The Scanning Transmission Electron Holography Microscope (STEHM) is the highest resolution microscope ever built and the only one of its kind in the world. It’s arrival makes the University of Victoria a global leader in the competitive field of advanced microscopy.
Unlike conventional microscopes, which use light to peer at specimens, the STEHM uses an electron beam and holography techniques to observe the inside of materials and their surfaces to an expected resolution smaller than the size of an atom.
The STEHM will see materials beyond the nanoscale to the picoscale. A nanometer is one-billionth of a metre, while a picometre is one-trillionth of a metre. Atoms are typically between 62 and 520 picometres in diameter.
In the world of advanced microscopy, the quality of images depends on the electron source and its lenses. The electron source for the STEHM is about 30 times brighter than existing conventional electron sources. And while standard high-resolution microscopes have about 20 lenses for imaging the specimen, the STEHM has 50.
The STEHM will not only see individual atoms, but it will indicate what type of atoms they are. It also features an electron vortex beam, which researchers can use like tweezers to manipulate individual atoms in a specimen.
The microscope itself is a 4.5-metre tall cylinder encased in metal shielding to block magnetic fields. It has a footprint of six square metres and weighs seven tonnes.
The microscope is so huge that researchers will climb a stepladder to insert their specimens through a tiny airlock into the vacuum of the column. They’ll then leave the room, wait for the air currents in the room to calm, and then operate the microscope remotely from an adjoining room.
The microscope is so sensitive that its image could be affected by little more than a passing cloud. For this reason, it is housed in the basement of UVic’s science building in a special self-contained, extra-tall room that is anchored to bedrock and encased in eight inches of insulation sandwiched between layers of galvanized steel.
The outer walls of the room are shielded with aluminum to block electromagnetic waves, and the inner walls are lined with acoustic and cooling panels to minimize vibration and control temperature variation to no more than 0.1 degrees per hour. The room is also pressure-controlled.
The STEHM was specially built in Japan for UVic by Hitachi High Technologies Canada. It was then transported to Germany where special lenses to correct for image distortion—known as aberration correctors—were installed by CEOS, a company that develops advanced optical components for electron microscopes.
The STEHM is expected to be operational by this fall. Researchers from all branches of science around the world are already vying for time on the STEHM to investigate new materials in areas as diverse as manufacturing, electronics, biotechnology, fuel cell technology, construction and defence.
The STEHM microscope facility is supported by $9.2 million in funding from the Canada Foundation for Innovation, the BC Knowledge Development Fund and UVic, as well as significant in-kind support from Hitachi.
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