Abstract: The invention relates to a method for measuring the spin in an optical fibre by irradiating an optical fibre with light so as to form an interference pattern, wherein the ovality of the optical fibre, which results in a continuously changing interference pattern, is used for determining the spin in the optical fibre.

Abstract: An interferometric measuring device for measuring surface characteristics, shapes, distances, and changes in distance, for example vibrations, of measurement objects (7) has a probe section (6). An advantageous design with respect to ease of use and error-free scanning is provided by the fact that the probe section (6) is subdivided into a fixed probe section (6.1) and a rotatable probe section (6.2) mechanically and optically coupled thereto, and that a beam splitter (6.3; 6.3′) is situated in the rotatable probe section (6.2) for creating a reference beam and a measuring beam for the interferometric measurement (FIG. 1).

Abstract: A deformation measuring method using electronic speckle pattern interferometry comprises the steps of subtracting an average intensity from the intensity in a time domain at each point of a speckle pattern image so as to compute the cosine component of intensity; subjecting the cosine component to Hilbert transform in a temporal domain so as to compute the sine component of intensity; determining the arctangent of the ratio between thus computed sine and cosine components so as to determine an object phase; carrying out an unwrapping operation; and outputting three-dimensional deformation distribution data in a displayable mode.

Abstract: An optical input device for an apparatus generates input signals by moving the device and an object (15) relative to each other and measures the movement by the effects of self-mixing in a diode laser (3, 5) and Doppler shift caused by the movement. For each measuring axis (X, Y, Z), radiation from a diode laser (3, 5) is converged on a window (12) across which the object (15) moves. Part of the radiation scattered by the object, whose frequency is Doppler-shifted due to the movement, re-enters the laser cavity (20) and causes a change in cavity properties. By measuring such a change, for example, by a photo diode, information about the movement is obtained. As the input device is small and cheap, it can be used in a number of different consumer apparatus.

Abstract: An absolute accuracy in the range from ±2 nm to ±1 nm for a displacement measurement value is provided by a laser interferometer displacement measuring system. A fluctuating error component that appears corresponding to the wave cycle of laser light is detected and subtracted from the measurement value while a stage is moving, thereby providing a high accuracy.

Abstract: An anodizing system for forming a anodized coating on at least a portion of a substrate thereby creating an anodized substrate is disclosed. The anodizing system includes a bath, a coating thickness monitor, at least one probe and at least one controller. The coating thickness monitor includes at least one radiation source directed at at least a portion of the anodized substrate; at least one probe for capturing at least a portion of the radiation reflected and refracted by the anodized coating on the anodized substrate, the captured radiation being at least a portion of the radiation directed the anodized substrate from the radiation source; and at least one detector in communication with the at least one probe, the at least one detector capable of processing the captured radiation to allow a determination of at least the thickness.

Abstract: A gravity sensor is disclosed which includes a first mass adapted to free fall when selectively released from an initial position. The mass has optical elements adapted to change a length of an optical path in response to movement of the mass. The sensor output is coupled to a beam splitter. One output of the splitter is coupled substantially optically directly to an interferometer. Another output of the splitter is coupled to the interferometer through an optical delay line. A frequency of the interference pattern is directly related to gravity at the mass. A second such mass having similar optics, optically coupled in series to the first mass and adapted to change the path length in opposed sign, when selectively dropped to cause time coincident movement of the two masses, generates an interference pattern having frequency related to gravity difference.

Abstract: A method for plasma etching a shallow recess or shallow trench at a predetermined depth by illuminating a wafer with a light source and using a spectrometer to receive the light reflected from the wafer begins with a step of detecting an etch start time, either by detecting a time of plasma ignition, as extracted from reflectance data, or a time extracted from the reflectance data when a wafer reflectance signal is observed to begin to change after a residual layer is etched away prior to beginning a recess or trench etch. The next step is measuring a reflectance intensity of light reflected from the wafer. Preferably, a plasma background signal is removed from this measurement and an array detector is used wherein the wavelength is determined using the reflectance model. Next, an etch rate is determined by fitting data representing the collected reflectance signal to the wafer reflectance model as a function of time, and extracting the etch rate from the model.

Abstract: Several embodiments of a microinterferometer are disclosed. A first embodiment of a microinterferometer for measuring the absolute distance to an object surface includes a substrate. The microinterferometer also includes a phase-sensitive, reflective diffraction grating formed on the substrate. The diffraction grating is configured to reflect a first portion of an incident light and transmit a second portion of the incident light, such that the second portion of the incident light is diffracted. The microinterferometer further includes a lens formed on the substrate for focusing the second portion of the incident light to a predetermined local distance, and a photo-detector for receiving interference patterns produced from the first portion of the incident light reflected from the diffraction grating and the second portion of the incident light reflected from the object surface.

Abstract: Interferometric apparatus and methods for reducing the effects of coherent artifacts in interferometers. Fringe contrast in interferograms is preserved while coherent artifacts that would otherwise be present in the interferogram because of coherent superposition of unwanted radiation generated in the interferometer are suppressed. Use is made of illumination and interferogrammetric imaging architectures that generate individual interferograms of the selected characteristics of a test surface from the perspective of different off-axis locations of illumination in an interferometer and then combine them to preserve fringe contrast while at the same time arranging for artifacts to exist at different field locations so that their contribution in the combined interferogram is diluted.

Abstract: Various options for improving throughput in an e-beam lithography apparatus are described. A slider lens moves in synchronism with the scanning motion of the electron beam.

Abstract: A methodology and concomitant system for three-dimensional near-field microscopy achieves subwavelength resolution of an object without retrieval of the optical phase. The features of this approach are three-fold: (i) the near-field phase problem is circumvented by employing measurements of the power extinguished from probe fields; (ii) the fields on which the power measurements are performed may be monitored far from the object and thus subwavelength resolution is obtained from far zone measurements; and (iii) by developing an analytic approach to the inverse problem in the form of an explicit inversion formula, an image reconstruction algorithm is produced which is strikingly robust in the presence of noise.

Abstract: Methods and apparatus for characterizing and compensating non-cyclic errors in fiber optic pickups in interferometry systems are disclosed.

Abstract: Figure errors are corrected on optical or other precision surfaces by changing the local density of material in a zone at or near the surface. Optical surface height is correlated with the localized density of the material within the same region. A change in the height of the optical surface can then be caused by a change in the localized density of the material at or near the surface.

Abstract: A method and system for measuring the position of optical transmission members in an array includes: directing a laser light from a single laser source to two or more optical transmission members in an array; creating an optical interference pattern between the laser light emanating from the two or more optical transmission members; and characterizing the optical interference pattern to provide information about a position of the two or more optical transmission members in the array. In one embodiment, the array is a one-dimensional array. In another embodiment, the array is a two-dimensional array.

Abstract: A method and system for stabilizing and demodulating an interferometer at quadrature are described. In response to receipt of a signal indicative of optical power of the interferometer, an interferometer control system determines an optical path length correction required to stabilize the interferometer at quadrature utilizing signal amplitudes appearing at multiple harmonics of the signal. In a particularly preferred embodiment, the signal amplitudes are calculated utilizing the Goertzel algorithm, a computationally efficient discrete Fourier transform. The interferometer control system then outputs an error signal indicative of the optical path length correction. In a preferred embodiment, the error signal forms the DC component of a composite stabilization signal, whose AC component is the reference modulation signal utilized to excite a transducer to modulate the optical path length of the interferometer.

Abstract: A method to determine the systematic error of an instrument that measures features of a semiconductor wafer includes the following sequential steps. Collecting sensor data from measurement runs on front and back surfaces of a wafer while the wafer is oriented at different angles to the instrument for each run, yielding a front data set and a back data set for each angle. Then organizing the data in each set into a wafer-fixed coordinate frame. Reflecting all back surface data about a diameter of the wafer creates a reflected back data set. Subtracting the reflected back data from the front data for each wafer angle, and dividing the result by two, yields an averaged wafer shape for each load angle. Adding the reflected back data to the front data and dividing the result by two, yields an instrument signature for each load angle. The symmetric corrector is calculated by taking the average over all instrument signatures at each load angle.

Abstract: The present invention expands a method of measuring the diameter, spatial distribution and so forth of micro liquid droplets by measuring the diameter of each out-of-focus image obtained by defocusing and the number of interference fringes in the out-of-focus image into a measuring method for micro gas bubbles and allows the method to be applied to a case where the spatial distribution density of micro liquid droplets and micro gas bubbles is high. A sheet-shaped parallel laser beam (2) is applied to a liquid space in which micro gas bubbles (10) are floating, and out-of-focus images of micro gas bubbles (10) irradiated with the laser beam (2) are captured at a defocus plane (8) through an objective lens (6) from a lateral direction which is at an angle &thgr; to the direction of travel of the laser beam.

Abstract: A system and method for non-linearity compensating interferometer position data includes receiving a plurality of groups of digital position values. A first group of the digital position values are digitally processed to generate a plurality of data values. The plurality of data values are digitally processed to generate at least one quasi-static non-linearity parameter. A second group of the digital position values are compensated based on the at least one non-linearity parameter.

Abstract: A method for the determination of grain orientation in a film sample is provided comprising the steps of measuring a first transient optical response of the film and determining the contribution to the transient optical response arising from a change in the energy distribution of the electrons in the sample, determining the contribution to the transient optical response arising from a propagating strain pulse within the sample, and determining the contribution to the transient optical response arising from a change in sample temperature of the sample. The grain orientation of the sample may be determined using the contributions to the transient optical response arising from the change in the energy distribution of the electrons, the propagating strain pulse, and the change in sample temperature. Additionally, a method for determination of the thickness of a film sample is provided. The grain orientation of the sample is first determined.

Abstract: Systems and methods for near-field, interferometric microscopy are disclosed in which a mask having an array of sub-wavelength apertures is used to couple near-field probe beams to a sample. The periphery of the mask further includes one or more larger apertures to couple light to the sample that forms the basis of an interferometric signal indicative of the relative distance between the mask and the sample. The interferometric signal can be the basis of a control signal in a servo system that dynamically positions the mask relative to the sample.

Abstract: A compact, reliable and highly accurate optoelectronic component can be used, in particular, as a sensor for the contactless detection of one-dimensional or multidimensional translation movements of a measurement object relative to the optoelectronic component. The optoelectronic component has a carrier body as well as an optoelectronic transmitter for emitting a coherent light beam and an optoelectronic receiver, which are applied on the carrier body. An optical device splits the light beam emitted by the optoelectronic transmitter into a reference beam and a measurement beam. The measurement beam reflected at the measurement object is received and superposed with the reference beam to form an interference beam. The interference beam is directed onto the optoelectronic receiver. The optoelectronic component furthermore contains a spacer, which is applied on the carrier body and on which the optical device is applied.

Abstract: A position measuring device for determining the position of two parts that are movable relatively to one another in the measuring direction, which, in addition, includes the feature of enabling an absolute reference to be established during the measurement. To this end, the position measuring device includes a light source, as well as a beam-splitter element, which splits the beam of rays emitted by the light source into at least one first and one second beam component, which are preferably oriented parallel to one another after leaving the beam-splitter element. Provision is also made for a reference reflector, as well as a measuring reflector, upon which the two beam components strike. A reference marking, as well as a scanning unit are arranged at the measuring reflector and at the reference reflector to produce a reference pulse signal at the position of the stationary reference reflector.

Abstract: The present invention expands a method of measuring the diameter, spatial distribution and so forth of micro liquid droplets by measuring the diameter of each out-of-focus image obtained by defocusing and the number of interference fringes in the out-of-focus image into a measuring method for micro gas bubbles and allows the method to be applied to a case where the spatial distribution density of micro liquid droplets and micro gas bubbles is high. A sheet-shaped parallel laser beam (2) is applied to a liquid space in which micro gas bubbles (10) are floating, and out-of-focus images of micro gas bubbles (10) irradiated with the laser beam (2) are captured at a defocus plane (8) through an objective lens (6) from a lateral direction which is at an angle &thgr; to the direction of travel of the laser beam.

Abstract: The present invention disclose a method for measuring a thermal expansion coefficient of a thin film, in which the thin film is first deposited on two substrates having different thermal expansion coefficients under the same conditions. For each of the two deposited substrates, a relationship between the thin film stresses and the measuring temperatures is established by using a phase shifting interferometry technique, in which the stresses in the thin films are derived by comparing the deflections of the substrates prior to and after the deposition. Based on the two relationships the thermal expansion coefficient, and elastic modulus, E f ( 1 - v f ) , can be calculated, wherein Ef and &ngr;f are the Young's modulus and Poisson's ratio of the thin film, respectively.

Abstract: An interferometric system for measuring the radius of curvature of a measurement object that includes a tunable coherent radiation source capable of emitting a radiant energy beam having a characteristic wavelength and of scanning the characteristic wavelength over a range of wavelengths; an unequal path interferometer which during operation includes a reference object and the measurement object and which receives a portion of the radiant energy beam from the tunable radiant energy source and generates an optical interference pattern; a detecting system including a detector for receiving the optical interference pattern; and a system controller connected to the tunable radiant energy source and the detecting system.

Abstract: The present invention is directed to a scanning system that uses uniform rotary motion of an optical reflector to create reciprocal linear scanning. The system converts uniform rotation into uniform longitudinal scanning. The system thereby creates mechanical reciprocal linear scanning free of reciprocally moving mechanical parts common in conventional scanning systems. In a preferred embodiment of the invention, the scanning system is incorporated within an imaging catheter for medical scanning. The optical reflector is rotatable and includes a spiral reflecting portion. The spiral reflecting portion may be a single uniform reflecting surface or may include several reflection surfaces arranged in a spiral configuration.

Abstract: An on-line measuring system for measuring a thickness of a transferred substrate includes a first image detector, a second image detector, an elevator, and a display device. After the first image detector indicates a vertical variation of a bottom surface of the substrate, the second image detector captures an image of the bottom surface of the substrate. The elevator perpendicularly moves the second image detector with respect to the bottom surface of the glass substrate, depending on the vertical variation of the bottom surface, such that a vertical distance between the bottom surface and the second image detector remains constant. Then, a controller processes the image of the bottom surface to calculate a distance between opposite edges of the bottom surface, thereby obtaining a thickness of the substrate.

Abstract: The invention relates to a method for measuring the spin in an optical fibre by irradiating an optical fibre with light so as to form an interference pattern, wherein the ovality of the optical fibre, which results in a continuously changing interference pattern, is used for determining the spin in the optical fibre.

Abstract: A method for monitoring a device fabrication process. The method includes etching into a wafer disposed inside a chamber and detecting the intensity of a portion of a light reflected from a surface of the wafer and further scattered at a scattering inside surface of the chamber.

Abstract: A method for the determination of grain orientation in a film sample is provided comprising the steps of measuring a first transient optical response of the film and determining the contribution to the transient optical response arising from a change in the energy distribution of the electrons in the sample, determining the contribution to the transient optical response arising from a propagating strain pulse within the sample, and determining the contribution to the transient optical response arising from a change in sample temperature of the sample. The grain orientation of the sample may be determined using the contributions to the transient optical response arising from the change in the energy distribution of the electrons, the propagating strain pulse, and the change in sample temperature. Additionally, a method for determination of the thickness of a film sample is provided. The grain orientation of the sample is first determined.

Abstract: A stage apparatus on which a laser interferometer is mounted includes a reticle stage (1) movable in three, X-, Y-, and &thgr;-axes, laser heads (8a-8d) each for generating a laser beam, interferometers (9a-9d) each of which is mounted on the stage (1) and splits the laser beam into reference and measurement beams, bar mirrors (11a-11c) each of which is arranged outside the stage (1) and reflects the measurement beam, and detectors (10a-10c) each for detecting the interference beam of the reference and measurement beams.

Abstract: Interferometric apparatus for measuring changes in altitude between a surface and a datum line where the apparatus comprises a dimensionally stable metrology frame and the datum line is defined in an object mounted for nominally plane translation with respect to the metrology frame in at least two orthogonal directions while experiencing relatively smaller changes in altitude in a direction nominally normal to said at least two orthogonal directions. Elongated reflector means are mounted with respect to either the metrology frame or the object to provide the surface, and at least one interferometer system is mounted at least in part on said object for movement therewith.

Abstract: A method for the determination of grain orientation in a film sample is provided comprising the steps of measuring a first transient optical response of the film and determining the contribution to the transient optical response arising from a change in the energy distribution of the electrons in the sample, determining the contribution to the transient optical response arising from a propagating strain pulse within the sample, and determining the contribution to the transient optical response arising from a change in sample temperature of the sample. The grain orientation of the sample may be determined using the contributions to the transient optical response arising from the change in the energy distribution of the electrons, the propagating strain pulse, and the change in sample temperature. Additionally, a method for determination of the thickness of a film sample is provided. The grain orientation of the sample is first determined.

Abstract: A precision grating period measurement system uses a pair of properly positioned photodetectors to provide sub-Angstrom resolution. That is, the absolute position of a first detector with respect to a zero point in the measurement system is assured by including a second photodetector that measures a retroreflected signal. The system is then “zeroed” on the retroreflected signal such that the subsequent measurements recorded by the first photodetector are a precise measurement of the grating period.

Abstract: A method of unambiguous range estimation is provided for use with a range imaging system that derives phase images from image pixels of a digital image. The method involves generating (a) a first phase image having one or more ambiguous phase intervals and (b) at least one additional phase image that is generated by shifting the phase intervals of the first phase image. Then at least one region of intersection between phase intervals in the two phase images is identified. Finally, the phase of at least one of the ambiguous phase intervals in the first phase image is adjusted based on values of the phase of the image pixels that belong to the region of intersection. As a result, the phase adjustment unwraps the phase ambiguity in the phase intervals of the first phase image.

Abstract: A method and apparatus are provided for measuring a depth geometry of a structure on a semiconductor substrate including a plurality of recessed and non-recessed portions, wherein one of the recessed and non-recessed portions includes a reference interface and one of the recessed and non-recessed portions has a dielectric layer thereon. A broadband light source irradiates the substrate and a detector detects a first spectral component comprising light reflected from the non-recessed portions, a second spectral component comprising light reflected from the recessed portions, and a third spectral component comprising light reflected from the dielectric layer. Spectral reflectance information of the detected rays is stored and a plot of reflectance intensity versus wavelength is generated. A depth geometry of one of the recessed portions and the dielectric layer are determined relative to the reference interface, based on an interferometric analysis of the plot.

Abstract: A wafer-cleaning module is disclosed for removing contaminants from a semiconductor wafer prior to measurement in a metrology tool. The cleaning module includes a heating chamber including a heater plate for heating the wafer by conduction. A separate cooling chamber is provided to cool the wafer. The system is controlled by a processor so the heating cycle, cooling cycle and the time periods between these cycles and the measurement cycle are uniform for all wafers.

Abstract: The present invention provides a method and associated apparatus with which it is possible to implement both shape detection and also displacement measurement in particular using partially identical working steps. A method according to the invention for determining the displacement of at least a part of the surface of a measurement object between an initial condition and a measurement condition and the shape of that surface of the measurement object is characterized in that the operation of determining the shape and the operation of determining the displacement are effected with the same measurement method using the speckle effect.