Determination of the change in the refractive index of the active medium of a laser at its emission wavelength

A new method was used in the determination of the refractive index of the active medium of a photodissociation laser at its emission wavelength and at the wavelength of a helium-neon laser. It was found that the refractive index increased with time and with the pressure of the active medium C₃F₇I. The measurement method could be employed in a study of the homogeneity of the active media of lasers at their emission wavelengths.