Numerical model estimating the capabilities and limitations of the fast Fourier transform technique in absolute...

Area of Science:

• Optical Metrology
• Signal Processing

Background:

• Noncontact absolute distance measurements are crucial in various scientific and industrial applications.
• Existing methods face limitations due to signal processing and digital sampling errors.
• Understanding accuracy limitations is key to improving measurement precision.

Purpose of the Study:

• To develop a numerical model for emulating noncontact absolute distance measurement systems.
• To evaluate accuracy limitations imposed by spectral peak isolation techniques.
• To assess the impact of noise and nonlinearities on measurement precision.

Main Methods:

• Development of a numerical model for noncontact distance measurement simulation.
• Application of windowing functions (Hanning, Blackman, Gaussian) in Fast Fourier Transform (FFT) for spectral peak isolation.
• Modeling of a compound Michelson interferometer for relative length measurements.
• Simulation of ideal data and data with Amplitude Modulation-Frequency Modulation (AM-FM) noise.

Main Results:

• The model successfully emulates noncontact distance measurement capabilities.
• Accuracy limitations were evaluated based on spectral peak isolation methods.
• Precision was projected for both ideal and noisy (AM-FM) simulated data.
• Nonlinearities in the laser scan were identified as the primary limitation to precision.

Conclusions:

• The developed numerical model provides insights into the precision of noncontact distance measurements.
• Spectral analysis techniques and windowing functions influence measurement accuracy.
• Laser scan nonlinearities represent a fundamental challenge for achieving ultimate precision in interferometric measurements.