This is accomplished with holographic interferometry, wherein interferometry is carried out with holographically generated wavefronts 3. Unlike ordinary photographs, holograms record both phase and amplitude information. A hologram is a photographic recording of a light field, rather than an image formed by a lens. Figure 8 holographic setup for ambient light effects test 19 figure 9 shutter assemblyambient light effects test. Optical holography is a method for storage and displaying a threedimensional image of an object. Introduction to ndt by active infrared thermography1. Measurement of internal strainstress fields by means of. Indeed, shearography can be employed in fieldfactory settings. Hence holographic nondestructive testing hndt can be used wherever the presence of a defect results in change of local deformation of the stressed. The simplest and most accurate way of testing materials and components is often to test them to destruction. It can be possible when it is applied the non destructive testing ndt by digital holography dh, which mean it is going to be explained afterwards. This course presents the basic principles of the techniques for noncontact measurement and non destructive testing which are based on holographic. Laser light, with appropriate optical equipment, can produce accurate, noncontact methods of measuring size, position, spacing, etc, or measure very small displacements of a surface. The first part of this paper reports progress to date on an experimental investigation of the feasibility of applying holographic techniques to acoustical imaging to obtain threedimensional images of opaque objects as encountered in nondestructive testing.
Application of pulsed laser holography to nondestructive. Holographic and laser speckle methods in nondestructive. Ultrasonic holography in nondestructive testing springerlink. New holography technology all ppt linkedin slideshare.
For instance using arrays of temperature sensors, such as thermocouples or through the use of liquid crystal paints 2, 3. It thus allows reconstruction of the full 3d image of the object. Holographic nondestructive testing by an optically generated zone plate n. Microwave holography for ndt of dielectric structures. Some results will be reported which have been obtained at the lower surface of an aerofoil, on a wheel well and on an airbrake. Nondestructive holographic techniques for structures. Holography and holographic interferometry as a means for nondestructive testing, as well as metrologic tools in engineering, biology, and other fields, have significant momentum by the introduction of digital holography dh and further by the employment of numerical processing power, which became available due to the increase in speed and data capacity of modern computers. The first part deals with the theory of holographic imaging, the characteristics of the reconstructed image and the different types of holograms. Contents 1 introduction 2 2 the development of optical holography 4. I describe its historical development, its basic principles and some examples of its practical application in optical systems. Request pdf application of digital holography for nondestructive testing and metrology holography and holographic interferometry as a means for. Purchase holographic nondestructive testing 1st edition.
Particular attention is given to the identification of stressed areas, the study of debonds in laminated structures, and vibration analysis. Lti is the world leader in industrial laser shearography and holography ndt services and equipment for the aerospace, military, aircraft, automotive and marine industries. Infrared holographic interferometry for metrology of space. Ultrasonic holography is being evaluated principally on behalf of the nondestructive testing centre at harwell to determine its usefulness in the field of nondestructive testing. Optical holography is an imaging method, which records the amplitude and phase of light reflected from an object as an interferometric pattern on film. Destructive testing is used in aerospace to determine the. Application of digital holography for nondestructive. Acoustical holography, which first appeared in the 1960s in studies in ultrasonics, is an outgrowth of optical holography, invented by dennis gabor in 1948. Sme development of holography system and applications innov support sme servicing partner. The objective of optical holography is to observe reconstruct threedimensional images of the sources of reflected light. Holography, means of creating a unique photographic image without the use of a lens.
If two light wavefronts are traveling and pass a given point, the total intensity is given by the algebraic sum of the intensities of the individual wavefronts. Abstract the article outlines the basic principles of holography as applied to nondestructive testing. Holography is the science and practice of making holograms. Shearography is noncontact ndt inspection method used for the detection of subsurface defects such as voids, delaminations and unbonds in. Since a long coherence length source is needed to record a hologram of an object, holography remained.
Applications of ndt methods on composite structures in. Holography is a two step process of recording a wavefront and then reconstructing the wave 1. Lti manufactures laserbased shearography, holography and ndt systems and provides ndt testing services and level ii and iii training. Therefore it is important to first understand the principle of superposition and interference of waves.
Wholefield ndt of porous materials using digital holography core. Non destructive testing ndt is a noninvasive technique for determining the integrity of a material, component or structure. Chief, ndt and mechanics branch metals and ceramics division i. This book presents a selfcontained treatment of the principles, techniques and applications of optical holography, with particular emphasis on recent developments. Finally, laboratory investigations of holographic nondestructive testing.
Pdf holographic nondestructive testing by an optically generated. Holographic interferometry combines both threedimen sional laser holography and laser interferometry into a power ful ndt technique able not only to detect. In hndt, the test sample is interferometrically compared in two different stressed states. Review of pulsed holography in nondestructive testing. Holography 1 holography introduction and background the aesthetic appeal and commercial usefulness of holography are both related to the ability of a hologram to store a threedimensional image. This site is like a library, use search box in the widget to get ebook that you want. The book discusses in detail the basic theoretical concepts, the experimental methods for recording holograms, and different specialized holographic techniques. In each of the samples tested, the holographic method was successful and although the tests were. The next section covers the practical aspects of holography optical systems, light. Acoustical holography accessscience from mcgrawhill. This kind of studies are used in aircraft industry like is explained afterwards in the brief history of the holography.
The photographic recording of the image is called a hologram, which appears to be an unrecognizable pattern of stripes and whorls but whichwhen illuminated by coherent light, as by a laser beamorganizes the light into a threedimensional representation of the original object. While holography is often used to obtain the recreations of beautiful 3dimensional scenes, there are several engineering applications, the most common and important one being holographic nondestructive testing 2. Laser ndt methods based on interferometic imaging, primarily holography and shearography have seen growing acceptance since the mid 1980s. Pdf holography is the science of making holograms which are usually intended for displaying three dimensional images.
Non destructive testing ndt is a way to detect and evaluate flaws in materials. Holographic and shearographic ndt applications in aerospace manufacturing. When reconstructing the original wavefront from the recording, a three dimensional image is observed. Holography was born out of a challenging technological problemthe need to improve the resolution of the electron microscope, which was limited by the spherical aberration of the electron lenses. Equipment was fabricated to make acoustical holograms of objects in water. Application of digital holography for nondestructive testing and. Holography is a technique whereby one wavefront can be recorded and subsequently reconstructed without the presence of the original wavefront. Non destructive testing ndt methods, or nondestructive inspection ndi methods, are applied to determine the physical condition of an object, performed in a way, so that it is not altering or permanently changing the properties of the object 2. Nondestructive testinginspection of composite materials.
It is a versatile technique, for example it gives as much qualitative visualisation for non destructive testing as it does for the stalling of engines. The wave nature of both light and sound make holography possible. Holography provided excellent disbond detection with easily interpreted images essentially identical to ut results, but not affected by part geometry. Laser testing methods lm such as holography, shearography and profilometry for highspeed and largearea inspection especially of composite materials. Optical and acoustical holography download ebook pdf. Holographic nondestructive testing presents a unified discussion of the principles and methods of holography and its application holographic nondestructive testing.
Pdf microwave holography for ndt of dielectric structures. The theory behind the recording and reconstruction of object wavefront is well documented 1,2. Leak testing at level 2 vienna, 2012 training g uidelines in n on destructive testing techniques. This paper will present an overview of laser ndt technique applications in aerospace, electronics and marine composites, where they serve as highly effective, fully integrated industrial process controls, improving. Nondestructive testing ndt is the process of doing inspections, testing, or evaluating materials, components or assemblies for defects without destroying the material or component. Holography is often used to obtain the recreations of beautiful 3dimensional scenes, there are several engineering applications, the most common and important one being holographic nondestructive testing 2. These measurements can be applied to stress, strain and vibration analysis, as well as to non destructive testing and radiation dosimetry. Finally, laboratory investigations of holographic nondestructive testing procedures as applied to composite compressor blades are described in section vi. 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. Holographic nondestructive testing 1st edition elsevier. A hologram is a physical recording of an interference pattern which uses diffraction to reproduce a threedimensional light field, resulting in an image which retains the depth, parallax, and other properties of the original scene. Because phase is a relative property, construction of a. Within aerospace ndt plays a vital role in the design, manufacture and maintenance of aircraft. Unlike holography, shearography does not require a reference beam and hence it is more tolerable to environmental disturbances.
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