Detection of weak interferograms using additive noise

Abstract

All measurement devices have a finite detection limit, which determines the smallest possible non-zero signal that the detector can measure. In the case of the sinusoid crossing (SC) detector, this limit is given by B = Aπ/2N, where A is the amplitude of the reference sinusoid r(t) = A cos(2πf_rt) and N is the number of divisions within a given sampling interval Δ. A signal s(t) is considered weak (or subthreshold) if |s(t)| < B for all t values within the sampling period T = 2MΔ, where: Δ = 1/(2f_r), and 2M is the number of SC's within T.
In this paper, we detect weak interferograms of spectral doublets using a modified version of the SC dithering scheme, where a more accurate interpolation method (sinc interpolation) is utilized in place of the cubic-spline interpolation in Phys. Rev. E 57, 3579 (1998).