Abstract: System and method for rapidly reconfigurable two-dimensional true time delay generation for phased array antennas is described. The system utilizes a broadband light source, an array of fiber chirp gratings in a single fiber, and an acousto-optic spectrometer to generate a time-delayed linear grating. The grating is subsequently rotated to the desired angle utilizing an acousto-optic device having no moving parts.

Abstract: An acousto-optic tunable filter and filtering method are disclosed providing for a significantly increased number of available wavelength channels for output. The filter combines a diffraction grating, the grating vector of which is transverse to light propagation direction, with an acousto-optic beam deflector, which, by accommodating a narrow spectral bandwidth (about 5% that of conventional acousto-optic tunable filters), provides significantly increased output bandwidth and available wavelength channels (by a factor of approximately 20).

Abstract: A device and method for laser cooling of a solid to extremely low temperature is disclosed, the device including an active cooling structure having a high purity surface passivated direct band gap semiconductor crystal of less than about 3 microns thick and a transparent hemispherical body in optical contact with the crystal. The crystal is itself cooled when illuminated with a laser beam tuned to a frequency no greater than the band gap edge frequency of the crystal. Cooling is caused by emission of photons of higher energy than photons entering the crystal, the additional energy being accounted for by process of absorption of thermal phonons from the crystal lattice.

Abstract: A high speed control apparatus and method utilized in a system having a high pressure fluid supply for producing precisely controlled, amplitude and duration variable thrust are disclosed, the apparatus including a piezoelectric stack responsive to a control signal input, a displacement amplifier operatively associated with the stack, and a high pressure axial valve assembly coupled with the amplifier. A microprocessor control system and energy storage and power amplifier system provide the calibrated output voltage control signal which drives the piezoelectric stack in such a manner as to produce rapidly changing displacements in the stack (as frequent as 10 microseconds) which are subsequently amplified by the displacement amplifier. The valve assembly opens as the piezoelectric stack expands upon application of a step change in voltage, allowing fluid to expand through the valve assembly and create thrust that is substantially equal in duration and directly proportional in amplitude to the control signal.

Abstract: A device and method provide for an accurate output from a unit, such as an oscillator and/or clock providing an output indicative of frequency and/or time. The device includes a processing section having a microprocessor that develops a model characterizing the performance of the device, including establishing predicted accuracy variations, and the model is then used to correct the unit output. An external reference is used to provide a reference input for updating the model, including updating of predicted variations of the unit, by comparison of the reference input with the unit output. The ability of the model to accurately predict the performance of the unit improves as additional updates are carried out, and this allows the interval between the updates to be lengthened and/or the overall accuracy of the device to be improved. The accuracy of the output is thus adaptively optimized in the presence of systematic and random variations.

Abstract: A high speed control apparatus and method utilized in a system having a high pressure fluid supply for producing precisely controlled, amplitude and duration variable thrust are disclosed, the apparatus including a co-fired piezoelectric stack connected with a control signal input, a low-loss mechanical displacement amplifier operatively associated with the stack, and a high pressure spring-loaded axial valve assembly coupled with the amplifier. A microprocessor control system and energy storage and power amplifier system are utilized to provide a calibrated output voltage control signal which drives the piezoelectric stack in such a manner as to produce rapidly changing displacements in the stack (as frequent as 10 microseconds) which are subsequently amplified by the displacement amplifier. The valve assembly is connected with the amplifier and includes a valve core which is normally forced closed upon a valve seat by a compression spring.

Abstract: A high-T.sub.c superconductor contact unit having low interface resistivity is disclosed, as is a method for making the unit. An inert metal is deposited on the surface of the superconductor, which surface is preferably non-degraded, to form a unit with the surface of the superconductor, and where temperatures as high as 500.degree. C. to 700.degree. C. can be tolerated, the unit is oxygen annealed to establish a still lower surface resistivity between the surface of the high-T.sub.c superconductor and the inert metal, including a low surface resistivity of about 10.sup.-10 .OMEGA.-cm.sup.2 at high-T.sub.c superconductor operating temperatures. The superconductor is a metal-oxide superconductor, and may be rare earth, thallium, or bismuth based.