Peilitähtäin

Peilitähtäin, also known as a reflex sight or red dot sight, is an optical sight that allows the user to see through a transparent reflecting surface and a reticle (often a red dot) illuminated from behind. The reticle is projected onto the optical element, appearing to the user at the same distance as the target. This design eliminates the need for the user to focus on separate front and rear sights, allowing for faster target acquisition and improved accuracy, especially when moving.

The fundamental principle of a peilitähtäin involves a light source, typically an LED, projecting a reticle pattern onto a lens or mirror. This reticle then reflects off a combiner lens, which is also transparent to the user's view of the target. The user sees both the target and the reticle superimposed in the same focal plane. Many peilitähtäimet are adjustable for brightness and windage/elevation to ensure precise aiming. They are commonly used on firearms, airsoft guns, and crossbows due to their ease of use and effectiveness. Variations exist, including holographic sights which use lasers and holograms to project the reticle, offering a wider field of view and parallax-free aiming.