Matches 51 - 100 out of 200 < 1 2 3 4 >
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6341015 Compensation for measurement uncertainty due to atmospheric effects  
An apparatus and method for compensating for measurement uncertainty due to atmospheric effects. In one embodiment the apparatus includes two sources separated by a predetermined distance and two...
6330065 Gas insensitive interferometric apparatus and methods  
Displacement measuring interferometers (DMI) are disclosed for use in conjunction with apparatus for measuring and monitoring the intrinsic optical properties of the gas in the measurement leg of a...
6327039 Interferometer and method for measuring the refractive index and optical path length effects of air  
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...
6277653 Optical assaying method and system having movable sensor with multiple sensing regions  
An optical assaying method and system having a movable sensor is described. In one aspect, the present invention is a sensing system having a rotating sensor disk coated with indicator dyes...
6239877 Polarized interferential measurement wherein the modulation signal is adjusted to be equal to the duration of the measurement window  
The invention is an interferential refractometry method and device using fine measurement of the displacement of the fringes of an interference pattern between two light beams with one of the beams...
6229619 Compensation for measurement uncertainty due to atmospheric effects  
An apparatus and method for compensating for measurement uncertainty due to atmospheric effects. In one embodiment the apparatus includes two sources separated by a predetermined distance and two...
6184992 Apparatus and method for measuring flying height and a real index of refraction  
An apparatus that can measure a space between a first surface and a second surface. The apparatus may include a light source that can reflect a light beam from the first and second surfaces. A...
6172752 Method and apparatus for simultaneously interferometrically measuring optical characteristics in a noncontact manner  
Light from a light source is converged by a converging lens and is irradiated to an object to be measured through a converging lens, the object to be measured or the converging lens and the...
6169603 Compact reticle inspection system capable of inspecting a reticle with high accuracy and method of inspecting the same  
Even though a laser interferometer is affected by the changes in the environment, a reticle can be inspected with a high accuracy by synthesizing a reference image corrected appropriately to...
6157458 Achromatic quarter wave plate for an air turbulence compensating inteferometer  
An improved interferometric system with reduced air turbulence error. The system includes an optical retarder that functions as a quarter wave plate for two harmonically related frequencies. The...
6137576 Optical transducers based on liquid crystalline phases  
Optical transducers for measuring a contaminant in a gas are disclosed, whereby said contaminant interacts with a liquid crystalline phase as a sensing element in a flow cell. According to the...
6130748 Chemical sensor based on porous silicon  
In an analytic process using porous silicon, a substance is detected or its concentration in a fluid is determined based on the change in the optical property of porous silicon as a function of the...
6130439 Instrument for measuring the refractive index of a fluid  
The invention concerns in particular, an instrument for measuring the refractive index of a fluid, particularly seawater. Its object is more specifically an instrument for measuring the refractive...
6128080 Extended range interferometric refractometer  
A method and apparatus is disclosed for measuring the refractive index difference between a reference and sample liquid based on an interferometric design. The resultant device has an almost...
6124931 Apparatus and methods for measuring intrinsic optical properties of a gas  
Interferometric apparatus and method for measuring and monitoring intrinsic optical properties of a gas, especially the reciprocal dispersive power of the gas, so that information about the gas...
6057928 Free-space time-domain method for measuring thin film dielectric properties  
A non-contact method for determining the index of refraction or dielectric constant of a thin film on a substrate at a desired frequency in the GHz to THz range having a corresponding wavelength...
6034773 Length measuring machine and method using laser beams  
There is provided a length measuring machine which is not influenced by fluctuations of air or changes in temperature. At a structure, graduations are formed in a longitudinal direction, and...
6014216 Architecture for air-turbulence-compensated dual-wavelength heterodyne interferometer  
An apparatus for measuring the change in position of a stage mirror with reference to a reference mirror when the stage mirror moves between first and second positions. The apparatus includes a...
5999240 Optical retarder stack pair for transforming input light into polarization states having saturated color spectra  
A retarder stack for transforming at least partially polarized light includes a first retarder and a second retarder. The first retarder has a first retardance and a first orientation and the...
5991033 Interferometer with air turbulence compensation  
An improved interferometer measuring system that corrects for errors in the determination of the position of a measurement reflector along a measurement path due to the presence of an atmosphere...
5949542 Method of tuning an optical device  
Disclosed is a tuning method for optical interference devices which comprise at least one plurality of waveguides arranged to produce a preselected phase shift in light transmitted therethrough....
5946096 Heterodyne interferometry method for measuring physical parameters of medium  
A new method for measuring refractive index, small angle, pressure or temperature is disclosed. The method of the present invention utilizes a heterodyne interferometry technique to measure the...
5943134 Method of measuring thickness and refractive indices of component layers of laminated structure and measuring apparatus for carrying out the same  
A light beam emitted by a light source is projected through a collimator lens, a beam splitter and an objective on a sample having a laminated structure. The light beam reflected from the sample...
5920392 Environmental parameter measurement device and method for laser interferometry  
An environmental metrology device (10) containing sensor (12) elements which include a pressure sensor (20), a temperature sensor (22), and a humidity sensor (24) all located in close proximity...
5856872 Vernier index position sensor  
An index structure and method are disclosed which employ, in addition to a main diffractive grating track of an encoder, a short diffractive grating track (the vernier or index track) having a...
5838485 Superheterodyne interferometer and method for compensating the refractive index of air using electronic frequency multiplication  
A method and apparatus for measuring fluctuations in the refractive index of a gas, such as air, in a measurement path (66) may be used to measure displacement of an object (67) independent of...
5837405 Reticle  
In a reticle, a semi-transparent film pattern in place of a light blocking film pattern is used as a mask pattern having a size within a certain range, whereby an exposure system can be improved in...
5798834 Interferometric fiber optic method and apparatus for obtaining absolute static measurement using an optical frequency-time profile  
A method and apparatus for obtaining absolute static measurement values of a physical influence includes a processor which controls the operation of a laser that generates an interferometer input...
5774217 Measurement of nonlinear refractive index coefficient of optical fiber by Sagnac interferometer  
A measurement of nonlinear refractive index coefficient of an optical fiber with a Sagnac interferometer, comprises the steps of employing the optical fiber in a Sagnac interferometer, splitting a...
5767971 Apparatus for measuring refractive index of medium using light, displacement measuring system using the same apparatus, and direction-of-polarization rotating unit  
A second harmonic generation (SHG) device is used for conversion of wavelength. The direction of polarization of light beams is suitably rotated by a direction-of-polarization rotating unit, for...
5764362 Superheterodyne method and apparatus for measuring the refractive index of air using multiple-pass interferometry  
A method and apparatus for measuring fluctuations in the refractive index of a gas, such as air, in a measurement path (66) may be used to measure displacement of an object (67) independent of...
5748313 Signal-to-noise ratio of second harmonic interferometers  
The signal-to-noise ratio of the correction signal used for second harmonic interferometry is improved in two ways. First, an optical amplifier, tuned to the second harmonic frequency, is...
5715057 Reference interferometer with variable wavelength and folded measurement beam path  
The invention is directed to a reference interferometer with variable wavelength, with an interferometer splitter, a reference beam path, and a folded measurement beam path passing between two...
5710632 Methodology for the determination of the minimum and gap flying height of a thin-film slider  
A method and apparatus for measuring the flying height of a recording head that is separated from a rotating disk by an air bearing. The recording head has a trailing edge that extends from an...
5659393 Method of and device for measuring the refractive index of wafers of vitreous material  
A light beam is sent onto a wafer, at different angles of incidence, thus giving rise to fluctuations in the transmittance of the wafer, as the angle of incidence varies, because of interference...
5659392 Associated dual interferometric measurement apparatus for determining a physical property of an object  
The present invention relates to an apparatus and method for measuring physical properties of an object, such as thickness, group index of refraction, and distance to a surface. The apparatus...
5642195 Dispersion interferometer using orthogonally polarized waves  
The invention relates to dispersion interferometers for measuring a dispersion portion of the refractive index of an investigated medium by an interferometric method and can be used in the optical...
5600440 Liquid crystal interferometer  
An interferometer employs liquid crystals to effect optical path length cges in a Michelson-type interferometer. A beam splitter divides a first optical signal into second and third optical...
5585922 Dual interferometer apparatus compensating for environmental turbulence or fluctuation and for quantization error  
In this invention, in order to realize an interferometer apparatus which can correct a measurement error caused by a change in refractive index due to a fluctuation of a gas such as air with high...
5563707 Interference enhanced optical sensor for detecting chemical species  
An optical sensor for detecting gaseous or liquid chemical species including a sensing element having a flat light reflecting substrate and one or more transparent thin films which are organic or...
5557408 Method of and system for measurement of direction of surface and refractive index variations using interference fringes  
A main measuring light having a first wavelength is projected onto a work and a reference surface to produce first interference fringes and a determination light having a second wavelength slightly...
5541730 Interferometric measuring apparatus for making absolute measurements of distance or refractive index  
An absolute interferometer has part of the beam paths making up its measuring and reference arms formed in a waveguide, and part formed in air. The part formed in the waveguide are common mode so...
5537209 An interferometric measuring system having temperature compensation and improved optical configurations  
An improved interferometric measuring system wherein the system projects a first beam of light at a first measurement wavelength along a reference path to a reference reflector and a second beam of...
5526118 Apparatus for obtaining refractive index distribution information of light scattering media  
A superheterodyne split-beam system is used to measure the refractive index distribution associated with a light scattering medium. Initially, a coherent light beam is split into a first reference...
5517308 Interferometric measuring apparatus employing fixed non-zero path length difference  
A combined interferometer and refractometer includes two interferometers each of which uses a light beam produced from a common source which are split into measuring component beams and reference...
5504578 Temporal fringe pattern analysis system of a laser gain media  
An interferometric based diagnostic for experimentally determining the time-dependent OPD change in an optically heated media works by heating a glass window with a CO 2 laser, effectively...
5483344 Process and apparatus for performing differential refractive index measurements using interference of modulated light beams passing through reference and test samples  
The invention relates to the measurement of the difference between refractive indexes of two media, traversed by a light beam the beams produce an interference figure consisting of fringes having a...
5483343 Wavelength compensator in a helium ambience  
A wavelength compensator includes a reference vacuum tube having closed ends, wherein a laser beam enters the reference vacuum tube from one of the ends thereof and is reflected by the other end...
5483334 System for generating the same instantaneous pressure between two tanks  
The present invention relates to a system for generating the same instantaneous pressure between two tanks filled each with a given medium, the first tank including at least one inlet channel and...
5469261 Measurement of lens characteristics  
Method and apparatus for measuring the following lens characteristics: (a) curvature of the front and back surfaces of the lens; (b) physical thickness; and (c) index of refraction of the lens to...
Matches 51 - 100 out of 200 < 1 2 3 4 >