Abstract: The present accelerometer uses the total light reflection of a prism for suring an acceleration force by disturbing such total reflection in accordance with the displacement or deflection of a body located close to a boundary surface of said prism, and responsive to the movement of an inertia mass which in turn responds to the acceleration force. The reflected light is measured by a photosensitive device and the resulting electrical signal is a direct measure for the size of the acceleration force. In order to make the measuring of the acceleration force independent of variations in the intensity of the light emitted by a light source used as part of the accelerometer, a reference signal may also be produced to form a quotient of the measured signal and the reference signal.