Abstract: A plurality of connecting elements projects from a body's surface. A plurality of indents is defined in the body's surface. Each stem element includes first and second stalks projecting orthogonally from the surface. The first stub includes a pyramidical cap section and at least one generally planar wall. The second stalk is generally parallel to the first stub and spaced apart from the at least one wall, defining a gap therebetween. The second stalk includes a stem projecting from the surface. A lip section extends from a distal end of the stem and protrudes outwardly relative to the stem. An engagement section extends from the lip section. A free end of the engagement section defines a distal end of the second stalk. An outer surface of the engagement section defines a first gradient tapering from the lip section to the distal end of the second stalk.

Abstract: A plurality of connecting elements projects from a body's surface. A plurality of indents is defined in the body's surface. Each stem element includes first and second stalks projecting orthogonally from the surface. The first stub includes a pyramidical cap section and at least one generally planar wall. The second stalk is generally parallel to the first stub and spaced apart from the at least one wall, defining a gap therebetween. The second stalk includes a stem projecting from the surface. A lip section extends from a distal end of the stem and protrudes outwardly relative to the stem. An engagement section extends from the lip section. A free end of the engagement section defines a distal end of the second stalk. An outer surface of the engagement section defines a first gradient tapering from the lip section to the distal end of the second stalk.

Abstract: A plurality of connecting elements projects from a surface of an article. Each connecting element includes a first stalk and second hollow stalk projecting from the surface. The second stalk is generally coaxial with the first stalk and spaced apart from the first stalk defining a radial gap therebetween. The first stalk includes a cap section. The second stalk includes a stem projecting generally orthogonally, at a proximal end thereof, from the surface. A flange section having a first wall thickness extends from a distal end of the stem and has an outer diameter greater than an outer diameter of the stem at the distal end. An engagement section extends from the flange section. A free end of the engagement section having a second wall thickness defines a distal end of the second stalk and has an outer diameter less than the outer diameter of the flange section.

Abstract: An article includes a plurality of stems projecting from a surface thereof. Each stem includes a hollow stalk projecting orthogonally from the surface and a hollow head defined on a distal end of the hollow stalk. The head includes a flange section extending from the distal end of the hollow stalk and having an outer diameter greater than an outer diameter of the hollow stalk at the distal end. A cap section extends from the flange section, defines a distal end of the stem and has a generally convex contour. The cap section has a first wall thickness at the distal end of the stem, a second wall thickness at a junction of the cap section and the flange section and a third wall thickness at a circumferential section intermediate the distal end and the flange section. The third wall thickness is less than the first and second wall thicknesses.

Abstract: A measurement method and apparatus rely upon the coherent optical interference between a reference beam and a diffractionless sensing beam having an optical path length that has been disturbed. The interference pattern can be analyzed to determine a measurement parameter of the disturbance. The diffractionless beam is particularly a Bessel beam. Exemplary optical interferometer types including Mach-Zehnder, Michelson, Sagnac and Fabry-Perot include a Bessel beam generator to generate a diffractionless beam as the sensing optical beam and in some aspects the reference optical beam of the interferometer. The sensing optical beam propagates along a sensing optical beam path in free-space. The reference optical beam path may be a free-space medium or a material medium such as an optical fiber. The sensing optical beam path is subject to a disturbance manifested by the optical interference pattern between the sensing optical beam and the reference optical beam.

Abstract: Embodiments of the invention are directed to a free-space communications system, a signal transmission platform for a free-space communications system, and a method for free-space communications, that advantageously provide or have the potential to provide measurable improvements in free-space communications over a turbulent atmospheric transmission path. A principal feature of all of the embodiments disclosed herein is the generation of a pseudo-non-diffracting communications signal transmission beam, referred to herein as a ‘non-diffracting signal transmission beam’. A realizable embodiment of such a non-diffracting signal transmission beam known in the art is a Bessel beam. A free-space communications system includes a communications signal transmitter platform that ultimately can generate a particularly specified transmission signal waveform, which is a non-diffracting signal transmission beam.

Abstract: A method for mitigating modal dispersion in a multimode optical fiber involves launching a diffractionless optical beam, such as a Bessel beam, into a multimode optical fiber. A fiber optical transmission system includes a multimode optical fiber transmission medium having an input end and an output end, an optical signal transmitter in communication with the input end of the multimode optical fiber medium, means for converting the optical signal into a diffractionless optical signal, means for launching the diffractionless optical signal in the input end of the multimode optical fiber transmission medium, means for outputting the propagated optical signal from an output end of the multimode fiber transmission medium, and a receiver that receives the optical signal from the output means.

Abstract: Surface temperature measurements of the tubes of operating power boilers are facilitated by using ganged and preferably scannable hollow-core sapphire probes to capture infrared radiation emanating from discrete tube surface areas. By selectively overlapping the tube surface areas scanned, the greater diameter of the scanning beam in relation to the tube diameter is compensated for and individual tubes can be assessed for surface temperature. Multiplexing the outputs of many probes to a remote signal processor which also controls the scanning regimens provides systematic automated temperature readings.

Abstract: Temperatures along the surfaces of water tubes in an operating steam boiler are determined by detecting infrared radiation emitted from the tube surfaces in one or more narrow pass-bands founds to be available despite the presence of hot and turbulent flue gases between the sensor and the tube surface to be measured.

Abstract: Bias drift error caused by optical back-reflections of clockwise and counterclockwise rotating beams in an integrated optic fiber-optic gyro and originating at a chip/coil interface are reduced by using a chip architecture designed so that the pathlength over which one of the beams is transmitted before being coupled into a fiber-optic coil and the pathlength over which the other beam is transmitted are different. The difference is provided by bending a waveguide transmitting the one beam, with said bending being enhanced by the application of the Titanium Indiffused Proton Exchange process.

Abstract: The direction and rate of rotation of a closed-loop fiber-optic angular rate sensor is determined by employing acousto-optic modulators in each arm of the sensor and determining the frequency difference between the modulators. Since the modulators operate at a relatively high frequency, frequency measurements to within several hertz are implemented by providing the difference frequency and the sign of the difference frequency via the use of electronic mixers. Since the maximum difference frequency is in the order of a few megahertz, standard counters can thus be used to accurately measure the reduced frequency and hence provide information relating to the direction and rate of rotation.

Abstract: An adjustable fiber optic polarizer (10) comprising tubular member (14) and a bulk polarizer (12) disposed within tubular member (14) and including a two-axes adjusting device (20) disposed in each end of the tubular member (14). Interface device (40) can be positioned in the two-axes adjusting device (20). The two-axes adjusting device (20) supports an interface device (40) which connects the fiber optic to the graded index lens (42). Adjusting device (20) permits two-axes motion of the supported lens (42) with respect to the bulk polarizer (12). The two-axes positioning device (20) can also be rotated with respect to the bulk polarizing device (12) for a maximum optical throughput and polarization extinction ratio.

Abstract: A splice joint is effected between single mode polarization maintaining (SMPM) fibers (31, 32) in a manner so as to maintain polarization of light transmitted through the splice. Mating ends (57, 58) of the respective fibers (31, 32) are aligned and joined with ultraviolet curing epoxy (61). After the ultraviolet curing epoxy (61) is cured, five-minute epoxy (63) is applied over the joint so as to effect mechanical rigidity of the joint. In one arrangement, the five-minute epoxy is reinforced with a sleeve (55).Advantages include the ability to simplify splicing of SMPM fibers, while maintaining polarization characteristics of the fibers.