Abstract: A photoacoustic sensor for spectroscopic gas detection includes a chamber to contain the gas; an excitation laser source that emits a modulated laser beam; a transducer, having a reflective portion, located inside the chamber; an interferometer having first and second arms and an output, the first arm ending in the transducer, and the second arm including an optical path changer element and an actuator connected to the optical path changer element to change the optical path defined by the second arm of the interferometer; a first polarizing beam splitter; a second laser source; a second polarizing beam splitter; a first detector; a second detector; an electronic circuit; and a feedback loop adapted to command the movements of the actuator in order to change and stabilize the optical path of the second arm, so that the difference signal is kept equal to a desired constant value during the gas concentration measurements.

Abstract: An energy conversion device, particularly electromagnetic energy, such as sunlight and the like, comprising a transparent polymer sheet having an edge and a surface, on which said electromagnetic radiation can impact, and a photovoltaic cell mechanically coupled with said edge of said polymer sheet, capable of transforming in an electrical current the radiation incident on it, characterized in that said polymer sheet comprises a polymeric matrix having silicon nanostructures, functionalized with organic binders, said polymeric sheet being then luminescent with respect to a portion of said electromagnetic radiation, so as to convey the same, through a wave-guide, towards said photovoltaic cell. Also disclosed is a method for realizing a polymeric matrix, for the manufacture of a transparent polymer sheet.