What is a linear graduated filter?
Linear gradient filters are so-called "linear" because their spectral characteristics are different at different positions and change linearly with the change of spatial position. Linear gradient filters have the advantages of wavelength gradient, channel selection, and stable performance, etc. The spectral characteristics of the filters vary linearly due to the use of ion-assisted or ion-beam sputtering processes, and the formation of wedge-shaped film layers by plating a multilayered film system with varying thicknesses on the substrate surface.
...