Dark-field phase contrast imaging

• US 6,870,896 B2
• Filed: 12/28/2001
• Issued: 03/22/2005
• Est. Priority Date: 12/28/2000
• Status: Expired due to Fees

• Current Assignee: Osmic Incorporated
• Original Assignee: Osmic Incorporated
• Inventors: Protopopov, Vladimir V.
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): KEANEY, ELIZABETH MARIE
• Application Number:
  US10/035,025
• Publication Number:
  US 20020136352A1
• Time in Patent Office: 1,180 Days
• Field of Search: 378/36, 378/62, 378/84, 378/85, 378/87, 378/90, 359/618
• US Class Current: 378/36
• CPC Class Codes: G03H 5/00 Holographic processes or apparatus using particles or using waves other than those covered by groups G03H1/00 or G03H3/00 for obtaining holograms; Processes or apparatus for obtaining an optical image from them G03H1/22 takes precedence; construction of electron microscopes H01J37/26; investigating or analysing materials by the use of microwaves G01N22/00, by the use of particles wave or X-rays G01N23/00, G21K7/00
• CPC Class Codes: G21K 2207/005 Methods and devices obtaining contrast from non-absorbing interaction of the radiation with matter, e.g. phase contrast

Abstract

A method of imaging an object that includes subjecting an object to a beam of radiation that is directed along a first direction and analyzing a first portion of the beam of radiation that is transmitted through the object along the first direction so that the intensity of the first portion is suppressed. Analyzing a second portion of the beam of radiation that is refracted from the object. Generating an image of the object based on the suppressed first portion of the beam of radiation and the second portion of the beam of radiation.

Claims

1. An imaging system comprising:

a radiation generator that generates a beam of penetrating radiation along a first direction;

an object that receives said beam of penetrating radiation, wherein a first portion of said beam of penetrating radiation is transmitted through said object along said first direction and a second portion of said beam of penetrating radiation is refracted along a second direction;

an analyzer that receives said first and second portions of said beam of penetrating radiation, said analyzer suppresses the intensity of said first portion of said beam of penetrating radiation and transmits said second portion of said beam of penetrating radiation; and

a detector system that receives from said analyzer said suppressed first portion of said beam of penetrating radiation and said transmitted second portion of said beam of penetrating radiation and generates an image of said object.

2. The imaging system of claim 1, wherein said beam of penetrating radiation is a parallel beam of penetrating radiation.

3. The imaging system of claim 1, wherein said radiation generator comprises an x-ray source that generates a beam of x-rays.

4. The imaging system of claim 2, wherein said radiation generator comprises an x-ray source that generates a beam of x-rays.

5. The imaging system of claim 3, wherein said radiation generator comprises a monochromator that receives said beam of x-rays from said x-ray source and generates a parallel beam of x-rays.

6. The imaging system of claim 4, wherein said x-ray source works in a linear projection mode.

7. The imaging system of claim 1, wherein said object is smaller than said beam of penetrating radiation.

8. The imaging system of claim 1, wherein said analyzer comprises a multi layer mirror.

9. The imaging system of claim 3, wherein said analyzer comprises a multilayer mirror.

10. The imaging system of claim 8, wherein said multilayer mirror comprises alternating layers of materials with large and small atomic numbers, wherein the thicknesses of the alternating layers is varied so as to suppress the intensity of said first portion of said beam of penetrating radiation.

11. The imaging system of claim 10, wherein said material with a large atomic number is tungsten and said material with a small atomic number is boron-carbon.

12. The imaging system of claim 9, wherein said multilayer mirror comprises alternating layers of materials with large and small atomic numbers, wherein the thicknesses of the alternating layers is varied so as to suppress the intensity of said first portion of said x-ray beam.

13. The imaging system of claim 12, wherein said material with a large atomic number is tungsten and said material with a small atomic number is boron-carbon.

14. The imaging system of claim 4, wherein said x-ray source operates in a point projection mode.

15. The imaging system of claim 14, wherein said object moves relative to said detector system.

16. The imaging system of claim 15, wherein said detector system comprises a detector comprising a column of sensitive elements.

17. The imaging system of claim 16, wherein signals from said column of sensitive elements are averaged to obtain an image signal.

18. The imaging system of claim 17, wherein said image signal is represented by the formula:

$v_{\mathrm{kj}}=\frac{1}{m}<br><br>\underset{i=1}{\overset{m}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>u_{\mathrm{ij}}<br><br>\left[\mathrm{\tau <br><br>}<br><br>\left(k-i\right)\right],$

where u,_ij(t) is the signal generated by the sensitive element located at the ith row and jth column of the detector array, τ

is the time interval during which the object is shifted by a distance equal to a single detector element, m is the number of columns of sensitive elements in the detector, k is the image obtained at time t=kτ

.

19. A method of imaging an object, comprising:

subjecting an object to a beam of penetrating radiation that is directed along a first direction;

analyzing a first portion of said beam of penetrating radiation that is transmitted through said object so that the intensity of said first portion is suppressed;

analyzing a second portion of said beam of penetrating radiation that is refracted from said object;

generating an image of said object based on said suppressed first portion of said beam of penetrating radiation and said second portion of said beam of penetrating radiation.

20. The method of claim 19, wherein said beam of penetrating radiation is a parallel beam of penetrating radiation.

21. The method of claim 19, wherein said beam of penetrating radiation comprises x-rays.

22. The method of claim 20, wherein said beam of penetrating radiation comprises x-rays.

23. The method of claim 19, wherein said object does not move during said generating an image.

24. The method of claim 19, wherein said object moves during said generating an image.

25. The method of claim 19, wherein said generating an image comprises averaging signals from a column of sensitive elements of a detector.