Intermediate infrared transmission optical filter and preparation method thereof

The invention discloses an intermediate infrared transmission optical filter and a preparation method thereof, and belongs to the technical field of coating. The optical filter comprises a glass substrate, a narrow-band-pass film system arranged on one side of the glass substrate, and a long-wave-pass film system arranged on the other side of the glass substrate. The narrow-band-pass film system comprises silicon hydroxide/silicon oxynitride film layers and silicon oxide film layers which are alternately deposited layer by layer; the long-wave-pass film system comprises silicon hydroxide/silicon oxynitride film layers and silicon oxide film layers which are alternately deposited layer by layer. The method comprises the following steps: depositing the narrow-band-pass film system on one side of the glass substrate by adopting a magnetron sputtering method, and depositing the long-wave-pass film system on the other side of the glass substrate. The optical filter provided by the inventioncan have high transmitta