Federico M. Sciammarella

High-accuracy contouring using projection moiré

Shadow and projection moire are the oldest forms of moire to be used in actual technical applications. In spite of this fact and the extensive number of papers that have been published on this topic, the use of shadow moire as an accurate tool that can compete with alternative devices poses very many problems that go to the very essence of the mathematical models used to obtain contour information from fringe pattern data. In this paper some recent developments on the projection moire method are presented. Comparisons between the results obtained with the projection method and the results obtained by mechanical devices that operate with contact probes are presented. These results show that the use of projection moire makes it possible to achieve the same accuracy that current mechanical touch probe devices can provide.

Strain measurements in the nanometer range in a particulate composite using computer-aided moiré

When using metals and polymers in structural applications the macroscopic behavior depends on events taking place at levels in micrometer and nanometer ranges. At this range, material behavior, phenomena such as plasticity and fracture are size-dependent. We discuss these phenomena with regards to the case analyzed in this paper. Continuum mechanics flow theory of plasticity cannot explain the failure behavior of a particle-reinforced aluminum composite. An experimental study of the strain field in the micrometer range provides an explanation of the earlier than expected failure of the composite. We give a detailed description of the optical technique used to make the experimental mechanics measurements.

Measurement of mechanical properties of materials in the micrometer range using electronic holographic moire

Measuring mechanical properties of specimens whose dimensions are in the range of micrometers poses a number of difficult and interesting problems. Currently there are a number of developments in this area, especially in connection with microelectromechanical systems (MEMS). Electronic holographic moire is an ideal tool for micromechanics studies. It does not require a modification of the surface by the introduction of a reference grating. This is of particular value when placing a reference grating becomes a difficult task. Traditional electronic holographic moire presents some difficult problems when large magnifications are needed and rigid body motion causes the loss of the correlation fringes. We present developments that solve these problems and extend the application of the technique to micromechanics.

Extension of electronic speckle correlation interferometry to large deformations

The process of fringe formation under simultaneous illumination in two orthogonal directions is analyzed. Procedures to extend the applicability of this technique to large deformation and high density of fringes are introduced. The proposed techniques are applied to a number of technical problems. Good agreement is obtained when the experimental results are compared with results obtained by other methods.

Optical Holography Reconstruction of Nano-objects

The continuous growth of many fields in nanoscience and nanotecnology puts the demand for observations at the sub-micron level. Electron microscopy and X-rays can provide the necessary short wavelengths to gather information at the nanometer and sub-nanometer range but, in their current form, are not well suited to perform observations in many problems of scientific and technical interest. Furthermore, the environment required for the observation via X-rays or electron microscopy is not suitable for some type of specimens that it is necessary to study. Another concern is the changes that may be induced in the specimen’s structure by the utilized radiation. These issues have led to the return to optics and to the analysis of the optical problem of “super-resolution” , that is the capacity of producing optical images beyond the classical diffraction limit. Classical optics has limitations on the resolution that can be achieved utilizing optical microscopy in the observation of events taking place at the sub-micron level, i.e. to a few hundreds of nanometers. To overcome this limitation and achieve super-resolution, non conventional methods of illumination such as evanescent waves are utilized. The initial approach to the utilization of evanescent field properties was the creation of near-field techniques: a probe with dimensions in the nano-range detects the local evanescent field generated in the vicinity of the objects that are observed. A perspective review on superresolution can be found in Sciammarella (2008). New methods recently developed by C.A. Sciammarella and his collaborators (see, for example, Sciammarella, 2008; Sciammarella et al., 2009) rely on the emission of coherent light by the objects that are under analysis. This is done through the phenomenon of light generation produced by electromagnetic resonance. Object self-luminosity is the consequence of electromagnetic resonance. Why self-luminosity may help to increase resolution? The light generated in this way has particular properties that are not present in the light sent by an object that results from external illumination. The produced wave fronts can travel long distances or go through an optical system without the diffraction changes experienced by ordinary wave fronts (see, for example, Durnin et al., 1987; Buchal, 2003; Gutierrez-Vega et al., 2001; Hernandez-Aranda et al., 2006).

Heisenberg principle applied to fringe analysis

Optical techniques that are used to measure displacements utilize a carrier. When a load is applied the displacement field modulates the carrier. The accuracy of the information that can be recovered from the modulated carrier is limited by a number of factors. In this paper these factors are analyzed and conclusions concerning the limitations in information recovery are illustrated with examples taken from experimental data.

Processing of a Hrtem Image Pattern to Analyze an Edge Dislocation

Dislocations were introduced in the theory of Elasticity to evaluate the possibility of multiple values in displacement fields. The initial work was done by Volterra [1] in the 1900’s who came with the basic types of dislocations that currently are used in theoretical elasticity. The argument was further elaborated by Love [2] in the 1920’s. In the 1930’s, dislocations re-appeared as an argument to explain the actual behavior of crystals upon deformations compared to theoretical results coming from crystalline structures [3, 4, 5]. In the 1960’s, using X-rays dislocations were visualized by reconstructing X-ray diffraction patterns. However, no efforts were made to numerically or analytically evaluate the observed patterns.

Electronic holographic moire in the micron range

The basic theory behind microscopic electronic holographic moire is presented. Conditions of observation are discussed, and optimal parameters are established. An application is presented as an example where experimental result are statistically analyzed and successfully correlated with an independent method of measurement of the same quantity.

Microscopic Electronic Holographic Moiré

The basic theory behind microscopic electronic holographic moire is presented. Conditions of observation are discussed, and optimal parameters are established. An application is presented as an example where experimental results are statistically analyzed and successfully correlated with an independent method of measurement of the same quantity.