DIY Tunable Dye Laser! (HD 60FPS re-encoded video)

[@danriches7328]

Love your videos Les, can we have a breakdown of the dye cavity with mirror positions and notes on what can be used to build a DIY version please? Keep up the great work, I'm looking forward to more of your vids with great anticipation. Your breakdown of the N2 laser especially the spark gap was invaluable as I'm sure many have fallen into the trap of this part not firing fast enough!

[@LesLaboratory]

Thanks. Sure, when I get time I could do a video specifically on the Dye Laser. I have been wanting to do one will each of the Dyes anyway. I'm just about to replace one of the mirror mount screws with a miniature micrometer head I picked up! Cheers!

[@dsvilko]

This is extremely cool! Must add it to the list of things to make.

[@LesLaboratory]

Do it! It is well worth it! In my other videos, I detail the TEA Nitrogen Laser that Drives this Dye Laser, please do check them out!

[@SenpaiSkyy]

Hi there, I was wondering what kind of mount you used for the ThorLabs Gr13-1205 Ruled Reflective Diffraction Grating. Also wondering about the part numbers or names of everything you didn't build in this video. If that is too much maybe a video or video link on what all the laser equipment names or what they are called and what not is used. I am very sorry to ask so much but I do want to learn more and do more with this "Hobby".

[@LesLaboratory]

Hi, happy to answer questions.I used second hand (eBay) Newport MM-1 Mirror mounts for both the grating and the output mirror. They are nice small 1 inch mounts. The Cuvette was a 10mm path length Quartz cuvette (eBay) The Cylinder lens was bought some time ago from Edmund optics, and is also Quartz, and the mount on which it sits was again from eBay. The base plate, and cuvette holder, and lens holder are home made. I suppose with adequate tools and patience, all of the mounting hardware could be hand made.

[@SenpaiSkyy]

@@LesLaboratory thank you so much for the replies. 😃😃

[@Jimmymcjimthejim]

Excellent video. Thank you very much for sharing.

[@LesLaboratory]

Glad you enjoyed it! There is more to come...

[@petevenuti7355]

How are visible pulses of air ionization achieved? Is any combination of frequencies best for power efficiency and range in that application?

[@weirdsciencetv4999]

If you combined multiple dyes in same solvent, could you get continuous wavelength coverage in the visible spectrum?

[@LesLaboratory]

Kind of, but it does not work very well. As well as emission spectra, dyes have absorption spectra. If the two overlap from different dyes then it suppresses Lasing.

[@weirdsciencetv4999]

@@LesLaboratory thanks! Your designs are elegant! Def the best N2 lasers on the block!

[@LesLaboratory]

@@weirdsciencetv4999 Thanks! :-)

[@Zenodilodon]

You could also use a prism in the beam path between the cuvette and the HR to tune the laser color like in an ion laser if you have a broadband HR. It may make a better beam compared to diffraction grating.

[@LesLaboratory]

I have in a previous version, but there is a catch! The prism needs to have high dispersion to effectively tune,, plus it's yet another element to align. In some Dye Lasers, they stack prisms to get the required dispersion. The garbage in the beam is mostly due to reflections and refractions from the cuvette, the reflection from the grating is actually pretty clean. The beam could be cleaned up with a spatial filter. In Argon Lasers you can get away with a littrow prism for 'tuning' because you are only selecting lines rather than real tuning.

[@Zenodilodon]

@@LesLaboratory That makes perfect sense. Dyes do have a much broader band range than atomic emission does. I had thought you may of been getting additional orders from the diffraction grating and losing some power and beam profile. Spacial filters do a good job of cleaning up a beam but it's usually a last resort thing it seems. I like to try to get out noise in other areas before doing that, It just seems like a frosting on the cake kind of deal. I am just getting into dye laser stuff myself and have been collecting dyes for future laser projects of interest.

[@LesLaboratory]

@@Zenodilodon Agreed! It would be best to attain a clean-ish beam first, so save on losses later. The additional orders scatter away from the Cuvette, but do represent a loss of power. That said, with an un-coated prism, I would still lose around 8% of the beam to reflections as well. When the beam from the dye laser is allowed to expand and is projected some distance away, it appears as a main spot, with magnified image of the Cuvette wall from scattering. The main 'spot' appearing an almost triangular (tear drop shaped) beam profile. It is likely that lowering the dye concentration a little and de-focussing the pump bean a little, might result in something a little cleaner, but without external optics, I don't think I will ever see Gas-Laser-quality beams out of it. In 'real' dye lasers a number of techniques are used to get high efficiencies, narrow line-widths and high powers. I was looking at MOPA configurations in academic papers a while back. The incoming N2 Laser beam is split in to two, one pumps one Cuvette as a Master Oscillator (MO) and the other pumps a second Cuvette as a Power Amplifier (PA) They were using grazing incidence gratings to achieve sub-nanometer linewidths from the Master Oscillator, and its output beam was directed though the beam path of the Power Amplifier. (see page 8 of this for a diagram of something similar: dewan.buet.ac.bd/EEE6503/Reports/Report_Chap14_TunableDyeLasers.pdf Cheers!

[@Zenodilodon]

@@LesLaboratory Laser reading is good reading.I will certainly look at that PDF, probably save it too. If you are looking for laser documents I have a few good ones saved and I would love to get more for my collection. Let me know if you want to exchange reading material!

[@Zenodilodon]

@Les' Lab the URL is 404/unavailable check the hyperlink please.

[@sumguysr]

I'd love to see if this can be used for a raman spectrometer

[@LesLaboratory]

It might be possible. I have been thinking lately of doing something new with Dye Lasers!

[@georgegreen3672]

So the reflective diffraction grating can reflect light back through same path, just as the other parallel mirror of F-P cavity.

[@georgegreen3672]

but from image of google, it seems there is no such reflective direction.

[@LesLaboratory]

Yes, exactly, the difference is, by tilting the grating one one axis, you can select a specific wavelength of light.

[@georgegreen3672]

@@LesLaboratory Yes, it seems that a special color light beam reflects back throuth the incident path.

[@georgegreen3672]

@@LesLaboratory what's the name and parameter of the left-side mirror and optic base/bench?

[@LesLaboratory]

@@georgegreen3672 The left mirror on the Dye Laser? This is a 50:50 economy plate beamsplitter from Thorlabs: www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=914 Feedback in these lasers is very high and almost anything will do.

[@davidrosengrant9129]

Can you tell me the mixture in the cells you lased. I have a working MNL 100. I've got some rhodium (two flavors) I'd love to make a jello laser.

[@LesLaboratory]

Don't eat Rhodamine, it is toxic and carcinogenic! I used Rhodamine 6G in methanol in this dye Laser, I forget the concentration (I am away from the Lab) but it was a tiny amount.

[@philipbrenan1091]

If the sides of the metal rails in the laser channel were even sharper might this increase the power density of the beam ? Going from square, to round, to hexagonal ....

[@LesLaboratory]

I tried many profiles and found that sharp edges tend to generate sparks in the channel, reducing output. With rounder electrodes, I found that the discharge looks very smooth, but output is very low. It seems you need to strike a balance in the channel where the electric field strength is high enough to effectively couple the power into the gas volume, but not so high as to generate sparks in the channel.

[@jonnyreverb]

Can you make a T.E.M. 00 dye laser with a long coherence length for ise in holography?

[@LesLaboratory]

It is possible to get TEM-00, if the dye cell is longitudinally pumped.

[@Gianns_TDM]

Ok, I'll pull the trigger! Can you give me a components list for the optics you used from Thorlabs and how much it costed? I am just now getting into dye lasers, My specialty mainly is diode and dpss lasers, Been meaning to get into dye and gas lasers for a while.

[@LesLaboratory]

For Thorlabs I bought the following for my Output Coupler and the diffraction grating: GR13-1205 Ruled Reflective Diffraction Grating, 1200/mm, 500 nm Blaze, 12.7 x 12.7 x 6 mm £53.36 EBP1 Economy 30:70 Beam splitter, Ø1", AOI: 45° £26.18 The Fused Silica Cylindrical lens I already had in my collection (used it in a nitrogen laser project I built as a kid) and is PCX with a focal length of about 30mm or so. Fused Silica optics are very expensive, not much change out of £200! You could perhaps substitute BK7 Glass, and perhaps spend 70 bucks. The mirror mounts are Newport MM-1 mounts that I bought off eBay for $80USD for the pair plus shipping. The linear stage, was also an eBay find, about £30 I think. Cuvettes I get from eBay. You need the 4 window versions (3.5ml 10mm Path JGS1 Quartz Cuvette With Stopper For Fluorescence Spectrometer). Expect to pay about £30 from China, but buy brand names if you can get them at a reasonable price (I bought Hellma cuvettes for £60 each) The rest is just aluminum plate, aluminum bar and an old cctv lens housing figure about £30 for this stuff. All in, you are looking at somewhere upwards of £350, though you could do it cheaper if you are patient on eBay and have an eye for a bargain!

[@Gianns_TDM]

@@LesLaboratory for the collimator I think that I will try using one that I use In most of my diode lasers, Its an AR-coated long focal point single collimator named G8 that is AR coated with broadband 400-700mm. Its pass efficiency has been measured to 90%. Have you measured the power output of your dye laser?

[@LesLaboratory]

@@Gianns_TDM Your lens will need a pretty long focal length. Mine is about 48mm. I have not measured the output of the Laser as I would need a Laser energy meter rather than a regular power meter to measure it. My best estimation based on the N2 Lasers ability to threshold a bare cell, is that the N2 peak power is about 300-400kW (30-40mW at 20Hz) and the Dye under ideal conditions will generate in the region of 10mW average power at 20Hz and maybe 100kW peak. I really must get hold of a joule meter!

[@Gianns_TDM]

@@LesLaboratory Mk seems good! Its getting in the list of to-do after i do some component hunting, Thanks!

[@hullinstruments]

@@Gianns_TDM hey there Giannis, any update on your progress? had any luck locating components at an affordable price?

[@drrenard1277]

Sucks for me, I am monochromatic. Fully colour blind

[@LesLaboratory]

Sorry to hear that. Makes me grateful I have what I have.

[@knglaser]

Brings back memories (: I did some N2 lasing some 10 years ago and aimed for the low pressure path. Did not make a tuneable resonator as I lacked the funding at the moment. I've stored them on flickr.com and you should be able to find them with this addition to the url: /photos/knglaser/albums/72157626250500618/

[@LesLaboratory]

Awesome images! It's worth the time and effort to make it tunable. My first N2 Laser was also a low pressure design, using doorknob caps. I still have it somewhere but it is pretty crusty now. I might revisit it because unlike TEA they really scale up!

[@zhilihuang6609]

I just checked your project, and it's very cool!