The invention is suitable for the technical field of filters, and particularly relates to a manufacturing method of a
linear gradient filter and the
linear gradient filter. The manufacturing method of the
linear gradient filter comprises the following steps that a glass
wafer serves as a substrate, and a lower reflecting layer is plated on the surface of the glass
wafer; wherein the lower reflecting layer is formed by alternately stacking a plurality of
layers of low-refractive-index materials and a plurality of
layers of high-refractive-index materials;
coating a
resonant cavity layer on one side, far away from the glass
wafer, of the lower reflecting layer through a stepped
coating process; plating a reflecting layer on one side, far away from the glass wafer, of the
resonant cavity layer; and plating a long-wave-pass layer on one side, far away from the glass wafer, of the upper reflecting layer and in an area larger than the central
wavelength to obtain the linear gradient filter. Compared with the prior art, the linear gradient filter provided by the invention is better in
spectral resolution in a long
wave band, smaller in energy difference of channels, excellent in
wavelength selection performance and capable of being applied to spectrum applications such as a miniaturized
infrared spectrometer and the like.