Diseño y construcción experimental de un sistema de caracterización óptica de materiales a bajas temperaturas

Abstract

As is known, the optical properties of materials can change as a function of temperature [1,2]. Therefore, and thinking about the configuration of a robust laboratory of optical characterization in the Department of Physics of the Universidad de los Andes, the design and construction of an optical characterization system for materials at low temperatures is presented in this paper. In particular, it consists of a spectral reflectometer integrated with a commercial optical cryostat. The built-in system allows to lower the temperature up to 3.7 K and the light source offers a spectrum that varies between 300 to 1100 nm and is filtered by means of a monochromator. In the experimental setup, the light coming from a variable wavelength source (monochromator) is led through an optical fiber and directed to a collimating lens and then to a polarizer that selects a linear polarization state. Then, the beam is divided by a beam splitter reflecting a fraction of the incident beam towards a silicon photodiode that detects the reference signal, while the fraction of light transmitted is directed to the sample to be studied. The signal reflected in the sample is collected in a second photodiode identical to the reference one. The signals detected are directed to two voltmeters interconnected with a PC where the acquisition and analysis of data takes place through a program developed in LabVIEW © (Fig.1). The economic resources for the development of this project are given by the Universidad de los Andes.