Filter element and projection device

A projection device, comprising:

• an illumination system, a light valve, and a projection lens, wherein the illumination system is adapted to provide an illumination beam, the light valve is located on a transmission path of the illumination beam, and is configured to convert the illumination beam into an image beam, and the projection lens is located on a transmission path of the image beam, and is configured to project the image beam out of the projection device,
• wherein the illumination system comprises a light source module and a filter element, the light source module is configured to emit a plurality of light beams, the illumination beam comprises at least part of the plurality of light beams, the filter element is located on transmission paths of the plurality of light beams and is located between the light source module and the light valve, and the filter element comprises:
• a substrate and a film, wherein the film is located on a surface of the substrate, the film comprises a first area and a second area, the first area comprises a center, the center corresponds to central axes of the plurality of light beams, a distance between the second area and the center is greater than a distance between any point in the first area and the center, and an average thickness of the second area of the film is greater than an average thickness of the first area of the film.