Abstract: Chromatic dispersion in an optical cable is measured by applying to the cable a signal that rapidly switches between a wavelength generated by a tunable optical source and a different wavelength generated by a reference source. The two sources are modulated in such a way that a delay line phase detection scheme at the far end of the cable can accurately measure relative delay between the tunable source and the reference source. The chromatic dispersion is determined by measuring the relative delay between the two sources for several different wavelengths of the tunable source.

Abstract: The in-fiber safety interlock system includes a high power (Class IV) laser interlocked to an OTDR. A plurality of WDM data signals are transmitted over the fiber system, including a terminal portion and an extended portion. A control circuit is connected to the laser and the OTDR. The OTDR monitors the integrity of the fiber system, including both the terminal portion and the extended portion. If the OTDR detects a fault in the optical transmission path, the OTDR and the control circuit operate to automatically disable or shut down the laser.

Abstract: An OTDR provides both in-service and out-of-service measurement information for an optical transmission system with multiple repeaters. The repeaters include an optical high-loss loop back (HLLB) path and an OTDR path. The OTDR is coupled to the input lines of the optical transmission system via an optical coupler so that both traffic signals and test signals from the OTDR can be transmitted simultaneously. When the OTDR is providing in-service measurement information, test signals in the form of side-tone pulses are transmitted on the transmission system. The wavelengths of the test signals are sufficiently offset from the wavelength of the traffic signal so there is minimal interference between them. The level of the test signals is low relative to the traffic signal to also minimize interference. The OTDR filters out the traffic signal from the returned signal. The HLLB path through the amplifier pairs of each repeater is distinguishable in the filtered returned signal.

Abstract: A multioscillator ring laser gyro having a Faraday Cell with an optical wedge in one of its branches. Variations in the MCDL of the optical wedge with temperature are reduced to substantially zero. The internally specularly reflected and backscattered beams from said primary beam have path lengths such that the internally double-bounced reflected and scattered beams of each mode have path lengths wherein the differences between the mode directions are adjusted in a particular manner to reduce cyclic variations with temperature in MCDL substantially to zero.

Abstract: A template-type calorimeter comprising a light-transparent substrate having a diffraction grating on a surface thereof, the diffraction grating being operative to diffract light incident thereon from a spaced-apart aperture into its constituent spectral components. A template is provided on a surface of the substrate and arranged to receive the diffracted spectral components. The template has formed thereon at least three spatial filters, each for selectively transmitting diffracted spectral components in accordance with respective ones of the desired color-matching functions such as the CIE x(.lambda.), y(.lambda.), z(.lambda.) or r(.lambda.), g(.lambda.), b(.lambda.) color-matching functions. The diffraction grating and the template may be mounted on opposite sides of the substrate, or they may be mounted in a laterally spaced-apart relationship on the same side of the substrate, in which case the opposite side of the substrate is coated with a reflective material.

Abstract: Embodiments of the present invention feature devices and methods for analyzing the absorbance spectra of a sample, and a method of making such device. The device comprises a housing having an exterior surface and an interior surface. The interior surface defines a chamber having an input opening and an exit opening defined by rims. The input opening has a first geometric shape and the exit opening has a second geometric shape. Any point about the rim at the input end can be connected by a straight line to any point on the rim of the exit end. The interior surface end of the chamber corresponds to the sum of these lines from the rim of the input opening, to the rim of the exit opening.

Abstract: A method for on-line analysis of polycyclic aromatic hydrocarbons (PAH) in aerosols. The aerosols are collected on non-fluorescing filter paper, excited to fluorescence and imaged spectrally. The images are compared with spectra in a database to determine and quantify the PAH species present. The scope of the invention is broader than fluorescence, and includes excitation analysis of particulate matter generally.

Abstract: A lighting control apparatus for illuminating a moving variable-speed web for inspection with a camera is provided. The apparatus is comprised of a detecting device for detecting the positioning of the web; a lighting device, aligned with the camera, for emitting a light to illuminate the web; a calculating device for calculating the speed of the web; and a control device which controls the emission of light by the lighting device as a function of the speed of the web.

Abstract: In a method of measuring on an optical fibre (2), a pulse is launched into the fibre, and the temporal course (8, 9) of the echo of this pulse is measured. Then, a signal level representing the background noise present in the fibre is subtracted in a subsequent signal processing of the echo signal. The signal level representing the present background noise is calculated on the basis of the instantaneous value (20) of the background noise which it assumes during the measurement of the echo signal. In a first embodiment the background noise is measured at a wavelength different from the wavelength of the emitted pulse. In a second embodiment wherein several successive pulses (25, 26) are launched into the fibre, optical power (27) is launched into the fibre at a wavelength other than the pulse wavelength during the intervals between said pulses.

Abstract: An optical scatterometer system enables analysis of a sample material at various wavelengths without rotating or otherwise moving the sample material.

Abstract: A light source portion having an acousto-optic element produces a laser beam of two light components having a frequency difference .DELTA.w and having registered polarization directions. The laser beam is subsequently divided by a half mirror. One of the divided laser beams is detected by a photoelectric detector as reference light, and a corresponding signal is applied to a synchronism detector. The other laser beam is projected by a scanning optical system to the surface of, e.g., an original to be examined to scan the same. At the position on the surface irradiated by the scanning light spot, the laser beam is modulated at a beat frequency .DELTA.w on the basis of optical heterodyne interference. A synchronism detector detects a signal corresponding to the scattered light from a particle or defect on the surface being examined, in synchronism with the frequency of the reference light, whereby the particle or defect can be detected with a good signal-to-noise ratio.

Abstract: A test method and system for the testing of fiber optic connectors in a fiber optic system while the system is operational without external test equipment. An input signal is applied to one end of a fiber optic path comprising a plurality of connections, which results in an output signal. The input signal has known characteristics (e.g., a training pulse) over the fiber optic path. The output signal, which is generated in response to the input signal, is converted from a time domain expression to a frequency domain expression using, for example, Fourier transform analysis. Then, the frequency domain expression of the output signal is combined with a frequency domain expression of the input signal to provide a waveform from which the location of each connector and its relative level of performance can be determined. Advantageously, the method and system do not require disassembly of the fiber optic path.

Abstract: A spectroanalytical system includes entrance aperture defining structure for receiving radiation to be analyzed along a first path; dispersion structure in the first path for spatially dispersing the radiation as a function of wavelength; exit aperture structure defining a non-elongate aperture for receiving radiation from the dispersion structure; detector aperture structure coupled to the exit aperture structure for detecting selected wavelengths of the dispersion radiation; and wedge-like conditioner structure disposed between the first path and between the dispersion structure and the entrance and exit aperture structures.

Abstract: A method for providing an optical fiber coil having reduced bias vibration and bias temperature-ramp sensitivity by controlling and adjusting coil geometrical factors including the coil potted length, the adhesive layer thickness, the number of turns per layer, the number of layers and the way the winding is terminated. The windings may be terminated to form the coil as a complete quadrupole, a diapole, an incomplete quadrupole or an incomplete diapole. By adjusting geometrical factors of the coil design, a coil for which the residual net Shupe bias is negligible is obtained.

Abstract: An illumination system (20) and method for use with an optical web inspection assembly (21) to identify surface defects on a moving material web (25). The illumination system (20) includes an elongated light source (26) having an elongated aperture (46) adapted to transmit a substantially continuous elongated strip of non-collimated light therefrom generally in an entrance direction. An elongated light pipe device (32) is provided having an elongated entrance end (33) and an opposite elongated exit end (36) wherein the entrance end (33) is positioned longitudinally adjacent the light source aperture (46) and configured to substantially receive the strip of light therethrough in the entrance direction. The light pipe (32) includes a smoothly curved interior wall (37) extending from the entrance end (33) to the exit end (36), and defines an optical path configured to reflect and transmit substantially all the light received from the entrance end to the exit end (36).

Abstract: A method for detecting misalignment of initially-aligned fiber filaments in a composite. An optical fiber is placed among the fiber filaments in the composite, light is directed into the optical fiber, the intensity of the light in the optical fiber is measured during subsequent composite processing, and attenuation in such light intensity is ascertained which indicates such misalignment (e.g., wrinkling, bending, buckling, porosity, delamination and the like) is being detected during such processing. In another preferred method, before-processing and after-processing x-ray images are taken of an x-ray-attenuating fiber which has been placed among x-ray-transparent fiber filaments in a composite.

Abstract: Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants.

Abstract: A method and apparatus for evaluating an oxygen concentration in a semiconductor silicon single crystal highly doped with boron at a low cost with a high sensitivity and high reproducibility. The single crystal, which is doped with boron of a high concentration of 10.sup.17 atoms/cm.sup.3 or higher, is irradiated with a light having a greater energy than that of bandgap of the semiconductor silicon while holding the single crystal at a temperature of room temperature to 50 K and photoluminescence intensities in the vicinity of a photon energy of 0.96 eV of a photoluminescence spectrum emitted from the single crystal under the above irradiation are measured to evaluate an oxygen concentration in the single crystal.

Abstract: A non-contact spectroscopy system includes scanning head structure with transmitting optics for focusing radiation onto the surface of material to be analyzed, and receiving optics for collecting radiation reflected from the surface of the material and directing the reflected radiation onto optic fiber structure for transmission to spectroscopic analyzer structure.

Abstract: A sensor device for detecting a wetting condition on a windshield where radiation emitted by a radiation transmitter is coupled with the windshield by a coupling element with a beam acceptance surface designed as focusing lens and where, following at least one total reflection from the windshield via a decoupling element which has a beam emission surface that is also a focusing lens. The radiation is decoupled to a radiation receiver and the axial transmitter radiation is totally reflected on a level first limiting surface, and the radiation acceptance surface has a spherical shape. The radiation transmitter is arranged such that the diverging transmitter radiation is essentially focused axis-parallel toward the first limiting surface and that the dimensions of the first limiting surface are at least big enough so that it detects the complete parallel-focused beam of rays.