Abstract: Dithering mechanism and method for eliminating the effects of zero-rate bias in a rate sensor or gyroscope. Both continuously moving and indexing embodiments are disclosed. The mechanism includes a first part mounted in a fixed position centered about a dither axis perpendicular to the input axis of the gyroscope, a second part disposed coaxially of the first part and affixed to the sensing element of the gyroscope, and a plurality of piezoelectrically driven quartz flexure beams extending radially between the first and second parts for dithering the second part about the dither axis. In some embodiments, the dithering mechanism is formed separately from and affixed to the sensing element of the gyroscope, and in others it is formed integrally with the sensing element.

Abstract: A measurement method for measuring a position of an aperture stop in an optical system includes the steps of measuring a light intensity distribution of light that passes the aperture stop, at a position that is optically conjugate with a pupil position in the optical system, and determining a position of the aperture stop in the optical system based on a diffraction fringe of the light intensity distribution measured by the measuring step.

Abstract: A pressure measurement system and method are described. The system uses a tunable laser and a Fabry-Perot sensor with integrated transducer. A detector senses the light modulated by the Fabry-Perot sensor. A signal conditioner, which can be located up to 15 km away, then uses the detector signal to determine the displacement of the diaphragm, which is indicative of pressure exerted against the diaphragm. Use of a temperature sensor to generate a signal, fed to the signal conditioner, to compensate for temperature is also contemplated.

Abstract: An fiber-optic interferometric rotation sensor device has a laser source combined with an optical fiber. These are configured to cause interference between a beam from the laser source and a beam coming from the optical fiber. The laser source includes an optical cavity having a gain lasing medium. The sensor device includes, along the path of the beam output by the laser cavity, a beam splitter device associated with a mirror, wherein the beam split off from the beam output by the laser cavity is sent into one of the ends of the optical fiber and directed from the other end toward the gain lasing medium to form a nonlinear mirror. The splitter device is followed by a detector.

Abstract: An apparatus for detecting rotation and a method for constructing the apparatus are provided. The apparatus comprises an optical fiber having a hollow passageway therethrough, a laser medium within the hollow passageway and interconnecting the first and second portions of the hollow passageway, and first and second electrodes contacting the laser medium such that when a voltage is applied across the first and second electrodes, the laser medium is excited such that the laser medium emits laser light through the hollow passageway.

Abstract: An improved lithographic interferometer system, is presented herein. The lithographic interferometer system comprises a beam generating mechanism, mirrors which reflect those beams, and detection devices for detecting an interference pattern of overlapping reflected beams. The beam generating mechanism comprises a beam-splitter, which splits the beams into reference beams and measuring beams, a reference mirror that provides a plane mirror interferometer, and a reflective surface that emits at least one reference beam used in a differential plane mirror interferometer.

Abstract: An optical interferometer (100) includes a first optical interferometer (200) disposed on a front surface side of a workpiece (W) and a second optical interferometer (300) disposed on a rear surface side of the workpiece (W). The first optical interferometer (200) and the second optical interferometer (300) each include a light emitting section (210, 310), a wire grid (220, 320) and an interference fringe sensor (230, 330). Wire alignment directions of the wire grid (220) of the first optical interferometer (200) and the wire grid (320) of the second optical interferometer (300) are orthogonal to each other. When no workpiece (W) is set, the wire grid (220) of the first optical interferometer (200) reflects light from the second optical interferometer (300) to generate object light and the wire grid (320) of the second optical interferometer (300) reflects light from the first optical interferometer (200) to generate object light.

Abstract: A diffractive interferometric optical device is provided for measuring spectral properties of light. The device includes means for coupling in a single spatial mode of an incoming light field to be examined, means for splitting the single spatial mode of incoming light field into at least two partial fields, means for changing one of a shape or a direction of propagation of the wavefront of at least one of the at least two partial fields in dependence on the wavelength and means for generating an interference pattern superimposing the at least two partial fields. The device further comprises detection means to record and evaluate the interference pattern at a plurality of discrete spatial positions in order to derive spectral properties of the incoming light field.

Abstract: Disclosed is a method and apparatus for inspecting defects of patterns of a sample at high speed and with high sensitivity while damage of the sample arising from high-power pulsed light is reduced. Light emitted from a pulsed laser light source is transmitted through a pseudo continuous-wave forming optical system having an optical system capable of reducing energy per pulse and yet maintaining the entire amount of light of the pulsed light, a beam formation optical system, and a coherence reduction optical system, and a beam deflected by a deformation illumination optical system is made to reflect on a PBS to be irradiated on a wafer. The apparatus is configured so that the diffracted light from the wafer is focused by an objective lens, transmitted through light modulation units, focused to form a plurality of images on a plurality of image sensors in a visual-field divided parallel detection unit 12, and then defects are detected by a signal processing unit.

Abstract: A passive optical system substantially simultaneously separates light received at an optical input into three or more output light beams on optical outputs. The output light beams may have intensities that are proportional to intensities of optical projections of the received light onto three or more basis vectors of a tetrahedral basis set of a Stokes space. The system includes either multiple partial polarization splitters or multiple optical interferometers.

Abstract: Methods and apparatus are provided for determining the rotational rate of an optical gyro. An optical gyro comprises at least one substrate, a multi-frequency light source (MFLS) mounted on the substrate, and a resonator coupled to the MFLS. The MFLS is configured to produce a first light beam having a first frequency and a second light beam having a second frequency and phase locked with the first light beam. The resonator comprises an optical fiber coil having a hollow core. The resonator is configured to circulate a portion of each of the first and second light beams through the hollow core. The portion of the first light beam propagates in a first counter-propagating direction, and the portion of the second light beam propagates in a second counter-propagating direction. A measured difference between the first and second frequencies indicates a frequency shift proportional to the rotation rate of the optical gyro.

Abstract: A measuring apparatus and method which is sensitive to rotational but not translational or vibrational movement. The magnitude of an applied rotational force is determined based upon interference patterns created from light reflected from an interferometric prism positioned to rotate in response to an applied rotational force.

Abstract: A spectrometer for use with a desired wavelength range includes an array of filters. Each filter outputs at least two non-contiguous wavelength peaks within the desired wavelength range. The array of filters is spectrally diverse over the desired wavelength range, and each filter in the array of filters outputs a spectrum of a first resolution. An array of detectors has a detector for receiving an output of a corresponding filter. A processor receives signals from each detector, and outputs a reconstructed spectrum having a second resolution, the second resolution being higher than any of the first resolution of each filter.

Abstract: An inspection apparatus is disclosed having an radiation system configured to provide an radiation beam, a beamnsplitter configured to create, from the radiation beam, a first illumination beam and a second illumination beam directed to a planar reference part of a sample and a patterned part of the sample, respectively, and a beam detector configured to detect a detection beam, the detection beam comprising a recombination of radiation scattered from the planar reference part and the patterned part.

Abstract: According to one aspect of the present invention, a method for calibrating a fiber optic gyroscope is provided. A method is provided for calibrating a fiber optic gyroscope. First and second portions of light from a first light source are propagated through a fiber optic line in respective first and second directions. A first voltage that causes a predetermined phase shift between the first and second portions of the light from the first light source is calculated. First and second portions of light from a second light source are propagated through the fiber optic line in the respective first and second directions. A second voltage that causes the predetermined phase shift between the first and second portions of the light from the second light is calculated. A difference between the first voltage and the second voltage is then calculated.

Abstract: A system for probing a DUT is provided, the system comprising a tunable or CW laser source, a modulator for modulating the output of the laser source, a beam optics designed to point a probing beam at a designated location on the DUT, optical detector for detecting the reflected beam, and collection and signal processing electronics. The system deciphers perturbations in the reflected beam by detecting beat frequency between operation frequency of the DUT and frequency of the modulation. In an alternative embodiment, the laser is CW and the modulation is applied to the optical detector.

Abstract: A method and apparatus for performing refractive index, birefringence and optical activity measurements of a material such as a solid, liquid, gas or thin film. The apparatus has an optical ring-resonator with a closed optical path that constitutes a cavity. A sample is introduced into the optical path of the resonator such that the light in the resonator is transmitted through the sample and relative and/or absolute shifts of the resonance frequencies or changes of the characteristics of the transmission spectrum are observed. A change in the transfer characteristics of the resonant ring, such as a shift of the resonance frequency, is related to a sample's refractive index (refractive indices) and/or change thereof. A reflecting surface may be introduced in a ring resonator. The reflecting surface can be raster-scanned for the purpose of height-profiling surface features.

Abstract: The field of the invention is that of solid-state laser gyros. One of the major problems inherent in this technology is that the optical cavity of this type of laser gyro is by nature highly unstable. To reduce this instability, controlled optical are introduced into the cavity that depend on the direction of propagation by using acoustooptic devices. Several devices are described, employing different configurations of acoustooptic devices. These devices apply in particular to laser gyros having monolithic cavities, and in particular to neodymium-doped YAG laser gyros.

Abstract: A measuring apparatus including a light source that emits light with a wavelength that allows the light to be transmitted through and reflected at each measurement target, a splitter that splits the light from the light source into measurement light and reference light, a reference mirror at which the reference light from the splitter is reflected, a mechanism for driving the reference mirror to adjust the optical path length of the reference light reflected from the reference mirror and a mechanism for measuring the interference of the reference light reflected from the reference mirror as the reference light from the splitter is radiated toward the reference mirror and measurement beams reflected from a plurality of measurement targets as the measurement light from the splitter is radiated toward the measurement targets so as to be transmitted through the measurement targets.

Abstract: The device for measuring translation, rotation or velocity includes at least a light source, a light detector, a first grating and a second grating, the first grating being mobile relative to the second grating. A incident beam reaches the first grating where it is diffracted in two beams whose directions are interchanged by the second grating, the resulting beams being then again diffracted by the first grating in an output diffraction direction where they interfere together. Both gratings are used in reflexion.