Study on Rapid Detection Technology of THz-TDS Based on the Electro-Optic Sampling
|Course||Measuring Technology and Instruments|
|Keywords||THz-TDS system Coherent detection PIC18F2423 L297/L298 Time delay|
The THz-TDS technology is a broadband THz pulse coherent measurement techniques can detect both the amplitude and phase information of the THz pulse , its spectral information can be obtained by Fourier transform . THz-TDS technology is a spectral detection methods have important applications in many basic research . Domestic commercialization of products based on the technology of THz-TDS , therefore, the development of high-power , miniaturization has important implications , practical THz-TDS . The departure from the practicality of the THz-TDS system , to optimize the system to detect part of the balanced detection unit and the time of the scanning unit . This study include : paper THz-TDS system based on ZnTe electro-optic sampling probe part study to introduce the basic principle of coherent detection of THz radiation pulse , automatically balanced detection unit and provides real-time sampling unit design theory basis. Design a unit based microcontroller PIC18F2423 automatic balance detection (auto-balance) , and used to replace the traditional manual detection mode . The hardware portion of the automatic balancing detection unit including data pre-processing circuit and motion control circuit , motion control circuit used in the core of the device is L297/L298 stepper motor driver chip combination . A modular design of the software portion of the unit of the auto-balance , comprising: a motor drive subroutine , A / D conversion routines and data processing subroutine . For ease of use , design the mechanical structure of the unit package . 4 confirmed through experiments to : automatic balance detection unit normal work , the most important is the unit THz-TDS system operator can reduce the technical threshold , there is conducive to the promotion of the system . 5. This article by a combination of the theoretical analysis and experimental observation , to optimize the original time delay of the mechanical structure of the unit , including: the symmetric spiral reflector , servo control of the motor and both elastic coupling effectively improve the light spot shaking the status quo.