Method for inversion of material complex refractive index based on rough surface refractive index spectrum

Abstract

The invention discloses a method for inversion of a rough surface complex refractive index based on a refractive index spectrum. The method comprises measuring sample sheet refractive index spectrums of three or more types of different rough surfaces through a Fourier transform spectrometer, measuring an exact solution of a complex refractive index of a polished calibration plate through a far infrared ellipsometer, calculating the surface root-mean-square height of the rough sample sheet through a genetic algorithm, acquiring a linear relationship of the square of the root-mean-square height and the natural logarithm of the refractive index according to Kirchhoff approximation of a Fresnel reflection index, and calculating a refractive index spectrum of a smooth surface through a least square method, wherein the refractive index spectrum is consistent with that of the polished calibration plate. The complex refractive index measured by the ellipsometer is used as an experiment preliminary value, based on a KK theory, the complex refractive index of the material is inversed according to the refractive index spectrum of the smooth surface, and the inversion result is consistent with the measured result of the ellipsometer. The method is suitable for the complex refractive index extraction of sample sheets having rough surfaces, has a wide measurement range, and overcomes the shortcomings such as the complex operation of the experimental system, the limitation of measurement frequency points and rigorous sample processes.

Description

technical field [0001] The invention belongs to the field of dispersion analysis and complex refractive index measurement of medium materials with rough surfaces, and involves the numerical calculation of smooth surface reflectance spectra by using the rough surface reflectance spectrum, and the joint inversion of material complex refraction by combining far-infrared spectroscopic ellipsometer and Fourier reflection spectrometer The rate method can be applied to the dispersion analysis of rough surface materials and the modeling of target scattering characteristics. Background technique [0002] The optical properties of materials, such as complex refractive index, magnetic permeability, and surface impedance, are physical quantities used to characterize the dispersion properties of materials, which indirectly reflect the microscopic mechanism inside the material, and are also an important basis for modeling target scattering properties and radar detection technology . Howe...

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Problems solved by technology

[0005] 1. Strict requirements for the measurement environment: For experimental measurements in terahertz and other frequency bands, the vacuum environment needs to be strictly controlled, and some equipment also requires liquid helium to provide a low-temperature environment;

[0006] 2. Limited measurement frequency points: Due to the limitations of radiation source technology, most experimental equipment can only measure optical constants at a certain frequency point or within a limited frequency range, which limits the analysis of material dispersion characteristics within a wide frequency range;

[0007] 3. Strict requirements for samples: Optical measurement experiments require smooth surface of the sample, strict control of surface oxidation degree, doping degree, coating thickness, etc., which increases the cost of the experiment

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