Systems, methods, and computer readable medium are provided for determining interferometric data and spectral data associated with combustion conditions of a flame in a combustion chamber using a sensor head including a first vacuum cavity, a diaphragm operatively interfaced to an inner portion of the combustion chamber, and an optical sensor interrogator configured on a computing device and coupled to the sensor head via optical fibers. The optical sensor interrogator including an interferometer configured to determine interferometric data associated with the flame based on light transmitted and reflected via a first optical fiber and a spectrometer configured to determine spectral data associated with the flame based on light transmitted via a second optical fiber.