Theory and Applications of Holography

DeVelis, John B.; Reynolds, George O.; Cox, Mary E.

doi:10.1119/1.1974528

Cited by 29 publications

(7 citation statements)

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“…It is used to study vibration patterns on mechanical systems, but it is also well suited to detect density fluctuations in gases. For general information on this subject the reader is referred to the books of Collier and DeVelis (7,8).…”

Section: The Technique Of Interference Holographymentioning

confidence: 99%

Gas Flow Patterns in Horizontal Epitaxial Reactor Cells Observed by Interference Holography

Giling¹

1982

J. Electrochem. Soc.

148

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Interference holography is used to visualize gas flow patterns and temperature profiles in epitaxial systems. It is demonstrated that in water-cooled horizontal reactor cells the carrier gases H2 and He give dynamically stable laminar flow profiles throughout the reactor. There is no indication of a stagnant or boundary layer for flow velocities up to 80 cm/sec in this type of cell. In air-cooled cells, H2 and He also give stable laminar flow profiles, but beyond velocities of 40 cm/sec a cold gas finger appears in these flows due to undeveloped flow and temperature profiles. In contrast to the stable flow characteristics of H2 and He, the flows of N2 and Ar always are unstable due to convective motions. Besides this intrinsic instability, these flows are accompanied by severe entrance effects (especially undeveloped flow profiles), which dominate the flows for flow rates higher than 4 cm/sec. This is observed for both air-and water-cooled cells. Another phenomenom which is observed for N2 and Ar is that beyond 4 cm/sec the convective gas breaks up into a thin (8 ram) laminar layer close to the susceptor across which the entire temperature gradient is present and a highly turbulent/convective part above this laminar layer. Analysis shows that for Ar and N~ about eight times longer entrance lengths in the reactor cell are needed to achieve fully developed velocity and temperature profiles as compared with H.2 and He. This explains the dominant influence of this effect on the flows of Ar and N~. When the influence of the entrance effect on the profiles is taken into account, all the observed flow patterns and temperature gradients are in agreement with the theoretical flows which can be predicted on basis of the respective Reynolds and Rayleigh (or Grashof) numbers.Although chemical vapor deposition of silicon is widely used, the flow characteristics and the temperature profiles inside the epitaxial reactor are still a point of discussion. The system which is best studied in this connection is the horizontal epitaxial reactor cell. For this type of cell Eversteijn et al. (1, 2) studied the flow pattern of a stream of hydrogen in a horizontal water-cooled reactor by looking at the streamlines of a smoke of TiO2, obtained from TiCl~ and H20. From these experiments Eversteijn developed the stagnant layer model in which an immobile thin layer of gas of a few millimeters thickness was assumed to be present just above the heated susceptor. Ban (3, 4), in addition to flow visualization experiments with TiO2 smoke, measured temperature profiles with a moving thermocouple, while concentration measurements were performed by mass analysis. He concluded that the flows and temperatures in an air-cooled reactor were complicated by entrance effects. Sedgwick (5) determined temperature and concentration profiles by means of Raman scattering. He also used an air-cooled reactor and came to the conclusion that temperature profiles did depend on the position along the susceptor. In addition a steep temperature gradient was measured ab...

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Section: The Technique Of Interference Holographymentioning

confidence: 99%

Gas Flow Patterns in Horizontal Epitaxial Reactor Cells Observed by Interference Holography

Giling¹

1982

J. Electrochem. Soc.

148

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“…The reader is referred to an excellent bibliography that is available from the Japan Optical Engineering Research Association (Tanaka and Nakajima 1968-). For more general reading there are a number of books devoted to this field (Stroke 1966a, DeVelis and Reynolds 1967, Smith 1969, Kock 1969, Caulfield and Lu 1970, Lehmann 1970, Vienot et al 1971, Collier et a1 1971, Butters 1972, Cathey 1974. A series of review volumes also forms a standard part of the literature (Farhat 1975/76).…”

Section: The Modem Phase Of Holography 1962-pyesentmentioning

confidence: 99%

Applications of holography

Thompson

1978

Rep. Prog. Phys.

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The current status of holography and its applications are discussed with some historical background to place the current activity in perspective. Basic types of holograms are described together with their properties. Applications in optical image formation include photography, microscopy, image storage and image replication. Acoustic, x-ray, electron beam and microwave holography are briefly commented upon. The second major area of application is contour generation and interferometry. Finally, the current status of holographic optical elements is assessed.

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“…The input to Stage 1 is the incident complex-scalar disturbance pattern u; the output of the stage is the real, non-negative effective exposure pattern e. The effective exposure of the film over the time interval (t lo (2) at the point r = (x, y) in the plane of the emulsion is given by the equation…”

Section: Stage 1: Optical Diffusionmentioning

confidence: 99%

A Theory of Granularity and Bleaching for Holographic Information Recording

Lorber¹

1970

IBM J. Res. & Dev.

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The Kelly three-stage model of photographic information recording is a mathematical model of black-and-white silverhalide film with granularity neglected. In the work reported here, the theory is extended for use in phase-holographic applications. Granularity effects are contained in the fourth and final stage, a two-dimensional, nonhomogeneous, filtered Poisson process. The output of this stage is a sample function of the random process that describes the pattern of modification of the emulsion. Formulas for the signal-to-noise ratio of a hologram and the optimum granular behavior are derived as examples of the use of the granularity model. exposure Developed pattern Optical f---Sensitometry ----Chemical image diffusion diffusion Figure 1 The structure of Kelly's model of photographic information recording, showing the decomposition of the over-all operation into three spatially and temporally separated stages.a fourth stage is added following the chemical-diffusion stage to account for granularity and bleaching or etching of the emulsion.The design of the granularity stage is based on both conceptual and experimental considerations. Conceptually, it is reasonable to expect the effects of individual bleachedsilver grains to appear in a mathematical model as carriers as well as corrupters of information. (No grains, no hologram.) The similar dual role played by the electrons in a phototube suggests that the mathematical model of granularity effects should be closely related to the theory of shot noise in vacuum tubes. 3• 4 Those additional random fluctuations of amplitude transmission and phase shift in the hologram that are independent of granularity effects can be accounted for as additive or multiplicative noise.Admittedly, in a phototube all of the electrons are identical, whereas in a hologram all of the grains are different. The clouds of bleached or etched emulsion surrounding the bleached-out grains are also all different. IntroductionA decade ago D. H. Kellyl formulated a mathematical model of photographic information recording in terms of a sequence of three operations or stages connected in tandem, the output of one being the input of the next. To ensure that each operation was a separate entity, free of interaction with the other two, he separated the operations in space and time. That is, he noted that first the radiant-flux pattern incident on an emulsion sifts its way through the turbid emulsion and perhaps even bounces off the back of the film before it strikes the silver-halide crystals in the emulsion. It is only when the incident photons strike the crystals that they create latent-image centers on and in the crystals. And it is much later that the activated crystals, and perhaps their near neighbors, are developed into silver grains at a rate which depends on the local concentration of developer at the crystals. Thus, Kelly was led to describe the photographic process in terms of 1) an optical-diffusion stage functioning in the emulsion and its backing during exposure, 2) a sensitometry stage f...

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Theory and Applications of Holography

Cited by 29 publications

References 0 publications

Gas Flow Patterns in Horizontal Epitaxial Reactor Cells Observed by Interference Holography

Gas Flow Patterns in Horizontal Epitaxial Reactor Cells Observed by Interference Holography

Applications of holography

A Theory of Granularity and Bleaching for Holographic Information Recording

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