Why are red dots red?


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Frye
June 24, 2013, 06:36 PM
Just curious as to why Aimpoint and EOTech optics are always 'red dots'. For comparison if a green laser is much more visible compared to a red laser based on the way our eyes perceive color, why don't they have Green Dots sights?

I know there's some cheap red dots that allow you to change the colors but that always seemed more like a gimmick than a feature.

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Bovice
June 24, 2013, 06:41 PM
Red has the largest wavelength, it's been awhile since I studied optics but I think it has to do with being easier to see in all lighting conditions/from a distance.

firesky101
June 24, 2013, 06:43 PM
I have also heard battery life is significantly greater with red.

Bianchi?
June 24, 2013, 06:56 PM
High contrast on target. Red isn't a very prevalent color in nature, and shows up clearly against green and brown.

Deus Machina
June 24, 2013, 06:58 PM
Also, originally it was because of the available technology and materials.
Those $5 laser pointers? All red. Back when they were $100? Also red.
It's because the red laser was the only visible one they could make at a reasonable price at the time.
Now, I'm sure it comes down to price (they're still the cheapest), contrast, and because that's just what they've always done.

JustinJ
June 24, 2013, 07:28 PM
Other colors in lasers also tend to be less energy efficient and thus less battery life.

Bartholomew Roberts
June 24, 2013, 07:56 PM
Contrast is important for being able to aim and acquire a target quickly. Red offers contrast with a wide, wide range of targets. Some of the newer green reticles do a suprisingly good job of contrast while also being eye catching; but they tend to be more expensive to do right (though I don't know why that is).

Look at the TA01NSN reticle as a great example. Because the powers that be had determined the human eye picks up amber better than other colors, they made the reticle amber; but on a planet lit by an amber sun with a lot of browns, tans, and yellows, the reticle (illuminated only by tritium) would sometimes illuminate just brightly enough to wash out the reticle completely against the background - especially at dawn or dusk.

Reloadron
June 24, 2013, 08:19 PM
I believe Deus Machina pretty much nailed it as well as others. Red LASER diodes are cheap, real cheap with their cost dropping like a rock over the years. Give this link a read (http://repairfaq.ece.drexel.edu/sam/laserdio.htm#diodlm2a). I believe it covers it well. Also yes, battery life is also a key player in the equation.

Ron

Rule3
June 24, 2013, 08:31 PM
For someone with red green color blindness ( not completely but enough to fail a test) their choice of colors suks:D I can seen green dot optics much better. Red is invisible to me during the daylight. I vote for orange or bright yellow.:)

I have fiber optic sites on some handguns, red might as well be black but the green really glows in the sunlight.

22-rimfire
June 25, 2013, 12:14 AM
Color blindness.... that is an interesting addition to the discussion. Many people are slightly blue-green color blind but full color blindness is not common where everything is shades of grey.

Queen_of_Thunder
June 25, 2013, 12:30 AM
Just curious as to why Aimpoint and EOTech optics are always 'red dots'. For comparison if a green laser is much more visible compared to a red laser based on the way our eyes perceive color, why don't they have Green Dots sights?

I know there's some cheap red dots that allow you to change the colors but that always seemed more like a gimmick than a feature.
Ok I'll play this game. Why are red dots red? Because if they were blue they would be blue dots.

hso
June 25, 2013, 12:41 AM
Deus Machina is correct.

After the ruby laser and the gallium-arsenide laser, the red diode laser was the first "inexpensive" laser diode (and stayed so).

JohnBT
June 25, 2013, 08:51 AM
"Many people are slightly blue-green color blind"

99% of all colorblind/colordeficient people have red-green color deficiency.

Iirc, an article in American Rifleman said that the green lasers were 10x more expensive than the red.

aarondhgraham
June 25, 2013, 10:22 AM
My red-dot has three colors,,,
Red, green, & blue.

It's this one from Cabela's (http://www.cabelas.com/product/Shooting/Optics/Red-Dots-Lasers%7C/pc/104792580/c/104752080/sc/104526180/BSA-Optics-30mm-5-MOA-Dot-Sight/752242.uts?destination=%2Fcatalog%2Fbrowse%2Fred-dots-lasers%2F_%2FN-1100252%2FNs-MIN_SALE_PRICE%3FWTz_l%3DSBC%253BMMcat104792580%253Bcat104752080%26WTz_stype%3DGNU).

Aarond

.

Willie Sutton
June 25, 2013, 10:49 AM
Should I point out that a minority of "red-dot type sights" use a laser as opposed to a LED? Your cheap <fill in the brand name> multi-color "dot" is not using a laser.


Willie


.

ljnowell
June 25, 2013, 10:54 AM
They do have green dot sights. I use one every tuesday in my bullseye league.

JustinJ
June 25, 2013, 11:41 AM
My red-dot has three colors,,,
Red, green, & blue.

I believe that is because it is not a holographic site which uses a laser. To my knowledge red and green are the only practical options for holographic sights with laser diodes. The latter being harder to implement due to size and energy requirements. In fact, green laser diodes don't actually exist but instead an IR laser must be converted to green. The article below explains this well:

http://www.americanrifleman.org/articles/going-green-with-lasers/

brickeyee
June 25, 2013, 12:40 PM
Green uses an IR laser that is then frequency doubled up into the visible spectrum at green.

It is a lot more complicated, and uses a lot more power for the same optical output power (though the human eye is generally a lot more sensitive to green).

The 'color change' is not 100% efficient.
Unless filtered, there is still a bunch of IR coming out.

Frye
June 25, 2013, 12:44 PM
All excellent points. Thanks for the explanations.

I just ordered an Aimpoint PRO and it just kinda made me wonder why they are mostly always 'red dots'.

On that note, does the Aimpoint use and LED or a laser as some have mentioned? Is it just EOTech that uses a laser?

The point of contrast is excellent. Red is opposite of green on the color wheel so ergo it's hypothetically the best for pickin up against a green (forest) backdrop. Though it would seem those over in the sandbox would get a lot of benefit from a purple reticle according to that logic.

It would be interesting if future optics could automatically adjust brightness, color, & whatever else you may need to suit your environment. And then it's always a matter of personal oppinion which is best so it could make the whole argument subjective.

JustinJ
June 25, 2013, 01:10 PM
I just ordered an Aimpoint PRO and it just kinda made me wonder why they are mostly always 'red dots'.

On that note, does the Aimpoint use and LED or a laser as some have mentioned? Is it just EOTech that uses a laser?

According to their site, they use an LED rather than a laser diode. I guess that makes sense given their battery life. In that case i would expect they should be able to make other colors easily.

mac66
June 25, 2013, 01:38 PM
I have a cheap dot sight that has red, green and blue dots. IMO the red is easier to see and I prefer it.

ThePenguinKnight
June 25, 2013, 04:28 PM
Are there any dot sights (of any color) that use a real laser diode instead of an LED?

GrOuNd_ZeRo
June 25, 2013, 04:45 PM
I was always under the impression regular Light Emitting Diodes (LEDs) were used oposed to Laser diodes, lasers seem harmful to eyesight IMO but I could be wrong since they are reflected rather than directly aimed at the eye.

Amber is used in many tritium sights in the military such as gunner's sights (Howitzers/Tanks) and green in Heads-Up Displays (HUDs) in aircraft.

JustinJ
June 25, 2013, 05:31 PM
I was always under the impression regular Light Emitting Diodes (LEDs) were used oposed to Laser diodes, lasers seem harmful to eyesight IMO but I could be wrong since they are reflected rather than directly aimed at the eye.

I know my eotechs had warning labels about laser radiation. Also: http://www.eotech-inc.com/making-a-hologram

Deus Machina
June 25, 2013, 05:34 PM
The cheaper ones may use LED's and you're only seeing a reflection of the spot of light.
More expensive ones use an actual laser, which makes for a more directed, clearer dot.

Reloadron
June 25, 2013, 07:40 PM
First of all you can get dots in any color you want as can be plainly seen:

http://bearblain.com/images/Dots.png

Now looking back at the original post maybe some clarifications are in order:

Why are red dots red?
Just curious as to why Aimpoint and EOTech optics are always 'red dots'. For comparison if a green laser is much more visible compared to a red laser based on the way our eyes perceive color, why don't they have Green Dots sights?

I know there's some cheap red dots that allow you to change the colors but that always seemed more like a gimmick than a feature.

When we look at Aimpoint for example and look at what Aimpoint has to say:

Worldwide leader and originator of red dot sights also called reflex sights.
AimpointŪ is the recognized worldwide leader and originator of the red dot sighting technology.

That Reflex part is important.

A red dot sight is a common classification[1] for a type of non-magnifying reflector (or reflex) sight for firearms that gives the user an aimpoint in the form of an illuminated red dot. A standard design uses a red light-emitting diode (LED) at the focus of collimating optics which generates a dot style illuminated reticle that stays in alignment with the weapon the sight is attached to regardless of eye position (nearly parallax free). They are considered to be fast acquisition and easy to use gun sights for target shooting, hunting, and in police and military applications.

Note at this point there is no mention of a LASER, only the lowly LED (Light Emitting Diode). The LED is merely a light source within the optics. The above quote was taken from here. (http://en.wikipedia.org/wiki/Red_dot_sight) The link is worth a read to understand how these animals work. Why Red? Considering that a Red, Green. Blue or Yellow LED have little difference in cost (the common red is less expensive) a Red LED does have less current draw on the battery and considering most optics like this use small coin cell batteries my guess is battery life is a prime consideration.

LASER sighting systems are a totally different animal. LASER systems actually project a beam of light on the target, just like LASER pointers. Movie makers love these things. The bad guy looking down as a LASER dot sits on his body freaks them out. Pretty cool as where that spot is will be the point of impact of the bullet. Not that you can see a LASER spot between your eyes but you get the idea.

Today's red low power LASER beams are created by LASER diodes not to be confused LEDs which are different animals. Red LASER diodes are cheap, green LASER diodes are not so cheap. It becomes a matter of how the light is created. I gave a link in an earlier post covering that.

Anyway, red dot scopes as we call them are not LASER optics. Aimpoint optics do not use a LASER system. They use a red LED as a light source. The most logical for the choice of red is likely battery life in my opinion. Beyond current draw colors other than red, orange and yellow typically have higher working voltages adding to battery configuration problems.

Just My Take
Ron

benEzra
June 25, 2013, 07:53 PM
Just to clarify, the Eotech uses a red diode laser and a diffraction grating to create a hologram of a red ring and diffraction-limited center dot in the window. The Aimpoint and other dot-type reflex sights use LED's, as described.

JustinJ
June 25, 2013, 07:57 PM
Anyway, red dot scopes as we call them are not LASER optics. Aimpoint optics do not use a LASER system. They use a red LED as a light source. The most logical for the choice of red is likely battery life in my opinion. Beyond current draw colors other than red, orange and yellow typically have higher working voltages adding to battery configuration problems.

That's not actually completely true. The Eotech, per the link I posted, does actually use a laser to create a holographic image for use as a reticle.

I wonder though if part of the reason red is so commonly used in red dot scopes does not have to do with the fact that laser sighting systems were all also initially red. Really though I think it probably has most to do with the ability of the eye to quickly pick up red against most commonly encountered targets.

JohnBT
June 25, 2013, 10:39 PM
Somebody's eye, not mine. Red sux.

-v-
June 25, 2013, 11:33 PM
Always assumed its because red diodes and lasers use the least power out of the spectrum, thus giving these weapon sights the longest possible battery life.

e3mrk
June 25, 2013, 11:35 PM
Because it has a Red Light.

Reloadron
June 26, 2013, 07:22 AM
Just to clarify, the Eotech uses a red diode laser and a diffraction grating to create a hologram of a red ring and diffraction-limited center dot in the window. The Aimpoint and other dot-type reflex sights use LED's, as described.
My bad as I only focused on Aimpoint. Thank you all for pointing out Eotech uses a different method using a LASER.

Thanks
Ron

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