Dual-beam multiple-wavelength light transmittance measurement for particle sizing in rocket motor plumes

A multiple-wavelength light transmittance measurement system previously used in a laboratory environment to study particles in solid rocket propellant exhaust plumes was modified for use in the field, where high levels of vibration can degrade the accuracy of data. The system was converted from a single light beam configuration to a dual beam configuration which was capable of obtaining a complete set of 1024 reference and scene measurements in 10.0 ms. Modifications included designing, building and testing a new analog-to-digital data converter trigger circuit, and a rotating-wheel light chopper. Optical components including beam splitters, lenses, and a fiber optic cable were installed, and existing data collection system software was modified. The new system was tested by measuring soot from an oxyacetylene torch to prove the design concept. Test results and system performance were documented. Recommendations for further modifications, improvements and applications are presented.
http://archive.org/details/dualbeammultiple1094539851
Lieutenant Commander, United States Navy
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