Undergrad How do I stretch a laser from a beam into a sheet?

[Gleb1964]

There are standard optical components used for generating lines from laser beams, known as Powell lenses. These lenses are manufactured with various divergence angles.

A typical laser beam has a Gaussian intensity profile. The principle behind a Powell lens is that it splits the laser beam into two parts and recombines them in such a way that the Gaussian profiles cancel each other, resulting in a uniformly distributed line. Powell lens assemblies allow the laser line to be focused at a desired distance, ensuring a sharp line with even intensity along its length.

 

[DaveE]

you need a concave lens to spread the beam

Either will spread the beam in the far field.

 

[sophiecentaur]

Either will spread the beam in the far field.

How far, though? You would want it to be compact, I assume. OP didn’t say the focal length. I didn’t understand it ‘not working at all’.

Maybe the fan out dispersed the energy too much.

 

[DaveE]

Maybe the fan out dispersed the energy too much.

That's my guess too. It's too simple not to work at all.
Scanning has an advantage in brightness over divergent optics.

PS: Google says laser levels don't scan though.

 

[sophiecentaur]

Scanning has an advantage in brightness over divergent optics.

In many ways that would be true; you can be much more 'adventurous' than you can with static optics and get an almost parallel sided output. But moving parts?? I wouldn't go there'
The context of this thread is still unknown. It strikes me that the OP got himself a laser and waved it about on a rainy night. Reasonably enough he came to the 'fan' idea but with no specific application (except for nice photos perhaps. This is just where I could be, too.

I wonder if it might be worth while playing with some shiny cutlery (spoons and fork handkes) to see hoe they affect the laser beam.

My guess would be a second hand laser level from Facebook Marketplace would do the job for a fiver.

 

[jsluka]

No smoky medium. I would like to create a plain of laser light to take video of rain water or snow falling through it as a little art project.

So all you need is the standard beam spreader used in a laser level that produces a line on a wall. So quick and dirty, try shining a laser through the round stem of a wine glass and point that at a stream of water drops :). Anything that falls between the laser and the wall will reflect the laser. In other words, there is a "sheet of laser light" created by the typical laser level. You can't normally see it since there is nothing interrupting the sheet (until it hits the wall). But if there are water drops falling through the sheet, they will light up in the beam.

If you use a couple lasers and spreaders with their planes parallel to the ground but at different heights the raindrops should look like falling blinking lights.

 

[LightningInAJar]

I went ahead and got a Powell lens on Amazon. It seems to do the trick. It's a small lens. Any special holders with maybe camera thread adapter to stand up?

 

[DaveE]

I went ahead and got a Powell lens on Amazon. It seems to do the trick. It's a small lens. Any special holders with maybe camera thread adapter to stand up?

You can just use a good epoxy to glue it to whatever you can find (hint: eBay...). You shouldn't need anything special. You probably will need some sort of tooling (masking tape?) to hold it in the position you need. If you do want to spend a bunch of money on a special mount look at Thor Labs.

 

[sbrothy]

I can vouch for Thor Labs (no affiliation). I've been directed there for many of my needs for my DIY project. Sparkfun too (again no affiliation).

 

[sophiecentaur]

I went ahead and got a Powell lens on Amazon.

Wow, that looks expensive. Going down that route could be the thin end of the wedge. I would suggest buying a 9mm drill and use it to make a hole in a piece of wood and mount it there. A sleeve of card )or something equivalent) would avoid spoiling the (nice) Powell lens with glue

 

[sbrothy]

In many ways that would be true; you can be much more 'adventurous' than you can with static optics and get an almost parallel sided output. But moving parts?? I wouldn't go there'
The context of this thread is still unknown. It strikes me that the OP got himself a laser and waved it about on a rainy night. Reasonably enough he came to the 'fan' idea but with no specific application (except for nice photos perhaps. This is just where I could be, too.

I wonder if it might be worth while playing with some shiny cutlery (spoons and fork handkes) to see hoe they affect the laser beam.

My guess would be a second hand laser level from Facebook Marketplace would do the job for a fiver.

A couple of laser goggles might be a good idea. Lots of scattering possible!

 

[LightningInAJar]

Wow, that looks expensive. Going down that route could be the thin end of the wedge. I would suggest buying a 9mm drill and use it to make a hole in a piece of wood and mount it there. A sleeve of card )or something equivalent) would avoid spoiling the (nice) Powell lens with glue

I'd rather not use glue on a $40 lens. I was thinking more a clamp of some kind? They have 3 nob tightener type clamps which can screw onto a tripod type thread?

 

[DaveE]

If you are so inclined, you can make a good clamp with simple tools in a block of whatever (I'd use Aluminum). Drill a hole just a tiny bit larger than the lens, cut a slot, and squeeze it gently with a screw. Like this:

PS: Don't make the flexure side (opposite the cut) as large as I drew it unless you're a good machinist.

 

[DaveE]

Also for an easy kludge, a hose clamp and foam tape around the lens. Not great in the optics world, but you get what you pay for. It'll work.

 

[sbrothy]

Again, I hate to repeat myself but protect your eyes. It's no fun going blind.

EDIT: Or at least so I hear. I have no personal experience.

 

[DaveE]

Your laser will have a label that describes the hazard level (class). You might or might not need eye protection. Don't stare into the beam. Position the laser close to your lens so shiny reflective things aren't likely to intervene. Once it's expanded into a line it is unlikely to be a significant hazard, depending of course on the power of your source. I'm guessing that you aren't stupid, and that you didn't want to spend enough money for a laser that was dangerous in this sort of application.

 

[sophiecentaur]

. It's no fun going blind.

Literal blindness is unlikely here but patches and streaks of damage on the retina are more possible.. Things can 'disappear' for your visual experience. OTOH, gazing at the Sun can really Rodger your sight. Didya know that ancient navigators used to go blind in one eye after a short career, using the Backstaff. The Sextant was then invented, which presents the eye with a dim reflected image of the Sun to coincide with an image of the horizon. Always best to look at the 'spot' from the laster, rather than to look down the foresight..

 

[Gleb1964]

A Powell lens typically requires fine alignment in one direction, while it is insensitive to perpendicular displacements. We typically used semiconductor lasers with integrated focusing and a removable, adjustable Powell lens head, where the lens holder moved transversely to the optical axis in a Dove-type arrangement and was then secured with a screw.

 

[sbrothy]

Also for an easy kludge, a hose clamp and foam tape around the lens. Not great in the optics world, but you get what you pay for. It'll work.

View attachment 368117

This would also make a beautiful engagement ring!

BTW, When I said I had no experience I meant with going blind! I have lots of lasers and protection googles. I still have my sight. At least as much as I had when I started.

 

[DaveE]

Y'all would be appalled at what engineers did in the cowboy days of the laser manufacturing business. They were careful (usually, LOL), they knew what they were doing, but they didn't usually wear glasses*. They complained that the glasses made it hard to see the beam(s) they were working with. Injuries were very rare. Now they wear them because the companies got big and hired safety people and such.

I never wore them unless I was told to in someone else's lab. My beams only ever travelled a few inches into a power meter. The set up (containment) is where most of the safety comes from. If you're playing with your laser like a teenage John Wayne, then wear glasses and give some to everyone else around you too.

* If they did, that was a lab I would just stay out of if possible. It meant they didn't trust their beam containment.

 

[sbrothy]

Y'all would be appalled at what engineers did in the cowboy days of the laser manufacturing business. They were careful (usually, LOL), they knew what they were doing, but they didn't usually wear glasses*. They complained that the glasses made it hard to see the beam(s) they were working with. Injuries were very rare. Now they wear them because the companies got big and hired safety people and such.

I never wore them unless I was told to in someone else's lab. My beams only ever travelled a few inches into a power meter. The set up (containment) is where most of the safety comes from. If you're playing with your laser like a teenage John Wayne, then wear glasses and give some to everyone else around you too.

* If they did, that was a lab I would just stay out of if possible. It meant they didn't trust their beam containment.

Well, if it’s confessiom time I must admit I don’t use the glasses much. I bought them too dark and the beam path is very short. The key is to keep reflective surfaces away.

 

[sbrothy]

Y'all would be appalled at what engineers did in the cowboy days of the laser manufacturing business. They were careful (usually, LOL), they knew what they were doing, but they didn't usually wear glasses*. They complained that the glasses made it hard to see the beam(s) they were working with. Injuries were very rare. Now they wear them because the companies got big and hired safety people and such.

I never wore them unless I was told to in someone else's lab. My beams only ever travelled a few inches into a power meter. The set up (containment) is where most of the safety comes from. If you're playing with your laser like a teenage John Wayne, then wear glasses and give some to everyone else around you too.

* If they did, that was a lab I would just stay out of if possible. It meant they didn't trust their beam containment.

Reminds me of the story about Feynman sitting in his car observing the first nuclear bomb test while all the others sat inside a bunker behind 10cm protective glass. If that story isn't apocryphal it's the pinnacle of nonchalance bordering on arrogance!

 

[DaveE]

Reminds me of the story about Feynman sitting in his car observing the first nuclear bomb test while all the others sat inside a bunker behind 10cm protective glass. If that story isn't apocryphal it's the pinnacle of nonchalance bordering on arrogance!

Or good risk assessment. I doubt that he was nonchalant. It took him more than 40 years to die of cancer at age 70, which also happened to a lot of people that didn't watch an A-bomb.

This, except 'analyze the nature and source of the hazard' was left out. That's done first.

I'm not saying don't use PPE. I'm saying don't always or only rely on PPE. It's an important tool, but it doesn't absolve you, or your boss, from other safety considerations.

Many of those old school laser cowboys thought that the glasses made them less safe. IDK if they were right or not, it all depends on the details, the analysis.

 

[sbrothy]

Yeah well cancer is a crapshoot. Living healthy is still a good idea but no one is really secure from it's arbitrary onslaughts. He trusted that the windshield would protect him from X-rays but I'm sure they were pretty far away too. Further than some of the troops issued with sunglasses and used as guinea pigs I'm sure.

 

[LightningInAJar]

Again, I hate to repeat myself but protect your eyes. It's no fun going blind.

EDIT: Or at least so I hear. I have no personal experience.

Only using laser point and definitely pointing away.

 

[LightningInAJar]

The lens has like 3mm diameter so the holder would need to be tiny. Ideally would like something that can be secured to a camera tripod thread. I have a 2 camera bar that can hold two cameras. I was thinking one could hold the lens, and the other a claw grip holding the laser pen.

 

[sophiecentaur]

bordering on arrogance!

Dat's mah boy. Brilliance and arrogance often go together - but where would we have been without him?

 

[sophiecentaur]

. I was thinking one could hold the lens, and the other a claw grip holding the laser pen.

I would say that the laser and lens should be fixed together and the laser should be supported by a single fixture to the tripod. If you can support the laser in a plastic tube and then use a smaller tube to hold the lens. There are various mounting brackets for camera tripods - you'd need to trawl through budget camera supplier websites. There's a load of stuff for holding standard lenses.It would be a matter of fitting the laser. I have never tried but there are a lot of low cost adaptors for fixing lenses to smart phones and clamps for fixing phones to sticks / tripods.

Do you have any hand tools? That could make a huge difference to what you do and the overall cost of this. Duct tape works well for fixing things together. It all depends on your particular DIY skills.