Awesome stuff! Your videos always bring back memories for me - I used to work with Raman, UV-Vis, fluorescence and photoemission-spectrometers a lot during my PhD
Hello, You might notice that the barium sulfate is water absorbing and with time (and the PVA glue) your reflectance levels might decrease. Aluminium oxide (that is used in commercial paints) might be another option. Something that would be a great addition would be vacuum forming a PTFE sheet in your sphere. Also, you might be keen to sand (300 grit as per ASD) the inner side and paint to have a lambertian (uniforrmely diffused) surface.
Always interesting, this took me down the surface route and I was reading why "Matte" surfaces are Matte and its not straight forward, it explains why good matte paints are a bit more expensive and also why Matte Green for PCB's is not widely available yet and is expensive when it is offered, great stuff !....cheers.
Yeah, these things send you down rabbit holes! Some formulations for painting spheres require that when the last coat has just been applied, you sieve dry Barium Sulphate on to it for the ultimate matte coating!
That went together really well. I was also having issues with spectrometer measuring and I have been seeing how sanded metal surfaces and frosted glass diffuse the beam. I could see making one of these Ulbricht spheres and having an iris and SMA connector attached to it.
Thanks, it was a nice build. For sure, you could mount an SMA fiber connector on it. It would probably make it more efficient than mine. Large apertures waste photons.
@@LesLaboratory Hey Les, I just wanted to tell you that since I started looking at your Videos, and enjoying the Simple explanations to quite Complex arguments, paired with the genuine enthusiasm and the catchphrase "Absolutely Fantastic!"... I started thinking I could make my own optical bench Fluorescence Microscope,( I worked the past 3 months with a Confocal and a LSFM for my Bachelors Thesis), and I have just bought a 3d printer for my birthday to print the lens holders and possibly an XY Stage based on a flexture design and cheap Micrometer Screws. I just wanted to tell you that Your Videos Really Inspired me and I keep coming back to them when in doubt about the best way moving forward. I wish you All the Best and Thank you again for the great Content!
@@nikolaiturcan6963 Awesome! I'm so glad people find this stuff so useful! That's sounds like a very cool project, I hope you publish it online somewhere ☺️ I have plenty more cool stuff in the works!
I made a similar sphere, but for a different purpose. For uniform illumination of the film. Barium sulfate is very difficult to grind into a homogeneous substance. You need to make a bead mill and load barium sulfate and PVA into it. But for a single use, you can grind with a pestle in a mortar with a small amount of glue, and then dilute with glue to the desired consistency. Les, have you tried doing holography with your color lasers? I think it's very interesting. I also want to make an N2 laser and I have everything for this.. But I don't have the opportunity to buy a quartz cylindrical lens and mirrors. Because of this, I am very upset. Do you know where you can get such a thing?
Cool! I got my cylinder lens from Edmund Optics, but it was expensive at around $80. You can however find suitable Cylinder lenses in Laser printers. They use them to shape the laser diode beam, and although not silica, they are transparent enough that they will work.
For sure. I found an auto paint manufacturer in the UK (Steyer) that does a hard wearing acid etch primer that goes on like silk. I use the stuff for everything.
Repurposing a cannon ball mold makes a much better and less expensive integrating sphere than the one I blow molded from Plexaglls or made by using Plaster of Paris to make a mold of a large ball bearing, then painting the cavities with the same one percent PVA and Barium Sulfate you used. The Plexagals integrating sphere functioned as well as a metal one, but the cost of making a fixture to blow mold the hemispheres and learning to blow good plastic hemispheres at 325 F. Then mating two hemispheres to form an acceptable sphere and finding a primer and surface finish for Plexiglas that homemade Barium Sulfate paint would stick to cost a great deal more in labor than $40 to $100 USD the cannon ball mold would have cost. Plaster of Paris cast over a ball bearing is quick and cheap, but it absorbs humidity and is not compatible with lasers with much power at all. Steam explosions in the walls of the integrating sphere will mess up a lot of stuff.
Yes, you are exactly right, it is ASE! This happens with the Rhodamine as well (although in the green) It is possible to get rid of it. It is not as coherent as the main beam, and appears mostly as side beams that you can nip off with an adjustable Iris. A small Lathe project I did was to make a post and holder for a small Iris I bought off of eBay, and it works really quite well.
Thanks Les, great vid. Some questions: a) I saw wisps of smoke at various points in your vid - what's that all about? b) What beam power can the sphere accept before being damaged? c) Great to know the simple formulation of indoor barium sulfate paint, but what would your viewers need to do for a 'How to make barium sulfate outdoor paint at home' video? I want to keep my shed cool in the hot Aussie sun 😀
You are welcome! So answers in order: a) Smoke is for effect, everyone loves to see laser beams, and it helps illustrate things, so I waft a bit of Majcan about the place. b) I have not measured maximum power that the coating can withstand, the Dye Laser deposits energy in the order of millijoules in a couple of nanoseconds, so peak power is a few kilowatts. As for average power, I guess maybe a couple of watts or so before the binder starts doing strange things. The melting point of BaSO4 itself is over 1500 C. c) I have not really considered this, and I am not entirely sure. The authors of this paper: pubs.acs.org/doi/10.1021/acsami.1c02368 used acrylic as a binder, which makes it still essentially a water based paint, however they did successfully use it outdoors. I suppose when it cures, assuming rainfall is infrequent, it probably wears quite well. I think an acrylic base is probably inexpensive, and Barium Sulfate is probably very cheap in large quantities too, so there would be no great loss in trying it. Unfortunately I live in a very cold and wet corner of the world, so I would be unable to test it out.
Your description of the integrating sphere makes me wonder, can it act as an optical pulse time stretcher? A pulse enters and starts bouncing around, some paths are longer that others, so the light in an individual pulse takes longer to exit, than its duration when it entered. Hmm, 2 centimeter sphere? Transit time of ~67 pS. You mention that the laser pulses are ~2000 pS long, so a 10 % stretch would be about three or four transits of a 2 cm sphere. Have you an o'scope and detector fast enough to measure your pulses? does the sphere stretch them out?
I don't see why not, the problem is I no way of measuring it. My Fastest Scope is only 100MHz. I would need either a much faster 'scope or a streak camera to do stuff like that.
May I ask you a question? Sorry in advance for my English. Since the laser was diffused inside the Ulbricht Sphere, may I say that the laser that comes out is a diffuse ray? It lost the temporal coherence but still has spatial (the wave length is invariant)... Is it right? Is it less dangerous that the previous laser? Thank you.
Yes, the beam that emerges is diffuse, and loses coherence to a degree (there are more effective ways to de-cohere a beam). The resultant light is not less dangerous. If you stare into it, you are still looking at a light source brighter than the sun.
@@LesLaboratory Thanks a lot. The calculations (for a 3B laser of 1,6 microJ) due to CEI 60825-1 let me consider an irradiance less than EMP. May I did think something wrong?
Wondering what would be a cost effective DIY way to get a nano size range of BaSO4 particles for an even more effective reflective material as is more like the ultra-white BaSO4? Chemical, ablation, other? Great info as always sir. Looking forward to more content.
Thanks! There is a video here of precipitation of BaSO4 from solution (about 1:20 in) ruclips.net/video/Ay6ckBojc_0/видео.html I'm not sure of the particle size with this method though. Drop a message on Periodic Table of Videos channel, I'm sure they can answer that.
@Les' lab .... I would like to ask you, how to get laser's light of different frequency, colour How to change the light's frequency to ultraviolet, or to infrared frequency ?? Thx
Hmm, I don't seem to have them handy, and the link is broken. Really the only requirement is a hollow sphere with input and output ports at 90 degrees, so it should not be too difficult to design. You could probably do in in TinkerCAD.
Nice work as always, Les! Thanks for the upload. I think I can more clearly see why speckle is present in the outputs from some my dye lasers - although the output from a dye like R6G is broad, the edges of this broad curve appear to be rather abrupt and sharp (as distinct from the smooth curve that would result if analyzing the spectrum of light from an incoherent source). Am I correct in this attribution?
You can get good speckly output from R6G of you are using a diffraction grating to tune it. The problem is, the gain of R6G is so high, it is easy to overdrive it (in which case gain will happen with mirrors or not, and so you get very broad emission), even with very small Nitrogen lasers. To attenuate home built N2 lasers, I just add regular glass microscope slides in the N2 laser beam, until I am just at threshold for the dye being used.
Very inspiring! I intend to build a heterodyne interferometer (from sam zeloof) but dont have an optical bench. Do you have any advice regarding optical plates (where to find cheap ones?) I saw some 3D designs from BrendaEM and printed them but i dont know how they compare
I got mine from Thorlabs for 200 bucks including shipping and tax, which I figured as pretty reasonable. I had considered buying thick aluminum plate, and drilling ant tapping it, but Aluminium is expensive anyway, plus the time and effort drilling hundreds of holes. I suppose in a pinch you could get steel plate, ans stick magnets on all your optical mounts....
@@LesLaboratory Thorlabs. I' ve their catalog. Intrestingly, I' ve thought it would have been easier for you to get it from new focus. There are only about four producers worldwide. I've worked wit these breadboards from thorlabs. It's intresting how you change your setups from time to time. Regards@
Really interesting, wonder if one can compress the barium sulphate and use it in a sputter coater.. btw have you seen ruclips.net/video/2C7Hajgg9nU/видео.html i stumbled upon it a few days ago and it seems like a interesting spectrometer and (Free) software as an uppgrade.
Nice! LIBS is high on my wish list of projects. I stripped a tattoo laser head about 10 years ago, and still have the thing. I also build a super inexpensive spectrometer using the Raspberry Pi, the software is free and open source. Take a look here: ruclips.net/video/T_goVwwxKE4/видео.html
_The glue that children can eat and it won't kill them_ Now there is an advertising strapline I would like to see! Excellent video, thanks :~D
:-D
Very interesting, the cannon ball mold was an unexpected but pretty genius starting point, I definately didn't expect that.
With some things, why build when you can find something mass produced that can be hacked into what you need!
@@LesLaboratory wise words!
Until five minutes ago I had never heard of an integrating sphere. Thank you. :-)
Thanks!
Fantastic video Les! Your dedication to home-built optics and lasers is truly inspiring and very impressive!
Thanks! There is much more to come ;-)
Awesome stuff! Your videos always bring back memories for me - I used to work with Raman, UV-Vis, fluorescence and photoemission-spectrometers a lot during my PhD
Thanks!
Hello, You might notice that the barium sulfate is water absorbing and with time (and the PVA glue) your reflectance levels might decrease. Aluminium oxide (that is used in commercial paints) might be another option. Something that would be a great addition would be vacuum forming a PTFE sheet in your sphere.
Also, you might be keen to sand (300 grit as per ASD) the inner side and paint to have a lambertian (uniforrmely diffused) surface.
the main big matter is that PVA glue will eventually develop color centers when aging.
Always interesting, this took me down the surface route and I was reading why "Matte" surfaces are Matte and its not straight forward, it explains why good matte paints are a bit more expensive and also why Matte Green for PCB's is not widely available yet and is expensive when it is offered, great stuff !....cheers.
Yeah, these things send you down rabbit holes! Some formulations for painting spheres require that when the last coat has just been applied, you sieve dry Barium Sulphate on to it for the ultimate matte coating!
@@LesLaboratory Makes sense !
Just amazing to watch your work!
Thank you so much 😀
That went together really well. I was also having issues with spectrometer measuring and I have been seeing how sanded metal surfaces and frosted glass diffuse the beam. I could see making one of these Ulbricht spheres and having an iris and SMA connector attached to it.
Thanks, it was a nice build. For sure, you could mount an SMA fiber connector on it. It would probably make it more efficient than mine. Large apertures waste photons.
Did you ever find the CAD file associated with the paper?
Loved the attempt at the open mouth thumbnail, Great Content Les!
Just poking at the algorithm, but I think it might be a myth. Thanks! :-D
@@LesLaboratory Hey Les, I just wanted to tell you that since I started looking at your Videos, and enjoying the Simple explanations to quite Complex arguments, paired with the genuine enthusiasm and the catchphrase "Absolutely Fantastic!"...
I started thinking I could make my own optical bench Fluorescence Microscope,( I worked the past 3 months with a Confocal and a LSFM for my Bachelors Thesis), and I have just bought a 3d printer for my birthday to print the lens holders and possibly an XY Stage based on a flexture design and cheap Micrometer Screws.
I just wanted to tell you that Your Videos Really Inspired me and I keep coming back to them when in doubt about the best way moving forward.
I wish you All the Best and Thank you again for the great Content!
@@nikolaiturcan6963 Awesome! I'm so glad people find this stuff so useful! That's sounds like a very cool project, I hope you publish it online somewhere ☺️ I have plenty more cool stuff in the works!
I ❤ Les' Lab. Awesome channel. 👍
Good Stuff Les as always :-)
Cheers!
Nice
I made a similar sphere, but for a different purpose. For uniform illumination of the film. Barium sulfate is very difficult to grind into a homogeneous substance. You need to make a bead mill and load barium sulfate and PVA into it. But for a single use, you can grind with a pestle in a mortar with a small amount of glue, and then dilute with glue to the desired consistency. Les, have you tried doing holography with your color lasers? I think it's very interesting. I also want to make an N2 laser and I have everything for this.. But I don't have the opportunity to buy a quartz cylindrical lens and mirrors. Because of this, I am very upset. Do you know where you can get such a thing?
Cool! I got my cylinder lens from Edmund Optics, but it was expensive at around $80. You can however find suitable Cylinder lenses in Laser printers. They use them to shape the laser diode beam, and although not silica, they are transparent enough that they will work.
Just a lick of matt black paint on that mould and it doesn't look the slightest bit out of place on an optical bench.
For sure. I found an auto paint manufacturer in the UK (Steyer) that does a hard wearing acid etch primer that goes on like silk. I use the stuff for everything.
Repurposing a cannon ball mold makes a much better and less expensive integrating sphere than the one I blow molded from Plexaglls or made by using Plaster of Paris to make a mold of a large ball bearing, then painting the cavities with the same one percent PVA and Barium Sulfate you used. The Plexagals integrating sphere functioned as well as a metal one, but the cost of making a fixture to blow mold the hemispheres and learning to blow good plastic hemispheres at 325 F. Then mating two hemispheres to form an acceptable sphere and finding a primer and surface finish for Plexiglas that homemade Barium Sulfate paint would stick to cost a great deal more in labor than $40 to $100 USD the cannon ball mold would have cost.
Plaster of Paris cast over a ball bearing is quick and cheap, but it absorbs humidity and is not compatible with lasers with much power at all. Steam explosions in the walls of the integrating sphere will mess up a lot of stuff.
what's that going on down there at 465nm while the coumarin is lasing at 495? Amplified spontaneous emission?
Yes, you are exactly right, it is ASE! This happens with the Rhodamine as well (although in the green)
It is possible to get rid of it. It is not as coherent as the main beam, and appears mostly as side beams that you can nip off with an adjustable Iris. A small Lathe project I did was to make a post and holder for a small Iris I bought off of eBay, and it works really quite well.
@@LesLaboratory noice! slowly but surely I am still learning how the nature of things is arranged...
Subscribed!
Thanks for your support! :-)
Thanks Les, great vid. Some questions: a) I saw wisps of smoke at various points in your vid - what's that all about? b) What beam power can the sphere accept before being damaged?
c) Great to know the simple formulation of indoor barium sulfate paint, but what would your viewers need to do for a 'How to make barium sulfate outdoor paint at home' video? I want to keep my shed cool in the hot Aussie sun 😀
You are welcome! So answers in order:
a) Smoke is for effect, everyone loves to see laser beams, and it helps illustrate things, so I waft a bit of Majcan about the place.
b) I have not measured maximum power that the coating can withstand, the Dye Laser deposits energy in the order of millijoules in a couple of nanoseconds, so peak power is a few kilowatts. As for average power, I guess maybe a couple of watts or so before the binder starts doing strange things. The melting point of BaSO4 itself is over 1500 C.
c) I have not really considered this, and I am not entirely sure. The authors of this paper: pubs.acs.org/doi/10.1021/acsami.1c02368 used acrylic as a binder, which makes it still essentially a water based paint, however they did successfully use it outdoors. I suppose when it cures, assuming rainfall is infrequent, it probably wears quite well. I think an acrylic base is probably inexpensive, and Barium Sulfate is probably very cheap in large quantities too, so there would be no great loss in trying it. Unfortunately I live in a very cold and wet corner of the world, so I would be unable to test it out.
@@LesLaboratory Cheers Les
Your description of the integrating sphere makes me wonder, can it act as an optical pulse time stretcher? A pulse enters and starts bouncing around, some paths are longer that others, so the light in an individual pulse takes longer to exit, than its duration when it entered. Hmm, 2 centimeter sphere? Transit time of ~67 pS. You mention that the laser pulses are ~2000 pS long, so a 10 % stretch would be about three or four transits of a 2 cm sphere. Have you an o'scope and detector fast enough to measure your pulses? does the sphere stretch them out?
I don't see why not, the problem is I no way of measuring it. My Fastest Scope is only 100MHz. I would need either a much faster 'scope or a streak camera to do stuff like that.
Whoah, that was weird. I work with John & Chris (I look after the department's computers while they do the clever stuff). Small world!
Awesome! A small world then indeed! Their paper was really useful, I love in-house creativity!
May I ask you a question? Sorry in advance for my English. Since the laser was diffused inside the Ulbricht Sphere, may I say that the laser that comes out is a diffuse ray? It lost the temporal coherence but still has spatial (the wave length is invariant)... Is it right? Is it less dangerous that the previous laser? Thank you.
Yes, the beam that emerges is diffuse, and loses coherence to a degree (there are more effective ways to de-cohere a beam). The resultant light is not less dangerous. If you stare into it, you are still looking at a light source brighter than the sun.
@@LesLaboratory Thanks a lot. The calculations (for a 3B laser of 1,6 microJ) due to CEI 60825-1 let me consider an irradiance less than EMP. May I did think something wrong?
Wondering what would be a cost effective DIY way to get a nano size range of BaSO4 particles for an even more effective reflective material as is more like the ultra-white BaSO4? Chemical, ablation, other? Great info as always sir. Looking forward to more content.
Thanks!
There is a video here of precipitation of BaSO4 from solution (about 1:20 in) ruclips.net/video/Ay6ckBojc_0/видео.html
I'm not sure of the particle size with this method though.
Drop a message on Periodic Table of Videos channel, I'm sure they can answer that.
does this reflect infrared too?
It should do. According to the academic papers, reflectivity continues well into the IR.
Goddamned brilliant!! Nicely done!
Do you think I could make a decent diffuse reflector by sand blasting a first surface mirror?
@Les' lab .... I would like to ask you, how to get laser's light of different frequency, colour
How to change the light's frequency to ultraviolet, or to infrared frequency ?? Thx
To learn more about integrating spheres check out the Knowledge Base at www.labsphere.com.
Do you happen to have access to the CAD/STL files for the sphere? Having difficulty gaining access.
Hmm, I don't seem to have them handy, and the link is broken. Really the only requirement is a hollow sphere with input and output ports at 90 degrees, so it should not be too difficult to design. You could probably do in in TinkerCAD.
Nice work as always, Les! Thanks for the upload.
I think I can more clearly see why speckle is present in the outputs from some my dye lasers - although the output from a dye like R6G is broad, the edges of this broad curve appear to be rather abrupt and sharp (as distinct from the smooth curve that would result if analyzing the spectrum of light from an incoherent source). Am I correct in this attribution?
You can get good speckly output from R6G of you are using a diffraction grating to tune it. The problem is, the gain of R6G is so high, it is easy to overdrive it (in which case gain will happen with mirrors or not, and so you get very broad emission), even with very small Nitrogen lasers.
To attenuate home built N2 lasers, I just add regular glass microscope slides in the N2 laser beam, until I am just at threshold for the dye being used.
Very inspiring! I intend to build a heterodyne interferometer (from sam zeloof) but dont have an optical bench. Do you have any advice regarding optical plates (where to find cheap ones?) I saw some 3D designs from BrendaEM and printed them but i dont know how they compare
I got mine from Thorlabs for 200 bucks including shipping and tax, which I figured as pretty reasonable. I had considered buying thick aluminum plate, and drilling ant tapping it, but Aluminium is expensive anyway, plus the time and effort drilling hundreds of holes.
I suppose in a pinch you could get steel plate, ans stick magnets on all your optical mounts....
@@LesLaboratory thanks! Ill try my 3d printed ones out :)
Excellent. What is the diameter of your cannon ball mold? I'm based in the USA can can't seem to find one. Any suggestions?
2 inches in diameter internally. Hmm, try looking for sinker moulds or similar. Some anglers like big heavy weights on their lines!
@@LesLaboratory thanks, I did try that. BTW an excellent channel.
@@DaSmokeDaddy Thanks! Try eBay, take a look at 290809870305, they don't have any large ones in stock, you could always enquire.
I do a bit of home chemistry.... don't think I've ever had any barium compounds
Cool! Most Ba salts are toxic, but BaSO4 is inert.
Kindly respond: where have you got the holed plate from? Thank you!
I got it from Thorlabs. When you are on their site, look for "Optical breadboard"
@@LesLaboratory Thorlabs. I' ve their catalog. Intrestingly, I' ve thought it would have been easier for you to get it from new focus. There are only about four producers worldwide. I've worked wit these breadboards from thorlabs. It's intresting how you change your setups from time to time. Regards@
There are some 3D printed designs from BrendaEM if ud like a cheap option. But naturally they cant compare to the thorlabs ones
Really interesting, wonder if one can compress the barium sulphate and use it in a sputter coater..
btw have you seen ruclips.net/video/2C7Hajgg9nU/видео.html i stumbled upon it a few days ago and it seems like a interesting spectrometer and (Free) software as an uppgrade.
Nice! LIBS is high on my wish list of projects. I stripped a tattoo laser head about 10 years ago, and still have the thing. I also build a super inexpensive spectrometer using the Raspberry Pi, the software is free and open source. Take a look here: ruclips.net/video/T_goVwwxKE4/видео.html
Hi
My name is André necessary construction sphere