X-ray projection measurement image size calibration method

Abstract

The invention discloses an X-ray projection measurement image size calibration method. The method comprises the following steps: sequentially placing an X-ray source, a rotating mechanism and a detector along the direction of a measurement optical axis, namely, positioning the rotating mechanism between the X-ray source and the detector, keeping the relative positions of the X-ray source, the rotating mechanism and the detector unchanged along the direction of the optical axis, fixing a sample on the rotating mechanism, enabling the rotating shaft of the rotating mechanism to be perpendicular to the measuring optical axis, obtaining two X-ray projection images of the sample at the current angle and after the sample is rotated by 180 degrees, measuring the size of the same feature structure in the sample in the two X-ray projection images, and calculating the real size of the feature structure by applying the two sizes. According to the invention, the accurate sizes of all the characteristic structures parallel to the measured cross section in the sample can be obtained only through two times of projection imaging, the positions of the characteristic structures on different cross sections do not need to be adjusted respectively, and the measurement efficiency is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of X-ray projection measurement, and more specifically, the invention relates to an image size calibration method for X-ray projection measurement. Background technique [0002] The X-ray projection measurement method is widely used in industrial flaw detection, imaging medicine, mineral exploration and other fields. This technology uses X-rays as the detection medium to image the sample through the X-ray flat panel detector or negative film, and then obtain the internal structure information of the sample. . [0003] Usually, X-ray projection measurement is realized by a micro-focus X-ray source. Based on the principle of geometric magnification, the geometric magnification ratio of the image is the ratio of the distance from the X-ray source focus to the detector to the distance from the X-ray source focus to the sample. In order to obtain the size of the sample to be measured, the geometric magnification...

AI Technical Summary

Problems solved by technology

[0004] There are certain problems in the above two methods of measuring sample size by X-ray projection. It is usually difficult to obtain the geometric magnification ratio of the image by measuring the distance from the focus of the X-ray source to the detector and the distance from the focus of the X-ray source to the sample. The characteristic structure to be measured is often inside the sample, and its accurate position information cannot be obtained in advance. In addition, the focus of the X-ray source is usually located inside the X-ray tube, and its accurate position information cannot be obtained. Even if the above-mentioned Two distances, the influence of the measurement error on the error of the geometric magnification ratio cannot be ignored

There are also deficiencies in the method of calibrating the pixel size of the X-ray projection image through a standard sample of known size. On the one hand, if the standard sample and the sample to be tested are measured separately, it is difficult to ensure the consistency of the conditions between the two measurements. For example, the focus drift of the X-ray source, the change of the physical position of the two measurements, etc., will introduce measurement errors; on the other hand, if the standard sample and the sample to be tested are measured at the same time, it is difficult to ensure that the position of the standard sample is the same as the feature to be measured in the sample. The structural position is the same, and accurate size information cannot be obtained

[0005] In addition, X-ray projection measurement is a two-dimensional plane measurement method, and the actual samples are all three-dimensional objects, which have a certain distribution range in the direction of the X-ray measurement optical axis, which leads to images of different sections of the sample in the direction of the measurement optical axis Due to different geometric magnification ratios, it is difficult to obtain the exact size of the feature structure to be measured inside the sample

Images