Thermal scopes work by using a microbolometer sensor to detect infrared radiation (heat) emitted by objects, then converting these signals into a visible image displayed on screen. The process involves four key components: a germanium lens that captures infrared energy, a sensor array that measures temperature differences, a processor that converts data to pixels, and an OLED display that renders the thermal image in color.
Initially developed for the exclusive use of the military, thermal imaging allows hunters to hunt in low-light situations, sporting the same vision as nocturnal wildlife.
It's exciting to watch hunters track their prey, or law enforcement spot intruders in pitch black darkness, but what is thermal vision and how do thermal scopes work? This blog investigates thermal technology and how heat sensing scopes work, shedding light on their many uses beyond hunting and warfare.
What is Thermal Imaging?
Thermal imaging is a technology that detects heat emitted by objects and converts it into a visible image. Instead of relying on light, it visualizes temperature differences, so objects become visible even in complete darkness.
To understand how a thermal imaging scope works, it's necessary to first understand thermal imaging itself.
All objects, animate and inanimate, emit heat in the form of electromagnetic radiation, also known as thermal radiation. The source of the heat is the constant vibration and movement of the atoms and molecules that make up the fabric of all physical matter – internally, everything is in constant motion, even if we are unaware of it and can't detect it visually.
In practical terms, thermal imaging works by detecting the heat that results from these minuscule movements and turning it into an image that can be seen in darkness or poor visibility.
Objects stop emitting heat at extremely low temperatures. At absolute zero, which is the lowest possible temperature, -273.15°C (-459.67°F), object stop emitting traceable heat.
How Thermal Scopes Work
Thermal scopes work by capturing infrared heat through a specialized lens, measuring temperature differences with a sensor, processing that data electronically, and displaying it as a visible image. Each component contribute to turning invisible heat into a visible image.
There are four key components to how thermal scopes function:
1. The Thermal Scope Lens
While standard glass lenses in cameras or rifle scopes detect visible light, thermal scope lenses detect heat in the form of infrared radiation. To do this, thermal scope lenses are made from special materials, usually germanium, which is transparent to infrared waves, allowing them to pass through.
These special materials necessitate specialized protective coatings, which contributes to the cost of these lenses.
A thermal lens performs three functions:
- It collects heat energy emitted by the objects it is focused on and directs it toward the sensor.
- It focuses the infrared energy onto the microbolometer sensor array, sending accurate temperature data to each sensor element.
- The focal length of a lens determines how the infrared radiation from the object in the environment is focused onto the thermal sensor. More advanced thermal scopes feature variable magnification systems that surpass traditional fixed magnification designs, allowing you to zoom in and out of your field of view.
2. Microbolometer Sensor Array
Microbolometer sensor arrays consist of thousands of tiny heat-sensitive elements arranged in a grid. Each element represents a single "pixel" that reacts to and measures incoming heat.
Each element absorbs the energy directed to it, which leads to temperature changes, altering its electrical resistance. The microbolometer measures these heat differences created by different wavelengths and sends the information to the processor.
3. Processor
The processor receives the resistance-change data and converts it electronically into image data by assigning a pixel to each signal it receives. Thermal image processing leverages several enhancement stages, such as non-uniformity correction (NUC), contrast enhancement, and calibration algorithms, plus noise reduction.
The sensor and processor work together to produce the image, which is then sent to the display.
4. Display
The image data received from the processor appears on the display in a range of colors according to the intensity of the infrared emission – different intensities are represented by different colors. Most thermal scopes use OLED (Organic Light-Emitting Diode) screens to ensure high-brightness displays with exceptional contrast ratios, and a range of color palette options to differentiate between warmer objects typically shown in reds and yellows and cooler object displayed in blues or greens..
Thermal Vs Night Vision –Are They the Same?
Thermal imaging and night vision are fundamentally different: thermal imaging detects infrared heat, and night vision detects and amplifies ambient light to make objects and scenes more visible in low-light conditions.
With thermal vision technology there is nowhere to hide – the slightest heat signals from creatures, human and non-human, or objects can be detected by thermal optic devices, negating any obscurity presented by fog, smoke, rain, and even total darkness.
Night vision enhances existing light, such as moonlight, starlight, or distant streetlights to produce an image that's easier to see in low-light conditions. There must be a source of light, however small, for night vision devices to work. Thermal imaging, on the other hand, requires heat, not light to produce images.
Key Areas of Application
Thermal imaging is used across a wide range of industries to improve visibility in challenging conditions. The ability of thermal imaging to function without light makes it valuable for security, outdoor use, emergency response, and wildlife management, among other uses.
1. Hunting
Within the outdoor shooting and hunting community, thermal imaging is popular for its ability to make visible the invisible. Thermal imaging helps hunters find game in all weather conditions, in dense vegetation, and at any time of day or night.
Crucially, this technology can identify aspects like age and sex accurately, preventing pregnant or young animals from being killed.
2. Species and Pest Control
As a wildlife management practice, thermal imaging assists with species control and pest control. It helps to identify species such as wild boar, deer, foxes, and predators like coyotes whose numbers have become too large.
In agricultural settings, thermal imaging allows farmers to conduct their control activities at night without disruption to daytime agricultural activities. Thermal imaging technology also greatly enables locating wounded game, outperforming traditional tracking methods in challenging light conditions.
3. Surveillance
Security has become a necessary priority for homeowners, businesses, and local governments. Thermal imaging offers distinct advantages for security by detecting heat signals in total darkness and across large areas. Thermal technology allows thermal cameras to monitor a perimeter, detect intruders, and enhance crowd safety in conditions that may render traditional security cameras ineffectual.
4. Search and Rescue Operations
The advent of thermal vision has considerably improved search and rescue operations. Search and rescue teams can leverage the unique ability of thermal imaging devices to locate heat signals from injured or trapped individuals in the aftermath of events such as earthquakes, fires, or industrial accidents.
5. Law Enforcement and Safety
Thermal technology is also widely used in law enforcement. Thermal scopes enable officers to detect and track criminal suspects in all conditions, helping to apprehend suspects, prevent crime, and improve operational safety.
A heat-sensing scope can also detect heat signatures left at a scene, assisting law enforcement with tracking down suspects and recovering and preserving evidence.
Cost Implications of Thermal Scopes
Thermal scopes cost considerably more than traditional optics due to the advanced technologies and specialized components required to make them.
Key factors behind the price include:
- Specialized sensor technology involving a microbolometer sensor array that requires precision manufacturing and quality materials.
- Expensive infrared lens materials, such as germanium that allow infrared radiation to pass through the lens.
- Powerful on-board processing and high-quality displays are required to process data and produce high-quality images – all of which are costly.
- Tough materials and rugged design are necessary to enable thermal scopes to perform optimally in harsh conditions, extreme temperatures, humidity, and recoil, which adds to the cost.
Evaluating When a Thermal Scope Is Worth Using
For hunter, a thermal scope is most effective when visibility is limited, such as at night, in dense vegetation, or in poor weather. Its value depends on the environment, target species, and the time of day..
It's not every serious hunter that needs a thermal scope. The time of day, weather conditions, and the hunting environment will determine whether infrared imaging offers a meaningful advantage.
If you mostly hunt during the daytime and in open savannah with clear visibility, traditional optics or night-vision equipment will provide all the vision you need at a more affordable price.
On the other hand, if you are after nocturnal species like wild boar or need to hunt down coyotes, hogs, raccoons, or jackals, a thermal optic scope fixed to your rifle will make your task much easier. The ability of thermal scopes to reveal heat signatures in low light, complete darkness, or dense cover makes them particularly useful in these conditions.
For hunters wanting a tactical advantage and hunting hours that stretch through the day and night, thermal scopes offer advantages that conventional optics cannot equal.
FAQs
1. Is thermal imaging better than night vision for night hunting?
Yes, since thermal imaging detects heat, animals can be spotted and tracked in total darkness, pouring rain, fog, and, dense forests.
2. What is thermal imaging and what is it used for in hunting?
Because thermal scopes capture heat rather than light, they can detect animals hidden by
dense foliage and poor light conditions like fog, extending the hunting hours and increasing potential hunting success.
3. Is an infrared scope legal for hunting?
Yes, thermal scopes are legal for hunting in many places, but not everywhere and not for all purposes. Different countries and local authorities have different regulations. In some places, they are legal for pest control but not for shooting game. Always check with local authorities about restrictions.
4. At what distance can a thermal scope detect an animal?
Top-quality scopes can detect heat signatures beyond 2,000 meters. With entry-level scopes the distance is 500-800 meters. Accurate identification is only possible at 400 - 800 meters.
5. Can thermal scopes be used by divers?
No. Most thermal scopes are water-resistant, but they can't be used in water because water absorbs infrared radiation, which is what thermal scopes are meant to detect.
Conclusion
By sensing infrared heat, thermal scopes enable hunters, law enforcement, and outdoor enthusiasts to see what would otherwise be invisible to the naked eye.
Infrared sensing has become integral to safety, security, diagnostics, and automation across industries, commerce, and defense. While thermal scopes are mostly used in defense, law enforcement, and wildlife monitoring, they are also increasingly used by hunters seeking improved visibility in challenging environments.
For firearm and outdoor shooting enthusiasts, it's crucial to know what thermal vision is and how a thermal imaging scope works. Choosing the right thermal scope, or heat-sensing device depends on the intended application, whether for hunting, professional use, or personal safety. For more guidance on thermal imaging devices, contact our expert support team.
