Development And Application Of A Broadband Imaging Mueller Matrix Ellipsometer

Imaging ellipsometer is a new type of ellipsometry measurement instrument that has attracted a large number of researches on the fields of two-dimensional materials and micronano manufacturing due to its combination of thin film measurement accuracy of ellipsometry and high spatial resolution of microscopic measurement.The research on imaging ellipsometers and similar equipment began in the 1980 s,and has achieved rich results in nearly 40 years of research.There is a general problem on the existing imaging ellipsometers that the measurement band is limited to the visible light band,which hampers the further application of imaging ellipsometers in materials science.Therefore,this paper intends to develop an imaging Muller matrix ellipsometer that can work in a wide spectral range from ultraviolet to near-infrared,which will provide a way to solve the abovementioned problems.This article first proposes the important significance of developing a broadband Muller matrix imaging ellipsometer because of the dilemma in the field of micro-material measurement research nowadays.On this base,we proposed the design scheme of the broadband Muller matrix imaging ellipsometer with a design spectrum coverage of 300nm-900 nm.Then we completed the optic elements selection and the construction and debugging of the prototype of the instrument according the scheme.The main work and innovations completed in the development process are as follows:(1).Based on the classic dual-rotation modulation model,we designed the polarization modulation system with two driven motor whose ratio of frequency is 5:3.Complete the selection of broadband polarization optic components,and calibrate its polarization characteristics,especially the retardation of the compensator in the design band,to ensure that the polarization measurement optical path is in the best optimizing configuration.(2).Design a unique image-side telecentric microscopic imaging system by combined a reflective objective lens and a broadband achromatic lens.the analysis result of optical performance of the optical path from 280 nm to 900 nm got from Zemax shows a good aberration correction effect within the design band.(3).Design a unique convergent backside reflection beam separation structure and achieve backside reflection beam separated for those transparent substrates with thickness more than 0.6mm.and complete the preliminary analysis of the influence of the small incident light cone angle on the measurement accuracy at the same time.(4).Complete the construction and debugging of the instrument prototype,and use a variety of samples to calibrate and experimentally measure the basic performance of the prototype,including resolution and polarization measurement accuracy,demonstrating the excellent performance of the instrument prototype within the design band.Focusing on these four aspects,this article will systematically elaborate on the design,calibration and experimental debugging of the entire instrument.All of our work will prove the instrument designed in this subject has great potential in the research of two-dimensional materials.