Holographic application laboratory holography and electronic speckle pattern interferometry espi are interferometric techniques. Digital holographic interferometry is normally referred to the superposition of an existing hologram reconstructed onto a real object to observe the differences between the first exposure. Holography follows a different principle from conventional photography. A p p l i e d o p tic s g r o u p d e p a r t ment o f p h y s i c s holographic interferometry 2 autumn term. For this case, a comparison with digital and image holographic interferometry using transmission and reflection holograms is. Digital recording and numerical reconstruction of holograms. Maged marghany, in synthetic aperture radar imaging mechanism for oil spills, 2020. In addition, there was an approximate twofold difference between the freshfixed and freshmacerated states. The success of doubleexposure holography as an interferometric technique for experimental stress analysis has lead to several recent publications dealing with the theoretical expression which describes the resulting photoelastic patterns. Interferometry and holographic interferometry are becoming useful tools for precision measurements.
Apr 08, 2020 the holograms obtained in the present study revealed that there was a difference in the stress transmission among fresh, fixed and macerated mandibles. This technique is particularly useful in a diverse range of applications and markets, from interferometric microscopy to data storage processing, from anticounterfeit measures for currency, credit cards, and personal identification documents to projection displays for the arts and. Holographic interferometry an overview sciencedirect. Holography is a threedimensional imaging technique produced and reconstructed using a laser light source. Rastogi, pierre jacquot, leopold pflug optical engineering 1988. Naturally, a hologram is a precise tapping of an electromagnetic field, more willingly than a snapshot formed with the aid of a lens. Imageplane holographic interferometry by the lens method has several advantages over offaxis holography. Go outside if applicable and let sunlight reflect off the hologram. Digital holographic interferometry dhi and electr onic speckle pattern interferometry espi in the longwave infrared lwir spectral range have been used recently for different applications, through the combination of co2 lasers with thermal imaging devices for recording numerically digital holograms or specklegrams 1,2.
Three types of holographic interferometry, being 1. On the other hand i,t is difficult to register optical path changes larger tha 10n 0 a fo onr e object. This paper describes the extension of current theory to include the effect of an intensity difference between the light used during the first exposure and. Subsequent exposures on the same photographic plate are made while the object is subjected to some stress.
The difference between all this systems is subtle, in general we speak about speckle interferometry when a medium. Illustrations of digital holographic interferometry. Advancements in holographic photoelasticity springerlink. Further applications are imaging and microscopy, where it is advantageous to refocusthe area under investigation by numerical methods. The techniques of data acquisition and evaluation are discussed. Phaseshifting interferometry by amplitude modulation. Interferometry is a technique in which waves, usually electromagnetic waves, are superimposed, causing the phenomenon of interference, which is used to extract information. At first holography and holographic interferometry were thought to. Electronic holography and shearography in experimental. Pdf measurements of concentration differences between.
When interference fringes are very closely spaced, the phase data contain high frequencies where 2p ambiguities cannot be resolved. Fundamentals of holography and interferometry springerlink. Digital holographic interferometry in the longwave. In 1978 abramson demonstrated a method called then the same speckle pattern is present in both lightinflight holography to display the locus of the images in regions in which the phase difference is 2tr zero opticalpath difference opd between the object or congruent values. Holography a what are the major differences between analog classical, nondigital holography and photography. Osa digital holographic interferometry with co2 lasers and. Today digital holographic interferometry dhi is considered a modern fullfield nondestructive technique that allows generating 3d quantitative data of a wide variety of specimens. Pdf holographic images of test targets were reconstructed from a new, selfprocessing photopolymer material. Holographic interferometry hi is a technique which enables static and dynamic displacements of objects with optically rough surfaces to be measured to optical interferometric precision i.
For the fringe analysis in interferometry for testing optical components the different methods can. Holography allows for the use of various interferometric methods for measuring processes of heat and mass transfer. Each section of a hologram, contains a complete image of the original object, viewed from a vantage point that corresponds to the sections position on the hologram. These works are the basis of optical tomography and provide us with the link between holographic data and 3d form. Holographic image of a fixed right dog hemimandible. Interferometry is an important investigative technique in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy and its applications to chemistry, quantum. Digital holographic interferometry in the longwave infrared. Digital holographic interferometry for analyzing high density. The effectiveness of the proposed technique is demonstrated by experiments on. Comparative holographic moire interferometry for nondestructive. Robinson and william 1986 and also to holographic interferometry nakadate et al. During the reconstruction, the hologram is illuminated by the reconstructed wave u r x, y. At time t 2 the second holographic record is exposed by means of waves u 2 x, y and u r x, y.
Optical fibers profiling using interferometric and digital. Holographic interferometry and a related technique, speckle interferometry. Infrared holography in general, the refractive index of a plasma far from any. We propose a phaseshifting interferometry technique using only two inline phaseshifted selfinterference holograms. Phase shift differences of the reflected light are reconstructed exploiting the principle of doubleexposure holographic interferometry. They are full field noncontact experimental measuring techniques that allows rapid and.
Feb 09, 2019 optical interferometry is an effective accurate tool for studying and characterizing optical fibers. Holographic interferometry does not require machining or manufacturing of test section windows, mirrors or lenses with special precision or accuracy, because imperfections are. Replace the mirrors with two objects waves to obtain interference between them. This technique is called holographic interferometry hi. Fermats principle, lightinflight recordings, threedimensional measurements with ultrashort lightpulses and the special theory of relativity. According to the relationship between the reflection phase shift difference and the liquid index, two dimensional index distributions can be directly figured out, assuming that the index of air near the prism. Espi can be considered as the electronic version of holographic interferometry. Holographic interferometry method for assessment of static. It depends on the determination of the phase difference between a ray of light transmitting the fibers crosssection and a reference ray reaching the interference plane directly without crossing the fiber. Holographic interferometry method for assessment of. Holographic interferometry an overview sciencedirect topics.
The main difference between classical and holographic interferometry is that the object beam is compared with itself. Holographic interferometry by double exposure technique. Examples demonstrate the advantages of the techniques used. Rastogi, principles of holographic interferometry and speckle metrology, top. Interferometry by holography journal of applied mechanics. Simultaneous phase shifted digital speckle pattern interferometry. Firstly, the authors present the analysis of a small supersonic jet using three different optical techniques based on digital. There are diverse optical setups for dhi that enable the study of specimens in static and dynamic conditions. We discuss the general principle of holography and interferometry regarding measurements and analyses of phase distributions, first using the optical holography. View the article pdf and any associated supplements and figures for a period of 48 hours. Light in flight, digital specklepattern interferometry.
Holographic interferometry hi, which provides interferometric comparison of real objects or events separated in time and space, is a technique of unparalleled applications. The effects of class ii elastic force on a dry skull measured by holographic interferometry. Furthermore, hi can be performed with one, two, or more reference waves, which can be of the same or different wavelengths. Application of holographic interferometry for plasma. Types of holographic interferometry stored beam real time holographic interferometry. This means that the path difference between two incoming rays from points p and p will be 2dcos. High precision deformation measurement by digital phase. We present a widefield interferometric imaging module for biomedical and metrological measurements, employing shearing interferometry with constant offaxis angle sica that can work, for the first time, with a lowcoherence light source. Speckle and digital holographic interferometry a comparison. Holographic interferometry and its application in visualizing. The process of making a hologram is called holography. In dhi, the holographic images are formed from the superposition of the reference and object waves. Let us mark the time difference between the two exposures. Holography holography mathematics proposed by dennis gabor 1948.
Pdf lightinflight digital holography display ricardo. Holographic interferometry interferometry holography. The heat or mass transfer is then switched on, so that the momentary object beam experiences an additional phase shift. Komis optics and laser technology 1986 419 holographic interferometry applied at subfreezing temperatures. An optical measurement system using an offaxis method, which is a relatively new technique in the field of threedimensional measurement. However, depending on the type of analysis, the anatomical specimens must be fresh because macerated specimens will produce different results. Holographic interferometric study of heat transfer associated with a single vapor bubble sliding along a downwardfacing heater surface ht2003 laser interferometry hologram registration for threedimensional precision measurements. Holographic interferometry is a technique which enables static and. The distance between object points and the hologram plane does not appear in eqs. Applications of interferometry by measuring the distance between interference fringes, the path difference between the 2 light waves and hence the difference between 2 objects can be found out. Realtime color reflection holographic interferometry since transmission holograms are used, the diffraction efficiency of holograms just reaches between 10% and 20%, which limits the quality and the contrast of interferences fringes. Pdf dualwavelength imageplane digital holography for. The incident angle difference between the two waves results in a fine fringe pattern, and the image sensor records a single offaxis hologram. Macro to nano specimen measurements using photons and.
A laser is needed to produce a coherent, monochromatic light beam. Synthetic aperture radar differential interferometry. Digital holographic interferometry with co2 lasers and. A phase difference between the two holograms indicates a temperature variation, and it is possible to obtain the temperature value at each small point of the sensed optical field. The proposed technique adopts a mathematical model for selfinterference digital holography. Frontiers lowcoherence shearing interferometry with.
Realtime holography is a second method of creating holographic interferograms. Ndt nondestructive testing, for example comparison of the deforma tion fields of two. Interference and interferometry in electron holography. Between the reflection and transmission types of holograms, many variations can be made. Figure 2 shows a difference between holographic and shearographic nondestructive testing.
Application of holographic interferometry for plasma diagnostics. However, the requirement for a dynamic measurement is slightly different than that used for surface contouring a 103 or 104 order of multiplication in wavelength is normally required. In phase shifting interferometry, a reference wave front is moved along its propagation direction respecting to the probe wave front changing with this the phase difference between them. Digital holography and its multidimensional imaging.
Embossed holograms to mass produce holograms for authenticity applications such as security hologram stickers or the holograms you find on on credit cards, currency and passports, a twodimensional interference pattern is pressed onto thin plastic foils. This is a technique used to compare a hologram with the live object. They may be therefore applied either to an offaxis hologram or to an imageplane hologram. A first exposure records the object in an unstressed state. In the former the undistorted object wave, called the comparison wave, is stored on a photographic plate and can be reconstructed after its development then it is called hologram by an illumination. May 11, 2014 3 recording holograms of the bottom of a 35 mm film can while it was vibrating. Difference holographic interferometry dhi can be used for direct optical comparison of two nominally identical objects master and test and gives the results of the comparison in the form of an interference pattern displaying the difference in deformation, shape, or refractive index distribution change of the two objects. Time averaged we will now look at these three types. However, while these methods give extremely accurate values of optical phase, the heterodyne holographic interferometry3 4 is limited to point. Fourdimensional hologram interferometry for automatic detection of oil spills. Suppression of dc term in fresnel digital holography by. Digital holographic interferometry in the longwave infrared domain has been developed by combining a co2 laser and a microbolometer array. Computational denoising based on deep learning for phase.
Pdf holography and holographic interferometry with a near ir. Comparison of the suggested technique with conventional holographic inter ferometry shows its reliability for localizing defects. A beam from a laser 1001 is divided into a reference beam 1003 and an object beam 1007 by a half mirror 1002, and the reference beam 1003 travels to a detector 1006 via a mirror 1004 and a half mirror 1012, and the object beam 1007 is, go to the object. Digital holographic interferometry dhi provides an interferometric comparison of objects or events separated in time and space.
Twowavelength holography and phaseshifting interferometry are combined to measure the phase contours of deep wavefronts and surfaces, such as those produced by aspherics, with a variable sensitivity. Simultaneous phase shifted digital speckle pattern. Interferometer ii the phase difference between the two arms is changed by the presence of the plasma. Later, in april 1965, stetson and powell obtained realtime interference patterns between a real object and its holographic reconstruction. Holograms are created by the technique of physics known as holography. What is the differences between digital speckle pattern. Theoretically the smaller the difference between two wavelengths, the larger the synthetic wavelength allowing a higher velocity to be detected. Digital holography is applied to measure shape and surface deformation of opaque bodies and refractive index. Keys so as to understand the differences between digital holography and speckle interferometry and examples of software for hologram reconstructions are also treated in brief.
Inclassicalinterferometry1,several configurations exist but generally one considers. Therefore, holographic and machzehnder interferometry differ from each other in such a way that the first is a twostep method see figure 2 and the second is a twoway method. The composite image depicts the difference between the stressed and unstressed states. The long wavelength allows large deformation measurements, which are of interest in the case of large space reflectors undergoing thermal changes when in orbit. There is no requirement for additional recording or estimation in the measurement. Compare the requirements on the light sources, the optics needed to record the image, the physical quantities that are recorded, and how and what kind of information about the object can be reconstructed. Place the reflection hologram in the white light beam. All two beam interferometers rely on constructive and destructive in terference to give fringes.
In the sica module, the shearing distance between the interfering beams can be fully controlled without a direct relation with the offaxis angle. Pdf optical tomography and digital holography julia. Introduction dennis gabor invented holography in 1948 as a method for recording and reconstructing the amplitude and phase of a wave. Analysis in digital holography under the supervision presented by of b. Assuming that a specimen has a delamination, a sufficient loading, e. Digital holographic reconstruction and optical tomography was the theme of an international workshop 8 held in loughborough in 2007, and many of the topics debated at the workshop have become the subject of the papers in this issue. Figure 6 shows a comparison of 2d temperature fields acquired by dhi left side of. Holographic interferometry has displaced machzehnder interferometry completely due to its greater cost effectiveness, simplicity of operation and convenience. Holographic interferometry light from the original hologram playback is u3.
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