SYSTEM AND METHOD FOR MEASURING REFRACTIVE INDEXES OF MATERIALS IN TERAHERTZ WAVEBAND

摘要

A system and method for measuring the refractive indexes of materials in a terahertz waveband. The system comprises a terahertz source (1), a detector (3), and an electro-optical system; the terahertz source (1) generates continuous terahertz radiation waves; the detector (3) receives terahertz signals; an electric displacement control module in the electro-optical system controls the detector to maintain collimation and move in a direction away from the terahertz source; a signal reading module converts received terahertz signals into electric signals; a signal processing module performs digital processing and filtering on the electric signals to obtain periodically changing terahertz signals to analyze and determine the refractive index. The method comprises: first, separately filtering two signals scanned by the detector (3) before and after a sample material (2) is inserted to filter out direct-current components in the signals, then analyzing the signals by means of a mathematical transform such as Hilbert transform to obtain instantaneous phases of the signals, and calculating the refractive index according to a phase jump value before and after the sample material (2) is inserted. The system and method implement high-precision material refractive index measurement based on terahertz continuous waves.