Multi-step periodic grating structure and preparation method thereof

The invention discloses a multi-step periodic grating structure and a preparation method thereof, and relates to the technical field of micro-displacement detection. Comprising periodic multi-step grating structures, the multi-step grating structure of each period comprises a substrate and a four-step grating structure, the four-step grating structures are arranged on the substrate, and the four-step grating structures are sequentially arranged from right to left in a single period. The three ladder grating structures are respectively a first ladder grating structure, a second ladder grating structure, a third ladder grating structure and a fourth ladder grating structure, and are three layer structure arrays with different heights. Zero-order diffraction light is regulated and weakened through structural improvement, the effect of improving the stability of a laser of a detection system is achieved, the multi-step periodic grating structure prepared through the corresponding preparation method has the zero-o