Online film thickness monitoring system and light splitting device for high-resolution narrow-band spectrum

Abstract

The invention discloses an online film thickness monitoring system and a light splitting device for a high-resolution narrow-band spectrum. The system comprises a light source, an emitting unit, a monitoring sheet, a receiving unit, a spectrum light-splitting device, a CCD array signal conversion system and a control acquisition unit. The spectrum light-splitting device comprises an incidence slit, a first collimating objective lens, a plane grating, a second collimating objective lens and a plane reflector. The online film thickness monitoring system for the high-resolution narrow-band spectrum combines the spectrum light-splitting device with a linear array CCD to achieve dynamic monitoring wavelength adjustment, a symmetrical spectrum band with the length of tens of nanometers for the left part and the right part respectively centering on a monitoring wavelength point is formed, a spectrum signal near 100 nanometers is obtained at each monitoring point, the spectrum data quantity islarge, the wavelength resolution is high, the computation of evaluation functions is precise, and a scientific method for achieving high-precision automatic film coating for a spectrum monitoring system in the process of optical coating is provided.

Description

A high-resolution narrow-band spectrum online film thickness monitoring system and spectroscopic device technical field The invention relates to an online monitoring system and a spectroscopic device for optical coating film thickness spectrometry, which are applied to the automatic online film thickness monitoring of the coating process of an optical coating machine. Background technique In the preparation of thin films, in addition to selecting appropriate materials and preparation processes, the thickness must also be precisely controlled. The thickness of the film layer during the coating process cannot be directly measured. Usually, a quantity related to the thickness is monitored, and then the thickness of the film layer is calculated. The theoretical basis of optical thin films is the interference theory of light, so special attention is paid to optical thickness. Currently, the methods of optical thickness monitoring include single-wavelength monitoring method and...

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Problems solved by technology

Through the above formula, the wavelength resolution can be calculated to be 6.5nm, which is not enough for high-precision thin-film products such as narrow-band interference filters.

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