The contrast degradation due to tilt between exposures limits the amount of tilt, the number of fringes and the spatial resolution. The effect was derived quantitatively and verified experimentally. Mutual influences between system parameters cause ambiguity in the measurement results. The main effects are imaginary displacement resulting from combined deflection and initial slope, and imaginary strain resulting from deflection. These effects were demonstrated experimentally. Formulas were developed that enable the designer of the experiment to choose the desirable parameters of the set-up. They point out the difficulties in using the method in ‘field measurements’, primarily because of the finite dimensions of the lens and the photographic plate.

This paper presents a qualitative and quantitative analysis of timeaveraged projection moire vibration measurements for a plate and a cylindrical shell. It is pointed out that although moire fringes are generally considered to represent a constant contour difference or constant vibration level, in practice, variations in local grid pitch values on the test-item surface result in wide variations in measured displacement levels for given fringe numbers, which must be taken into consideration for quantitative evaluation.

A method was developed for analyzing modes and amplitudes of vibration of a randomly excited object. Time-average holography, in which the reference beam was mechanically excited at any given frequency in the spectral range of the random excitation, was applied. The phase of the exciting vibration of the reference beam was locked to the phase of the specific frequency in the random band. This method was applied as successfully as for objects excited with swept sinusoidal vibration.

We describe a new method, based on projection moire, in which fringes relate directly to the second derivative of displacement. The method was applied to a cylindrical shell segment. The experimental results obtained with the new method were found to be in good agreement with strain gauge measurements.

Time-averaged moire fringes may be produced by projecting a grid onto a vibrating test item surface using a conventional (2 in. x 2 in.) slide-projector and recording with a 35-mm SLR camera. Quantitative analysis of the resultant fringes is generally performed with the help of equations developed by time-averaging the optical intensity of the projected grid throughout the vibration period of the test item surface. In the present paper the authors present a physical description for the production of time-averaged moire fringes involving the splitting of grid lines resulting from their behavior as simple harmonic oscillators. Superimposition of vibrating grid lines produces blurring of the photographic image; regions of zero-amplitude vibration (nodes) may be identified by the clarity of their grid lines, enabling the analysis of mode shapes from the photographs.

When a focused beam with a Gaussian profile impinges a surface, the reflected beam is sensitive to a macroscopic wavelength Lambda = Lambda (Deltaz,omega(0),n), where Deltaz is the out-of-focus distance, omega(0) is the diameter of the beam in the focal region, and n is the index of refraction of the media. However for n = const, we have found that Lambda = const, certifying such optical surface height measurements. The phase variations of the reflected beam were calculated for changes in the complex index of refraction for several metals and dielectric materials, demonstrating the possibility of distinguishing between various metals when their surface profiles are below the measuring limit of the instrument.

Rasterography was developed for measurements of three-dimensional surface height distribution. It is extended here to the measurement of strains due to changes in curvature under an object's deformation. The method is demonstrated for a cylindrical shell segment under static loading. However, the method is general in that it can be applied for any curved surface loaded statically.

Single frame close-range photogrammetry was combined with white light projection moire for analysing mechanical properties of a cylindrical shell segment (css). Computer processing methods were developed for measuring and calculating the changes in the radius of curvature and strains due to its static loading.

A new physical explanation for the operation of the Orbitron maser is presented. The Orbitron experimental results are shown to be in agreement with the prediction of the theory of amplification by stimulated emission of bremsstrahlung.

An instrument for surface profile measurements without need of a separate reference surface is presented. Height variations of 50 Å can be resolved, while the theoretical height resolution is 4 Å. The lateral resolution is 3 μm, which also can be improved. Scan lengths of 100 μm to several millimeters are achieved, and no extensive alignment of the sample is needed. The instrument is a heterodyne interferometer, and the sample is used as a reference surface.

The quality of the first-order diffracted laser beam that emerges from an acousto-optic light modulator has been studied, while changing the diameter and the convergence of the incident beam.

An automatic system is described for the measurement of intensity distribution of millimeter electromagnetic waves propagating inside a hollow conducting pipe, whose diameter is larger than the free space wavelength. A miniature glow discharge tube served as the millimeter wave detector. This tube offers many advantages over solid state detectors in applications for systems of the kind described here. A mechanical apparatus moved the detector along a spiral trajectory, which is suitable for round pipes. The position of the detector was traced by an optical chopper. A microcomputer was applied for controlling the movements of the mechanical apparatus collecting the data from the detector and storing it for further analysis. Pictures of the millimeter wave intensity were obtained on a small printer controlled by the microcomputer.

This letter presents a method for the analysis of stiff density fields in which weak density gradients as well as strong ones, pointing in different directions, exist. Holographic techniques are used to freeze the deviated rays of a collimated beam traveling through a phase object. The hologram is post analyzed by the ‘‘moire deflectometry’’ method, where the sensitivity, the spatial resolution, and the direction along which the density gradients are measured, may easily be changed and adjusted to the different density regions in the field. It was found that this technique is very useful for short duration stiff fields where density mapping during one pulse is desired.

An extension of [1] to measurement of vibrating modes of an object using holographic spectroscopy is given. The calculation of the average irradiance for a random vibrating object considering different conditions of the reference beam is described. The details of the experimental setup based on a phase locking principle is proposed.

Measurements were taken in order to compare “spatial frequency response” (SFR) and resolution properties of several types of holographic methods. The best SFR was obtained for the “Fourier holographic method”; good resolution and SFR were also found for the “image plane hologram” (IPH) reconstructed with a laser light.