New developments in interference spectroscopy

Publisher Website
Google Scholar
Abstract
After an introduction (Part I) dealing with the different possibilities of classifying the methods of interference spectroscopy, Part II deals with the more recent developments in Fabry-Perot spectroscopy. A complete theory, including the role of surface imperfections and of field diaphragm, is given, and the recent improvements in dielectric coating are reviewed. A complete outline of the photoelectric use of the Fabry-Perot (Fabry-Perot ` spectrometer ') is given, including: methods of scanning for low and high resolutions, best compromise between luminosity and resolution, calculation of the luminosity and extensions of the Fabry-Perot method to studies of absorption spectra. The properties of a new ` spherical Fabry-Perot ' spectrometer are described. Some recent results obtained with photographic methods are briefly discussed. Part III deals with a new type of spectrometer which selects the different wavelengths by the amplitude of the modulation given to them by a linear variation of optical path. Such an instrument using gratings, for instance, is capable of yielding the same resolution as would be obtained if one of the gratings was used in a conventional fashion with very narrow slits, but it provides a much higher luminosity. The spectrum is directly recorded in the usual form. Part IV deals with methods of selecting the different wavelengths by the frequency of their interferometric modulation: the spectrum is not directly given in the usual form, but in the form of interferogram which is the Fourier transform of the spectrum. The main advantage of these methods is that, in common with the photographic method, the time required for recording the interferogram does not depend on the width of the spectrum studied. The resolving power and the luminosity of the process are studied. Some methods of application are described, as well as the different methods of reconstitution of the spectrum from the interferogram. Some recent applications of Michelson's method of ` visibility of fringes ' are also reviewed.