Faseroptischer Drucksenor

A fibre-optic pressure sensor for measuring the movement of a pressure diaphragm (25) has a transmission fibre (9) which is split into a reference fibre (12) and a sensor fibre (13) in a three-way coupler (11). The length of the sensor fibre (13) deviates considerably from the length of the reference fibre (12). The intensity of the light which can be fed into the transmission fibre (9) is split between the reference fibre (12) and the sensor fibre (13) in the 3-way coupler (11). A sensor branch lens (39) for imaging a parallel sensor light bundle (42) on the pressure diaphragm (25) is arranged normally in relation to the optical axis (48) of the sensor fibre (13). A reference branch lens (19) arranged normally in relation to the optical axis (33) of the reference fibre (12) generates a parallel reference light bundle and the centre (35) of the pressure diaphragm which only moves axially in relation to the axis (33) when a pressure change occurs. The sensor light bundle (42) impinges o n a lateral pressure diaphragm region (43) if there is a pressure change causing a change in angle. The optical axis (48) of the sensor light bundle (42) is at an angle of no more of a few degrees in relation to the normal on the lateral surface (43) of the pressure diaphragm (25) illuminated by the sensor light bundle (42).