A gas analysis system and method filter different wavelengths of incident light using a variable light filter at different locations along a length of the variable light filter to form filtered light. The variable light filter is configured to be disposed between a light source generating plural different wavelengths of the incident light and a gas sample. Intensities of wavelengths of the filtered light are determined after the incident light generated by the light source passes through the variable light filter and the gas sample. The gas sample may be identified from among different potential gasses based on the intensity of the one or more wavelengths of the filtered light that is determined by the light detector.