Application of point diffraction interferometry for measuring angular displacement to a sensitivity of 0.01 arcsec.

The use of point diffraction interferometry is reported for measuring minutes, on the order of 0.01 arcsec angular movements. The algorithm for determining the angular displacement by the dynamics of the interference pattern is described. We also demonstrate results for applying this method to the study of the linearity and hysteresis of the angular shift of the platform, controlled by piezo actuators, which are designed for angular adjustment of the mirror of a solar extreme-ultraviolet telescope.