衍射光栅在正常照明条件下,用单色平行光束在衍射光的自成像平面上形成与它周期相等的精确条纹。衍射光栅这一性质可用来测量均匀物体的折射率。对于这种研究方法可选择一个同振幅的正弦衍射光栅,在折射率n_0=1的介质中,它把入射光束分为三个级次(见图1)。 Diffraction Gratings Under normal lighting conditions, a monochromatic parallel beam forms an exact stripe on the self-imaging plane of the diffracted light equal to its period. The property of a diffraction grating can be used to measure the refractive index of a homogeneous object. For this method, a sinusoidal diffraction grating with the same amplitude can be chosen. In the medium of refractive index n_0 = 1, it divides the incident beam into three orders (see Figure 1).