| 摘要 |
PURPOSE:To provide a computer tomography method for a plane sample, ensuring freedom from an influence due to the absorption rate of a printed circuit board outside an interest region, and further ensuring less image deterioration respectively at the time of reforming a tomography image for the interest region of a plane sample such as a printed circuit board. CONSTITUTION:In a computer tomography method for a plane sample, an X-ray is cast perpendicularly at a sample 24, and an absorption rate distribution u (x) is obtained. The center of rotation (0, 0) and an interest region (+ or -alpha) for reforming an image are thereby set to obtain projection data f (x, theta). Regarding the direction of the obtained projection data f (x, theta), an absorption rate u (x, theta) outside the interest region is obtained from the expression 1 mentioned below, on the basis of the thickness information (h), projection angle information theta, and the foregoing absorption rate distribution u (x). In addition, a corrected projection data f' is obtained from the expression 2 mentioned below, on the basis of the projection data and absorption rate (u) outside the interest region, thereby reforming an image. The expression 1 is established as u (x, theta)= B (u (x; x<-alpha, x>alpha), thetaphi) where phi is a radiation angle, while the expression 2 is established as f' (x, theta)=f (x, theta)-u (x, theta). |
