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How to make a laser grid?

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Hi Guys,
I think it would be really cool to make a laser grid, but I'm not sure how to start.

Attached is what I'm looking to make.. It would be cool to get a fine grid and take pictures with the laser pointed to 3d objects!

Can this be done without a scanner? Perhaps with one of those crappy caps that comes in weird shapes on 5mw res pointers? I've seen straight lines from those anyway...
 

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Murudai

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lol, you just can't 'make' a diffraction grating with tools in your shed :p They're very complex things.

It is a very precise and very complicated pattern that makes them put out the shapes they do. I studied diffraction gratings as part of the X-Ray crystallography at University I was doing. And even if you possess all the equations and values to form the shape, actually etching that pattern precisely on a scale you can't see without a strong microscope is way, way beyond a hobbyist.


And also, diffraction gratings work by deflecting all the little dots, so any 'line' you might make will actually be made of a ton of dots. Not sure if that would work in your application or not, but if you fire it far enough away the dots will become clear. You won't get a nice line like a scanner can do.

In fact, in that light I can't remember ever seeing a diffraction grating that spits out fine enough dots to call it a line. Theoretically there is one, so you just need to look :)
 

Cyparagon

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They are available in some cap sets.



It's a gamble though. You could buy one set and get two, or buy three sets and get none. They are also only available in a 4x4 pattern as far as I've seen.
 

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Benm

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It works to some degree, but its nowhere near the quality obtained with even the cheapest of x-y scanners.
 

wummi

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Murudai said:
lol, you just can't 'make' a diffraction grating with tools in your shed :p They're very complex things.

It is a very precise and very complicated pattern that makes them put out the shapes they do. I studied diffraction gratings as part of the X-Ray crystallography at University I was doing. And even if you possess all the equations and values to form the shape, actually etching that pattern precisely on a scale you can't see without a strong microscope is way, way beyond a hobbyist.


And also, diffraction gratings work by deflecting all the little dots, so any 'line' you might make will actually be made of a ton of dots. Not sure if that would work in your application or not, but if you fire it far enough away the dots will become clear. You won't get a nice line like a scanner can do.

In fact, in that light I can't remember ever seeing a diffraction grating that spits out fine enough dots to call it a line. Theoretically there is one, so you just need to look :)
at the moment i am experimenting with the tools i posted before. my attempt is to make the interference pattern as small as possible with household items. as the guy in the link i posted got kind of a result at 300 dpi (!) a fine photographic film may get to about 4000-5000 dpi.

i printed out some test pattens and photographed them with a high quality analog camera (Canon t90). if my calculations of the corresponding sizes are correct, i should get a pretty good grating. pictures and information soon on this forum, when the film is developed.

as you already have worked on gratings. what dou you think is my chance of success? :D
 

Murudai

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Well, I did study a bit of this stuff but not enough to be an expert :)

That's an interesting idea though. I'm not sure how much fidelity you'd get by taking a picture of something designed to distort light, lol, but in theory I guess you could do it.

I was more talking about making custom diffraction gratings from scratch, just copying an existing grating would skip most of the difficult steps.

So yeah, if you can get a clear enough picture that's fine enough in theory it could work, so I'd be interested in seeing what you come up with :)
 

Benm

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Making patters so small by photographic means will probably prove very problematic. You are trying to make something with details so fine they are in the order of the wavelength of the light you are using for exposure.

It would probably be doable with UV equipment as used in microchip lithography, but getting down to the proposed 5000 dpi is difficult with visible light - those are 2 uM details you're trying to make with 0.4 to 0.8 uM light!
 

wummi

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@Murudai

the pattern is generated with a free tool (see above) and printed full size to an A4 sheet. this is then photographed, so theoretically, the grating should be about the right size on the film. i just hope the exposures are about right :)

Benm said:
Making patters so small by photographic means will probably prove very problematic. You are trying to make something with details so fine they are in the order of the wavelength of the light you are using for exposure.

It would probably be doable with UV equipment as used in microchip lithography, but getting down to the proposed 5000 dpi is difficult with visible light - those are 2 uM details you're trying to make with 0.4 to 0.8 uM light!
wouldn't 5000 dpi be about 5µm details? 0.0254m / 5000 = 5.08 µm


anyways, i also exposured some shots with green dpss laser light. i have no idea if thats good or bad, we will see when the film is done.
 

Benm

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Well, if you want dots 5 uM apart, there needs to be white between those dots, making the actual detail required at least half of 5 uM.

Exposing with the wavelength you are going to use them on is probably the correct way to go - as is used in holography.
 

Toysrfun

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Hi Guys,
I think it would be really cool to make a laser grid, but I'm not sure how to start.

Attached is what I'm looking to make.. It would be cool to get a fine grid and take pictures with the laser pointed to 3d objects!

Can this be done without a scanner? Perhaps with one of those crappy caps that comes in weird shapes on 5mw res pointers? I've seen straight lines from those anyway...
I know thisnpost is a little older but I have been doing some research myself and not sure what your purpose is however for my project I’ve decided to use 4 cross lasers and overlap them. That doesn’t produce an outside edge but it will make a grid done right. Mine for purposes of industrial scanning will use two blue, a red, and a green with 60 degree crosses so they can overlap closely and different refraction between the colors to compensate for variances in item material I may be scanning. I’ve not had any luck other than expensive ones ($600) for full quality grids.
 

hakzaw1

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PAUL-- 'You joined today and the first thing you did was necropost to a nine and a half year old thread?! Not good. Not good at all. '''

ALWAYS CHECK THE DATES
You should have just started a new thread in Optics.
__________________________
Hi Guys,
I think it would be really cool to make a laser grid, but I'm not sure how to start.

Attached is what I'm looking to make.. It would be cool to get a fine grid and take pictures with the laser pointed to 3d objects!

Can this be done without a scanner? Perhaps with one of those crappy caps that comes in weird shapes on 5mw res pointers? I've seen straight lines from those anyway...
5.50
Grid lens kit for 12x30mm AixiZ modules
[AIX-LENS-CIR]__________________

well.. follow the link
http://www.aixiz.com/store/product_...d/148/osCsid/8537131306a67bdc956027eb1a1d97f4

grid GRID.jpg

its a 5X5 grid---simple 'lens' one laser no prob. fits standard AixiZ/ Merideth modules
12mm
tell AixiZ Len from LPF sent you..( I owe them money..so)
 




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