US 12,299,915 B2Granted

X-ray digital image correlation

AssigneeNational Technology & Engineering Solutions of Sandia, LLC

InventorsEnrico C. Quintana, Elizabeth M. C. Jones, Daniel Peter Rohe, Bryan Lee Witt, Timothy J. Miller, Phillip L. Reu

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Abstract

A method of X-ray digital image correlation is provided. The method comprises aligning cameras of an X-ray imaging system, wherein the X-ray imaging system comprises two X-ray sources pointed at a target area at a stereo angle and two corresponding X-ray detectors behind the target area. The X-ray imaging system is tuned to determine power levels of the X-ray sources that maximize image contrast and signal-to-noise ratio. The system is calibrated to determine intrinsic and extrinsic stereoscopic imaging parameters. A specimen with a random contrast pattern comprising an X-ray attenuating material is placed in the target area. Stereoscopic X-ray images are taken of the specimen and processed according to the power levels of the X-ray sources to maximize image contrast and signal-to-noise ratio and remove background objects. Kinematic quantities are determined according to changes in the contrast pattern over a number of successive images.

Claims19

Dependent claims

A method of X-ray digital image correlation, the method comprising:

aligning cameras of an X-ray imaging system, by
performing an initial alignment with a light source co-located with an X-ray source and a translucent medium positioned between the light source and a camera of the plurality of cameras, wherein the translucent medium is used in place of a scintillator that will ultimately be used to collect X-ray images;
removing the translucent medium;
performing two-dimensional calibration on the camera to identify distortion parameters and image center;
orienting the camera such that the X-ray source is aligned at the image center;
placing the translucent medium back between the light source and the camera;
determining an exact target position;
and
replacing the translucent medium with a scintillator panel, wherein the scintillator panel is flat and positioned perpendicular to a camera optical axis, wherein the X-ray imaging system comprises two X-ray sources pointed at a target area at a stereo angle and two corresponding X-ray detectors behind the target area, wherein the cameras form part of the X-ray detectors;
tuning the X-ray imaging system to determine power levels of the X-ray sources that maximize image contrast and signal-to-noise ratio;
calibrating the X-ray imaging system to determine intrinsic and extrinsic stereoscopic imaging parameters of the X-ray imaging system;
placing a specimen in the target area after calibrating the X-ray imaging system, wherein a random contrast pattern comprising an X-ray attenuating material is deposited on the specimen;
taking, with the X-ray imaging system, a number of stereoscopic X-ray images of the specimen over a number of time steps;
preprocessing, by a computer system according to the power levels of the X-ray sources, the stereoscopic X-ray images to maximize image contrast and signal-to-noise ratio and remove background objects;
and
determining, by the computer system, from the stereoscopic X-ray images, kinematic quantities of the specimen according to changes in the random contrast pattern deposited on the specimen over a number of successive stereoscopic X-ray images.

13 more elements

A method of X-ray digital image correlation, the method comprising:

tuning an X-ray imaging system, wherein the X-ray imaging system comprises two X-ray sources pointed at a target area at a stereo angle and two corresponding X-ray detectors behind the target area, and wherein tuning determines power levels of the X-ray sources that maximize image contrast and signal-to-noise ratio;
calibrating the X-ray imaging system, wherein calibration comprises:
taking stereoscopic X-ray images of a dot-grid calibration target mounted on a motorized stage assembly as the stage assembly rotates, tilts, and translates the dot-grid calibration target throughout a defined calibration volume;
preprocessing the stereoscopic X-ray images of the dot-grid calibration target to enhance image contrast and signal-to-noise ratio;
replacing the dot-grid calibration target with a speckled calibration target on the stage assembly;
taking stereoscopic X-ray images of a speckled calibration target as the stage assembly rotates, tilts, and translates the speckled calibration target throughout the defined calibration volume;
preprocessing the stereoscopic X-ray images of the speckled calibration target to enhance image contrast and signal-to-noise ratio;
and
correlating the stereoscopic X-ray images of the speckled calibration target to determine intrinsic and extrinsic stereoscopic imaging parameters of the X-ray imaging system;
placing a specimen in the target area after calibrating the X-ray imaging system, wherein a random contrast pattern comprising an X-ray attenuating material is deposited on the specimen;
taking, with the X-ray imaging system, a number of stereoscopic X-ray images of the specimen over a number of time steps;
applying at least one of motion, loading, or deformation to the specimen concurrently with taking the stereoscopic X-ray images;
preprocessing, by a computer system according to power levels of the X-ray sources, the stereoscopic X-ray images to maximize image contrast and signal-to-noise ratio and remove background objects;
and
determining, by the computer system, from the stereoscopic X-ray images, kinematic quantities of the specimen according to changes in the random contrast pattern deposited on the specimen over a number of successive stereoscopic X-ray images.

12 more elements

An X-ray digital image correlation system, comprising:

an X-ray imaging system comprising:
two X-ray sources pointed at a target area at a stereo angle, wherein power levels of the X-ray sources are set to maximize image contrast and signal-to-noise ratio;
and two corresponding X-ray detectors behind the target area, wherein each X-ray detector comprises a camera and a scintillator;
a computer system programmed to:
tune the X-ray imaging system to determine power levels of the X-ray sources that maximize image contrast and signal-to-noise ratio;
calibrate the X-ray imaging system to determine intrinsic and extrinsic stereoscopic imaging parameters of the X-ray imaging system;
take a number of stereoscopic X-ray images of a specimen in the target area over a number of time steps, wherein a random contrast pattern comprises an X-ray attenuating material is deposited on the specimen;
preprocess the stereoscopic X-ray images according to the power levels of the X-ray sources to maximize image contrast and signal-to-noise ratio and remove background objects;
determine, from the stereoscopic X-ray images, kinematic quantities of the specimen according to changes in the random contrast pattern deposited on the specimen over a number of successive stereoscopic X-ray images and system by:
select a subset of X-ray images from all X-ray images taken by the X-ray imaging determining an average image brightness of the X-ray images;
performing course image search of the X-ray images;
upon detection of average image brightness above a specified threshold, switching from course image search to fine image search, wherein the X-ray images are stepped through one by one until a brightness of the X-ray images is no longer above the specified threshold;
averaging all X-ray images found during fine image search into a single averaged X-ray image;
and
saving the averaged X-ray image.

12 more elements

Dependencies are inferred from the claim text.