Software-based Simple Lock-in Amplifier and Built-in Sound Card for Compact and Cost-effective Terahertz Time-domain Spectroscopy System

다국어 초록 (Multilingual Abstract)

A typical terahertz time-domain spectroscopy system requires large, expensive, and heavy hardware such as a lock-in amplifier and a function generator. In this study, we replaced the lock-in amplifier and the function generator with a single sound card built into a typical desktop computer to significantly reduce the system size, weight, and cost. The sound card serves two purposes: 1 kHz chopping signal generation and raw data acquisition. A unique software lock-in (Python coding program to eliminate noise from raw data) method was developed and successfully extracted THz time-domain signals with a signal-to-noise ratio of ~40,000 (the intensity ratio between the peak and average noise levels). The built-in sound card with the software lock-in method exhibited sufficiently good performance compared with the hardware-based method.

참고문헌 (Reference)

1 YUFO-IC, "YUFO-IC website"

2 J. Neu, "Tutorial : An introduction to terahertz time domain spectroscopy(THz-TDS)" 124 : 231101-, 2018

3 M. Hangyo, "Terahertz time-domain spectroscopy of solids : A review" 26 : 1661-1690, 2005

4 A. G. Davies, "Terahertz spectroscopy of explosives and drugs" 11 : 18-26, 2008

5 E. P. J. Parrott, "Terahertz spectroscopy : Its future role in medical diagnoses" 1006 : 66-76, 2011

6 J. A. Zeitler, "Terahertz pulsed spectroscopy and imaging in the pharmaceutical setting-A review" 59 : 209-223, 2007

7 Y. Takida, "Security screening system based on terahertz-wave spectroscopic gas detection" 29 : 2529-2537, 2021

8 Github, "SciPy 1.11.3"

9 N. M. Burford, "Review of terahertz photoconductive antenna technology" 56 : 010901-, 2017

10 P. U. Jepsen, "Phase retrieval in terahertz time-domain measurements : A"how to"tutorial" 40 : 395-411, 2019

11 S. Mitryukovskiy, "On the influence of water on THz vibrational spectral features of molecular crystals" 24 : 6107-6125, 2022

12 B. Reinhard, "Metamaterial near-field sensor for deep-subwavelength thickness measurements and sensitive refractometry in the terahertz frequency range" 100 : 221101-, 2012

13 R. Matsunaga, "Higgs amplitude mode in the BCS superconductors Nb1-xTixNInduced by terahertz pulse excitation" 111 : 57002-, 2013

14 W. Withayachumnankul, "Fundamentals of measurement in terahertz time-domain spectroscopy" 35 : 610-637, 2014

15 J. T. Kindt, "Far-infrared dielectric properties of polar liquids probed by femtosecond terahertz pulse spectroscopy" 100 : 10373-10379, 1996

16 S. H. Chun, "Electromagnon with sensitive terahertz magnetochromism in a room-temperature magnetoelectric hexaferrite" 120 : 27202-, 2018

17 J. Kyoung, "Direct in situ observation of the percolation transition in VO2 thin film by peak-shift spectroscopy" 12 : 1065-1073, 2022

18 G. J. Wilmink, "Development of a compact terahertz time-domain spectrometer for the measurement of the optical properties of biological tissues" 16 : 047006-, 2011

19 Y. C. Shen, "Detection and identification of explosives using terahertz pulsed spectroscopic imaging" 86 : 241116-, 2005

20 S. Watanabe, "Compact terahertz time domain spectroscopy system with diffraction-limited spatial resolution" 78 : 103906-, 2007

21 T. Probst, "Compact and low-cost THz QTDS system" 23 : 21972-21982, 2015

22 B. Fischer, "Chemical recognition in terahertz time-domain spectroscopy and imaging" 20 : S246-, 2005

23 D. T. Chuss, "A software-based lock-in measurement for student laboratories" 86 : 154-158, 2018

24 D. Uhl, "A flexible and scalable, fully software-based lock-in amplifier for nonlinear spectroscopy" 92 : 083101-, 2021

25 RandomMoshe, "1 kHz square wave"