How Does a Red Dot Sight Work?

Red dot sights are an excellently innovative optic that is designed for use in close to moderate distances. Its value comes from its simplicity and use of clever technology to create an accurate optic that anyone can quickly acclimate to without needing to spend very much time on shooting practice.

There’s more to it than that, though. The red dot sight has many benefits that make it as popular as it is. When you get an optic as versatile and straightforward as this, you can’t help but wonder what makes it tick.

So how does a red dot sight work? Below, we’ll be looking at the answer to this and why they are so popular and easy to use.

Origins of the Red Dot Sight

Newcomers are always surprised to find out that there is very little new technology in modern firearms. Red dot sights are by no means a new or recent invention, with their roots tracing back to over a hundred years ago. However, the red dot sight as we know it today has only been around since the mid-1970s.

Red dot sights are reflex sights, or more accurately, a more modern rendition of the reflex sight. Reflex sights have been used historically on rifles and snipers to provide an optic that is easy to use and that is reliable without the necessary hassle of operating and maintaining a scope.

The idea behind the reflex sight was to take in light from a small window on the top that would shine on a piece of reflective glass that lay at an angle inside the optic. This would essentially allow an image to be reflected inside the sight to create an image projected to what was effectively infinity. This would enable quick, accurate shots that were easier to pull off on smaller firearms, hence the term “reflex” sight.

The result used light that was reflected through a concave piece of glass to create small and simple shapes that would be used as reticles for easier aiming. The cost of this was a sacrifice in magnification, so reflex sights would not be suitable for any kind of long-distance shooting.

That was back then, though, and the reflex sight has seen much overhauling and experimenting. We now see many different types of reflex sights that still use the same concept of reflected light through a curved lens to create a projected image. The red dot sight is one such reflex sight, and as we have mentioned before, it is relatively recent in its innovation compared to most items in the firearm industry.

Now that we have an idea of the history of the red dot and the reflex sight’s core design, we can look at how that idea has been updated using modern technology, as well as exactly how the contemporary reflex sight works.

The Red Dot Sight – A Modern Reflex Sight

The red dot sight we see nowadays isn’t that different from the old design, but it does incorporate new technologies that didn’t exist back then. Over the years, many other optics have come about from that initial design, and anyone who plays modern first-person shooter games probably has an idea of some of them.

The red dot sight, in particular, is uniquely simple in its design. Using two curved lenses in the optic, one in front and the other in the back, you can create a tube of sorts for light to travel through. Some of the smaller sights have these two lenses close together, such as on pistols, but the distance doesn’t necessarily matter.

From this point, there are two different avenues that manufacturers can take. They can develop a passive system that is powered solely by light or an active system with an actual power source built into it.

To put it simply, passive systems have images of the reticle etched into the two reflective lenses’ glass. These images are usually made from a different reflective material, copper being a common option, and are typically placed either at the focal point of the front lens or at an angle inside the scope housing.

With angled placements, the angled lens will project and magnify the image onto the focal point of the front lens. The glass lenses are also often treated to only let red light through, thus creating the red dot effect, but there are red dot sights with different colors, such as green or cyan.

Active systems are passive systems that don’t need to rely on external light sources, as there is a lighting system built into them so that you’ll always have light handy. LEDs are used because they shine brightly so that you can easily distinguish the sight from the target on the other end of the reticle.

Thus, when light enters the optic or scope, the image etched into the lens will illuminate and magnify thanks to the curved lenses. This makes the tiny reticle appear much larger thanks to a simple magician’s trick from years ago.

In short, the light goes in, is reflected around inside the optic, and the reticle lights up for aiming.

Different Types of Red Dot Sights

A few different variants of the red dot sight use the same technology to varying degrees for different effects.

Standard rifle optics are the most common variety of red dot sight and can be considered a benchmark or baseline. They are often a 2 or 3 MOA red dot that is for more moderate to close ranges. The larger the dot is, the easier it is to spot on the reticle and the faster you can train it on the target.

Miniature red dots are tiny and are for smaller firearms, such as pistols. These red dots are mostly used for pistols and as backup rifle sights, and they are characterized by their dot being significantly smaller than others. Because of their smaller reticle, it’s far easier to spot the target, but it can be more challenging to spot the dot on your reticle, so you may have some difficulty training your dog on the target initially.


Red dot sights are continually being upgraded and updated, but they are by no means a new invention. Their roots go even further back than the 1970s when they were first used. They are a wonderfully simple design that is an excellent choice for anyone looking for an easy-to-use optic in close to moderate ranges.

If you aren't familiar with the gun safes on the market and you aren't sure which of the gun safe models is the best choice for you, I recommend you to read my Gun Safe Buying Guide so you can learn how to determine which gun safe suits your lifestyle best. I have made a detailed guide about the features you have to consider before you buy a gun safe and they are connected to the size, brand which made it, capacity, materials used during the production and special features like fire or water protection. If you are familiar with all those features, I suggest you visit my posts about best biometric, quick access or fireproof gun safes if you know that they suit your lifestyle best.