A Scanning Electron Microscope for the Living Room

There are hackers who have soldering setups on the dining room table, and then there are hackers who have scanning electron microscopes in their living room. [Macona] is part of the latter group, with a Hitachi S-450 SEM he’s repaired and modified himself. [Macona] has documented the whole thing on Hackaday.io. The Hitachi came to him and a friend as a derelict. First it was broken, then stored for 10 years. It turned out the problem was a high voltage cable cut and spliced with electrical tape. The tape eventually broke down and shorted out the 500V supply. Thankfully the rectifier diodes were the only parts that needed to be replaced.

analog1The SEM sprang to life and gave [Macona] and a friend their first images. However, SEMs are finicky beasts. Eventually the filament burned out and needed to be replaced. New filaments are $500 US for a box of 10, which is more than [Macona] wanted to spend. It turns out filaments can be built at home. A bit of .089mm tungsten wire and a spot welder were all it took to fix the issue. Next to go bad was the scan amplifier. While SEMs use many exotic parts, the Hitachi used relatively common Sanyo STK070 audio amplifiers for the purpose – an easy fix!

One thing that makes this SEM unique is the is Energy Dispersive X-Ray Spectroscopy (EDX) unit attached to it. The fragile liquid nitrogen cooled sensor was working, but the 1980’s era signal processing computer was a bit too old to bring up. A friend and fellow SEM hobbiest gave [Macona] a slightly newer Kevex Sigma Gold signal processor, which was nearly a plug and play upgrade for his machine. The new processor processor also gave him digital beam controls and a digital output which could be used to capture images with a PC.

Once all the connections were made, the EDX worked surprisingly well, even finding gold in a uranium ore sample placed in the microscope.

Now that old scanning electron microscopes being retired, it’s only a matter of time before more us get a chance to join the ranks of [Jeri Ellsworth], [Ben Krasnow] and [Macona] with our own personal SEMs!

[Ben Krasnow] Hacks a Scanning Electron Microscope

[Ben Krasnow] is quite possibly the only hacker with a Scanning Electron Microscope (SEM) collection. He’s acquired a JEOL JSM-T200, which was hot stuff back in the early 1980’s. [Ben] got a great deal, too.  He only had to pay shipping from Sweden to his garage. The SEM was actually dropped during shipment, but thankfully the only damage was a loose CRT neck plug. The JSM-T200 joins [Ben’s] homemade SEM, his DIY CT scanner, the perfect cookie machine, and a host of other projects in his lab.

The JSM-T200 is old tech; the primary way to store an image from this machine is through a screen-mounted Polaroid camera, much like an old oscilloscope. However, it still has a lot in common with current SEMs. In live video modes, an SEM can only collect one or two reflected electrons off a given section of a target. This creates a low contrast ghostly image we’ve come to associate with SEMs.

Attempting to fire more electrons at the target will de-focus the beam due to the electrons repelling each other. Trying to fire the electrons from higher voltages will just embed them into the target. Even SEMs with newer technology have to contend with these issues. Luckily, there is a way around them.

When “writing to photo”, the microscope switches to a slow scan mode, where the image is scanned over a period of a minute. This slower scan gives the microscope extra time to fire and collect more electrons – leading to a much better image. Using this mode, [Ben] discovered his microscope was capable of producing high-resolution digital images. It just needed a digital acquisition subsystem grafted on.

Click past the break to see how [Ben] modernized his microscope!

Continue reading “[Ben Krasnow] Hacks a Scanning Electron Microscope”

Hackaday Links: June 15, 2014

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Love the classic brick Game Boy, but hate the low-contrast LCD, terrible battery life, and the inability to play Pokemon Emerald? This one’s just for you. It’s the ultimate DMG Game Boy – a Game Boy Advance SP stuffed (is it stuffed if it’s taking up more room?) into the classic Game Boy enclosure. Forum thread.

Zooming in to a microchip. It starts off with a DSLR and ends up on a scanning electron microscope. This is an older chip, and the CPU you’re using right now probably has much smaller features.

Every movie and every TV show set in space invariably has space helmets with LEDs pointing towards the face. Think how annoying that would be for an astronaut. Here’s how you add LEDs to a space helmet for a nice theatrical effect. Just don’t use it on a real EVA.

Everyone’s favorite crowdfunded space probe can apparently be detected with an 8-foot dish. That’s the same size as an old C-band dish, a.k.a West Virginia wildflowers. We know some of you have one of these out there, so go make a ~2GHz feed horn, grab a USB TV dongle, write it up, and send it in.

Alright, MAME cabinets. Say you want to go old-school and have a CRT. Some arcade games use a vertically oriented display, while other, slightly more modern games use a horizontally mounted display. How do you fix this? Get a big bearing, of course. This one allows a 19″ CRT to be rotated 90 degrees – all you need, really, if you’re switching between Pacman and Mortal Kombat.

Hey mechanical keyboard enthusiasts! Here’s some Hackaday Cherry MX keycaps. Informal interest check in the comments below. Suggestions welcome.

Electron Beam Control In A Scanning Electron Microscope

Electron

A few years ago [Ben Krasnow] built a scanning electron microscope from a few parts he had sitting around. He’s done a few overviews of how he built his SEM, but now he’s put up a great video on how to control electrons, focus them into a point, and scan a sample.

The basic idea behind a scanning electron microscope is to shoot electrons down a tube, focus them into a point, and scan a conductive sample and detect the secondary electrons shot off the sample and display them on an oscilloscope. [Ben] is generating electrons with a small tungsten filament at the top of his electron ‘stack’. Being like charged, these electrons naturally fan out, so a good bit of electron optics are required to get a small point.

Focusing is done through a series of pinholes and electrostatic deflectors, much like you’d see in an old oscilloscope CRT. In the video, you can see [Ben] shooting electrons and displaying a Christmas tree graphic  onto a piece of phosphor-coated glass. He has a pretty big scanning area in his SEM, more than enough to look at a few chips, wafers, and whatever other crazy stuff is coming out of [Ben]’s lab.

Video below, along with the three-year-old overview of the entire microscope.

Continue reading “Electron Beam Control In A Scanning Electron Microscope”

10 µm Scanning electron microscope from Vidicon tube

[Segelfam] built his own scanning electron microscope. He based the machine around an old Vidicon tube, a video recording technology that was used in NASA’s unmanned space probes prior the Galileo probe in the late 1970’s. We struggle a bit with the machine translation of [Segelfam’s] original build log, but it seems that he filled the tube with helium in order to convert it for use as a microscope. But don’t worry, if you’re interested in this hack the information is all there – between the forum thread and build log – it’s just a matter of putting it all together to fill in the details.

In case you were wondering, the image to the upper right has been colored using Photoshop; the rest are straight from the SEM.

[Thanks Jerry]