The Open Beam Interface adds digital image acquisition to compatible scanning electron microscopes by capturing detector and scan signals without replacing the microscope’s core systems.
The Open Beam Interface (OBI) is an open-source hardware and software system designed to add digital image acquisition to legacy scanning electron microscopes (SEMs). Instead of replacing the microscope’s electron column, vacuum system, detector, stage or high-voltage electronics, OBI captures existing detector and scan signals and sends them to a computer for image processing.
OBI addresses older microscopes whose imaging hardware has become obsolete even though the main instrument remains functional. The system connects to the detector signal that contains image intensity and the horizontal and vertical scan or timing signals that determine where each sample belongs in the image. The captured data can then be processed by software on a connected computer.
The interface can support digital image capture from SEM, focused ion beam (FIB) and scanning transmission electron microscope (STEM) equipment, while beam control is possible on systems that expose the required interfaces. The project documentation describes image and pattern sizes of up to 16,384 × 16,384 pixels and minimum dwell times of approximately 50–250 ns, depending on the operating mode. These figures are project claims rather than universal performance guarantees.
OBI is designed with open hardware and software across several layers, including PCB design, firmware, FPGA-related components, host software and configuration interfaces. The project uses tools such as KiCad, Python and Amaranth, with documentation covering installation, microscope interfaces, timing, coordinate transforms, scripting and software configuration.
The system is not a plug-and-play replacement for every SEM. Installation requires a functioning microscope, accessible detector and scan signals, suitable electrical connections and microscope-specific configuration and calibration. OBI is therefore aimed mainly at experienced microscope maintainers, university engineering groups and makerspaces seeking an open approach to modernising otherwise usable legacy equipment.
