Method and system for simultaneous measurement of refractive index and thickness based on spectral domain interferometer

Abstract

The invention discloses a method and system for synchronously measuring refractive index and thickness based on a spectral domain interferometer. Based on a spectral domain low-coherence interferometric detection system, a part of the light beam penetrates the measured sample by inserting the measured sample into the optical path of the sample arm. The other part of the light beam does not pass through the sample to be measured, and both parts of the light are irradiated on a flat mirror and returned to the system through reflection. A set of interference signals is formed between the light returning from the front and back surfaces of the tested sample, and another set of interference signals is formed between the light beams reflected from the plane mirror in the sample arm, penetrating the tested sample and not passing through the sample The spectrum of the two sets of interference signals is detected by a spectrometer, and the data is collected and processed by a computer, and the thickness and refractive index information of the measured sample can be obtained at the same time. The measurement system has the advantages that no components in the system need to be moved, the structure is stable, and the refractive index and thickness information of the measured sample can be obtained at the same time with only one measurement.

Description

technical field [0001] The present invention relates to spectral domain interferometry (Spectral interferometry) technology, in particular to a method and system for synchronously measuring refractive index and thickness based on spectral domain interferometer. Background technique [0002] Refractive index is an important parameter to characterize the optical properties of materials, and has a wide range of influences on scientific research and industrial fields such as optical design and light wave propagation. The refractive index is related to the microstructure of the material itself, and changes with external parameters such as temperature, electromagnetic field, pressure, etc., resulting in a series of optical phenomena, such as light dispersion effect, Kerr effect, Faraday effect, photoelastic effect Wait. Therefore, it is of great significance to accurately measure the refractive index of materials and the functional relationship between refractive index and extern...

AI Technical Summary

Problems solved by technology

Specifically, white light spectral interferometry requires precise movement of the reference mirror of the Michelson interferometer7; based on Fabry-Perot interferometry and improved OCT technology, it is necessary to precisely control the rotation angle of the sample itself8,9; this This kind of precise movement itself is difficult to achieve high precision, resulting in a large system error

The double-arm white light Michelson interferometer does not need to move the system components and samples5,6, but it needs to place the measured sample close to the reference mirror, which makes it difficult to put the measured sample in to change the external parameters (temperature, pressure, etc.) etc.) equipment

Moreover, the above prior art requires two measurements of the two states of placing and not placing the sample to be able to measure the geometric thickness and refractive index information of the measured sample; this two-measurement mode is bound to be due to the inconsistent , leading to an increase in measurement error; and this two-measurement mode has low work efficiency

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