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Red
Dot Sight, also known as reflex sights or infinity sight, are
the technology-of-the-day. Red
Dot sight uses fiber optics, LED's, or Tritium to create a red
dot inside the rifle or pistol scope. The dot looks like it is on
the target, but it is visible only to the shooter. Where the dot shows,
the bullet goes. Reflex sights out-perform laser sights under well-lit
conditions.
How Red Dot Sight works
Red
Dot sights use a refractive or reflective lens to generate a collimated
image of a luminous or reflective reticle.
This collimated image appears to be projected out to a point at infinity,
which makes the image of the reticle
appear to the user to be projected onto the target. Due to the fact
that the reticle image is collimated,
magnifying the image of the target is impractical, as it would make
the sight too hard to hold steady. The collimated image does have
its advantages, however, as the scope can be placed at any distance
from the eye without distorting the
image of the target or reticle. This
makes red dot
sights suitable for use on pistols, rifles, or shotguns. The lack
of magnification is also an advantage
in that both eyes can be left open, and the eye that sees the reticle
image will automatically superimpose that image with the image from
the other eye, giving the shooter normal depth perception and full
field of view. This makes the red
dot sight very fast and easy to use.
Types of Red
Dot Sights
Some of the first red
dot sights to appear were "occluded" sights; the image of the
target was not visible through the sight. Looking into the sight with
just one eye, the shooter saw only red dot. With both eyes open, the
image of the dot was superimposed by the brain onto the target. Nearly
all currently available red
dot sights use a curved partially reflective glass as a lens.
This lens allows light from the target to pass through unobstructed,
but collimates and reflects the light of the reticle
back to the shooter's eye, thus allowing for one- or two-eyed aiming.
Modern red dot
sights generally fall into two categories:
- Full tube - looks similar to a standard telescopic
sight, with a cylindrical tube containing the optics. Since a red
dot only really needs a single reflective surface, however, the tube
is not needed. Many current designs consist of a flat base, with a
single loop of material to support the reflective surface. While some
argue that the open design gives the shooter a wider field
of view, the actual viewable range of the dot is no larger than
a full tube sight.
- Open designs - usually lighter than a full tube sight, since less material is required. More expensive full tube sights offer the option of polarizing filters and glare reducing sunshades, which are not possible on opens sights.
What is Red
Dot Sight used for?
Red
Dot sights are common in speed shooting sports such as IPSC. Militaries
are also beginning to adopt Red
Dot sights, since they are easy and fast to use, and since the
dot sights work very well in low light conditions. Most dot sights
have either active or passive adjustments for the dot brightness,
allowing a very bright dot for high visibility in bright conditions,
and a very dim dot to prevent loss of night vision in low light conditions.
Since dot sights
can be mounted at any distance from the shooter's eye with no issues
of focus, military rifle mounts usually place the sight over the forend,
about 12 inches (30 cm) from the shooter's eyes. This leaves plenty
of room for night vision equipment
to be used with the night vision sight.
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