Abstract: An interferometric microscope for making interferometric measurements of locations within an object that is in a medium, there being a mismatch between indices of refraction of said object and said medium, the microscope including a source for generating an input beam; an interferometer which is configured to receive the input beam and generate therefrom a measurement beam, to focus the measurement beam onto a selected spot in the object and produce for that selected spot a return measurement beam, and to combine the return measurement beam and a reference beam to produce an interference beam; and a detector system which is positioned to receive the interference beam, wherein the return measurement beam travels along a path from the object to the detector system and wherein the interferometer includes a compensating layer of material positioned in the path of the return measurement beam, the compensating layer producing a mismatch in the index of refraction along the path of the return measurement beam that c

Abstract: A method and an apparatus for absolute refractive index measurements are disclosed, wherein a beam of spatially coherent laser light is directed perpendicularly on to a side of a capillary tube (12) and back reflected light is detected (16) over a range of angles (22) with respect to the incident light beam. The refractive index of a liquid contained in the capillary is determined from the angle at which a marked change in the intensity of the interference fringes of the interference pattern formed by said back reflected light is observed or from the amplitude of a low frequency component of the angular variation of the intensity of interference fringes.

Abstract: A scanning optical monitoring system and method are appropriate for high speed scanning of a WDM signal band. The system and method are able to identify dropped channels or, more generally, discrepancies between the determined or detected channel inventory and a perpetual inventory for the WDM signal, which perpetual inventory specifies the channels that should be present in the WDM signal assuming proper operation of the network. The system includes a tunable optical filter that scans a pass band across a signal band of a WDM signal to generate a filtered signal. A photodetector then generates an electrical signal in response to this filtered signal. A decision circuit compares the electrical signal to a threshold and a controller, which is responsive to the decision circuit, inventories the channels in the WDM signal.

Abstract: Methods and compositions are provided for detecting biomolecular interactions. The use of labels is not required and the methods can be performed in a high-throughput manner. The invention also provides optical devices useful as narrow band filters.

Abstract: The present invention relates to a sensor device and method for measuring a property associated with the introduction of or changes in a chemical, biological or physical stimulus in a localized environment, in particular to a sensor device and method for measuring the partition coefficient of a chemical stimulus such as a pharmaceutical compound.

Abstract: The present invention relates to a sensor assembly and method for measuring changes in dimension and/or composition of a sensor component (and associated factors) caused by the introduction of or changes in a chemical, physical or biological stimulus in a localized environment.

Abstract: Interferometric system for the simultaneous measurement of the index of refraction and of the thickness of transparent materials with a single measurement operation. The system employs an interferometer as a “shear interferometer” with the advantage of varying the wavelength of the luminous source. The index of refraction and the thickness are determined in two phases. Firstly it is determined the optical path analyzing the displacement of interferometric signal obtained by orthogonal incidence; successively, by means of phase recovery techniques and the previously determined optical path value, it is possible to obtain the index of refraction of the material. From the knowledge of the index and of the optical path it is obtained the material thickness.

Abstract: Methods and apparatus for reducing the effects of non-isotropic gas distributions on interferometry measurements are disclosed.

Abstract: A method of determining the diffusion rate of a given analyte into a polymer film using an optical waveguide interferometer is disclosed. A method of forming a filter media by selecting a polymer for the sorbent system of the filter media based on the diffusion rate of a given analyte into a given polymer as measured by an optical waveguide interferometer is further disclosed.

Abstract: A biosensor embodying the invention includes a sensing volume having an array of pores sized for immobilizing a first biological entity tending to bind to a second biological entity in such a manner as to change an index of refraction of the sensing volume. The biosensor further includes a ring interferometer, one volumetric section of the ring interferometer being the sensing volume, a laser for supplying light to the ring interferometer, and a photodetector for receiving light from the interferometer.

Abstract: An interferometer uses birefringent elements for splitting and combining beams of orthogonal polarization, and for changing the relative phase between the orthogonally polarized beams. A polarization sensitive detector is used to detect a fringe pattern whose periodicity is dependent on the relative optical paths traversed by the orthogonally polarized beams. In an embodiment of the invention, a birefringent beam splitter has an input path and first and second output paths. A birefringent beam combiner has first and second input paths and an output path, the first and second input paths of the birefringent beam combiner aligned respectively with the first and second output paths of the birefringent beam splitter. A polarization sensitive detector is disposed on the output path of the birefringent beam combiner to detect the periodicity of the fringe pattern.

Abstract: A device for measuring simultaneously the phase at each point of an image formed by light reflected from a sample in which the phase has been modified by plasma resonance in a thin conducting layer, the device comprising a thick transparent substrate (10) on which a thin layer of conducting material is deposited (13); a light source (1); an interferometer; an imaging means (9); and a processing means.

Abstract: The present invention provides a method and apparatus for obtaining a measure of the chromatic dispersion of a fibre bragg grating, the method comprising: disposing the grating in a reflection arm of an interferometer; inputting probe laser light into the interferometer; stepping the wavelength of the light across the reflection bandwidth of the grating, while at each step modulating the wavelength by a wavelength modulation less than the size of the respective step, and thereby producing a resulting phase modulation; and demodulating the phase modulation and determining therefrom a measure of the chromatic dispersion.

Abstract: The present invention relates to an optical sensor of air borne acoustic waves. The sensor comprises means for producing mutually coherent optical sampling and reference beams, which may be combined to form an intermediate frequency carrier, the sampling beam being exposed to the acoustic field, in which acoustic wave induced density variations occur. These density variations produce a variation in the index of refraction and thereupon a phase modulation of the sampling beam. This phase modulation may be recovered by an optical detector and a phase detector as an electrical signal representative of the acoustic signal. The invention has application to security systems.

Abstract: An interferometer and ellipsometer are combined in a metrology tool to measure the step height of a sample, which may include transparent layers. The metrology tool includes a shared light source that provides a light beam for an interferometer and a light beam for an ellipsometer, interferometer optics which direct the light beam for an interferometer to reflect off of a sample and ellipsometer optics which direct the light beam for an ellipsometer to reflect off a sample, and a detector element for receiving both the reflected light beam for an interferometer and the light beam for an ellipsometer. The light source may produce a single beam that is split into an interferometer and an ellipsometer beam with a beam splitter. In another embodiment, the interferometer and ellipsometer may share at least one of a polarizer, analyzer, or detector element.

Abstract: Methods and system for compensating for effects of changes and variations of gas refractivity in a measurement and/or reference beam path of an interferometer are disclosed.

Abstract: The glucose concentration in the bloodstream is directly correlated to the concentration of glucose in the aqueous humor. Furthermore, variation in the glucose concentration in the aqueous humor will cause like variations in its index of refraction. Thus, by measuring the refractive index of the aqueous humor, the glucose concentration in the blood can be determined. The refractive index of the aqueous humor can be measured by interferometry. In various embodiments of the invention that employ interferometry, two beams may be directed onto the eye and caused to interfere, thereby producing a fringe pattern. The fringe pattern may be analyzed to determine the index of refraction of the aqueous humor in the eye and the glucose concentration therein. The glucose level in the blood can be ascertained from this information.

Abstract: The glucose concentration in the bloodstream is directly correlated to the concentration of glucose in the aqueous humor. Furthermore, variation in the glucose concentration in the aqueous humor will cause like variations in its index of refraction. Thus, by measuring the refractive index of the aqueous humor, the glucose concentration in the blood can be determined.

Abstract: An on-chip interferometric backscatter detector (OCIBD) makes use of plastic substrates in which a rectangular sample channel is formed. While any plastic material can be used to form the channel substrate, the substrate is most preferably formed from polydimethylsiloxane (PDMS). An incident laser beam reflects off of the sample channel walls and through the sample in the channel, thereby generating backscattered reflections that create interference fringe patterns. The fringe patterns are detected by a photodetector and used to determine various properties of the sample. To provide the best results, the laser beam diameter should be no smaller than the channel width so that the entire channel will be illuminated by the beam, and preferably should be slightly, e.g., 5%, larger. This will insure that the laser light reflected off of the walls of the channel will generate the desired interference fringe patterns, despite the less than optimum rectangular geometry of the channel walls.

Abstract: The invention comprises methods and apparatus for reducing sub-harmonic cyclic errors by rotating by a small angle an interferometer or elements thereof. The rotation of the interferometer or selective elements thereof introduces a corresponding small angle between a sub-harmonic type spurious beam that subsequently interferes with either the reference or measurement beam so that the fringe contrast of the interference terms between the subharmonic spurious beam and either the reference or measurement beam is reduced by a required factor for a given use application thereby reducing nonlinearities in the phase signal.

Abstract: A method or apparatus for measuring lateral variations of a property such as thickness or refractive index of a transparent film on a semiconductor, in a region of repeated patterning comprises: illuminating over the patterned area with a beam of light of multiple wavelengths, the beam having dimensions to include repeated patterning; detecting the intensity of light reflected over the patterned area for each wavelength; producing a signal defining the variation of the intensity of the detected light as a function of the wavelength of the detected light; decomposing the signal into principal frequencies thereof, determining from the principal frequencies, values of the thickness etc. of the transparent film; and applying the values to repetitions within the repeated patterning.

Abstract: An apparatus for detecting wavelength change of a first light signal comprises an amplitude splitting interferometer and a detector. The amplitude splitting interferometer comprises first and second optical paths. The first optical path has a first index of refraction that varies with wavelength over a first wavelength band. The second optical path has a second index of refraction that is relatively constant over the first wavelength band. In operation the first light signal enters and exits the amplitude splitting interferometer forming interference light. The interference light couples to the detector which detects the wavelength change of the first light signal from the interference light. An interferometer comprises a first beam splitter, third and fourth optical paths, and a second beam splitter. The third optical path is optically coupled to the first beam splitter and has a third index of refraction that varies with wavelength over a second wavelength band.

Abstract: A sensor platform for use in sample analysis comprises a substrate (30) of refractive index (n1) and a thin, optically transparent layer (32) of refractive index (n2) on the substrate, (n2) is greater than (n1). The platform incorporates one or multiple corrugated structures in the form of periodic grooves (31), (33), which defines one or more sensing areas each for one or more capture elements. The grooves are so profiled, dimensioned and oriented that when coherent light is incident on the platform it is diffracted into individual beams or diffraction order resulting in reduction of the transmitted beam and an abnormal high reflection of the incident light thereby creates an enhanced evanescent field at the surface of the or each sensing area. The amplitude of this field at the resonant condition is greater by an order of approximately 100 than the field of prior art platforms so that the luminescence intensity created from samples on the platform is also increased by a factor of 100.

Abstract: The present invention provides a method and system for determining three-dimensional refractive gradient index distribution. The method and system of the present invention determine inhomogeneity data and calculate index of refraction changes in three-dimensions (3D). The method and system provide 3D modeling of an optical object or system that determines the three-dimensional distribution of the refractive index in the object. In one embodiment, the optical object is a blank. In different embodiments, the optical system is more than one blank. In alternative embodiments, the optical system can be a projection optics system that can include optical components such as lenses, filters, plates, and prisms. The present invention also provides a method for selecting a plurality of preferred optical elements to assemble a composite optical system with predetermined parameters.

Abstract: The present invention relates to an optical sensor of air borne acoustic waves. The sensor comprises means for producing mutually coherent optical sampling and reference beams, which may be combined to form an intermediate frequency carrier, the sampling beam being exposed to the acoustic field, in which acoustic wave induced density variations occur. These density variations produce a variation in the index of refraction and thereupon a phase modulation of the sampling beam. This phase modulation may be recovered by an optical detector and a phase detector as an electrical signal representative of the acoustic signal. The invention has application to security systems.

Abstract: The present invention provides a method for inferring optical parameters of a sample in a predictive spectral range by use of the known values of the optical parameters in a predetermined measurement spectral range. The method of the present invention capitalizes on the Forouhi-Bloomer dispersion equations for the optical constants n and k.

Abstract: An athermal interferometric wavelocker is disclosed having a beam splitter combiner and a first arm of a first material having a first refractive index, a first length, and a first coefficient of expansion; and, a second arm of a second material having a second refractive index, a second length, and a second coefficient of expansion. The refractive indices, lengths and coefficients of expansion of the first arm and the second arm are selected to provide a substantially athermal structure operating at ambient temperatures. The first arm and second arm have inner end faces that meet adjacent faces of the beam splitter and combiner. The first and second arms are of a different optical path length such that light launched into the beam splitter and combiner, interferes upon recombining, and is output from a combiner output port to provide a wavelocker signal having a detectable characteristic which varies with wavelength.

Abstract: A retroreflector has three mutually-orthogonal reflective surfaces arranged around an optical axis. The reflective surfaces stop short of the optical axis to provide a central region of the retroreflector which transmits incident light and a peripheral region of the retroreflector which retroreflects incident light. When the reflector is used in a Jamin-type interferometer with another reflector, this enables the interferometer to be used for measuring displacement between the reflectors. In the interferometer, a projected beam is disposed between a pair of return beams and/or one of the return beams is disposed between a pair of the projected beams. This enables a first contiguous area of a face of a beam splitter to be provided with a phase-shifting coating to produce a phase quadrature relationship between a pair of interferogram beams. This simplifies the masking required when applying the coating.

Abstract: A miniaturized chemical sensor features an optical microcavity coated with a surface layer, and a waveguide that evanescently couples light into the microcavity. The surface layer is adapted to chemically interact with one or more molecule species in a chemical vapor surrounding the microcavity, so as to alter the evanescent light coupling between the optical microcavity and the waveguide. The chemical interaction causes a change in the index of refraction of the microcavity, resulting in a measurable phase difference readout. The refractive index sensitivity is substantially increased, because of the high Q-value of the optical microcavity.

Abstract: Methods and system for compensating for effects of changes and variations of gas refractivity in a measurement and/or reference beam path of an interferometer are disclosed.

Abstract: Methods and apparatus for reducing the effects of non-isotropic gas distributions on interferometry measurements are disclosed.

Abstract: Methods for detection and analysis of allosteric receptor/ligand binding by changes in surface refractive index are provided. When analyzed by surface plasmon resonance, binding of such allosteric binding agents to their ligands may result in a negative deviation in the optical response (i.e., a decrease in resonance angle) or in an increase in the optical response (i.e., an increase in resonance angle) depending on the binding properties of the selected allosteric receptor. Other methods for analysis of surface refractive index are also useful in the invention. The methods of the invention are particularly useful for small ligands which would not be expected to produce detectable changes in refractive index because they do not add significant mass upon binding.

Abstract: Disclosed is a thin-film inspection device with two or more light sources. This device can control the wavelength and intensity of light and illuminate the lights with different incident angles, and are used to control the interference intensity, thereby determining optimal inspection conditions to obtain a reliable inspection result even when different kinds of thin films coexist. The thin films are formed on a flat plate and have different indices of refraction and thicknesses. An incident light control unit is disposed between the illumination unit and the flat plate for controlling the light to be incident on the patterns. A sensor unit detects a reflection light from the patterns. A reflection light control unit is disposed between the flat plate and the sensor unit and controls the light to be detected by the sensor unit. A control unit controls the movement of the illumination unit and the sensor unit.

Abstract: An optical measuring light path formed by a vacuum-side laser beam (Pa) as a reference standard and an optical measuring light path formed by a gas-side laser beam (Pb) as a dimension to be measured are coaxially located sandwiching a movable end (optical transparent body 12) of a vacuum container (11) in order to satisfy Abbe's principle requiring linear disposition of the reference standard and the dimension to be measured in measurement direction, thereby reducing measurement error in measuring air refractive index and improving measurement accuracy therefor.

Abstract: A non-contact, free-space method for determining the index of refraction of a thin film at a desired angular frequency. The method includes generating an input desired-frequency pulse and an optically detectable probe pulse. The thin film is moved in and out of the path of the input pulse, creating an output pulse that alternates between a transmitted signal, created when the film intercepts the input pulse path, and a reference signal, created when the sample is outside the input pulse path. The output pulse modulates the probe pulse, which is then detected with a photo detector, and the difference between the transmitted signal and the reference signal is calculated. The above steps are repeated over a plurality of delay times between the input pulse and the probe pulse until a complete field waveform of the differential signal is characterized. The index of refraction is calculated as a function of a ratio between the differential signal for the thin film and the reference signal.

Abstract: The glucose concentration in the bloodstream is directly correlated to the concentration of glucose in the aqueous humor. Furthermore, variation in the glucose concentration in the aqueous humor will cause like variations in its index of refraction. Thus, by measuring the refractive index of the aqueous humor, the glucose concentration in the blood can be determined.

Abstract: A method and a recording medium for measuring three-dimensional thickness profile and refractive index of transparent dielectric thin-film with some patterns or not, which is fabricated in the semiconductor and related industrial field, using white-light scanning interferometry is provided. A method for measuring a thickness profile using white-light scanning interferometry in optical system includes the following steps. A first step is to extracting a phase graph by acquiring an interference signal and performing Fourier transform. A second step is to extracting a mathematical phase graph through modeling of a measurement object. And a third step is to measuring a profile value and a thickness value by applying an optimization technique to an error function determined by using phase values which is acquired from said first step and said second step.

Abstract: A single laser is stabilized sequentially in time with respect to different wavelengths in conjunction with a continuous, preferably linear, wavelength transition for absolute optical interferometric measurement. During the wavelength transition, the number of the traversing interferences is counted in a measuring channel. The length of a measuring section may be measured in absolute terms to give known and stable wavelengths and phase measurements of the two wavelengths. Active integrated optics and residual phase measurement by compensation in the integrated optics make it possible to detect wavelength differences of 10−7 &lgr;.

Abstract: Apparatus and methods particularly suitable for use in electro-optical metrology and other applications to measure and monitor the refractive index of a gas in a measurement path and/or the change in optical path length of the measurement path due to the gas while the refractive index of the gas may be fluctuating due to turbulence or the like and/or the physical length of the measuring path may be changing. More specifically, the invention employs electronic frequency processing to provide measurements of dispersion of the refractive index, the dispersion being substantially proportional to the density of the gas, and/or measurements of dispersion of the optical path length, the dispersion of the optical path length being related to the dispersion of the refractive index and the physical length of the measurement path.

Abstract: Apparatus and methods particularly suitable for use in electro-optical metrology and other applications to measure and monitor the refractive index of a gas in a measurement path and/or the change in optical path length of the measurement path due to the gas while the refractive index of the gas may be fluctuating due to turbulence or the like and/or the physical length of the measuring path may be changing. Apparatus and method for measuring effects of the refractive index of a gas in a measurement path wherein the phase redundancy is resolved for phase signals.

Abstract: Apparatus and methods particularly suitable for use in electro-optical metrology and other applications to measure and monitor the refractive index of a gas in a measurement path and/or the change in optical path length of the measurement path due to the gas while the refractive index of the gas may be fluctuating due to turbulence or the like and/or the physical length of the measuring path may be changing.

Abstract: A device for in situ real time monitoring of atomic and molecular fluxes by use Rayleigh scattering. The flux can be generated by an effusion cell during molecular beam epitaxy. The present device uses a coherent light source, such as a helium neon laser, a high precision mirror assembly capable of providing an effective number of reflections though the flux beam and an interferometer detector to track the changes in flux.

Abstract: A method and system for correcting an angle &thgr;l indicative of a relative angular orientation of a measurement object for the effects of dispersion caused by gas along a measurement path contacting the measurement object, wherein the angle &thgr;l is measured interferometrically at a wavelength &lgr;l, the method and system including: (i) interferometrically measuring the angular orientation at a first wavelength &lgr;q to give a first angle &thgr;q indicative of the angular orientation (ii) interferometrically measuring the angular orientation at a second wavelength &lgr;u not equal to the first wavelength &lgr;q to give a second angle &thgr;u indicative of the angular orientation; and (iii) correcting the angle &thgr;l by an additive factor &Dgr;&thgr;l=−&Ggr;(&thgr;q−&thgr;u), wherein &Ggr;=(nl−1)/(nq−nu) is the reciprocal dispersive power of the gas and nl, nq, and nu are the indices of refraction of the gas at wavelengths &lgr;l, &lgr;q, and &lgr;u, respectively.

Abstract: The object of this invention is to provide a method for improving the accuracy of measurements, distance measurements in particular, made using a laser interferometer (1, 2). The method according to this invention consists of determining the air temperature along the whole path of the laser beam (3) emitted by the laser interferometer by measuring the speed of sound (5) travelling the same path, and using the resulting value to calculate the air temperature dependent adjustment on the measured value, distance measurement values in particular.

Abstract: The present invention provides a method and system for determining three-dimensional refractive gradient index distribution. The method and system of the present invention determine inhomogeneity data and calculate index of refraction changes in three-dimensions (3D). The method and system provide 3D modeling of an optical object or system that determines the three-dimensional distribution of the refractive index in the object. In one embodiment, the optical object is a blank. In different embodiments, the optical system is more than one blank. In alternative embodiments, the optical system can be a projection optics system that can include optical components such as lenses, filters, plates, and prisms. The present invention also provides a method for selecting a plurality of preferred optical elements to assemble a composite optical system with predetermined parameters.

Abstract: Apparatus and methods particularly suitable for use in electro-optical metrology and other applications to measure and monitor the refractive index of a gas in a measurement path and/or the change in optical path length of the measurement path due to the gas while the refractive index of the gas may be fluctuating due to turbulence or the like and/or the physical length of the measuring path may be changing. More specifically, the invention employs electronic frequency processing to provide measurements of dispersion of the refractive index, the dispersion being substantially proportional to the density of the gas, and/or measurements of dispersion of the optical path length, the dispersion of the optical path length being related to the dispersion of the refractive index and the physical length of the measurement path.

Abstract: Apparatus and methods particularly suitable for use in electro-optical metrology and other applications to measure and monitor the refractive index of a gas in a measurement path and/or the change in optical path length of the measurement path due to the gas while the refractive index of the gas may be fluctuating due to turbulence or the like and/or the physical length of the measuring path may be changing. More specifically, the invention employs electronic frequency processing to provide measurements of dispersion of the refractive index, the dispersion being substantially proportional to the density of the gas, and/or measurements of dispersion of the optical path length, the dispersion of the optical path length being related to the dispersion of the refractive index and the physical length of the measurement path.

Abstract: Apparatus and methods particularly suitable for use in electro-optical metrology and other applications to measure and monitor the refractive index of a gas in a measurement path and/or the change in optical path length of the measurement path due to the gas while the refractive index of the gas may be fluctuating due to turbulence or the like and/or the physical length of the measuring path may be changing. More specifically, the invention employs electronic frequency processing to provide measurements of dispersion of the refractive index, the dispersion being substantially proportional to the density of the gas, and/or measurements of dispersion of the optical path length, the dispersion of the optical path length being related to the dispersion of the refractive index and the physical length of the measurement path.

Abstract: A non-contact, free-space method for determining the index of refraction of a thin film at a desired angular frequency. The method includes generating an input desired-frequency pulse and an optically detectable probe pulse. The thin film is moved in and out of the path of the input pulse, creating an output pulse that alternates between a transmitted signal, created when the film intercepts the input pulse path, and a reference signal, created when the sample is outside the input pulse path. The output pulse modulates the probe pulse, which is then detected with a photo detector, and the difference between the transmitted signal and the reference signal is calculated. The above steps are repeated over a plurality of delay times between the input pulse and the probe pulse until a complete field waveform of the differential signal is characterized. The index of refraction is calculated as a function of a ratio between the differential signal for the thin film and the reference signal.

Abstract: An optical sensing apparatus for use in a ring laser interferometer measuring a physical quantity of an object includes a ring laser cavity formed by several internal mirrors, of which at least two internal mirrors are partly light-transmitting. The ring laser cavity generates two laser beams of an identical wavelength, the two laser beams propagating in counter direction to each other in the ring laser cavity. External mirrors are disposed at a distance from the ring laser cavity, whereby portions of the two laser beams, which pass through the internal mirrors and travel on optical paths toward the external mirrors, are reflected back into the ring laser cavity. The apparatus further includes at least one platform for mounting the external mirrors.