Abstract: An optical cross-connect network provides wavelength routing of optical channels between two arrays of optical fibers carrying WDM signals using interconnected arrays of optical wavelength switches based on combinations of a 1.times.2 wavelength switch architecture. The cross-connect network can be made by interconnecting two arrays of 1.times.4 wavelength switches, each of which is made by combining three 1.times.2 wavelength switches. Each 1.times.2 optical wavelength switch includes a polarization separation element that decomposes and spatially separates the input signal into two orthogonally-polarized beams, and a wavelength filter that decomposes into the beam pair into two pairs of orthogonally-polarized beams that carry a first spectral band at a first polarization and a second spectral band at an orthogonal polarization. A polarization-dependent routing element spatially separates these four beams into four orthogonally-polarized components.

Abstract: A programmable wavelength router having a plurality of cascaded stages where each stage receives one or more optical signals comprising a plurality of wavelength division multiplexed (WDM) channels. Each stage divides the received optical signals into divided optical signals comprising a subset of the channels and spatially positions the divided optical signals in response to a control signal applied to each stage. Preferably each stage divides a received WDM signal into two subsets that are either single channel or WDM signals. A final stage outputs optical signals at desired locations. In this manner, 2.sup.N optical signals in a WDM signal can be spatially separated and permuted using N control signals.

Abstract: An optical power regulator employs a variable optical attenuator having a first birefringent element that spatially separates the input optical beam into two orthogonally-polarized beams. Both beams pass through a polarization modulator (e.g., a liquid crystal material) that rotates their polarizations to an extent determined by the control voltage applied across the polarization modulator. A final birefringent element spatially separates both beams exiting the polarization modulator into two pairs of orthogonally-polarized beams (i.e., two horizontally-polarized and two vertically-polarized components). The thicknesses and optical properties of the birefringent elements are selected so that two of the four beams are combined by the final birefringent element to exit at the output port of the regulator, while the remaining two beams are blocked.

Abstract: An optical routing switch provides polarization-independent and low-crosstalk switching between an optical input port and a plurality of output ports over a wide operating range of temperatures and wavelengths. Optical signals appearing at the input port are spatially decomposed into two orthogonally-polarized beams by a first polarization-dependent routing element (e.g., a birefringent element or polarized beamsplitter). Beyond this point, a network of optical switches are placed along the optical paths of the light beams. Each optical switch includes: (1) a polarization rotator that switchably controls the polarization of the input light beams so that both of the emergent beams are either vertically or horizontally polarized, according to the control state of the device; and (2) a polarization-dependent routing element that spatially routes the light beam pair to provide physical displacement based on their state of polarization.

Abstract: A switchable wavelength router has a first polarization-dependent routing element (e.g., a birefringent element, polarized beamsplitter, or angled polarization separator) that decomposes and spatially separates an incoming WDM optical signal into two orthogonally-polarized beams. A first polarization rotator selectably rotates the polarization of one of the beams to match the polarization of other beam, based on an external control signal. A wavelength filter (e.g., stacked waveplates) provides a polarization-dependent optical transmission function such that the first beam decomposes into third and fourth orthogonal beams, and the second beam decomposes into fifth and sixth orthogonal beams. The third and fifth beams carry a first spectral band at a first polarization and the fourth and sixth beams carry a second spectral band at an orthogonal polarization. A second polarization-dependent routing element spatially separates these four beams into four horizontally polarized and vertically polarized components.

Abstract: A programmable wavelength router having a plurality of cascaded stages where each stage receives one or more optical signals comprising a plurality of wavelength division multiplexed (WDM) channels. Each stage divides the received optical signals into divided optical signals comprising a subset of the channels and spatially positions the divided optical signals in response to a control signal applied to each stage. Preferably each stage divides a received WDM signal into two subsets that are either single channel or WDM signals. A final stage outputs optical signals at desired locations. In this manner, 2.sup.N optical signals in a WDM signal can be spatially separated and permuted using N control signals.

Abstract: This invention provides polarization-independent optical filters that are Fabry-Perot filters. The inventive filters incorporate a phase modulator within the FP cavity and two quarter-wave plates, one on either side of the phase modulator, in the cavity. The quarter-wave plates are perpendicular to each other and oriented at .+-.45.degree. with respect to the optic axis of the phase modulator. A variety of phase modulators including those that incorporate nematic and smectic liquid crystal optical modulators can be employed in these FP filters. The filters of this invention are particularly useful in fiber optic systems and in telecommunications applications at 1550 nm.

Abstract: A system for evaluating one or more biochemical markers for evaluating individual cancer risk, cancer diagnosis and for monitoring therapeutic effectiveness and cancer recurrence, particularly of bladder cancer. The system uses automated quantitative fluorescence image analysis of a cell sample collected from a body organ. Cells are treated with a fixative solution which inhibits crystal formation. Cell images are selected and stored as grey level images for further analysis. Cell images may be corrected for autofluorescence using a novel autofluorescence correction method. A neural net computer may be used to distinguish true-positive images from false-positive images to improve accuracy of cancer risk assessment. Cells having images positive for a marker amy be compared to threshold quantities related to predetermined cancer risk.

Abstract: A system for evaluating one or more biochemical markers for evaluating individual cancer risk, cancer diagnosis and for monitoring therapeutic effectiveness and cancer recurrence, particularly of bladder cancer. The system uses automated quantitative fluorescence image analysis of a cell sample collected from a body organ. Cells are treated with a fixative solution which inhibits crystal formation. Cell images are selected and stored as grey level images for further analysis. Cell images may be corrected for autofluorescence using a novel autofluorescence correction method. A neural net computer may be used to distinguish true-positive images from false-positive images to improve accuracy of cancer risk assessment. Cells having images positive for a marker amy be compared to threshold quantities related to predetermined cancer risk.

Abstract: An ultrasonic imaging system includes a 2D transducer array which transmits ultrasonic energy at an object to be imaged. The echo signals received at the separate transducer elements are weighted to produce limited diffraction beams and the weighted signals are Fourier transformed to produce a 3D k-space data array. A 3D image is produced by performing an inverse fast Fourier transform on the k-space data array.

Abstract: A switchable wavelength router has a first birefringent element that decomposes and spatially separates an incoming WDM optical signal into two orthogonally-polarized beams. A first polarization rotator selectably rotates the polarization of one of the beams to match the polarization of other beam, based on an external control signal. A wavelength filter (e.g., stacked waveplates) provides a polarization-dependent optical transmission function such that the first beam decomposes into third and fourth orthogonal beams, and the second beam decomposes into fifth and sixth orthogonal beams. The third and fifth beams carry a first spectral band at a first polarization and the fourth and sixth beams carry a second spectral band at an orthogonal polarization. A second birefringent element spatially separates these four beams into four horizontally polarized and vertically polarized components.

Abstract: This invention provides analog phase modulators comprising smetic liquid crystal cells wherein the layers are specifically not aligned perpendicular to the cell walls. The layers are either tilted with respect to the substrate or are in a chevron structure. Application of an analog electric field perpendicular to the cell walls bends the molecules in an analog fashion in a plane not parallel to the cell walls and thereby provides analog phase modulation of incident light. Analog phase modulation can not be directly provided by the surface-stabilized smectic liquid crystal cells known in the art, nor can analog tilting of SmC* liquid crystals be achieved. This invention further provides Fabry-Perot devices containing these analog phase modulators within the resonance cavity. The filter of this invention is optimally suited for wavelength-division multiplexing in photonic networks. It has high throughput, large tuning range, high resolution, and high modulation speed.

Abstract: An acoustic transducer produces a limited diffraction beam during the transmit portion of a pulse-echo sequence that has sidelobes extending away from the beam axis in defined sectors. During the receive portion of the pulse-echo sequence a receive aperture for a limited diffraction beam is employed having sidelobes extending away from the beam axis in defined sectors that do not overlap the transmit sidelobes. Both limited diffraction Bessel beams and limited diffraction X waves are employed, and an acoustic transducer producing tenth derivative X waves is described.

Abstract: This invention provides smectic liquid crystal cells with lateral electrodes. The effective change in refractive index with field-induced tilting of the liquid crystal molecules is increased by providing an angle between the direction of propagation of light and the direction of the molecular directors at zero applied field. For homeotropically aligned liquid crystals this is accomplished by inclining the incident light beam at an oblique angle to the device surface. For tilted layer cells the liquid crystal layers are tilted and the light can impinge at normal incidence. This invention further provides Fabry-Perot filters utilizing lateral electrode liquid crystal cells.

Abstract: A polyacetal resin composition which comprises (A) 100 parts by weight of a polyacetal resin, (B) 0.1 to 1.5 parts by weight of at least one kind selected from the group of light stabilizers represented by the following formula (1) ##STR1## wherein two X's are the same or different and each denotes a hydrogen atom or a methyl group, (C) 0.1 to 1.5 parts by weight of an ultraviolet light absorber, (D) 0.1 to 3 parts by weight of polyethylene, (E) 0.1 to 5 parts by weight of polyethylene glycol, and (F) 0.1 to 10 parts by weight of a polymer of a methacrylate ester. This polyacetal resin composition is excellent in weather resistance and molding processability.

Abstract: This invention provides an electro-optic modulator which, in some embodiments, utilizes the linear electro-optic effect in liquid crystal materials. The liquid crystal modulator of this invention comprises a chiral smectic liquid crystal cell with electrodes to supply an electric field in a direction with a nonzero linear electro-optic coefficient, and means to suppress change in the tilt angle and azimuthal angle of the liquid crystal molecular directors. The response time of the linear electro-optic effect modulators of this invention is in the nanosecond range or faster. This modulator can be employed in Fabry-Perot or waveguide devices to provide increased modulation via multiple passes. This invention further provides for prism-coupling of light into or out of the waveguide structure whereby the modulator provides amplitude modulation, tunable filtering, or both.

Abstract: This invention provides a fiber waveguide with a liquid crystal core. The liquid crystals are aligned in layers with molecular directors approximately parallel to each other. An electric field can be applied to the liquid crystal core to provide linear and nonlinear optical modulation. Alone or in combination with polarizers, reflectors, and birefringent elements, the waveguide of this invention provides phase, polarization and intensity modulation, spectral filtering, and second harmonic generation.

Abstract: An ultrasonic transducer for use in medical imaging systems includes a piezoelectric element having an active electrode formed as a series of concentric annular segments. Each segment is separately driven by a transmitter in which the amplitude and phase of the drive signals produce an ultrasonic wave having a pressure profile that approxinmates a zeroth order Bessel function. A nondiffracting beam of ultrasonic waves is produced.