Afocal coupled etalons: experimental confirmation of a high-resolution double-etalon modulator spectrometer

Experimental verification of the properties of a spectroscopic device consisting of two etalons coupled by an afocal system, and which behaves as a high-luminosity single-etalon single-aperture Fabry-Perot spectrometer, has been made. These preliminary results, limited by the available equipment, confirm the predicted theoretical properties of the double-etalon modulator device. As a corollary to this experimental verification, it has been found that successful operation of the device requires very close alignment of the optical axes of the etalons.