Uncertainty in Terahertz Time-Domain Spectroscopy Measurement of Liquids
- 336 Downloads
Terahertz time-domain spectroscopy (THz-TDS) is a significant technique for characterizing materials as it allows fast and broadband measurement of optical constants in the THz regime. The measurement precision of the constants is highly influenced by the complicated measurement procedure and data processing. Taking THz transmission measurement of liquids into account, the sources of error existing in THz-TDS process are identified. The contributions of each source to the uncertainty of optical constants in THz-TDS process are formulated, with particular emphasis on the effect of multilayer reflections and plane wave assumption. As a consequence, an analytical model is proposed for uncertainty evaluation in a THz-TDS measurement of liquids. An actual experiment with a Di 2-Ethyl Hexyl Phthalate (DEHP) sample is carried out to show that the proposed model could be a basis to evaluate the measurement precision of optical constants of liquids.
KeywordsTHz Time-domain spectroscopy (TDS) Measurement uncertainty Optical constant
This study was funded by the National Natural Science Foundation of China (NSFC) (21503045, 61540038); Guizhou Science and Technology Department (J20142107, SY20143065); and General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China (2014QK063).
- 1.Timothy D. Dorney, Richard G. Baraniuk, and Daniel M. Mittleman, “Material parameter estimation with terahertz time-domain spectroscopy,” J. Opt. Soc. Am. A, Vol. 18, No. 7, pp. 1562–1571, 2001.Google Scholar
- 3.P Kužel and H Němec. “Terahertz conductivity in nanoscaled systems: effective medium theory aspects,” J. Phys. D: Appl. Phys. 47 (2014) 374005 (14pp).Google Scholar
- 13.A. B. Ruffin, J. V. Rudd, J. F. Whitaker, S. Feng, and H. G. Winful, Direct Observation of the Gouy Phase Shift with Single-Cycle Terahertz Pulses, Phys. Rev. Lett. Vol. 83, no. 17, pp. 3410–3413, 1999.Google Scholar
- 18.Amin Soltani, David Jahn, Lennart Duschek et al. “Attenuated Total Reflection Terahertz Time-Domain Spectroscopy: Uncertainty Analysis and Reduction Scheme,” IEEE Transactions on Terahertz Science and Technology, 2016, 6(1):32–39.Google Scholar
- 26.R. Wilk, I. Pupeza, R. Cernat, M. Koch, “Highly accurate THz time-domain spectroscopy of multilayers structures,” IEEE Journal of Selected Topics In Quantum Electronics 14, 392–398 (2008).Google Scholar
- 28.P. Juzel, H. Nemec, F. Kadlec, C. Kadlec, “Gouy shift correction for highly accurate refractive index retrieval in time-domain terahertz spectroscopy”, Optics Express, 18, 15 (2010): 15338–15348.Google Scholar
- 29.Rossi G B. The Evaluation of Measurement Uncertainty [M]//Measurement and Probability. Springer Netherlands, 2014:205–221.Google Scholar