Abstract: A fiber optic sensor system includes a first optical power source which icts a light pulse into an optical fiber loop system. The light pulse circulates in the optical fiber loop system at a circulation frequency. The optical fiber loop system includes a transducer which modulates the circulation frequency in response to detecting a changing physical condition, a filter, polarization controller, an isolator, and an optical fiber gain medium for amplifying the light pulse. A second optical power source provides optical energy to the optical fiber gain medium. A detector system transforms a portion of the light pulse received from the optical fiber loop system into an output signal representing the circulation frequency.

Abstract: A sensor for remotely detecting an angular position of a shaft rotatable within a frame includes: first means for generating collimated first, second, third, and polarized optical beams; second means positioned proximate to the first means for receiving and combining the first, second, third, and polarized optical beams into a composite optical beam having an intensity; and a code wheel fixedly mounted to the shaft and interposed between the first and second means. The code wheel includes first, second, and third channel mask patterns and a first polarizing filter positioned to transect the first, second, third, and polarized optical beams, respectively. Interaction between the code wheel and the light beams results in the composite light beam being encoded such that the angular position of the wheel is functionally related to the intensity of the composite opitical beam.

Abstract: A sensor provides remote angular orientation sensing. A rotational signal transmitted to a rotatable input shaft mounted in an encoder body causes the shaft to rotate. Light signals are transmitted through a digital code wheel mounted to the shaft. As the code wheel and shaft rotate, the light signals passing through the code wheel are superimposed with light pulses corresponding to incremental and directional changes of angular position of the code wheel with respect to the encoder body. The light signals are propagated through an optical fiber to a remote combination digital and analog circuit which converts them into a digital representation of the angular position of the code wheel.

Abstract: A method for remotely detecting the angular position of a rotatable code wheel is provided by generating two sine wave modulated light beams which are orthogonally polarized with respect to each other. The beams are combined and then directed through a polarization filter mounted on the code wheel. The combined beam incurs a phase shift with respect to a reference signal which depends upon the position of the code wheel. The combined polarized beam provides angular position resolution between zero and ninety degrees, but lacks quadrant resolution. Two other light beams are directed to a two channel digital mask pattern imprinted on the code wheel. The mask pattern encodes these latter beams with "on" or "off" pulses to provide quadrant resolution. The beams are converted to digital electric signals which are received by a programmable read oly memory (PROM). The PROM provides an output corresponding to the angular position of the code wheel to a display.

Abstract: Longitudinal tensile and/or compressive strain in optical fibers is detered by an entirely optical technique. A test optical fiber optically coupled to optical injection and extraction couplers form an optically recirculating loop. A semiconductor laser diode feeds a series of narrow light pulses into the loop via the injection coupler and an oscilloscope or signal peak detector give visual indications of optical correlation when an avalanche photodiode provides responsive signals coming from the extraction coupler. Straining the optical test fiber will change the loop's length and, hence, the time delay between reoccurring pulses so that the loop frequency of the narrow optical pulses must be correspondingly changed to provide maximum signal correlation. Changing the pulse repetition rate of the laser diode until a maximum correlated signal is observed at the scope or detector provides a new resonant loop frequency that is proportional to strain.

Abstract: A combination optical time domain reflectometer (OTDR) and insertion loss measurement system evaluates environmental stress effects on a test fiberoptic cable. A multiport coupler joins the OTDR and insertion loss system to the test fiberoptic cable via a precursor of like type and length with respect to the test cable. Nondestructive analysis, continuously and throughout, measures attenuation between any two points within the equilibrium region of the test cable, the quality of the splice between the precursor and the test cable and the degree of EMD disruption. Attenuation measurements over operating environmental conditions can be made to precisely determine the maximum allowable cable length. Visual readouts and permanent records of the EMD disruption and resultant excess attenuation provide real time analysis so that responsive corrective actions can be made.

Abstract: Disclosed is an optical beam steering system having a plurality of optical apertures arranged in a circle. Each of the optical apertures corresponds to a unique angular sector of the circle and includes a blazed fiber Bragg grating that responds to selected wavelengths of light. A particular angular sector of the optical system can selectively be made to project a radially directed light beam based upon the light used. The direction of the light projecting from a chosen angular sector can be altered by further tuning the light and can also be changed by expanding or contracting the length of the blazed fiber Bragg grating employed.