Abstract: An array of n-wavelength vertical cavity surface emitting lasers (VCSELs) can be grown with precise and repeatable wavelength control. First, a foundation VCSEL structure is grown on a substrate. Next, n-paired layers of AlGaAs and InGaP are grown, where n is the desired number of different wavelengths. Next, one of the n regions is masked and etched. The steps of masking and etching are repeated until all n regions are etched. Finally, the upper VCSEL structure is grown.

Abstract: This invention provides a simple yet robust solution to the phase-locked loop frequency acquisition problem in clock and data recovery circuits by using a frequency detector with a deadband, which is constructed in part with an oversampling rotational frequency detector.

Abstract: Methods for the fabrication of TS LED chips with improved light extraction and optics, particularly increased top surface emission, and the TS LEDs so fabricated are described. Non-absorbing DBRs within the chip permit the fabrication of the LEDs. The transparent DBRs redirect light away from absorbing regions such as contacts within the chip, increasing the light extraction efficiency of the LED. The non-absorbing DBRs can also redirect light toward the top surface of the chip, improving the amount of top surface emission and the on-axis intensity of the packaged LED. These benefits are accomplished with optically non-absorbing layers, maintaining the advantages of a TS LED, which advantages include .about.6 light escape cones, and improved multiple pass light extraction.

Abstract: The quasi-absolute encoder module determines absolute position within one mechanical rotation. The encoder module includes a three channel position encoder and detection circuitry that includes a read-only memory (ROM). There are three channels: A, B, and I. Channels A and B have four periods and channel B is offset from channel A by 90.degree. in phase. Channel I has a unique sequence. The address generated by sampling this unique sequence corresponds to an address in ROM. The address indicates the position of the rotating shaft on which the code wheel is attached.

Abstract: A method for initializing a distributed measurement and control system that establishes communication bindings based on context parameters measured or acquired by the nodes.

Abstract: A compact and energy efficient projection display can be made by starting with relatively pure red, green, and blue light sources. The output beams of the colored light sources are received by at least one spatial light modulator. The modulated output beams are collimated and combined. A projection lens receives the collimated and combined output beams and directs them towards a projection screen. All of the above may be contained in a housing to provide a compact and lightweight projection display.

Abstract: A conductive shield is formed around a fiber-optic connector. The shield includes a compressible means that encircles the perimeter of the connector. When the connector is inserted, the compressible means electrically contact the chassis to prevent emissions through panel openings required by fiber-optic transceivers.

Abstract: The quasi-absolute encoder module determines absolute position within one mechanical rotation. The encoder module includes a three channel position encoder and detection circuitry that includes a read-only memory (ROM). There are three channels: A, B, and I. Channels A and B have four periods and channel B is offset from channel A by 90.degree. in phase. Channel I has a unique sequence. The address generated by sampling this unique sequence corresponds to an address in ROM. The address indicates the position of the rotating shaft on which the codewheel is attached.

Abstract: Light emitting diodes with highly reflective contacts and methods for fabricating them are described. In a first preferred embodiment of the present invention, LEDs with reflective contacts are formed using a laser to create small alloyed dots in a highly reflective metal evaporated on the top and bottom surface of the LED chip. Using this technique, most of the bottom surface remains highly reflective, and only those portions of the bottom surface where the laser struck become absorbing. Typically, only 1% of the bottom surface is formed into contacts, leaving 99% of the bottom surface to serve as a reflecting surface. The 1% of the surface, however, provides an adequate low resistance ohmic contact. LEDs fabricated with this technique allow photons to bounce off the rear surface more than 20 times before there is a 50% chance of absorption.

Abstract: A x-y array of light emitting diodes has insert molded leadframes to minimize manufacturing costs during assembly.

Abstract: The method builds upon the highly repeatable properties of commercial optical fiber, and using commercial fiber for the waveguides in a fabric of optical switches. The method describes assembly of the fabric, locating the intersections, and a structure for placing the mating resistor.

Abstract: A harmonic imaging transducer is a structure of two mechanically coupled piezoelectric layers. This two-layer piezoelectric structure may vibrate either in a symmetric mode, wherein the two layers are expanding and contracting in unison, or in an anti-symmetric mode, wherein one layer is contracting while the other is expanding. Symmetric mode vibrations result in first harmonic operation, while anti-symmetric mode vibrations result in second harmonic operation.

Abstract: A color image editing system and method uses sensor responses in an image capture device to estimate and separate illuminant and surface reflectance in a scene. The system uses the estimated surface reflectances, along with a desired illuminant SPD, to calculate the corresponding XYZ values. To render the images on an imaging device, the XYZ values are converted into device-dependent display or printer values. The image data may be manipulated in a manner that is intuitive to humans, such as correcting the image data according to changes in lighting and surface color.An image capture device, such as a scanner or digital camera, represents a scene as image data that is resolved as device-dependent channels, such as RGB. For each channel, the spectral reflectances of the surfaces within the scene are described reflectance functions that are independnt of the lighting function that describes the illuminant spectral power distribution (SPD).

Abstract: This method relates to the fabrication of semiconductor light-emitting devices having at least one ordered textured interface. Controlled interface texturing with an ordered pattern is provided on any or all interfaces of such a device to enhance light extraction from these interfaces and thus improve the performance of the device.Ordered interface texturing offers an improvement in light extraction by increasing the transmission of total optical power from the device into the ambient. This improvement is possible because ordered interface texturing can provide: 1) a reduction in Fresnel losses at the interface between the device and the ambient and, 2) a change or increase in the angular bandwidth of light which may transmit power into the ambient. This latter effect may be thought of a change or increase in the escape cone at an interface. Both effects can result in an overall increase in total light extraction efficiency for the LED.

Abstract: The signal-to-noise ratio of the correction signal used for second harmonic interferometry is improved in two ways. First, an optical amplifier, tuned to the second harmonic frequency, is positioned in the optical path. Second, a doubling stage is positioned internal to the correction laser.

Abstract: Ultrasound energy has been observed to rapidly destroy a large quantity of microbubbles. The duration and intensity of the contrast effect is greatly diminished by conventional imaging frame rates and power levels. Altering the imaging sequence by strategically shooting ultrasound image frames at various transmit powers and reducing the number of transmit lines per frame allows for enhancement of the contrast effect (increasing maximum intensity and duration).

Abstract: A MR compatible monitoring system has a fiber optic data link between the patient monitor and the control room display/keyboard in a magnetic resonance imaging suite to allow for continuous monitoring of a patient's vital signs and provides critical care patients with the same diagnostic options as stable patients. The patient monitor is mounted on the far end of a magnetic resonance compatible patient transporter. The patient transporter sends video data and receives control data from the control room. During the imaging, the patient monitor is located within the magnet room. Magnetic resonance imaging systems are very sensitive to radio frequency interference (RFI) from other equipment and may produce image artifacts because of this interference. Using a fiber optic data link between the patient monitor near the magnet and the control room will minimize the potential RFI.

Abstract: The ideal source for air-turbulence-corrected distance-measuring interferometry is a single laser that generate overlapping beams at two widely separated wavelengths .lambda..sub.1 and .lambda..sub.2. At least one of the wavelengths, as well as the wavelength ratio, must be known to high degrees of accuracy. Furthermore, at each wavelength, the Iaser should produce a pair of orthogonally polarized frequencies with a frequency splitting that is adjustable over the range of approximately 0.5 MHz to 20 MHz to facilitate AC interferemetric distance measurements with a variety of measurement-mirror velocities.

Abstract: N-type doping in III-V-nitride semiconductor compounds, i.e. GaN-based compounds such as GaN, AlGaN, AlInN, InGaN, or AlGaInN, can be optimized to improve N-contact electrical resistance, carrier injection, forward voltage, and recombination characteristics without inducing cracking of the device layers. The N-type layer is constructed of sub-layers such that an N-type sub-layer is provided for each desired characteristic or property. The thickness of each sub-layer is carefully selected to avoid material cracking: the higher the required doping, the smaller the corresponding thickness. In illustration, the buffer layer of a light emitting device (LED) has three sub-layers. The first sub-layer is lightly doped to avoid cracking and is grown to the desired thickness for good material quality. The second sub-layer is heavily doped to provide good N-contact and electrical resistivity characteristics and is kept correspondingly as thin as necessary to avoid material cracking.

Abstract: An improved tri-state output buffer having an emitter-follower output stage clamps the reverse-bias voltage across the base-emitter path of an emitter-follower to limit the output leakage current and thereby extending the operating life of an integrated circuit (IC). A current sensitive voltage device such as a bipolar transistor or diode clamps the reverse-bias voltage of the base-emitter path. Voltage clamping prevents the bipolar transistors from activating while the buffer is disabled. The output leakage current that occurs when the junction is forward biased is minimized. This results in low output load capacitance that improves the propagation delay particularly when multiple buffers are used.