Method and apparatus for determining the position of an x-ray cone beam produced by a scanning electron beam

• US 7,023,950 B1
• Filed: 02/09/2005
• Issued: 04/04/2006
• Est. Priority Date: 02/11/2004
• Status: Expired due to Fees

• Current Assignee: Martin Annis
• Original Assignee: Martin Annis
• Inventors: Annis, Martin
• Primary Examiner(s): Ho, Allen C.
• Application Number:
  US11/054,596
• Time in Patent Office: 419 Days
• Field of Search: 378/2, 378/9, 378/10, 378/12, 378/57, 378/98.6, 378/119, 378/124, 378/137, 378/143, 378/146, 378/207
• US Class Current: 378/2
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/044 using laminography or tomosynthesis
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: H01J 2235/086 Target geometry
• CPC Class Codes: H01J 35/30 by deflection of the cathode ray

Abstract

A Laminography system with x-ray source and a detector assembly. The x-ray source uses a narrow, deflected pencil beam to scan to a linear target. An x-ray cone beam detected by the detector assembly is produced where the electron beam strikes the target. The target is a layer of high-emitting material that is partitioned with narrow regions of low-emitting material, where the low flux intensity is sufficiently low to be easily distinguished from the flux intensity of the high-emitting material. The target may be constructed as a discontinuous layer of high-emitting material applied to a substrate of low-emitting material, or as strips of low-emitting material applied to a continuous layer of high-emitting material.

Claims

1. A system for inspecting an object with an improved method of locating the position of an x-ray source, said system comprising:

(a) an electron source that provides a pencil beam of electrons;

(b) an electromagnet assembly that receives said pencil beam of electrons and that directs said pencil beam to form a scanning beam;

(c) a linear target that is struck by said scanning beam along an x-ray source line, said target having high-emitting regions that produce high-flux-intensity x-ray cone beams from cone beam sources in said x-ray source line when struck by said scanning beam and low-emitting regions that produce low-flux-intensity x-ray cone beams from cone beam sources in said x-ray source line when struck by said scanning beam, said high flux intensity being distinguishable from said low flux intensity, and said low-emitting regions having known locations;

(d) an assembly of x-ray detectors that receive said high-flux-intensity cone beams and said low-flux-intensity cone beams and that is located in a plane that includes the x-ray source line, said assembly of detectors and said x-ray cone beam sources forming a moving fan beam of detected x-rays, and said assembly of detectors providing signals corresponding to the flux intensity of said detected x-rays; and

(e) a processor that receives said signals and determines the precise positions of said x-ray cone beam sources at measured time intervals by interpolating between the times corresponding to low-emitting regions.

2. The system of claim 1 further comprising a slit collimator that receives said x-ray cone beams and generates a fan beam in a plane directed to said assembly of x-ray detectors.

3. The system of claim 1 wherein said object is between said target and said assembly of x-ray detectors.

4. The system of claim 1 wherein said target is composed of discrete regions of high-emitting material on a low-emitting substrate.

5. The system of claim 1 wherein said target is composed of low-emitting material applied to high-emitting material at said low-emitting regions.

6. The system of claim 1 wherein said low-emitting regions are substantially perpendicular to said scanning beam line.