Abstract Wavelength compensation for HOE has been investigated. The general equations for ray tracing through holograms are described. Using computer simulations, several HOE systems have been evaluated.

Non-destructive testing, particularly, in dynamical phenomena metrology, sensing, and control is a topic of major interest within optical metrology. Holography is rated as one of the most accurate techniques though of difficult practical implementation on industrial environment. Electronic holography or electronic speckle pattern interferometry (E.S.P.I.) is the credited alternative whenever lower resolution is not an impedement, and maximum advantages are to be gained from its TV based operating principle. A review is presented of improvements on E.S.P.I. techniques to further its technical capabilities and resolve some of the inconveniences of holography in industrial applications. Fibre optics was combined with synchronized amplitude and phase illuminating pulse modulation. Fringe enhancement was studied to remove coarsely appearance. Moire evaluation techniques were introduced for direct data extraction, increase of local sensitivity and reduction of inconveniences of high sensitivity of interferometric techniques.

The advantages of using optoelectronic techniques and the problems which need to be overcome when applying them in the field of measurement and inspection are reviewed. After a brief description of the basic methods and principles employed, typical systems recently developed at Sira using lasers, white light and infrared radiation for the inspection of large areas, microscopic defects and stress patterns are described to illustrate the range of new methods now available for use by industry.

This paper demonstrates through a collection of examples the practical application of laser and electro-optic techniques in industry. All the examples cited describe developments that Cambridge Consultants Ltd has carried out under contract to clients over the last five years. They demonstrate how a range of industrial problems have been solved where custom solutions based on laser and electro-optic technology provide the optimum answers.

Employing a tuff rock cave as the vibration isolation system made possible the measurement of the vibration mode of large-sized structure such as a fully equipped automotive bodies and producing 2 m by 1 m hologram for display.

This paper describes the technique of image derotation and its applications in several fields of mechanical engineering design including: 1. Flow Measurement of a Rotating Fan 2. Vibration Measurement of rotating engineering components using Pulsed Holography 3. Heat distribution visualization of rotating disc brake rotors Finally an account is given of the new method of T. V. Holography where high repetition rate pulsed lasers are combined with video cameras to provide holographic measurement of components in real time.

A survey of the most advanced optical experiments conducted with the help of lasers in the field of mechanics, aerodynamics and ballistics is given: flow visualization, studies of the deformation of materials and structures, vibration analysis, particle sizing and particle velocity analysis, laser velocimetry, shape measurements of 3 D-objects,... All these experiments are related to industrial problems and make use of pulsed lasers and cw-lasers with various techniques such as interferometry, cineholography, optical filtering, fiber optics, light-sheet illumination, etc...

Nondestructive testing (NOT) is usually used for determining, whether there is a defect in a material or not. Holographic interferometry by evaluation of the three dimensional deformation field gives additional information: Only flaws under tensile stress conditions influence the deformation field, but they are the critical ones. So, the holographic NDT is an absolute test method by taking into account the operational load. Furthermore, the evaluation of the three dimensional deformation field can be input to a FEM calculation in order to determine the internal stress distribution and to quantize the criticality of a detected defect, e.g. by adapting the ideas of fracture mechanics. The critical stress intensity factor KIc is a material property for crack propagation. The holographic interferometry is shown to be a good method to determine the KI-factor even for large test objects and without knowledge about the defect properties like size and location.

For years the development and testing of aero gas turbine engines has been hampered by the inability of engineers to penetrate the opaque casing walls and see and measure the growths, flexures and movements of the metal components and the fluid dynamic movements within lubrication systems in gas turbine engines. High Energy X-ray imaging has been developed to visualise and measure the movements of metal components and 'cold' neutron imaging to visualise and measure lubrication system dynamics. 'Direct' and 'Indirect' type intensifiers have been used and the research, development and application work is described. The radiation sources are described for x-rays and cold neutrons together with Oude Delft 'Delcalix' isocon based and Westinghouse Ebsicon based Indirect Imagers. Thomson CSF Direct Imagers for Low and High Energy X-ray and Neutron radiation are described together with a special Multispectral Imaging System for high Speed X-ray cine. Finally the application of the Kodak Spin Physics SP2000 with a Thomson tube for x-ray Imaging at 1000 pictures per second is described.

Holographic interferometry has provided the engineer with one of the most powerful and versatile measurement tools of the twentieth century. It seems only natural that such a technique should have found widespread application in the aero-engine industry. The quest for ever more fuel-efficient gas-turbine engines is constantly stretching and extending the frontiers of technology. It creates an increasing need for understanding of the mechanical and aerodynamic behaviour of components under extreme conditions. Holography has recently achieved new importance as a means of providing the data necessary for the development and validation of computer models. Increasingly, design work is being performed by the application of complicated three-dimensional computer models to gas flow prediction and the use of finite-element models for the investigation of mechanical behaviour and stress.

Examination of interior of cavities by holographic and/or speckle interferometry has been until recently of limited success because they all were based on conventional endo-scope principles, and, as a consequence, they had a restricted field of view. Cylindrical hologram recording techniques reconstruct images only from targets being inside, and not outside of the cylindrically folded recording medium, thus, the inner surface of the cavity cannot be measured by this technique. Using PDL optics developed at our laboratory the recorded cylindrical hologram reconstructs the entire inside of the cavity, thus, a 360° panoramic view of the interference fringes may be observed on the inside wall if double exposure technique was used, but even real-time holographic interferometry could be performed.

Three different examples for characterizing parallel-sided specimens with optical techniques are given; spectral emittance of an InAs specimen; AIRS (Angle of Incidence Reflectance Spectrometry) analysis of a III-V quaternary; calculations for AIRS measurerments on a silicon-like substrate having a relatively thick layer with a larger refractive index. Complete formulas ,along with appropriate approximations, are given. Starting with Maxwell's Equations, both the characteristic and Fresnel matrices are developed for the abrupt interface and homogeneous cases followed by indicated steps leading to the practical formulas. Also included is a discussion of dispersion and its relationship to the simultaneity of the duality of electro-magnetic radiation.

Conventional methods of experimental stress analysis are often subject to limitations when applied to the prototype. Plant shut-down, careful component surface preparation, and lengthy test procedures are costly in time and lost production. The measurement of in-plane strains on the component under service environmental conditions is therefore very attractive. Holographic techniques show promise and in particular 'Electronic Speckle Pattern Interferometry' (ESPI) displays considerable potential as a non-contact method of measurement of in-plane strain on rotating components.

Fundamentals of laser hologram interferometry and speckle metrology are reviewed with special emphasis on principles governing formation of fringe patterns and dependence of this phenomenon on object's motion and/or deformation. Processes relating to recording and reconstruction of holograms and specklegrams are discussed and are followed by presentation of procedures for their quantitative interpretation based on the method of projection matrices. Since there is a unique projection matrix for each hologram, or specklegram recorded from a different direction, each of the matrix equations relates the fringe parameters and recording geometry to the unknown deformation. Therefore, the resulting system of matrix equations can be solved for the unknown displacements, rotations, and strains.

The evenness of ultra-thin tungsten wires under 10.1Vm is one of the most important technical indices, the ensuring of which being a difficult problem in technology yet to be solved by the manufacturers. The paper presents in concrete a proposal for real-time laser and microcomputer system for controlling the process of producing ultra-thin tungsten wires under 10μm, based on in-situ investigations and researches. Laser ultra-thin wire dynamic metering device of type JXD-1 worked out here was used in combination with electrolytic ultra-thin tungsten wire polishing installation in an integral system, fully ensuring quality of the products by realizing real-time monitor and control of processing through dynamic mea-surements of tungsten wire on line and closed-loop feedback.' The paper deals with the principles of measurement on line and real-time control by means of the system and precision analyses have been made, multiple compensation of errors, controlling tolerance zone and other measures to guarantee precision and stability of the entire system. It is concluded that evenness of diameter of wire over its entire length is kept assuredly within the tolerance range when the aforesaid system is used in the production of ultra-thin tungsten wires under 10 Atm.

A new method stored speckle shearographic pattern in real time by means of 131 12 Si0₂₀ (BSO) crystals is reported. This speckle shearography can be applied to strain measurement and non-destructive testing in real time.

With the development of hydrostructural model test, it is necessary to find out a new measurement technique. Now the laser speckle technique is an effective non-touch measurement method, which can be used for both the Young's fringe analysis from point to point and the full-image analysis with high sensitivity but simple equipment in the laboratory. Since 1980, the authors of this paper have, repeatedly and systematically, applied the laser speckle photography method to the dam model materials and the linear and non-linear structural model tests of gravity dams. All the tests show that the relative error of displacement between the observation of laser and the dial guage is less than 4%. The data after observing the displacement of the triangular gravity dam from laser speckle method are considerably consistent with the results from finite element method. The error of them is less than 10%. The results of sliding model test of the simulating dam with the plaster block quite coinside with the calculation curves of the finite element method, in which the absolute error is 0.5-1.6 m. The results of the dam sliding model test of a given project made of geomechanical model materials by laser speckle method are approximately consistent with the data by the ordinary test method. The former final overloading coefficient of the dam is 17, and the latter is 20. Both the sandwich speckle method and the combined speckle method were presented here by the authors. All of the researches emphatically indicate that the laser speckle photography method for measuring two dimensional hydrostructural model test is full feasible and its precision is generally satisfied. Consequently, it is a non-touch measurement method, effective and useful, for the two dimensional geomechanical model test.

This paper presents analysis of the principles of photocarrier with application to photoelasticity, holography, and speckle. Photocarrier Modulation is a processing for the whole-field analysis in optically experimental mechanics automatically, demodulation is a procedure of image processing by a personal computer. Some applications and experimental procedure are shown by examples in different aspects.

Holo-speckle interferometry (HSI), as a 3-D displacement measuring method is studied in this paper. Three types of HSI are given. The average intensity distributions of its holographic and speckle interference fringes on the output planes are derived. The range of mea-surement and the problem of repositioning holograms for two-reference-beam HSI are disscussed. The results show that the upper limit of out-of-plane displacement is related to the parameters of the optical system and the in-plane displacement of specimen but the upper limit of in-plane displacement is determined by the paremeters only. The rigid body rotation of hologram in reconstruction process of two-reference-beam HSI influences the formation of interference fringes but the rigid body traslation does not have the influence.

A plate shearing interferometer can be used for measurement of the optical aspherical surfaces. Being common path this kind of interferometer is quite stable. The use of a plate shearing interferometer for fringe scanning interferometry is discussed. The phase shifting is provided by a new technique presented in this paper. It is shown theoretically and experimentally that this technique can be used for real time wavefront-aberration detection with greater pricision.

The paper deals with application of laser interferometry to NDT of tires by our research group during the past decade, stress being laid on non-destructive laser speckle shearing tire testers worked out recently, together with performance of its recording system, mechanical setup and microcomputer control system, and their practical application.