The collections of images below illustrate the effect of the different post-specimen apertures on images recorded using the Electron Microscopy Center's (EMC's) JEOL JEM 3200FS and its Gatan Ultrascan 4000 CCD camera. Details of these apertures are described elsewhere and the important things to bear in mind are that the three objective lens apertures (OLA) and the four high contrast apertures (HCA) are at slighly different post-specimen positions and eliminate electrons that scatter at slightly different angles. The numbering of the apertures is 1 through 3 (or 4) and the diameter of the apertures decreases with increasing position number.
- Waffle Grid at 12,000x:
- Waffle Grid at 50,000x:
Effect of OLA apertures on images of Au/Pd waffle grid
- Waffle Grid at 200,000x: