Abstract: A system and method for initializing and calibrating a fiber optic pressure transducer so that a measured intensity of light which varies as a function of pressure can be accurately translated to the value of pressure which produces that value of light intensity. The transducer includes an enclosed sensor tip having a diaphragm which is exposed to atmospheric pressure on the inside and the pressure to be determined on the outside as measurements are taken, the resulting pressure differential producing a related attenuation in light intensity. Calibration according to the present invention is performed by exposing the diaphragm to atmospheric pressure on the outside and sub-atmospheric pressure on the inside while transmitting light through the fiber in the usual manner. The sub-atmospheric pressure is changed gradually as simultaneous measurements are made of the intensity of light returned through the fiber and the actual value of the sub-atmospheric pressure at a number of discrete times.

Abstract: Method and apparatus are disclosed for measuring and controlling the concentration of oxygen in a gas. A sensor (10) is provided having a zirconium dioxide wall (12). One side of the wall is exposed to a reference gas having a known oxygen concentration while the other side is exposed to a gas having the unknown oxygen concentration. An electrical potential is developed at the sensor output, where the magnitude of the potential is dependent upon the relative oxygen concentrations on either side of the sensor wall and the temperature of the wall. The reference gas is selected such that variations in the electrical potential due to temperature changes are minimized over the expected range of temperatures to which the sensor will be subjected during the oxygen concentration measurements and over the range of oxygen concentrations which must be measured.The sensor temperature is measured by measuring the resistance of the sensor, which varies directly with temperature.

Abstract: A detector for detecting the position of the edges of a moving strip which produces an electrical signal proportional to the transverse position of the strip. A light source shines on the edge of the strip. A smooth surfaced sheet of translucent plastic material containing a fluorescent pigment is placed below the edge and opposite the light source. The pigment in the portion of the sheet of the strip and exposed to the light source outside the edge fluoresces producing light energy in amounts proportional to the area of the sheet exposed to the light source. This light energy travels between the sheet surfaces to the edges of the sheet. Photoelectric sensitive means are operatively associated with the edges of the sheet for producing an electrical signal proportional to the amount of fluorescent generated light energy which signal can be amplified to control power means for respositioning the strip.