Source: Nature

Understanding Fourier Transform Spectroscopy

Operation Principle

Fourier transform spectroscopy is a method used in various spectroscopic techniques, especially in infrared spectroscopy. It involves computing an optical spectrum from raw data by applying a Fourier transform algorithm. The method is based on measuring the interference signal in the time domain using an interferometer.

How It Works

In Fourier transform spectroscopy, the electromagnetic radiation under investigation is directed into an interferometer, typically a Michelson interferometer. By varying the arm length difference in the interferometer, and measuring the optical power at the output, an interferogram is obtained. Applying a Fourier transform to this data allows the retrieval of the optical spectrum.

Applications and Practical Aspects

Fourier transform spectroscopy finds extensive use in measuring optical spectra of light sources and material properties like transmissivity and reflectivity. The method is particularly advantageous in the mid and far infrared regions where conventional spectrographs face limitations. It offers improved signal-to-noise ratio and spectral efficiency compared to other methods.

Reducing Mechanical Noise

Sensitivity to mechanical noise in interferometers can be reduced by employing common-path interferometers based on birefringence. This setup minimizes the impact of vibrations and inaccuracies in the optical delay line, making it suitable for short-wavelength Fourier transform spectroscopy applications.

Conclusion

Fourier transform spectroscopy is a powerful technique for analyzing optical spectra, especially in the infrared range. By utilizing Fourier transforms, it enables high-resolution spectroscopic measurements with improved signal quality and efficiency, making it a valuable tool in various scientific and technical fields.

Source: YouTube
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