Optical fiber imaging based tomographic reconstruction of burner flames

This paper presents the design, implementation, and evaluation of an optical fiber imaging based tomographic system for the 3-D visualization and characterization of a burner flame. Eight imaging fiber bundles coupled with two RGB charge-coupled device cameras are used to acquire flame images simultaneously from eight different directions around the burner. The fiber bundle has 30k picture elements and an objective lens with a 92 ^\circ angle of view. The characteristic evaluation of the imaging fiber bundles and the calibration of the system were conducted to ensure the accuracy of the system. A new tomographic algorithm that combines the logical filtered back-projection and the simultaneous algebraic reconstruction technique is proposed to reconstruct the flame sections from the images. A direct comparison between the proposed algorithm and other tomographic approaches is conducted through computer simulation for different test templates and numbers of projections. The 3-D reconstruction of the cross- and longitudinal-sections of a burner flame from image projections obtained from the imaging system was also performed. The effectiveness of the imaging system and computer algorithm is assessed through experimental tests.