Device for measuring coherence of spin-polarized electron beam and usage method thereof

In the present invention, the path of a spin-polarized electron beam is separated into two by a separator 6. The spinning direction of the electron beam is rotated by a spinning-direction rotating device 8 disposed on a first advancing path B1, and the electron beam is delayed by a first delaying device 10. On a second advancing path B2, the electron beam passes through a sample table. The portions of the spin-polarized electron beam separated into the first advancing path and the second advancing path are made to overlap each other by a biprism 16, and the intensity distribution of the spin-polarized electron beam is measured. The coherence is measured on the basis of the relationship among the spinning-direction rotation angle, the delay time, and the clarity of interference fringes.