Q to laser users (maybe lab based rather than industry)

[ReverendCounter]

Does anyone work with lasers in a way that could possibly give any insight about creating a diffracted beam from a single source which results resulting in multiple beams with diameters in the micron range?

ie, could you use diamond fragments/dust to create a head which would diffract a single beam into multiple rays, or is there another method of creating these multiple beams in with this sort of diameter?

[kingb]

How much power? Spacial light modulator maybe?

Edited by kingb on Friday 17th November 09:45

[Monty Python]

How many beams and what tolerance do you need on the resulting beams, and do the beams need to be on constantly?

[EliseNick]

In principle you can take the 2D Fourier transform of the required pattern, and use a diffraction grating with that spatial amplitude/phase modulation. But whether this is practicable depends on the required pattern. If you want a square grid of spots, a square periodic lattice will do the trick. If the spot pattern is aperiodic, and you don't require too many of them you might find it better to use a network of beam splitters. More details needed really.

[ReverendCounter]

Thanks for the interest and info.

I understand it's all very vague on my part but unfortunately it probably wouldn't take much to ID something that needs to stay under wraps for the time being, so rather boringly some beans will have to remain unspilled.

How much power?
Enough to make a clear mark in a range of different materials - but - not so much to create micro holes through thin metal sheet, for instance

How many beams and what tolerance?
Lots (sorry, as many as possible) and say, from 15 to 25 microns in diameter

Do the beams need to be on constantly?
Yes, preferably but it could pulse to cool if required, or the main beam could flip flop between two identical heads where they'd fire alternately if that helps?!

With regard to patterns and Fourier Transforms and beam splitters and lattice mods etc etc etc - the pattern can be random.

Sorry that I can't just state what the intended application is, I know this is all vague - but these are first Q's on something I've been thinking about for a few years now.

ps could the device which creates multiple, micron dia beams be mounted onto a commercial laser?

[V8LM]

Assuming it's not the beam you require but focused spots on a surface then a spatial light modulator would probably be the best way to go (but takes up space). As said above, the SLM is placed to reflect the laser beam onto the back aperture of a focusing lens (objective). The SLM projects the Fourier transform of the pattern you want to create. This is how holographic optical tweezers work.

[ReverendCounter]

V8LM said:

Assuming it's not the beam you require but focused spots on a surface

Yes, it's definitely the end result I'm interested in, rather than the activity or properties of the beam. I've also looked at wire/spark erosion to achieve the same results, but due to the requirements of that process it's not really appropriate.

V8LM said:

a spatial light modulator would probably be the best way to go

Thanks for the suggestion (if you don't mind, there doesn't seem to be a Dummy's Guide to SLMs and I have some really fundamental questions!)

What sort of area could they address and at what speed? ie, could the pattern be repeated if there are limitations to the area? Would they be OK to use as part of a repeated production process - ie, any duty cycle concerns?

[V8LM]

SLMs are driven as a display (HDMI, DVI, etc) and have similar frame rates (60 Hz).

https://holoeye.com/wp-content/uploads/Spatial_Lig...

I don't know how much power your application needs. This might be the limitation.

https://link.springer.com/article/10.1007/s00339-0...

Edited by V8LM on Sunday 19th November 10:48

[Monty Python]

What power is your source? One problem you may find is that the more beams you produce, the less power each one will have and you may not be able to mark the surfaces you're interested in.

[ReverendCounter]

V8LM said:

Read these and educate yourself

Thanks for the links (ignore the cheeky misquote!) - been trying to evaluate the application of the SLM process since you posted them. Interesting and brain flexing.

[ReverendCounter]

Monty Python said:

What power is your source?

Haven't actually ID'd the end material - was bit of a catch 22 amnd wasn't sure where to start - do I figure out the process or do I ID the material to be processed and see which processes will give best results. However now V8LM has offered up a solution, the material and it's resilience to the beams can be ID'd next.

[V8LM]

ReverendCounter said:

Monty Python said:

What power is your source?

Haven't actually ID'd the end material - was bit of a catch 22 amnd wasn't sure where to start - do I figure out the process or do I ID the material to be processed and see which processes will give best results. However now V8LM has offered up a solution, the material and it's resilience to the beams can be ID'd next.

Depending on what material you wish to 'manipulate' and what the end result you desire you could also think about coating the material with a photoresist, use the laser to remove the resit, and then chemically etch, then remove the resit. (similar to silicon chip manufacture).

See https://en.wikipedia.org/wiki/Photoengraving

[ReverendCounter]

V8LM said:

Depending on what material you wish to 'manipulate' and what the end result you desire you could also think about coating the material with a photoresist, use the laser to remove the resit, and then chemically etch, then remove the resit. (similar to silicon chip manufacture).

See https://en.wikipedia.org/wiki/Photoengraving

That's a really interesting suggestion - for a second it provoked the thought about going a step further with something like inkjetted acid, but the particle size wouldn't be small enough.

I'll look into that. Thanks.

[ReverendCounter]

kingb said:

How much power? Spacial light modulator maybe?

BTW, thanks for raising this kingy, sorry I didn't pick up on your suggestion

[ATG]

ReverendCounter said:

Does anyone work with lasers in a way that could possibly give any insight about creating a diffracted beam from a single source which results resulting in multiple beams with diameters in the micron range?

ie, could you use diamond fragments/dust to create a head which would diffract a single beam into multiple rays, or is there another method of creating these multiple beams in with this sort of diameter?

Perhaps you could clarify the requirement a bit without giving the whole game away. Do you really need beams in the micron range or do you just need to project micron sized spots of light onto something ... i.e. larger diameter beams focused to micron size spots. Can the beams approach your target from the same direction or do you need to be able to approach your target from multiple angles. And do you strictly need to use an initial single beam (e.g. is coherence of the multiple beams important?) or could you use several laser sources?

[ATG]

Oh, and what sort of thing are you thinking about when you say "commercial laser"? Depending on your line, that could be anything from a diode in a consumer disc reader to something for cutting sheet steel.

Edited by ATG on Monday 20th November 17:14

[ReverendCounter]

ATG said:

1) Do you really need beams in the micron range?
2) Can the beams approach your target from the same direction?
3) And do you strictly need to use an initial single beam (e.g. is coherence of the multiple beams important?) or could you use several laser sources?

1) I need to create many micron sized impressions over an area (after looking at SLM, probably larger than the area offered by that process)
2) I'm fairly sure the end result wouldn't be affected by direction
3) No - had assumed it would be cheaper to use an existing common laser used in cutting industries which wold probably just have the single output/beam

In hindsight, perhaps some kind of photo etching might be more practical given SLM machines.

Edited by ReverendCounter on Monday 20th November 17:20

[ReverendCounter]

ATG said:

Oh, and what sort of thing are you thinking about when you say "commercial laser"? Depending on your line, that could be anything from a diode in a consumer disc reader to something for cutting sheet steel.

My thoughts were to retrofit an existing laser cutter with decent spec with some kind of device - but yes, something with a flat bed rather than a small consumer item.

[Monty Python]

Sounds like you're after a laser micro patterning machine.

https://www.oxfordlasers.com/laser-micromachining/...

[ReverendCounter]

Thanks MP, that looks like a really appropriate process (or possibly one that could be adapted).

Really interesting outfit, thanks for the link.