Stereo Height Measurements in Scanning Electron Microscopy

Determination of relative heights from SEM stereo photographs is considered. It is shown that by the choice of suitable geometry it is possible to derive exact formulas for both the case of translating and tilting the specimen. The translation method is shown to be useful for determining the true working distance whereas the tilting method is more sensitive to small height differences. A comparison between exact and approximate (infinite working distance) formulas is made in the specimen tilting case. Experimental requirements are considered and methods are suggested.