Abstract: An optical position-measuring device includes a measuring graduation having a measuring graduation period and a scanner movable relative to the measuring graduation. The scanner projects a light pattern having alternating bright and dark regions with a light pattern period onto the measuring graduation. The measuring graduation period differs from the light pattern period such that interaction of the light pattern with the measuring graduation produces a vernier pattern having bright regions and dark regions. The measuring graduation is a phase grating having a line-to-space ratio different from 1:1 and a phase shift between lines and spaces selected such that the zeroth diffraction order is suppressed. The position-measuring device is configured such that, at a position at which the zeroth diffraction order of a bright region is suppressed, a higher diffraction order is deflected and impinges on a detector array in a bright region of the vernier pattern.

Abstract: Systems, methods, and devices of the various embodiments enable mitigation of the effects of birefringence in Optical Frequency Domain Reflectometer (OFDR) sensing fiber. Various embodiments enable the measurement of the polarization state of the light in a sensing fiber throughout the entire sensing cable in a highly distributed manner typical of OFDR systems. Various embodiments enable the production of a distributed fiber birefringence measurement throughout the length of an OFDR sensing fiber. Various embodiments may enable OFDR to be 100% polarization diverse, meaning that polarization effects in the fiber optic cables and sensing fiber do not negatively effect measurements. Additionally, the highly distributed measurement of the polarization state and related birefringence in a sensing fiber of the various embodiments may enable new types of measurements such as pressure, twisting, and bending along the sensing fiber.

Abstract: Systems and methods are provided for a microscope-integrated intraoperative scanner system having automated tracking of an instrument tip. A scanning mirror is configured such that a field of view of the OCT system is determined by a position or orientation of the scanning mirror. A drive system is configured to control the scanning mirror. Camera assemblies are configured to determine respective two-dimensional projections of the positions of markers attached to a surgical instrument. A stereo vision system is configured to determine a three-dimensional location of each of the markers from the determined two-dimensional positions. An instrument tracking component is configured to determine a position of a working tip of the surgical instrument according to the determined three-dimensional locations. A drive control is configured to instruct the drive system to adjust the scanner mirror to control the field of view of the OCT system.

Abstract: This invention describes a gyroscope using a fiber coil which is coupled using integrated on-chip 3×3 and 2×2 couplers in coplanar as well as non-coplanar (NCP) configuration along with photodetectors, light sources, and processing electronics using Si, SOI, and InGaAs-on-Si, and other substrates. In one embodiment, a high sensitivity gyroscope using a combination of 2×2 and 3×3 waveguide couplers is described. The signals from three photodetectors can be used to generate feedback signals to produce high sensitivity. Still in another embodiment, usage of multiple quantum well (MQW) waveguides is illustrated. MQW waveguides can be tuned to achieve phase modulation/correction in couplers.

Abstract: A direction-selective interferometric optical filter for spectrometric devices, at least includes an arrangement of two layered one-dimensional photonic structures. Each of the two structures contains a defect layer, and each photonic structure has a dispersion function in the energy momentum space (E, kx, ky), wherein kx and ky are momentum components of transmitted photons of the photonic structures for a defined energy (frequency/wavelength) E in the energy momentum space. Both photonic structures have opposite interfaces which are at a plane-parallel distance from one another. In this case, the dispersion functions of both photonic structures cross or intersect in the energy momentum space and produce a cut set of rays of waves on the surfaces of the dispersion functions at a particular energy, wherein a ray of waves contains waves selectively chosen through the filter at an angle, while other waves are reflected by the filter at other angles.

Abstract: An optical filter element for devices for converting spectral information into location information, uses a connected detector for detecting signals. The element has at least two microresonators, each comprising at least two superposed reflective layer structures of a material layer having a high refractive index and a material layer having a low refractive index in an alternating sequence, and at least one superposed resonance layer arranged between the two superposed reflective layer structures. The filter element comprises at least one transparent plane-parallel substrate for optically decoupling the two microresonators; the first microresonator being located on a first of two opposing surfaces of said substrate, and the second microresonator being located on said substrate on a second surface thereof that lies opposite the first surface.

Abstract: A laboratory system has demonstrated the measurement of three degrees of vibrational freedom simultaneously using a single beam through heterodyne speckle imaging. The random interference pattern generated by the illumination of a rough surface with coherent light can be exploited to extract information about the surface motion. The optical speckle pattern is heterodyne mixed with a coherent reference. The recorded optical data is then processed to extract three dimensions of surface motion. Axial velocity is measured by demodulating the received time-varying intensity of high amplitude pixels. Tilt, a gradient of surface velocity, is calculated by measuring speckle translation following reconstruction of the speckle pattern from the mixed signal.

Abstract: A method for measuring a distance includes modulating the light beam at a first frequency, receiving a second beam by the optical detector to produce a first electrical signal having the first frequency and a first phase; modulating the light beam at a second frequency different than the first frequency; receiving the second beam by the optical detector to produce a second electrical signal having the second frequency and a second. After these steps, the retroreflector is moved while modulating the light beam continuously at the second frequency; and a first distance to the retroreflector is determined based at least in part on a the first and second frequencies and phases.

Abstract: The bias error in a fiber optic system comprising a fiber optic gyroscope can be determined by determining of at least two different values for rotation rate by an evaluation unit of the fiber optic gyroscope for almost constant rotation rate applied to the fiber optic gyroscope and/or can be reduced by a linear combination of the at least two different values for the rotation rate. A fiber optic system that is suitable for carrying out this method comprises besides the fiber optic gyroscope a control device that is configured to control at least one element of the fiber optic gyroscope such that at least two different values for the rotation rate are determined by the evaluation unit of the fiber optic gyroscope for almost constant rotation rate applied to the fiber optic gyroscope.

Abstract: An apparatus (AS) measures positions of marks (202) on a lithographic substrate (W). An illumination arrangement (940, 962, 964) provides off-axis radiation from at least first and second regions. The first and second source regions are diametrically opposite one another with respect to an optical axis (O) and are limited in angular extent. The regions may be small spots selected according to a direction of periodicity of a mark being measured, or larger segments. Radiation at a selected pair of source regions can be generated by supplying radiation at a single source feed position to a self-referencing interferometer. A modified half wave plate is positioned downstream of the interferometer, which can be used in the position measuring apparatus. The modified half wave plate has its fast axis in one part arranged at 45° to the fast axis in another part diametrically opposite.

Abstract: Exemplary apparatus and process can be provided for imaging information associated with at least one portion of a sample. For example, (i) first different wavelengths of at least one first electro-magnetic radiation can be provided within a first wavelength range provided on the portion of the sample so as to determine at least one first transverse location of the portion, and (ii) second different wavelengths of at least one second electro-magnetic radiation within a second wavelength range can be provided on the portion so as to determine at least one second transverse location of the portion. The first and second ranges can east partially overlap on the portion. Further, a relative phase between at least one third electro-magnetic radiation electro-magnetic radiation being returned from the sample and at least one fourth electro-magnetic radiation returned from a reference can be obtained to determine a relative depth location of the portion.

Abstract: Spectral interferometric systems and methods to characterize lateral and angular spatial chirp to optimize intensity localization in spatio-temporally focused ultrafast beams are described. Interference between two spatially sheared beams in an interferometer leads to straight fringes if the wavefronts are curved. To produce reference fringes, one arm relative to another is delayed in order to measure fringe rotation in the spatially resolved spectral interferogram. Utilizing Fourier analysis, frequency-resolved divergence is obtained. In another arrangement, one beam relative to the other is spatially flipped, which allows the frequency-dependent beamlet direction (angular spatial chirp) to be measured. Blocking one beam shows the spatial variation of the beamlet position with frequency (i.e., the lateral spatial chirp).

Abstract: A system for acquiring images by means of heterodyne digital holography comprises an image sensor having at least one photodiode coupled to an oversampling analog-digital converter.

Abstract: A method for characterizing a microfabrication process and the product thereof is described. A substrate having TSV's formed therein is assessed by determining the geometries and positions of the top and bottom ends of a TSV. Individual TSV's as well as the entire pattern of TSV's formed in a substrate may be assessed.

Abstract: The disclosed technology may include systems, methods, and apparatus for optical measurements. A method is provided that includes receiving, by first and second Extrinsic Fabry-Perot Interferometer (EFPI) sensors, respective portions of interrogation light. The first EFPI sensor is responsive to a measurement stimulus and both the first EFPI sensor and the second EFPI sensor are responsive to a common mode stimulus. The method includes detecting a measurement signal and a first common-mode signal responsive to receiving altered interrogation light from the first EFPI sensor, the measurement signal corresponding to the measurement stimulus. The method includes detecting a second common mode signal responsive to receiving altered light from the second EFPI sensor.

Abstract: Certain implementations of the disclosed technology may include Fabry-Perot Interferometer (FPI)-based sensors systems and methods for measuring a desired stimulus. In accordance with an example implementation of the disclosed technology, a method is provided for receiving, by a Fabry-Perot Interferometer (FPI) sensor, first interrogation light having a first wavelength and second interrogation light having a second wavelength. The FPI sensor is configured to alter the received first interrogation light and the second interrogation light responsive to a measurement stimulus. The method includes detecting, by a first optical detector, a measurement signal responsive to receiving the altered first interrogation light and the altered second interrogation light from the FPI sensor, the measurement signal corresponding to the measurement stimulus. The method includes producing a measurement output signal, the measurement output signal representing an intensity of the measurement signal.

Abstract: An integrated imaging spectrometer for hyperspectral imaging (HSI) system is disclosed. The integrated imaging spectrometer features photonic PLCs that include an array of input channel waveguides, one for each pixel of an image scene. Spectral grating filters are positioned along the length of each waveguide to extract the spectral components as the light propagates to the end of the waveguide. The filters route the optical energy to photodetectors and the detected electrical signals are captured by a read out integrated circuit (ROIC). Together the PLC, detectors, and ROIC form an imaging layer. Stacking imaging layers generates a device capable of recording an entire 3D high-resolution spatial/spectral image data cube in real-time.

Abstract: An interferometric measurement method aims at calculating end face surface angle of multi-fiber connector or ferrule taking into account parallelism deviation angles of the connector or ferrule guide holes. The parallelism deviation angles are measured by scanning the side surfaces of guide pins inserted into the guide holes, which is done simultaneously with the end face scanning. Interferometric data from connector or ferrule end face and side surfaces of the guide pins is gathered during one scanning session—either one simultaneous scan or several scans without moving or re-inserting the connector or ferrule.

Abstract: A three-DOF (Degree of Freedom) heterodyne grating interferometer displacement measurement system comprises a dual-frequency laser, a grating interferometer, a measurement grating, receivers and an electronic signal processing component; the grating interferometer comprises a polarizing beam splitter, a reference grating and dioptric elements; the measurement system realizes displacement measurement on the basis of grating diffraction, the optical Doppler Effect and the optical beat frequency principle. Three linear displacements can be output by the system when the grating interferometer and the measurement grating perform a three-DOF linear relative motion. The measurement system can reach sub-nanometer and higher resolution and precision, and can simultaneously measure three linear displacements.

Abstract: Determining information about a degree of freedom of rigid body motion of an encoder scale includes: directing a first beam toward an encoder scale, in which the first beam diffracts from an encoder scale; combining a diffracted component of the first beam with a second beam to form an interfering output beam; monitoring changes in the output beam as a function of a wavelength of the first and second beams; and determining the information about a degree of freedom of rigid body motion of the encoder scale based on changes in the output beam as a function of the wavelength.