The preparation method of the
infrared long-wave-pass
optical filter comprises the following steps: S1, cleaning the surface of a product serving as a glass substrate of a lens; s2, the treated lens is put into a tool clamp, the tool clamp with the lens is hung into a cavity of a
vacuum coating machine, and the temperature of the cavity is set to be 200 DEG C; s3, the
vacuum coating machine is started to vacuumize, the vacuum degree reaches 1.0 * 10 <-3 > Pa, and a
radio frequency ion source for auxiliary
coating of the
vacuum coating machine is turned on for cleaning; s4, plating a short-wave-pass film
system on the first surface of the lens; s5, after plating of the short-wave-pass film
system on the first surface of the lens is completed, the tool clamp and the product are taken out after the cavity is cooled to 60-70 DEG C or below; s6, repeating the steps S1 to S3; s7, plating an antireflection film
system on the second surface of the lens; and S8, after plating of the antireflection film system on the second surface of the lens is completed, the tool clamp and the product are taken out after the cavity is cooled to 60-70 DEG C or below.