Christopher M Evans

6714308, Mar 30, 2004

Sep 3, 2002

10/233772

Christopher James Evans - Higganum CT
Michael Küchel - Oberkochen, DE

Zygo Corporation - Middlefield CT

G01B 902

356513, 356512

Interferometric apparatus and methods by which aspheric surfaces and wavefronts may be precisely measured. The apparatus is provided with two modes of operation. In one mode, the apparatus is configured generally as a Fizeau interferometer in which an aspheric reference surface is used to permit the rapid, robust measurement of the difference between the aspheric reference surface and an aspheric test optic or wavefront. In another mode of operation, the aspheric test surface itself is completely characterized through in-situ use of an interferometric scanning technique using a spherical reference surface.

6734979, May 11, 2004

Nov 5, 2002

10/288218

Christopher James Evans - Higganum CT
Michael Küchel - Oberkochen, DE

Zygo Corporation - Middlefield CT

G01B 902

356512, 356515

A method with a traceable calibration for reducing the uncertainty in the precision measurement of aspheric surfaces and wavefronts. A transmission sphere is mounted in an interferometer and its emergent wavefront is calibrated by comparing it to an optical sphere that is moved and sampled in a predetermined manner to make it act like a substantially âperfectâ sphere mounted on a slideway. Afterwards, the calibrated wavefront from the transmission sphere is used to measure a spherical artifact mounted on the slideway to calibrate its surface. A transmission asphere is then mounted in the interferometer, and its emergent wavefront is calibrated by comparing it to the calibrated spherical artifact mounted on the slideway. The calibrated aspheric wavefront from the interferometer is then used to measure an aspherical artifact mounted on the slideway to determine is surface shape. The calibration of the wavefront emerging from the transmission asphere is periodically updated to provide historical data that is used as the basis for quality improvement and assurance.

6801323, Oct 5, 2004

Oct 16, 2002

10/272168

Christopher James Evans - Higganum CT

Zygo Corporation - Middlefield CT

G01B 902

356513, 356519

Apparatus and methodology by which the radius of curvature of individual optics may be determined through the interferometric measurement of the optical length of a spherical cavity established from null tests of combinations of the individual optics and an algorithm that mutually intercompares the measured cavity lengths and radii of curvature of the individual optics.

6816267, Nov 9, 2004

Oct 22, 2002

10/277553

Christopher James Evans - Higganum CT
Michael Küchel - Oberkochen, DE
Carl A. Zanoni - Middlefield CT

Zygo Corporation - Middlefield CT

G01B 902

356515, 356512

An optical sphere of nominal radius is positioned and supported within an assembly so that is can be activated with a predetermined motion with respect to an incoming converging spherical wavefront from an interferometer to calibrate the interferometer by determining the differences between the converging spherical wavefront and the reflected wavefront from portions of the area of the optical sphere as sampled thereover. The nominal optical sphere supported and sampled in this way mimics a âperfectâ comparison sphere from which the systematic error of the interferometer wavefront may be determined. The optical sphere is preferably hollow and composed of ZerodurÂ. Internal magnets in conjunction with external induction coils provide motion control while the optical sphere is mounted on an air bearing for freedom of rotation and safety in transportation.

6876452, Apr 5, 2005

Nov 26, 2002

10/304661

Christopher James Evans - Higganum CT, US
Carl A. Zanoni - Middlefield CT, US

Zygo Corporation - Middlefield CT

G01B009/02

356498

Apparatus and methodology by which the position, angular orientation, and departure of a moving body, such as a scanning head, can be measured with high accuracy with respect to a nominally straight line as the body translates along that line. Monolithic metrology and scanning heads with integrally formed metrology surfaces are provided and fabricated of preferably identical materials having low thermal coefficients and high temporal stability. Measuring systems operate in conjunction with the integral metrology surfaces to provide interferometric information by which the position and angular attitude of the moving body is constantly monitored. Calibration arrangements are provided for determining the absolute position and attitude of the moving body with respect to the metrology frame as the two move relative to one another so that any errors can be compensated with appropriate correction functions.

7221461, May 22, 2007

Aug 11, 2005

11/201859

Christopher James Evans - Higganum CT, US

Zygo Corporation - Middlefield CT

G01B 11/02

356511

Methods and apparatus that combine the techniques of reversal (or self-calibration) to provide a low spatial frequency measurement of a part shape, independent of systematic errors in the staging used to move the part and small aperture interferometry to provide high spatial frequency information on a large part. The low spatial frequency is used to establish the rigid body motions (e. g. , tip, tilt, and piston for a plano object) to be applied to the individual sub-apertures of interferometric data in stitching them together to give a full map at high resolution of the whole part. No overlap between sub-apertures is required.

7446883, Nov 4, 2008

Jun 15, 2006

11/453677

Christopher James Evans - Higganum CT, US
William P. Kuhn - Tuscon AZ, US

Zygo Corporation - Middlefield CT

G01B 11/02

356514, 356510, 356520

A Fizeau or other interferometer is used to provide high resolution, in-situ calibration of an external angle measurement system such as widely spaced high stability plane mirror interferometers (HSPMIs)). The calibrated measurement system then measures mechanical tilt during shearing. The tilt data is used to correct the sheared data, preferably before computation of the rotationally invariant (RI) terms. Alternatively, the data may be used to compute the spurious quadratic term and correct after integration.

20060268282, Nov 30, 2006

May 23, 2006

11/438885

Christopher Evans - Higganum CT, US
Christoph Kuechel - Jena, DE
Robert Parks - Tucson AZ, US
William Kuhn - Tucson AZ, US

G01B 11/02

356515000

A Fizeau interferometer is provided with an adaptive null optic whose shape may be selectively varied in a controllable way by the selective application of external mechanical loads to enable the interferometer to be dynamically adapted to testing a variety of aspherical segments of differing shapes without the need for providing individual reference surfaces to match the various shapes of each test segment.