A gas gauge proximity sensor comprising a measurement gas flow channel having an optical pressure sensor for comparing a pressure of the first gas flow and a reference pressure; the optical pressure sensor comprising a first optical cavity fluidly connected to the measurement channel and a second optical cavity fluidly connected to the reference pressure, with the optical cavities being configured to receive electromagnetic radiation and output reflected electromagnetic radiation, the optical pressure sensor further being configured to combine the reflected electromagnetic radiation from the first optical cavity with the reflected electromagnetic radiation from the second optical cavity and determine, based on the combined electromagnetic radiation, a pressure difference between the pressure of the first gas flow and the reference pressure and determine, based on the pressure difference, a distance between the measurement outlet and the measurement object.