Adjustable near-infrared filter

The invention provides an adjustable near-infrared filter, and belongs to the technical field of optical filtering. The defect that an existing adjustable near-infrared filtering system is high in cost is overcome. The adjustable near-infrared filter comprises a first glass substrate and a second glass substrate which are oppositely arranged, the two opposite sides of the first glass substrate and the second glass substrate are each provided with a transparent conducting thin film layer, and an adjustable material layer is arranged between the transparent conducting thin film layers. The adjustable material layer is a smectic liquid crystal layer or a liquid crystal layer with a preset direction, and the liquid crystal layer with the preset direction comprises two orientation layers and a guest-host liquid crystal layer located between the two orientation layers. The guest-host liquid crystal layer comprises liquid crystals which are evenly distributed and dichroic near-infrared absorbing dyes, a sealing rubber layer is arranged on the periphery of the liquid crystal layer, and the upper end and the lower end of the sealing rubber layer are in sealing connection with the two transparent conducting thin film layers respectively. The filter which is prepared by the unique optical property of special liquid crystals is simple in structure, convenient to operate, capable of conducting selective absorption to near-infrared light beams according to needs, and suitable for near-infrared filtering systems.