A practical method to calibrate the slant angle of central X-ray for laminography scanning system

• Errors of the slant angle of the central X-ray are analyzed for CL reconstruction.
• The projection of a circle locus on the rotary table is proven to be an ellipse.
• A practical feasible realization for the calibration of the slant angle is proposed.

Computed laminography (CL) has a particular function in plate-type structure tomography. For CL reconstruction, slant angle of the central X-ray is an important parameter and must be calibrated accurately. A practical feasible calibration method to determine the slant angle is proposed. According to this method, a spherical phantom is fixed on the rotary table and turns a full 360° rotation. Then, image processing and the least-square fitting are performed to figure out the locus of the projection. Consequently, the slant angle is achieved in accordance with the property of the fitted ellipse. The experimental results prove that this method is easy to implement and meet the inspection requirements.