The State University of New York

Other

Fu-Pen Chiang

Peisen S Huang

Imin Kao

Qingying Hu

Lingtao Mao

A method of determining interior three-dimensional movement, deformation and strain in an object is provided. The method includes constructing a reference volume image, constructing a deformed volume image, wherein the deformed volume image represents the object after an applied stress and strain. The method further includes comparing the reference volume image and the deformed volume image to determine at least one displacement vector at least one of the x, y, and z directions. In addition it includes making a comparison for size of speckle features measured within the object. Based upon the at least one displacement vector, interior three-dimensional movement, deformation and strain can be measured for the object resulting from the applied stress and strain.

Method for measuring the interior three-dimensional movement, stress and strain of an object

A three dimensional surface contouring and ranging system ( ) based on a digital fringe projection ( ) and phase shifting technique is disclosed. In the system, three phase-shifted fringe patterns and an absolute phase mark pattern are used to determine the absolute phase map of the object ( ). The phase map is then converted to the absolute x, y, and z coordinates of the object surface by a transformation algorithm. A calibration procedure is used to determine accurate values of system parameters required by the transformation algorithm. The parameters are initially indirectly measured through experiments to determine their approximate values. A calibration plate is then measured by the system at various positions. An iteration algorithm is then used to estimate the system parameters.

Method and apparatus for three dimensional surface contouring and ranging using a digital video projection system

A method and apparatus for surface measurement using the shadow moire effect with the Talbot effect. The apparatus includes a specimen mount to receive a specimen having a surface to be measured, and a reference grating mounted adjacent to the specimen mount so as to be substantially parallel to a mean surface plane of the specimen. The reference grating is mounted in such a manner that the distance between the reference grating and the mean surface plane of the specimen can be adjusted to a Talbot distance &dgr;T. The apparatus also includes a light source to illuminate the specimen through the grating and a detector positioned to detect the moire fringes produced by the grating due to variation of the surface of the specimen.

Shadow moire surface measurement using Talbot effect

A novel three dimensional surface contouring method has been developed based on the fall-field fringe projection technique. A digital video projection system is used to project digitally created fringe patterns onto the object. The fringe pattern distorted by the geometry of the object surface is then captured by a high resolution CCD camera. To increase contouring resolution, purely software-based digital phase shifting technique is used, which eliminates the need for accurate positioning systems in the traditional phase shifting methods. The surface is reconstructed by applying the phase wrapping and unwrapping algorithms.

Method and apparatus for three dimensional surface contouring using a digital video projection system

Two electro-moire systems provide strain values directly. By shifting a reference grating relative to a specimen grating along the direction perpendicular to the grating line the resulting moire fringes sweep across the field. In one method two photo-detectors are used to record the cyclic intensity signals. The phase difference between the two signals is used in a special formula for the calculation of strain. In the other method only one photo-detector is used, and the frequency information of the cyclic signal is used in another formula for the calculation of strain. The electrical signals from photo-detectors are converted into digital signals and processed using a digital computer through FFT (Fast Fourier Transformer) to eliminate noise. Strain-values as small as one microstrain can be measured.

Growing community of inventors

Stony Brook, NY, United States of America

Fu-Pen Chiang