Method for measuring transmission of interference-insensitive terahertz wave

A measurement method, terahertz technology, applied in the field of terahertz wave transmission measurement, can solve problems such as output power changes and difficulties, and achieve the effects of eliminating measurement errors, reducing influence, high measurement sensitivity and stability

Inactive Publication Date: 2011-10-12
CHINA JILIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, currently commonly used terahertz wave radiation sources, such as return wave oscillators, show certain fluctuations in power and

Method used

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  • Method for measuring transmission of interference-insensitive terahertz wave

Examples

Experimental program
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Effect test

Embodiment 1

[0031] Measurement of trace amounts of glucose in polyethylene powder. The terahertz wave radiation source is the return wave oscillator OV30 of MicroTech Company. Use a polyethylene lens with a focal length of 50 mm to collimate the divergent terahertz waves radiated by this wave source into parallel propagation. The beam splitter is realized by a piece of high-resistance silicon (13~19KΩ·cm) crystal flat sheet. Each branch uses a 100mm polyethylene lens to focus the terahertz wave onto the sample surface. Terahertz waves transmitted through the sample are focused onto a pyroelectric detector using additional polyethylene lenses. The detection signal is recorded by a lock-in amplifier. The reference signal for the lock-in amplifier is provided by a chopper placed in front of the beam splitter. The chopping frequency of the chopper is 30Hz, and the time constant of the lock-in amplifier is 300ms.

[0032] The terahertz wave with a frequency of 350 GHz was selected to meas...

Embodiment 2

[0034] On-line monitoring of wafer resistance value. Silicon wafer is an important raw material for industries such as integrated circuits and solar cells, and whether its resistivity meets the standard directly affects the performance of the final product. Based on the difference in the absorption of terahertz waves by silicon wafers with different resistivities, an online non-contact non-destructive testing based on terahertz wave transmission measurement is established. The detection device is similar to that in Example 1. A high-resistance silicon wafer with a theoretical thickness of 350 μm was detected using the 315.13 GHz terahertz wave output by the return wave oscillator. Firstly, a 350 μm silicon wafer whose resistivity is exactly the middle value of the specified resistivity is selected as a reference sample. Then measure the absorption of the silicon wafer at the upper and lower critical resistivity points as the judgment standard. Finally, the detection of larg...

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Abstract

The invention discloses a method for measuring transmission of an interference-insensitive terahertz wave, which is realized by adopting a terahertz wave beam splitter and two same detection systems. A terahertz wave beam is split into two beams by using the beam splitter, one beam of the terahertz wave beam is used for measuring a sample to be tested to obtain a sample signal, and the other beamof the terahertz wave beam is used for measuring a reference signal to obtain a reference signal, two sample transmissivities obtained through measurement are deducted to obtain a relative transmissivity of the sample to be tested. The selected reference sample and the sample to be tested have same interference characteristics, and floatation caused by an interference effect is effectively reduced. According to the method, the influence of the interference effect of parallel flat samples to the transmission measurement of terahertz waves can be effectively reduced, and measurement errors caused by the power fluctuation of a terahertz wave radiation source is eliminated. The invention has higher measurement sensitivity and stability and is suitable for fields such as micro and trace detection, and the like.

Description

technical field [0001] The invention relates to terahertz wave transmission measurement technology, in particular to a method for using terahertz wave to perform transmission measurement on a parallel flat sample with FP interference effect. Background technique [0002] Terahertz waves generally refer to electromagnetic waves with a frequency between 0.1 THz and 10 THz. Since the intermolecular vibration frequency of macromolecules is also in this frequency band, terahertz waves are widely used in the measurement of the characteristics of macromolecular substances in the fields of biology, medicine, and material science. Through the measurement of the interaction between the sample and the terahertz wave, information such as the refractive index, absorption coefficient, composition, and content of the sample can be obtained. [0003] The characteristics of terahertz waves provide a new means for the micro and trace detection of macromolecular substances. The trace and tra...

Claims

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Application Information

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IPC IPC(8): G01N23/02
Inventor 刘建军何金龙汪伟洪治
Owner CHINA JILIANG UNIV
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