Abstract: Gases in the atmosphere are detected remotely using a Raman-shifted excimer/dye laser beam formed by passing an excimer/dye laser beam through a circulating-medium Raman-shifting cell which significantly increases the measurement repetition rate and allows for the production of an infinite number of different wavelengths for measurement. The Raman-active medium is continuously circulated so that the inputted laser beam passes through the Raman-active medium when the molecules of the medium in the optical path are at their ground energy level state. The Raman cell is then tuned to provide a first wavelength, preselected for nonabsorption by the gases to be detected, which is transmitted through the gases to be detected toward an object capable of reflecting the beam back. The Raman cell is also tuned to provide a second wavelength, preselected for being highly absorbed by the gases to be detected, which is then transmitted and similarly reflected.