Corning Incorporated

Tropel Corporation

Qed Technologies International, Inc.

Corning-tropel

Andrew W Kulawiec

Mark Joseph Tronolone

Joseph C Marron

Thomas James Dunn

Nestor O Farmiga

Paul Gerard Dewa

Christopher Alan Lee

James E Platten

John H Bruning

Paul Francis Michaloski

Paul Murphy

Jon Fleig

Dag Lindquist

Don McClimans

Donald G Mcclimans

Mark J Tronolone

Thomas J Dunn

Christopher A Lee

An instrument for measuring aspheric optical surfaces includes both an optical wavefront sensor and a single-point optical profilometer. The optical wavefront sensor measures surface height variations throughout one or more areas of an aspheric test surface. The single-point profilometer measures surface height variations along one or more traces on the aspheric test surface. At least one of the traces intersects at least one of the areas, and respective spatial frames of reference for the traces and areas are relatively adapted to each other by minimizing differences between points of nominal coincidence between the areas and traces.

Integrated wavefront sensor and profilometer

Frequency-scanning interferometry is used for measuring test objects having multiple surface regions. The regions are distinguished and can be measured based on different measuring criteria. Interference data is gathered for the imageable portion of the test object from a plurality of interference patterns taken over substantially the same imageable portion at different measuring beam frequencies. The interference data is evaluated to determine topographical measures of associated points on the test object. The topographical measures are compared against a benchmark to distinguish between points on the test object that are within a first of the surface regions from points on a boundary separating the first surface region from one or more other surface regions of the imageable portion of the test object. The interference data of points within the first surface region are further evaluated to a higher accuracy.

Feature isolation for frequency-shifting interferometry

Two common-path interferometers share a measuring cavity for measuring opposite sides of opaque test parts. Interference patterns are formed between one side of the test parts and the reference surface of a first of the two interferometers, between the other side of the test parts and the reference surface of a second of the two interferometers, and between the first and second reference surfaces. The latter measurement between the reference surfaces of the two interferometers enables the measurements of the opposite sides of the test parts to be related to each other.

Overlapping common-path interferometers for two-sided measurement

A frequency-shifting interferometer gathers intensity data from a set of interference patterns produced at different measuring beam frequencies. A periodic function is matched to the intensity data gathered from the set of interference patterns over a corresponding range of measuring beam frequencies. Localized correlations involving phase offsets between the interfering portions of the measuring beam are used to inform a determination of a rate of phase change with measuring beam frequency corresponding to the optical path length difference between the interfering beam portions.

Phase-resolved measurement for frequency-shifting interferometry

A mode-monitoring system used in connection with discrete beam frequency tunable laser provides optical feedback that can be used for adjusting the laser or for other processing associated with the use of the laser. For example, the output of a frequency tunable source for a frequency-shifting interferometer can be monitored to support the acquisition or processing of more accurate interference data. A first interferometer for taking desired measurements of optical path length differences traveled by different portions of a measuring beam can be linked to a second interferometer for taking measurements of the measuring beam itself. The additional interference data can be interpreted in accordance with the invention to provide measures of beam frequency and intensity.

Optical feedback from mode-selective tuner

A frequency tuning system for a laser includes mode-matched lasing and feedback cavities. A reflective facet of the feedback cavity is adjustable for retroreflecting different feedback frequencies to the lasing cavity without changing a fixed length of the feedback cavity. A selection among resonant frequencies of the feedback cavity provides for tuning the laser through discrete resonant frequencies of the lasing cavity.

Mode-selective frequency tuning system

A scanning interferometer employs dual interferometer modules at different wavelengths to expand a dynamic range of measurement, a compound probe for measuring multiple surfaces, and a confocal optical system for distinguishing between the surfaces measured by the compound probe. Within the compound probe, miniature optics divide a test beam into two sub-test beams that are focused normal to different test surfaces. Both sub-test beams contain the different wavelengths. A separate interferometer monitors movements of the compound probe for producing absolute measures of the test surfaces.

Two-wavelength confocal interferometer for measuring multiple surfaces

Flatness and thickness variation information concerning transmissive plane-parallel test plates is obtained from a grazing incidence interferometer modified to distinguish between superimposed interference patterns containing both types of information. The grazing angle of the interferometer is varied, and unique modulation frequencies of local fringe intensities within the superimposed interference patterns are identified. The local fringe intensities attributable to the different interference patterns are distinguished by their respective modulation frequencies.

Fringe pattern discriminator for grazing incidence interferometer

A moir&eacute; interferometer has an illumination system and an imaging system that share a common focusing optic, which preferably takes the form of a concave mirror. Within the illumination system, the common focusing optic collimates light en route to a test surface. Within the imaging system, the common focusing optic telecentrically images a grating pattern appearing on the test surface onto a fringe pattern detector.

Moir&eacute; interferometer with overlapping illumination and imaging systems

A grazing incidence interferometer includes an extended light source for limiting spatial coherence of reference and test beams. A test plate is oriented at a grazing incidence to the test beam so that a first portion of the test beam is reflected from the front surface of the test plate, a second portion of the test beam is reflected from the back surface of the test plate, and the two test beam portions are sheared with respect to each other. The spatial coherence of the test beam is related to the lateral shear between the first and second test beam portions to significantly reduce contrast of an interference fringe pattern between the front and back surfaces of the test plate. Also, the reference beam is realigned with just one of the two test beam portions to favor the formation of an interference pattern between the reference surface and one of the front and back surfaces of the test plate over the formation of an interference pattern between the reference surface and the other of the front and back surfaces of the test plate.

Grazing incidence interferometry for measuring transparent

Thickness variations of semiconductor wafers are measured by interfering two beams of infrared light that are relatively modified by reflections from opposite side surfaces of the wafers. Non-null interferometric measurements are made by illuminating the wafers with diverging beams and subtracting errors caused by varying angles of incidence. Null interferometric measurements are made of both thickness variations and flatness. Infrared light, which can transmit through the wafers, is used for measuring thickness variations; and visible light, which cannot transmit through the wafers, is used for simultaneously measuring flatness.

Interferometer for measuring thickness variations of semiconductor wafers

Compound diffractive optics are used in an interferometer for simultaneously measuring multiple surfaces, making multiple measurements of individual surfaces, conveying test beams multiple times, and aligning pairs of the diffractive optics with each other. Typically, the compound optics have multiple diffraction zones that reshape test beams for reflecting from test surfaces or for combining with reference beams. The multiple diffraction zones can also exhibit different optical qualities such as transmission and reflection for conveying the test beams to and from the test surfaces.

Interferometer with compound optics for measuring cylindrical objects at

Cylindrical surfaces of a test cylinder are measured with a grazing incidence interferometer. Separate measures of a test cylinder's cylindrical surface and a master cylinder's surface are made and compared to obtain absolute measures of the test cylinder's surface. Surface fitting techniques are used to discount the effects of positioning errors, and a separate measurement is used to resolve remaining ambiguities for extending the range of test cylinder sizes that can be measured with absolute dimensions.

Interferometric measurement of absolute dimensions of cylindrical

Test surfaces are measured at grazing incidence with an interferometer using diffractive optics for manipulating reference and test beams. A leading diffractive optic separates the reference and test beams, and a following diffractive optic recombines the beams after the test beam is reflected from the test surface. Extraneous light, including light from other orders of diffraction, is isolated and blocked from combining with test and reference wavefronts.

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Fairport, NY, United States of America

Andrew W Kulawiec