Study of the Errors in Interpolated Fast Fourier Transform for Interferometric Applications

Frequency estimation is often the basis of various measurement techniques, among which optical distance measurement stands out. One of the most used techniques is interpolated fast Fourier transform due to its simplicity, combined with good performance. In this work, we study the lim-its of this technique in the case of real signals, with reference to a particular interferometric tech-nique known as self-mixing interferometry. The aim of this research is the better understanding of frequency estimation performances in real applications, together with guidance on how to im-prove them in specific optical measurement techniques. An optical rangefinder, based on self-mixing interferometry, has been realized and characterized. The simulation results allow us to explain the limits of the interpolated fast Fourier transform applied to the realized instrument. Fi-nally, a method for overcoming them is proposed by decorrelating the errors between the meas-urements, which can provide a guideline for the design of frequency-modulated interferometric distance meters.