Light Injection & Collection Apparatus for TEMs: Facilitating Light-Enhanced Electron Microscopy

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Transmission electron microscopy (TEM) is expanding across semiconductor metrology & inspection (M&I) and biological cryo-electron microscopy (cryo-EM), yet both fields share the same bottleneck: insufficient contrast. In cryo-EM, most specimens are weak-phase objects, limiting visualization from single proteins to cells. In M&I, throughput and yield hinge on contrast, especially for 3D reconstructions of next-generation devices.
Complementary photon pathways help: Collecting light by cathodoluminescence (CL) adds band-structure and defect information. Injecting light directly enhances contrast and enables control over the specimen state (e.g. steady-state or ultrafast heating to capture transient configurations).
Commercial solutions have focused mainly on CL, typically sacrificing specimen tilt and preventing the use of frontier TEM techniques such as tomography. Light injection has been inadequately addressed, especially at the high optical powers required, where miniature in-column optics suffer heating, drift, and alignment instability.
Building on ERC Starting Grant NanoEP, we propose ‘Stork’: a compact, affordable, module that integrates with conventional TEMs to both collect and inject light at the specimen. Stork operates across a wide spectral range, delivers dispersion-free injection, and designed to work with state-of-the-art holders (e.g. electrical biasing) and advanced TEMs (e.g. cryo-EM). Installed outside the objective lens pole-pieces, it preserves normal TEM function – enabling full-tilt tomography previously blocked by CL add-ons. By optimizing mechanical and thermal stability, Stork enables robust light-enhanced experiments and new routes to higher contrast. Furthermore, it also contributes to pump–probe studies in ultrafast TEMs.
By providing broadband optical access without geometric penalties, Stork will accelerate the adoption of light-enhanced methods in biological cryo-EM and advanced semiconductor characterization.