Electrical & Computer Engineering, Department of


Date of this Version



1995 Society of Photo-Optical Instrumentation Engineers.


OPTICAL ENGINEERING / March 1995 /VoI. 34 No.3 /


Complex index-of-refraction values of RP-1 liquid rocket fuel are reported at laser wavelengths of 0.193 m (ArF excimer), 0.4765 m (argon ion), 0.488 im (argon ion), 0.5145 ji.m (argon ion), 0.532 m (Nd-YAG, frequency doubled), 0.6328 pm (He-Ne), 1 .064 im (Nd-YAG), and 10.5915 im (C02). The imaginary part of the index of refraction (k) is determined by traditional transmission methods. The real part (flr) at the specific laser lines is determined using reflectance measurements, critical-angle measurements, Mueller matrix elements, and Michelson interferometric measurements. Reflectance measurements are used to obtam n at a wavelength of 0.193 m. The critical-angle method is used to determine 'r at 0.4765, 0.488, 0.5145, and 0.532 m: the real part of the refractive index is obtained from Snell's law by measuring the critical angle. The real part of the refractive index at 0.6328 and 1 .064 pm is derived from elements of the Mueller matrix, which are obtained using a TMA Technologies scatterometer. A Michelson interferometer is used to obtain phase shifts in a wedge cell, which are then used to calculate n at 10.5915 m. The need for many methods to measure the complex index of refraction is a result of the large changes in k over the wavelengths of interest.