Abstract: An illustrative downhole sensing system includes a phase-squeezer assembly, an interferometer with a downhole sensor on the sensing path, and a receiver. The phase squeezer assembly provides a phase-squeezed laser beam, preferably with a squeeze parameter greater than 2. Certain embodiments include a pulse generator that gates the phase-squeezed laser beam to form a sequence of phase-squeezed laser pulses, and may further include a compensator that converts the sequence of pulses into a sequence of double pulses with a slight frequency shift between the pulses in each pair. The interferometer conveys a reference portion of the phase-squeezed laser beam along a reference path and a sensing portion of the phase-squeezed laser beam along a sensing path. A downhole sensor along the sensing path provides the sensing portion of the phase-squeezed laser beam with a measurement-parameter dependent phase shift relative to the reference portion of the phase-squeezed laser beam, which is measured by the receiver.

Abstract: The present disclosure provides a mobile machine including a laser diode based lighting system having an integrated package holding at least a gallium and nitrogen containing laser diode and a wavelength conversion member. The gallium and nitrogen containing laser diode is configured to emit a first laser beam with a first peak wavelength. The wavelength conversion member is configured to receive at least partially the first laser beam with the first peak wavelength to excite an emission with a second peak wavelength that is longer than the first peak wavelength and to generate the white light mixed with the second peak wavelength and the first peak wavelength. The mobile machine further includes a light detection and ranging (LIDAR) system configured to generate a second laser beam and manipulate the second laser beam to sense a spatial map of target objects in a remote distance.

Abstract: An interference observation apparatus includes a light source, a splitting beam splitter, a combining beam splitter, a beam splitter, a mirror, a beam splitter, a mirror, a piezo element, a stage, an imaging unit, an image acquisition unit, and a control unit. An interference optical system from the splitting beam splitter to the combining beam splitter forms a Mach-Zehnder interferometer. The mirror freely moves in a direction perpendicular to a reflecting surface of the mirror. The total number of times of respective reflections of first split light and second split light in the interference optical system is an even number.

Abstract: A method of interrogating an absorbing sample includes using a mode-locked laser mode-locked in both a clock-wise (CW) and a counter-clock wise (CCW) direction to generate first and second optical pulses having different repetition rates. One of the first and second optical pulses is directed in a CW direction and the other of the first and second optical pulses is directed in the CCW direction. The first optical pulses are transmitted through the absorbing sample to probe the absorbing sample while the second optical pulses are transmitted through the absorbing sample to act as a local oscillator. An interference pattern produced by interference between the first and second optical pulses is detected after traversing the absorbing sample.

Abstract: The invention teaches a multiple reference optical coherence tomography scanner that provides a subdermal fingerprint scan, covers an area of approximately 16 mm-17 mm×10 mm in less than a second, and fits into a slim profile of less than 6 mm in thickness, thereby fitting within the slim consumer electronics such as the iPhone and similar consumer electronics. Various embodiments are taught.

Abstract: Disclosed is a method for producing an optical fiber coil including the following steps: a. symmetrical winding of an optical fiber around a shaft, the winding forming a pattern including a same number N of layers of each half of the optical fiber, one layer including a set of turns of optical fiber and spaces between adjacent turns, the winding forming a sectored arrangement including a regular stacking area including at least one continuous sealing surface between two layers of adjacent turns, and an overlap area where portions of optical fiber linking different turns cross each other; b. infiltration of a glue through an external surface of the overlap area in such a way that the glue infiltrates into the spaces located between adjacent turns in the regular stacking area.

Abstract: A frequency swept laser source for TEFD-OCT imaging includes an integrated clock subsystem on the optical bench with the laser source. The clock subsystem generates frequency clock signals as the optical signal is tuned over the scan band. Preferably the laser source further includes a cavity extender in its optical cavity between a tunable filter and gain medium to increase an optical distance between the tunable filter and the gain medium in order to control the location of laser intensity pattern noise. The laser also includes a fiber stub that allows for control over the cavity length while also controlling birefringence in the cavity.

Abstract: A fiber-optic gyroscope is disclosed, wherein the fiber-optic gyroscope has counter-propagating light signals in a closed-loop optical path, and where the light signals are characterized by an orthogonality that mitigates optical coupling between them. In some embodiments, the orthogonality is a difference in frequency of the two signals. In some embodiments, the orthogonality is a difference in the polarizations of the two signals. The orthogonality is imparted on the light signals by a non-reciprocal element that is optically coupled with the optical path. In some embodiments, a gain-balancing filter is also included to ensure that the loop gain for each light signal is substantially equal to one. In some embodiments, the light signals are provided by a gain element that is characterized by inhomogeneous broadening.

Abstract: An apparatus includes a liquid-crystal polarization interferometer that causes an optical path delay between a first and a second polarization of input light. The liquid-crystal polarization interferometer includes a liquid-crystal variable retarder that provides a variable retardance in response to a voltage applied across the liquid-crystal cell. First and second polarizers are located on opposing sides of the liquid-crystal cell. The apparatus includes an image sensor that senses interferograms based on output light that passes through the liquid-crystal polarization interferometer. The apparatus includes a color filter that filters one of the input light and the output light. The color filter has a spectral transmission characteristic that passes more light in a blue spectral region that in a red spectral region.

Abstract: Systems and methods for dynamic bias offset operation in RFOGs are provided. In certain embodiments, an RFOG system includes a fiber optic resonator; laser sources that launch first and second optical beams into the fiber optic resonator in opposite directions; a first servo loop configured to lock the first optical beam to a resonance frequency, the first servo loop including a modulator that modulates the first optical beam at a first resonant tracking frequency; a second servo loop configured to lock the second optical beam frequency, on average, to a resonance frequency, the second servo loop including a modulator that modulates the second optical beam at a second resonant tracking frequency, wherein the second optical beam is further modulated by a modulation frequency; and a filter configured to attenuate signals that result from the interference of the first and second optical beams.

Abstract: A method and a system for determining a displacement of an object are provided. The method includes: providing a predetermined modal power distribution characteristic; directing a light onto the object resulting in a reflected light; propagating the reflected light through different propagation modes, receiving a resulting modal power distribution characteristic; and comparing the resulting modal power distribution characteristic with the predetermined modal power distribution characteristic to determine the displacement of the object.

Abstract: The present invention has the advantages of simple structure, low detection cost, high measurement precision, high detection speed, strong practicability, etc. The present invention relates to a novel array photoelectric sensor grating displacement detection system and method. The system includes a parallel light source, an incremental glass grating ruler, photoelectric sensor arrays, a high-speed voltage comparator, a signal processing unit and a displacement display unit, wherein the incremental glass grating ruler is perpendicular to an irradiation direction, of the parallel light source.

Abstract: Methods and related equipment for dynamic on-axis in-situ interferometry where the reference surface is positioned in an vacuum chamber. The systems use a wavelength shifting, or a phase shifting interferometer that allows the freedom to eliminate the need to step the cavity length physically with the reference surface, allowing the reference surface to be placed inside the vacuum chamber.

Abstract: According to various aspects, exemplary embodiments are disclosed of systems and methods for monitoring locomotive wheel size. In an exemplary embodiment, a system generally includes at least one distance measurement device coupled to a locomotive and configured to measure a distance to a rail when a locomotive wheel is positioned on the rail. The system is configured to use the distance to the rail as measured by the at least one distance measurement device to determine a diameter of the locomotive wheel.

Abstract: A metrology system includes a timing estimator, a sensor, and a position estimator. The timing estimator receives a control signal transmitted at a first timing of a first control loop and estimates a second timing at which the control signal is transmitted in a second control loop subsequent to the first control loop. The sensor senses position information of a wafer. The position estimator estimates the position information of the wafer at the estimated second timing based on the sensed position information of the wafer and outputs the estimated position information of the wafer based on a position request signal.

Abstract: A system and methods for quantitative optical phase imaging of a sample. First second replica field of an image field are generated, characterized by a respective optical phase, cross-polarized and shifted in a shift direction transverse to a normal to the surface of the sample. The replica fields are Fourier transformed, the second replica field is retarded by four successive phase shifts, and, after inverse Fourier transforming, the first and second replica fields pass through an analyzer polarizer and superposing the first and second replica fields on a detector array to create four successive detector signals. The four successive detector signals are solved to derive a gradient of the optical phase of the image field, which may be integrated to obtain a quantitative phase image.

Abstract: A fiber-based polarization sensitive optical coherence tomography (PS-OCT) system uses a new polarization diversity detection (PDD) scheme and requires no active polarization modulating components. Retardation of the sample can be determined from amplitudes of arbitrarily-oriented x- and y-components of the reflected light. A hybrid custom 50/50 coupler with single-mode fiber inputs and polarization maintaining (PM) fiber outputs combines light from sample and reference arms of an interferometer. Another embodiment provides a system adapted to provide co-registered autofluorescence-optical coherence tomography (AF-OCT) imaging. AF excitation light is introduced and collected AF light is extracted at a fiber optic rotary joint (FORJ) equipped with an embedded dichroic mirror. A probe tip that uses a clad fiber to supply light to a focusing element provides enhanced OCT and AF performance.

Abstract: An optical fiber includes multiple optical waveguides configured in the fiber. An interferometric measurement system mitigates or compensates for the errors imposed by differences in a shape sensing optical fiber's response to temperature and strain. A 3-D shape and/or position are calculated from a set of distributed strain measurements acquired for a multi-core optical shape sensing fiber that compensates for these non-linear errors using one or more additional cores in the multicore fiber that react differently to temperature changes than the existing cores.

Abstract: Embodiments described herein relate to lens-free imaging. One example embodiment may include a lens-free imaging device for imaging a moving sample. The lens-free imaging device may include a radiation source configured to emit a set of at least two different wavelengths towards the moving sample. The lens-free imaging device is configured to image samples for which a spectral response does not substantially vary for a set of at least two different wavelengths. The lens-free imaging device may also include a line scanner configured to obtain a line scan per wavelength emitted by the radiation source and reflected by, scattered by, or transmitted through the moving sample. The line scanner is configured to regularly obtain a line scan per wavelength. Either the radiation source or the line scanner is configured to isolate data of the at least two different wavelengths.

Abstract: A laser interferometer that includes a laser interferometer, an position sensitive detector detecting an offset of an optical axis of the laser interferometer, a biaxial rotator turning the laser interferometer toward an arbitrary direction, an angle sensor detecting a rotation angle of the biaxial rotator, a retro reflector reflecting reflected light in a direction parallel to incident light, and a controller performing feedback control of the biaxial rotator so as to track the retro reflector based on signals from the position sensitive detector and the angle sensor. The tracking-type laser interferometer starts tracking control when return light from the retro reflector is returned to a detection range of the position sensitive detector, and changes gain for the feedback control in accordance with a behavior for a position of the return light on the position sensitive detector due to the tracking control.