The product is composed of film thickness meter host, PC software of upper computer and optical fiber. When a quasi-monochromatic beam of parallel light is irradiated into the multilayer film, the light waves will be refracted and reflected back and forth between the first and n layers for many times to form a plurality of coherent beams. These coherent beams carry the coherent signal of the multilayer film and return along the original path after the phase-dry superposition. When quasi-monochromatic light of different wavelengths irradiates the film, the interference signals are different. If a beam of quasi-monochromatic light containing a variety of wavelengths is irradiated into the film, the interference signal of each band is extracted, and the optical parameters (thickness, refractive index, extinction coefficient) of each layer of film material can be obtained through the algorithm of OCD's independent intellectual property rights.

The product can be upgraded to monitor films for on-line deposition of vacuum coatings. In the process of multilayer film preparation, real-time online monitoring by the above method can obtain all optical big data during the process of film growth from the beginning to 1 layer, and then growth to n layer. In the process of calculation and analysis, the stop point of each film is output. At the same time, big data in the production process is retained to better control quality and improve product traceability.