Density detection using real time discrete photon counting for fast moving targets

• US 7,045,787 B1
• Filed: 08/09/2001
• Issued: 05/16/2006
• Est. Priority Date: 10/23/1995
• Status: Expired due to Fees

• Current Assignee: Leidos, Inc. (Leidos Holdings, Inc.)
• Original Assignee: Science Applications International Corporation
• Inventors: Shyffer, Ryan, Verbinski, Victor, Smith, Scott, Adams, Jeffrey
• Primary Examiner(s): GAGLIARDI, ALBERT J
• Application Number:
  US09/925,009
• Time in Patent Office: 1,741 Days
• Field of Search: 250/358.1, 250/360.1, 250/359.1, 250/309, 378/57, 378/197, 378/198, 378/51, 378/54, 378/55, 378/62
• US Class Current: 250/358.1
• CPC Class Codes: G01N 23/02 by transmitting the radiation through the material
• CPC Class Codes: G01V 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays
• CPC Class Codes: G01V 5/232 having relative motion between the source, detector and object other than by conveyor G01V5/226 takes precedence

Abstract

A system for detecting and graphically displaying a contents of a fast-moving target object comprises: a radiation source, having a position such that at least a portion of radiation emitted from the radiation source passes through the fast-moving target object, the fast-moving target object having a variable velocity and acceleration while maintaining a substantially constant distance from the radiation source and being selected from the group consisting of: a vehicle, a cargo container and a railroad car; a velocity measuring device configured to measure the variable velocity of the fast-moving target object; a detector array comprising a plurality of photon detectors, having a position such that at least some of the at least a portion of the radiation passing through the target object is received thereby, the detector array having a variable count time according to the variable velocity and a grid unit size; a counter circuit coupled to the detector array for discretely counting a number of photons entering individual photon detectors, the counter circuit measuring a count rate according to a contents within the fast-moving target object; a high baud-rate interface coupled to the counter circuit for sending count information from the counter circuit at a rate fast enough to support real-time data transfer therethrough; and a processor coupled to the velocity measuring device and to the high-baud-rate interface, receiving count information from the high baud-rate interface and generating distortion-free image data in real time as a function of the count information and the variable velocity. A method for using the system is also disclosed.

Claims

1. A linear detector array system for use in a target inspection system for detecting a contents of the target, the linear detector array comprising:

a plurality of vertical rows of staggered detectors including a center vertical row of staggered detectors and one or more side vertical rows of staggered detectors, each of the plurality of vertical rows being vertically staggered from each other vertical row, such that a pitch between any two closest adjacent staggered detectors is smaller than a diameter of the staggered detectors;

a processor comprising an image-generating program, the processor receiving data from each of the one or more side vertical rows and from the center vertical row;

the image-generating program further including;

adjustment means for determining an adjustment for a horizontal displacement k of the one or more side vertical rows from the center vertical row, wherein the adjustment is used to correlate the data from the side vertical rows with data from the center vertical row so as to form undistorted images for multiple planes within the target; and

computing means for determining an image adjustment distance 1 for multiple planes within the target according to a relationship 1=kZ/D, wherein Z is variable and is a distance between a radiation source and each of the multiple planes within the target, and wherein D is a distance between the radiation source and the linear detector array.

2. A method for processing staggered detection data for use in a target inspection system, the method comprising the steps of:

providing a plurality of vertical rows of staggered detectors, each of the plurality of vertical rows being vertically staggered from each other vertical row, such that a pitch between any two closest adjacent staggered detectors is smaller than a diameter of the staggered detectors including;

providing a center vertical row of staggered detectors;

providing one or more side vertical rows of staggered detectors;

providing a processor comprising an image-generating program;

receiving data at the processor from each of the one or more side vertical rows and from the center vertical row;

determining an adjustment for a horizontal displacement k of the one or more side vertical rows in order to correlate the data from the side vertical rows with data from the center vertical row so as to form undistorted images for multiple planes within the target; and

determining an image adjustment distance 1 for multiple planes within the target according to a relationship 1=kZ/D, wherein Z is variable and is a distance between a radiation source and each of the multiple planes within the target, and wherein D is a distance between the radiation source and the linear detector array.

3. The method of claim 2, further comprising:

adjusting the data from the one or more side vertical rows and the center vertical row using the adjustment distance 1 for each of the multiple planes to form undistorted images for each of the multiple rows; and

comparing the undistorted images for each of the multiple planes to determine the location of an object within the target.