Abstract: An analog, optical-fiber measuring system compensates for variations in the level of light attenuation occurring in the optical path of the measuring system. The analog, optical-fiber measuring system utilizes a "reference" light transmitted along a common optical-fiber path as the actual "sensing" light. The reference light has a wavelength which differs from the sensing light's wavelength. Effects of the variations in the level of light attenuation are eliminated by monitoring the variations in the attenuation experienced by the reference light along the common optical-fiber path and adjusting the respective intensities of the reference light and the sensing light as a function of the variations. Because the effects of the variations in the level of light attenuation are compensated by an analog scheme, accurate measurement of the selected physical parameter is insured without the need for a microprocessor.