Imaging optical arrangement to image an object illuminated by X-rays
An imaging optical arrangement serves to image an object illuminated by X-rays. An imaging optics serves to image a transfer field in a field plane into a detection field in a detection plane. A layer of scintillator material is arranged at the transfer field. A stop is arranged in a pupil plane of the imaging optics. The imaging optics has an optical axis. A center of a stop opening of the stop is arranged at a decentering distance with respect to the optical axis. Such imaging optical arrangement ensures a high quality imaging of the object irrespective of a tilt of X-rays entering the transfer field. The imaging optical arrangement is part of a detection assembly further comprising a detection array and an object mount. Such detection assembly is part of a detection system further comprising a X-ray source.
1. An imaging optical arrangement to image an object illuminated by X-rays, the imaging optical arrangement comprising
an imaging optics to image a transfer field in a field plane into a detection field in a detection plane via an imaging light path,
a layer of scintillator material arranged at the transfer field, and
a stop being arranged in a pupil plane of the imaging optics,
wherein the imaging optics has an optical axis,
wherein a center of a stop opening of the stop is arranged at a decentering distance with respect to the optical axis.
2. The imaging optical arrangement of claim 1 , wherein the decentering distance is at least 10% of a width of the stop opening.
3. The imaging optical arrangement of claim 1 , wherein the stop is mounted on a decentering drive to translate the stop in the pupil plane.
4. The imaging optical arrangement of claim 1 , wherein an object side numerical aperture of the imaging optics which is defined by the stop opening is larger than 0.4.
5. A detection assembly including an imaging optical arrangement of claim 1 , the detection assembly further comprising
a detection array arranged at the detection field of the imaging optics, and
an object mount to hold an object to be imaged via the imaging optics.
6. A detection system including a detection assembly of claim 5 , the detection system further comprising an X-ray source.
7. The detection system of claim 6 , having a lateral displacement drive for relative lateral displacement of the object mount with respect to the X-ray source.
8. The detection system of claim 7 , wherein
a lateral displacement of the X-ray source with respect to the object mount and
the decentering distance of the center of the stop opening with respect to the optical axis of the imaging optics
are balanced such that X-rays entering the transfer field run parallel to chief imaging rays of imaging light within the imaging light path.
9. The detection system of claim 8 , wherein an angle between the X-rays entering the transfer field and the optical axis of the imaging optics is between 0 deg and 80 deg.
10. An X-ray inspection method using a detection system of claim 6 , wherein the decentering distance of the stop opening of the stop is adapted to an angle of an oblique or tilted entry of X-rays to the transfer field of the imaging optics.
11. The imaging optical arrangement of claim 2 , wherein the stop is mounted on a decentering drive to translate the stop in the pupil plane.
12. The imaging optical arrangement of claim 2 , wherein an object side numerical aperture of the imaging optics which is defined by the stop opening is larger than 0.4.
13. The detection assembly of claim 5 , wherein the decentering distance is at least 10% of a width of the stop opening.
14. The detection assembly of claim 5 , wherein the stop is mounted on a decentering drive to translate the stop in the pupil plane.
15. The X-ray inspection method of claim 10 , comprising balancing a lateral displacement of the X-ray source with respect to the object mount and the decentering distance of the center of the stop opening with respect to the optical axis of the imaging optics such that X-rays entering the transfer field run parallel to chief imaging rays of imaging light within the imaging light path.
16. The X-ray inspection method of claim 15 , comprising reading data from a lookup table that stores data with respect to a dependency between actions of the decentering drive and actions of the lateral displacement drive, and
using the data from the lookup table to balance the lateral displacement of the X-ray source with respect to the object mount and the decentering distance of the center of the stop opening with respect to the optical axis of the imaging optics.
17. The X-ray inspection method of claim 15 , wherein an angle between the X-rays entering the transfer field and the optical axis of the imaging optics is between 0 deg and 80 deg.
18. The X-ray inspection method of claim 10 , comprising performing, using a lateral displacement drive, a relative lateral displacement of the object mount with respect to the X-ray source.