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Delay compensation: its effect in reducing sampling errors in Fourier spectroscopy
Applied Optics
|March 9, 2010
Summary
This study derives a formula for spectrum ghosts in Michelson interferometers caused by drive speed variations. Delayed sampling significantly reduces ghost amplitudes, making them much smaller than velocity errors, especially in lower frequency bands.
Area of Science:
- Optics and Photonics
- Signal Processing
Background:
- Periodic drive speed variations in Michelson interferometers can cause spectrum ghosts.
- These ghosts can contaminate spectral measurements, particularly in fringe-controlled sampling systems.
Purpose of the Study:
- To derive an approximate formula for spectrum ghosts caused by periodic drive speed variations.
- To evaluate the effectiveness of delayed sampling in mitigating these spectral artifacts.
Main Methods:
- Derivation of an approximate formula for spectrum ghosts.
- Application to fringe-controlled sampling with delayed reference fringes.
- Numerical analysis for common low-pass filters (e.g., Butterworth).
Main Results:
- Delayed sampling significantly reduces ghost amplitudes compared to velocity errors.
- In the lower half of the filter band, ghost amplitude is typically 20x smaller.
- In the lowest quarter of the filter band, ghost amplitude is over 100x smaller.
Conclusions:
- Delayed sampling is an effective technique for suppressing spectrum ghosts in Michelson interferometers.
- The derived formula provides a quantitative understanding of ghost reduction with delayed sampling.
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