Publisher Summary This chapter discusses the nature of the speckle pattern and defines some of its basic characteristics. The speckle effect in optics is the generation of a random intensity pattern formed when coherent light is scattered by a rough surface or is diffused by a medium containing scattering centers. The chapter concentrates on the instrumental aspects of speckle interferometry and their applications rather than a detailed theoretical treatment. It is seen that a considerable degree of ingenuity has had to be employed to overcome the inherent difficulties that occur when interference takes place among randomly distributed phase fields rather than among smoothly varying ones. Although the aim of the research is to develop techniques useful to the engineer, developments are also being made in the use of speckle patterns for information processing, where the pattern is employed as an optical carrier.

IV Speckle Interferometry

Publisher Summary This chapter focuses fringe formations in deformation and vibration measurements using laser light. The chapter discusses a survey on the formation of the fringe patterns observed in these methods. The chapter helps in deriving dependences of their shape and visibility on object deformation parameters and optical systems by starting from the correlation properties of the light scattered from diffuse objects, and discuss the mutual relationships and features of each method by putting physical interpretations on derived mathematical relations. In holographic interferometry and speckle interferometry, the fringe shape represents the distribution of the phase change of the scattered light caused by object deformation, while the fringe visibility depends on the overlap of the corresponding speckle pair, therefore, on speckle displacement and speckle size. In speckle photography, on the other hand, the fringe shape represents the speckle displacement, while the fringe visibility is affected by the speckle decorrelation accompanying the displacement. In addition the relations derived in the present chapter would deliver a quantitative basis for selecting an adequate method of measurement and the optimum manner of signal processing in these modem interferometric techniques.

V Fringe Formations in Deformation and Vibration Measurements Using Laser Light

Speckle shear interferometry is used for measuring the tilt of diffuse objects with high sensitivity. The theory of tilt measurement using rotational, inversion, and folding shears is given, and experimental results are presented. Experimental configurations to achieve both inversion and folding shears simultaneously are given.

High sensitivity tilt measurement by speckle shear interferometry.

Speckle Shear Interferometry—A Review

Chapter 8 – topological speckle and structures inspection

The dielectric constant, pyroelectric coefficient, and loss tangent of triglycine sulphate (TGS) crystals that had been poled and subsequently irradiated with x-rays are presented as a function of x-ray exposure and temperature. The results are compared with similar measurements made on poled Co 60 gamma irradiated TGS. An estimated x-ray dosage of 1.5−2.0 × 10 6 R min -1 for 1–2 min gave equivalent results to 2.3 Mr of Co 60 gamma rays in achieving optimum non-ferroelectric pyroelectric in TGS ir detectors.

H.P. Beerman

Papers

Permanent polarization in pyroelectric TGS in detectors due to x-rays