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Green laser in 4x4/rally use

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tsk1979

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I work with 4x4 and rally teams. Sometimes, a vehicle breaks down in middle of nowhere, and even with GPS coordinates, it can be tough finding it.
I am wondering, in the nightime, will a 20mw Green laser to be shined straight upward by the driver of the vehicle will act as a nice beacon?
I see lot of burning lasers for 15-20$ at aliexpress... but
1. They use 16340 or 18640 batteries. I need something which uses AA or AAA
2. They burn. I do not want something so powerful. Just something with a fixed focus and
3. After 3-4 months, they go bad. So quality is paramount.

Is it possible to get a 20mw Greenie which is reliable, can be kept on continously, and does not drain out the batteries quickly for 20-25$

If its possible, I do not mind buying 10-15 of these for the teams if they are interested.
 





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tsk1979

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This is excellent
I think their 20mW is actually 30mW from the chart.
50mW will approach burning category.

For visibility around nautical twilight, 20mW one should be enough, right?
 
NightExplorer96

NightExplorer96

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tsk1979 said:
This is excellent
I think their 20mW is actually 30mW from the chart.
50mW will approach burning category.

For visibility around nautical twilight, 20mW one should be enough, right?
Click to expand...

Um...beginning or end of nautical twilight? If it's the beginning 50mW would be better.


Edit: Which resembles most what conditions the laser will be used in?

Beginning of nautical twilight
9097-nautical-begin.png


Middle of nautical twilight
9098-nautical-middle.png


End of nautical twilight
9099-nautical-end.png
 
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CheeseHasLeafs

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How do you plan to use this exactly?
I'm assuming it would be together with the GPS, which means that the laser has got to be visible within about a thirty metre radius?
DPSS green lasers have beams that can be needle thin, and visibility of the beam decreases as your viewing angle widens.
Maybe a better thing to use would be a rotating light mounted on a pole of some sort?
 
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trencheel303

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20mW won't be enough . You need something beefier so it can catch the eye even when being aimed straight upwards.

You need to be looking at 50-100mW before you get a beam that will draw enough attention.

... and by catch the eye I mean draw your attention to it even from peripheral vision. Not shining in eye.
 
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Tmack

Tmack

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It takes a fair amount if power to be able to view a beam pointing straight up from the side. I would say way more than 100mw.

Next time try to have someone else point a 100 mw straight up, walk 50ft, and see if you can still see it. If so it will be very dim. Then try 100ft. Gone .....

You'd have to rotate the laser 360degrees at a 45 degree angle so you'd maximize visibility for a distant onlooker.
 
Livinloud

Livinloud

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I agree, laser beams are only very visible when looking at them head on or from behind. Viewing from the side doesnt really allow you to see the beam; seems odd seeing how they are so visible from behind but its the truth
 
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trencheel303

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Tmack said:
It takes a fair amount if power to be able to view a beam pointing straight up from the side. I would say way more than 100mw.

Next time try to have someone else point a 100 mw straight up, walk 50ft, and see if you can still see it. If so it will be very dim. Then try 100ft. Gone .....

You'd have to rotate the laser 360degrees at a 45 degree angle so you'd maximize visibility for a distant onlooker.
Click to expand...

let them buy 1.6 Watt laserbtb 445s then :gun:

pretty sure when i shone mine in the sky the whole town shat themselves :na::eg:
 
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Tmack

Tmack

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Thejoker301 has a video of a 2.2w that's visible from miles away.

But it was being rotated. Even a 3w will look dim straight up from not as far as you'd think, but add a light angle toward you, and it makes a huge difference.
 
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trencheel303

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Well that's consoling, but I will probably test it with my own eyes before shining the laser much outside again. I'd rather it in my house than that of a police :shhh:
 
Javalin

Javalin

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I live in an apartment building. I had a 50mW green pen, I told (asked) my girlfriend to stand on the balcony while I stood on the 10th floor (she was on the 23rd floor) I stood as far back as I could (about 12 meters) and pointed it straight up. She couldn't see the beam at all looking straight out and couldn't until I was about 3 meters away! They make laser type emergency beacons, but even those have to be pointed toward the rescue team, not up in the air.
 
Livinloud

Livinloud

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Keep an eye out around 10 seconds when the beam disappears, that is since its shining straight up. When shining towards the camera, even at 15 degree angle, it can been seen. You also see how you'd risk having the beam shown directly in your eyes and go blind.

 
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