Digital filtering and reconstruction of coded aperture images

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:7252975

Tobin, Jr, K W

The real-time neutron radiography facility at the University of Virginia has been used for both transmission radiography and computed tomography. Recently, a coded aperture system has been developed to permit the extraction of three dimensional information from a low intensity field of radiation scattered by an extended object. Short wave-length radiations (e.g. neutrons) are not easily image because of the difficulties in achieving diffraction and refraction with a conventional lens imaging system. By using a coded aperture approach, an imaging system has been developed that records and reconstructs an object from an intensity distribution. This system has a signal-to-noise ratio that is proportional to the total open area of the aperture making it ideal for imaging with a limiting intensity radiation field. The main goal of this research was to develope and implement the digital methods and theory necessary for the reconstruction process. Several real-time video systems, attached to an Intellect-100 image processor, a DEC PDP-11 micro-computer, and a Convex-1 parallel processing mainframe were employed. This system, coupled with theoretical extensions and improvements, allowed for retrieval of information previously unobtainable by earlier optical methods. The effect of thermal noise, shot noise, and aperture related artifacts were examined so that new digital filtering techniques could be constructed and implemented. Results of image data filtering prior to and following the reconstruction process are reported. Improvements related to the different signal processing methods are emphasized. The application and advantages of this imaging technique to the field of non-destructive testing are also discussed.

• Research Organization: Virginia Univ., Charlottesville, VA (USA)
• OSTI ID: 7252975
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
47 OTHER INSTRUMENTATION
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
NEUTRON RADIOGRAPHY
IMAGE PROCESSING
COMPUTER CODES
COMPUTERS
DIGITAL FILTERS
EXPERIMENTAL DATA
IMAGE CONVERTERS
MEASURING INSTRUMENTS
MEASURING METHODS
DATA
IMAGE TUBES
INDUSTRIAL RADIOGRAPHY
INFORMATION
NUMERICAL DATA
PROCESSING
654001* - Radiation & Shielding Physics- Radiation Physics
Shielding Calculations & Experiments
440000 - Instrumentation
440100 - Radiation Instrumentation