Available online
Description
The programme examines the principles and constructional features of transmission electron microscopes, in particular the imaging of dislocations.
The programme examines the principles and constructional features of transmission electron microscopes, in particular the imaging of dislocations.
| Module code and title: | ST291, Images and information |
|---|---|
| Item code: | ST291; 13 |
| First transmission date: | 25-08-1977 |
| Published: | 1977 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:00 |
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| Producer: | Ted Smith |
| Contributors: | Harvey Flower; Roger Jones |
| Publisher: | BBC Open University |
| Keyword(s): | Dislocations; Electron microscope; Transmission |
| Footage description: | Barrie Jones introduces the programme. He stands in front of a large electron micrograph which shows moving dislocations in a metal specimen. Ron Jones, at the Department of Metallurgy, Imperial College, London, performs a tensile test on an aluminium specimen. He notes the deformation in the specimen and shows, with aid of a crystal lattice model, how dislocation occurs at the molecular level. Jones goes on to explain the basic principles of the electron microscope. Shots of a schematic diagram of an electron microscope as he talks. Ron Jones and Harvey Flower examine the 100 KeV electron microscope at Imperial College. Flower points out the component parts and explains their function. Flower and Jones look at a thin metal foil specimen under low and then higher (1000X) magnification. Ron Jones explains how a metal specimen is prepared for the electron microscope. Film shots of a spark machine, an electrochemical thinning machine and a jet thinning machine. Shots of the 1 MeV electron microscope at Imperial College. Flower and Jones examine a thin aluminium specimen under this microscope. Jones goes on to compare the normal micrograph mode with the diffraction mode. He uses animated ray diagrams to help illustrate his points. Flower demonstrates the electron microscope in the diffraction mode. He uses an imaging technique, diffraction contrast, to obtain more information from the diffraction pattern than is otherwise possible. Flower then removes the diffraction aperture and shows the image, now under image contrast. He explains how dislocation lines are focussed in this image. Jones and Flower examine a micrograph of a specimen under dark field imaging. Shots of an electron micrograph in which dislocations are seen to move through a crystal. Flower explains what can be learned from studying this movement. Jones and Flower discuss the achievement of electron microscopes and their possible future development and use. Ron Jones sums up. |
| Master spool number: | DOU2396 |
| Production number: | FOUS723A |
| Videofinder number: | 2124 |
| Available to public: | no |
