An optical device composed of a plurality of parallel slits of equal width and the like is called a grating. Generally, the commonly used grating is made by engraving a large number of parallel nicks on the glass sheet, and the nick is an opaque portion, and the smooth portion between the two nicks can transmit light, which is equivalent to a slit. The refined grating engraves thousands or even tens of thousands of nicks in a width of 1 cm. Such a grating that utilizes transmitted light diffraction is called a transmission grating, and a grating that diffracts the reflected light between the two indentations, such as a plurality of parallel indentations on a surface coated with a metal layer, and a smooth metal between the two indentations. The surface can reflect light, and this grating is called a reflection grating.

Gratings are a combination of digital technology and traditional printing technology that can produce different special effects on special film. On the plane, you can see a vivid three-dimensional world, a movie-like smooth animation, and an incredible magical effect. The grating is a sheet of strip lenses. When we look at the side of the lens, we will see an image on a very thin line on the other side of the sheet, and the position of this line is observed from the angle of view. Decide. If we compare these images on different lines, corresponding to the width of each lens, they are printed in sequence on the back side of the grating sheet. When we look through the lens from different angles, we will see different images.