MEASURING THE FIELD FROM A MAGNETIC RECORDING HEAD IN THE SCANNING ELECTRON MICROSCOPE.

Abstract

In optical photography, the schlieren image can show the shock wave from a bullet or from the model of a supersonic airplane in a wind tunnel. A similar effect can be achieved in the SEM by rocking the beam about a point in the plane of a knife edge, contrast aperture, or reference mesh by means of the selected-area electron channeling pattern (SA-ECP) scanning mode. This procedure makes it possible to modify the field-plotting techniques of Thornley and Hutchison (the TH method) and of Rau and Spivak, so that the image now shows the contours of equal beam deflection directly (although at present over a smaller area), rather than in a derived manner. It is pointed out that The TH method can now be used together with the new ideas to give a more powerful combined approach.