Designing and building a deflectometry system and evaluating its performance in measuring the dispersion of the linear refractive index of thin scintillatingYAG and quartz crystals

One of the fundamental issues in physics is measuring the refractive index of materials. Knowing the magnitude of the refractive index of a material plays a decisive role in predicting its behavior and the amount of light passing through it. There are different methods for measuring the refractive index. In this work, to measure the refractive index of thin samples, a system based on the optical deflectometry method has been designed and built. The theoretical basis of the work, the effective parameters and the measurement error of the system in measuring the refractive index of thin samples with a thickness of about a few millimeters have been investigated. After optimizing the system, the magnitude of the refractive index of YAG and quartz crystal samples was measured, which are widely used in various applications. Using three lasers of helium-cadmium (blue color, wavelength 442 nm), argon ion (green color, wavelength 514.5 nm) and helium-neon (red color, wavelength 632.8), dispersion of refractive index of these two substances were measured. The measured values for the refractive index in these three wavelengths were 1.44, 1.45, and 1.37 for the quartz sample and 1.81, 1.83, and 1.73 for the YAG crystal sample.