Related Experiment Video
Updated: May 25, 2026
07:55
High-speed Continuous-wave Stimulated Brillouin Scattering Spectrometer for Material Analysis
Published on: September 22, 2017
[Analysis of collimation error in Fourier transform infrared spectrometer based on step mirrors]
Jin-Guang Lü1, Zhong-Zhu Liang, Jian-Guo Fu
1State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China. jinguanglv@163.com
Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu
|January 19, 2012
Summary
Collimation errors in Fourier transform spectrometers cause interferogram contrast reversal and spectrogram noise. Increased beam divergence significantly degrades signal-to-noise ratio and resolution.
Area of Science:
- Spectroscopy
- Optical Engineering
Context:
- Fourier transform spectrometers (FTS) are susceptible to collimation errors.
- These errors impact interferogram quality and spectrogram data.
Purpose:
- To investigate the effects of collimation error on FTS performance.
- To analyze the relationship between beam divergence and signal quality.
Summary:
- Collimation errors induce contrast reversal in interferograms and side slope noise in spectrograms.
- Analysis shows that a beam divergence factor of 0.15 degrees x mm(-1) can decrease signal-to-noise ratio by 6 dB and worsen resolution to 13.4 cm(-1).
Impact:
- Highlights the critical need for precise optical alignment in FTS.
- Provides quantitative data on performance degradation, informing instrument design and calibration.
Related Concept Videos
01:25IR Spectrometers
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...
01:09Infrared (IR) Spectroscopy: Overview
When electromagnetic radiation passes through a material, atoms or molecules transition from a lower to a higher energy state by absorbing radiation corresponding to the energy difference between the two states. The absorption of infrared (IR) radiation causes transitions between vibrational energy levels in a molecule. Therefore, IR spectroscopy is a useful analytical tool for determining the molecular structure of molecules.
Different compounds display unique properties due to their...
Different compounds display unique properties due to their...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...