Page quantitative determination device and methods based on terahertz time-domain spectroscopic technology

Abstract

The invention discloses a paper sheet quantitative detection device which is based on a terahertz time-domain spectroscopy technology and a method thereof. The detection device includes: a femtosecond laser, a beam splitter, an optical delay device, a reflective mirror, a focusing lens, a photoconductive antenna type terahertz transmitter, a polyethylene lens, a polarizer, a zinc telluride electro-optical crystal, a phase-locking amplifier, a high-power amplifier and a data collection and processing system. The invention makes use of the polyethylene lens for aligning the terahertz waves to the parallel light beams, and the polyethylene lens is used for focusing the terahertz waves on a terahertz detector after penetrating the paper sheet. The paper sheet quantitative detection method which is disclosed by the invention firstly establishes a paper sheet quantitative detection mathematical model, then respectively measures the time-domain signals of the terahertz waves penetrating the air and penetrating the paper sheet, extracts the delay time and applies the established mathematical model to calculate the paper sheet quantitative value. The invention has high precision of the measurement, strong anti-interference capability, small influence of multiple reflections and safe usage, so the invention can be used in the precise paper sheet quantitative detection of the field of paper making.

Description

technical field [0001] The invention belongs to the application field of terahertz technology, and in particular relates to a paper sheet quantitative detection device and method based on terahertz time-domain spectroscopy technology. Background technique [0002] Terahertz (1THz=10 12 Hz) waves generally refer to electromagnetic wave radiation with a frequency ranging from 0.1 THz to 10 THz, which is between microwaves and infrared light. The terahertz wave technology has the following characteristics: (1) The terahertz time-domain spectroscopy technology adopts the optical pulse sampling detection method, which can obtain the transient electric field of the terahertz wave, that is, obtain the amplitude and phase information at the same time. (2) Terahertz radiation has a high transmittance to many substances such as ceramics, plastics, and dry wood chips, and can be used for quality control of these materials. (3) Terahertz radiation is a very safe electromagnetic radiat...

AI Technical Summary

Problems solved by technology

This method uses the amplitude information of β-rays for quantitative detection of paper sheets, which is easily affected by scattering and diffuse reflection, and most of the ray sources used to generate β-rays are harmful to the human body and have radioactive pollution.

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