System for measuring film thickness by broadband-spectrum light interference method

The invention discloses a system for measuring film thickness by a broadband-spectrum light interference method, and belongs to the technical field of film thickness measurement. The system comprises an ASE (Amplified Spontaneous Emission) light source, a wavelength interrogator, a Fabry-Perot cavity interference platform and the like. According to the system, light output by a laser device is vertically shot on the surface of a reflector, therefore, a Fabry-Perot cavity is formed between an end plane of a collimator and the surface of the reflector, and the interference is formed by two beams of reflected light, therefore the intensity change of interference light can be demodulated by the wavelength interrogator, the length of the Fabry-Perot cavity without a film can be obtained by a phase demodulating method, and then the length of the Fabry-Perot cavity added with the film is obtained by placing a film below a work-piece, raising the reflector and shortening a distance between the reflector and the collimator, and changing the length of the Fabry-Perot cavity, therefore, a differential value between the cavity with the film and the cavity without the film is the film thickness. According to the system provided by the invention, the film thickness can be indirectly obtained by measuring the distance, therefore, a transparent film can be measured, and a non-transparent film can be measured; furthermore, the system is simple in structure, high in measuring precision, and easier to realize.