Method for measuring refractive index change direction and period of volume holographic grating

The invention provides a method for measuring the refractive index change direction and period of a volume holographic grating. In the first step, a diffractometer is used for measuring the structure of the volume holographic grating, and a first angle and a second angle between an incident light beam and the surface of the volume holographic grating and between a diffracted light beam and the surface of the volume holographic grating are measured. In the second step, according to the Snell's law, a third angle is calculated from the first angle, and a fourth angle is calculated from the second angle. In a third step, according to the Bragg law, a fifth angle is calculated from the third angle and the fourth angle, and a distance d is calculated from the third angle and the fifth angle. In a fourth step, a grating vector is generated as a function of the fifth angle, and the grating vector is perpendicular to the fringe plane within the volumetric holographic grating. 本申请提供一种量测体积全像光栅的折射率变化方向和周期的方法。在第一步骤中，使用衍射