Phaseshifting interferometry with genetic algorithm. The new interferometer operates based on a principle similar to that of the phaseshifting method. Measurements using fourier transform phase shifting. Interferometry is no exception, and the prime manifestation of this situation has been the development of phase shifting interferometry psi. Phaseshifting interferometry is a coherent optical method that combines high accuracy with high measurement speeds. Sar processing, sar interferometry, software, phase unwrapping, height mapping introduction. Comparing how the two software programs analyze the interferograms would also be extremely interesting.
Comparison of bath and zygo interferometer testing the. Many of the recent advances in understanding of phase shifting algorithms have yet to be incorporated into the software for commercial phase shifting interferom a toolbox for designing and analyzing phase shifting interferometry algorithms with characteristic polynomials nist. Multiwavelength phaseshifting interferometry for micro. Using a programmable interferometer for digital phaseshifting speckle interferometry. Phase shifting interferometry with genetic algorithmbased twin image noise elimination joonku hahn, hwi kim, seongwoo cho, and byoungho lee school of electrical engineering, seoul national university, gwanakgu sillimdong, seoul 151744, korea. Coretm 2 duo and the 3 gb memory, and with the software package of matlab. Phaseshifting interferometry avoids the need to track the location of the. Measuring the phase transfer function of a phaseshifting. Subnanometer height sensitivity by phase shifting interference. A toolbox for designing and analyzing phaseshifting. Pdf phase shifting interferometry is a wellestablished technique for areal surface characterisation that. Qpsi vibration tolerant interferometry eliminates ripple in phase data caused by small vibrations in a cavity, while maintaining a highprecision onaxis measurement configuration. This paper discusses four areas in which computerized interferometric measurement improvements have been made in the measurement of surface shape and surface roughness. The preceding example is a onedimensional application of the phase.
Phase shifting interferometry is a wellestablished technique for areal surface characterisation that relies on digitisation of interference data acquired during a controlled phase shift, most often introduced by controlled mechanical oscillation of an interference objective. The extended source, the star, can be decomposed in an incoherent sumof infinitesimal source points, the brightness can so be written like. Ted clancy germano iannacchione george heineman group 108 staff. Using a programmable interferometer for digital phase. Phaseshifting interferometry is a powerful means of analyzing interferograms to recover the. An advanced phase retrieval algorithm in nstep phase. Phaseshifting interferometry with genetic algorithm based. We use phase shifting interferometer to generate fringes, and the phase. A complete software package of the algorithm in matlab is.
Optical phase shift measurements in interferometry 2. Traditionally, interferograms were measured by locating the center of a fringe and then tracing along the fringe. Phase interferometry direction finding wpi advisors. Associations of durango interferometry software with the. An advanced phase retrieval algorithm in nstep phase shifting interferometry with unknown phase shifts. Phaseshifting interferometry university of arizona. However, for the very large primaries needed for the next generation of telescopes, it is difficult and expensive to keep vibrations low enough for this method to work. Phaseshifting analysis in moire interferometry and its. In this case, phase shift methods can be applied to determine the opl and the fringe visibility. A new method for threedimensional image formation is proposed in which the distribution of complex amplitude at a plane is measured by phase shifting interferometry and then fresnel transformed by a digital computer. Phase retrieval in twoshot phaseshifting interferometry based on. Popular interferometric measurement techniques include phase shifting interferometry psi, and vertical scanning interferometry vsi, also known as scanning white light interferometry swli or by the iso term coherence scanning interferometry csi, csi exploits coherence to extend the range of capabilities for interference microscopy.
Types of phase shifting pdi systems phase shifting pdi with single pinhole. In interferometry, interference phases are calculated from fringes, including reading fringes, filtering, phase calculating and zernike fitting. Chapter 14 phase shifting interferometry engineering360. The method can reconstruct an arbitrary cross section of a threedimensional object with higher image quality and a wider viewing angle than from conventional digital holography. There are many ways to introduce a phase modulation or shift. The concept behind phaseshifting interferometry is to apply a timevarying phase shift between the reference and test wavefronts. The phase shifting is obtained by introducing a transmissive grating to the substrate of a pointdiffraction interferometer pdi,910 as illustrated in fig. Phasecam compact inteferometer 4d technology corporation.
Phaseshifting technique for improving the imaging capacity. The image processing of the phase maps is performed by unwrapping algorithms, which consider discontinuities as unsteady deformations, noise and inexactly modulated areas. New selfcalibrating phase stepping method is developed and reported. Phaseshifting interferometry for determining optical surface. Phaseshifting interferometry based on principal component. A zygo fourier transform phase shifting interferometry ftpsi system was used by rob brown. Direct phase measurement interferometry and optical testing. Phase shifting interferometry information on ieees technology navigator. Second, measurements can be taken at every element in the photodetector array directly yielding optical pathlength differences on a regularly spaced grid. Us patent application for phase shifting interferometry with. So, i would like to see both a bath and a good, calibrated, professional interferometer test the same two or three optics, ideally starting with good spheres at say f2. Conventional phase shifting interferometry psi needs at least three interferograms.
Deck zygo corporation, laurel brook road, middlefield, ct. The accuracy of optical phase shifters is limited by the inherent characteristics of the piezoactuators or pzt such as nonlinearities, hysteresis, creep and thermal drift. Conventional multiwavelength phase shifting interferometry utilizes two or three monochromatic light sources, such as lasers, to realize the measurement of the surface topography with large discontinuity. Phase difference is the difference, expressed in degrees or time, between two waves having the same frequency and referenced to the same point in time. Phase sensor is the basis for interferometry measurements at trioptics. System for phase shifting interferometry in the presence. Interferometric surface topography based on twodimensional fourier transform 2d fft is compared to phase stepping technique.
Phase shifting interferometry psi is a wellestablished opticalcharacterization technique 1. Phase comparison monopulse also called phase interferometry describes a technique that can be used in radar and direction finding applications to accurately estimate the direction of arrival of a signal from the phase difference of the signal measured on two or more separated antennas. In this paper, we describe the principle of a multiaperture interferometer that uses a phaseshifting technique and is suitable for quick, snapshot imaging of astrophysical objects at extreme angular resolution through fourier inversion. Typically, a conventional phase shifting interferometer is constructed with both reference and test optical paths arranged in what is known as a twymangreen configuration, as shown in figure 1. In this paper, the white light source, with a singlechip ccd color camera, is used to accomplish multiwavelength phase shifting.
Phaseshifting interferometry for determining optical. This very sophisticated interferometry software program by diffraction international permits the interferometer to make precision measurements of the surface and provides a number of revealing graphics of the surface. Phase shifting interferometry is a wellestablished technique for areal surface characterisation that relies on digitisation of interference data acquired during a controlled phase shift, most. Associations of durango interferometry software thanks to, you will find out what program you should use to open the files with unknown extensions. Zygos proprietary qpsi data acquisition is enabled by a zygomanufactured highpower hene laser source and patented software algorithms no other vibration tolerant acquisition technique compares. A windowbased graphics interface for phase shifting in a moire interferometry system is introduced. Costeffective upgrade kits to refurbish and enhance older temporal phase shifting laser interferometer systems. Surface measurement 101 noncontact 3d optical metrology. Random phaseshifting interferometry based on independent. In this study, an innovative phaseshifting technique is proposed, coupled with imageprocessing software, to investigate several interesting problems in electronic packaging.
The interferometric movie is further drag and drop into imagej software to. Part 9 phase shifting interferometry classical analysis of. A toolbox, for the opensource computer algebra system maxima, simplifies. The graham model 2vp phase mite is an example of a phase shifting interferometer. The optical phase shifter system the optical phase shift in the reference beam is determined by the phase delay between the two radio frequency rf driving signals applied to the acoustooptic modulators once properly aligned. A general method of surface profiling with phase shifting interferometry techniques uses iterative linear regression to fit the sequence of interferograms to a physical model of the cavity. Bioucasdias2 1department of signal processing, technology university of tampere. Bath interferometer page 8 atm, optics and diy forum. This mode is ideal for smooth parts with low departure pv phase stepping technique.
By performing the recombination of pixel position, a sequence of phase shifting interferograms with random phase shifts are decomposed into a group of mutual independent components, and then the background and the measured phase of interferogram can obtained. The phasecam 6000 incorporates dynamic interferometry technology, using a single camera, highspeed optical phase sensor to make wavefront measurements in less than 30 microseconds over 5000 times faster than a temporal phase shifting interferometer. We describe a test mirror with a special height relief that can be used to measure the height transfer function for the interferometer in a fashion analogous to the measurement of the. Phase shifting interferometry related conferences, publications, and organizations. Optsuite has support for firewire cameras, gpibdevices, linear stages and comes with an analysis package. This method for obtaining phase information from interferograms is now known as phaseshifting interferome try psi. In addition, you will find here information about file conversion. Wavefront reconstruction in phaseshifting interferometry. The sensor is modular and can be configured with various measurement diameters and stands for specific measurement tasks. This method for obtaining phase information from interferograms is now known as phase shifting interferome try psi. Measure mode and z resolution optical profilometer training. A toolbox, for the opensource computer algebra system maxima, simplifies analysis and design of arbitrary phaseshifting algorithms and can help incorporate them in commercial. Phaseshifting interferometry overcomes these limitations. Portable connector end face geometry interferometer.
Optsuite is a java interferometer software build on top of the eclipse rcp mainly used for phaseshifting interferometry. Smart psi smart psi combines a csi scan to focus the instrument and determine the coherence profile of the surface with a series of rapid psi phase shifting interferometry measurements to determine the highresolution phase profile of the surface. In phaseshifting interferometry with unknown phase shifts. First, phaseshifting interferometry does not rely on. Qpsi vibration tolerant interferometry qpsi technology eliminates ripple and phase noise caused by common sources of vibration such as grinding and polishing equipment, motors, pumps, blowers, and personnel, which means you can use the verifire hd system right on the production floor, without the hassle and expense of vibration isolation tables. Both took many interferograms at different mirror orientations and the results were averaged by their software. Interferometer fringe pattern processing software for. In characterizing the performance of a phaseshifting interferometer, the dependence of the measured height on the spatial frequency is rarely considered.
Phaseshifting interferometry for determining optical surface quality. Interferometric measurements of transparent spheres, however, are difficult due to the interference of light reflected by the back surface of the sphere. Unlike many of the techniques discussed elsewhere in this book, psi is not a specific optical hardware configuration, but rather. Interferometry phasemeasurement interferometry 365. This can be achieved, for example, by mounting the reference optic on a linear transducer, such as a piezoelectric crystal. A similar fourier method1 is used to find the resul. Surface measurement 101 noncontact 3d optical metrology dr. The reference phases are obtained from the additional straight fringes on the interfering plane by the fastfouriertransform method. Phase shifting interferometry addresses several issues associated with the classical analysis of static interferograms. Phase shifting interferometry based on principal component analysis j. An industryleading application for acquisition and data analysis of metrology results. The efficiency of the telescope is a function of the sky position and we will use as,s 0. Measurements using fourier transform phase shifting interferometry leslie l.
Notes on the application of electronic speckle pattern. A few advantages of the proposed design are highlighted, among which are radiometric efficiency, field of. Wavefront reconstruction in phase shifting interferometry via sparse coding of amplitude and absolute phase v. Wavefront reconstruction in phaseshifting interferometry via. Phase shifting interferometry is a wellestablished technique for areal. Jun, 2010 many of the recent advances in understanding of phaseshifting algorithms have yet to be incorporated into the software for commercial phase shifting interferometers. We describe a generalized phaseshifting interferometry for which the reference phases are directly evaluated at each time that the interference fringe data are read. These include a diffraction grating interferometer by kwon and the phase shifting point diffraction interferometer. This interferometry provides all the information needed to measure the connector without the need for costly phase shifting devices.
Fast, memsbased, phaseshifting interferometer1 hyuck choo2, rishi kant3, david garmire2, james demmel2, and richard s. By applying phase shifting techniques to the recorded speckle patterns, results of high accuracy can be achieved. One of the methods is phase shifting interferometry. Phase fizeautwymangreen interferometer from trioptics.
Phaseshifting interferometry based on principal component analysis j. Fourier transform phase shifting interferometry using wavelength tuning can, in principle, separate the fringe patterns originating from the multiple cavities. Mar 01, 2007 phaseshifting interferometry based on such wavelength tuning is described in, for example, u. A few advantages of the proposed design are highlighted, among which are radiometric efficiency, field of view equivalent to those of fizeau interferometers, and a preliminary calibration. This algorithm is then applied to an information security system based on double random phase encoding in the fresnel domain.
Lets describe the source intensity spatial distribution with the function fs in units of power incident per area per solide angle on the sky. With an easytoposition, fibercoupled measurement head and motorized controls, the phasecam 6000 is ideal for measuring large, focal optical systems such as concave telescope mirrors and lens systems, as well as smallaperture, afocal components such as. Psi has existed in its basic form for less than 3 decades, and may be regarded as temporal. The modular sar processor msp is a system for deriving synthetic aperture radar images from raw sar data from both airborne and spaceborne sensors. The concept of psi has been used for a long time in electrical engineering for determining the phase difference. Classically, one measures the positions of the fringe centers. There are many ways of transforming the conventional stationary interferometers into realtime dynamic interferometers. Quantifying the performance impact of one feature such as dynamic branch prediction can be dif. Intelliwavetm is a powerful interferometric acquisition and analysis program that is used to measure the.
Idea interferometric data evaluation algorithms software for fringe analysis and phase data reduction for one and a half decade software for interferometric fringe evaluation has been developed and used at technical university graz throughout a number of diploma and phdthesis. Phase shifting see interferometry versions have been created to increase measurement resolution and efficiency. Phase shifting interferometry psi used for testing smooth objects with very high precision vertical resolution 0. Shape software, extensive measurement analyses can be performed. Phase shifting interferometry overcomes these limitations. First, phase shifting interferometry does not rely on. An advanced phase retrieval algorithm in nstep phaseshifting. Phase shifting interferometry is a wellestablished technique for areal surface characterisation. The precision and accuracy of optical phase shifting technique is critical and affects the accuracy of optical measurements undertaken using phase shifting interferometers. A novel algorithm of twostep psi, with an arbitrary known phase step, by which a complex object field can be reconstructed with only two interferograms is proposed. Phase shifting interferometry avoids the need to track. Phase shifting interferometric psi techniques are among the most sensitive phase. These include moving a mirror or the figure 4 interference fringes for coherent and incoherent sources as observed at point x. Jul 01, 2016 in random phase shifting interferometry, a novel phase retrieval algorithm is proposed based on the independent component analysis ica.
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