Development of a Low-Cost Electron Microscope for Educational Purposes

Electron microscopy is a powerful tool for exploring microscopic world, yet its high cost and operational complexity severely limit accessibility, particularly within educational institutions. Commercial systems are often designed as opaque "black boxes," further hindering hands-on learning and experimentation. This dissertation introduces the Educational Scanning/Transmission Electron Microscope (EduSEM), a project designed to overcome these barriers by developing a low-cost, modular, and transparent electron microscope optimized for educational use. The EduSEM achieves significant cost reduction by operating in a rough vacuum environment (1-20 mTorr), eliminating the need for expensive high-vacuum pumps. This necessitates novel component designs tolerant of higher pressures. The primary contributions include a durable Radio Frequency Inductively Coupled Plasma (RF ICP) electron source capable of stable operation and electron extraction (up to 100 µA demonstrated) in rough vacuum; an innovative, high-gain backscatter electron detector utilizing a GAGG:Ce scintillator coupled to a Silicon Photomultiplier (SiPM), offering cost-effective performance without requiring high voltage biasing within the chamber; and a highly modular architecture for both the physical column, allowing components to be easily reconfigured and stacked for different operational modes, and the modular electronics system. The electronics framework employs standardized, wirelessly controlled modules based on the RP2040 microcontroller and MicroPython, featuring a remote interface system that simplifies development, reduces cabling complexity, enhances noise immunity, and promotes component reusability for broader instrumentation applications. The design, construction, and testing of the EduSEM system and its core components are presented. Preliminary results demonstrate successful TEM imaging capabilities, initial characterization of the RF ICP source plasma properties and beam behavior, and validation of the backscatter detector performance compared to commercial detectors. The modular electronics framework has been successfully implemented across various subsystems, including lens current drivers, RF generation and measurement, beam deflection amplifiers, scan control, detector interfaces, high-voltage power supply control, and Langmuir probe instrumentation. The EduSEM project demonstrates a viable approach to creating affordable, accessible, and educationally valuable electron microscopes. By prioritizing modularity, transparency, and robust operation in less-ideal conditions, it provides a platform that not only facilitates microscale imaging but also fosters deeper engagement with instrument design, systems thinking, and experimental physics.