Measurement of small beam size by the use of SR interferometer

The principle of measurement of the profile or size of small objects through the spatial coherency of the light is known as the van Citterut-Zernike theorem. Recently the SR interferometer (interferometer for synchrotron radiation) was developed to measure the spatial coherency of the visible region of the SR beam, and we demonstrated that this method is able to measure the beam profile and size. Since the small electron beam emits a SR beam which has a good spatial coherency, this method is suitable for measuring a small beam size. In this paper, the basic theory for the measurement of the profile or size of a small object by the spatial coherency of the light, a design of the SR interferometer, and the results of beam profile measurement are described. Two examples of the small beam size measurements are also described.