基于扫描白光干涉法的表面三维轮廓仪

在强调表面三维形貌测量重要性的基础上 ,介绍了利用扫描白光干涉法测量表面三维微观形貌的原理及三维轮廓仪测量系统的构成。通过给出的几个测量实例 ,反映了该三维轮廓仪的主要特点 ,适合于大范围、高精度、阶梯面的测量。最后分析了影响其测量精度的主要因素。     

Multi-wavelength phase-shifting interferometry for micro-structures measurement based on color image processing in white light interference

Conventional multi-wavelength phase-shifting interferometry utilizes two or three monochromatic light sources, such as lasers, to realize the measurement of the surface topography with large discontinuity. In this paper, the white light source, with a single-chip CCD color camera, is used to accomplish multi-wavelength phase-shifting interferometry. In addition, we propose an algorithm which combines white light phase-shifting algorithm, equivalent wavelength method and fringe order method to achieve measuring and calibrating the micro-structures ranging from nanometer scale to micrometer scale. Finally, the proposed method is validated by a traceable step height standard.     

Array illuminator based on self-imaging in white light

An array illuminator is a device/optical system that splits an incoming beam of light into an array of many light spots/beams. It is useful in logic systems and in optical digital computing or in switching systems to energize arrays of components such as logic gates, optically bistable devices and electro-optic modulators. Array illuminators working in white light are interesting because they do not suffer from coherent noise and yield better signal-to-noise ratio. We propose configurations for array illuminator based on Fresnel diffraction and working under white light illumination conditions. Performance evaluation of the illuminators is also undertaken and the results of investigation are reported.     

Measurement of optical constants of thin polymer films using spectrally resolved white light interferometry

Using the spectrally resolved white light interferometry we present our experimental results on the measurement of the optical constants of thin polymer films coated on a transparent substrate. As an extension to our previous work (J. Opt. Soc. Am. B12, 1559 (1995)) on thick glass plates, we have shown here that this technique can be effectively applied to very thin polymer films also. We have improved the accuracy of our results by using the Sellmeier dispersion formula for fitting the data. From the width and position of the zero-order fringe and the frequency of modulations in the white light spectrum, the refractive indexn(λ) and thicknesst of the thin polymer films are calculated. To study the accuracies involved in the technique, PVA, PMMA and PS films of varied thicknesses are coated on glass plates and the measured values are compared with ellipsometer studies.     

White light interferometry test and analysis of LiNbO3 polarizer

White light interferometer can be used to measure the amplitude extinction ratio (ER) of polarizer and coupling distribution in fiber. A LiNbO₃ polarizer coupled with a polarization maintaining fiber and a silica planar waveguide at the two ends was measured using white light interferometer. According to the principles of optical coherence domain polarimeter (OCDP) technique, the test scheme is analyzed and presented to measure the ER of LiNbO₃ polarizer with its apparatus proposed correspondingly. By analyzing the interference intensity, both the ER of LiNbO₃ polarizer and its coupling crosstalk with optical fiber and waveguide are obtained. The results illustrate that the ER of a 5 mm-long LiNbO₃ polarizer is 71 dB and the crosstalk of the coupling points are around 40 dB. The results have good agreement with analysis.     

基于白光频域干涉的大台阶高度测量方法

基于白光频域干涉的基本原理,提出了一种可实现高分辨率和大台阶高度测量的方法,利用该方法进行台阶高度测量时,其测量范围取决于所用干涉光源的中心波长和光谱仪的分辨率,可达mm量级。在原理验证性实验中,利用该方法已经实现了最大高度为298.57 m的台阶高度测量,多次重复测量的标准偏差不超过0.03 m,最大均方根误差为0.94 m,实验测量结果与台阶高度真实值具有很好的一致性。     

Low-coherence interferometry based roughness measurement on turbine blade surfaces using wavelet analysis

In this paper, a non-contact optical system, a low-coherence interferometer (LCI), is introduced for the purpose of measuring the surface roughness of turbine blades. The designed system not only possesses a high vertical resolution and is able to acquire the roughness topography, but also it has a large vertical scanning range compared to other commonly used optical systems. The latter characteristic allows us to measure turbine blades surfaces with large curvature without collisions between the lens and the measurement object. After obtaining the surface topography, wavelet analysis is applied to decompose the original surface into multiple bandwidths to conduct a multiscale analysis. The results show that the developed LCI system proofs a good performance not only in obtaining the surface topography in the roughness scale but also in being able to measure surfaces of objects that possess a complex geometry in a large vertical range. Furthermore, the applied biorthogonal wavelet in this study has performed good amplitude and phase properties in extracting the roughness microstructures from the whole surface. Finally, the traditional roughness parameters, such as the mean surface roughness S_a and the Root Mean Square (RMS) roughness S_q, are evaluated in each decomposed subband and their correlations with the scale of each subband are analyzed.     

Talbot interferometry with an adaptive light intensity compensator

Talbot interferometry with a larger applicable scope has been investigated based on the intensity amplification method to weak moiré fringes by using photorefractive crystal as a light amplifier. It not only has function of conventional Talbot interferometry, but also is suitable for situations such as weak incident beam and detected object with strong absorption. The investigation indicates that the method or technique is feasible and the results of theoretical analysis are verified by experiments. Based on this investigation, Talbot interferometry with an adaptive light intensity compensator is proposed and some merits and demerits of the technique have briefly been discussed.     

Dispersive white-light spectral interferometry including the effect of thin-film for distance measurement

A spectral-domain white-light interferometric technique is used for measuring distances in a Michelson interferometer with a mirror represented by a thin-film structure (TFS) on a substrate. A fibre-optic spectrometer is employed for recording spectral interferograms that include wide wavelength range effects of dispersion in a cube beam splitter and multiple reflection within the TFS. Knowing the effective thickness of the beam splitter, its dispersion and parameters of the TFS and substrate, the positions of the second interferometer mirror are determined precisely by a least-squares fitting of the theoretical spectral interferograms to the recorded ones. We apply the technique to the beam splitter made of BK7 optical glass and to a uniform SiO₂ thin film on a silicon wafer. We compare the results of the processing that include and do not include the effect of the TFS.     

Control of the cool/warm white light generation from lanthanide ions in monoclinic double tungstate crystals

We studied the physical effects arising from the combination of several concentrations of luminescent ions, Ho, Tm and Yb in a biaxial crystal to achieve the optimum multicolour emission for cool or warm white light generation. White light is generated by the simultaneous emission and combination of three photons at wavelengths, 475 (blue), 542 (green) and 651 nm (red) with associated energies, 21,053 cm⁻¹, 18,450 cm⁻¹ and 15,361 cm⁻¹, respectively. The physical mechanism that generated the white light involved the absorption of infrared photons and after partial energy transfer to neighbouring ions, excited state absorption and upconversion phenomena took place to combine the emerging photons at the above wavelengths. White light is generated with rather high efficiency and very low excitation threshold. The control of simultaneous light generation is accomplished with the amount of dopant ions in the crystal.     

Investigation of light scattering from rough periodic surfaces — numerical solutions

The Beckmann scalar scattering model based on the Kirchhoff approximation was used to investigate the scattering of light from periodic surfaces whose roughness amplitude is comparable to, and greater than, the illumination wavelength. Solutions by numerical integration were obtained for surfaces of different profiles and of different roughnesses. It was found that the scattering patterns from these surfaces were very different at large roughness amplitudes. As the incident angle was varied on a given surface, it was also observed that the intensity of any individual diffraction order oscillated and the degree of oscillation was directly related to roughness. By utilizing this property, a new procedure could be developed for surface roughness assessment.     

一种基于PFO掺杂的理想白光有机电致发光器件

研究了以芴类蓝光材料PFO为主体,通过掺杂MEH-PPV得到单层的白光有机电致发光器件,并从掺杂浓度对器件的光谱特性和色坐标稳定性的影响方面对其发光性能进行了分析研究。在MEH-PPV以2.5Wt%掺杂时,器件开启电压为3V,发光色坐标可达到标准白光等能点(0.33,0.33),器件发光色坐标在5～20V很宽的范围内随电压变化幅度很小,基本稳定在白光区。     

The measurement of the diameter change of a piezoelectric transducer cylinder with the white-light interferometry

The measurement of the diameter change of a piezoelectric transducer (PZT) cylinder with the white-light interferometry is proposed and experimentally demonstrated. One arm of a Mach–Zehnder interferometer (MZI) is wrapped on the PZT cylinder, and the phase change of the interferogram of the MZI is used to determine the diameter change when a DC voltage is applied on the PZT cylinder. The Fourier transform white-light interferometry is used for recovering the phase change of the interferometer. The experimental results show that the diameter change resolution of 0.8 nm for the PZT cylinder with diameter of 40 mm is achieved.     

基于白光频域干涉的大台阶高度测量方法

基于白光频域干涉的基本原理,提出了一种可实现高分辨率和大台阶高度测量的方法,利用该方法进行台阶高度测量时,其测量范围取决于所用干涉光源的中心波长和光谱仪的分辨率,可达mm量级。在原理验证性实验中,利用该方法已经实现了最大高度为298.57μm的台阶高度测量,多次重复测量的标准偏差不超过0.03μm,最大均方根误差为0.94μm,实验测量结果与台阶高度真实值具有很好的一致性。     

声悬浮过程的激光全息干涉研究

利用二次曝光全息干涉术实现了对单轴式声悬浮声压场的研究.分别拍摄了悬浮不同物体和 不同输出功率情况下声悬浮场的多幅全息图，并进行了对比分析.结果表明，实验中获得的 声压分布图样与由声波动方程获得的理论声压分布基本一致，其相应中轴线的强度分布也具 有很好的一致性.与以往的声场测量方法相比，二次曝光法非接触、无干扰及全场测量的优 势在声悬浮场测量中得以充分体现，该方法的引入不但简化了声悬浮场测量的实际操作，而 且可以更直观地获得全场信息，为优化声悬浮系统提供了实验依据. 关键词： 全息干涉术 二次曝光法 声悬浮 谐振     

Review of surface profile measurement techniques based on optical interferometry

With the fast development of modern science and technology, two or three-dimensional surface profile measurement techniques with high resolution and large dynamic range are urgently required. Among them, the techniques based on optical interferometry have been widely used for their good properties of non-contact, high resolution, large dynamic measurement range and well-defined traceability route to the definition of meter. A review focused on surface profile measurement techniques of optical interferometry is introduced in this paper with a detailed classification sorted by operating principles. Examples in each category are discussed and analyzed for better understanding.     

Multiple atomic wave interferometry with standing-waves of light

Fringe shapes in a multiple-beam de Broglie-wave interferometer based on the atomic Kapitza-Dirac effect are studied. An all-optical implementation of such a device is proposed. A realization in the time-domain, using Bose-Einstein condensates released from a trap, seems viable within the present state of the art. Received 5 April 2000 and Received in final form 14 July 2000     

基于莫尔理论的双波长全息干涉术分析

当用双波长全息干涉术通过单次曝光法或双曝光法对物体进行测量时 ,其效果相当于用一个等效波长λeq=λ1 λ2 /|λ1 -λ2 |对物体进行测量 ,扩大了测量波长的可选范围。采用莫尔理论从一个全新的角度对双波长全息干涉术的基本原理进行了分析和探讨 ,不仅揭示出了二者之间存在着的必然内在联系 ,而且还进一步证明了双波长全息干涉术的准确性和可行性 ,从而扩展了双波长全息干涉术的应用领域     

A new concept of white light generation using a nano-waveguide for the solar radiation collection use

We propose a novel system of a nano-waveguide that can be used to generate the continuous optical spectrum, i.e. white light. A system consists of two micro-ring resonators and a nano-ring resonator that can be integrated into a single system. The large bandwidth signal is generated using a soliton pulse propagating within a Kerr-type nonlinear medium, whereas the continuous bandwidth or wavelength of light signal can be performed. Results obtained have shown the potential of using such a system for white light source generation and amplification, which is discussed. The amplified pulse can be stored within a nano-waveguide, which is allowed to form the continuous spectrum after amplification. Alternatively, the low-level solar radiation can be amplified, and the bandwidth signals can also be enlarged.