Automatic particle sizing from rocket motor holograms

Abstract

Microscopic particles within an optical hologram reconstruction have been successfully measured using an image digitizer and a PC/AT computer. The hologram was recorded during a test burn of some solid rocket fuel and captured a 2 in x 2 in volume of burning particles as they lift from the fuel surface during combustion. The computer processes the digitized images using feature identification algorithms and sizing in the feature's horizontal dimension, its vertical dimension and area. The operation of the algorithms have been validated against calibration objects. Statistical tests show that about 1,300 particles from several image frames are required to obtain a representative size distribution. Overlying speckle degrades the resolution of the image and can be reduced by a variety of techniques. The performance of these speckle-reduction techniques has been measured and compared in the areas of speckle reduction, loss of resolution, and processing time. Program sizes and processing times have been compared for both FORTRAN and C language versions of the processing program