High signal-to-noise ratio optical film thickness control device

The utility model discloses a high-signal-to-noise-ratio optical film thickness control device which comprises a light source, a transmission optical fiber, a spectrometer, a photoelectric signal conversion module and an electric signal processing module which are arranged in sequence. The device is used for controlling the optical film thickness of a surface film layer of a monitoring piece in a vacuum cavity, and a lens module is arranged between a transmission optical fiber and the monitoring piece; the transmission optical fiber comprises a light-in optical fiber and a light-out optical fiber, light of the light source is transmitted to the monitoring piece through the light-in optical fiber and the lens module in sequence, and light reflected from the monitoring piece is transmitted to the spectrometer through the lens module and the light-out optical fiber in sequence; the spectrometer outputs an analog signal corresponding to the light receiving intensity when the light receiving unit receives the ligh