Abstract: A method and apparatus for the inspection of a substrate provides consistent detection of defects such as cracks, differentiates between different types of defects, and, does not excessively heat the substrate. An infrared radiating source produces infrared energy which illuminates the substrate in a uniform manner at an incident angle. An infrared camera collects a portion of the infrared light which is reflected from the substrate. An image is created from the collected light which includes indicia of the defect. The image is examined as the incident angle is varied for changes in the appearance of the indicia.

Abstract: An antenna system comprising a feed array, a subreflector and a main reflector which are oriented to define a front-fed dual reflector antenna geometry. The feed array is comprised of a plurality of separate feeds which are aligned in a predetermined contour. Each feed array is coupled to a feed network which acts to combine the illumination beams of clusters of a preselected number of feeds to produce a plurality of composite illumination beams. Each composite illumination beam is directed to be incident upon a separate predetermined location on the subreflector which directs the composite illumination beams towards the main reflector. Each composite illumination beam is reflected by the main reflector in a preselected direction so that each composite illumination beam forms an antenna beam that impinges a predetermined coverage area on the Earth.

Abstract: An antenna system comprising a feed array, a subreflector and a main reflector which are oriented to define a side-fed dual reflector antenna geometry. The feed array is comprised of a plurality of separate feeds which are aligned on a predetermined contour. Each feed array is coupled to a feed network which acts to combine the illumination beams of clusters of a preselected number of feeds to produce a plurality of composite illumination beams. Each composite illumination beam is directed to be incident upon a separate preselected location on the subreflector which directs the composite illumination beams towards the main reflector. Each composite illumination beam is reflected by the main reflector in a preselected direction so that each composite illumination beam forms an antenna beam that impinges a predetermined coverage area on the Earth.

Abstract: A photodiode for an input light signal comprising an absorption layer having an absorption coefficient which is less than the absorption coefficient of InGaAs when measured at a wavelength of 1.55 &mgr;m. First and a second cladding layer are disposed on opposite sides of the absorption layer leaving exposed a side of the absorption layer. Positively and negatively polarized contact layers are disposed on the first and second cladding layers respectively. The input light signal is directed into the exposed side of the absorption layer and the absorption layer absorbs the input light signal and photo-generates therefrom carriers. The contact layers collect the carriers and generate therefrom photocurrent.

Abstract: An implant patterned superconductive device and a method for indirect implant-patterning of oxide superconducting materials is provided. The method forms a device having an oxide superconducting layer on a substrate, deposits a passivation layer atop the oxide superconducting layer, and implants chemical impurities in a selected portion of the superconducting layer through the passivation layer. This modifies the conductivity of the selected portion of the oxide superconducting layer and electrically isolates the selected portion from the non-selected portion of the oxide superconducting layer. The passivation layer is made of a material less susceptible to implant damage than the oxide superconducting layer to allow inhibition of the oxide superconducting layer while protecting the crystalline structure of the top surface of the oxide superconducting layer and keeping it planarized.

Abstract: A compact delay stage for phase delaying a light signal to provide increased amounts of phase delay to a light signal. A plurality of reflective structures are configured to provide a delay path to the light signal. One of the reflective structures is configured to accept the light signal and direct the light signal between the reflective structures a predetermined selectable number of times until the light signal has completed the delay path thereby translating the light signal into a delay signal. One of the reflective structures is configured to provide egress to the delayed signal to exit the compact delay stage.

Abstract: A method and apparatus for inspection of a substrate and a cover glass covering the substrate provides consistent detection of defects in the substrate such as cracks and cracks in the cover glass free of visual inspection of the substrate and the cover glass. An electromagnetic radiating source produces infrared radiation which illuminates the substrate and cover glass at a predetermined azimuth angle. The azimuth angle is varied such that the substrate and cover glass are illuminated at a plurality of azimuth angles. The substrate and the cover glass reflect portions of the incident electromagnetic radiation. A radiation detector collects portions of the reflected radiation and creates a plurality of images therefrom which include indicia representative of the defect in the substrate and the crack in the cover glass.

Abstract: A method and apparatus for adjusting the location of the back focus of a lens while maintaining the primary focal point location thus eliminating the need to position external components around the back focus location. Instead, the back focus can be positioned around the external components. The shape of the first and second surfaces of the lens are altered to adjust the back focus to a desired location while maintaining the location of the primary focus.

Abstract: A frequency modulation-based optical analog-to-digital converter utilizes a downward-folding, successive approximation approach. A series of stages is utilized to generate bits in the digital signal. In each stage, complementary low and high bandpass filters collectively cover a bandpass frequency range from a low frequency to a high frequency. The high frequency filtered signal from the high bandpass filter is observed to obtain a bit in the digital word. By performing the folding operations in the frequency domain, the converter avoids the difficult task of optical power subtraction, relying instead on frequency down-conversions. The high frequency filtered signal passed by the high bandpass filter is then downconverted and added to the low pass filter signal to generate a modulated signal for the next stage.

Abstract: The invention relates to a method for producing an electrical connection to a high temperature superconductor (HTS) circuit, where a polymer material is applied to the HTS surface covering the circuit contact disposed on one surface of the HTS circuit, a via is created in the polymer material exposing the circuit contact, a diffusion barrier is applied into the via covering the circuit contact; and, a solder bump is applied to the diffusion barrier.

Abstract: A frequency selective medium that is adapted to receive an incident electromagnetic radiation at an angle of incidence of about 45.degree. has two arrays of conductive elements on opposite parallel surfaces (20, 22) of a dielectric substrate. In one embodiment, the conductive elements are cross-dipoles (6) each having a horizontal dipole (10) and a vertical dipole (8) of different lengths and widths. In another embodiment, the conductive elements comprise a plurality of conductive gridded rectangular loops (40). The frequency selective medium allows incident waves that are within a passband of transmit frequencies to transmit through the medium, and reflects waves at frequencies within a stopband adjacent the passband. In other embodiments, meanderline polarizers (28) are added to cross-dipole and gridded rectangular loop frequency selective media to circularly or dual-linearly polarize incident linearly polarized waves.

Abstract: A photodetector having improved responsivity includes first, second and third contact layers and first and second absorption layers. The first and second absorption layers are disposed on opposite sides of the first contact layer. The second contact layer is disposed on the first absorption layer and the third contact layer is disposed on the second absorption layer. The first contact layer has a first polarity. The second and third contact layers have a second polarity which is opposite the first polarity. Preferably, the first and second absorption layers are each made of a material having approximately equivalent electrical characteristics and the second and third contact layers are interconnected. Alternatively, one absorption layer is responsive to a first wavelength and another absorption layer is responsive to a second wavelength.

Abstract: A dual mode horn reflector antenna for providing an antenna pattern having symmetrical beamwidths over a bandwidth of approximately 40%. An input TE.sub.10 rectangular mode signal is provided to the dual mode horn reflector antenna which generates a first TE.sub.11 circular mode signal from the input TE.sub.10 rectangular mode signal. A first TE.sub.10 square mode signal and a first TE.sub.01 square mode signal are generated from the first TE.sub.11 circular mode signal. The first TE.sub.10 square mode signal and the first TE.sub.01 square mode signal are combined generate a resultant signal. The resultant signal is incident upon a reflecting structure which generates an antenna pattern having approximately equivalent beamwidths in perpendicular planes, and reduced sidelobes.

Abstract: The invention relates to a method for producing low cost integrated microwave assemblies, where a photoresist layer is deposited onto a substrate, a portion of the photoresist is selectively removed, a first conductive layer is applied, and, a second portion of the photoresist is removed leaving isolation walls and cavities. Electrical components are placed in the cavities and a first dielectric layer fills the cavities. Vias are created in the first dielectric material exposing the electrical contacts, a second conductive layer is applied into the vias and over the first dielectric material. The second conductive layer is patterned by removing a portion of the second conductive layer creating a signal line pattern in the second conductive layer.

Abstract: A multi-focus reflector antenna for providing a plurality of antenna patterns from a single reflector structure eliminates the need for multiple reflector antennas on a single spacecraft. The multi-focus reflector antenna includes a plurality of at least partially overlapping reflecting structures on a single support structure, each reflecting structure having a focal point and a focal axis. A plurality of RF signals radiate from the focal points, at least one of which passes through at least one of the plurality of reflecting structures and is incident upon another of the plurality of reflecting structures. The plurality of reflecting structures then direct the plurality of RF signals along the plurality of focal axis and generate a plurality of antenna patterns. The multi-focus reflector has applications in communications systems and more particularly, in satellite voice and data communications, and other RF type signals.

Abstract: A frequency selective medium that is adapted to receive an incident electromagnetic radiation at an angle of incidence of about 45.degree. has two arrays of conductive elements on opposite parallel surfaces (20, 22) of a dielectric substrate. In one embodiment, the conductive elements are cross-dipoles (6) each having a horizontal dipole (10) and a vertical dipole (8) of different lengths and widths. In another embodiment, the conductive elements comprise a plurality of conductive gridded rectangular loops (40). The frequency selective medium allows incident waves that are within a passband of transmit frequencies to transmit through the medium, and reflects waves at frequencies within a stopband adjacent the passband. In other embodiments, meanderline polarizers (28) are added to cross-dipole and gridded rectangular loop frequency selective media to circularly or dual-linearly polarize incident linearly polarized waves.