Noise evaluation in Hadamard spectroscopy

In dispersive spectroscopy, the measurements tend to be drowned in noise because of poor lighting conditions. Hadamard spectroscopy is a technique that allows better Signal-to-Noise Ratios (SNR) for the measurements. In this paper, we propose a method for measuring the gain in SNR of the experimental model of a Hadamard spectroscope. The instrument addresses THz range spectroscopy but, in order to identify the implementation problems, some first experiments are done in visible domain. The noise is measured in dispersive and Hadamard configurations by using an estimator with a precision of 95% and a gain in SNR is calculated. The obtained gain is 3.52, well below the theoretical Fellgett advantage of 5.68. The reason of the poor gain is the detector behavior that has a higher noise level at high intensity radiation.