How Red Dot Sights Work (What is a Collimator?)

Published on January 16, 2026
Duration: 8:14

This video, presented by Ian McCollum of Forgotten Weapons, provides an expert-level overview of how red dot sights work, tracing their lineage from early WWI collimating optics to modern LED-based systems. It details the principles behind collimation and examines key historical examples like the Nydar scope, Armson OEG, Weaver Quick Point, and Aimpoint Electronic Mark 2, highlighting their technological advancements and limitations.

Quick Summary

Red dot sights evolved from WWI collimating optics, which use a special lens to create a parallel light beam projecting a reticle at infinity. Early examples like the Nydar scope used ambient light, while the Armson OEG and Weaver Quick Point utilized fiber optics. The Aimpoint Electronic Mark 2 pioneered battery-powered LEDs, enabling consistent visibility in all lighting conditions.

Chapters

  1. 00:00Introduction to Collimating Optics
  2. 00:58How Collimators Work
  3. 03:38The Nydar Scope
  4. 04:45Armson OEG (Occluded Eye Gunsight)
  5. 06:30Weaver Quick Point
  6. 07:28Aimpoint Electronic

Frequently Asked Questions

What is a collimator in the context of firearm sights?

A collimator is a specialized lens that takes light from a source and refracts it into a parallel beam. When used in a firearm sight, this creates a reticle that appears to be projected at infinity, providing a consistent aiming point that doesn't shift with the shooter's eye position.

How did early red dot sights like the Nydar scope function?

The Nydar scope, an early small-arms application of collimating optics from the 1940s, used ambient light reflected through a lens to project a bullseye reticle. However, it was limited by its dimness in low light or against bright backgrounds.

What is the 'occluded eye' principle used in sights like the Armson OEG?

The 'occluded eye' principle means the shooter doesn't look directly through the sight. Instead, the reticle is projected into the shooter's field of vision, and their brain superimposes this red dot onto the target seen by their other eye.

How did the Aimpoint Electronic Mark 2 differ from earlier red dot sights?

The Aimpoint Electronic Mark 2 represented a major advancement by using a battery-powered LED to generate the reticle's illumination. This made the sight visible in total darkness, overcoming the limitations of earlier designs that relied on ambient light or fiber optics.

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