Related Experiment Video
Updated: May 2, 2026
06:48
A Multimodal Wide-Field Fourier-Transform Raman Microscope
Published on: December 30, 2025
875
Birefringence measurement in the terahertz range based on double Fourier analysis
Optics Letters
|February 25, 2014
Summary
This study introduces a novel terahertz spectroscopy method to measure birefringent material refractive indexes in one go. The technique also determines optical axis orientation with two measurements.
Area of Science:
- Optics
- Materials Science
- Spectroscopy
Background:
- Terahertz time-domain spectroscopy (THz-TDS) is a powerful tool for material characterization.
- Measuring the refractive index and optical axis of birefringent materials can be complex.
- Accurate optical property determination is crucial for advanced material applications.
Purpose of the Study:
- To present a simplified method for determining average refractive indexes of birefringent materials.
- To enable optical axis orientation determination using THz-TDS.
- To achieve these measurements in a single or minimal number of experimental setups.
Main Methods:
- Utilizing standard terahertz time-domain spectrometer.
- Processing frequency-domain interference between terahertz pulses and echoes via Fourier transform.
- Performing two measurements with varied sample optical axis angles for orientation determination.
Main Results:
- Successful acquisition of average refractive indexes in a single measurement.
- Accurate determination of the optical axis orientation of the material.
- Demonstration of the method's applicability in the terahertz region.
Conclusions:
- The presented method offers an efficient approach for characterizing birefringent materials.
- This technique simplifies the measurement of key optical properties using THz-TDS.
- The findings contribute to advanced material analysis and device development.
Related Concept Videos
01:25IR Spectrometers
3.1K
There are two main infrared (IR) spectrophotometers: dispersive IR spectrometers and Fourier transform infrared (FTIR) spectrometers. In a dispersive IR spectrometer, a beam of infrared radiation produced by a hot wire is divided into two parallel equal-intensity beams using mirrors. One beam passes through the sample, while another is a reference beam. The beams then move through the monochromator, which separates the radiations into a continuous spectrum of different frequencies. The...
3.1K
01:05Total Internal Reflection Fluorescence Microscopy
11.0K
Total internal reflection fluorescence microscopy or TIRF is an advanced microscopic technique used to visualize fluorophores in samples close to a solid surface with a higher refractive index, such as a glass coverslip. TIRF only allows fluorophores in proximity to the solid surface to be excited. When light from a medium with a lower refractive index (such as air) hits the glass coverslip at a critical angle, the light undergoes total internal reflection stead of passing through the glass.
11.0K
01:03IR Frequency Region: Fingerprint Region
2.1K
IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 cm−1. The absorptions resulting from single-bond vibrations of the N–H, C–H, and O–H stretch at higher wavenumbers and appear on the left side of the spectrum. The stretching absorptions of the C≡C and C≡N occur between 2100–2300 cm−1. In contrast, those arising from stretching absorptions of the...
2.1K
01:13Attenuated Total Reflectance (ATR) Infrared Spectroscopy: Overview
1.5K
Attenuated total reflectance (ATR) infrared spectroscopy is a powerful analytical technique used to study the composition of materials. It is widely employed in chemistry, materials science, forensic science, and other fields where sample characterization is required. ATR has several advantages over traditional transmission IR spectroscopy, including the requirement of little to no sample preparation and the ability to analyze a wide range of samples.
The ATR process begins by directing a beam...
The ATR process begins by directing a beam...
1.5K
01:24IR Frequency Region: X–H Stretching
1.5K
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in...
1.5K
01:26Discrete-time Fourier transform
1.5K
The Discrete-Time Fourier Transform (DTFT) is an essential mathematical tool for analyzing discrete-time signals, converting them from the time domain to the frequency domain. This transformation allows for examining the frequency components of discrete signals, providing insights into their spectral characteristics. In the DTFT, the continuous integral used in the continuous-time Fourier transform is replaced by a summation to accommodate the discrete nature of the signal.
One of the notable...
One of the notable...
1.5K