To obtain a method for observing, measuring, or displaying a reflection high-energy electron diffraction pattern by eliminating inelastic scattered electrons from a reflection high-speed electron diffraction pattern and causing only elastic scattered electrons to reach a fluorescent screen in the reflection high-speed electron diffraction method.

In the reflection high-energy electronic diffraction method, an energy filter 4 is inserted while electrons emitted from an electron gun 1 are reflected from the surface of a sample 2 and projected to a fluorescent screen 3. A rejection voltage as a threshold is applied to a grid at the center of the filter, in elastic scattered electrons are eliminated, the elastic scattered electrons are projected on the fluorescent screen, a diffraction pattern projected by it is observed by a monitor camera 7, and the pattern intensity and background behavior are measured by the computer of a control system 8.