Abstract: Measurement systems that separate polarization components can use retroreflectors to preserve or transform polarization and avoid unwanted mixing of the polarization components. A suitable retroreflector can include a coated cube corner reflector with retardation plates having a slow axis set at a non-zero angle away from 45° with the directions of linearly polarized component beam. The non-zero angle can be set in situ to minimize polarization mixing in a measurement system. Alternatively, a cube corner reflector with one or more polarization manipulating elements controls the polarization of a reflected beam to preserve or transform the polarization of an incident beam.
Abstract: The method according to the invention for preventing bias errors as a result of synchronous interference in fiber-optic gyroscopes (FOGs) provides for an additional signal ?E, which is periodical at the sampling clock rate and corresponds, for example, to a synchronous interference signal input to be added in the form of additional modulation to the modulation signal for a phase modulator within an MIOC. The demodulated detector signal from the FOG is preferably then correlated with the additional modulation, that is to say which is multiplied by the additional modulation and is added to it. The added-up signal, which is dependent on the error matching, controls a VCO (12) which readjusts the operating frequency of the FOG until the correlation tends to zero. The method can be used not only for phase ramp modulation but also for FOGs which operates using a random phase modulation method.
Abstract: The present invention relates to a spectrally dispersive interferometric optical apparatus having a light source, generating a phase shift, measuring the intensity of the interference signals, selectively measuring the intensity of the interference signal and determining the phase angles and/or a relative phase shift of the intensity of the interference signals. In accordance with the invention, the generating of a phase shift between components of different polarization directions in at least one of the branches of the interferometer includes a diffraction grating. The selective determination of the intensity of the interference signal in dependence on the polarization moreover permits determination of the respective intensity for the TE components and for the TM components of the interference signal with respect to the coordinate system of the diffraction grating.
Abstract: An interferential position measuring arrangement including a light source, which emits a beam of rays and an optical element, which converts the beam of rays emitted by the light source into an incoming beam of rays. A scale grating which splits the incoming beam of rays into a first partial beam of rays and a second partial beam of rays. A first scanning grating that causes splitting of the first partial beam of rays and a second scanning grating that causes splitting of the second partial beam of rays, wherein a periodically modulated interferential fringe pattern with definite spatial interferential fringe pattern period results in a detection plane. A detection arrangement which causes splitting of light entering through the detection arrangement into at least three different spatial directions and optoelectronic detector elements arranged in the at least three spatial directions for detecting phase-shifted scanning signal.
August 6, 2003
Date of Patent:
December 26, 2006
Johannes Heidenhain GmbH
Wolfgang Holzapfel, Michael Hermann, Walter Huber, Völker Hofer, Ulrich Benner, Karsten Sändig
Abstract: A method and a device for measuring the half-wave voltage of a Mach-Zehnder type optical modulator accurately and without depending on the bias variation of an optical modulator. The method of measuring the half-wave voltage of the Mach-Zehnder type optical modulator the steps of applying a high-frequency AC signal 34 and a monitoring low-frequency AC signal 35 in a superimposed manner to a Mach-Zehnder type optical modulator 1, or applying the both respectively to separately constituted electrodes, and observing the low-speed response of an output light from the optical modulator 1, wherein the half-wave voltage at a frequency to be measured of the Mach-Zehnder type optical modulator 1 is measured by using the voltage amplitude of the high-frequency AC signal 34 when the intensity change of an out put light by the monitoring low-frequency AC signal 35 is almost zero with the voltage amplitude of the high-frequency AC signal 34 kept variable.
Abstract: 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.
Abstract: A compact computer-controlled fully-packaged apparatus providing reliable multi-dimensional characterization of spherical objects in a field environment is disclosed. The apparatus has a rugged, free-space, integrated optical system with up to three lasers that generate at a laser-specific wavelength the coherent light with substantially high pointing stability. The apparatus also has a receiver. Each laser generates a pair of beams crossing each other at a predetermined laser specific angle to form a sample volume such that beams from all lasers coincide in the same spot. The receiver has photodetectors to sense the light scattered from a spherical object. Three photodetectors measure a size and one of the three photodetectors measures a first velocity component, a fourth photodetector measures a second velocity component, and a fifth photodetector measures a third velocity component of the spherical object. The velocity components are orthogonal to each other.
Abstract: A method of processing an optical element comprises providing an interferometer optics; arranging a calibrating substrate in a beam of measuring light emitted by the interferometer optics; superimposing measuring light having traversed the first and second surfaces of the calibrating substrate with reference light, and taking a first interferometric measurement of the superimposed measuring light and reference light; arranging the aspherical surface of the optical element in the beam of measuring light emitted by the interferometer optics, while the calibrating substrate is not arranged in the beam of measuring light; superimposing measuring light having interacted with the aspherical surface and the reference light, and taking a second interferometric measurement of the superimposed measuring light and reference light; determining deviations of the aspherical surface from a target shape thereof in dependence of the first and second measurements; and machining the aspherical surface of the optical element.
Abstract: An infrared spectrometer includes an infrared source system that is stabilized to provide a substantially constant output light intensity. The infrared source system includes a source element adapted to receive electrical power and to emit light at an intensity related to the electrical power received by the source element. A light detector is mounted in position to receive light emitted from the source element and to provide an output signal related to the intensity of the light received by the detector. A feedback control loop receives the signal from the detector and provides electrical power to the source element to maintain the intensity of the light output from the source element at a selected level as detected by the detector.
January 13, 2004
Date of Patent:
October 10, 2006
Thermo Electron Scientific Instruments Corporation
John M. Coffin, Robert R. Badeau, Michael R. Daun
Abstract: A method and device for measuring the wall thickness of a pipe in a pipe-rolling mill wherein a Fabry-Pérot interfero-meter has its mirror spacing set by providing an input to a linear activity for one of the mirrors from a controller receiving an input from a photodiode at the output side of the interferometer. A second control circuit regulates the amplification of that photodiode with at least one parameter derived from the rolling system, for example, the input optical signal to the interferometer or a disturbance value representing for example the temperature of the rolled product and obtained through an optical pyrometer. The incoming optical signal may be tapped to another photodiode also with a variable amplification amplifier and both amplifiers may be controlled by a second controller.
Abstract: A method for reducing a piston between a plurality of optical-collection devices configured to operate as a single optical device, such that the optical-collection devices are configured to capture select portions of a wavefront. The method includes pistoning an adjustable-optical path of at least one of the optical-collection devices through a plurality of steps; collecting a set of focused images and a set of defocused images for each step; Fourier transforming the first and second sets of images to generate respective first and second sets of spectral information for the wavefronts; deriving a set of wavefront errors based on the first and second sets of spectral information using a phase diversity algorithm; and deriving a piston value for the piston from the wavefront errors using a multi-color interferometry algorithm.
Abstract: A system and method for analyzing the characteristics of a thin film is provided. The current invention extends the capability of IR sensors to measure thin films through configuring a plurality of detection channels with appropriately chosen filters. With the multichannel infrared sensor, the characteristic signature of interference fringes can be detected simultaneously with, or instead, of absorption-based measurements.
Abstract: An interferometry system including an interferometer that includes a source imaging system that focuses an input beam onto a spot on or in the object and an object imaging system that images the spot onto a detector element as an interference beam, wherein the source imaging system is characterized by a first aperture stop that defines a first aperture and includes a first phase shifter that introduces a first phase shift in light passing through a first region of the first aperture relative to light passing through a second region of the first aperture, and wherein the object imaging system is characterized by a second aperture stop that defines a second aperture and includes a second phase shifter that introduces a second phase shift in light passing through a first region of the second aperture relative to light passing through a second region of the second aperture.
Abstract: A method of manufacturing an optical element having an optical surface of a target shape includes performing an interferometric test using an interferometer optics, wherein the interferometer optics includes a hologram that deflects a beam of measuring light by a substantial angle or that displaces an axis of symmetry of measuring light emerging from the hologram with respect to an axis of symmetry of measuring light incident on the hologram.
May 14, 2004
Date of Patent:
June 13, 2006
Carl Zeiss SMT AG
Frank Schillke, Susanne Beder, Jochen Hetzler
Abstract: It is possible to improve the manner in which the chromatic dispersion of a sample (4) is determined. To this end, the sample (4) is irradiated in an interferometer (10), with the light of a radiation source (1). A downstream polarimeter (50) measures both the power changes and the polarization changes of the interference radiation. In the downstream evaluation unit (7) the wavelength-dependent chromatic dispersion can be determined.
Abstract: An optical component especially suited for common path heterodyne interferometry comprises a symmetric dual-periscope configuration. Each periscope is substantially identical to the other with regard to certain design aspects. The resulting design is an optical component that is highly stable with variations in temperature and angular deviations.