What is the name of a translucent plate that can change color?

Its main feature is that its size can be made quite large. Thin film filters are divided into thin film absorption filters and thin film interference filters. In the former, the absorption line is located at the required wavelength by chemical etching on the substrate of a specific material. Generally, the transmission wavelength is long, and it is often used as an infrared filter. The latter is a low-order, multi-stage series solid Fabry-Perot interferometer. Metal-dielectric-metal films or all-dielectric films with high refractive index or low refractive index are alternately formed on a certain substrate by vacuum coating. The choice of material, thickness and series connection mode of the film depends on the required central wavelength and transmission bandwidth λ.