Dynamic focussing for recording images from tilted samples in small-spot scanning with a transmission electron microscope
✍ Scribed by Zemlin, F.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1989
- Tongue
- English
- Weight
- 580 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0741-0581
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✦ Synopsis
For three-dimensional electron microscopical structure research the specimen must be imaged in a tilted position. Specimen tilt is also often needed to achieve an optimal molecular packing orientation. The tilt with respect to the optical axis causes a defocus gradient alongside the imaged area and thus entails the following complications: 1) The phase-contrast transfer function fades for strong defocus; 2) the Fourier coefficients are split; and 3) the signal-to-noise ratio cannot be enhanced by simple averaging. An image procedure with small-spot scanning and simultaneous defocus compensation is proposed which helps to reduce these problems.