Gravitational Field of a Spinning Mass as an Example of Algebraically Special Metrics

An Introduction to Coherent Optics and Holography

Interferometric hologram evaluation and real-time vibration analysis of diffuse objects

Application of moire techniques to holography

New methods are introduced that utilize interferometric comparison of images of diffusely reflecting objects from different hologram plates that are sandwiched together. To make the plate positions optically and mechanically identical during reconstruction and exposure, they are also exposed in sandwiches. If the two sandwiched hologram plates are separated by a small distance a new method of fringe evaluation can be used. Fringes caused by object tilt between two exposures can be eliminated by an analogous, but much larger, tilt of the sandwich hologram during reconstruction. Even the direction of tilt, forward or backward, is found this way.

Sandwich hologram interferometry : a new dimension in holographic comparison

Keywords: holographie ; mathematiques Reference Record created on 2005-11-18, modified on 2016-08-08

Holography and Deformation Analysis

Up to now, we have investigated, on the one hand, the kinematics of the deformation of a body (Sect. 2.2) and, on the other hand, the formation of holographic images (Chap. 3). In this chapter, these two subjects will be combined, because we are going to explain how holography can be used to measure deformations.

Chapter 4 Fringe Interpretation in Holographic Interferometry

1 Introduction- 2 Some Basic Concepts of Differential Geometry and Continuum Mechanics- 3 Principles of Image Formation in Holography- 4 Fringe Interpretation in Holographic Interferometry- 5 Second Derivatives of the Displacement and of the Optical-Path Difference- References- Author Index

Holographic Interferometry : From the Scope of Deformation Analysis of Opaque Bodies

As seen in Chap. 3, the principal property of holograms is the storage of wave fields which may be reconstructed at any later time. As was already mentioned in the introduction, it is for this reason that two slightly different wave fields, which do not exist simultaneously, may be brought to interfere. Analysis of the resulting interference fringes (Fig. 4.1) constitutes the principal problem in holographic interferometry, for which the first experiments were performed around 1965 [4.1–14]. In particular, if both wave fields are recorded successively on the same hologram (with the same reference source) and later reconstructed together, we obtain the well-known double exposure or frozen fringe effect. Using this technique, measurements are almost completely insensitive to small modifications of the optical set-up at the reconstruction, since both wave fields undergo the same small changes. Thus, the fringes disclose information about the difference of relative positions of the two (stationary) configurations from which these wave fields emanate. In this chapter, we shall investigate two cases of special interest in engineering. First, we present the elements concerning holographic determination of the deformation of an opaque body with a diffusely reflecting surface. Here, the concepts of Sect. 2.3 will be combined with those outlined in Sect. 3.1.1. Secondly, we intend to study holographic interferometry of phase objects, i.e., the determination of the spatial variation of the index of refraction of a transparent medium. This topic relates Sects. 2.2 to 3.1.1.

Holographic Interferometry or Fringe Interpretation

In a general view, a comparison is made of different optical methods where either photoelastic models, opaque bodies with transparent coatings or noncontacted objects are examined with coherent light. Further, it is tried to show that some common features are contained by the three groups. These aspects concern the separation, by controlled determination, of displacement, rotation and strain (or of certain of their components), the multiplication of the optical effects in the detection and the elimination of secondary influences. In particular, the noncontacting method of wavefront reconstruction with double-exposure holograms is discussed and the role of the localization condition for the fringes in space is analyzed. On the other hand, it is illustrated that, besides the generally known birefringence and diffraction. use could be made of nonorthodox effects like rotation of the plane of polarization, second-harmonic generation in nonlinear optics, etc. This may, for instance, contribute to the optical instrumentation when transparent models and bodies with photoelastic coatings are investigated under the above aspects.

Walter Schumann

Papers

Holography and Deformation Analysis

Chapter 4 Fringe Interpretation in Holographic Interferometry

Holographic Interferometry : From the Scope of Deformation Analysis of Opaque Bodies

Holographic Interferometry or Fringe Interpretation

Some aspects of the optical techniques for strain determination