Why is the lens of the red dot sight collimator tilted?

whether they are open red dots, such as RMR RED DOT SIGHT.

When we see all the red dot reflex sights on the market, whether they are open red dots, such as RMR RED DOT SIGHT.

Or the closed red dot, such as T2 RED DOT SIGHT,

whose glass is installed obliquely.

Many customer friends also ask this question.

Please rest assured that this is not a product quality defect, it is very normal. Because the red dot collimator needs a LED light source to illuminate the optical glass, and relies on the coating on the optical glass to reflect the red dot to your eyes. Please see the picture below for the principle.

Therefore, the glass of all red dot collimators is installed obliquely.