The reaction of oxygen with silicon tetrachloride (SiCl₄) and other glass-forming chemicals is the basis for the preparation of optical fiber preforms by the modified chemical vapor deposition (MCVD) process. Control of the concentration of the gas phase reactants is important for fabricating a preform core with the desired composition and refractive index profile. An acoustic time-of-flight (ATOF) method has been used to determine the concentration and evaluate the stability of the precursor delivery system used in the MCVD process. The measurement technique is based on accurate determination of the speed of sound which is dependent on the concentration of the binary mixture. Highly precise measurements for SiCl₄ and GeCl₄ have been obtained for a variety of oxygen carrier gas flow rates. The results obtained by the ATOF method agree within +/- 1% of the values obtained by direct gravimetric calibrations. The utility of ATOF for calibrating chemical reagent delivery systems is confirmed experimentally.

Date Published: 30 April 1993
PDF: 12 pages
Proc. SPIE 1796, Chemical, Biochemical, and Environmental Fiber Sensors IV, (30 April 1993); doi: 10.1117/12.143540

Published in SPIE Proceedings Vol. 1796:
Chemical, Biochemical, and Environmental Fiber Sensors IV
Robert A. Lieberman, Editor(s)