Red dot sight

Introduction

Red dot sight is a reflector sight with no magnification.

Collimator sight.

Theory

Spherical partially reflecting mirror.

Parallax free only at infinity.

Optical system can be made to compensate for off axis spherical aberration.

References

https://en.wikipedia.org/wiki/Red_dot_sight

https://www.chuckhawks.com/optical_sights.htm