A system and method for measuring the refractive index of materials in the terahertz band

Abstract

The invention discloses a system and method for measuring the refractive index of materials in the terahertz band. The system includes a terahertz source, a detector and an electron optical system, wherein the terahertz source generates continuous terahertz radiation waves; the detector receives the terahertz signal; the electric displacement control module in the electron optical system controls the detector to keep collimation and move away from the terahertz source; the signal readout module converts the received terahertz signal into an electrical signal; the signal processing module digitizes the electrical signal After processing and filtering, the periodically changing terahertz signal is analyzed to determine the refractive index. In this method, the two-segment signals scanned by the detector before and after inserting the material are firstly filtered in sections to filter out the DC component, and then the signal is analyzed and processed through Hilbert and other mathematical transformations to obtain the instantaneous phase of the signal, and then according to the inserted material The phase jump values ​​before and after are used to calculate the refractive index. The invention realizes the high-precision material refractive index measurement based on the terahertz continuous wave.

Description

technical field [0001] The invention relates to room temperature terahertz detection technology, in particular to a system and method for measuring the refractive index of different materials in the terahertz band. Background technique [0002] Terahertz (THz for short) waves generally refer to electromagnetic waves with frequencies in the range of 0.3T to 10THz (wavelengths from 30μm to 1mm), which are between submillimeter waves and far infrared. Because terahertz waves have strong penetrating power to many non-polar substances, such as some dielectric materials, plastic films, paper, cloth, etc., terahertz detection technology is also used in quality inspection, safety inspection and industrial non-destructive testing, etc. in the scene. [0003] Over the past two decades, many applications of terahertz technology have been discussed, ranging from spectroscopy of biomolecules, homeland security, terahertz communications, and industrial detection. In industrial testing, ...

AI Technical Summary

Problems solved by technology

However, the optical path of this pulsed terahertz system is complex, using many optical components, the system debugging takes a long time, the efficiency is low, and the cost is high, so the development of a measurement system based on a continuous terahertz source has significant advantages

In addition, there are many methods for measuring the dielectric constant of materials in the microwave band, such as the rectangular waveguide method and the quasi-optical coupling method. These rectangular waveguide systems and quasi-optical components are easy to machine when the size of the microwave band is large, but in the terahertz band, the incident As the wavelength becomes smaller, the size of the corresponding measurement system components is also reduced accordingly, and the processing accuracy is required to be more than 10 microns, which brings great difficulties to machining

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