OK, looks like people are checking in now, so let's kick things off. Welcome to the Hack Chat, I'm Dan and I'll be moderating today along with Dusan. Today we're excited to welcome Zachary Tong to the Hack Chat -- you've probably seen some of his cool stuff on the Breaking Taps YT channel. Today, we're going to focus on microscopy, though. See what I did there?
Hello and welcome!
I'm not sure I've seen Zach log in yet, though. Are you out there yet, Zach?
Heya! This is Zach / Breaking Taps. :)
@polyfractal thing. Sorry!Oh, that's right -- forgot about the
I looked at the laser microscopy video, it is amazing. You showen how easy it is to make.. still have you considered moving a prism or galvo to move the laser bundel?
Hehe yeah sorry, I'm "polyfractal" pretty much everywhere except on my YT channel :)
Can you get us started with a little about your background?
Sure! I typed up a little background before-hand.
So my background is actually in biology, which might be a surprise for folks that have seen some of my videos. Or maybe not, considering my poor engineering/EE skills hah. I have a degree in cell bio and worked in a wet lab for a number of years (culturing kidney and primary hippocampal neurons, running assays, etc). However for the last 10 or so years I've been in software. Most of that time working on the analytics functionality of a search engine called Elasticsearch.
Anyhow, I started my YT channel when I picked up metalworking, and it's slowly morphed into material science and microfab stuff. As my projects have gotten "smaller" over time, I keep finding myself needing (or wanting) new ways to measure/quantify the projects. Which has led to a proliferation of microscopes in my shop :)
To date, I have a few optical microscopes, a DIY laser confocal, a DIY "macro" atomic force microscope, a real AFM and a raman spectrometer. Contemplating building a chromatic confocal next, or maybe a white light interferometer. Definitely enjoy building instruments, even if they don't end up quite as useful as the real commercial ones :)
@Hexastorm Thanks! Yeah, considering some options to speed it up if I ever do v2. A galvo seems like a good approach, and you can get them pretty cheap (metal etching fiber lasers use them, so they are relatively mass-produced and cheap). A bunch of folks suggested CD/DVD optical units as an option too, which basically has all the guts pre-built and you just have to interface with it
Are you planning on realeasing the code for your LSM?
@perlsackhd I wasnt originally but a bunch of folks have asked, so I'm currently compiling to throw on github somewhere. Need to find a RPi that i've temporarily misplaced :) The code is quite poor though, just quick bodges to get it working and interface with OpenFlexure (i hacked a new endpoint onto their server code)
A couple of links for reference, in case you haven't seen them:
When one thinks about microscopy, it seems to be mostly qualitative. Looking at a slide teeming with bacteria or protozoans is less about making measurements and more about recognizing features and describing their appearance. Not all microscopes are created equal, though, with some being far more optimized for making fine measurements of the microscopic realm.
For anyone that's fiddled around with a magnifying glass, it's pretty easy to understand how optical microscopes work. And as microscopes are just an elaboration on a simple hand lens, so too are electron microscopes an elaboration on the optical kind, with electrons and magnets standing in for light and lenses.
@polyfractal you should check out my video, I have a laser scanner with a fpga . Actually after seeing your video I thought of adding reading
sorta followup on the v2 subject, one variation I'm considering next is a "chromatic confocal", which scans the full Z-stack simultaneously. It's a really clever setup which "abuses" chromatic aberration to determine the height. They are considerably faster than regular confocals if you don't need fluorescense, etc and just want heightmaps
@Hexastorm will take a look after, cheers for the link!
Ist it possible with the your icspi afm to take force curves to get local material parameters?
That's really cool. What special about the "specially designed lens" - designed to maximize chromatic aberration, I suppose?
Doesn't the chromatic confocal get influenced by the color of the sample?
@polyfractal project is here https://hackaday.io/project/21933-open-hardware-fast-high-resolution-laser ... you should also check out the startup spiden.com they have an interest in your work and use light + ai to detect biomarkers, anyhow enough promotion 😉
@lageos I _think_ it can take force curves (i saw mention in the manual) but to be honest I haven't played with it yet so can't really say much else. I think it's part of the advanced config/settings i haven't really touched yet
@Dan Maloney The lense is needed so that the diffrent Wavelengths have diffrent focal distances
@Dan Maloney Yep, pretty much. I think they are known as "hyperchromatic" lenses, but i believe you can also stack up a bunch of spherical lenses and stretch out the colors
@Nicolas Tremblay yeah, my understanding is that some of the "special sauce" in the commercial units is the software that helps determine when it sees a peak, since color does affect the absolute amount returned. but in theory with a good spectrometer and some intelligent thresholding you can work around it. Nanovea and the other companies claim it works on all colors and reflective so there's _some_ way to do it
@Hexastorm that's neat! Definitely going to have a closer read. I'm noodling over a direct write laser lithography system in the future so this would be good reading for that too :)
Ok, so the error correction is mostly on the software side with a bit of pre-filtering.
I'm surprised you haven't delved into a self hacked SEM.
yeah, that's at least how I've interpreted it based on some papers and noodling over the commercial units marketing material :) but i'm sure the devil is in the details, as I learned with the regular confocal hehe
Random thought. Confocal microscope, using two-photon process for curing photoresists with resolution quite below the diffraction limit.
Read that as *curling*, was confused
if the resist is curling, your adhesion to substrate sucks. :P
@kjansky1 yunno, I keep wanting to (there are some cool papers for mini SEMs using permanent magnets!) but tbh my EE skills are terrible, and HV scares the daylights out of me. Slowly working on learning more because I'd love to, but yeah, the electronics part is my nemesis. Really want to work on a focussed ion beam even more than SEM actually, but same issues
The danger of HV depends more on the deliverable current (and energy). You can get dozens to maybe hundreds kV from static spark. It's the current that kills, the voltage only pushes it through.
And then to be even more specific, if you have a high voltage across your body, you will also have a high current going through it too. V=IR is always always always true.
@polyfractal , have you ever considered laser induced forward transfer? would be curious to see a simple setup
good to know! actually on that note, if anyone has recommendations on HV texts/tutorials/etc I'd be grateful! Sometimes hard to find good learning resources that aren't like "Build a tesla coil!" style resources
Also I just wanted to comment that it's cool you have a bio background before this. I started in biochemistry and the transition to engineering was interesting to say the least.
Depends on how "hard" the power supply is. If it is weak, the voltage quickly drops.
Read somewhere of a hacked SEM with a reworked gun from a old CRT for the beam.
For HV, go look up Plasma Channel. He might help you
@polyfractal how long did it take you to make the laser confocal video (excluding construction) ?
Jay Bowles will host the Hack Chat on Wednesday, September 23, 2020 at noon Pacific Time. Time zones got you down? Here's a handy time converter! Most kids catch on to the fact that matter can exist in three states -- solid, liquid, and gas -- pretty early in life, usually after playing in the snow a few times.
Anybody here knowledgeable about DIC (differential interference contrast), especiallyin the reflected light variant? how does the choics of a DIC prism depend on the lens?
We had Jay on last year!
@Dan Maloney , yup, that was a fun one :P
@Hexastorm yes! I love that you know of the technique, it's super cool. I've tried a few times but haven't had a lot of luck getting "clean" transfer. just molten splatter, or complete vaporization. Part of the issue I think is the laser software -- the literal worst software ever made, EzCAD -- which makes it hard to precisely control the beam. E.g. hard to drop a single pulse where you want it. But I think it should be doable with a bit more tuning, it's pretty trivial to get "large" transfer like copper from one slide to another
Will check out Plasma Channel, thanks!
@Ahron Wayne yay another bio! Yeah I imagine transferring into a real engineering role would be quite a change :) Software was a decent side-move for me since I always did software stuff on the side (originally was a CS major)
@Hexastorm like just the filming/editing part of the video?
I did some experiments with control of a CO2 laser. Notoriously hard to get low power from the tube, the discharge won't light/stay at low currents. but the power supply responds *fast* so the amount of energy delivered can be easily controlled by the pulse time, which is easy to generate with a spare timer on the arduino with just a bit of patch of Marlin.
@polyfractal What project would you recommend for a beginner who wants to dip his toes in diy microscopes?
gotcha. Filming is typically a few hours tops. I like to just let the camera roll and do takes until I'm happy with the delivery, then move on to the next section and repeat. Afterwards grab any b-roll as required. Makes editing longer though since there is like 2 continuous hours of footage to work through. Editing is probably 5-6 hours total, plus thumbnails and all that jazz. but yeah after a project is "done" i can usually get the video part done in a weekend'ish
Uhm... So that's it? Just a bunch of people chatting?
That would be the case if I was ever in a "real" role, still goofing off in an academic setting :) I have considered being in software just because it's so in demand and it's accessible for work. Not sure if my Python skills are good enough for a "real" job though.
@perisackhd I would recommend you start relatively macro, like with a USB microscope or RPI lens flipped backward. Or you can work with an existing project like openflexure.
@Timo afraid I don't know much about how DIC works, only used it as an end-user in lab :(
@polyfractal did you have a "big break" when it came to making videos, or did you have a steady clip of subscribers from the beginning?
@perlsackhd ++ what @Ahron Wayne mentioned. OpenFlexure is a pretty great little ecosystem. Or just hooking a microscope objective up to an RPi camera yourself, the simplest form is just an objective + camera. Make sure to get a non-infinity objective, they are typically around 160mm. meaning the camera just needs to be 160mm away. The infinity lenses are focused to infinity which is great when you need other stuff in the optical stack (like beamsplitters, etc) but complicates things since you'll need another lens to focus it onto the camera
@Birk -- that's why we call it a "Hack Chat"
Open flexure seems like a great start to get into "optical" microscopy
Feel free to join in with questions, though
How about something like this: Fiber-optic confocal microscope using a MEMS scanner and miniature objective lens
HJ Shin, MC Pierce, D Lee, H Ra, O Solgaard… - Optics …, 2007 - osapublishing.org
@Ahron Wayne definitely had a "big break" moment. I was slowly accumulating subscribers up until about 5-6k, then the YT algo decided to push a ton of traffic to my high speed chatter video and that really blew up the subscriber count. Ben Krasnow also noticed the copper deposition video and tweeted, which brough in a lot of cool folks :)
@perlsackhd and not to gotcha @polyfractal but if it's non-infinity, it doesn't have to be *exactly* that distance away (something I worried about when I got into macro). If the lens is closer to your sensor the image will just be less magnified.
@polyfractal I indeed first saw you through your high speed chatter video. 5-6k is still really great to me too.
Cough cough, Hackaday ;-)
that's actually one thing i like (and sometimes curse) about optics, there's a lot of manual fiddling/tuning you can do to get things working. and it's relatively accessible since you can stick a piece of paper in between lenses to see what's going on
When you're operating a machine that's powerful enough to tear a solid metal block to shards, it pays to be attentive to details. The angular momentum of the spindle of a modern CNC machine can be trouble if it gets unleashed the wrong way, which is why generations of machinists have developed an ear for the telltale sign of impending doom: chatter.
:) <3 HaD
Think that was the first time I had seen one of your vids, actually, so it probably was that mysterious YT algo push.
and yeah, I was pleased as punch at 5-6k! didnt know what to do with myself when it like tripled in a week :)
the YT algo gods move in mysterious ways
@polyfractal I too saw the chattering video first then long time nothing and after seeing the LSM video remembered the Chattering video
What is a video that you worked really hard on, or just otherwise wish got a lot more attention?
@kjansky1 just had a quick skim, that looks really neat! only downside is that fiber stuff can sometimes be expensive, but it does remove a lot of the alignment issues too which is great, and the fiber itself acts as the pinhole, etc etc
i need help plss
@Ahron Wayne hmmmm, good question. I have a soft spot for a video about hollow microlattices, sorta based on a Science paper, which for various reasons didn't do super well (at the beginning of my transition to material science topics, too much faffing around in the beginning, etc). but I thought it was a neat topic :)
More recently I did a video about sputter shadow masks, but included a Blade Runner trailer spoof and was too cutsey with the title/thumbnail which really penalized traffic. oh well :)