272 results about "Absolute measurement" patented technology

A device is proposed for high-resolution measurement, in particular for high-resolution absolute measurement of magnetic fields, having a network (1) of transitions (3) between superconductors (5, 6) which exhibit Josephson effects, called junctions below, the network comprising closed meshes (7, 8, 9, 10, 11, 12, 13), denoted by cells below, which in each case have junctions (3), which junctions are connected in a superconducting fashion, and at least three of these cells being connected in a superconducting and/or nonsuperconducting fashion. The object of the invention consists in further developing this device in such a way that it is possible to make absolute measurements of magnetic fields in a highly sensitive fashion. This object is achieved by virtue of the fact that the junctions (3) of the at least three cells (7, 8, 9) can be energized in such a way that a time-variant voltage drops in each case across at least two junctions of a cell, the time average of which voltage does not vanish, and in that the at least three cells are configured differently geometrically in such a way that the magnetic fluxes enclosed by the cells in the case of an existing magnetic field differ from one another in such a way that the frequency spectrum of the voltage response function has no significant Phi0-periodic component with reference to the magnetic flux.

Broadband energy incident on a transducer having partially or fully reflective surfaces separated by a gap which is greater than the coherence length of the broadband energy but smaller than one-half a coherence length of a band of energy within said broadband energy causes a portion of the spectral content of the broadband energy corresponding to a coherence length greater than twice the gap length to exhibit interference effects while the average power of the broadband energy remains unaffected. Splitting energy reflected from the transducer into two beams which are filtered at preferably similar center frequencies but with different pass bands yields beams which are radically different in sensitivity to changes in gap length. Analyzing the beams to derive a ratio of powers (since source intensity and fiber attenuation in a common fiber are thus self-cancelling) allows high accuracy and high resolution absolute measurement of temperature, pressure or strain. Effects of any of these physical parameters which are not of interest in a measurement can be fully compensated or made arbitrarily insignificant in a simple transducer structure of extremely small size. Use of broadband energy permits measurement over greater lengths of optical fiber.

An apparatus and a method of measuring an optical path difference in a sensing interferometer. Light from a source is directed in the sensing interferometer. The light reflected from the sensing interferometer is splitted into first and second beams respectively directed into two reference interferometers having optical path differences greater than the coherence length of the source and such that the optical signals are in quadrature. The intensities of the light transmitted by the reference interferometers and recombined light reflected from the reference interferometers are detected for measuring the optical path difference in the sensing interferometer. Additional light sources allow for correction of internal perturbations and absolute measurement of the optical path difference in the sensing interferometer.

An absolute position-sensing device is usable to measure the relative position of two elements. An absolute scale includes an integrated track extending along a measuring axis of the scale. The integrated track includes a plurality of periodic portions interleaved with a plurality of non-periodic portions. Each periodic portion includes a plurality of periodically-placed scale elements. Each non-periodic portion includes a plurality of code elements indicative of an absolute measurement value. The code elements may have a length that is narrower along the measuring axis than the length of the periodic scale elements. The offset of the periodic-placed elements relative to a readhead of the device is combined with the absolute measurement value to determine an absolute position.

The invention relates to an attitude testing apparatus and method based on an autocollimator. The apparatus mainly comprises the autocollimator, an optical hexahedron, a double-shaft electronic level meter and a pedestal with a leveling function. The method comprises the following steps: putting the attitude testing apparatus on a firm base, allowing the autocollimator to collimate a reflecting surface of an object, then collimating the optical hexahedron with an autocollimation gyro theodolite and measuring the included angle between the apparatus and a true north azimuth reference; starting the autocollimator for recording and retrieving of continuous data of the attitude of the reflecting surface of the object and starting the double-shaft electronic level meter for recording and retrieving of continuous data of horizontal attitude; and after completion of recording and retrieving of the data, processing the data of the autocollimator and the double-shaft electronic level meter by using a data processing method for the attitude testing apparatus so as to eventually obtain continuous changes of the attitude of the reflecting surface of the object in a geographic coordinate system, thereby meeting demands of continuous absolute measurement.

A modulated fibre Bragg grating strain gauge assembly for absolute gauging of strain including at least one sensor element (1) in the form of a length of optical fibre containing, along part its length, means for partially reflecting light (1a), means for generating and passing a beam of light (2a) with a spectral feature less than 0.1 nanometers in width into the at least one sensor element (1) where reflection takes place, which reflection is a substantially sinusoidal intensity variation in wavelength over a range of from 2 to 3 nanometers comprising at least two substantially sinusoidal periods such that as the at least one sensor element sustains a change in length resulting from a strain thereon, the reflected intensity varies substantially sinusoidally along the at least two sinusoidal periods, means for receiving and processing the reflected light (2b) to establish the light intensity values at one (1f) and two times (2f) a modulation frequency (1f) applied to the means for generating the beam of light (2a), and means to determine an absolute direction and magnitude of strain from a ratio of the intensity values 1f:2f.

The invention relates to a nonspherical absolute measuring system based on a multiwave front lens compensator, which comprises a phase shifting interferometer, a standard lens, a multiwave front lens compensator, an electric control adjusting device and a driver thereof, a measured nonspherical optical element, a six-dimensional adjusting frame, an electric control translation platform and a drive thereof as well as a computer control and date processing system, wherein the multiwave front lens compensator comprises a plurality of optical elements or element groups. The invention realizes error separation by a plurality of interferometry for improving the surface shape detecting precision of the nonspherical optical element and has certain flexible measuring range and larger application value.

An absolute position fiber optic encoder readhead having multiple readhead portions for sensing the displacement of respective scale grating tracks of a scale is disclosed. The detector channels of the readhead portions are fiber optic detector channels having respective phase grating masks. The fiber optic encoder readhead portions are configured to detect the displacement of a self-image of a respective scale grating track of the scale. In various exemplary embodiments, the fiber optic readhead portions are constructed according to various design relationships that provide a relatively high signal-to-noise ratio. Accordingly, high levels of displacement signal interpolation may be achieved, allowing submicrometer displacement measurements. The fiber optic encoder readhead portions may be assembled in a particularly accurate and economical manner and may be provided in a package with dimensions on the order of 1–2 millimeters, resulting in a very small overall absolute readhead dimension that is dependent on the number of readhead portions that are incorporated. Optical fiber receiver channels carrying binary optical signals derived from a scale code track may be provided in the readhead, to provide an extended absolute measurement range.

The invention provides a measuring instrument with an optical fiber Mach-Zehnder interferometer and optical fiber Michdson interferometer arrays, which comprises a broad-band light source 1, a photoelectric detector 2, a 3dB optical fiber 2 multiplied by 2 coupler 3, the optical fiber Mach-Zehnder interferometer, a transposed 3dB optical fiber 2 multiplied by 2 coupler 7, optical fiber Michdson interferometers arrays 8 and 8', and a single-mode connecting optical fiber 9, wherein, the optical fiber Mach-Zehnder interferometer consists of an attenuator 4, a self-focusing lens 5, an axicon lens 6 with total reflection angle, and the connecting optical fiber 9. The measuring instrument with the optical fiber Mach-Zehnder interferometer and the optical fiber Michdson interferometer arrays utilizes a technique that measures strain and temperature at the same time, realizes the temperature compensation technique and the array arrangement of optical fiber sensors, realizes absolute measurement under the situation that the multiple sensors are not interfered by each other, lowers the cost of single-point measurement and ensures real-time measurement; furthermore, the measuring instrument has simple techniques and easy implementation, and as standard optical fiber communication elements are adopted as the optical fiber materials and devices, the measuring instrument has low cost, easy acquisition of the optical fiber materials and devices and easy popularization.

The invention relates to an optical glass evenness testing device and a test method thereof. The testing device comprises a data acquisition system for an interferometer and a recombined system for a piece of optical glass to be tested, wherein, the interferometer and the data acquisition system consist of a laser, a beam splitter, an extender object lens, an imaging object lens, a CCD camera and an image acquisition processor; the recombined system for the optical glass to be tested comprises a flume; a bearing plate, a granite surface plate, a lifting net and the optical glass to be tested are arranged inside the flume in turn; the flume is provided with an exhaust valve and an injection valve, filled with refractive index matching liquid, communicated with a fluid reservoir which is provided with the refractive index matching liquid through a pipe and the injection valve, and is arranged on a tilt adjustment mechanism which is arranged on a shock-proof platform. The optical glass evenness testing device can directly measure the evenness of the optical glass the surface of which is not preprocessed, is absolute measurement of the refractive index evenness of the optical glass, and can reach the precision of 4x10<-7>.

The invention belongs to the micro-spectrum imaging technical field and relates to a differential confocal raman spectral test method. The method integrates the technical characteristics of the differential confocal detection method and the raman spectral detection method, forms a test method capable of realizing sample microarea spectral detection, precisely catches focus positions of excitation light beams through the differential confocal technology, detects raman spectra of corresponding positions, simultaneously adopts a designed pupil filter, sharpens Airy disc major lobes of a differential confocal raman spectral system, improves the microarea raman spectral detectability and precisely acquires microarea space spectrum information which comprises spectral information and position information of microarea samples. The method obviously improves the microarea spectral detectability of a confocal raman spectromicroscope, has absolute tracking zero points and bipolar tracking characteristics, realizes absolute measurement of physical dimension, can be widely applied in the technical fields such as biomedicine, life sciences, biophysics, biochemistry, industrial precision detection and so on to perform high-precision detection of geometric positions and spectral characteristics of microareas, and has very important application prospect.

The disclosure provides Hall effect device configurations capable of measuring magnetic fields in two dimensions (2D) and three dimensions (3D) along with associated microelectromechanical system (MEMS) manufacturing methods. The present invention includes various geometric layout configurations for 2D and 3D Hall effect devices with multidimensional magnetic field sensing elements. Advantageously, the present invention can provide, simultaneously and independently, absolute measurement of each of the components (i.e., x-, y-, and z-components) of a magnetic field. Additionally, the geometric layout configurations enable the Hall effect devices to be constructed with MEMS fabrication techniques.

An absolute position-sensing device is usable to measure the relative position of two elements. An absolute scale includes an integrated track extending along a measuring axis of the scale. The integrated track includes a plurality of code portions interleaved with, or embedded in, a plurality of periodic portions. Each periodic portion includes a plurality of periodically-placed incremental scale elements. Each code portion includes a plurality of code elements indicative of an absolute measurement value. The code elements are arranged in code element zones along the direction perpendicular to the motion axis, and are detectable by associated variations along the direction perpendicular to the motion axis. The offset of the periodically placed elements relative to a readhead of the device is combined with the absolute measurement value to determine an absolute position.

The present invention discloses a sensing device for measuring the three dimension shape and its measuring method. The said sensing device includes a projecting device, an observing device, a projecting localizer, an observing localizer and a computer for data processing. The optic axis of the projecting device and the optic axis of the observing device are crossed on the surface of the object by the relative motion and the focusing of the projecting device and the observing device, such that the viewing field of the whole field measurement and the position of the zero-order fringe are determined. The projecting device and the observing device are focused automatically by means of the object distance and the image distance of the projecting device in this viewing field, and the object distance and the image distance of the observing device in this viewing field. The camera in the observing device records the fringe patterns respectively after phase shifting and the computer calculates the three dimension surface shape of the object. The present invention achieves whole-field high accuracy and high speed absolute measurement of the three dimension object shape in the variable viewing field.

An electronic absolute position encoder is provided including a scale, a detector portion and a signal processing configuration. The scale includes a first scale pattern of signal modulating elements, wherein the first scale pattern includes a spatial characteristic of the signal modulating elements which progressively changes as a function of position along a measuring axis direction and defines an absolute measuring range. The spatial characteristic includes at least one of a spatial wavelength or a spatial frequency of the signal modulating elements and is unique at each unique position in the absolute measuring range. The detector portion includes a group of sensing elements, and the signal processing configuration determines an absolute position of the sensing elements relative to the scale within the absolute measuring range. In various implementations, the signal processing configuration may utilize Fourier transform processing and/or other processing for determining the absolute position.

A position sensor using a novel optical path array (OPA) element, an angle-selective spatial filter, and an imaging array is capable of measuring the translation and orientation relative to a target member in X, Y, Z, yaw, pitch, and roll (“6D”) simultaneously, and with high precision. A target member includes an array of target points surrounded by a contrasting surface. The position sensor uses the OPA element in combination with the angle-selective spatial filter in a target point imaging arrangement such that the imaging array of the position sensor only receives light rays that enter the OPA element according to an operable cone angle α. Accordingly, each target point generally produces a ring-shaped image having a size on the imaging array that varies with the Z position of each target point. The X-Y position of each target point image on the imaging array varies with the X-Y position of each target point. Accordingly, three or more target point images analyzed in the same image are usable to determine a 6D measurement relative to the target member. X and Y displacement of the target member can be accumulated by known methods and the other 6D measurement components are absolute measurements at any position.

A caliper atomic force microscope (AFM) comprises two AFM probes (each comprised of an oscillator and an attached tip) that operate on a sample in a coordinated manner. The coordinated operation of the AFM probes may be spatially or temporally coordinated. The result of the coordinated operation may be an image of the sample or a dimensional measurement of an unknown sample. The probes of the caliper AFM may be tilted, or the tips may be tilted at a non-orthogonal angle with respect to the probes, so as to enable the tips to access vertical sample surfaces or to enable the tips to touch each other. The tip shapes may include conical, boot-shaped, cylindrical, or spherical and materials from which the tips are fabricated may include silicon or carbon nanotubes. The oscillators may be beveled to allow the tips to operate in close proximity or in contact without interference of the oscillators. The disclosure of the present invention is discussed in terms of an atomic force (van der Waalls) interaction. Other interaction forces are contemplated, such as electrostatic force, magnetic force, and tunneling current. The caliper AFM may be calibrated with the help of a sample with known dimensions or by touching the probe tips. The tip-to-tip calibration enables absolute measurements without the need for a reference artifact, and it enables in-line calibration that may be performed during the measurement process.

The invention relates to an optical fiber white light interferometry method, in particular to a phase-shift white light interferometry method based on a 3*3 optical fiber coupler, belonging to the technical field of optical fiber sensing. A 2*2 optical fiber coupler and a 3*3 optical fiber coupler form an optical fiber M-Z interferometer, and a wavelength scanning light is injected into the optical fiber M-Z interferometer. Magnitudes of three paths of output white light interference spectrum signals are equal, and an angle of 120 degrees is formed between every two paths of output white light interference spectrum signals on the phase. When the wavelength scanning light scans from Lambda 1 to Lambda 2, three paths of output signals I1, I2 and I3 are obtained, and Delta is demodulated through computing or constructing two paths of orthorhombic signals and utilizing a derivation cross multiplying method. The Delta is subjected to the unwrapping operation to demodulate linear phase information after computed. The absolute optical path difference of the interferometer can be computed by using the linear phase information. The invention can absolutely measure the optical path difference of the optical fiber interferometer with high precision and high speed.