Method and apparatus for determining object characteristics
Embodiments of the invention provide a method of determining one or more characteristics of a target object, comprising determining a first phase map for at least a region of a target object based on radiation directed toward the target object, determining one or more further phase maps for a sub-region of the region of the target object, determining a number of phase wraps for the sub-region based on a plurality of phase maps for the sub-region, and determining a characteristic of the region of the target object based on the number of phase wraps for sub-region and the first phase map. Embodiments of the invention also relate to a method of determining one or more characteristics of a target object, comprising determining a phase map for at least a region of a target object based on one or more diffraction patterns, determining a wavefront at a plane of the object based upon the phase map, and determining a refractive property of the object based on the wavefront.
1. A method of determining one or more characteristics of a target object, comprising:
determining a first phase map for at least a region of a target object based on radiation directed toward the target object;
determining one or more further phase maps with a higher resolution than the first phase map for a sub-region of the region of the target object;
determining a number of phase wraps for the sub-region based on the one or more further phase maps for the sub-region; and
determining a characteristic of the region of the target object based on the number of phase wraps for the sub-region and the first phase map.
2. The method of claim 1 , wherein the radiation directed toward the target object has a first wavelength, at least some of the further phase maps being based on radiation directed toward the target object having a wavelength different from the first wavelength.
3. The method of claim 1 , wherein the one or more further phase maps for the sub-region are based on radiation measured at a detector having a higher resolution than for the first phase map.
4. The method of claim 1 , wherein the one or more further phase maps are measured at a detector having an optical arrangement with a higher numerical aperture (NA) than for the first phase map.
5. The method of claim 1 , comprising determining a characteristic of the object in the sub-region based on the plurality of the phase maps.
6. The method of claim 1 , wherein the step of determining one or more further phase maps for the sub-region of the region of the target object comprises determining a plurality of further phase maps for the sub-region.
7. The method of claim 1 , wherein the characteristic of the sub-region is determined based upon a synthetic phase change.
8. The method of claim 1 , comprising determining an average characteristic for the sub-region based upon the plurality of phase maps for the sub-region.
9. The method of claim 5 , comprising determining a number of phase wraps for each of the plurality of further phase maps.
10. The method of claim 6 , wherein the number of phase wraps for the sub-region is determined based upon the number of phase wraps for each phase map for the sub-region and one or more predetermined criteria.
11. The method of claim 1 , comprising determining a background characteristic based upon the plurality of phase maps.
12. The method of claim 8 , wherein a portion of the plurality of phase maps extend beyond a periphery of the object and the background characteristic is determined based the portion.
13. The method of claim 7 , wherein the average characteristic is determined based upon characteristics of a plurality of points within the sub region.
14. The method of claim 1 , comprising determining a characteristic profile of the sub-region.
15. The method of claim 13 wherein the characteristic profile of the sub-region is determining for each of the plurality of phase maps for the sub-region.
16. The method of claim 1 , wherein the first and further phase maps are determined based on a coherent diffractive imaging (CDI) process.
17. The method of claim 15 , wherein the CDI process is based upon a plurality of diffraction patterns at respective probe locations.
18. An apparatus, comprising:
one or more memory devices storing instructions; and
one or more processors coupled to the one or more memory devices and configured to execute the instructions to perform a method comprising:
determining a first phase map for at least a region of a target object based on radiation directed toward a target object;
determining one or more further phase maps with a higher resolution than the first phase map for a sub-region of the region of the target object
determining a number of phase wraps for the sub-region based on the one or more further phase maps for the sub region; and
a characteristic of the region of the target object based on the number of phase wraps for sub-region and the first phase map.
19. A non-transitory computer readable medium comprising instructions that cause a processor to perform a method comprising:
determining a first phase map for at least a region of a target object based on radiation directed toward a target object;
determining one or more further phase maps with a higher resolution than the first phase map for a sub-region of the region of the target object;
determining a number of phrase wraps for the sub-region based on the one or more further phase maps for the sub-region; and
determining a characteristic of the region of the target object based on the number of phase wraps for sub-region and the first phase map.