No matter how fine your fine motor skills may be, it’s really hard to manipulate anything on the stage of a microscope with any kind of accuracy. One jitter or caffeine-induced tremor means the feature of interest on the sample you’re looking at shoots off out of the field of view, and getting back to where you were is a tedious matter of trial and error.
Mechanical help on the microscope stage is nice, and electromechanical help is even better, but a DIY fully motorized microscope stage with complete motion control is the way to go for the serious microscopist on a budget. Granted, not too many people are in [fabiorinaldus]’ position of having a swell microscope like the Olympus IX50, and those that do probably work for an outfit that can afford all the bells and whistles. But this home-brew stage ticks off all the boxes on design and execution. The slide is moved across the stage in two dimensions with small NEMA-8 steppers and microstepping controllers connected to two linear drives that are almost completely 3D-printed. The final resolution on the drives is an insane 0.000027344 mm. An Arduino lives in the custom-built control box and a control pad with joystick, buttons, and an OLED display allow the stage to return to set positions of interest. It’s really quite a build.
It might seem like a paradox that you want a dark field to see things with an expensive microscope. As [IMSAI Guy] explains, a dark field microscope doesn’t make the subject dark. It makes the area surrounding the subject dark. After selling his expensive microscope, he found he missed having the capability, so he decided to make one cheaply. You can see how he did it in the video, below.
Dark field microscopy gives better contrast and resolution by discarding light that shines directly through or reflects directly from a sample. The only light you see is any that scatters. If you think about a normal microscope, you can imagine a cone of light coming from the top or the bottom. The tip of the cone hits the sample and then spreads back out into another cone of light. What hits your eye –well, actually, the eyepiece — is all the light from that cone. In a dark field instrument, the illumination cone is hollow — the light is just a ring. That means any light the sample doesn’t scatter gets blocked by a stop in the objective. When there is no sample, there’s no unblocked light, so you see a “dark field.”
Light that either refracts through the sample (from below) or bounces off a feature (from the top) will wind up in the hollow area that passes through the objective and you’ll see the image. It may surprise you that you may already have a piece of dark field technology on your desk. Optical computer mice that can work on glass surfaces use this same technique. If you want to see some examples and a diagram of how it all works, we did a post on a similar lower tech mod. There’s also Wikipedia.
The secret to doing this cheaply was to get a used dark field objective with a little rust on the barrel and then modify them with a custom PC board to create an LED ring light. This is different from the usual illuminator which shines a light through a patch stop to block the inner light. In this case, the light is made into a ring shape by virtue of the arrangement of the LEDs.
Most of us have heard some form of the adage, “You can buy cheaper, but you’ll never pay less.” It means that cheaper products ultimately do not stand up to the needs of their superior counterparts. Hackers love to prove this aphorism wrong by applying inexpensive upgrades to inexpensive tools to fill up a feature-rich tool bag. Take [The Thought Emporium] who has upgraded an entry-level microscope into one capable of polarized and dark-field microscopy. You can also see the video after the break.
Functionally, polarized images can reveal hidden features of things like striations in crystals or stress lines in hot glue threads. Dark-field microscopy is like replacing the normally glaring white background with a black background, and we here at Hackaday approve of that décor choice. Polarizing filters sheets are not expensive and installation can be quick, depending on your scope. Adding a dark-field filter could cost as much as a dime.
Like most mods, the greatest investment will be your time. That investment will pay back immediately by familiarizing you with your tools and their workings. In the long-run, you will have a tool with greater power.
Sometimes, less is more. Sometimes, more is more. There is a type of person who believes that if enough photos of the same subject are taken, one of them will shine above the rest as a gleaming example of what is possible with a phone camera and a steady hand. Other people know how to frame a picture before hitting the shutter button. In some cases, the best method may be snapping a handful of photos to get one good one, not by chance, but by design.
[The Thought Emporium]’s video, also below the break, is about getting crisp pictures from a DSLR camera and a microscope using focus stacking, sometimes called image stacking. The premise is to take a series of photos that each have a different part of the subject in focus. In a microscope, this range will be microscopic but in a park, that could be several meters. When the images are combined, he uses Adobe products, the areas in focus are saved while the out-of-focus areas are discarded and the result is a single photo with an impossible depth of focus. We can’t help but remember those light-field cameras which didn’t rely on moving lenses to focus but took many photos, each at a different focal range.
With the fine work needed for surface-mount technology, most of the job entails overcoming the limits of the human body. Eyes more than a couple of decades old need help to see what’s going on, and fingers that are fine for manipulating relatively large objects need mechanical assistance to grasp tiny SMT components. But where it can really fall apart is when you get the shakes, those involuntary tiny muscle movements that we rarely notice in the real world, but wreak havoc as we try to place components on a PCB.
To fight the shakes, you can do one of two things: remove the human, or improve the human. Unable to justify a pick and place robot for the former, [Tom] opted to build a quick hand support for surface-mount work, and the results are impressive considering it’s built entirely of scrap. It’s just a three-piece arm with standard butt hinges for joints; mounted so the hinge pins are perpendicular to the work surface and fitted with a horizontal hand rest, it constrains movement to a plane above the PCB. A hole in the hand rest for a small vacuum tip allows [Tom] to pick up a part and place it on the board — he reports that the tackiness of the solder paste is enough to remove the SMD from the tip. The video below shows it in action with decent results, but we wonder if an acrylic hand rest might provide better visibility.
Not ready for your own pick and place? That’s understandable; not every shop needs that scale of production. But we think this is a great idea for making SMT approachable to a wider audience.
While it’s true that we didn’t specifically say making Hackaday staff exceedingly jealous of your good fortune would deduct points from your entry into our ongoing “Repairs You Can Print Contest”, we feel like [Sam Perry] really should have known better. During a recent dumpster dive he found an older, slightly damaged, but still ridiculously awesome Mantis stereo inspection microscope. Seriously, who’s throwing stuff like this away?
Apparently, the microscope itself worked fine, and beyond some scratches and dings that accumulated over the years, the only serious issue was a completely shattered mount. Luckily he still had the pieces and could get a pretty good idea of what it was supposed to look like. After what we imagine was not an insignificant amount of time in Fusion 360, he was able to model and then print a replacement.
The replacement part was printed on a Tronxy P802M in PLA. Even at 0.3mm layer height, it still took over 10 hours to print such a large and complex component. A few standard nuts and bolts later, and he had a drop-in replacement for the original mount.
Whether it’s due to how big and heavy the Mantis is, or a slight miscalculation in his model, [Sam] does mention that the scope doesn’t sit perfectly level; he estimates it’s off by about 5 degrees.
We’re somewhat suspicious that mentioning an error of only 5 degrees is a stealth-brag on the same level as telling everyone you found a Mantis in the trash. But if [Sam] gives us the GPS coordinates of the dumpster in which people are throwing away high-end lab equipment, all will be forgiven.
There’s still plenty of time to get your entry into the “Repairs You Can Print” contest! The top twenty projects will receive $100 in Tindie store credit, and the top entries in the Student and Organization categories will each receive a Prusa i3 MK3 with the Quad Material upgrade kit: arguably one of the best 3D printers currently on the market. If you were considering going back to school, or finally leaving your basement and joining a hackerspace, now would definitely be the time.
[Amen] obtained a microscope whose light source was an incandescent bulb, but the light from it seemed awfully dim even at its brightest setting. Rather than hunt down a replacement, he decided to replace the bulb with a 1W LED mounted on a metal cylinder. The retrofit was successful, but there were numerous constraints on his work that complicated things. The original bulb and the LED replacement differed not just in shape and size, but also in electrical requirements. The bulb was also part of an assembly that used a two-pronged plug off to the side for power. In the end, [Amen] used 3D printing, a bit of metal work, and a bridge rectifier on some stripboard to successfully replace his microscope’s incandescent bulb assembly with an LED. He even used a lathe to make connector pins that mated properly with the microscope’s proprietary power connector, so that the LED unit could be a drop-in module.
Working on existing equipment always puts constraints on one’s work, usually due to space limitations, but sometimes also proprietary signals. For example, a common issue when refitting a projector with an LED is to discover that the projector expects a stock bulb, and refuses to boot up without one. Happily, the microscope didn’t care much about the bulb itself, and with the LED positioned in roughly the same position as the original bulb’s filament [Amen] obtained smooth and even lighting across the field of view with no changes made to the microscope itself.
By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more