Coupling Laser beams into Fiber Optic Cable!
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- čas přidán 5. 07. 2024
- Episode 46
#fiberoptics
#fibercoupling
#laser
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In this video I demonstrate how to couple Lasers into Fiber Optic cable quickly and easily using a fiber visual fault locator, some mirrors and some DIY fiber collimators.
I also couple light into Multimode and Singlemode fiber, and demonstrate what happens when you exceed a fiber's bend-radius.
Fiber optics is far more interesting than just telecoms, there a variety of unusual applications including high voltage sensing , temperature measurement and more!
I have a couple of way interesting projects in the pipeline exploring cool stff with fiber optics, so subscribe!
0:00 Intro
0:08 Fiber optic cables
2:06 Fiber Colimator
3:14 Coupling Light DIY Fiber couplers and Collimators
5:54 Visual Fault Locator
7:51 Coupling a Laser into a Fiber Optic
11:55 Coupling into single mode cable
13:00 Fiber Bend Radius
13:46 Outro and credits - Věda a technologie
5:30 you can use focusing lense module from DVD drives which can give very focused beam but with extra electronically focusing features so With that fine tune would be much easier and you can note and tell by looking at input power of the coil to find exact focus Point .
Thanks for the collimator hacks! "Perfect" really is the enemy of "good enough" sometimes.
TBH, the alixpress collimators are really only "good enough" as well. A "real" collimator from the likes of Edmund or Thorlabs would easily set you back over a hundred bucks each, but I dont have the luxury of an infinite budget. If good enough works, then it works for me :-)
my understanding is that free space to fiber launch, especially in devices based on small numbers of relatively high power off the shelf emitters, use so called "coreless fiber end caps" to facilitate setup and mitigate practical problems.
they can be >10x larger in diameter (800 micron outer cladding high power multimode fiber with 9 mm end cap), with much greater mass to sink thermal effecss, dampen resonance and alignment issues (from microscopic movement or resonance driven by ambient noise or thermally)
Very interesting, Les!
Back in 1980, I attempted pushing a 5 watt argon beam down a 100 micron, single core quartz fiber, with a parabolic refractive index, which guided the beam towards the center. Didn't have any fancy lens assemblies, so I made mine with a piano-convex lens glued to the bottom of a glass tube, mounted vertically.
The fiber end was held by a mechanical pencil's collet, which allowed for easy focusing.
In order to eliminate surface reflections, I filled the glass tube with glycerol, which has ~ the same refractive index as the lens and fiber.
The objective was to deliver a scanable beam to a pair of remote galvos, inside a scanning head, located in the lighting truss, in order to avoid heaving ion lasers on top of 10 towers.
Worked fine.. until, as you explained, the beam missed the end of the fiber, heated the cladding, which expanded, making the alignment even worse. Furthermore, I was unable to achieve the appearance of a parallel beam for over 20 ft from 5 mm scanner mirrors.
Laser Diodes have literally been game changers for laser entertainment. No 30 amp 3 phase, water cooling, hoses, pumps, frozen tubes during transport in winter. Higher wattage @ 10% the cost and hassle.
Nice! I like the idea of holding a fiber in a mechanical pencil collet, genius! I will give that a try!
Collimating fibers, especially over long distances is hard for sure. I have spent quite a bit of time over the last month trying to get to a satisfactory collimation solution, and it is good, but will never be as good as the beam from a gas Laser!
For sure, Laser diodes changed everything. they kind of take the fun out of building Lasers in a way, so I suppose the thing to do is find novel and cool things to do with them!
@@LesLaboratory Thanks Les.
lol! So, you were more impressed with the pencil collet than using glycerol to create an invisible transmission junction for light?
'Beauty is in the eye of the beholder', indeed. No offense taken.
I found that the focal point of a fiber isn't only at the end, but extends into the fiber, itself. That's where the problem lies and why I attempted to use a self focusing fiber of the smallest diameter and parabolic refractive index.
Yes, an exposed SP165 tube is a wonderful thing to behold. TEM 00 beams are the essence of optical perfection. Building optical systems with them permanently installed within a clean lab are great fun.
Bu, touring with them, while uninsured, with back to back gigs for months during freezing winters is a very different matter. Gotta blow all the water out of the cooling system, before the get-out, or they'll freeze in transit.
RGB modules inside a compact, 110 VAC, case, with a fast pair of galvos is all we laserists need on the road..
BR😎
What he said
@@TheOleHermit It's the little things! Of course the glycerol trick was good, but holding bare fibers has been on my mind lately ;-)
@@LesLaboratory Technically speaking, I was holding the fiber by the cladding.
I suggest using a pinhole mask to avoid hitting the collet with the focused beam, in order to keep from heating up one side of the collet and fiber, in case of probable misalignment.
If only heated from one side, the fiber will expand, bend and become self destructive.
BR
Superb video. Thanks for sharing this information.
You are welcome!
Great stuff, looking forward to the optical fibre sensing that comes next!
Thanks! There is so much that can be done with this stuff,..
I liked the py spectrometer, so thank you for helping to guide us with a useful, affordable thermal imager. Just bought one from Amazon based on how well it works for you. PS, at least here in the USA its on sale.
Awesome! Yea, I think they do rolling price drops one country at a time. Last week they were 235 bucks!
We used to measure all sorts of stuff with fibers. I was working with Ion Implanters and fibers were used to cross the High Voltage barrier...cheers.
Nice! I would love to get into playing with High Vacuum again. The stuff is still sitting under the bench, waiting patiently...
Great video! Thanks for providing a simple way of doing something that can be frustrating and seem like shooting in the dark sometimes. I have a question though. Is there a preference between PC or APC couplers for better coupling performance?
Great job sir thanks
Thanks Les, this was interesting again. I have used ball lenses for focusing light into/out fibres. They are mchanically a bit easier to handle and align
You are welcome. Yeah, I keep meaning to try those.
The first time I collimated a single mode fiber coupled laser I was astonished at how good the beam get. This was with some of the 976nm 14 pin lasers. I want to fiber coupled a few visible diodes and see what the results are. I want to try putting the fiber right up against the die of the laser itself. Glad you posted this video, great work!
Me too! Out of 9 micron fiber you can get a super tight beam. Out of multimode not so much, that said is the phsics is just right, you can get needle sharp beams out of those too :-) You are welcome!
It is possible to couple a fiber right to the output facet of a diode, but many diodes have oval divergence patterns on the uncoupled facets. Two 90° cylinder lenses can be used to collimate the two axes, or to inject them into fiber.
great video!!!
Thanks!
love it
Good Stuff
Excellent video! Not much of this kind of info on youtube. I'm currently researching how to optimally couple light from a 3mm diameter diffuse, incoherent source (back-illuminated skin) into a 500um fibre for a medical application (similar to pulse oximetry). Trying to get my head around the conservation of etendue concept to understand whether I can do better than just butting the fibre straight to the skin. Do you know whether collimation optics can help in this situation? Keep building!!
Pointing those beams almost into the viewer's eyes honestly feels a bit scary.😉
I could not resist! :-D
Are there thick OF like of 5 mm 10 mm ! ??or can we built it like using hot glue and rubber pipe or any similar materials with different R I ?
That can be use to take Sun light to the room by focusing the sunligh beam and using sun tracking system .
I'm after some advice for a very specific problem. I need a laser powerful enough to burn carbon/soot but has a flexible fibre to get into hard places. The carbon/soot is located inside drilled holes within a car engine pistons.
They are called the oil return holes and take oil from the oil control ring through the piston back into the crankcase, all car pistons have these holes, but some cars they get clogged up with carbon deposits.
The idea is to remove the bottom oil pan and burn out this soot/carbon deposit with a laser, the holes are usually quite small maybe only 1/8 of an inch in diameter, but can be quite long all the way through the piston ( 1/2" or more at thickest part of the piston head).
To clean out these holes requires engine rebuild, if its possible to clean them out with laser would be very advantageous.
Hello, nice video, can I do this with a 445 nm 10w laser for cnc? Thanks
£0.31 a metre in bulk, I never thought that kind of cable was so cheap.
it's crazy! I have over a quarter mile of this stuff now on a small budget. At a certain length, shipping exceeds the cost of the cable!
@@LesLaboratory yep, quite amazing
@@LesLaboratory perhaps you could post links to the equipment you use and generate a bit of income?
Amazing video, really informative. But have a question, How much power does it require to run 4 x 650NM±10NM lights?
Awesome video, I'm tripping baaaalllzzz mayne. Jerry Garcia is GOD
Very helpful video! It's a fascinating field. Thorlabs has a lot of informative videos, but I like the DIY flavor. I've wondered how feasible it is to DIY a fiber optic -thermocouple- _probe_ for use in a microwave oven. Probably out of the question because of the special composition of the glass.
Thanks! Yeah, I have watched Thorlabs' stuff, but I wanted to do a 'can you hack it' style video (plus, I don't want to waste time in the next video, explaining how coupling works!)
Interesting, I am not sure on this one, from the papers I have read on the subject, the fibers (or at least the tips) are speciality, and might not play well with microwaves.
I have questions: How high a temperature?
Any reason a shielded regular thermocouple can't be used?
@@LesLaboratory I suppose under some circumstances you could use a conventional thermocouple? I have a microwave kiln I'd like to measure, and another use would be microwave chemistry. Just fishing a probe up through a hole in the bottom would probably be safe. Cool, looking forward to what's to come!
There was some ideas for mounting fibers for use with collimating lenses etc in the comments. For me I have had great success using a piece of aluminium about 30mm x 50mm x 2mm. I remove the buffer leaving the bare fibre exposed, make a clean cleave and then epoxy the fiber to the aluminium plate. Now it`s tempting to have the bar fiber hang over the edge a little, but this way its vulnerable to mechanical damage, so instead I cut or punch a small section of the edge away, maybe 5mm wide x 6mm deep. The fiber is mounted within this cutout so the end of the fiber is recessed from the edge of the strip but is still protruding over the edge of the recess. The assembly can then be bolted to supports on an optical bench or sled.
Great work. You said we can measure voltage with fiber optic, really? Cool!!? Have you already made a video about this? Thanks!!
there seems to be some interesting work with using polarized beam splitters to combine diode laser beams for increased power. Have you considered doing something along those lines and add in the use of a fiber cable as a part of a cutting head? ie blue laser diodes?
I have a fiber fanout that I am planning to use in reverse at some point. Basically several fibers coupled into one. I have no idea how it will work out, but it is on the list of projects!
Genesis of lab-hacks playlist.
I probably should...
Great video! Could I please know where you bought the adjustable mirror mounts from?
I picked these up from eBay, occasionally they show up cheap, especially if they are in poor condition.
Interesting
I want to couple a more powerful 75+ watt laser into a fiber optic cable. Are there any concerns I should have with that? (Laser melting cable, etc)
Looks like this is first step to fiber laser used in metal cutters. How to couple few laser diodes into one fiber?
For this is is possible to join several fibres into one if you have the right gear. I will have to keep my eye out for a fusion splicer ;-)
Love that 488nm blue... is it a blue diode or IR going through a doped crystal?
Just a blue diode.
@LesLaboratory >>> Great video. Subbed...👍
Watched a few of your videos this evening and wonder if you might have the chops to make a wideband Rydberg atom antenna/receiver... food for thought anyway.
Interesting, just glanced at the paper there. Interesting for sure, but the kit they describe is way out of my budget at the moment, but who know what the future will bring.
@@LesLaboratory Well if you can manage to excite some atoms with one laser, and probe it with another, you can make a fantastic wideband radio receiver (Army Research Lab announced in 2018), and you're also on your way to a quantum computer. Sometime tells me you might be able to pull off a few qubits after a few years thinking about it.
any comment on how to do this in a more direct diode to fiber assembly? I'd like to couple a fiber to a multi-watt diode assembly.
This is not something I have tried, but I believe it is possible, though undoubtedly tricky to directly couple a fiber to a laser diode. See this article: www.fiberoptics4sale.com/blogs/archive-posts/95046790-laser-diode-to-fiber-coupling
Can we combine with optical fibers the power of 2 or 3 laser diodes into a single more powerful beam?
Maybe an amateur question but: why the beam between the 45º mirrors looks much more intense and visible than the parallel input and output beams? Is it the camera position?
Love you videos and style, BTW!
Light is preferentially scattered forwards, rather than sideways, so a beam pointing towards the camera will appear brighter, than those parallel to it. Thanks!
Good video, thanks!
In my experiment I have to measure the wavelength of a laser, so in the lab we illuminate one end of a single mode PC fiber and then connect the other to a wavelength meter. To gather more light we focus just a little with a lens. Not strictly focus because we can burn the surface. The problem is that I find that after many laser shots the fiber starts to deteriorate, that is with some punctures in the surface, so definitely I am not focusing 100% onto the fiber core. It then starts to gather less and less light and finally our wavelength meter doesn´t receive any measurable signal.
Do you recommend the colimator solution :D?
I will definitely try to match our laser with your method because so far I just move mechanical parts of the mirrors to get a significant light signal at the end of the fiber connected to the wavelenght meter xD.
Cheers!
The fact that you managed to drive a beam into a 9 micron cable is an amazing achievement.
5:00 do you have a link for the lense? i don't finde the one that outputs a beam of the optical fiber that is in this price area.
At 5:00 the lens assembly shown is home made from an sma connector and a laser diode collimator lens, this was for an odd SMA905 fiber I had. The more common FC connector lenses are available from aliexpress at reasonable prices: m.aliexpress.com/item/1005003438926038.html
How is the coherence after it travels through the fiber. Does is still interfere with it self in an interferometer?
It's not something I had considered, however there seem to be plenty of academic papers that suggest you can build interferometer where one or both arms use fiber. :-)
I managed to make a simple liquid contact sensor for Arduino using a 1mm bent plastic fiber optic, it was quit accurate and fast, simple to make and very cheap.
Sounds interesting! Do you have link you can share?
@@davidsteele9103 comment gets deleted, can't post links, just let me know what info you need
@@mmghv If it's a URL you are trying to post, put the word 'dot' in place of any periods or '.' in the link.
@@LesLaboratory It still got delete! youtube just sucks, it's a tinyurl with the id yujt9f8a after the slash if you can construct it.
@@mmghv that works! Very cool, elegant in its simplicity! I tried sharing my stuff on that group once, but for some odd reason FB was banning my posts too!
can these fibres be used with cutting lasers?
can a splitter be used to couple multiple lasers in a powerful laser?
Suppose you coupled all beam than what percentage of light losses happened in the Cable per " legnth in meters " ??
The cable manufacture calls out those losses. It is wave length dependent.
Do you have a link for that cheap telecommunication fiber cables.? but perhaps not ideal for my usecases.
am going thrue different fibers, looking for crude cheap alternatives for spectrometer extension cable.
been trying anything from the old Toslink cables to the modern fiber cables for internet simply because of the low prices..
just been getting the cheap ones, like SC OM2 angled APC and UPC, and FC interfaces..I recall its multimode.
but they all got their weaknesses
Im seeing a big dip from around 700 to 760NM on Toslink when checking an old glowing light bulb so clearly not linear acroos the visual NM-span to near infrared.. its the visual span Im pursuing linear transfer in.. 370 to around 800nm
and these cheap fiber cables, they are very poor in transporting visual light as its not accelerated and quite dim, as the optical line seems very narrow. (at least on the cheap one, Ipicked up from CN)
Are there any cheap cable alternatives for spectrometers light travel. that is linear acroos the visual wavelength span?
sofar the Toslink cables, works way better then the optic fiber cables, I tried, and they dont seem to fluke my readings, and I dont have many coherent laser sources in the 700 to 760nm span.
But it could very likely be that Im simply not pursuing the right version of cheap optic fiber cables that got wide optical inner transmitter light path.?
what would be needed to remove mirror mounts and purely use a fibre cable to direct a beam from a c02 laser cutter
can we channel co2 laser via fiber optic cable?
that would be great
You need Polycrystalline IR (PIR) Fibers for that. I think if memory serves, you can deliver up-to 50W or so using these, but check the spec: artphotonics.com/product/polycrystalline-ir-fiber-cables/
Nice. What kind of experments do you have for us in the future?
Can you say what power that red $2 "ebay special" pointer is? Obviously they're all marketed as "5mW" to evade the brilliant and totally effective government bans, but I have a green doubled Nd one and the violet InGaN diode one of the exact same style, and they both produce over 70 mW of light with fresh batteries as measured with a good power meter at my lab. Wondering if this one is similarly insane or actually 5mW like all the old ones that first appeared in the 90s. Also, is it 630 or 670nm do you know? thanks!
That would ruin the surprise, but I am hoping to have one released before the Holidays!
Never thought to measure the power, the wavelength is known at 660nm as I have used it in the Pi Spectrometer videos. I have just measured it on the Coherent Lasercheck and it measures 22.5mW, pretty insane right enough! I remember back in the day when the first 650nm Laser pointers came out, and I had to buy one (at great expense!)
@@LesLaboratory oh god, don't remind me. I spent WELL over $100 of my diligently saved allowance as a kid in the early 90s on one from I believe Edmunds. 😳 It's embarrassing. One of the reasons I'm *trying* to hold off blowing about $300 on one of the new bright 255nm deep UV LED flashlights for my fluorescent mineral collection because the price just HAS to come down on them.
Thanks for the power measurement!
Ever mess with the kineFLEX mounts/fibers? Got a pile of argon lasers that use them, looks like an interesting solution.
I have a couple of kineFLEX mounts that came as part of a Laser assembly off of eBay, alas, it came with no cables, but yes, the mount is interesting! I reckon with some work it may be possible to build something similar but smaller that could couple onto the end of 12mm Laser diode modules. That would be pretty cool!
@@LesLaboratory I have a few spare fiber cables, but no alignment tool. Seems there are some 3D printable ones out there however. Got a half dozen argon lasers from a print shop, so, a bonanza of parts. Looks like they came out of Agfa plate-setter/printers.
@@o.e.r.3287 Hah, I sold Agfa imagesetters from my VAR (value-added reseller) business back in the day (early 1990s 😮). I’d never thought to wonder what sorts of lasers they used; I’d just assumed HeNe, possibly frequency-doubled. Maybe platesetters used argon lasers because they needed more power to expose the resist on printing plates cs photo film? I expect you could buy them for parts for a song these days, if anyone still has any collecting dust somewhere. It’d be cool to have an argon laser!
@@DEtchells These date up to late 2021 on their refurb stickers, so the tail end . Manufactured from 2007-2011 on the dates I could find. Could be a plate setter, but these are just the optics boxes/controllers, lasers and PSUs. Still trying to get them past idle mode, and finding a proper remote/controller for them is a big pain.
@@o.e.r.3287 Oh wow, those are definitely late-issue. They’re almost certainly platesetters. - I don’t know what Agfa was into in recent times, but it’s for sure they wouldn’t be film-based in that time frame. Direct to plate was just starting to come out of the lab as I was exiting the industry, but my impression is that it took over pretty quickly. The ultimate move was to image the plates directly on the press. (Maybe they didn’t even use conventional plates at that point?) The whole push was to get to direct-to-press for the sake of both efficiency, but also quality (registration could be that much better if you imaged the plates right in place).
Good luck figuring them out!
where do you buy cheap equipment online for projects like this
Mostly eBay and Aliexpress. What specifically are you looking for?
How much power could you push through a fiber like that?
I can't answer that, but this is what it looks like when you exceed that power rating- czcams.com/video/0yq0GoH0TH8/video.html
@@WaffleStaffel I was wondering if it would heat up and break/diffuse.....
Wait... It wouldn't be able to start the lit portion at the beginning and travel to the end. It would need to start at the end and move up. I have a feeling that how he's starting melt is by damaging the end and it works its way up to the laser source. But until it's damaged, it seems kinda OK.
Depends on the Fiber, and a bunch of other parameters (wavelength, pulse width, diameter of the core and so on) @WaffelStaffel, awesome video of Fiber Fuse! Nice!
@@LesLaboratory It blew my mind the first time I saw one, because there was no info on what was happening, and I had no idea what was going on!
@@xenoxaos1 He's either using a mirror, or shooting another laser into the end to get it started. Evidently damage or bending could trigger it too. Like Les said, many variables!
I hope you're wearing eyepro - tens of mW is enough to fry your eye faster than you can blink.
Of course! I mention these and where to buy them in some of my other videos.
The essential optical engineering theory is to create a relay lens which images the laser exit pupil onto the fiber entrance pupil (polished end), which image is less than or equal to the entrance pupil diameter, and with NA greater than or equal to (i.e., ray angles less than or equal to) the NA (i.e., acceptance angle) of the fiber. These constraints dictate the relay lens system. Collimation per se is not a factor.
NA?
Yes for sure. In this video I just wanted to go at it from a practical 'can we hack it' perspective. I may well do a short series on fundamentals if there is interest.
@@davidsteele9103 Numerical Aperture. See: www.newport.com/n/fiber-optic-coupling for a good explanation.
Given that comm fibers are optimized for near-IR wavelengths, would they be less sensitive to bending at those wavelengths vs the ~~~~400-550 nm wavelengths you were using? (Or is the wavelength optimization more a matter of cutting 10ths of a dB of loss over long distances, whereas the bending screws things up so badly that the wavelength doesn’t really matter?)
I'M 1444A.E.IPA481 Mr ROCKFELLER
considering the challenges, sometimes i think its best to just mount teh damn thing to the head where it always was!
um... for years years i always wanted to know "how much power can i shove down a fiber?"
i never got answers, just gibberish about bandwidths and datarates. no, POWER!
i now understand its a thing called insertion loss along with variou other factors. not that it helps much...
i always wanted to shove the laser diode (or several) on a separate mount and feed the beam witha fibre to the head... oh well.
probably best just doing it with open mirrors like a normal cutter actually.
The crazy thing is that my brother, I and my cousin got separately the idea of smartphone repair. I kind of knew a faintest but that my brother did this before but in my mind I marked it as electronic stuff. If I were rich, I would out of boredom behave as if I was kinda poor and try to make a buck incl. a limited budget. Like here, start with repair, then where to find deals and the distribution theory where and how to sell. This by not being a betrayer but e.g. find the customers that long the most like merchandise lovers.. speaking of, this was before my realisation of the relative abundance of deep state lovers.. anyway, You have tech in Your hands with that phone and You can maybe push Your learning to the up to date microchips, programming and e.g. chemistry like the Loca glue (light activated optical clear adhesive with no yellowing and a refractory index below 1.5 and prob. Rhos certificate?) or even how to do it Yourself (diy) a debubbling/vacuum machine for the OCA glue (heat activated one). No need to Google it, You may find out by accident & etc.
Oh! Allways inform for safety precautions by e.g. 2 professionals or something. If You open up a device with a high voltage capacitor, it could be still charged! And whatever I did, I tried allways to avoid handling 220Volts and to put it through a good isolated converter first instead to e.g. 12V
Yeah.. syntax..
I'd like to use a fiber to measure temperature inside a microwave kiln.. at least that's the only way I could imagine doing it... I have no idea how...
I think you can use the collimator from the SFP module
for example, you can see it here
czcams.com/video/vMP9gLMWHhI/video.html
I might might give that a go. I have a similar module (Laser diode direct to fiber) it has a GRIN lens in it, and looks like it was glued into position at the factory, but it would be nice to get a super compact coupler.
Where's the video of measuring magnetic fields etc as promised at the end of this video?
It will come, I have just had so many projects on at the moment, and I need the bench space. I wish I could do this gig full-time!