SHADE: Absorption spectroscopy enhancement with ambient light estimation and narrow-band detection
Ambient light (AML) limits the usage of absorption spectroscopy to strictly-controlled environments due to its impact on the quality of the signals. In medical applications for Optical instruments that require high reliability and validity results, it is indispensable to control AML impact. In this work, we present a multi-wavelength optical acquisition method, here called SHADE.The technique increases the quality of the optical signals, dynamically assesses AML, and enables mitigating the AML inﬂuence on the data. Our proposed technique involves four primary functions: (1) Multiplexing/demultiplexing of target wavelengths using a frequency-division method; (2) Robust signal recovery using inverse notch ﬁlters; (3) Concurrent AML intensity estimation; (4) A simple post-processing (oﬄine) suppression of AML interference. We introduce the mathematical framework of SHADE to demonstrate the theoretical scope and limitations. SHADE was also experimentally tested by using a digital signal processing board under diﬀerent conditions.The results conﬁrmed the performance of the AML reconstruction and the potential of such a method for further improvements of the signal quality.
Pinto-Orellana, Marco Antonio