Using the atmospheric modulation contrast function area (MCFA) as a single-valued numerical criterion for image quality propagated through the atmosphere, a statistical study of atmospheric imaging data has led to the determination of regression coefficients with which to quantitatively predict, at visible and near-infrared wavelengths, effects of wind speed, air temperature, and relative humidity on image quality propagated through the atmosphere as functions of wavelength and of spatial frequency. Utilization of this procedure is quite simple: one merely plugs expected values for wind speed, air temperature, and relative humidity into the regression coefficient expression for the MCFA. The larger the expected MCFA, the better the expected image quality. Models are presented for desert and nondesert atmospheres. Preliminary experimentation indicates that the accuracy of the models is quite good and that the quality of image propagation through the atmosphere can be described as a simple function of basic macroscale meteorological dependences previously unknown. These fundamental meteorological parameters are part of weather forecasts measured worldwide, are simple and inexpensive to measure, and also can be used to determine the overall atmospheric modulation contrast function as a function of spatial frequency and meteorological conditions. An important advantage of this new approach is its simplicity as well as its accuracy.

By using a defocused optical field with a Ronchi grating to get a quasi-sine optical field and by using a grating ii phase shifting technique, the fundamental spectrum modulated by the object height distribution can theoretically be extended from 0 to 2f0 ( f0 is the carrier frequency of the optical field) without overlapping the zero component and other higher spectra. Consequently, the measurable slope of height variation can be extended to nearly three times that of the unimproved Fourier transform profilometry method. This paper gives the theory and experiment results of the improved Fourier transform profilometry.

One of the critical questions regarding radiation thermometers is how to obtain the true temperature of an emitting opaque body with an unknown emissivity and with unknown circumferential radiations. We suggest that two enclosed chambers with given temperatures and emissivities be used to cover part of the area of the emitting body. By use of two simultaneous radiothermometer readings, both the true temperature and the emissivity of the graybody can be calculated.

A system for associative object recognition of learned objects by hierarchic template matching is presented. It is problem independent to some extent. It is able to classify and recognize objects that are taken by a TV camera in front of a known background scene. The hierarchic steps are as follows: separation of object and background, object normalization, classification, and individual recognition. For classification each template is an archetype constructed from the learned objects of one class. Three kinds of archetypes with respect to their classification efficiency are investigated.

In this paper, methods for reducing the computational load of an adaptive iterative image restoration algorithm while producing a restored image of high visual quality are proposed. These methods are based on a class of iterative restoration algorithms that exhibit a first- or higher-order convergence, and some of them consist of on-line and off-line computational parts. Since only the first-order or linear algorithm can take a computationally feasible adaptive formulation for image restoration, iterative algorithms that combine the linear and higher-order algorithms are proposed. These algorithms converge to the weighted minimum norm least-squares solution with significantly less computational load cornpared to the adaptive linear algorithm. The quality of the adaptively restored image depends on the choice of the weight coefficients, which are evaluated based on the spatial activity of the image. Various methods for computing the local spatial activity in the image are proposed. These methods are shown to produce visually better restoration results. Also, a method for computing the weight coefficients only at the edges is proposed, which results in additional computational savings. Finally, experimental results are presented and the various restoration methods are compared with respect to their computational complexity, the mean squared error, and the visual quality of the restored images.

This paper deals with the correction ofthe distortion of magnetic resonance pictures due to the presence of bulky stereotactic surgical equipment or other kinds of ferromagnetic perturbation. The distortion is measured over a ring of calibration rods distributed around the patient's head. This boundary information is used to correct the distortion all over the transverse scan plane. The unique feature of the proposed approach is that the error all over the transverse plane is bounded by the error around the ring of rods. This is accomplished by making use of subharmonic functions.

The objective of a number of optical instruments is to measure the intensity accurately without bias as to the incident polarization state. One method to overcome polarization bias in optical systems is the insertion of a spatial pseudodepolarizer. Both the degree of depolarization and image degradation (from the polarization aberrations of the pseudodepolarizer) are analyzed for two depolarizer designs: (1) the Cornu pseudodepolarizer, effective for linearly polarized light, and (2) the dual Babinet compensator pseudodepolarizer, effective for all incident polarization states. The image analysis uses a matrix formalism to describe the polarization dependence of the diffraction patterns and optical transfer function.

Digital image processing and pattern recognition have become important tools in experimental stress analysis. Fringe interpretation and digital autocorrelation are the two prominent examples where digital image processing has significantly influenced experimental research. This paper discusses the use of digital image processing in concert with the grid method. Presented here is a start-to-finish analysis of grid point tracking with image acquisition hardware and pattern recognition software. A mathematical model, which is based on experimentally controllable parameters, is used to simulate the video camera and analog-to-digital conversion. A simple centroid algorithm is used to track the grid points. The model results, which are reaffirmed by rigid body motion tests, show that the fill factor, signal-to-noise ratio, and grid spot diameter govern the accuracy of this automated grid method. Finally, the model shows that the intensity profile of the individual grid spots has a significant impact on the maximum allowable grid frequency, camera field of view, and the overall acëuracy of automated grid methods.

A review of research conducted at the Naval Research Laboratory illustrates the unique advantages of using lasers to probe the newly formed gaseous products from chemical reactions on surfaces. Examples to be discussed are taken from the areas of catalytic reactions, silicon etching, and surface photochemistry. UHV experiments on the catalytic oxidation of H2, D2, and NH3 by 02 and of H2 by NO2 used the laser-induced fluorescence technique to measure the apparent desorption energies of OH radicals and the rotational energy accommodation of the desorbing OH, OD, and NO reaction products. The observed different degrees of "rotational cooling" in the different products are discussed. In multiphoton ionization mass spectrometry (MPI/MS) experiments, spectroscopies of three different MPI processes for the SiF2 radical were studied and two of these were applied to the study of silicon etching by XeF2, F2, and NF3. The only observed gaseous products were SiF4 and the SiF2 radical and their apparent production energies correlated with the ease of surface fluorine atom production. In the area of surface photochemistry, an excimer laser was used to photolyze iodobenzene, trimethylgallium, and trimethylindium adsorbed on a cold surface. The time-of-flight spectra of the fragments or reaction products were measured by using a mass spectrometer equipped with MPI or electron ionization (El).

Previous researchers have applied vertical motion parallax using video cameras; these attempts were published under the VISIDEP trademark. Alternatives are examined that can exploit computer graphics. Such techniques include choosing different locations for the axis of rotation and using multiple images versus dual images to make the motion smoother. These techniques as well as others are described and compared for effectiveness in enhancing depth.

A two-pupil heterodyne scanning system has been used previously to perform bipolar incoherent spatial filtering. In this paper, we exploit the system's potential in tunability. It is shown and verified experimentally that with two offset pupil functions, both having Gaussian shape, we can achieve tunable bandpass filtering operations. Potential applications in space-variant filtering on incoherent objects are discussed.

We propose a sinusoidal phase modulating laser diode interferometer that is insensitive to vibrations of the optical components and fluctuations in the optical wavelength of the laser diode. These external disturbances cause fluctuations in the phase of the interference signal. After we analyze the sinusoidal phase modulation in a laser diode interferometer, we describe the method of the feedback control of the injection current of the laser diode to eliminate the phase fluctuations of the interference signal. We construct two sinusoidal phase modulating interferometers for movement measurements and surface profile measurements, respectively. The experimental results make it clear that the interferometers work well in mechanically noisy circumstances.

This paper describes a method for testing a right angle prism, or any other optical component having a right angle, to subarcsecond accuracy. The method makes use of Haidinger fringes and is simple to use. Unlike autocollimation and Fizeau interferometer methods, it does not involve an expensive optical setup and has no aperture restriction. The sensitivity of the method can be suitably modified by changing the test setup parameters.