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Sharp 490nm GH04850B2G 55mW Laser Diode

RedCowboy

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It depends on the time of day and the humidity, also the angle and distance.

You could at your own risk try safely walking around your back yard with the laser secured and safely terminated and look at how visible it is from variable distances and angles, notice the intensity of the visible lens flare with and without a shroud.

A beam looks the brightest coming at you, 2nd brightest going away from you, from the side it fades fast, but lens flare stands out from a wide angle and fairly long distance even when a beam may not be visible, see rayleigh scattering.

p.s. If a car drives by or person walks by I stop lasing, actually as soon as I hear a car before I even see it I stop unless I am in my backyard and not in line of sight of the street or pointing to the ground with my back to the street, but always be aware of your ability to create a distraction be it intentionally or not, you are better off simply not drawing attention, drawing attention is distracting and could put you in the wrong.

The worst case would be pointing across the street ( empty street ) at a tree line when an approaching car sees not your beam but lens flare and being novice the observer thinks you have targeted them, even though you stopped lasing before they passed under your beam, this is where a flare hider buys you time as modest power beam disappear from the side over a short distance, but lens flare stands out for a long way and in every direction that it's in line of sight.

I am not advocating anything illegal or dangerous, just suggesting we hide our lens flare to avoid unintended distractions.
 
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Alaskan

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I've never seen a laser beam coming at me and then comparing what it looks like going away to know that, interesting.
 

RedCowboy

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Have you ever safely bounced a beam off a mirror, you have seen how it looks brighter coming back.

By safely I mean setting it up with safety glasses on then observing it secured.
 
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RedCowboy

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It's best outside where you can walk downrange and see how bright your SECURED beam looks coming towards you ( SAFELY ) or in a fairly dark room and/or with fog.

Here's an old pic that even my cam picked up the difference, notice how the returning beams in the fog appear brighter. The lasers are on the left and the rebound is on the right. There's also an interesting reflection of the effect seen in the mirror.

 

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Alaskan

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Thanks RCB, now I can see what you mean, for the beam to be that much brighter on the exit, the pointer would probably need to be multiples more powerful, it really makes a big difference.
 

RedCowboy

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I have noticed before when I have a 100mw 532 clamped down at my back window and terminated in my yard that when I go outside and stand under/beside it, WOW, it looks significantly brighter coming towards me.

It was a wet night, but this little red 650nm would never look this bright except coming towards me. It was terminated upon the telephone pole behind me and there was no traffic.



Anyway about the sharp 490.

Here in this pic of my 490 next to a 532 did you see my spectator ?
Grey kitty with white bib, they must have looked pretty bright from down there, LOL Kitty was 100% unharmed.

 

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paul1598419

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I noticed this effect years ago taking beam shots indoors. In fact, I often took beam shots going both ways. Away from my camera and then toward it.
 

RedCowboy

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The neat thing about the mirror is how the beams going away from my eye and my camera are dimmer on the left, but brighter in the mirrors reflection on the left as it should be, because those beams are brighter on the mirrors side, and vise versa on the right side, what's cool is how they come together at the reflection point and give the illusion of traveling straight through.

 

paul1598419

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I just finished building a 486.9nm one of these with a Nano Boost driver set to 278 mA. It is definitely very blue. Looks the same as my 488nm agron, only brighter. I have it paired with an acrylic lens and it has no artifact that I can see at all. If you are going to do a build with one of these at this current the copper module gets quite warm within 30 seconds. If you put it into a pen, I would limit the run time to that 30 seconds. But, if you heat sink it, it should be good for much longer run times. :yh:
 
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BowtieGuy

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That sounds good, Paul, I think that's about the range that I'm going to aim for when I get mine.
It's kind of nice to be able to use the stock acrylic lenses for these lower powered diodes and get good beam specs.
Do you have any pics of your new build yet?
 
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paul1598419

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No, Jeff. I am putting these together for ZRaffletiket as he has had issues in the past with losing diodes and drivers to mistakes. I have done so many I can almost do one in my sleep. You are going to love the one that is going to you as it should be the same color.
 




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