Spectroscopy by grating synthesis.
Spectral information obtained by synthesis of two or more diffraction gratings is studied. Also the case of two gratings with relative motion and the case of N fixed gratings are discussed. We show that, using grating synthesis, it is possible to obtain transfer functions that increase the total obtainable information with respect to the single grating. The possibility of building a synthesis spectroscope is presented, taking into account both the gratings aberration and some construction imperfections. Finally we show that this synthesis method, with a proper numerical elaboration, gives practically the same information as we can obtain with a single equivalent grating.