Meaning
Geometric conditions describe the angle at which radiation or light hits a detector when it does not travel parallel to the primary optical axis. In X-ray imaging, off-axis beam inclination occurs because the source is a point and the rays diverge to cover the full area of the detector. This angle increases as the distance from the center of the detector grows, leading to changes in the apparent thickness of the object.
High-precision metrology must account for this tilt to avoid errors in measuring the size of internal features.
Ray Path
Photons traveling at an angle pass through more material than those traveling straight through the center of the sample. Off-axis beam inclination changes the absorption profile and can lead to shading artifacts in the reconstructed volume. Correcting for this path length difference is a standard part of the reconstruction software.
Angle Deviation
Alignment of the source and detector is critical for maintaining a predictable beam geometry. If the detector is tilted relative to the source, the off-axis beam inclination will be asymmetric, making calibration much more difficult. Measurement systems use lasers or mechanical gauges to ensure the components are perfectly squared.
Projection Error
Features located at the edges of the field of view appear distorted compared to those at the center. This distortion caused by off-axis beam inclination can be modeled mathematically to restore the true shape of the part. Failure to apply these corrections results in a loss of dimensional accuracy in the final three-dimensional model.
