Apre Instruments, Inc.

Engineering Synthesis Design, Inc.

Trology, LLC

Other

Electro-optical Sciences, Inc.

Szwaykowski, Piotr

Olszak, Artur

Smithe, Robert

Piotr Szwaykowski

Raymond Joseph Castonguay

Artur Olszak

Frederick Nicholas Bushroe

Michael Greenebaum

Robert Smythe

Theodore S Shultz

Federick N Bushroe

Robert Smithe

The range of measurement in spectrally controlled interferometry (SCI) is extended by superimposing multiple modulations on the low-coherence light used for the measurement. Optimally, a spectrally controllable light source modulated sinusoidally with low spectral frequency is combined with a delay line, such as provided by a Michelson interferometer. The resulting light is injected into a Fizeau interferometer to generate localized fringes at a distance corresponding to the effect of the spectrally modulated source combined with the optical path difference produced by the delay line. The combination provides a convenient way to practice SCI with all its advantages and with a range that can be extended to the degree required for any practically foreseeable application. Alternatively, a single source capable of multiple modulations can be used instead of a separate second modulator component.

Extending the range of spectrally controlled interferometry by superposition of multiple spectral modulations

The range of measurement in spectrally controlled interferometry (SCI) is extended by superimposing multiple modulations on the low-coherence light used for the measurement. Optimally, a spectrally controllable light source modulated sinusoidally with low spectral frequency is combined with a delay line, such as provided by a Michelson interferometer. The resulting light is injected into a Fizeau interferometer to generate localized fringes at a distance corresponding to the effect of the spectrally modulated source combined with the optical path difference produced by the delay line. The combination provides a convenient way to practice SCI with all its advantages and with a range that can be extended to the degree required for any practically foreseeable application.

A non-contact optical probe utilizes an optical reference surface that projects a curved test wavefront toward the test surface and detects it by creating curved interferometric fringes localized in space in front of the reference surface. When a point to be measured on the test surface intersects the location of the fringes, the condition is detected by the probe. Because the fringes are localized at a known position in space with respect to a reference system, the precise coordinate of the surface point can be established. Such localized fringes are preferably produced by a spectrally controllable light source. The curvature of the fringes ensures a sufficiently large angle of acceptance for the probe to capture light reflected from points of high surface slope. The probe is particularly suitable for coordinate measurement machines.

Interferometric non-contact optical probe and measurement

Polarization based interferometric methods suffer from errors caused by the internal instrument birefringence. Disclosed herein are methods for using dual interferometric measurements allow separating the influence of instrument errors (e.g., due to geometry and birefringence errors) and the measured part. The interferometric system error in an interferometry system having two light sources orthogonally polarized with respect to each other wherein each light source reflects from a reference surface and a test surface, creating four reflected beams (Wr, Vr, Wt, Vt), may be determined by performing a first interference measurement (M) from Wr-Vt. A second interference measurement (M) from Wt-Vr is performed and a third measurement (M), indicative of the interferometric system error, is calculated by averaging the first and second measurements ([M+M]/2).

Methods for determining error in an interferometry system

A computer generated phase map and corresponding set of interference fringes calculated from a theoretical prescription of a measured aspheric surface comprises a Computer Generated Reference (CGR) that is used in an interferometer equipped with a spherical and/or flat reference element. moir&#xe9; fringes created between real interference fringes and the CGR describe the difference between the measured object and its prescription. The moir&#xe9; fringes can be nulled making the measurement of the aspheric surface analogous to the measurements of the regular spherical and/or flat surfaces.

Computer generated reference for measurements of aspheric surfaces

A simultaneous phase-shifting white light scanning interferometer comprises a white light scanning interferometer, a simultaneous phase-shifting module, and a scanner. Light from a short coherence length light source may be polarized and then split, by a polarization type beam-splitter, into orthogonally polarized reference and test beams. The simultaneous phase-shifting module comprises a plurality of detectors, allows for controlled phase shifts between the reference and test beams, and creates at least three independent interferograms, each with different phase shifts between the reference and test beams. The scanner translates the simultaneous phase-shifting module with respect to an object under measurement.

White light scanning interferometer with simultaneous phase-shifting module

A source module () generates mutually orthogonally polarized beams of light as emanating from two spatially separated point sources (Sv, Sw) for use in a phase shifting interferometer.

Interferometric system with reduced vibration sensitivity and related method

An optical measuring apparatus for comprising, in combination, a polarization type interferometer including a polarization type beam splitter in which a polarized beam of light is split into orthogonally polarized reference and test beams, an array of detectors arranged in a line for creating a plurality of phase shifting interferograms, and a scanning device for moving the object in a direction perpendicular to a long axis of the detectors.

Scanning simultaneous phase-shifting interferometer

A back-end assembly for use with a front-end assembly in acquiring phase-shifted interferograms having a plurality of imaging modules (Ma, Mb, Mc). Each module (Ma, Mb, Mc) has a quarter wave plate (), a polarizer (), and an image sensor () so that each polarizer has a different rotation orientation thus acquiring phase-shifted interferograms.

Simultaneous phase shifting module for use in interferometry

Common path, two beam interferometers and interferometric measurement systems employ a voltage controlled variable phase retarder enabling rapid stepping of the relative phase between two interfering optical beams by suitable control of the voltage. The beams need not be laterally separated. A compact beam expander with a ball lens is preferably included. The system is compact enough to be contained in a hand-held unit. The system can be used for surface mapping, testing of optical components and detecting the motion of mechanical objects, for example. It is particularly well suited for the mapping of the skin of a live subject. An optimum fringe period and optimum illumination wavelengths for imaging skin are disclosed, enabling the topography of substantial areas of human skin to be rapidly and accurately measured, in times on the order of one-tenth of a second. Methods of conducting interferometric analysis are disclosed, as well.

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Tucson, AZ, United States of America

Piotr Szwaykowski