Stereoscan Mk. I (1)

The Stereoscan Mk1, introduced by the Cambridge Instrument Company in 1965, was the world’s first commercially available scanning electron microscope (SEM), developed from the pioneering work of Professor C.W. Oatley and his team at Cambridge University. It featured a tungsten filament electron gun operating at accelerating voltages between 1 and 20 kV, housed within a three-lens electromagnetic column designed to demagnify the electron beam for high-resolution imaging.

The microscope employed a vacuum system consisting of mineral oil diffusion pumps backed by rotary pumps, which, while effective for the time, sometimes led to contamination issues due to oil vapor deposition. The specimen stage accommodated 12 mm diameter stubs and allowed movement in X, Y, and Z axes, as well as tilt from 0 to 90 degrees, enabling versatile examination of bulk samples.

Imaging was based on an Everhart-Thornley secondary electron detector, converting emitted secondary electrons into light detected by a photomultiplier tube. The resulting image was displayed in real time on a cathode ray tube (CRT) with direct-reading magnification from 50x to 50,000x, covering scanned areas from approximately 2 mm down to 2 micrometres square. Images could be recorded using a 35 mm camera attached to the viewing system.

The Stereoscan Mk1 achieved a resolution of about 50 nm and offered a depth of focus roughly 300 times greater than that of optical microscopes. Controls were manual, and the electronics were based on valve (vacuum tube) technology, requiring careful maintenance. Despite limitations such as vacuum quality and absence of analytical attachments like energy-dispersive X-ray spectroscopy (EDS), the Stereoscan set the standard for future SEM designs and revolutionized surface imaging techniques.

Only around 10 to 20 units of the original Stereoscan Mk1 were produced between 1965 and 1966 before being succeeded by improved models. Its modular design allowed for mechanical and electronic upgrades, reflecting the rapid evolution of electron microscopy technology during that era.

Summary Table: Key Technical Features of the Stereoscan Mk1 (1965)

Vous pourrez trouver sous ce lien 17 modèles d'appareils, 17 avec des images et 9 avec des schémas.
Tous les appareils de Cambridge Scientific Instrument Co.; Cambridge