minuscule differences in temperature for a longer period than uncooled thermal cameras. This means cooled cameras will provide you with better detail and higher image quality. The enhanced sensitivity of a cooled thermal imager will also allow you to pick up on even the smallest thermal fluctuations, which an uncooled thermal imager cannot do.

Spectral filtering

Spectral filtering is used to remove or zoom into information on an image based on its wavelength. Cooled thermal cameras have spectral filtering capabilities. Through this method, a cooled thermal imager provides deeper detailing and takes measurements of images. For example, if you would want to study coal particle combustion, a cooled thermal imaging camera will allow you to do spectral filtering to image the combustion of coal particles. Uncooled thermal imagers are unable to do this because of their lack of hardware.

Synchronization

A cooled thermal imaging system can be synchronized with other measuring devices. External measuring devices would be able to fit into their mechanism better as uncooled imagers are much more compact.

Why do IR detectors need to be cooled?

IR detectors need to be cooled to showcase better images. As mentioned above, a cooled thermal imager offers more detailed capture results, so users can get the full picture and better image quality. Using a cooled IR detector may show crucial details that an uncooled system would not be able to show.

Randy Angwin

About the author

Randy Angwin is an avid outdoor enthusiast and has been with Smart Scouter since the beginning. He helps create new articles and reviews latest infrared and night vision devices for the site as well as staying on top of the latest trends in the thermal industry. When not working, Randy likes to hunt and spend time with his two German shepherds.

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