Reduced mass flying spot scanner having arcuate scanning lines

• US 5,224,144 A
• Filed: 09/12/1991
• Issued: 06/29/1993
• Est. Priority Date: 09/12/1991
• Status: Expired due to Term

• Current Assignee: American Science and Engineering Incorporated (OSI Systems Incorporated)
• Original Assignee: American Science and Engineering Incorporated (OSI Systems Incorporated)
• Inventors: Annis, Martin
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US07/758,101
• Time in Patent Office: 656 Days
• Field of Search: 378/4, 378/57, 378/86, 378/87, 378/62, 378/44, 378/146, 378/901, 378/89, 378/19, 378/147, 378/156
• US Class Current: 378/146
• CPC Class Codes: G01N 23/04 and forming images of 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: G21K 1/04 using variable diaphragms, shutters, choppers
• CPC Class Codes: G21K 1/043 changing time structure of beams by mechanical means, e.g. choppers, spinning filter wheels

Abstract

A method and apparatus for creating image information for objects inspect with penetrating radiation which utilizes a flying spot scanner of reduced mass. Objects are scanned with penetrating radiation along curved scan lines. The flying spot scanner which effects such scanning has a stationary absorber plate having a fixed slit in it which is curved, as well as a chopper wheel having radially oriented slits. As the chopper wheel rotates, the radially oriented slits traverse the projection of the radiation passing through the fixed slit, and because this slit is curved, the radial slits may be of reduced length, and the chopper wheel may be of reduced mass. The detected radiant energy is divided into pixels, and the pixels are addressed to a utilization means such as a memory or a display in such manner that the pixels which correspond to a scan line of the object define a curved line in the utilization means which has the same shape as the curved scanning line.

Claims

1. A method of creating image information corresponding to an object which is inspected with penetrating radiation comprising,

scanning said object with a flying spot of penetrating radiant energy along arcuate lines,

detecting said radiant energy after interaction with said object, and as a result of said detecting, forming a detection signal,

producing pixels from said detection signal, wherein each pixel corresponds to an elementary frontal area of the object, and

feeding said pixels, or signals derived therefrom, to a utilization means in such manner that the pixels which correspond to a scan line of said object define an arcuate line in the utilization means.

2. The method of claim 1 wherein said utilization means comprises a memory.

3. The method of claim wherein said utilization means comprises a display device.

4. An apparatus for creating image information corresponding to an object which is inspected with penetrating radiant energy, comprising,

means for scanning said object with a flying spot of penetrating radiant energy along arcuate lines,

radiant energy detecting means for receiving said radiant energy after interaction with said object and providing at least one detection signal,

means for producing pixels from at least one detection signal, wherein each pixel corresponds to an elementary frontal area of the object, and

means for feeding said pixels, or signals derived therefrom, to a utilization means.

5. The apparatus of claim 4 wherein said means for feeding said pixels or signals derived therefrom to a utilization means comprises means for feeding said utilization means in such manner that the pixels which correspond to a scan line of said object define an arcuate line in said utilization means.

6. The apparatus of claim 5 wherein said radiant energy detecting means comprises a transmission detector having a shape which corresponds to said arcuate lines.

7. The apparatus of claim 5 wherein said radiant energy detecting means comprises a detector of scattered radiation.

8. The apparatus of claim 5 wherein said means for scanning said object with a flying spot of radiant energy comprises a source of penetrating radiation, an absorber plate having a fixed slit in the shape of an arc, and an absorbing chopper wheel having at least one radially oriented slit.

9. The apparatus of claim 8 wherein said means for scanning said object with a flying spot of radiant energy further comprises means for effecting relative translation movement between said and object and said fixed slit in said absorber plate.

10. The apparatus of claim 5 wherein said utilization means comprises a storage means.

11. The apparatus of claim 5 wherein said utilization means comprises a display means.

12. An apparatus for scanning a object with penetrating radiation, comprising,

a source of penetrating radiation,

an absorber plate having a fixed, arcuate slit therein,

a chopper wheel made in part of radiation absorbing material, the chopper wheel having at least one radially oriented slit therein,

the source of penetrating radiation, the absorber plate, and the chopper wheel being positioned with respect to each other so that radiation from the source passes through the fixed slit in the absorber plate and is incident upon the chopper wheel, and

means for rotating the chopper wheel.

13. The apparatus of claim 12 wherein the chopper wheel has an annular ring shaped portion of radiation absorbing material, and the radial slits are in such portion.

14. The apparatus of claim 13 wherein the radiation from the source which passes through the fixed slit in the absorber plate is projected substantially wholly upon the annular ring shaped absorbing portion of the chopper wheel.

15. The apparatus of claim 12, further comprising means for effecting relative translation motion between said object and said fixed slit in said absorber plate.

16. A method of creating image information corresponding to an object which is inspected with penetrating radiation comprising,

scanning said object with a flying spot of penetrating radiant energy along curved scanning lines,

detecting said radiant energy after interaction with said object, and as a result of said detecting, forming a detection signal,

producing pixels from said detection signal, wherein each pixel corresponds to an elementary frontal area of the object, and

feeding said pixels, or signals derived therefrom, to a utilization means in such manner that the pixels which correspond to a scan line of said object define a curved line in said utilization means which has the same shape as said curved scanning lines.