与消光式兼容的光度椭偏仪的原理

在PQSA式消光型椭偏仪基础上,把原来方位固定的1/4波片改为旋转波片就可以构成与消光式兼容的新型光度椭偏仪。本文讨论了这种光度椭偏仪的工作原理和计算公式。理论分析指出,这是一种完全的椭偏仪,能唯一地确定的符号,并在测量线偏光的时精度不会下降。文中还报告了进行原理性实验的结果。     

A universal ellipsometer

This paper describes the design of an instrument which can be used for studies of optical rotation, circular dichroism and conventional ellipsometry. The main features are that it is automatically recording and, unlike other instruments, allows the azimuth and ellipticity to be measured simultaneously on a twin channel recorder. The recorder has a common chart drive which is synchronised to a scanning monochromator that covers a wide wavelength range.     

多功能椭偏测厚仪

研究成功一台变入射角反射式消光法多功能智能椭偏测厚仪。实验表明 :仪器的测厚准确度为± 0 1nm ;椭偏参数Ψ和Δ的测量重复性精度分别为± 0 1°和± 0 3° ,适用于纳米级薄膜厚度和折射率的测量     

A rotating-compensator fourier ellipsometer

A new digital Fourier ellipsometer is described which employs a rotating compensator and a fixed analyzer to measure the polarization of light reflected from the sample. This technique combines the advantages of null ellipsometry and previously reported rotating- analyzer Fourier ellipsometry (RAE) in that it is fast, precise, has data processing flexibility and operates at high detected levels, but removes the handedness ambiguity present in RAE. The instrument may be called a Fixed-Analyzer, Rotating-Compensator Ellipsometer, but in the interest of brevity the authors have chosen the acronym RCE.     

Accurate heterodyne interferometric ellipsometer

We describe a heterodyne interferometric ellipsometer which requires only a single reflection from the sample surface. A simple arrangement is described that enables a reference beam to be created in one arm of a modified Mach–Zehnder interferometer such that the p- and s-polarisations in this arm have a common phase and fixed relative amplitude, irrespective of the sample. When this beam is recombined interferometrically with the measurement beam, the spatially separated p and s fringes have an amplitude ratio and relative phase that are directly proportional to tanψ and Δ, respectively. Adjusting the azimuthal angle of the input linear polarisation allows both ψ-tracking to be implemented and error reduction through averaging. Measurements made with this instrument of a native oxide layer on a silicon substrate are in excellent agreement with those obtained using a commercial ellipsometer.     

Polarization modulation imaging ellipsometer

The polarization modulation technique was successfully combined with parallel synchronous detection using a switching light source and a CCD camera to realize full-frame measurement of ellipsometric parameters. The detected thickness of a monolayer film of n-octadecylsiloxane agreed well with theoretical and reported experimental values. The thickness resolution for imaging and the temporal noise in parallel thickness measurements were smaller than +/-0.1 nm and smaller than +/-0.02 nm, respectively.     

An automated scanning ellipsometer

An ellipsometer with no moving parts has been designed with response only limited by the photo detectors and readout instrumentation. The simplicity of the design makes it conducive to miniaturization and its fast response for rapid scanning of surfaces for mapping purposes.     

NIRSE: Normal-incidence rotating-sample ellipsometer

We describe a normal-incidence rotating-sample ellipsometer (NIRSE) which is capable of measuring the ratio of the complex amplitude reflection coefficients of an anisotropic sample for incident light that is linearly polarized along two orthogonal principal axes in its surface. In the NIRSE, is derived from the normalized amplitudes of the Fourier components of a photoelectric signal at double and four times the angular frequency of sample rotation. The application of PIE (perpendicular-incidence ellipsometry) to anisotropic film-substrate systems is also discussed.     

Dual-frequency paired polarization phase shifting ellipsometer

A novel dual-frequency paired polarization phase shifting ellipsometer (DPPSE) is proposed and experimentally demonstrated. It combines the features of the phase shifting interferometer and common-path polarized heterodyne interferometric ellipsometer where the ellipsometric parameters (EP) of a specimen are measured accurately. The experimental results verify that DPPSE is capable of determining the full dynamic range of EP. In addition, the properties of dual-frequency paired linearly polarized laser beam in DPPSE perform in common phase noise rejection mode. It is insensitive to environmental disturbance and laser frequency noise. The capability of DPPSE to perform higher accuracy EP measurement than conventional ellipsometer is verified according to error analysis.     

椭偏仪中ES=EP的椭圆偏振光

指出一些实验教材中关于椭偏仪实验原理的一个不确切提法,并给出了详细的分析。     

遗传算法在椭圆偏振测量中的应用

详细介绍了椭圆偏振法测量的基本原理和椭偏函数方程的建立 ,将遗传算法引入到椭偏法测试薄膜的折射率和厚度的计算中 ,改善了计算的收敛性并提高收敛速度。给出了计算程序流程图 ,重点分析了各遗传算子的设计。     

高校椭偏测厚实验的计算机辅助教学

分析了高校椭偏测厚实验中存在的问题，成功研制出具有教学特点的多功能智能椭偏测厚仪和编制了一套该实验的CAI课，实验表明：椭偏测厚实验的计算机辅助教学效果良好。     

提高旋转检偏器式椭偏仪准确度的方法

本文分析了最常见的影响旋转检偏器式椭偏仪准确度的两个因素.提出了改进的测量方法和测量结果的修正公式,提高了测量准确度并为实验所证实.     

Development and construction of rotating polarizer analyzer ellipsometer

A detailed mathematical derivation and an experimental characterization of one to two ratio rotating polarizer analyzer ellipsometer (RPAE) are presented. The alignment, calibration, and testing of reference samples are also discussed. The optical properties of some known materials obtained by the proposed ellipsometer will be shown and compared to accepted values. Moreover, the constructed ellipsometer will be tested using two ellipsometry standards with different thicknesses.     

Optical Security System using Phase-based Virtual Image and Interferometer

An improved optical security system is proposed based on three phase-encoded images and the principle of interference. This optical system consists of one phase-encoded virtual image to be encrypted and two phase-encoded images, encrypting image and decrypting key. The proposed encryption is performed by the multiplication of an encrypting image and a phase-encoded virtual image which does not contain any information from the decrypted (original) image. Therefore, even if an unauthorized user steals and analyzes the encrypted image, he cannot reconstruct the required image. This virtual image protects the original image from counterfeiting and unauthorized access. Optical experiments show the proposed method is a very useful optical security system.     

Practical limitations to accuracy in a nulling automatic wavelength-scanning ellipsometer

The limits of accuracy in an automatic wavelength-scanning ellipsometer are defined on the basis of measured mechanical properties of the instrument and the geometrical and optical defects of the optical components. A computational procedure is described for obtaining accurate Δ and ψ values by using a matrix model of the instrument, and the areás in which the greatest improvements in accuracy can be achieved are identified.     

A high precision,polychromatic, automatic ellipsometer

The design and performance of a versatile, high precision, automatic ellipsometer, which follows rapid changes in surface properties, scans through the entire visible spectrum and through angles of incidence between 50° and 89°, is described. The state of polarization of the light beam is phase and amplitude modulated by means of two Faraday modulators working at a single frequency but in quadrature. Out-of-balance error signals are electronically processed and applied to a servodrive system which rotates the polarizing elements to the null positions. The angular positions of the prisms are measured by means of moiré fringe-counting systems which have digital displays reading to 0.001° over a range of 360°. The absolute accuracy of measurement of Δ and ψ, once all effects of intrinsic component imperfections and misalignments have been minimised, is better than ±0.013° in ψ and ±0.014° in Δ. The ellipsometer has been shown to work satisfactorily for a wide range of surface problems and in particular for surfaces with reflectivities as low as 0.001. The mechanical construction of the ellipsometer allows simultaneous movement of the two optical arms in opposite directions hence allowing a change in angle of incidence to be effected without any sample realignment. The ellipsometer has been designed with a sufficiently large sample space to allow the inclusion of bulky environmental chambers such as cryostats or vacuum systems and may be used to examine either vertical or horizontal surfaces.     

Rotating polarizer analyzer ellipsometer with a fixed compensator

Recently, a rotating polarizer analyzer ellipsometer (RPAE) in which the two optical elements rotate in opposite directions with the same angular speed has been proposed. Calculated optical constants of some materials obtained from this ellipsometric configuration were in good agreement with published values except in the low photon energy regime. We here improve the structure by adding a fixed compensator after the rotating polarizer. The optical constants of c-Si calculated from the noisy signal in the low energy regime show a high reduction in the percent error when compared to that obtained from the previous structure that does not contain the fixed compensator.