Method for improving terahertz band absorption spectrum measurement accuracy using noncontact sample thickness...

Area of Science:

• Spectroscopy
• Materials Science
• Metrology

Background:

• Terahertz (THz) absorption spectra exhibit a complex, nonlinear relationship with sample thickness.
• Traditional mechanical thickness measurements lack accuracy, leading to incorrect spectral determinations.
• Precise sample thickness is crucial for accurate THz absorption spectrum analysis.

Purpose of the Study:

• To develop an iterative algorithm for accurate sample thickness determination in THz spectroscopy.
• To overcome the limitations of conventional mechanical measurement methods.
• To improve the precision of extracted terahertz absorption spectra.

Main Methods:

• An iterative algorithm was developed, independent of initial values, ensuring convergent calculations.
• The algorithm enhances precision in sample thickness measurement up to 0.1 μm.
• Quantitative analysis involved comparing the proposed method with traditional mechanical measurements using a three-component amino acid mixture.

Main Results:

• The iterative algorithm accurately determines sample thickness, improving precision to 0.1 μm.
• A more precise terahertz absorption spectrum can be extracted using the algorithm.
• Experimental results showed a decrease in global error from 0.0338 to 0.0301 compared to the traditional method.

Conclusions:

• The proposed iterative algorithm provides a robust and accurate method for determining sample thickness in THz spectroscopy.
• This advancement leads to more reliable terahertz absorption spectrum data.
• The method demonstrates significant error reduction in quantitative analysis of complex mixtures.