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The Laser Intensity Modulation Method (LIMM) is widely used for the determination of the spatial distribution of polarization in polar ceramics and polymers, and space charge in non-polar polymers. The analysis of experimental data requires a solution of a Fredholm integral equation of the 1st kind. This is an ill-posed problem that has multiple and very different solutions. A number of methods have been used to solve this problem. In this paper, a comparison is made among three different techniques: the Scale Transformation Method, the Polynomial Regularization L-Curve Method and the Monte Carlo Method. The accuracy and ease of use of the three techniques are compared using both simulated and experimental data. Index Terms--Fredholm integral equations, intensity modulation, Monte Carlo methods, polarization, pyroelectricity, semiconductor lasers.

Thermal diffusivity by laser intensity modulation method (LIMM-TD) was used for the measurement of thermal diffusivity of thin solid samples. Results suggested high thermal conductivities of the poled lead-zirconate-titanate ceramic (PZT) materials due to the presence of the poling fluid.

Pyroelectricity, one of the least-known properties of solid matter and the pyroelectric effect are both defined and explained in detail. The historical evolution in the study of pyroelectricity and the practical application of pyroelectric IR detectors in various fields are discussed.

The Laser Intensity Modulation Method (LIMM) is widely used for the determination of the spatial distribution of polarization in ceramics, single crystals and polymers. A brief history of the origin and development of LIMM during the past 20 years is presented. The experimental technique and the derivation of the LIMM equation are described. The data analysis requires the numerical solution of a Fredholm integral equation of the 1st kind. This is an ill-posed problem that has multiple and very different solutions. In this paper, a new technique is proposed that gives the polarization distribution in the form of a special 8th-degree polynomial. Both simulated and experimental data are analyzed with the new technique. Index Terms--Ferroelectric, polarization distribution, pyroelectric coefficient, ceramics, polymers, regularization.

Research shows that triglycine sulfate-gelatin (TGS-gelatin) films grown in a solution contining gelatin and TGS need water to exhibit pyroelectric and dielectric film properties. The dependency relationship is based on superionic conduction of the film gelatin phase. Dry films have lower pyroelectric coefficients and lower coercive fields than wet ones. Increasing water content is causes increased dielectric permittivity. Electric double layers are created at the electrode film and TGS crystallite-gelatin phase interface following water absorption.

Pyroelectricity is the electrical response of a material to a change in temperature. It exists in polymers which contain spontaneous or frozen polarization resulting from oriented dipoles. This review describes the physical basis for the existence of the pyroelectric effect and discusses its behavior in a number of amorphous, semicrystalline, crystalline and liquid crystalline polymers. Some of the techniques for measurement of the pyroelectric effect are presented and its use in pyroelectric relaxation spectroscopy and thermal analysis is described. The spatial distribution of polarization and space charge through the thickness of polymer films can be determined by several thermal pyroelectric techniques. Recent developments in the integration of pyroelectric polymer infrared detectors with solid-state silicon devices are described. One of the most important recent applications of polymers is in photopyroelectric spectroscopy which can be used for the determination of a number of thermal and optical properties of materials. Finally, some miscellaneous applications in physics, chemistry and biology are presented.

Two different methods of measurement of polarization distributions in piezoelectric materials, the LIMM and the PWP method, are compared. After briefly describing the two techniques, we report measurements made on different PVDF based samples, one with a symmetric and the other one with an antisymmetric structure. Although the LIMM responds to diffusion of heat and the PWP method to the propagation of a pressure wave, the direct observation of the raw data gives similar information in both cases as far as the symmetry of the polarization distribution is concerned. Then we analyze the specific characteristics of each method.

Presents a study which developed laser-intensity-modulation method (LIMM), a method for measuring the spatial distribution of combined polarization and space charges in poled polymer electrets. Outline of the method; Mathematical basis of LIMM; measurement procedure and analysis of the distributions.

Many thousands of papers have been published on the piezoelectric, pyroelectric and ferroelectric properties of single crystals, ceramics, polymers and liquid crystals. Yet fewer than 100 papers have appeared on these properties in biological materials. Piezoelectric and pyroelectric effects have been measured on a number of plant and animal tissues and the possible existence of ferroelectricity has been suggested also. This paper reviews some measurements and speculates on their significance. Specific examples include piezoelectricity in a crystalline material in the pineal gland of the brain, pyroelectricity in the heat sensing organs of certain varieties of snakes and beetles, and ferroelectricity in the conduction of action potentials in nerve and muscle cells.

Dilip Kumar Das-Gupta was a specialist in the field of dielectric materials research and discovered the electric-field-induced crystalline phase of the semicrystalline ferroelectric polymers. He also introduced the laser intensity modulation method for probing dielectric films.