Intro to DIY Raman Spectroscopy

[@978mississippi]

This is really cool. I had seen in the peer-reviewed literature some proposed designs, but had never seen a video of someone actually doing it. Given the cost of Raman spectrometers, I really congratulate you for helping the community of keen curious mind have easier access to scientific exploration by making their own normally prohibitive devices!

[@jaimebondoza3710]

there's a few more videos out there take a look around people have been making moves on this one

[@jaimebondoza3710]

looking forward to having one on my phone level

[@matthiaswandel]

Love learning about science this way. An explanation, and a homemade apparatus to demonstrate it!

[@Shanjaq]

he's "pretty Stoked" about his Raman Spectrometer. well played Sir :)

[@among-us-99999]

I love how even your 7 year old videos are of great quality.

[@ItsaStringThing]

This is amazing. Also seeing how you built this device helped me understand how Raman spectroscopy worked. Thanks!

[@davemarm]

Wow, DIY Raman Spectroscopy. I can't even do DIY Ramen Noodles. Your videos never cease to amaze me. Keep up the great work. You are an inspiration.

[@ErasmusHaarlock]

A very nice video and kudos for making your own Raman spectrometer! A couple things to say since I do Raman spectroscopy on an almost daily basis. I always try to go with the shortest wavelength possible as a shorter wavelength will give me the greatest signal because the Raman scattering intensity goes like the excitation wavelength^(-4). If fluorescence is problem, then I'll switch to my redder wavelength. It all depends on the sample. There are other ways of getting around fluorescence such as the technique of photobleaching for example. In any case, I'm not sure if this was brought up in any comments previously, but even without your IR filter on your DSLR detector, your detector might have a very crappy detection efficiency out in the near IR. Hence, you might have to leave the shutter open for quite a while in order to get signal out towards the near-IR. If you happen to have a shorter wavelength laser around your shop, I'd put that into your system and try it out. Even a 532 laser pointer might work if the bandwidth of the laser isn't too broad.

[@captkirkconnell]

Dude you really do a good Job. Great channel. You should get some sort of Presidents award. Not only are you delivering very practical scientific educational material but your topics are really cutting edge creating future inovations. True Competence and a very good person!

[@ElectronicTonic156]

Ben, your projects never cease to amaze me!

[@harrysharma1]

I use Raman spectroscopy every day, Renishaw Invia at 514 nm and 786 nm , I had no idea about the working of spectrometer until now, thanks, you are very intelligent sir, I wish to be like you :)

[@quadricode]

Props for using the open source Octave software. It helps to see people supporting open source mathematics packages, even for leisure.

[@miktoyou]

We will never bore of any of your experiments Ben!

[@srenstrke5469]

Hey, great video and nice simple setup. The reason you can't see the stokes/infrared lines is because of the Bayer filter on your camera. You can remove the IR filter, but the RGB Bayer filter is in theory just 3 bandpass filters passing red, green and blue. there is some vague transparency in their IR part (hence the need for a secondary IR filter), but very low compared to the transmission in the visible spectrum. Hope this helps.

[@omsingharjit]

Hot glass filter

[@youskeff]

With 30000+ subscribers, you'd think wrong by orders of magnitude. We love this stuff and we love you!

[@AppliedScience]

Yes, I've been thinking about DIY MRI for a while -- especially since I used to work with commercial MRI machines for my previous job. My friend, Alan Yates is also thinking about it, and we may end up collaborating. It's a really good project, but most of the difficult part is the phase-encoding and math involved with 2D imaging -- not my specialty.

[@meowsiangkhor1]

if you need any filters, please contact us GF Technology [e-mail]

[@GeoffryGifari]

bruh how on earth do you even get the parts for a homebrew MRI?

[@dtiydr]

@@GeoffryGifari Easy, you just build the stuff you need your self not harder than that. If you do DIY MRI you don't do full scale for a human but much, much smaller for much smaller stuff then its much simpler.

[@kondiktor1]

Excellent video. Explained all concept in 10 minutes, including experiment. I can't wait for follow ups.

[@PhilTaylorPhotog]

Very nice results. I understand the time you put in here. One reason why you're experiencing so much noise is that (from your info) you haven't normalized your camera. The pigments used in a Bayer array will have gaps in the spectrum. Also, sensors (silicone) are far more sensitive to IR than shorter wavelengths, so to create a realistic image, the blue channel and possibly green have gain applied to level them somewhat with the red channel. This calibration can be done at a certain colour temp, and it may be different to your tungsten. You have also confounded your problem by removing the IR filter, since the debayer algorithms which help present a realistic (correct spectrum) image, take into account this filter. Once you remove it, more spectra reaches the sensor and the manufacturer algorithm cannot deal with it. If you can normalize your DSLR to some extent (including lens) you should theoretically get a cleaner result. Hope this helps.

[@nth2tell]

I know this video is old but I just found this and I wanna say you are BRILLIANT!

[@GO4Evar]

I'm completely blown away. I don't understand all of this, but I'm subscribing because you're doing excellent work!!!

[@imgingi]

Wow... Worked with these devices in the past... It's nice to see the details of how they work....

[@zander46]

This is so ridiculously awesome! Well DONE! Great results! :). I look forward to your updated version!

[@AppliedScience]

Yes, if you only want one half of the Raman signal (either Stokes or anti-Stokes), you can use a longpass or shortpass filter that blocks the laser line, but allows everything higher or lower.

[@Orbis92]

Very impressive. Thanks for this video. I wish we did such experiments back in school. I have to add yet another project on my never ending list.

[@sajeshthomas7995]

Man, this is simply brilliant! hats off. You must be a scientist. By the way Raman spectroscopy is named after the Indian scientist Sir CV Raman, who discovered Raman scattering in the 1920s.

[@mikeselectricstuff]

Did you verify that the other lines weren't spurious lines from the laser ? You can get green and yellow HeNe tubes, and it is sometimes just possible to get some lasing at these lines by adding additional optics to a red hene tubes.

[@Tower0fHeaven]

You are always a great motivator like i look at what you do and then get motivated to do something.

[@zonderafspraak]

Wow, truly phenomenal. It never ceases to amaze me how much you can do with so little. Well done!

[@One-jz6sl]

I read about Mr. Raman and how he discovered the shift, but until watching your video I couldn't see how lasers could measure the shift or what it was used for. Thank you much, I just bought a nice used S2000 Ocean Optics NIR spectrometer off of ebay which goes from about 1090 nm to 1400, should be able to do something with it, I'm adding more UV-VIS spectrometer cards to it as slave cards which will allow the ability to measure a total spectrum of 350 through 1400 nm with better than 1 nm resolution. I bought the spectrometer cards to measure laser diode wavelengths, just to characterize their wavelength, but being able to use it with a Raman setup might happen someday.

[@EddieVanHalen1977]

I liked it when he said that the Raman effect has nothing to do with the noodles, which was my next question. It was like he knew I wanted to know about that. Nice touch.

[@Romenadan]

Absolutely fantastic! I started researching Raman Scattering when I got my multi-line Argon Ion laser, and was very tempted to try making a basic setup like yours, but I was deterred by the high cost of optics needed for even a simplified version of yours. The diffraction mirror alone would run close to $200.

[@BluefanNL]

One very important aspect: did you filter out the bore light of the HeNe laser? There is a bluish glow coming out of every HeNe laser which contains all the He and Ne spectral lines. These will probably give WAY more signal than the raman signal. Compare your spectrum against the lines of Ne and see if you're catching those instead of a raman signal.

[@spiderjuice9874]

Agreed: there is I believe a green line in the Ne spectrum.

[@jafinch78]

My first thought was why not charactize the waste beam of the beam splitter with another equivalent calibrated to profile and correct for detector "camera" I guess so to perform a spectral subtraction process... I guess easiest would be digital... though I am wondering about comparing processes losses to be able to perform optically potentially with an optical train inverse signal subtraction method.

[@cryora]

@@jafinch78 You'd kind of have to guess how much of the laser spectra is in the signal, in order to determine a multiplicative factor for the waste beam to use as background. Then there's also background noise (such as dark counts) that may or may not be the same in the detector viewing the waste light and that viewing the scattered light that ends up getting multiplied. And then there's other processes like Rayleigh scattering and Mie scattering that exists in the scattered light that you want to get rid of but won't appear in the waste light. I think filtering the input laser with a bandpass to purify it and then using a notch filter to get rid of it is easier to do. I'm not familiar with optical train inverse signal subtraction, however.

[@meowsiangkhor1]

if you need any filters, please contact us GF Technology [e-mail]

[@scotttaylor215]

Really like this, got some good information. I have an old Raman system at work and you help explain some of the details very well. The one we have uses a 1040 nm laser. It's used for student labs.

[@madhatte73]

The hazmat guys where i work have a Raman device which I am told cost about 30 grand. This is a pretty neat way of bringing the cost of entry way down. Props!

[@RimstarOrg]

Awesome experiment as always! I hope you try it with a lot of other materials too. It'd be fun to see. (Now I'll do a search for octave. :))

[@gamingSlasher]

Very interesting, never heard about it. You are excellent at explaining complicated things. Good luck with further improvements.

[@unvergebeneid]

Thanks a lot for the explanation and the search term :) I only knew of absorption and emission spectra in astronomy. Very interesting to hear that there are even more ways to figure out what stuff is made of that's incredibly far away.

[@eastofthegreenline3324]

This is a terrific DIY science project and very well explained. Thanks.

[@gwagner3446]

Thats really amazing, Ben! It is so nice to see how you apply many different concepts of physics in your projects and how the results are really close to academic-grade data! With regards to the noise caused by external light reflections, interference etc, you could actually make a short movie and use a program to stack the frames and enhance the quality of data...

[@smallmoneysalvia]

Props for the TI-80, my favorite TI calculator. I don’t know why, it’s just a charming little underpowered calculator.

[@narongcham3157]

Wow, .... you are a genius, I am glad I found you.

[@AppliedScience]

I'm pretty sure the IR filter in a camera is not nearly sharp enough to catch the Raman spectra while rejecting the laser line. This is why the very sharp (narrow) filters are so expensive. However, I believe Raman spectroscopy is possible with decent IR laser diodes.

[@kaugrego]

Many raman systems use a 90 degree setup like the one you described. The backscatter configuration is neat, though, because (1) it enhances the spatial resolution; (2) it's easier for measuring spectra of liquids (I've never heard of any professional 90 degree raman setup having difficulty measuring liquid spectra, but I couldn't get this to work in my DIY setup); and (3) you're half-way there to building a raman microscope. Granted, beamsplitters lessen signal strength and introduce noise.

[@AppliedScience]

I agree. This is a good plan to get more signal out of the system.

[@KeenanTims]

awesome experiment. you've got a knack for finding a good balance to quickly introduce a complex topic without boring in details and the demos are always great. thanks, always look forward to your posts :D. i think your optics are probably blocking most of the IR much beyond visible, and not sure the camera sensor will detect it either. i know IR cameras have expensive germanium optics for this reason, and the specs on the filter list 845nm as the lower limit, very close to visible.

[@CheapDeath96]

Eeyyyyy "Optics" is nice play list to listen in my autistic sleep. Thank you Ben for feeding my autism.

[@omsingharjit]

1:15 it seems it's doing frequency doubling just like non liner crystal ? Does it also conserve energy ?

[@wcamilo96]

Pretty cool, thanks a lot! Do you guys know of any international program to reuse old lab materials in developing countries? Best regards.

[@AppliedScience]

It's a good question. If everything were perfect, we could use only the diffraction grating to separate the original laser line from the Raman signal. However, in the real world, the stray light and scatter from the laser line is so much more intense than the signal, it will overpower everything inside the spectrometer. Professional equipment uses better filters to avoid losing to 30nm.

[@ahbushnell1]

When I was in school I did work in spectroscopy and I used a double spectrometer that was designed for raman spectrometry. There were two spectrometers stacked on top of each other and connected in series. This was needed to get the signal to noise to see the lines that are close to the powerful source.

[@deangouramanis7164]

0:45 - Read my mind. Thanks for clarifying.

[@piranha031091]

Wow, man... I now want sooo much to do the same! I am really amazed by each of your advanced science projects, just mindblown. My friends used to nickname me McGuyver, but my skills are nothing compared to yours! Keep up the excellent work!

[@mikeselectricstuff]

good idea - a photomultiplier will give you a lot more sensitivity than a DSLR, and will have a specified wavelength vs. output calibration curve

[@Kini_the_Fox]

I read that as “ramen spectroscopy”. I thought SWEET! I get to see the spectroscopy of my favorite soup!

[@GeoffryGifari]

seems like there's a lot of interference going on around that beam-splitter... does this present a problem?

[@GRAFHC]

Love your videos... always learn so much, thank you for taking the time to do them!

[@sunday4904]

Nice explanation that why we use wavenumber instead of wavelength in Raman spectroscopy.

[@diasyuri]

Brilliant work. I wonder why did you choose to use a notch filter ? you could use a collection lens about 45° to the incident laser light to collect the scattered light from you sample. The Rayleigh scatter will be present but the intensity is less than the first case.

[@JugurthaHadjar]

Can we have a sort of common mode rejection in differential amplifiers with this using the part of the laser light that's wasted in the beam splitter? (the one that goes to the left). Spectral subtraction without the notch filter. The part that "goes to the left" is lost, but it's also a virgin representation of our laser light. We don't let it get lost, we feed it back to a system and compare it against the result of the reflection from the sample. Since both have the laser light component in common, their difference will get rid of what is common, like a differential amplifier.

[@AppliedScience]

The spot size is determined by the microscope objective quality and the profile of the beam as it passes into the objective. In this case, I am just using the beam as it comes from the laser without any cleanup. I'd guess the spot size is 5-20um.

[@randomletters12c]

Ben, you might want to take two images: one with the science target and one without. Then in photoshop or octave you should be able to difference the images and lessen some of the light leaks and internal reflections that you might not be able to remove.

[@frank083]

Amazing work! A sugestion: if you want to see the red shifted spectra really close to the excitation beam, you can do it with your 30nm notch filter. Just tilt the filter a bit and the rejection band will shift to the blue according to lambda_cut_new ~ lambda_cut_old * cos(incident_angle). Maybe you can see some close lines!

[@Forssa1]

Very interesting. Please keep us posted.

[@Muonium1]

Warning - there is no turning back once you have been bitten by the spectroscopy bug. The tremendous depth of information that can be retrieved from spectra is POWERFULLY seductive.

[@sodemoot]

If only my science teacher knew I would end up watching these videos 25 years later after he flunked me. He would be sooo proud of me :)

[@costarich8029]

Could you catch the 'waste' light going to the left and recombine it out of phase to remove the need of the notch filter?

[@yellowmetalcyborg]

Great stuff! I never though this kind of thing was possible within the confines of an amateur lab. Among chemists, IR spec. is also very popular. The main issue with making an IR spectrometer, is that it's difficult to make a tuneable IR source, and the output signal is susceptible to noise (if the sensors are not cooled). Many have tried and failed...

[@dimastorres8530]

Amazing. I have to use a raman microscope next week. I would be glad to help you make one if you like

[@LordMejdi]

Hello, I know it's late (8+years :D) , and you probably found the answer by now... But you don't see the IR in the spectrum because your camera's CCD are Silicium photodiode. Bandgap 1.1eV = 1 100nm. So you can't see bellow 1 100nm (even without a "hot glass" filter or a Bayer filter). Cheers!

[@SciDOCMBC]

Are there any updates on this project? I find it extremely interesting. Thanks for the great video.

[@victorhugocarreira1908]

Hey dude, say hello to Brazil, great videos

[@ukaszjozwiak9468]

I have been looked for that HeNe laser but they are quite to bit expensive. It is possible to use a much cheaper green alternative hi power laser diode instead? 8:00 too much effort in my opinion, some months ago I wrote my own software to do such a things. But that options had also some free software as for example Menges Spectragryph :). 8:59 please consider that you dont have a reference polistyrene but some kind of "product", especially that kind of analysis is mostly surface analysis, so also they may be some anti-adhesives for styrofoam mold added. Maybe some silanes or another stuff.

[@Rolltides-Det.L]

This is cool!I wonder if I have the honor to learn about the software you wrote? My partner and I have been researching this DIY project in recent weeks, but we haven't fully understood the steps about optical image processing in the video...:c

[@kaugrego]

Really terrific work, Ben. I especially like the use of a camera, which eliminates the need for a dedicated CCD spectrometer unit. Have you considered using a tiny mirror on a microscope slide rather than a beam-splitter to avoid the loss of backscattered light as it's returned through the objective? See, e.g. Mohr et al., J. Chem. Edu., Vol. 87 No. 3 March 2010. I implemented Mohr's design using a $50 532 edge filter off Ebay, which gave decent spectra for aspirin and ethanol.

[@rickswazey9472]

I was going to ask if you had a way to avoid having the stray light in your shop affecting your readings, specifically between the diffraction grating and the camera sensor. But I think I heard you say toward the end of the video you were going to work on removing some of the light leaks in your system. Fascinating work. Thank you for sharing!

[@puddingpimp]

Once the light source is suitably warmed up (so it's not varying significantly over the sampling time) it should be a simple matter to run the rig with the sample bypassed (or removed), sample the spectral profile of a dryrun and use that as calibration data for the sample-in-situ run. the corrected profile will be something like Isample / Ibright. corrections would need to be made for the non-linearity (gamma) of the detector wrt received flux.

[@Ardren]

Came for the noddles, stayed for the spectroscopy.

[@puddingpimp]

I thought it was typical in IR spec to modulate incident angle by rotating the D-grating in a broadband IR beam. Under this regime the signal can be enhanced by longer exposures and slower modulation of the incident angle. Any non-transient signal is resolvable with sufficient time.

[@dmgores]

Hello Ben. Love your videos. In this one, you expressed wonder why you couldn't see infrared. I'd guess its because even though you took out the IR filter on the camera, every piece of glass in your system blocks IR. The glass lenses etc in your system need to be made of germanium if you want them to be transparent to IR. This came to mind from my experience manufacturing IR optical equipment.

[@Kalywonkas]

Yeah! That's exactly how astrophysicists work out the chemical composition of other planets, often they use what's called 'rotational raman' spectroscopy which uses radio waves (Since that's what a cold body like a planet emits naturally) to detect the chemicals present on the surface. Nice one!

[@MaxJusticz]

If you already know the wavelength of the laser, why do you need the laser line filter? Can't you just ignore the portion of the spectrometer output due to the laser's light? I mean, I guess you'd have to find another way to calibrate the scale, but that seems like a solvable problem (perhaps using gas discharge tubes that give off known wavelengths), because having that extra 30nm seems useful. This is really, really cool!

[@BluesDoctor]

Again great work. You will need an image intensifier for the nir signals. These cameras are just not efficient enough for this work in nir. Intellivue camera adapters show up on ebay from time to time. The tube will be burned from sun exposure but likely useful here. Nice part is they are usually cheap.

[@insanitywolf05]

Really cool! Obtaining those raman filters is a pain an therefore I wonder whether you could just attach a self-built linear ccd-based spectrometer and cover the spectral line where the laser wavelength is projected on the ccd with a delicate line of really black paint (black 3.0). Can't you get around the need for an unaffordable notch or edge filter this way? Somebody certainly had that that idea before since it's so simple but I've never seen an answer why this should not be possible....

[@simonRTJ]

Ben, if you can get hold of a holographic grating you will eliminate the ghosting and noise almost entirely, Holographic gratings are used only in Raman exclusively for this reason.

[@AppliedScience]

It dispenses all ingredients to make a cookie, but there is no mixer. I demonstrated it at Maker Faire, then cleaned it up and it's sitting in my shop. If I build a mixer for it, I'll do another video. I think people might be a little tired of cookie machine updates (even I am a little tired of it;)

[@naasikhendricks1501]

Hey where did you get your libraries for Raman and NIR?

[@seditt5146]

Would redirecting the first waste beam onto the spot potentially produce a stronger signal? I know in theory it should not reflect back properly however no surface is perfectly smooth so the second beam should create a stronger signal.

[@diasyuri]

If you use a long or shortpass filter you´ll still need to use a beam splitter. But if you use a dichroic mirror, you can eliminate the beam splitter and have a better signal to noise ratio once your raman signal is won´t be divided by 50%.

[@yellowmetalcyborg]

I'm not an expert, but one issue with using "broadband IR" is that the intensity of each wavelength of IR varies with frequency if you use a black-body source. You would have to factor in some kind of distribution to eliminate signal distortion. If you use LEDs as IR sources, the IR is confined to a narrow set of wavelengths that are of equal intensity. The issue with IR diodes is that they are typically not tuneable, although their output frequency can change with temperature.

[@Fake0Name]

Did you consider using something like a monochromator? It seems like a monochromator with some sort of automated servo and a photodetector would be an easy way to measure a low-intensity signal close to a high-intensity source.

[@Muonium1]

I don't know if he's still reading these comments but this actually IS totally possible for him to do without any cryogens or anything. The images will be poor but he COULD do it with some relatively simple solenoids and electronics that are obviously within his means of constructing. I'd love to see it done.

[@TheTarnogorski]

A demonstration video would be fantastic!

[@faraonlatino]

amazing! how cool to make your own Raman spectroscopy device!

[@mikelwrnc]

Could you use the “waste” beam interferometrically to filter-out the emission wavelength more efficiently than the notch filter?

[@puddingpimp]

I don't know how you would accomplish gamma calibration except by reference to calibration data supplied with the detector or datasheet. I suppose one way would be to reduce the intensity of the illumination with an adjustable iris or filters of a known attenuation at a specified wavelength. Adjusting the power to the IR light source is very likely a bad way as most or all light sources are non-linear with respect to input power.

[@thrustin64]

Easiest thing would be to do the measurements in dark conditions. You could add a TE cooler to the camera sensor to reduce noise as well. Also having a hole in addition to a slit may help.

[@yellowmetalcyborg]

I see. I didn't think about that. That makes a lot of sense. You could also sample the spectrum with just the solvent, and then sample again with the solvent and analyte.

[@dean._.0.0]

Would you be able to describe some of the hurdles you had to overcome. You mentioned you had been working on the project for a few months, would love to hear what changes and breakthroughs were needed in your DIY setup to get signals. How are you taking the images, long exposure?, etc?

[@Keith_Ward]

Awesome work Ben!

[@jlfqam]

Hi, Raman signals fall in the infrared as the energy ( lambda) of the scattered light is smaller (longer) than the excitation. Any shift towards higher energies will not produce signifcant color change as the energy levels involved in Raman dispersion transitions are due to vibration states that have much less energy gaps than emission involving electronic state transitions. I encourage you to use a CCD detector to find the Raman lines in the IR range.

[@fuckthisshiat]

not necessarily, you have both stokes and anti-stokes shifts, the lower energy photons are of higher intensity simply because of the higher population density in the ground state.

[@jgmrequel]

He states that he removed the infrared filter in the camera, so he is getting those wavelengths.

[@Fake0Name]

Supposedly you can get about 1000X attenuation of non-target wavelengths with a monochromator. It may still need the notch filter, but even with the filter, a monochromator could still be useful for precise measurements.

[@zurkog]

Ben - Would it be possible to use an additional laser of a different color, and an appropriate notch filter, and then combine the data between the two scans to get a more complete picture?

[@atenrok]

I was wondering about the same thing. He has a diffraction grating, why does he care about additional filter?