Random error estimation in refractive index measured with the terahertz time domain spectroscopy

This study proposes a practical method to estimate the random error in real part of refractive index measured with terahertz time domain spectroscopy (THz-TDS) for the single measurement of sample by using the phase spectra of the reference terahertz electric field and their standard deviation. The validity of this method is based on the experimental result that the phase correlates with its standard deviation and the signal to noise ratio is almost equal in the phase spectra of reference and sample signal. The random error estimated from the proposed method fitted well to the statistically computed standard deviation.