338 results about "Reflectometry" patented technology

The present invention discloses simple and yet highly efficient configurations of optical coherence domain reflectometry systems. The combined use of a polarizing beam splitter with one or two polarization manipulator(s) that rotate the returned light wave polarization to an orthogonal direction, enables one to achieve high optical power delivery efficiency as well as fixed or predetermined output polarization state of the interfering light waves reaching a detector or detector array, which is especially beneficial for spectral domain optical coherence tomography. In addition, the system can be made insensitive to polarization fading resulting from the birefringence change in the sample and reference arms. Dispersion matching can also be easily achieved between the sample and the reference arm for high resolution longitudinal scanning.

Apparatus for inspection of a sample includes a radiation source and an array of detector elements arranged to receive radiation from the surface due to irradiation of an area of the surface by the radiation source. The array has a first operative configuration for resolving the received radiation along a first axis perpendicular to the surface, and a second operative configuration for resolving the received radiation along a second axis parallel to the surface. A signal processor processes the signal from the detector array in the two configurations so as to determine a reflectance of the surface as a function of elevation angle relative to the surface and a scattering profile of the surface as a function of azimuthal angle in a plane of the surface.

An apparatus and method for performing optical coherence domain reflectometry. The apparatus preferably includes a single output light source to illuminate a sample with a probe beam and to provide a reference beam. The reference beam is routed into a long arm of an interferometer by a polarizing beamsplitter. A reflected beam is collected from the sample. A 90.degree. double pass polarization rotation element located between the light source and the sample renders the polarizations of the probe beam and reflected beam orthogonal. The polarizing beamsplitter routes the reflected beam into a short arm of the interferometer. The interferometer combines the reference beam and the reflected beam such that coherent interference occurs between the beams. The apparatus ensures that all of the reflected beam contributes to the interference, resulting in a high signal to noise ratio.

An eye examination system is presented that obtains several parameters of the eye. A system according to some embodiments of the present invention include a keratometry system, a low coherence reflectometry system, and a low coherence interferometry system co-coupled to the eye. In some embodiments, the low coherence interferometry system can provide interferometric tomography data. A processor can be coupled to receive data from the keratometry system, the low coherence reflectometry system, and the low coherence interferometry system and calculate at least one parameter of the eye from that data.

A CW lightwave modulated by a continuously reiterated psuedorandom code sequence is launched into an end of a span of ordinary optical fiber cable. Portions of the launched lightwave back propagate to the launch end from a continuum of locations along the span because of innate fiber properties including Rayleigh scattering. This is picked off the launch end and heterodyned producing a r.f. beat signal. The r.f. beat signal is processed by a plurality (which can be thousands) of correlator type pseudonoise code sequence demodulation and phase demodulator units, operated in different time delay relationships to the timing base of the reiterated modulation sequences. These units provide outputs representative of phase variations in respective unique spectral components in the r.f. beat signal caused by acoustic, or other forms of, signals incident to virtual sensors at fiber positions corresponding to the various time delay relationships.

A multisensor probe for continuous real-time tissue identification. The multisensor probe includes a tissue penetrating needle, a plurality of sensors useful in characterizing tissue and a position sensor to measure the depth of the needle into the tissue being diagnosed. The sensors include but are not limited to an optical scattering and absorption spectroscopy sensor, an optical coherence domain reflectometry sensor, an electrical impedance sensor, a temperature sensor, a pO₂ sensor, a chemical sensor and other sensors useful in identifying tissue. The sensors may take the form of a plurality of optical fibers extending through said needle. A retractable sheath may be disposed around the distal section of the needle to protect the needle when not in use. The sheath retracts when the probe is inserted into tissue and the position of the sheath relative to the needle may be measured to determine the needle's depth. Systems and methods for tissue identification are also provided.

Quantum information processing apparatus and methods are described. The apparatus comprises a device for defining a qubit and a reflectometry circuit for reading out a state of the qubit. The device comprises a semiconductor nanowire extending along a first direction having first and second obtuse or acute edges running along the first direction, gate dielectric overlying the first and second edges of the nanowire and a split gate running across a section of the nanowire in a second, transverse direction, the split gate comprising first and second gates overlying the first and second edges respectively. The reflectometry circuit comprises a resonator coupled to the first or second gate.

Described are techniques used in a wire diagnostics system to detect events, such as defects, that may occur within a wire or cable under test. An incident voltage signal is sent out on the wire and a measured voltage signal is obtained which includes the incident voltage and the reflected voltage. Compensation processing is performed on the measured waveform to remove unwanted reflective components. Additionally, the waveform is then subject to attenuation processing and event detection processing. Detected events, such as defects, are classified and output as results. Events are classified by parametric classification using a library of known events or faults. The library of known events or faults is previously generated using empirical analysis and modeling techniques. Additionally, joint time-frequency domain reflectometry (TFDR) techniques are described for event identification and classification for a wire under test.

A frequency domain reflectometer that is in electrical communication with a cable under test in order to determine cable characteristics including cable length and load characteristics such as capacitance, inductance, resistance, impedance (which is characterized as an open or short circuit condition), and the location of an open or short circuit, wherein the FDR cable testing is performed in-situ when the system is installed at the time of installation of the cable to thereby enable testing of cable without having to remove it and risk damage, wherein FDR cable testing is performed passively so as not to interfere with normal operation of the cable even if the FDR cable testing system should fail, wherein a system is taught that can detect faults that are difficult to detect out of an operating environment, and wherein FDR cable testing is performed to detect cable fray conditions, wherein the cable may be grounded or coupled to air.

A spectroscopy system is provided which is optimized for operation in the VUV region and capable of performing well in the DUV-NIR region. Additionally, the system incorporates an optical module which presents selectable sources and detectors optimized for use in the VUV and DUV-NIR. As well, the optical module provides common delivery and collection optics to enable measurements in both spectral regions to be collected using similar spot properties. The module also provides a means of quickly referencing measured data so as to ensure that highly repeatable results are achieved. The module further provides a controlled environment between the VUV source, sample chamber and VUV detector which acts to limit in a repeatable manner the absorption of VUV photons. The use of broad band data sets which encompass VUV wavelengths, in addition to the DUV-NIR wavelengths enables a greater variety of materials to be meaningfully characterized. Array based detection instrumentation may be exploited to permit the simultaneous collection of larger wavelength regions.

An apparatus and method for high-resolution reflectometry that operates simultaneously in both the time and frequency domains, utilizing time-frequency signal analysis and a chirp signal multiplied by a Gaussian time envelope. The Gaussian envelope provides time localization, while the chirp allows one to excite the system under test with a swept sinewave covering a frequency band of interest. High resolution in detection of the reflected signal is provided by a time-frequency cross correlation function. The high-accuracy localization of faults in a wire/cable can be achieved by measurement of time delay offset obtained from the frequency offset of the reflected signal. The apparatus enables one to execute an automated diagnostic procedure of a wire/cable under test by control of peripheral devices.

An interferometer system includes an optical radiation source, an optical circulator connected between the optical radiation source and a sample location for transmitting optical radiation from the optical radiation source to the sample location, an output of the optical circulator connected to direct optical radiation to an optical detector. Various embodiments of such a system are possible. A method of performing OCDR or OCT imaging of a sample which involves the steps of: (a) producing low coherence optical radiation; (b) directing at least some of the low coherence optical radiation through an optical circulator to the sample; (c) reflecting at least some of the low coherence optical radiation off of the sample; and (d) detecting at least some of the reflected low coherence optical radiation and producing an electrical signal corresponding thereto.

A thin film analysis system includes multi-technique analysis capability. Grazing incidence x-ray reflectometry (GXR) can be combined with x-ray fluorescence (XRF) using wavelength-dispersive x-ray spectrometry (WDX) detectors to obtain accurate thickness measurements with GXR and high-resolution composition measurements with XRF using WDX detectors. A single x-ray beam can simultaneously provide the reflected x-rays for GXR and excite the thin film to generate characteristic x-rays for XRF. XRF can be combined with electron microprobe analysis (EMP), enabling XRF for thicker films while allowing the use of the faster EMP for thinner films. The same x-ray detector(s) can be used for both XRF and EMP to minimize component count. EMP can be combined with GXR to obtain rapid composition analysis and accurate thickness measurements, with the two techniques performed simultaneously to maximize throughput.