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RGB Diffraction Grating

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Chris44448888

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Question here - is it possible to have a set of double axis diffraction gratings set so that an RGB laser beam could produce a white light matrix pattern. I know the diffraction gratings would need to be set before the beams are combined. I assume the lines/inch would need to be adjusted for the wavelengths. Would this work?
 





sightfx

sightfx

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Wow, That is a good puzzle for our optics geniuses if I ever heard one.

:pop:
 
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nikokapo

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So you'd have to somehow combine the multiple beams coming out of the first grating with a second grating... But if the second optical object is a diffraction grating then it would diffract them again.

It could be done if you managed to get each separated beam and then combine the RGB for each beam. Not easy, not economically viable either, you'd be better off using a laser projector emulating a laser grid with dots.
 
Flaminpyro

Flaminpyro

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:pop: Yes I want to know the answer to this one ! is there any more optics geniuses out there
12V12W
 
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C

Chris44448888

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I'm pretty sure it just a matter of getting the grating angles correct, but two to calculate them? The beam size and shape would need to be the same also.
 
Cyparagon

Cyparagon

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Would be far easier to just use a scanner, but assuming you could find a wide enough variety of lines/inch to correct for the differing angles for each wavelength (Probably not possible, but if you could) it should work with 3 diffraction gratings in addition to the two dichros, but one of the dichros may need to be rather large. Here's what I came up with:

attachment.php
 

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Chris44448888

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Thanks Cyparagon, that's the way I envisioned it. You could focus the diffraction pattern so it was small before it went though the dichros. But how do you figure what the specifications for the grating??
 
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nikosb

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Cyparagon said:
Would be far easier to just use a scanner, but assuming you could find a wide enough variety of lines/inch to correct for the differing angles for each wavelength (Probably not possible, but if you could) it should work with 3 diffraction gratings in addition to the two dichros, but one of the dichros may need to be rather large. Here's what I came up with:

attachment.php
Click to expand...

In the above example it assumes that the DGs are different for each wavelength to produce the same diffraction angle. What about using exactly the same DG for each wavelength but add a convex or concave lens past the DG that would focus or expand the beam respectively to match the diffraction angle.

Let's take for example the red and green combination only. Let's say green beam would diffract with an angle of 10 degrees. Red beam would diffract with a higher angle, let's say 15 degrees. Using a concave lens after the DG of the green beam would increase the diffraction from 10 degrees to 15 degrees, matching the diffraction angle of the red beam. Or vice versa, use a convex lens after the DG of the red beam to reduce the diffraction angle from 15 to 10 degrees. Would that work?
 
H2Oxide

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Wow, that's a necropost if I've ever seen one. But still interesting and relevant. :D
 
Alaskan

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Holy cow, I struck gold and found what I was looking for with a search, amazing... Now to find the diffraction gratings I can use for this, if anyone can give some pointers, much appreciated.

I found this on google, I don't have to make white, this kind of beam profile is of interest to me too, maybe I can find something fairly inexpensive on ebay to try this out with, recommendations?

1407LFW01f2B_zps025wv5r7.jpg


http://www.laserfocusworld.com/arti...g-high-energy-lasers-for-the-battlefield.html
 
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Cyparagon

Cyparagon

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nikosb said:
What about using exactly the same DG for each wavelength but add a convex or concave lens past the DG that would focus or expand the beam respectively to match the diffraction angle.
Click to expand...

Nope. The lasers' dots would change size as well.
 
Alaskan

Alaskan

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LazeristasUVISIR

Now I can see, the artwork represents the three beams as red, green, blue, but the actual beams are 1, 2 and 3 lambda, exact multiples of wavelength making the grating work well. Thank you for pointing out RGB are really so close together, I've known it by the numbers, but never realized how close they really are in terms of nm until you wrote that.

Unless there is a already built made for this application R,G,B grating, I'm out of luck, won't be able to pay for something special, I think. I've been googling and have found some articles on diffraction gratings, it appears they are not very efficient, could loose half of the power using one, it appears. Do you know of any high efficiency gratings which can do more than 80%?

Thanks
 
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