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Emerald dust fireflies many twinkling dots DIY?

sbright33

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BlissLights Spright - Amazon.com

What kind of diffraction gratings does this require? 2 of em?
Where can I purchase them? Ebay? Cost?

Is there another method to generate many 100's of beams from 1?
How about just 10 randomly XY spaced dots?

Which method is most efficient for power output?

Been building lasers since 1983. My first Post! Thanks in advance,
Steve
 

sbright33

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I've got many lasers. Will it look sorta random or a distinct repeating pattern like wallpaper in the bathroom? How can I make it more random like stars in the sky? Moving of course. Mechanically how do I rotate both? Thanks for the quick reply!
 

MarioMaster

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It won't really be random, you get the effect because you're mixing two gratings which causes the second grating to split up the beams made by the first one. When you rotate one the dots combine and split apart, but they will always be the same distance apart in the same pattern as that's how the diffraction grating is made.

To get random individual points you will need some more complex optics or perhaps a galvanometer system like from a lasershow.
 

BShanahan14rulz

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Perhaps the more gratings you add, the more random you can get it to look. I kind of wonder if the randomness in the amazon photos is just the nature of the subject that the light is shining on, although it is still hard to find a pattern on the garage door.
 

sbright33

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That's exactly what I'm trying to figure out! How do they do the garage door so randomly?
 

sbright33

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Those are definitely not random looking. But can I replace the laser inside?
 

Javalin

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I've sent a beam through two gratings and if it only off set by a tiny bit the effect looks very similar to the one in the picture. I'll see about getting a picture of it tonight.
 

Javalin

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Sorry everyone that it's taken me so long to get these pictures. I was trying to figure out a better way to capture what it would look like being thrown on a house. I live in an apartment so the best I could do is throw it on the wall at about 5ft and have my girlfriend stand next to it for size comparison.

As I played with the different diffraction gratings I got a few pictures to show how dramatic a difference small changes make. Even the order in which you put the gratings.

Huge shout out to Tmack because with out the gratings this would have been impossible!

This first picture is of 2 gratings one line and one matrix.


This next picture is of the same set up, only the order of the gratings changed.


In this picture I just rotated the gratings a bit and threw in an organic non-square object (my girlfriend) to show what the projected dots would look like.


If you look at the laser projection as a whole you can see the pattern quite well. But if you imagine that you would only realistically see one cluster on something the size of a garage door the "pattern" of each cluster looks fairly random. (Except for the one photo, but a small turn of the grating fixes that)

So I thought what would happen if I added more dots... A lot more. this is what I got.


And a small adjustment gave me this.


Not sure if this answered your questions or not, but it was a lot of fun trying to force the grating to look as asymmetrical as possible.
 

Javalin

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Thanks Bubonic for posting that. I have some more for those of us who don't have an imagination.

I lit my Christmas tree this year with 2 lasers through diffraction gratings. In the first picture you can clearly see the pattern on the wall. Then I masked the laser so it would only hit the tree. In the next few pictures you can see that the patterned look is gone.





This next video is of the laser through 2 matrix diffraction gratings on an indoor tree. You can see that the twinkle effect is in fact from the movement of the laser on the leaves of the tree. (Sorry about the awesome audio track in the background, at this point I don't even notice the sirens...)



That video was taken using this: (note the pattern) From about 5ft away. The dots would obviously be spaced out much more if I were able to move back more.

 

Teslanium

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Ran across this interesting thread, I may have something to contribute toward the generation of "random" dots/sparkles. I have a jar of "Glowble Metalflake", a product intended to be added to transparent automotive finishes to give a sparkling appearance. It looks like glitter but the flake size is much smaller and the flakes are very flat squares.

Anyway, when I shine a laser into the jar and move it around, it's light sparkle heaven all over the walls and ceiling. Perhaps something like this, or just glitter, could be used for the effect desired (?). The spots produced are not as precise as those from a grating.

I took some (admittedly crappy) pics with my cell phone that show the result but am not at a computer right now that I can send them from, I will have to do that from work tomorrow.

T.
 
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