Abstract: Improved fiber optics pressure sensor transducers utilizing fiber optics in an interferometer sensing element. Included is a bellows-type pressure-to-movement converter that translates sensed pressure into linear displacement. That displacement is mechanically coupled to, and thereby varies the length of one leg of a fiber optics interferometer as a function of pressure. A temperature compensator is attached to the sensing or reference optical fiber of the interferometer. The temperature compensator causes corrective changes in the length of that optical fiber to which it is attached, thereby compensating for opposing temperature effects on other parts of the interferometer. Threaded studs attached to flexible stress reducers which are in turn coupled to optical fiber grippers provide means for adjusting interferometer optical fiber pre-tension and rotation to optimize polarization.

Abstract: An attachment structure is described that provides means for holding and for applying tensile force to an optical fiber clamped therein. Attachment to an optical fiber is accomplished by stripping the buffer layer(s) from a portion of the fiber and casting a thermosetting polymer encapsulating and compressing member thereon at elevated temperature so that, at lower than the polymer curing temperature, the cast polymer encapsulating member is in compression on the bared fiber and on a short portion of its adjacent buffer layer(s). A tension wire which provides a means for applying external force to the optical fiber has one end inserted axially in the mold for incorporation into the cast encapsulating member. The wire is also placed under compression at temperatures below that of the curing temperature of the polymer. To maintain compression over temperature elevated temperatures, a restrictive cylindrical coil spring is directly engaged around the encapsulating member.

Abstract: A sensing system having a wideband optical source for providing optical illumination having a bandwidth of at least 25 nanometers, and an optical fiber cable for transmitting the optical illumination to a remote location. A transducer responsive to the transmitted optical illumination amplitude modulates the transmitted optical illumination as a function of a monitored physical parameter (for example, pressure or temperature) to provide an amplitude modulated optical illumination having generally sinusoidally varying nulls across the spectrum thereof, the frequency of the nulls varying across the spectrum of the modulated optical illumination and being a function of the monitored physical parameter. The fiber optic cable (or another fiber optic cable, depending on the transducer implementation) transmits the modulated optical illumination to an optical spectral analyzer which provides a spectrally dispersed optical signal indicative of the spectral content and amplitudes of the modulated optical illumination.

Abstract: The method and apparatus for processing bipolar coherent sidelooking radar data to achieve continuous real time synthetic array mapping in the form of focused line-by-line imagery. Received radar data is correlated such that a number of subarrays are vectorially combined with appropriate quadratic phase corrections to continuously form the total synthetic array. Each subarray is accumulated in a recirculating (feedback) channel which applies a linear phase correction and amplitude weighting, which in turn reduces the arithmetic operations required to form the array. The subarrays are updated by continuously subtracting out the oldest data and adding new data to yield continuous line-by-line imagery. Alternate accumulator and feedback channels are employed in an interleaved fashion to minimize the buildup of "round-off" errors which result from digital multiplications. The invention is adaptable to all-range-focusing and operation at various pointing angles.

Abstract: A system for automatically focusing a synthetic array through derivation of focus error signals which may be used such as by summing a priori data so that the synthetic array data may be optimally focused. Focus error data is derived by forming the synthetic array in three sub-array. The resultant outputs of these three sub-arrays are further processed together to extract data corresponding to the degree of total array defocus. For purposes of imagery generation, the phase and amplitudes of these three sub-array resultants are vectorially summed together and the resultant is magnitude detected to yield imagery output corresponding to the full synthetic array. For derivation of focus error data, the mean (bisector of the relative phase angle between the two end sub-array resultant vectors is measured. This derived bisector's phase angle is compared to the phase angle of the central sub-array resultant vector.

Abstract: A thinned array real time radar system having an antenna array with receiving elements spaced more than one wavelength apart and having a dynamic means for programming the focus of the array so that it is time sequentially focused to accommodate radar echoes over a range interval from a near range out to infinity to provide an improvement in azimuth resolution, the improvement being substantially large for the near ranges. The system includes a separate mixer for every element of the array for receiving return energy therefrom and with each mixer having a separate local oscillator input. The local oscillator frequency varies as a prescribed first function during each period of processing over the selected range interval and the path length distribution of the feeds between the local oscillator and each individual mixer vaires as a prescribed second function.