DIY Scanning Electron Microscope - Sources, Costs and References

Metal aluminum window screen

Just a few linearity problems ;)

I used an oscilloscope's X and Y amplifiers for these images. It has much better linearity than my own, but not enough differential voltage or offset range.


The sum total of the big-ticket items shown in the video is $1485. This does not include hoses, wiring, raw metal, teflon, screws, a cabinet, etc. It also does not include an oscilloscope, which can be a very simple model (under $100 on eBay) as long as it has a z axis (brightness) input. Your diffusion pump or diffusion pump baffle may also require a water chiller.

Here are a list of information sources that helped me with this project:

Teralab - Homebuilt electron gun and other great projects
http://www.teralab.co.uk/Experiments/Electron_Optics/Electron_Optics_Page1.htm


Popular Mechanics video on commercial desktop SEM
http://www.popularmechanics.com/technology/gadgets/4218957


Hamamatsu - Supplier of PMTs
http://sales.hamamatsu.com/assets/applications/ETD/pmt_handbook_complete.pdf


TV to oscilloscope circuit
http://www.electronixandmore.com/project/14.html


CRT oscilloscope clock circuit
http://web.jfet.org/vclk/


Charged particle optics simulation program
http://www.electronoptics.com/

"A Simple Scanning Electron Microscope" P.J. Spreadbury -- Advances in Imaging and Electron Physics Vol 133 Chapter 2.5 (no link).


ISI SEM refurb at home
http://members.tm.net/lapointe2/Scanning_Electron_Microscope.html


Great technical info on cathodes and wehnelt cup spacing. Most of the article concerns LaB6 cathodes, but there is a short paragraph on tungsten cathodes.
https://www.kimballphysics.com/cathode/support_PDF/Cathode_ES423_LaB6_info.pdf

Numerous websites that gave background and operational information about SEMs.
Lots of web searches



Nearly all raw materials for this project were purchased from McMaster-Carr. All power supplies were purchased on eBay, or I already had them, in which case they came from a surplus store or flea market. Nearly all of the electronic components came from Jameco.

DIY scanning electron microscope - Overview video

Today, I finally produced an image with my DIY scanning electron microscope. I've spent the last few months working on this project, and am encouraged by today's success. There is still a lot of work left to do in making the image higher resolution, and eliminating sources of noise, however this image proves that all parts of the microscope are operating as designed.

First photos of DIY scanning electron microscope

I'll soon upload a video and full description of this project.

555 Timer Contest Entry

This blog post will show my entry for the 555 timer circuit design contest at http://www.555contest.com


This is a motor speed control circuit that allows safe and easy control of 115VAC "universal motors" like drill motors, blender motors, other power tools, etc.

The motor is controlled directly by a triac-diac component that is found in variable-speed universal motor devices (such as electric drills.) The component will not allow current to flow through the motor until the R-C network charges to a certain level. In this case the capacitance is fixed, but the resistance is determined by a CdS photoresistor. A standard LED is optically coupled to the CdS photoresistor, and the LED is controlled by a 555 astable circuit. The duty cycle of the 555 output waveform will determine the average amount of light falling on the CdS photoresistor, and thus the CdS resistance, and thus the current flowing through the motor. For best operation, the 555 output frequency should be much higher than the mains AC frequency (ie 60 Hz). A good value for the 555 frequency would be about 5 KHz.

The 555 control voltage is set by an opamp circuit (LM324) that amplifies the difference between a user-set voltage and a voltage generated by a small motor whose shaft is coupled to the main motor being controlled. The small motor's function is to generate a DC voltage that is proportional to shaft speed. Its value is amplified and integrated by the opamp circuit for programmatic proportional and integral control.

The 555 serves as a high-current pulse driver for the LED, taking an analog control signal and allowing some control of the pulse rate and height via the R-C timing network and current-limiting resistor.

How to build an air muscle and use it in a force-feedback joystick

In this video, I describe how to build an air muscle, and use it to create a force-feedback joystick




Link to the instructables article (not written by me): http://www.instructables.com/id/How-to-make-air-muscles!/

Silicone tubing - McMaster 51135K281
Braided wire loom (polyester) - McMaster 9284K413