Preparation method of middle cavity layer of multi-channel spectrum optical filter

A preparation method of an intermediate cavity layer of a multichannel spectrum optical filter belongs to the technical field of optical optical filters and optical thin films, and comprises the following steps: spin-coating a negative photoresist with good stability and high transparency on a high-reflection film stack of the spectrum optical filter to serve as the intermediate cavity layer of the spectrum optical filter; and performing one-time stepped exposure on the spin-coated photoresist by adopting a laser direct writing method to form middle cavity layers which are different in size and thickness and are periodically arranged in an array manner, thereby realizing peak position regulation and control on a plurality of spectrum channels of the optical filter. According to the method, spin-coated photoresist is used for replacing a traditional dielectric material prepared in a film coating mode to serve as a middle cavity layer, and laser direct-writing stepped exposure is used for replacing a traditiona