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What Is a Thermal Scope & What Do They Look Like?

L.p. Brezny | Updated February 25, 2024 | Why You Should Trust Us | How We Earn Money
cover photo of what is a thermal scope showing an IR image of a hand, article title, and logo

You’ve probably just heard about these ‘thermal scopes’ and want to know what they do exactly. How’s it different from other scopes?

And that’s fair because more and more people are talking about it these days, and no way are you going another minute not knowing what this novel and, apparently, handy tool can do.

Well, first of all, it’s not new but it’s certainly very useful.

We’ll get right into what a thermal scope is and how it works, all the different styles you can find, and the many industries you’ll find it in these days that you didn’t realize before.

What Is a Thermal Scope?

Image of opmod IR imaging optic

A thermal scope is an electronic optics device that lets you see heat. The human eye can’t see infrared light, which is what heat is – we can only see whatever is on the visible light spectrum. 

What a thermal optic does is convert heat into visible light. (1)

What Do They Do?

Let’s break it down.

Thermal scopes see infrared light, but this can be broken into three groups: near, mid, and far. Heat, like the sort emitted by fire, is usually in the far-infrared range, which is where thermal scopes operate. (2)

The interior of the scope has electronics, lenses, and one lens coated with Germanium, a precious metal. When made very thin, Germanium is transparent and is able to sense infrared light, which is heat energy. 

Now, what the electronics inside does is convert this energy into something you can see. Traditional thermal optics show you a rainbow of colors for different temperatures:

  • Black, purple, and blue make up the colder parts of the image. 
  • Red, yellow, and white make up the hotter parts.

However, some scopes give you color palette choices. For example, the Pulsar Thermion 2 XP50 has an impressive number of eight different color settings

Most offer black hot or white hot – if you choose black as the hot image, then the cooler areas will be white, and vice versa.

Thermal rifle scopes take things a step further by providing a reticle for you to aim and shoot at targets. A number of scopes even come with multiple reticle choices.

IMPORTANT – Some thermal devices are temperature sensitive (which makes sense, they see heat sources). Most rifle scopes will work in temps below freezing to around 100 degrees Fahrenheit. Colder temps are better because the scope’s purpose is to detect heat and if it gets hot, it has a harder time working properly.

Bonus! Thermal scopes work during the day and in complete darkness. Traditional night vision, unfortunately, doesn’t work during the day because sunlight is too powerful for the internals. True night vision devices also require some kind of infrared illuminator in complete darkness.

What Does a Thermal Scope Look Like?

What a thermal scope looks like depends on what it’s used for. If you look at the largest in existence, you’ll see telescopes that peer into deep space. The dishes on these devices can be many yards across.

Getting back down to earth, a Computed tomography (CT) scanner is used in medical settings to examine a person’s internals. These are big enough for a person to fit inside. Medical folks also use small thermal scopes to check a person’s temperature. (3)

Now, public safety workers may use handheld thermal devices with a screen several inches across. These often look like a box with a handle. The bigger screen allows them to see more detail than small-screened devices.

For outdoor use, different shapes exist.

AGM Monocular

Some look like a rangefinder or something out of a science fiction movie. This AGM monocular is a thermal monocular and is not used with a gun, but instead, can be used to track something.

ATN Thor

Some look like a regular rifle scope with a few extras, like this ATN ThOR. The box in the middle houses the batteries, electronics, and recording ports. This one can record your hunts to be watched later from the comfort of your home.

AGM Rattler

Some look like a video camera, like this AGM Rattler (most thermal rifle scopes do allow you to capture videos of your hunt).

Echo3 Sig

While still rare, a red dot thermal scope exists. This Echo3 from Sig Sauer is the smallest of the thermal gun scopes and will fit on a rifle, shotgun, or handgun.

What Are the Most Common Uses for a Thermal Optic?

The most common use for thermal optics is in the broad category of safety imaging. You can break it down into these groups:

  • Medical field
  • Law enforcement
  • Firefighting
  • Utility companies
  • Building construction and inspection
  • Military
  • Hunting

Using thermal optics for hunting and the outdoors is a small but growing segment of the market. As more states open nighttime hunting opportunities, the market will grow and more manufacturers will start making these optics. 

A lot of the reason for the increase in hunting at night is due to wild hogs. These non-native critters cause huge amounts of damage to crops, and unfortunately, are smart and can quickly learn to avoid traps. If pressured, they’ll also shift to feeding at night.

Thermal Scopes and Hog Hunting

Of all of the above mentioned uses for IR optics, hunting is the most common for civilians, hog hunting in particular. If you’re a hunter, make sure to check out our article the top cheap thermal scopes for hog hunting.

How Does a Thermal Optic Work 

Thermal optics work by sensing the heat that comes off objects. 

Here’s an example:

Imagine a fire. You can see the flames, but not the heat that spreads away from the flames.

A thermal optic device will see the heat. It sees the flames as well, but as a different image than what you can see. The heat that comes off the fire will cover a much bigger area than the flames. This is what the thermal device sees.

Given time, heat can penetrate many substances, and a thermal camera will see this. You can touch a sheet of metal and it’ll absorb heat from your hand, and when you move your hand away, a thermal scope will “see” the residual heat left behind.

What Can You See With a Thermal Scope?

With a thermal scope, you can see heat signatures. This is why it’s used in the medical and public safety fields as the device can pinpoint hot spots not visible to the naked eye.

In hunting, this means you can see through rain, fog, and light brush.

However, you can’t see through glass, trees, metal, thicker plastic, or anything else that acts as an insulator.


What is a thermal dual power scope?

A thermal dual power scope is a fictional device used in Call of Duty. You cannot buy this for use in the real world.

Are thermal scopes real?

Absolutely, thermal scopes are real, and you can use them in most states. California is an outlier, but the state legislature recently made hog hunts much easier, so more relaxed rules could follow.


  1. NASA Science, Infrared Waves, retrieved from https://science.nasa.gov/ems/07_infraredwaves
  2. NASA, The Infrared Region, retrieved from https://www.nasa.gov/audience/forstudents/9-12/features/F_The_Infrared_Region.html
  3. US Department of Defense, Department Uses Thermal Imaging to Detect COVID-19, retrieved from https://www.defense.gov/News/News-Stories/Article/Article/2178320/department-uses-thermal-imaging-to-detect-covid-19/

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