A large part of my research at Columbia has consisted of designing and building scanning tunneling microscopes. Click the images below for some details on the engineering aspects of this work.
Custom Low Temperature Microscope: In the summer of 2011, we began constructing a custom-designed, low temperature STM. We assembled the machine, tested, extensively debugged, and now take data on it full time. This process spanned the gamut of engineering from the physical task of moving and assembling heavy equipment, to thermal radiation and conductance analysis, to ex situ diagnosis of electrical and mechanical issues.
The microscope has an extremely low Helium boil-off rate of 1.25 liters/day and can maintain multi-day, millikelvin thermal stability over a wide temperature range of 5-80K. Click on the image to the right to see some pictures of the assembly process.
Piezoelectric Linear Actuator: I designed and machined by hand a piezoelectric-driven, titanium actuator with a 1/2" range and sub-nanometer positioning resolution. The device is used for coarse positioning of the STM tip relative to the sample. Consequently, the actuator must be able to operate at extremely low temperatures(T~4 K), and the materials must be suitable for ultra high vacuum (P~10^-11 Torr). The device must also be compact - the cylinder that surrounds the device is 0.86" in diameter and 2" long.
The process of building the device involved designing parts and assemblies in SolidWorks, machining titanium on a mill and lathe, gluing and soldering piezoelectric actuators, and building a high vacuum testing apparatus for low temperature performance analysis. Click the image to the right for pictures of the building process. Check out the applet below to rotate and view a 3D model of the part.
To come soon