Pressure sensor using optical fibers.

A diaphragm-type pressure sensor consisting of three optical fibers is described. A light is projected onto a pressure-receiving diaphragm via a transmitting fiber. A receiving fiber receives the reflected light from the diaphragm. A reference fiber transmits light from an LED back and forth along the same path as the transmitting fiber and the receiving fiber. Division is accomplished by using the reflected signal and the reference signal, so it becomes possible to eliminate apparent pressure variations due to variations in light intensity, which may be caused by external forces and temperature changes. The maximum pressure is 39.3 MPa.