The Optical Detection And Data Acquisition System Of Ellipsometer Drived By LabVIEW

Ellipsometry is an advanced method of detecting various optical parameters of materials, which act as a high precision, non-contact, non-destructive optical analysis techniques. The main application of it is the measurements of parameters contains the thickness and refractive index of optical thin film; the dielectric constant and the complex refractive index of material et. The essence of ellipsometry is to express optical parameters as functions of ellipsometric parameters which can be obtained by analyzing the variation of intensity of the reflected light, so then we can solve the equations to get optical parameters we need. Due to difficulties in the mathematical treatment, the theoretical development and application of ellipsometry didn’t going on an expressway until electronic computer came out in1940s. After decades of continuous improvement, ellipsometer becomes full automation, incident angle variable, wavelength variables, which makes ellipsometry been widely used in semiconductor materials, optics, chemistry, biology and medicine.LabVIEW is a system-design platform and development environment for a visual programming language from National Instruments. With abundant functions and drivers invoked by the visualized G language we can control DAQ devices to realize data acquisition, signal control, process synchronization and data processing. It makes possibilities of electrified instrument autocontrol, synchronous data acquisition, exchange and processing, thus widely accepted by industry, academia and research laboratories as a standard for data acquisition and instrument control software.In this article I build a program with Lab VIEW to drive a DAQ card:PCI-6221(from NI as well) activating an RAP type ellipsometer, use a He-Ne laser as light source, together with a precision optical intensity detector made up of a photocell and high accuracy instrumentation amplifier:AD620, realizing an automatic detection of spectrum of the intensity, with which then I obtain the ellipsometric parameters of a Gold-plated plane mirror at the wavelength of632.8nm by photometric ellipsometry. The instrument control, data acquisition and processing are all accomplished by the program built with LabVIEW. And then, with the ellipsometric parameters, I obtain some optical parameters of gold at632.8nm.