Optical multichannel analyzer constructed with 4400 system for glass surface and thin film measurement

Abstract

A new scheme of optical multichannel analyzer is developed based on Model 4400 Signal Detection and Analysis System. The scheme consists of an optical signal source, a photodiode array and Model 4400 Signal Detection and Analysis System. The signal source provides varies light intensity distribution from optical system. The photodiode array transforms spatial distribution of light intensity into time dependence of electric current intensity. Model 4400 Signal Detection and Analysis System carries out signal processing and analysis through boxcar, keyboard control and advanced microprocessor. With this scheme, the spatial distribution of laser light-intensity was described and the relevant parameters such as beam waist radius of Gaussian distribution were obtained. Further, the optical parameters of the plane glass surface and PMTES thin films were obtained by p-polarized reflectance method. By measuring the angle distribution of reflectance ratio and fitting the results with theoretical data, the optical parameters can be obtained easily. Experimental results indicate that the refractive index and extinction coefficient of glass surface layers decrease exponentially with the thickness of glass layer. Also the optical parameters of PMTES films with the presented scheme have been measured, and the experimental results coincide well with theoretical simulation only if the glass surface layers are considered. Due to the introduction of digital averaging technique in 4400 System, the sampling signals with higher signal-to-noise ratio are acquired, and the presented scheme has higher measurement precision, which is very suitable to temporal-spatial transform and analysis of optical field and precise measurement of surface and film system.