System and method for manipulating an object for imaging

{
  "publication_number": "US9921400B2",
  "country": "US",
  "kind": "B2",
  "title": "System and method for manipulating an object for imaging",
  "abstract": "A method for manipulating an object for imaging by an imaging device includes the steps of rotating the object about a rotation axis into a plurality of angular positions; capturing an image of the object at each of the plurality of angular positions; and determining a respective translation required of the object for the plurality of angular positions, the translation being along a plane substantially orthogonal to the rotation axis; wherein the respective translation is arranged to align the object to the rotation axis so as to maintain the object within a field of view of the imaging device.",
  "claims": [
    "1. A method for manipulating an object for imaging by an imaging device, comprising the steps of: (a) rotating the object about a rotation axis into a plurality of angular positions comprising a first angular position, a second angular position and a third angular position; (b) capturing an image of the object at each of the plurality of angular positions; (c) determining a respective translation required of the object for the plurality of angular positions, the translation being along a plane substantially orthogonal to the rotation axis; the respective translation being arranged to align the object to the rotation axis so as to maintain the object within a field of view of the imaging device, the determination step comprises: mapping a position of the object in an object space to a position of the object on the image in an image space; and determining a translation required of the object in the object space based on a position difference of the object in the images in the image space; and (d) comparing the position difference with an error threshold ϵ mag to determine if translation determined would be sufficient to move the object into an optimized position.",
    "2. The method in accordance with claim 1, wherein the rotation axis is substantially perpendicular to an imaging axis of the imaging device, and the plane is substantially parallel to the imaging axis of the imaging device.",
    "3. The method in accordance with claim 1, an angular separation between the first and second angular positions is the same as an angular separation between the second and third angular positions.",
    "4. The method in accordance with claim 1, wherein the error threshold ϵ mag is defined by ɛ mag = u Ra ⁢ TP wherein u is a dimension of a pixel in the image space; Ra is an indicator of a fluctuation tolerance of the object in the field of view of the imaging device; and TP is a height of the image measured in the image space.",
    "5. The method in accordance with claim 1, whereupon determining that the position difference is larger than the error threshold ϵ mag: translating the object to a new position based on the determined translation; and repeating steps (a) to (c) for the same angular separation with the object translated to the new position.",
    "6. The method in accordance with claim 1, whereupon determining that the position difference is smaller than the error threshold ϵ mag: a. repeating steps (a) to (c) for one or more further angular separations.",
    "7. The method in accordance with claim 6, wherein the angular separation is smaller than the one or more further angular separations.",
    "8. The method in accordance with claim 6, wherein the angular separation and the one or more further angular separations are each less than 90 degrees.",
    "9. The method in accordance with claim 6, further comprising: adjusting a magnification of the imaging device to a second value after repeating steps (a) to (c) for the one or more further angular separations.",
    "10. The method in accordance with claim 9, wherein the second value of the magnification equals to a working magnification of the imaging device.",
    "11. The method in accordance with claim 1, further comprising: adjusting a magnification of the imaging device to a first value prior to step (a).",
    "12. The method in accordance with claim 11, wherein the first value is smaller than a working magnification of the imaging device.",
    "13. The method in accordance with claim 1, further comprising the step of: (e) imaging the object at different angular positions by rotating and translating the object based on the determined translation at the plurality of angular positions.",
    "14. The method in accordance with claim 13, wherein the object is rotated about the rotation axis in step (e) for at least one revolution so as to obtain a plurality of images of the object at different angular positions.",
    "15. The method in accordance with claim 13, wherein the object is rotated continuously about the rotation axis in step (e).",
    "16. The method in accordance with claim 13, wherein the translation and rotation of the object are independent.",
    "17. The method in accordance with claim 13, wherein the imaging of the object in step (e) is performed under a working magnification of the imaging device.",
    "18. The method in accordance with claim 1, wherein the object includes one or more micro- or nano-structures to be imaged by the imaging device.",
    "19. The method in accordance with claim 1, further comprising the step of: measuring rotational properties of the object as the object is being rotated and translated based on the determined translation at each of the different angular positions.",
    "20. The method in accordance with claim 1, wherein the imaging device is an optical microscope or an electron microscope.",
    "21. A system for manipulating an object for imaging by an imaging device, comprising: a translation and rotation assembly arranged to rotate the object about a rotation axis and to translate the object along a plane substantially orthogonal to the rotation axis; a controller arranged to control the translation and rotation assembly and to control operation of an imaging device; wherein the controller is arranged to operate the translation and rotation assembly and the imaging device to perform the method in accordance with claim 1.",
    "22. The system in accordance with claim 21, wherein the rotation axis is substantially perpendicular to an imaging axis of the imaging device, and the plane is substantially parallel to the imaging axis of the imaging device.",
    "23. The system in accordance with claim 21, wherein the imaging device is an optical microscope or an electron microscope.",
    "24. The system in accordance with claim 21, wherein the translation and rotation assembly has three or more degree of freedom.",
    "25. The system in accordance with claim 21, wherein the translation and rotation assembly comprises a translation module and a rotation module that can be operated independently.",
    "26. A method for manipulating an object for imaging by an imaging device comprising the steps of: (a) rotating the object about a rotation axis into a plurality of angular positions comprising a first angular position, a second angular position, and a third angular position; (b) capturing an image of the object at each of the plurality of angular positions; (c) determining a respective translation required of the object for the plurality of angular positions, the translation being along a plane substantially orthogonal to the rotation axis; the respective translation being arranged to align the object to the rotation axis so as to maintain the object within a field of view of the imaging device, the determination step comprising: mapping a position of the object in an object space to a position of the object on the image in an image space; and determining a translation required of the object in the object space based on a position difference of the object in the images in the image space; wherein the position of the object in the object space [X N, Y N, Z N] T is mapped to the position of the object on the image in the image space [X M,Y M,Z M] T based on: [x M y M z M] = 1 u ⁢ RX ⁡ (θ x) · RY ⁡ (θ y) · RZ ⁡ (θ z) ⁡ [x N y N z N] + T MN wherein T MN = [x T y T z T], RX ⁡ (θ x) = [1 0 0 0 cos ⁢ ⁢ θ x sin ⁢ ⁢ θ x 0 - sin ⁢ ⁢ θ x cos ⁢ ⁢ θ x], ⁢ RY ⁡ (θ y) = [cos ⁢ ⁢ θ y 0 - sin ⁢ ⁢ θ y 0 1 0 sin ⁢ ⁢ θ y 0 cos ⁢ ⁢ θ y], RZ ⁡ (θ z) = [cos ⁢ ⁢ θ z sin ⁢ ⁢ θ z 0 - sin ⁢ ⁢ θ z cos ⁢ ⁢ θ z 0 0 0 1], ⁢ θ x, θ y and θ z are a rotation angle of the object space relative to the image space about rotation axes X M, Y M and Z M in the image space respectively; [X T, Y T, Z T] T is a translation between the object space and the image space, and u is a dimension of a pixel in the image.",
    "27. A method for manipulating an object for imaging by an imaging device comprising the steps of: (a) rotating the object about a rotation axis into a plurality of angular positions comprising a first angular position, a second angular position, and a third angular position; (b) capturing an image of the object at each of the plurality of angular positions; (c) determining a respective translation required of the object for the plurality of angular positions, the translation being along a plane substantially orthogonal to the rotation axis; the respective translation being arranged to align the object to the rotation axis so as to maintain the object within a field of view of the imaging device, the determination step comprising: mapping a position of the object in an object space to a position of the object on the image in an image space; and determining a translation required of the object in the object space based on a position difference of the object in the images in the image space; wherein the translation required of the object for a particular angular separation is determined based on: [x n ⁢ ⁢ 0 y n ⁢ ⁢ 0 z n ⁢ ⁢ 0] = u ⁡ [Δ ⁢ ⁢ x f + Δ ⁢ ⁢ x b 2 ⁢ ⁢ cos ⁢ ⁢ α - 2 Δ ⁢ ⁢ x f - Δ ⁢ ⁢ x b 2 ⁢ ⁢ sin ⁢ ⁢ α 1 u ⁢ z n ⁢ ⁢ 0] wherein [X n0, Y n0, Z n0] T is a coordinate of a to-be-aligned point of the object in object space; μ is a dimension of a pixel in the image space, Δx f is a position difference of the object in the image of the first angular position and in the image of the second angular position; Δx b is a position difference of the object in the image of the second angular position and the object in the image of the third angular position; and α is an angular separation between the first and second angular positions."
  ],
  "description_excerpt": "The present invention relates to the field of imaging, and particularly, although not exclusively, to a system and method for aligning an object to a field of view of the imaging device for imaging an object being rotated at different angular positions.\n\nImaging of objects with high magnification and large view area at small scale is desirable in many applications, such as micro defect detection, precise manipulation, and in-situ material characterization. Microscopic imaging techniques are one of the suitable techniques for these applications. This is because microscopic imaging apparatuses can image micro- or nano-sized sample objects with resolution up to nanometer scale, and by moving the sample stage and image the sample object at different positions on the same plane, a large microscopic view area can be obtained.\n\nDespite these advantages, most of the existing microscopy systems can only image from one fixed direction. And as a result, some other surfaces of the sample object are not imaged, which results in loss of information. More importantly, the information obtained from a single surface is usually not complete and hence cannot fully reflect the overall properties of the object.",
  "cpc": [
    "G02B 21/26",
    "B25J 9/1697",
    "G05B 2219/40005",
    "H01J 2237/20214",
    "H01J 2237/20221",
    "H01J 2237/2611",
    "H01J 37/20",
    "H01J 37/26"
  ],
  "ipc": [
    "G02B 21/26",
    "H01J 37/20",
    "H04N 7/18"
  ],
  "assignees": [
    "City University of Hong Kong CityU"
  ],
  "inventors": [
    "Yajing Shen",
    "Wenfeng Wan",
    "Lijun Zhang"
  ],
  "filing_date": "2015-12-17",
  "publication_date": "2018-03-20",
  "grant_date": "2018-03-20",
  "priority_date": "2015-12-17",
  "application_number": "US-201514972318-A",
  "family_id": "59066813",
  "cited_by_count": 0,
  "citations": [
    "US4833698A",
    "US7130375B1",
    "US7400704B1",
    "US20160266363A1",
    "US20160363543A1"
  ]
}