Filter device, imaging system and preparation method of filter device

The invention provides a filter device, an imaging system and a preparation method of the filter device. The filtering device comprises a light filtering structure which comprises a light incident surface and a light emergent surface opposite to the light incident surface along a first direction, and the light filtering structure only allows a first light signal which is incident from the light incident surface and has a wavelength not less than a preset wavelength to penetrate through; the light splitting structure is located on the light emitting surface of the light filtering structure, the light splitting structure comprises a plurality of light channels arranged at intervals and isolation walls located between the adjacent light channels, the first light signals emitted from the light emitting surface can penetrate through the light channels, and the isolation walls are used for blocking the first light signals from penetrating through. According to the invention, the filtering effect is improved, and th