Quadrature phase-shifting interferometer with a polarization imaging camera

We present a new high-speed phase distribution measurement, in which a polarization imaging camera is applied to a quadrature phase-shifting interferometer. The polarization imaging camera composed of a polarizer-mask on a detector array can provide simultaneously two phase-shifted data in quadrature. Two sets of two phase-shifted data in quadrature are obtained before and after a change of the interferometer such as object displacement or environmental disturbances. Phase sum and difference distributions of the interferograms between two states with arbitrary phase-shift in the interferometer are calculated with the two sets of two phase-shifted data in quadrature. This phase calculation method in the pixel displaced phase-shift method has such advantage that phase-shifted data required for the calculation of phase distributions can be obtained by only two pixels in the polarizer-mask detector array, which means no reduction of the image resolution in the other direction. The principle of this technique and experimental results are presented.     

A single-shot pixellated phase-shifting interferometer utilizing a liquid-crystal spatial light modulator

We introduce a novel phase-shifting pixellated interferometer based on a liquid-crystal spatial light modulator and simulate the expected performance. The phase-shifted frames are captured simultaneously, which reduces problems arising from vibrations and air turbulence. The liquid-crystal spatial light modulator is flexible and can be configured to provide a large number of phase-shift levels and geometries to reduce measurement error.     

Digital phase-shifting interferometer with an electrically addressed liquid-crystal spatial light modulator

A digital phase-shifting interferometer with a liquid-crystal-display coupled, parallel aligned, nematic liquid-crystal spatial light modulator is developed. The optical phase shift in the Michelson-type polarization interferometer is achieved by a digital phase shift of a grating displayed on the spatial light modulator. Accurate experimental results of using the heterodyne system for pi/2 phase steps were demonstrated. A phase-shifting interferometer with no moving parts and no requirement for calibration of the value of the phase shift was achieved.     

Simple phase-shifting lateral shearing interferometer

A phase-shifting electronic speckle pattern shearing interferometer with a very simple shearing device is proposed. Two partially reflective glass plates are used to introduce the shear in this new interferometer. The reflection coefficients of the coatings on the two plates are 0.3 and 0.7. The distance between the two glass plates controls the size of the shear. The proposed new interferometric system is simple, flexible, and low cost.     

Polarization phase-shifting Jamin shearing interferometer

The Jamin shearing interferometer is very useful in wavefront testing, especially for the low coherent light. Based on this interferometer, a polarization phase-shifting Jamin shearing interferometer is proposed to improve the performance. In the interferometer, two interference beams are linearly polarized and a polarization phase shifter is applied to realize the phase shifting. Different types of configurations of the interferometer are given. With phase-shifting interferograms, the precision of the interferometer can be improved. The interferometer is kept as an equal optical path system and its shearing amount remains changeable with simple structure and easy operation. In experiments, phase-shifting interferograms are obtained by rotating the analyzer. The usefulness of the interferometer is verified.     

Common-path phase-shifting interferometer with binary grating

An experimental setup for phase extraction of 2D phase distributions is presented. The system uses a common-path interferometer consisting of two windows in the input plane and a translating grating as spatial filter. In the output, interference of the fields associated with replicated images of the input windows is achieved by a proper choice of the windows spacing with respect to the grating period, the focal length of the transforming lens and the wavelength of the coherent illumination employed. Because in this type of grating interferometer a grating is placed as a spatial filter, the phase changes which are needed for phase-shifting interferometry can be easily performed with translations of the grating driven by a linear actuator. Some experimental results are shown.     

移相干涉仪的抗振技术研究进展

在对光学元件面形进行检测和光学系统成像质量的评价中,移相干涉测量技术有着广泛地应用。但是,光学干涉仪的测量精度对环境的要求非常苛刻,环境的振动和空气的扰动会对测量结果产生很大影响。提高移相干涉仪的抗振性很有必要,受到广泛重视。国际上移相干涉仪的抗振技术主要包括主动抗振和被动抗振两方面,两种技术具有各自特点。     

A Michelson twin interferometer for phase-shifting measurement

Optical Review - Phase-shifting measurement with a Michelson twin interferometer, in which two interference signals concerning measurement and reference beams are generated from a common optical...     

Multipass interferometer using a filamentary spatial filter

A multiple pass interferometer using a filamentary spatial filter is developed. We can change the sensitivity of the interference fringe pattern by selecting the order of multiply reflected image without reduction of the fringe visibility.     

空域移相偏振点衍射波前检测技术

点衍射干涉仪结构简单、共光路、测量精度高, 空域移相干涉仪抗振性能优越, 两者在波前检测领域获得了广泛的应用. 本文采用激光打孔技术, 通过在金属纳米线栅偏振片上制备小孔, 制作了偏振点衍射板; 结合分光结构的空域移相技术, 搭建了空域移相偏振点衍射干涉仪, 并对一焦距为550 mm, F_#10的平行光管准直物镜透射波前进行测量, 与法国Phasics公司生产的商业化波前传感器SID4的测量结果相比较, 两者峰谷值相差0.09λ, 均方根值相差0.012λ ; 利用35项Zernike多项式拟合两者的测量结果, 将拟合得到的系数在同一坐标轴下绘制成两条曲线, 两者基本重合, 从而验证了所搭建的空域移相偏振点衍射波前检测装置的测试精度. 从而在传统点衍射干涉仪的基础上引入了空域移相技术, 实现了波前的高分辨率、高精度、实时检测, 并且提高了对振动、气流等环境因素的抗干扰能力.     

Enhanced phase-shifting measurement with a double-passed Michelson interferometer

Optical Review - A double-passed Michelson interferometer for enhanced phase-shifting measurement is described in this paper. Two interference signals concerning measurement and reference beams are...     

Fizeau型偏振移相干涉仪的实验研究

研究了一种Fizeau型偏振移相干涉仪。以中心波长为650nm的多纵模半导体激光器作为光源,利用光源的短相干特性和一套偏振延迟装置分出一对偏振方向正交的参考光和测试光,采用巴比涅-索列尔补偿器作为偏振移相器。测试了一块平行平板的前表面面形,面形PV值为0.0682λ,RMS值为0.0127λ。该方法的优点是移相精度高,移相时无须推动参考镜,适用于大口径光学系统的干涉测试,可消除多表面干涉杂散条纹的影响。     

Improved phase-shifting diffraction interferometer for microsphere topography measurements

In this study, an improved phase-shifting diffraction interferometer for measuring the surface topography of a microsphere is developed. A common diode-pumped solid state laser is used as the light source to facilitate apparatus realization, and a new polarized optical arrangement is designed to filter the bias light for phase-shifting control. A pinhole diffraction self-calibration method is proposed to eliminate systematic errors introduced by optical elements. The system has an adjustable signal contrast and is suitable for testing the surface with low reflectivity. Finally, a spherical ruby probe of a coordinate measuring machine is used as an example tested by the new phase-shifting diffraction interferometer system and the WYKO scanning white light interferometer for experimental comparison. The measured region presents consistent overall topography features, and the resulting peak-to-valley value of 84.43 nm and RMS value of 18.41 nm are achieved. The average roughness coincides with the manufacturer's specification value.     

Using a programmable interferometer for digital phase-shifting speckle interferometry

The use of a programmable phase-shifting interferometer to detect the deformation of scattering surfaces is described. The interferometer is a commercial instrument in use for optical testing applications; the sample surface is imaged as a speckle pattern. The measuring procedure and the program are outlined, and an experimental demonstration on an aluminium plate under load is given.     

Polarization phase-shifting Newton interferometer for plane optical surface measurements

This Letter introduces a polarization phase-shifting Newton interferometer that can be utilized for plane optical surface measurements, a setup constructed to realize the interferometer, and the experimental results from the use of the setup. The results confirm not only the validity but also the feasibility of the interferometer.     

移相式干涉仪在锥体棱镜角度测试中的应用

为了实时、高精度地测试光学零件，对移相式数字波面干涉仪在锥体棱镜角度测试中的应用进行了研究。通过锥体棱镜二面角偏差计算方法得到了二面角偏差和干涉波面之间的关系，分析了干涉波面的形状与锥体棱镜综合误差的关系，编写了锥体棱镜角度和综合误差测试程序，并且在移相式数字波面干涉仪和ZYGO干涉仪上分别对锥体棱镜进行测试，给出了2者的比较测试结果。结果表明，移相式数字波面干涉仪测量锥体棱镜二面角偏差的误差在0.3″范围内，RMS值的测量误差在λ/50内；提出的方法可实现检测过程的自动化。     

Removal of carrier frequency in phase-shifting techniques

The existence of carrier frequency is unavoidable in many phase-shifting techniques. It makes the phase-unwrapping procedure more difficult, especially when speckle-like noise exists in the wrapped phase map. In this paper, it is shown that the carrier frequency is approximately equal to the average of the first difference of the phase. To remove the carrier frequency, we compute the first difference of the phase before attaining the phase map, subtract the average of the first difference, and integrate to get the phase map without carrier frequency. Computer simulation and experimental results show this method as being profitable for phase unwrapping.     

Measuring spatial coherence by using a reversed-wavefront Young interferometer

A very simple optical setup for the measurement of the modulus and the phase of the two-point correlation function of a partially coherent light field is presented. The system consists of a slightly modified version of a Young interferometer and requires a single Young mask in order to determine the correlation function at any pairs of points. Experimental results are presented for the case of a synthesized partially coherent secondary source.     

Wavelength modulation in a two-window common path interferometer for phase-shifting

A novel and simple method for phase-shifting under the scheme of a two-window 4f common path interferometer configuration with a binary grating at the Fourier plane is proposed. The proposal is based on periodicity variations of the grating grooves in the frequency space, which is emulated in an experimental implementation by changing the wavelength of a tunable laser diode used as the light source. Because of the common path configuration, it is expected to diminish errors due to undesired vibrations and optical aberrations. The viability of the proposal will be sustained with simulated and experimental, which include phase-shifted interferograms and reconstructed wavefronts. Due to the characteristics of the proposed experimental setup, it can be easily replicated and automated.