Red dot emitter: open vs enclosed

If you ever considered buying a red dot for your gun, you surely ran into these two types of red dots:

red dots with enclosed emitter, and
red dots with open emitter.

How do they differ?

Red dot with enclosed and open emitter - compared — Red dot with open emitter on the left side, red dot with enclosed emitter on the right side. You can notice the protection glass on the red dot with enclosed emitter.

Key difference: open vs enclosed emitter

These two types differ whether or not the red dot emitter is situated behind protective glass:

if the emitter (source of the laser dot) sits behind glass, it is red dot with enclosed emitter,
if the emitter sits in the open and you can reach it, it is open emitter.

That is the key technical difference. That by itself however does not make the selection any easier for you. So lets get to the consequences of each solution

Enclosed emitter: pros and cons

Because of the double glass, the body of red dots with enclosed emitter is usually larger and take more space. Despite that, the aiming window is usually smaller and as a result less convenient for sport shooting.

The emitter is situated behind the glass, it cannot be reached.

The positive consequence is that the emitter is well protected against rain, dirt or snow, or whatever may come to the red dot. For sport shooters it is not often something to think of, but for self defense purposes it can be very important – the dot will be working in whatever conditions.

Because of the larger and more sturdy construction, the red dots with enclosed emitters are usually also more expensive.

Summary [enclosed]:

+ protection against rain, snow, mud
+ the red dot functions in all conditions
– higher price
– smaller window = slower target acquisition
– larger construction

Osight SE - red dot with enclosed emitter — Osight SE – red dot with enclosed emitter within the middle price range

Open emitter: pros and cons

Red dots with open emitter are much more common and popular, because for sport shooting it is more ideal, unless you shoot in snowstorm. Because once something gets between the dot projector, and the glass on which it projects, then you have to clean it. Otherwise you will not see the red dot, and will not be able to aim with it. Or at least the dot will not be visible well.

However, do not be afraid of somehow damaging the emitter yourself. Within the range shooting you will not make the emitter dirty or not work.

Here the emitter is in the open space, easily approchable.

On the positive side, the red dot with open emitter usually has larger window – because it is not closed from both sides – which leads to faster finding of the target.

These red dots are also less large and robust. The price tag of these red dots is also slightly lower compared to the enclosed red dots.

Summary [enclosed]:

+ larger window = faster target acquisition
+ lighter and less robust construction
+ usually cheaper compared to enclosed red dots
– not protected against rain, snow, etc
– the red dot can stop working in bad external conditions