Faculty Sponsor's Department:
Transmission electron microscopes (TEMs) use an electron beam to create high resolution, 2-D images on the Nanospace scale. Electron microscope (EM) lenses create an electromagnetic field by passing current through a coil, focusing the electron rays and directing the magnetic field. The lens pole pieces perform the final shaping of the magnetic field lines and contribute significantly to the quality of the images produced. To optimize this performance for differing applications, pole pieces are available in a variety of sizes and types. Reducing the size of the pole piece gap improves the resolution of the image but restricts sample-tilt range and x-ray spectroscopy collection efficiency. Expanding this gap has the opposite effect. The desired outcome for any given experiment is based on the sample type and purpose of the investigation. Unfortunately, pole-pieces are installed during manufacture and are not changeable once the instrument is in service. In this project, we seek to achieve two main goals. The first goal is to scrutinise existing pole-piece parameters dictating its performance (such as pole-gap, bore, construction material and signal escape angles). The second goal is to explore routes to develop an adjustable design which can respond to the needs of the individual experiment. Solidworks and COMSOL were used as platforms to design and evaluate our prototypes’ structural mechanism and electromagnetic properties. A recreation of the current pole piece in Solidworks and a magnetic field simulation in COMSOL were used to establish a reference design as well as a benchmark for the shape and strength of the magnetic field. We subsequently developed a method to adjust the pole piece gap before performing COMSOL electromagnetic simulations and preparing for a 3D printed prototype.