Abstract: A method is disclosed for contactless determination of product characteristics, particularly in continuous or discontinuous fabrication of layer systems formed of a plurality of layers with different optical characteristics. The measuring apparatus and measurement methods for determining the characteristics of one of the respective layers are predetermined depending on the optical characteristics of this layer and depending on the optical characteristics of layers situated above it in the measuring direction. In a measuring device for this purpose, a plurality of detectors are provided for wavelength regions directly adjoining one another. The detectors and the signal processing device are constructed such that the light coming from the measurement surface with wavelengths of 200 nm to more than 2400 nm is evaluated in its entirety.

Abstract: An apparatus and method of sensing fluid flow are provided to measure fluid flow rates in production tubing, pipelines, open wells and tunnels. The proposed invention takes advantage of a sensor with processing means to interpret the fluid flow rate, the sensor being responsive to the mechanical perturbations of the sensor itself arising from the impingement of turbulent fluid flow on the sensor. In operation, the sensor is mounted in the fluid flow such that the fluid flows through an aperture in the sensor and/or around the outside surface of the sensor. The sensor of the invention bears definite advantage over known sensors and it is particularly suited to downhole oil and gas applications. Preferably, the invention employs fiber optic sensing techniques which are amenable to multiplexing a plurality of the sensors with long down leads. Such an arrangement is robust to withstand the high temperature and pressure environment.

Abstract: An alignment mark includes a first mark usable for global alignment measurement in the direction of a scribe line, and a second mark usable for pre-alignment measurement in a direction perpendicular to the direction of the scribe line. The first mark is formed by arranging a plurality of strip-shaped X measurement marks whose longitudinal direction is perpendicular to the direction of the scribe line. In the second mark, the strip-shaped second measurement marks are arranged at the two ends of the first mark such that the longitudinal direction of the second measurement mark is perpendicular to that of the first measurement mark. The alignment mark can be shared by global alignment and pre-alignment, and applied to a narrow scribe line.

Abstract: A system for performing single wavelength ellipsometry (SWE) on a thin film on a multi-layer substrate such as silicon-on-insulator (SOI) applies a measurement beam having an absorption distance less than the thickness of the superficial layer of the multi-layer substrate. For example, for an SOI substrate, the measurement beam is selected to have a wavelength that results in an absorption distance that is less than the superficial silicon layer thickness. The system can include a cleaning laser to provide concurrent cleaning to enhance measurement accuracy without negatively impacting throughput. The measurement beam source can be configured to provide a measurement beam at one wavelength and a cleaning beam at a longer wavelength, so that the absorption depth of the measurement beam is less than the superficial layer thickness while the absorption depth of the cleaning beam is greater than the superficial layer thickness.

Abstract: An interferometer system comprises a reference surface, a support for an object providing an object surface, a radiation source for emitting radiation of an adjustable frequency onto the reference surface and the object surface, a position-sensitive radiation detector, a controller for adjusting a plurality of different frequencies of the radiation emitted by the radiation source, and an integrator for averaging the interference patterns superposed on the radiation detector at different frequencies. Moreover, there is provided a method for recording an interferogram, a method for providing an object with a target surface as well as a method for manufacturing an object with a target surface.

Abstract: Apparatus for optical assessment of a sample includes a radiation source, adapted to generate a beam of coherent radiation, and traveling lens optics, adapted to focus the beam so as to generate first and second spots on a surface of the sample and to scan the spots together over the surface. Collection optics are positioned to collect the radiation scattered from the first and second spots and to focus the collected radiation so as to generate a pattern of interference fringes. A detector detects a change in the pattern of the interference fringes as the spots are scanned over the surface.

Abstract: Power of multi-path interference light is measured by setting the cycle of pulse modulation for a light source in correspondence with the length of an optical medium of a target to be measured, by inputting pulse light after being modulated to the target to be measured, by modulating the pulse signal light output from the target to be measured with the use of a pulse signal for modulation having the same cycle as the set cycle, and by observing the wavelength dependency of the power of the light after being modulated. In this way, a modulation condition is set according to a condition of a target to be measured when multi-path interference light caused by double Rayleigh scattering light or reflection at the end of a connector is measured with a pulse-OSA method, so that measurement accuracy is improved.

Abstract: A method is described that involves tracking a fringe line disturbance that has breached its field of reference. The method also involves translating each pixel location of the tracked fringe line disturbance to an x,y,zs data point. x and y represent a position on the plane of an interferometer's sample stage. zs represents the height of a sample above the x,y position. The sample is placed upon the sample stage of an inteferometer so as to create the fringe line disturbance. The fringe line disturbance is observed on the interferometer's detector.

Abstract: Methods for determining an appropriate tuning rate for interferometry systems employing phase-shifting interferometry are disclosed.

Abstract: According to one aspect of the disclosure and a particular example application directed to a flip-chip packaged die, a method for detecting a defect in a surface of the die includes directing light through a first beam splitter; directing light of a known wavelength at the beam splitter, wherein the first beam splitter is adapted to direct a first beam of light into the back side of the semiconductor die which reflects a second beam of light back; and redirecting the second beam to a second beam splitter, the second beam splitter generating third and fourth beams of light. Analysis of the third and fourth beams of light is then performed, and this analysis can include using detectors in respective paths of the third and fourth beams of light to generate an arrival time differential and then comparing the differential with a reference previously generated using a nondefective die.

Abstract: An ophthalmic instrument (for obtaining high resolution, wide field of area hyperspectral retinal images for various sized eyes) includes a fundus retinal imager, (which includes optics for illuminating and imaging the retina of the eye); apparatus for generating a real time image of the area being imaged and the location of the hyperspectral region of interest; a high efficiency spatially modulated common path Fourier transform hyperspectral imager, a high resolution detector optically coupled to the hyperspectral and fundus imager optics; and a computer (which is connected to the real time scene imager, the illumination source, and the high resolution camera) including an algorithm for recovery and calibration of the hyperspectral images.

Abstract: Interferometers can be configured to maintain a measurement beam substantially orthogonal to a plane measurement mirror and to minimize the lateral beam shear between the measurement and reference beam components of the output beam to a detector. These interferometers use a dynamic beam steering element to redirect the input beam in response to changes in the orientation of the measurement plane mirror. These interferometers may be further configured to measure displacement and change in orientation of the plane mirror or configured in a combination of single pass interferometers fed by the input beam for measuring displacement and change in orientation of the plane mirror.

Abstract: A swept wavelength meter provides a real-time wavelength calibration scheme for a swept laser. The calibration scheme generates an electrical signal from a swept optical output of the swept laser that is cyclical with respect to the wavelength of the swept optical output over a defined range of wavelengths. The point on the electrical signal at any given time provides an accurate phase for the swept optical output at that point. The electrical signal in turn is calibrated by generating calibration references from the swept optical output using known absorption lines within the defined range of interest. The wavelength of the swept laser is calibrated as a function of a reference wavelength from the known absorption lines and the phase at the given point. Simultaneously forward and reflective measurements may be taken, with the forward measurement being used as a normalizing measurement for determining insertion and return loss automatically for a device under test.

Abstract: The invention relates to Fabry-Perot interferometers (FFPI) comprising two or more optically coupled tunable all-fiber Fabry-Perot component filters, wherein the Fabry-Perot cavity of the filter is formed within a bare section of optical fiber held within a fiber ferrule. The wavelength transmitted by the interferometer can be tuned thermally or electromechanically for a fiber containing the Fabry-Perot cavity bonded into a groove of a metal substrate. The interferometer can be tuned by changing the length of Fabry-Perot cavity, including by the use of a piezoelectric transducer.

Abstract: A system for forming an image of an object in a turbid medium comprises a light source for producing a coherent light beam of a selected frequency that is divided by a beamsplitter into a reference beam directed along a first optical path and a signal beam directed along a second optical path where the object to be imaged is located. The signal beam impinges upon the object and reflects back toward the beamsplitter. The reference beam is modulated to shift its frequency. A mirror reflects the reference beam back toward the beamsplitter for combination with the signal beam to produce an output optical signal. A photodetector receives the output optical signal from the beamsplitter and produces an electrical signal having a frequency related to shifts in frequency between the reference beam and the signal beam and having an amplitude proportional to the image intensity.

Abstract: A wavelength monitor 10 having a Michelson interferometer (or Mach-Zehnder) optical system 11 of a spatial light type having optical input from a light source has an interference pattern generating means 12 which inclines the wavefronts of interfering beams of collimated light to generate an interference pattern in the light intensity distribution in an interference light beam planes a first slit 107 and a second slit 108 which are adjustable in position and provided in front of a first photo-detector 109 and a second photo-detector, respectively, which receive split beams of interference light, and a signal processing means 111 by which the changes in the intensity of light from the first photo-detector 109 and the second photo-detector 110 are counted and subjected to necessary arithmetic operations to output signals representing wavelength data for the input light.

Abstract: A method and an apparatus for enhancing a resolving power of a tunable optical filter. An optical input is applied to the tunable filter. An electrical signal is applied to the tunable optical filter. The electrical signal has a first component that has a first frequency and a second component that has a second frequency. The second frequency is higher than the first frequency. An optical output of the tunable optical filter is applied to a photodetector. The electrical output from the photodetector is applied to a lock-in detector. The lock-in detector receives an input from frequency doubling circuitry. An output of the lock-in detector is monitored.

Abstract: There is provided a shape measuring apparatus using an interferometer comprising a lens for condensing temporarily light waves from a light source, and a light wave shaping plate having a pinhole with suitable size adapted to convert the condensed light waves into an ideal spherical wave and a window provided in the vicinity of the pinhole and having enough size to pass therethrough light wave surface information, in which at least one lens having a reference surface and a surface to be measured the optical axes of which are slightly decentered in an optical path of the light waves passed through the pinhole is arranged in a position where the light waves which are made incident perpendicularly to the reference surface to be reflected therefrom pass through the pinhole again, and the light reflected from the surface to be measured pass through the window, and the reflected light reflected by the reference surface to pass through the pinhole again and the reflected light reflected by the surface to be measured

Abstract: Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics having spherical, mildly aspherical and multiple, mildly aspherical surfaces. At least a partial spherical wavefront is generated from a known origin along a scanning axis through the use of a spherical reference surface positioned along the scanning axis upstream of the known origin. A test optic is aligned with respect to the scanning axis and selectively moved along said scanning axis relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at one or more radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency to generate interferograms containing phase information about the differences in optical path length between the center of the test optic and the one or more radial positions.

Abstract: A Method for measuring vibrations in small and microscopic objects is disclosed. The method includes the steps of vibrating the object at a frequency, illuminating the object with a light source which is phase modulated at the same frequency, collecting data from a detector array, operating an algorithm to calculate the size of interference modulation between the light waves, operating an algorithm based on multiple calculation of the modulation at different vibration phases between the excitation of the object on one hand, and the reference phase modulation on the other, and operating an algorithm based on use of the result from the calculation of the second modulation, calculating amplitude values and phase values for the vibration of the surface of the object.