Refractive index of NH(4)Cl-H2O as a function of wavelength: the effect of temperature and concentration.

The refractive index of NH(4)Cl-H(2)O solutions has been measured over a wavelength range from 496.5 to 690 nm. The NH(4)Cl concentration was varied from 15 to 30 wt. % over a temperature range from 10 to 35 °C. We obtained mathematical equations relating the refractive index to wavelength, temperature, and concentration using the least-squares method. A knowledge of these properties is important for analyzing and modeling the dendritic growth of this system.

Solidification studies using a confocal optical signal processor.

The development of a confocal optical processing system and its application to a solidifying metal model are reported. This system has been used to acquire image format data from which quantitative temperature and concentration profiles have been measured. Strong agreement is shown to exist between experimental results obtained in this manner and numerical simulations.