Complex index-of-refraction measurements for RP-1 liquid rocket fuel

摘要

Complex index-of-refraction values of RP-1 liquid rocket fuel are reported at laser wavelengths of 0.193 μm (ArF excimer), 0.4765 μm (argon ion), 0.488 μm (argon ion), 0.5145 μm (argon ion), 0.532 μm (Nd-YAG, frequency doubled), 0.6328 μm (He-Ne), 1.064 μm (Nd-YAG), and 10.5915 μm (CO_2). The imaginary part of the index of refraction (k) is determined by traditional transmission methods. The real part (n_r) at the specific laser lines is determined using reflectance measurements, critical-angle measurements, Mueller matrix elements, and Michelson in-terferometric measurements. Reflectance measurements are used to obtain n_r at a wavelength of 0.193 μm. The critical-angle method is used to determine n_r at 0.4765, 0.488, 0.5145, and 0.532 μm: 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 μm 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_r at 10.5915 μm. 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.