These are added to the stock interferometer to enable the phase shifting to occur. This thesis proposes phase modulating interferometry as an alternative to phase stepping and phase shifting interferometry for use in the shape and displacement characterization of microelectromechanical systems mems creath, 1988. One of the methods is phase shifting interferometry. Us patent application for phase shifting interferometry with. Phase shifting interferometry avoids the need to track. Phaseshifting interferometry for determining optical surface. Second, measurements can be taken at every element in the photodetector array. Interferometry is no exception, and the prime manifestation of this situation has been the development of phase shifting interferometry psi. Measurements using fourier transform phase shifting interferometry leslie l. Us6924898b2 phaseshifting interferometry method and system.
Other optical imaging systems, for example, phase contrast microscopy, rely on a static ops. In this study, an innovative phaseshifting technique is proposed, coupled with imageprocessing software, to investigate several interesting problems in electronic packaging. Psa toolbox, twodimensional phase unwrapping, functions for phase shift diagnostics phase histograms, gutmannweber diagrams, and several functions for interfacing with camera. At left the phaseshifting hardware, new highresolution digital camera, and various connecting cables are shown. Optical phase shift measurements in interferometry 2.
The interferometer uses polarization to separate the test and reference beams, interfering what begin as orthogonal polarization states. Phase shifting algorithms in dspi are useful for extracting quantitative deformation data from the system. 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 flat mirrors and collimators. Second, measurements can be taken at every element in the photodetector array directly yielding optical pathlength differences on a regularly spaced grid. In phase shifting interferometry psi, an ops with a wide aperture and a linear medium is required 6.
In the shop jan 25, 2015 phase shifting interferometry. Depending on the measurement conditions and requirements two types of intomatik software are available. Measurements using fourier transform phase shifting. A comparative study of phaseshifting algorithms in digital. First, phaseshifting interferometry does not rely on. Ted clancy germano iannacchione george heineman group 108 staff. Deck zygo corporation, laurel brook road, middlefield, ct. Subnanometer height sensitivity by phase shifting interference. A modified carre algorithm for phase shifting interferometry.
The durango software takes care of doing all of the work, once properly set up. May 01, 2010 scanning interferometry is more suited to the measurement of mems devices because it had a much greater z range than phase shifting and modern algorithms such as those used in coherence correlation interferometry are able to match the precision of phase shifting over the much longer range. Phase shifting interferometry how is phase shifting. Phaseshifting interferometry for determining optical surface quality determining the surface quality of a critical component, the deviation from the intended shape whether. Due to the phase shifting algorithm the intomatikn offers higher accuracy and a larger measuring range. The concept of psi has been used for a long time in electrical engineering for determining the phase difference.
Phaseshifting interferometry for determining optical surface quality. Us20030160968a1 phaseshifting interferometry method and. Phaseshifting interferometry method and system zygo. Interferometry and its applications in surface metrology. Interferometric measurements of transparent spheres, however, are difficult due to the interference of light reflected by the back surface of the sphere. Reprintintech20172chapter 5 interferometry and its applications in surface metrology. An advanced phase retrieval algorithm in nstep phase. May 18, 2011 eliminating phaseshift errors in interferometry. The technique provides full 3d images with typical height. Liu, twoframe phaseshifting interferometry for testing optical.
The interferometric movie is further drag and drop into imagej software to. Coherence scanning interferometry csi refers to a class of optical surface measurement methods wherein the localization of interference fringes during a scan of optical path length provides a means to determine surface characteristics such as topography, transparent film structure, and optical properties. Malacara, optical shop testing john wiley and sons, 2007. Phaseshifting analysis in moire interferometry and its. Interferometry phasemeasurement interferometry 365. Phase retrieval in twoshot phaseshifting interferometry based on. Currently contains functions for phase calculations from phase shifted intensity data using arbitrary phase measuring algorithms see. By using our website you agree to the storage of cookies on your device. The storage pixels are read out to produce the video signal. Phase shifting interferometry, in optical shop testing, d.
Digital evaluation of interferograms sciencedirect. 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. Phasecam compact inteferometer 4d technology corporation. 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. Bioucasdias2 1department of signal processing, technology university of tampere. Phase shifting interferometry is a wellestablished technique for areal. A windowbased graphics interface for phase shifting in a moire interferometry system is introduced. Phase shifting interferometry psi is a wellestablished opticalcharacterization technique 1. Fourier transform phase shifting interferometry using wavelength tuning can, in principle, separate the fringe patterns originating from the multiple cavities. Mar 14, 2017 in phase shifting interferometry with unknown phase shifts, a normalization and orthogonalization phase shifting algorithm nopsa is proposed to achieve phase retrieval. Pdf interferometry and its applications in surface metrology. 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. This method for obtaining phase information from interferograms is now known as phase shifting interferome try psi.
Derivation of algorithms for phaseshifting interferometry. Laser interferometry an overview sciencedirect topics. 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 implement phaseshifting interferometry to extract amplitude and phase information from an interferometric near. Chapter 14 phase shifting interferometry engineering360. Our method uses a fast phase servo loop where the phase sample frequency is several kilohertz. Surface measurement 101 noncontact 3d optical metrology dr. The principle of holography is based on the fact that, via simultaneously recording a reference light laser beam split by a beam splitter and a returned, scattered light beam from the surface of a target on a holographic plate, reconstruction of an exact. Digital speckle pattern interferometry dspi is a tool for making qualitative as well as quantitative measurements of deformation of objects. Phaseshifting interferometry for determining optical.
Wavefront reconstruction in phaseshifting interferometry via. Pdf phase shifting interferometry is a wellestablished technique for areal surface. There are many ways of transforming the conventional stationary interferometers into realtime dynamic interferometers. Laser holographic interferometry is a technique combining laser interferometry and holography. In this case, phase shift methods can be applied to determine the opl and the fringe visibility. We describe a generalized phase shifting interferometry for which the reference phases are directly evaluated at each time that the interference fringe data are read. Wavefront reconstruction in phase shifting interferometry via sparse coding of amplitude and absolute phase v. Traditionally, interferograms were measured by locating the center of a fringe and then tracing along the fringe. 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.
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. 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. Unlike many of the techniques discussed elsewhere in this book, psi is not a specific optical hardware configuration, but rather. Eliminating phaseshift errors in interferometry springerlink. Phase shifting interferometry psi used for testing smooth objects with very high precision vertical resolution 0. Ishiiphaseextraction analysis of laserdiode phase shifting interferometry that is insensitive to changes in. A new instrument, the polarization phaseshifting pointdiffraction interferometer, has been developed by use of a birefringent pinhole plate. Phase shifting interferometric psi techniques are among the most sensitive phase. Mar 01, 2007 phaseshifting interferometry based on such wavelength tuning is described in, for example, u.
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