Method for detecting an image of an object

• US 5,987,095 A
• Filed: 09/24/1997
• Issued: 11/16/1999
• Est. Priority Date: 10/16/1996
• Status: Expired due to Term

• Current Assignee: Leroy Dean Chapman, William C. Thomlinson, Zhong Zhong
• Original Assignee: Leroy Dean Chapman, William C. Thomlinson, Zhong Zhong
• Inventors: Zhong, Zhong, Chapman, Leroy Dean, Thomlinson, William C.
• Primary Examiner(s): Porta, David P.
• Application Number:
  US08/936,250
• Time in Patent Office: 783 Days
• Field of Search: 378/62, 378/70, 378/71, 378/84, 378/87, 378/37, 378/36, 378/98.12
• US Class Current: 378/70
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G01N 23/201 by measuring small-angle scattering
• CPC Class Codes: G01N 23/207 Diffractometry using detectors, e.g. using a probe in a central position and one or more displaceable detectors in circumferential positions

Abstract

A method for detecting an absorption, refraction and scatter image of an object by independently analyzing, detecting, digitizing, and combining images acquired on a high and a low angle side of a rocking curve of a crystal analyzer. An x-ray beam which is generated by any suitable conventional apparatus can be irradiated upon either a Bragg type crystal analyzer or a Laue type crystal analyzer. Images of the absorption, refraction and scattering effects are detected, such as on an image plate, and then digitized. The digitized images are simultaneously solved, preferably on a pixel-by-pixel basis, to derive a combined visual image which has dramatically improved contrast and spatial resolution over an image acquired through conventional radiology methods.

Claims

1. In a method for detecting an image of an object, wherein an x-ray beam is generated, the improvement comprising:

transmitting the x-ray beam through the object and emitting from the object a transmitted beam;

directing the transmitted beam at an angle of incidence upon a crystal analyzer;

detecting a first image of the object from a diffracted beam emitted from the crystal analyzer at a low rocking curve angle setting of the crystal analyzer;

detecting a second image of the object from a diffracted beam emitted from the crystal analyzer at a high rocking curve angle setting of the crystal analyzer; and

combining the first image and the second image to derive a refraction image and an absolute absorption image of the object.

2. In a method according to claim 1 further comprising:

detecting a third image of the object from a forward diffracted beam image emitted from the crystal analyzer at the low rocking curve angle setting of the crystal analyzer;

detecting a fourth image of the object from a forward diffracted beam image emitted from the crystal analyzer at the high rocking curve angle setting of the crystal analyzer;

determining refraction and absorption effects of the forward diffracted beam at the low rocking curve angle setting and at the high rocking curve angle setting; and

deriving a scatter image of isolated scatter by removing the refraction and absorption effects from the refraction image and the absolute absorption image.

3. In a method according to claim 2 wherein the crystal analyzer upon which the transmitted beams are directed is a Laue type analyzer.

4. In a method according to claim 1 wherein the first image and the second image are exposed on a detector capable of producing a digitized image.

5. In a method according to claim 4 wherein the exposed first image and the exposed second image are digitized.

6. In a method according to claim 5 wherein the digitized images are mathematically combined to form a digitized refraction image and a digitized absolute absorption image.

7. In a method according to claim 6 wherein the digitized actual image is converted to a visual actual image.

8. In a method according to claim 1 wherein the crystal analyzer upon which the transmitted beams are directed is a Bragg type analyzer.

9. In a method according to claim 1 wherein the transmitted beam has an energy level in a range of approximately 16 keV to approximately 25 keV.

10. In a method according to claim 1 wherein the transmitted beam is generated, upstream from the object, from monochromator crystals constructed of silicon with (3, 3, 3) lattice planes.

11. In a method according to claim 1 further comprising increasing a relative intensity of the image of the object by adjusting an angular position of the crystal analyzer.

12. In a method according to claim 11 wherein the angular position of the crystal analyzer is adjusted to be within a rocking curve of the crystal analyzer.

13. In a method according to claim 11 wherein the angular position of the crystal analyzer is adjusted in steps of approximately 1 microradian increments.

14. In a method according to claim 1 wherein a first intensity (I_L) of the combined image of the object is determined at a low rocking curve angle and a second intensity (I_H) of the combined image is determined at a high rocking curve angle.

15. In a method according to claim 14 wherein the first intensity (I_L) and the second intensity (I_H) are used to determine a normal absorption image (I_T) and a refraction angle image (δ

_Z) of the object.

16. In a method according to claim 15 wherein the normal absorption image (I_T) is determined by:

##EQU7## wherein R_L and R_H respectively represent low rocking curve and high rocking curve reflect ivies.

17. In a method according to claim 15 wherein the refraction angle image (δ

_Z) is determined by;

##EQU8## where R_L and R_H respectively represent low rocking curve and high rocking curve reflect ivies.

18. In a method according to claim 15 wherein the combined image at the low rocking angle curve and the combined image at the high rocking curve angle are aligned so that each pixel of each of the combined images is from a same region of the object, and the normal absorption image (I_T) and the refraction angle image (δ

_Z) are determined on a pixel-by-pixel basis.

19. In a method according to claim 1 wherein the x-ray beam is a mono-energetic synchrotron beam.