Prepper's Armory: Reflector Sight

The ancestor of the modern red dot sight family is the reflex sight, originally called a reflector sight. It's been around for considerably longer than most people realize: the reflector sight was originally patented in 1900 by Sir Howard Grubb, a noted optical designer and telescope maker in Ireland. He titled his patent "A Gun Sight for large and small Ordnance" and described it as "a better alternative to the difficult to use iron sight while avoiding the telescopic sight's limited field of view, greater apparent target speed, parallax errors, and the danger of keeping the eye against an eye stop."

Early Reflector Sight

On March 20th 1901, at a meeting of the Royal Dublin Society, Sir Howard began the explanation of his new invention as follows:

When it is necessary to point any instrument at an object, whether it be a rifle, or a gun, or a telescope, it is usual to do so by glancing at the object along the axis of the instrument, or some member or part which is parallel to the axis, bringing this part as nearly as possible into line the of sight between the eye and the object aimed at. This is done instinctively, without any education or instruction, and it is curious to note that in this, the twentieth century, the most primitive and unscientific method still endures, and is used in all but exceptional cases for sighting purposes in our most modern weapons.

He continued by describing a theoretical sight we may also recognize:

It would be possible to conceive an arrangement by which a fine beam of light like that from a search light would be projected from a gun in the direction of its axis and so adjusted as to correspond with the line of fire so that wherever the beam of light impinged upon an object the shot would hit. This arrangement would be of course equally impracticable for obvious reasons but it is instanced to show that a beam of light has the necessary qualifications for our purposes.

Now the sight which forms the subject of this Paper attains a similar result not by projecting an actual spot of light or an image on the object but by projecting what is called in optical language a virtual image upon it.

Impossible then, but he quite clearly described a laser sight of the type most Americans became familiar with in the mid-1980s.

He went on to detail what most shooters of today would instantly recognize as a reflex sight, and listed a number of features we expect from the modern iterations of his invention.

Modern Reflex Sight

These points included:

1. The aiming mark being sharply defined simultaneously with the object being aimed at, meaning that the shooter could keep both the aiming mark and the target in focus simultaneously.
2. Little to no parallax. As long as the aiming mark and the target were both visible, the bullet would impact where they coincided.
3. The ability to be used with or without magnification.
4. Any form of aiming mark, whether cross, circle, or other, could be used, even those impossible in traditional magnified optics of the time.
5. His design was self-contained and easily detachable from the weapon.
6. The sight itself has no adjustments, so it is not possible to be put out of order or adjustment unless actually broken.
7. The field of view is practically unlimited and the view of the horizon is not obstructed.
8. The aiming mark can be conveniently illuminated and the sight used as effectively at night as in the day.

Sir Howard's invention was slow to catch on at first, but soon went on to take the world by storm. It was first adopted into military service on German fighter planes late in World War One, followed by use on nearly every other military aircraft of the 1920s and 30s. By the Second World War, the reflector sight was being used not just in aircraft gunsights but on a wide variety of military equipment, including land, vehicle mounted, and naval artillery. 

Its simplicity and quick target acquisition let to the adoption of the name "reflex sight" that we still use to this day.