DVD Optics Power This Scanning Laser Microscope

We’ve all likely seen the amazing images possible with a scanning electron microscope. An SEM can yield remarkably detailed 3D images of the tiniest structures, and they can be invaluable tools for research. But blasting high-energy cathode rays onto metal-coated samples in the vacuum chamber of a bulky and expensive instrument isn’t the only way to make useful images, as this home-brew laser scanning microscope demonstrates.

This one comes to us by way of [GaudiLabs], a Swiss outfit devoted to open-source lab equipment that enables citizen science; we saw their pocket-sized thermal cycler for PCR a while back. The basic scheme here is known as confocal laser scanning fluorescence microscopy, where a laser at one wavelength excites fluorescent tags bound to structures in a sample. Light emitted by the tags is collected, and a 3D image is built up from multiple scans of the sample at different focal planes.

Like many DIY projects, this microscope is built from old DVD parts, specifically the pickup heads. The precision optics in these commonly available assemblies, which are good enough to read pits as small as 150 nm on a Blu-Ray DVD, are well-suited for resolving similarly sized microstructures. One DVD pickup is used to scan the laser in the X-axis, while the other head is modified to carry the sample and move it in the Y-axis. The pickup head coils and laser are driven by an Arduino carried on a custom PCB along with the DVD heads. Complete build files are posted on GitHub for anyone interested in recreating this work.

We love tips like this that dig back a bit and find things we missed the first go-around. And the equipment [GaudiLabs] lists really has potential for the budding biohacker, which we also like.

Thanks for the tip on this one, [Bill].

35 thoughts on “DVD Optics Power This Scanning Laser Microscope

      1. Wrong, as the spot size is 250nm. Which is compensated by gaps between the tracks. Just because you get a signal from a 150nm pit doesn’t mean the laser itself focuses this narrow.

  1. Moral of the story seems to be that scientific equipment doesn’t have any reason besides small scale to be expensive, and we could all have our own microscopes and GS-MS and things like if someone would fund it!

    How many polluted things go unnoticed every day? This kind of tech could really benefit the world if it becomes widely available.

    1. When I was a kid, I would have loved to have something like this. Back then there were only crappy microscopes which wouldn’t even show a single plant cell. It completely killed my interest in biology. Also hated that you could only look trough a small hole and there weren’t anything that you could connect to a computer or even TV back in the days.

      Thankfully I found a bunch of random chemicals from the schools attic and had very much fun with them. Electricity was also very fun as a child. :D And possible to experiment with. That’s what increased my interest in it.

      1. “Back then there were only crappy microscopes which wouldn’t even show a single plant cell.”

        Hmmm, toy manufacturers should be held accountable for what they’re allowed to call microscopes and telescopes, etc. There always has been some around that are 100% trash, landfill bait on the shelf. But there always has been some around that were at least useful at their medium power. (The good ones still get caught up by the marketing departments desire to have the biggest number 2000x magnification!!! even if it’s completely useless.) I myself had a unit that was my uncles when he was a kid, and that was on a par with the equipment in the school labs. I have also bought a couple of “kids” microscopes over the years that are functional enough for basic duties.

        1. I bought a microscope kit from LIDL a few years ago, it was around 30 EUR, it even has a crappy USB webcam. The optics are not great but certainly good enough to resolve cells. It also has switchable top and bottom illumination and an XY stage.
          Just writing this in case somebody stumbles upon some old microscope from the 40s on ebay and thinks it’s a good deal.

      2. I had one of those crappy Gilbert microscope sets when I was a kid. There was no way my folks could have afforded anything better. It was one of the best Christmas gifts I ever got. Yes, it was crude and the images not so sharp, but I spent many pleasant hours using it.

    2. “Moral of the story seems to be that scientific equipment doesn’t have any reason besides small scale to be expensive, and we could all have our own microscopes and GS-MS and things like if someone would fund it!”

      I imagine science requires things like precision, accuracy, and repeatability. What good is science if everyone gets different results?

      1. If using a different microscope than someone else gives you different results, maybe your results are more dependent on the microscope than science. Back to the hypothesis!

      2. “I imagine science requires things like precision, accuracy, and repeatability. What good is science if everyone gets different results?”

        Right on, at the imagination station. For the quantitative methods, you’ll want to add the linearity, limit of detection/quantification, range, maybe robustness/ruggedness.

        For the Identification methods you forgot to include the “specificity.” Definitely want to be specific first and foremost, no alpha or beta error is acceptable.

        Here’s an example… though seems confusing to me as written and I don’t recall the actually USP/NF or EP I used being so… take with a grain of salt (KCl if you have high blood pressure I guess). http://www.uspbpep.com/usp29/v29240/usp29nf24s0_c1225.html

    3. Limited production scale, complexity, tooling costs, support costs, and SOFTWARE. We forget that after you produce a signal with hardware, it has to be collected with sufficient signal resolution and no dropped bits, in sync with the physical reality, and then processed by software, which requires continuing support. We have an instrument that was purchased at the end of the last decade that charged (at that time) $1000 per seat. Every version upgrade cost more money, but the hardware was robust enough (and taken care of well enough) that it still runs. The manufacturer declared it obsolete at least 5 years ago, the software is hardware locked with a parallel port dongle, and we have to maintain a machine running Win 7 just to keep it functional. Replacement cost: more than $100K. So we keep it running. Having seen a newer version of the machine, they put their development dollars in hardware and electronics, because the software features are nearly the same, and still cost beaucoup bucks per seat for the software.

  2. I always think it’s funny, when monochrome images are colored green, as if we were looking at a P1 phosphor screen. Especially when so few of us have even SEEN a P1 phosphor screen with our own eyes.

    But the project is great! A true hack, that couldn’t have been done with a 555.

    1. I have looked into a few monochrome green screens in the early-mid 1980ies. Text terminals or an Apple ][e with green monitor. But I do not know if this were P1 phosphor screens My old analog scope has a different hue of green, more turquoise.

      1. P1 was the standard oscilloscope phosphor from the dawn of time until the mid-60s, when P31, the more turquoise one became standard because of its higher brightness. This happened around the same time that oscilloscope CRTs became rectangular. So naturally most green terminals and monitors used P1. It’s not like it was a well-defined standard, though – everybody had their secret recipe, so DuMont’s P1 was different from General Atronics’. I wasn’t thinking about computer monitors, so there are plenty more people who’ve gazed upon P1’s greenness than I pictured.

    2. Of course it could be done with a few 555’s(x and Y ramp generators), a lot of trimmers to replace auto-focus and all the nifty arduino-enabled extra features.
      And an oscilloscope in XYz mode for display.
      Would I do it like that… no, but it could definitely be done.

    3. I looked at those photos last night while my phone was on b&w mode, then again this morning while it was in color mode. I found it MUCH easier to see details with the green coloring.

      1. The Apple Laptop CD/DVD drives have really smooth tight sleds also that I think if Lord helps me… I can finally make some variable collimators with the two I’ve disassembled down to what I’m thinking will be only what’s required to control the motor with an MCU. They have a nice hole for the pvc/aluminum tubes I have also.

        Thinking to sweep using an HD-DVD or BluRay disc diffraction grating, will use a HD actuator. I guess I get buffoons with all my stuff as soon as I go to play right.

  3. If anyone is interested there’s a thread dedicated to optical pickup hacking (started by this guy) over at the hackteria forum: https://forum.hackteria.org/t/laser-optical-pickup-unit-hacking/771

    There’s just so much you can do with these optical disk drives and I hope that I can get my own project with the KES-400a pickup unit (from the “fat” playstation 3) to do proper laser scanning too. Not just because I went crazy and bought 100 of them, but because they’re uniquely suited to hacking: Cheap, robust, and with swappable components serviced by screw holes and proper ribbon cables.

  4. I wish there was a dedicated article or resource for getting started with fluorescence microscopy and color filters. Maybe I did not spend enough time looking but I haven’t been able to find such a thing for dummies: what accesible media to use, what cheap (or homemade) contrast substances, what color filters.

  5. It reminds me of a doco I saw about 10 years back where they were able to use a standard cd/dvd drive to detect some pathogens in a sample. I can’t remember what the program was and they didn’t give much details on how it was done but it was cool nontheless.

    1. I don’t know for sure how this was done either, but I saw (and reproduced) a demo that may hint at how to do it: It is a true fact (I’ve done this myself, as I said), that you can drill a 6mm hole in a CD, and it will play without missing anything, as long as the disc is otherwise undamaged. So at least in principle, one could mill down through the aluminum layer into the polycarbonate, place a sample in the cavity, and cover it with a transparent chip if necessary. Then tap into the signal coming from the laser sensor, and play that song on the CD, digitizing and capturing the raw data. It shouldn’t be too hard to separate the CD data from the microscope sample.

  6. I’m surprised nothing is really mentioned in the article about the safety aspect. Granted the target audience is most likely towards someone that has already had the needed training with laser safety there should be a mention of safety for the people who do not have this training.

    Diode lasers on many commercial devices are potentially dangerous though they can be cannibalized for useful things most of the price involved in lab equipment is usually related to safety for these things. Some laser diodes in addition to emitting the collimated light at the target wavelength also emit NIR wavelengths (invisible) which are quite dangerous.

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