Intensity correlation speckles as a technique for removing Doppler broadening

A method involving intensity correlation measurements is described, which allows for the complete removal of Doppler broadening in emission electromagnetic radiation from faraway sources that are inaccessible to conventional Doppler-free measurements. The technique, relying on a correction ${g}^{(2)}$ order ${N}^{\ensuremath{-}1}$, probes separation between neighboring spectral lines and also applicable elimination due collisions ($N$ number emitting particles second-order field function). Possible applications include determination cosmological parameters redshifts gravitationally lensed quasars.