DIY Scanning Laser Microscope 

Dude your videos look soooo good. Also, sweet microscope :)

I have absolutely zero need for a "confocal laser microscope" but your channel is so incredibly well done I can't help but watch.

What's this, I see laser but nothing getting burnt, evaporated or even slightly charred? 🤨 JK that's really cool and I am looking forward to that thing back there in the summer!

Very cool. In the 1990s I worked with a startup developing a commercial confocal laser review station in the semiconductor industry. We scanned the laser in x-y and had a piezo stage for the z-axis. It also required a proprietary frame grabber board that was synced to the laser scanner and z-stage. My work was on the microcontrollers, so I only knew the general optics design. We experienced what we called the pit-particle issue where what we knew to be a solid above the surface (a sub micron calibrated latex sphere) could sometimes show up in the 3D image as a hole.That seems similar to what you were sing on the one image. Our optics engineering team spent a lot of time resolving that, but I don’t recall how they attacked it. Great video. Thanks.

If I may suggest - please consider putting the transimpedance amplifier _very_ close to the photodiode, preferably mount the diode directly piggybacked on the opamp IC (directly soldered, no sockets) onto the DIP8 of the opamp. The capacitance of the long coax between the PD and the TIA limits the bandwidth, in your current setup.

I need (want) one! Awesome work, man!

If you're still working on this, consider replacing your photodiode and aperture with a linear CCD array. You can use the reflected beam width as feedback for the next Z position to find the focal height in 2-3 iterations instead of scanning.

I think one of the reasons why you're getting artifacts is because of how metals reflect light : it's mostly specular reflection(it's directional, in your case parasitic) and not diffusive (unidirectional, what you're detecting). metal oxides, however, tend to build up in tiny crevices of metal surfaces and they are dielectrics, so they create tiny diffusive areas in otherwise specular metal which might look like noisy height changes.

For small movements like, that, maybe a voice-coil based actuator would probably be better - could you maybe adapt a CD/DVD optical block?

Really cool project! Another way to do this is by using a standard cd or dvd laser head. You cannot scan very large areas, but with very high resolution.

After watching this video, I thought this was going to be one of those huge million plus channels that I just hadn't heard of yet. That you only have 25k subs is outrageous to me. Everything here is on par with the best of the best RU-vid has to offer.

You could try to have the beamsplitter at the Brewster angle of you laser source and mirror material, could avoid the laser dump, when the optical path is geometrically redesigned.

Dude your video quality and experimental setups keep on getting better! Awesome stuff, keep it up!

There should be a tech/science youtuber collab, you'd fit in nicely!

Jesus christ! this is a 2Msub channel level production quality! how you manage! I mean, i loved all your videos but you really outdid yourself with this one!

I think the biggest issue is the range of reflectivity. I had this issue with 3d scanning using photogrammetry. Your photos will be greatly affected anywhere there is solder on that PCB, or other curved highly reflective areas. It might be worth trying to air brush a flat color on everything to make the reflective properties uniform, which should normalize your readings and greatly increase the resolution and accuracy of your photos. If air brushing adds too much material to the sample, there might be some gaseous coating options like 2D boron nitride that would only add 1 atom to the height. Good work though. Your channel will do great :)

This is really well done! I watched an OpenFlexure video and this was suggested. Really shows that a lot of time went into the project and into the presentation. Wishing you the best of success.

It's just a matter of time until this channel explodes. Keep on!

Cool project. Try to modulate ur laser beam with chopper or so and demodulate ur photodiode signal at the same frequency. This will remove much of noise.

Hey, I make confocal, whitelight interferometers and microscopes for a living. Here is a few insights to improve your results. 1) Your setup is non-rigid, which means there will be vibrational motion and modes oscillation between sample and microscope. Fix this by adding a heavy base and using steel instead of aluminum. 2) Laser Diodes suffer from Speckle noise, which is up to 15% of intensity. Switch instead to a LED based emitter. 3) Dont leave cables hanging, air drafts might push and move source or detector. Make sure they are fixed. 4) Using thick half mirrors is not recommended, as they create ghosting. That happens when double reflections overlap with slight change in angle. Cheap option is film beam splitter or cube beam splitter. 5)In Confocal, we dont move the stage to scan. Instead, we use DLP (mirror arrays) or liquid crystal to raster the image, pixel by pixel at a fixed height, then move along Z, until we find the peak for all points. Otherwise, its a cool prototype V1. good job.

That project deserves a subscription right out of the box ! Thanks for producing such an interesting content.

Did a fair amount of optics work in university and self-taught myself analog electronics using photo-diode amplifiers. One of my best had a 60fW noise floor, saturated at 20nW, 10Gohm trans-impedance gain, and about 30Hz bandwidth. Very slowly working on a V2, but happy to share V1 in the mean time.

Fascinating. Great job and good explanation of the optical path. I wonder if it would be faster to run the scan like an atomic force microscope, riding the surface by tracking the amplitude of the photodiode. Move a step in x, then move the z up or down to maximize the amplitude, repeat. Advance y each time you hit the end of x. The assumption is the surface is often flat, or at least has a gentle slope, so instead of scanning the whole z stack for an x,y point, just search around the last height (z) each time you move to a neighboring point.

This is amazing! It's fantastic that you can achieve this level of detail using 3d printed components. The explanation was very useful and covers a topic which isn't well covered elsewhere. Thank you.

This channel just keeps getting better!

Very cool, i worked on a similar project a few years back using DVD optical pickup heads and its internal optical path, which is indeed a confocal arrangement with an electromagnetic vertical adjustment which provides a high degree of precision.. my failure was in the X-Y stage.. might have to revisit with openflexure but it was something that worked as an arduino shield.

Hey, awesome video! I see there already was some comments about reflective surfaces here - and that is indeed the probable cause for the inverted shield structure. When the beam hits the slightly higher point of the shields edge it is scattered into the room and not back into the lense making the signal weaker. This would explain the smaller values in some of the curves peaks too. Alexander Sannikov mentioned in their comment that the metal oxides being diffuseve cause noise in the signal. Indeed if the samples were to be prepared beforehand (like they do for electron microscopes) to be compleately matt with a coating of a white matt substance the laser would behave more uniformly along the entire surface.

I love the way you explain! Thank you for shining the light of knowledge all over like that.

Phenomenal video and experiment/build quality. Your presentations have the perfect amount of technical info, and I love hearing about the mistakes/troubleshooting. I hope to see your channel grow and can't wait for your next video.

You've come such a long way in your video production. Hilarious intro and great quality, plus intriguing topics!

This man is absolutely incredible. I wish I was able to retain and use learned information as well as he does. He just is a wealth of knowledge.

Man! your videos are awesome. We get months worth of education in science and technology in every one of them. Your detailed way of explaining is incredible. Thanks

Wow! Really interesting project. Hope to see more of this soon. Thank you for sharing!

2 minutes in, this is what it's all about on so many levels. So impressed already!

This is really impressive! It's great to see people really pushing the limits of DIY science.

Fantastic work with most simple tools. Nice job

Super interesting project! It blends my love of making and metrology. Looking forward to seeing more videos!

Very cool! My knowledge of optical scanning goes no further than end user where I push button and machine goes brrt, so it's great to see the community come together with advice. I'm very excited to see an upgraded model!

YOU GIVE ME HOPE. I'm in awe of this video. My intellect is only barely sufficient to grasp what the components do. It's true that I feel bitter in myself for not being smart enough to do something like this. But I am profoundly happy that you are. It gives me hope for humanity's future that there are people as brilliant as you in the world. It really does. I wish you all the very best

Awesome stuff! I'm amazed that the data collection was actually limiting - I probably would have gone with a different xyz stage and scanned voxels one by one and been way too slow. the continuous scan seemed to be enabled by the latency of the stage so that's pretty awesome! I'm also glad you called out the big cylinder of conflat flanges in the background cause I was getting really curious...

I love the presentation and the work! It was fun to see bits of it in development, and it came out beautifully.

Your channel is *insanely* underrated. This is sooo cool.

I find it absolutely amazing that you built this yourself WOW!! Thanks for sharing

Amazing explanation, I understood the whole process and know why each piece is so important. Great work

The curved surface at the top of the shield is probably scattering light like a convex mirror. If you had a matte textured object you might get better results.

Absolutely love the jank to performance ratio of this project!

Super ambitious project, wow! Very impressed you got any images. Would definitely want better / faster scanning system but it does work so that's amazing.

Great video, 20 minutes fly by, just the right level of detail. From my experience stacking microscope shots and focus failures, it will be that 'specular highlights' (very shiny surfaces) break your algorithm. You'll be assuming that the thing you are scanning has unchanging topology (which is true), but accidentally assuming that when you move the microscope stage that the pattern of light reflected would not change (untrue), because unless the surface is perfectly matte, the 'brightness' does not 1:1 correlate with 'in focus', it also correlates with 'shiny thing pointing at lucky angle to send light back to sender'. Imagine you were scanning a microscopic disco ball, if you strapped a torch to just above a camera lens and moved it closer and further, you'd see that different panels would suddenly become very bright, and others very dark. It confuses normal cameras with their contrast based focus detection (and even sometimes phase detection). If you want to test what I'm talking about, scan some glitter or a retroreflective tape. I would spray the item to be scanned with a misting of 'airplane glue' smelling hairspray in the giant cans from 50cm away. It will 'matte' your surfaces sufficiently. If it kills the retroreflection of tape, it will be scannable by your algorithm.

Love the project, great video, glad it showed up in my feed somehow!

Always enjoy your content!🎬

Holy cow. Hidden gem of a channel. Proud to say I was here before he hits 10 million subs!

awesome intro. loved it. thx for all the work. immediately subscribed.

I cant even tell you how cool this is! Thanks for sharing!

funny video ! It reminded me one of my internship : I had to build an interferometer to mesure optical elements with 10 nm accuracy for the Z dimension. But instead of laser I used a white light source. Thanks for the video, it brought back some great memories :)

Thank you for the video and sharing your journey. Inquisitive as I am about so much, the lessons you share of in these challenges including the good the bad and the ugly enlighten and inspire. Your success is a journey filled with experiences won and lost, always best shared. Thanks again well done.

This looks like an amazing project. Inspiring :)

Wow! That is really amazing! Thanks a lot for sharing! Keep on going!

Wow this is the best channel! BT, great stuff as always! If it doesn't mess with your workflow too much you should consider discussing the upcoming projects at the end of your videos. Also, I'm sure you run into a ton of problems trying to get these types of amazing things working, you should consider asking for help (suggestions and ideas) in the comments. It would help with the RU-vid algorithm, it would get people emotionally invested and it would help you make more videos. Apart from the obvious, I think one of the biggest reasons that AVE and Applied Science have been so successful is that they spend a lot of time fostering genuine discord in the comments. Great videos!

your light setup was so good :)

Omg you are so smart, and I am so in love with this project!

i dont know how you dont have more views and subscribers, this is an awesome project!

This is brilliant. Thanks!

This is legendary! Great job! Now I want to make one.

Wouaw, many thanks the video! This is an amazing work!

this reminds me of how old drum scanners worked, but i cant help but feel there is a better way of measuring depth (and over a much larger area simultaneously) while using a camera sensor and detecting image sharpness.

thank you for sharing this impressive work

I love every single piece of this. Instant sub

Love the project! Miss doing this stuff. Man if it takes a week to image a surface you wonder how much temperature change over that time frame would impact the sample. Its a small area you're sampling but the whole object would chmage temp. For efficiency buildings can drop temp overnight. You're measuring such small features I wonder if it might be enough to cause some of those anomalies in the data plots. It's always a challenge coming up with the right algorithms to filter the way you want but not kill good data or pick the wrong point.

Very cool project, I have got to make one of these!

I audibly shouted "SIIIIICK" when you showed the topological renderings. Instant subscription.

You do some awesome projects! This was very cool!

No words... just 👏...great job

Dude the cinematography in this is NUTS

Really interesting; for pinhole making, you might try an acupuncture needle - sharp and round - works well, and of course various gauges are available.

12:15 you can possibly increase the scanning speed dramatically by making a feedback system, like autofocus, which tracks the surface or, equivalently, the height at which the intensity is maximum, which is the maximum of the curve so when x-y changes, you need only change the z enough to stay at the maximum

Awesome stuff!! The intro hit very close to home :D

This is why I love youtube. Fantastic work.

Excellent work!

I definitely want something like this for measuring tiny inductors and resonant circuitry

Excellent content! Thank you.

i have learned more about building optical set-ups from this video than in all of my 3 years in an electro-optics phd program

This was a great video. I've found having a fiberoptic cable act as the pin hole to be a good solution. Also adding 2 scanning mirror to traverse the XY plane reduces the need to rely on mechanical movement. A photo-multiplier-tube is a great way to increase the electrons per photon ratio. Also using a quarter wave plate and a polarization beam splitter lets you keep more of the precious photons going to the source.

This is really interesting stuff. I just finished my masters on the rotationally coupled imaging of spin coating using a similar optical technology for real-time surface topology observation of the process. If I were to continue I'd definitely integrate some of your mechanics!

I really can't stand how at such exhuming scientific and video quality you only have 25k subscribers. Luckily you have already managed to capture the attention of major scientific channels.

I wouldn't mind seeing you improving upon this. I was able to find a height map of the obverse of a Lincoln cent elsewhere online, and that was an amazing help in creating a model of the bust. If there were some way to get scans of any coin like that, it'd be absolutely amazing.

Quality content here ! Thanks

Absolutely love it!!! (topography btw!)

I dont know if it was already mentioned in the comments, but. I have some experience in 3d scanning, basically extracting height information from a series of images, and the general recommendation for an object not to bee too white, or too black in albedo and what is sometimes more important not to be too shiny. From your samples you can clearely see that varnished surface of a PCB net you the worst result, and edges of the shiny metallic coin tricked sensor into wrong depth, even though the xy shape was correct. Try taking pictures of embossed areas of paper money and see if it will make a real difference. Amazing video though!

Since the system determines depth based on intensity, maybe build a closed loop controller for the laser diode to ensure stability? Also get a bigger laser!

coming from the field of microcopy im impressed at what you were able to make on the basis of these rather simple devices! keep going!

I'm floored. That was awesome. I finally have a project to pursue that will force me to crack the seals of signal processing, python, and optics. Thanks so much!

I had a similar issue with scan time on an IR camera I built, based on a single-point IR detector and a couple of silicon mirrors, also driven by stepper motors. In the end, I got it to a) scan the scene at very low resolution and then b) automatically pick points of interest (essentially, hot bits) and go back and scan around them at higher res.

This is amazing. The intro and its high level editing took the video to places I would have never expected/seen from technical engineering youtube. It was a fresh breath of air. And how you explained the optical parts and what they did made things click that for specifically optics rarely do for me. I have never heard of the 3d printed micromover. You were already a contender for what I consider the absolute top of youtubers (Thought emporium, Tech ingredients, applied science, nighthawkinlight etc). This video cemented it. I am curious if you will vary how you frame/edit your video or continue to expand on what you did in this video. Like If some future videos are similar to you earlier videos or not (I guess it depends on what project youre working on and heavily dependent on what you like at the moment)

Reminds me of Ben Greer’s Single Pixel Camera that used Radon transformations to process the single pixel data.

Nice project. Very good details on what this microscope is and how it works, very good. About the optimization "issue" you commented, I see it as a simple thing to run an arduino (or any other microcontroller) driving the steppers directly and sampling the data. I am not sure how much ADC resolution is required to get nice data, but many uC have 10~12bit ADCs and sample at > 20kS/s, which is way over the stepper frequency. A simple loop will take stepper to "home" and do step; take sample; print sample; next. repeat. You do not need to "verify" the position, just let the actuator (stepper) do it job. There is for sure a time need for the the actuator to stop moving (settle position), but that can be measured by looking at the samples, and dynamically determine how long to wait for. Also running the scan at constant speed, will help to vibration and "inertia problems", ie accelerations. I am not familiar at all with the OpenFlexure device, so maybe I do not see how it would not work like I described.

Amazing video and a super cool idea :D

If you use a ccd sensor without the pinhole, you could scan for the smallest radius, so intensity doesn't matter. that way you can scan both reflectivity and height at the same time, instead of trying to correlate both

Super cool video! I actually deal with laser scanning confocal micros on a daily basis and its super impressive that you were ale to make one on your own, wow :D probably the next, more advanced step for speeding up the scans would be to use piezoelectric mirrors to deviate the laser beam instead of moving the sample. Also motorized lens in Z axis would be awesome to see :)

I bought a used Keyence LT-9500 it uses piezo actuators to move the laser it is an amazing piece of tech available on the used market.

Nice. Seems like it didn't like highly reflective surfaces like the screw and pcb with solder. Great project. The open flexure had come a long way since I first checked it out.